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1.  NOS2 enhances KRAS-induced lung carcinogenesis, inflammation and microRNA-21 expression 
Mutant KRAS in lung cancers induce molecular pathways that regulate cellular proliferation, survival and inflammation, which enhance tumorigenesis. Inducible nitric oxide synthese (NOS2) up-regulation and sustained nitric oxide (NO•) generation are induced during the inflammatory response and correlate positively with lung tumorigenesis. To explore the mechanistic contribution of NOS2 to KRAS-induced lung tumorigenesis and inflammation, we used a genetic strategy of crossing NOS2 knockout (NOS2KO) C57BL6 inbred mice with a KRASG12D-driven mouse lung cancer model. KRASG12D;NOS2KO mice exhibited delayed lung tumorigenesis and a longer overall survival time compared with that of KRASG12D;NOS2WT (wild-type) controls. Correspondingly, tumors in KRASG12D;NOS2KO mice had reduced tumor cell proliferation in adenomas and carcinomas. NOS2-deficiency also led to dramatically suppressed inflammatory response by attenuation of macrophage recruitment into alveoli and within tumor foci. In contrast, FOXP3+ regulatory T cells were increased in tumors from KRASG12D;NOS2KO mice. We further analyzed the expression of microRNA-21 (miR-21), an oncogenic non-coding RNA involved in oncogenic Ras signaling, by quantitative reverse transcription PCR and in situ hybridization. Lung carcinomas dissected from KRASG12D;NOS2KO mice showed a significantly reduced miR-21 expression along with decreased tumor cell proliferation, suggesting that NOS2-deficiency could attenuate RAS signaling pathways that transactivate miR-21 expression. Therefore, deletion of NOS2 decreases lung tumor growth as well as inflammatory responses initiated by oncogenic KRAS, suggesting that both KRAS and NOS2 cooperate in driving lung tumorigenesis and inflammation. Inhibition of NOS2 may have a therapeutic value in lung cancers with oncogenic KRAS mutations.
PMCID: PMC3473150  PMID: 22618808
Lung cancer; KRAS; NOS2; miR-21; inflammation
2.  MDM2 SNP285 does not antagonize the effect of SNP309 in lung cancer 
Conflicting reports exist regarding the contribution of SNP309 in MDM2 to cancer risk. Recently, SNP285 was shown to act as an antagonist to SNP309 by over-riding the effect of SNP309 on SP1-mediated transcription. Moreover, SNP285 modified the relationship between SNP309 and risk of breast, ovarian and endometrial cancer. We assessed whether SNP285 confounded the effect of SNP309 in lung cancer in a cohort of 720 controls and 556 cases. Our cohort included both Caucasians and African Americans. Neither SNP309 nor SNP285 were associated with lung cancer risk or survival. In addition, removal of individuals who carried the variant C allele of SNP285 did not modify the association between SNP309 with either lung cancer risk or survival. While an effect of SNP285 has been demonstrated in breast, ovarian and endometrial cancer, our findings do not support a role for this SNP in lung cancer and raise the possibility that the effect of SNP285 is restricted to cancers in women.
PMCID: PMC3414691  PMID: 22487911
3.  p53 isoforms regulate aging- and tumor-associated replicative senescence in T lymphocytes 
The Journal of Clinical Investigation  2013;123(12):5247-5257.
Cellular senescence contributes to aging and decline in tissue function. p53 isoform switching regulates replicative senescence in cultured fibroblasts and is associated with tumor progression. Here, we found that the endogenous p53 isoforms Δ133p53 and p53β are physiological regulators of proliferation and senescence in human T lymphocytes in vivo. Peripheral blood CD8+ T lymphocytes collected from healthy donors displayed an age-dependent accumulation of senescent cells (CD28–CD57+) with decreased Δ133p53 and increased p53β expression. Human lung tumor-associated CD8+ T lymphocytes also harbored senescent cells. Cultured CD8+ blood T lymphocytes underwent replicative senescence that was associated with loss of CD28 and Δ133p53 protein. In poorly proliferative, Δ133p53-low CD8+CD28– cells, reconstituted expression of either Δ133p53 or CD28 upregulated endogenous expression of each other, which restored cell proliferation, extended replicative lifespan and rescued senescence phenotypes. Conversely, Δ133p53 knockdown or p53β overexpression in CD8+CD28+ cells inhibited cell proliferation and induced senescence. This study establishes a role for Δ133p53 and p53β in regulation of cellular proliferation and senescence in vivo. Furthermore, Δ133p53-induced restoration of cellular replicative potential may lead to a new therapeutic paradigm for treating immunosenescence disorders, including those associated with aging, cancer, autoimmune diseases, and HIV infection.
PMCID: PMC3859419  PMID: 24231352
4.  The Role of microRNAs in Colorectal Cancer 
Cancer Journal (Sudbury, Mass.)  2012;18(3):244-252.
Over the last decade, it has become clear that aberrant microRNA expression has a functional role in the initiation and progression of colorectal cancer (CRC). Specific microRNAs can act as either tumor suppressors or oncogenes depending on the cellular environment in which they are expressed. The expression of microRNAs is reproducibly altered in CRC and their expression patterns are associated with diagnosis, prognosis and therapeutic outcome in CRC. Studies have begun to examine the association of microRNA related polymorphisms and their association with CRC incidence and prognosis as well as the possibility of using circulating microRNAs or fecal microRNA expression as non-invasive early detection biomarkers. These data suggest that microRNAs may be potential molecular classifiers, early detection biomarkers and therapeutic targets for CRC. Here, we will review the evidence demonstrating a role of microRNAs in CRC.
PMCID: PMC3397427  PMID: 22647361
5.  3′ UTR and functional secretor haplotypes in mannose-binding lectin 2 are associated with increased colon cancer risk in African Americans 
Cancer research  2012;72(6):1467-1477.
Because chronic intestinal inflammation is a risk factor for colorectal cancer, we hypothesized that genetic variants of inflammatory mediators, such as mannose-binding lectin 2 (MBL2), are associated with colon cancer susceptibility. Here we report the association of 24 MBL2 single nucleotide polymorphisms (SNPs) and corresponding haplotypes with colon cancer risk in a case-control study. Four SNPs in the 3′-UTR region of the gene (rs10082466, rs2120132, rs2099902, and rs10450310) were associated with an increased risk of colon cancer in African Americans. Odds ratios (OR) for homozygous variants vs. wild-type ranged from 3.17 (95% CI, 1.57–6.40) to 4.51 (95% CI, 1.94–10.50), whereas the 3′-UTR region haplotype consisting of these four variants had an OR of 2.10 (95% CI, 1.42–3.12). The C allele of rs10082466 exhibited a binding affinity of miR-27a and this allele was associated with both lower MBL plasma levels and activity. We found that 5′ secretor haplotypes known to correlate with moderate and low MBL serum levels exhibited associations with increased risk of colon cancer in African Americans, specifically as driven by two haplotypes LYPA and LYQC relative to the referent HYPA haplotype (LYPA: OR 2.60; 95% CI 1.33–5.08 and LYQC: OR 2.28; 95% CI 1.20–4.30). Similar associations were not displayed in Caucasians. Together, our results support the hypothesis that genetic variations in MBL2 increase colon cancer susceptibility in African Americans.
PMCID: PMC3306468  PMID: 22282660
colon cancer; single nucleotide polymorphism; mannose-binding lectin 2; innate immunity; African American
6.  Circulating microRNA Expression Profiles in Early Stage Non-Small Cell Lung Cancer 
Circulating micro-RNA (miR) profiles have been proposed as promising diagnostic and prognostic biomarkers for cancer, including lung cancer. We have developed methods to accurately and reproducibly measure microRNA levels in serum and plasma. Here we study paired serum and plasma samples from 220 patients with early stage NSCLC and 220 matched controls. We use qRT-PCR to measure the circulating levels of 30 different miRs that have previously been reported to be differently expressed in lung cancer tissue. Duplicate RNA extractions were performed for 10% of all samples and microRNA measurements were highly correlated among those duplicates. This demonstrates high reproducibility of our assay. The expression of miR-146b, miR-221, let-7a, miR-155, miR-17-5p, miR-27a and miR-106a were significantly reduced in the serum of NSCLC cases while miR-29c was significantly increased. No significant differences were observed in plasma of patients compared to controls. Overall, expression levels in serum did not correlate well with levels in plasma. In secondary analyses, reduced plasma expression of let-7b was modestly associated with worse cancer-specific mortality in all patients and reduced serum expression of miR-223 was modestly associated with cancer-specific mortality in stage IA/B patients. MiR profiles also showed considerable differences comparing African American and European Americans. In summary, we found significant differences in miR expression when comparing cases and controls and find evidence that expression of let-7b is associated with prognosis in NSCLC.
PMCID: PMC3259258  PMID: 21544802
7.  Increased Levels of Circulating Interleukin 6, Interleukin 8, C-Reactive Protein, and Risk of Lung Cancer 
Previous studies that were based primarily on small numbers of patients suggested that certain circulating proinflammatory cytokines may be associated with lung cancer; however, large independent studies are lacking.
Associations between serum interleukin 6 (IL-6) and interleukin 8 (IL-8) levels and lung cancer were analyzed among 270 case patients and 296 control subjects participating in the National Cancer Institute-Maryland (NCI-MD) case–control study. Results were validated in 532 case patients and 595 control subjects in a nested case–control study within the prospective Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Association with C-reactive protein (CRP), a systemic inflammation biomarker, was also analyzed. Associations between biomarkers and lung cancer were estimated using logistic regression models adjusted for smoking, stage, histology, age, and sex. The 10-year standardized absolute risks of lung cancer were estimated using a weighted Cox regression model.
Serum IL-6 and IL-8 levels in the highest quartile were associated with lung cancer in the NCI-MD study (IL-6, odds ratio [OR] = 3.29, 95% confidence interval [CI] = 1.88 to 5.77; IL-8, OR = 2.06, 95% CI = 1.19 to 3.57) and with lung cancer risk in the PLCO study (IL-6, OR = 1.48, 95% CI = 1.04 to 2.10; IL-8, OR = 1.57, 95% CI = 1.10 to 2.24), compared with the lowest quartile. In the PLCO study, increased IL-6 levels were only associated with lung cancer diagnosed within 2 years of blood collection, whereas increased IL-8 levels were associated with lung cancer diagnosed more than 2 years after blood collection (OR = 1.57, 95% CI = 1.15 to 2.13). The 10-year standardized absolute risks of lung cancer in the PLCO study were highest among current smokers with high IL-8 and CRP levels (absolute risk = 8.01%, 95% CI = 5.77% to 11.05%).
Although increased levels of both serum IL-6 and IL-8 are associated with lung cancer, only IL-8 levels are associated with lung cancer risk several years before diagnosis. Combination of IL-8 and CRP are more robust biomarkers than either marker alone in predicting subsequent lung cancer.
PMCID: PMC3139587  PMID: 21685357
8.  Inflammatory and microRNA Gene Expression as Prognostic Classifiers of Barrett's Associated Esophageal Adenocarcinoma 
Esophageal cancer is one of the most aggressive and deadly forms of cancer; highlighting the need to identify biomarkers for early detection and prognostic classification. Our recent studies have identified inflammatory gene and microRNA signatures derived from tumor and nontumor tissues as prognostic biomarkers of hepatocellular, lung, and colorectal adenocarcinoma. Here, we examine the relationship between expression of these inflammatory genes and miRNA expression in esophageal adenocarcinoma and patient survival.
Experimental Design
We measured the expression of 23 inflammation-associated genes in tumors and adjacent normal tissues from 93 patients (58 Barrett's and 35 Sporadic adenocarcinomas) by quantitative reverse transcription-polymerase chain reaction. These data were used to build an inflammatory risk model, based on multivariate Cox regression, to predict survival in a training cohort (n=47). We then determined if this model could predict survival in a cohort of 46 patients. Expression data for miRNA-375 was available for these patients and was combined with inflammatory gene expression.
IFNγ, IL-1α, IL-8, IL-21, IL-23, and PRG expression in tumor and nontumor samples were each associated with poor prognosis based on Cox regression ([Z-score]>1.5) and therefore, were used to generate an inflammatory risk score (IRS). Patients with a high IRS had poor prognosis compared to those with a low IRS in the training (P=0.002) and test (P=0.012) cohorts. This association was stronger in the group with Barrett's history. When combining with miRNA-375, the combined IRS/miR signature was an improved prognostic classifier than either one alone.
Transcriptional profiling of inflammation-associated genes and miRNA expression in resected esophageal Barrett's associated adenocarcinoma tissues may have clinical utility as predictors of prognosis.
PMCID: PMC2999658  PMID: 20947516
Inflammation; Cancer; Barrett's; Esophagus
9.  p53 governs telomere regulation feedback too, via TRF2 
Aging (Albany NY)  2011;3(1):26-32.
p53 takes critical part in a number of positive and negative feedback loops to regulate carcinogenesis, aging and other biological processes. Uncapped or dysfunctional telomeres are an endogenous DNA damage that activates ATM kinase (ataxia telangiectasia mutated) and then p53 to induce cellular senescence or apoptosis. Our recent study shows that p53, a downstream effector of the telomere damage signaling, also functions upstream of the telomere-capping protein complex by inhibiting one of its components, TRF2 (telomeric repeat binding factor 2). Since TRF2 inhibition leads to ATM activation, a novel positive feedback loop exists to amplify uncapped telomere-induced, p53-mediated cellular responses. Siah1 (seven in absentia homolog 1), a p53-inducible E3 ubiquitin ligase, plays a key role in this feedback regulation by targeting TRF2 for ubiquitination and proteasomal degradation. Biological significance and therapeutic implications of this study are discussed.
PMCID: PMC3047136  PMID: 21266744
telomere uncapping; p53; ubiquitin ligase; TRF2; feedback regulation
10.  Childhood Exposure to Secondhand Smoke and Functional Mannose Binding Lectin Polymorphisms Are Associated with Increased Lung Cancer Risk 
Exposure to secondhand smoke during adulthood has detrimental health effects, including increased lung cancer risk. Compared with adults, children may be more susceptible to secondhand smoke. This susceptibility may be exacerbated by alterations in inherited genetic variants of innate immunity genes. We hypothesized a positive association between childhood secondhand smoke exposure and lung cancer risk that would be modified by genetic polymorphisms in the mannose binding lectin-2 (MBL2) gene resulting in well-known functional changes in innate immunity.
Childhood secondhand smoke exposure and lung cancer risk was assessed among men and women in the ongoing National Cancer Institute-Maryland Lung Cancer (NCI-MD) study, which included 624 cases and 348 controls. Secondhand smoke history was collected via in-person interviews. DNA was used for genotyping the MBL2 gene. To replicate, we used an independent case-control study from Mayo Clinic consisting of 461 never smokers, made up of 172 cases and 289 controls. All statistical tests were two-sided.
In the NCI-MD study, secondhand smoke exposure during childhood was associated with increased lung cancer risk among never smokers [odds ratio (OR), 2.25; 95% confidence interval (95% CI), 1.04-4.90]. This was confirmed in the Mayo study (OR, 1.47; 95% CI, 1.00-2.15). A functional MBL2 haplotype associated with high circulating levels of MBL and increased MBL2 activity was associated with increased lung cancer risk among those exposed to childhood secondhand smoke in both the NCI-MD and Mayo studies (OR, 2.52; 95% CI, 1.13-5.60, and OR, 2.78; 95% CI, 1.18-3.85, respectively).
Secondhand smoke exposure during childhood is associated with increased lung cancer risk among never smokers, particularly among those possessing a haplotype corresponding to a known overactive complement pathway of the innate immune system.
PMCID: PMC2951599  PMID: 19959685
11.  MiRNA expression in squamous cell carcinoma and adenocarcinoma of the esophagus and associations with survival 
The dismal outcome of esophageal cancer patients highlights the need for novel prognostic biomarkers, such as microRNAs (miRNAs). While recent studies have established the role of miRNAs in esophageal carcinoma, a comprehensive multi-center study investigating different histological types, including squamous cell carcinoma (SCC) and adenocarinoma (ADC) with or without Barrett's, is still lacking.
Experimental Design
MiRNA expression was measured in cancerous and adjacent non-cancerous tissue pairs collected from 100 ADC and 70 SCC patients enrolled at 4 clinical centers from the US, Canada, and Japan. Microarray-based expression was measured in a subset of samples in two cohorts and was validated in all available samples.
In ADC patients, miR-21, miR-223, miR-192, and miR-194 expression was elevated, while miR-203 expression was reduced in cancerous compared to non-cancerous tissue. In SCC patients, we found elevated miR-21 and reduced mir-375 expression levels in cancerous compared to non-cancerous tissue. When comparing cancerous tissue expression between ADC and SCC patients, mir-194 and mir-375 were elevated in ADC patients. Significantly, elevated mir-21 expression in non-cancerous tissue of SCC patients and reduced levels of mir-375 in cancerous tissue of ADC patients with Barrett's were strongly associated with worse prognosis. Associations with prognosis were independent of tumor stage or nodal status, cohort type, and chemoradiation therapy.
Our multi-center-based results highlight miRNAs involved in major histological types of esophageal carcinoma and uncover significant associations with prognosis. Elucidating miRNAs relevant to esophageal carcinogenesis is potentially clinically useful for developing prognostic biomarkers and identifying novel drug targets and therapies.
PMCID: PMC2933109  PMID: 19789312
microRNA; esophageal cancer; prognosis; Barrett's; expression profiling
13.  Association of inflammation-related and microRNA gene expression with cancer specific mortality of colon adenocarcinoma 
Translational Relevance
We report that the expression pattern of inflammatory-related genes in tumors and paired noncancerous tissues was an independent prognostic marker for colon adenocarcinoma patients. This gene signature was associated with prognosis in early stage patients. Therefore, this gene signature may be useful to identify high risk, early stage patients to assist in decisions regarding appropriate therapeutic intervention. We also show that combining independent biomarkers can improve predictions over single biomarkers. The combination of the inflammatory gene signature with available microRNA-21 expression data improved predictions with prognosis over either alone. These findings demonstrate the potential of IRS and/or microRNA-21 to be used as prognostic biomarkers for early stage colon cancer.
Inflammatory genes and microRNAs have roles in colon carcinogenesis; therefore, they may provide useful biomarkers for colon cancer. This study examines the potential clinical utility of an inflammatory gene expression signature as a prognostic biomarker for colon cancer in addition to previously examined microRNA-21 expression.
Experimental Design
Quantitative RTPCR measured the expression 23 inflammatory genes in colon adenocarcinomas and adjacent noncancerous tissues from 196 patients. These data were used to develop models for cancer-specific mortality on a training cohort (n=57) and this model was tested in both a test (n=56) and validation (n=83) cohort. Expression data for microRNA-21 was available for these patients and was compared to and combined with inflammatory gene expression.
PRG1, IL-10, CD68, IL-23a, and IL-12a expression in noncancerous tissue and PRG1, ANXA1, IL-23a, IL-17a, FOXP3 and HLA-DRA expression in tumor tissues were associated with poor prognosis based on Cox regression (|Z-score| > 1.5) and were used to generate the inflammatory risk score (IRS). IRS was associated with cancer-specific mortality in the training, test (P=0.01) and validation (P=0.02) cohorts. This association was strong for stage II cases (P=0.002). microRNA-21 expression was associated with IL-6, IL-8, IL-10, IL-12a and NOS2a, providing evidence that the function of this microRNA and these inflammatory genes are linked. Both IRS and microRNA-21 expression were independently associated with cancer-specific mortality, including stage II patients alone.
IRS and microRNA-21 expression are independent predictors of colon cancer prognosis and may provide a clinically useful tool to identify high risk patients.
PMCID: PMC2745503  PMID: 19737943
14.  Serum Concentrations of Cytokines and Lung Cancer Survival in African Americans and Caucasians 
Accumulating evidence suggests a role for inflammation in the development and progression of cancer. Our group recently identified a cytokine gene signature in lung tissue associated with lung cancer prognosis. Therefore, we hypothesized that concentrations of circulating cytokines in serum may be associated with lung cancer survival. Ten serum cytokines, namely, interleukin (IL)-1β, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, granulocyte macrophage colony-stimulating factor, interferon (IFN)-γ, and tumor necrosis factor-α, were assessed in 353 non–small cell lung cancer cases from a case-control study of lung cancer in the greater Baltimore, Maryland area. Cytokines were measured using an ultrasensitive electrochemiluminescence immunoassay. IL-6 serum concentrations (≥4.0 pg/mL) were associated with significantly poorer survival in both African Americans [hazard ratio (HR), 2.71; 95% confidence interval (CI), 1.26–5.80] and Caucasians (HR, 1.71; 95% CI, 1.22–2.40). IL-10 (HR, 2.62; 95% CI, 1.33–5.15) and IL-12 (HR, 1.98; 95% CI, 1.14–3.44) were associated with lung cancer survival only in African Americans. Some evidence for an association of tumor necrosis factor-α levels with survival in Caucasians was observed, although these results were not significant. These hypothesis-generating findings indicate that selected serum cytokine concentrations are associated with lung cancer survival, and indicate that further research is warranted to better understand the mechanistic underpinnings of these associations.
PMCID: PMC2790156  PMID: 19124500
15.  The 20th Aspen Cancer Conference 
Molecular carcinogenesis  2008;47(9):707-732.
PMCID: PMC2610844  PMID: 18286481
16.  Advances in Chemical Carcinogenesis: A Historical Review and Prospective 
Cancer research  2008;68(17):6863-6872.
PMCID: PMC2583449  PMID: 18757397
17.  Nitric Oxide Is a Key Component in Inflammation-Accelerated Tumorigenesis 
Cancer research  2008;68(17):7130-7136.
Nitric oxide (NO•), an important signaling molecule and a component of inflammatory response, is involved in tumorigenesis. However, the quantity of NO• and the cellular micro-environment influences the role of NO• in tumor development. We used a genetic strategy to test the hypothesis that an inflammatory microenvironment with an enhanced level of NO• accelerates spontaneous tumor development. C. parvum–induced inflammation and increased NO• synthase-2 (NOS2) expression coincided with accelerated spontaneous tumor development, mostly lymphomas, in p53−/−NOS2+/+ C57BL6 mice when compared with the controls (P = 0.001). However, p53−/−NOS2−/− mice did not show any difference in tumor latency between C. parvum–treated and control groups. In C. parvum–treated p53−/−NOS2+/+ mice, tumor development was preceded by a higher expression of NOS2 and phosphorylated Akt-Ser473 (pAkt-Ser473) in spleen, increased cell proliferation measured by Ki-67 IHC in spleen and thymus, and a lower apoptotic index and CD95-L expression in spleen and thymus. C. parvum–treated p53−/−NOS2+/+ mice showed an increase in the number of Foxp3(+) T-reg cells, dendritic cells (DC), as well as increased CD80+, CD86+, CD40+, and CD83+ on DC in the spleen. Regulatory T-cells (T-reg) and the maturation of DC may modulate tumorigenesis. An increase in the FoxP3(+)T-reg cells in C. parvum–treated p53−/−NOS2+/+ mice indicates a role of NO• in the regulation of T-reg cells that may contribute to a protumor shift of the immune environment favoring an accelerated tumor development. These data provide genetic and mechanistic evidence that an inflammatory microenvironment and an increased level of NO• can accelerate tumor development.
PMCID: PMC2576291  PMID: 18757428
19.  Nutlin-3a Activates p53 to Both Down-regulate Inhibitor of Growth 2 and Up-regulate mir-34a, mir-34b, and mir-34c Expression, and Induce Senescence 
Cancer research  2008;68(9):3193-3203.
Nutlin-3, an MDM2 inhibitor, activates p53, resulting in several types of cancer cells undergoing apoptosis. Although p53 is mutated or deleted in ~50% of all cancers, p53 is still functionally active in the other 50%. Consequently, nutlin-3 and similar drugs could be candidates for neoadjuvant therapy in cancers with a functional p53. Cellular senescence is also a phenotype induced by p53 activation and plays a critical role in protecting against tumor development. In this report, we found that nutlin-3a can induce senescence in normal human fibroblasts. Nutlin-3a activated and repressed a large number of p53-dependent genes, including those encoding microRNAs. mir-34a, mir-34b, and mir-34c, which have recently been shown to be downstream effectors of p53-mediated senescence, were up-regulated, and inhibitor of growth 2 (ING2) expression was suppressed by nutlin-3a treatment. Two candidates for a p53-DNA binding consensus sequence were found in the ING2 promoter regulatory region; thus, we performed chromatin immunoprecipitation and electrophoretic mobility shift assays and confirmed p53 binding directly to those sites. In addition, the luciferase activity of a construct containing the ING2 regulatory region was repressed after p53 activation. Antisense knockdown of ING2 induces p53-independent senescence, whereas overexpression of ING2 induces p53-dependent senescence. Taken together, we conclude that nutlin-3a induces senescence through p53 activation in normal human fibroblasts, and p53-mediated mir34a, mir34b, and mir34c up-regulation and ING2 down-regulation may be involved in the senescence pathway.
PMCID: PMC2440635  PMID: 18451145
20.  MicroRNA Expression Profiles Associated With Prognosis and Therapeutic Outcome in Colon Adenocarcinoma 
MicroRNAs have potential as diagnostic biomarkers and therapeutic targets in cancer. No study has evaluated the association between microRNA expression patterns and colon cancer prognosis or therapeutic outcome.
To identify microRNA expression patterns associated with colon adenocarcinomas, prognosis, or therapeutic outcome.
Design, Setting, and Patients
MicroRNA microarray expression profiling of tumors and paired nontumorous tissues was performed on a US test cohort of 84 patients with incident colon adenocarcinoma, recruited between 1993 and 2002. We evaluated associations with tumor status, TNM staging, survival prognosis, and response to adjuvant chemotherapy. Associations were validated in a second, independent Chinese cohort of 113 patients recruited between 1991 and 2000, using quantitative reverse transcription polymerase chain reaction assays. The final date of follow-up was December 31, 2005, for the Maryland cohort and August 16, 2004, for the Hong Kong cohort.
Main Outcome Measures
MicroRNAs that were differentially expressed in tumors and microRNA expression patterns associated with survival using cancer-specific death as the end point.
Thirty-seven microRNAs were differentially expressed in tumors from the test cohort. Selected for validation were miR-20a, miR-21, miR-106a, miR-181b, and miR-203, and all 5 were enriched in tumors from the validation cohort (P<.001). Higher miR-21 expression was present in adenomas (P = .006) and in tumors with more advanced TNM staging (P<.001). In situ hybridization demonstrated miR-21 to be expressed at high levels in colonic carcinoma cells. The 5-year cancer-specific survival rate was 57.5% for the Maryland cohort and was 49.5% for the Hong Kong cohort. High miR-21 expression was associated with poor survival in both the training (hazard ratio, 2.5; 95% confidence interval, 1.2-5.2) and validation cohorts (hazard ratio, 2.4; 95% confidence interval, 1.4-3.9), independent of clinical covariates, including TNM staging, and was associated with a poor therapeutic outcome.
Expression patterns of microRNAs are systematically altered in colon adenocarcinomas. High miR-21 expression is associated with poor survival and poor therapeutic outcome.
PMCID: PMC2614237  PMID: 18230780
21.  The p53 Tumor Suppressor Network Is a Key Responder to Microenvironmental Components of Chronic Inflammatory Stress 
Cancer research  2005;65(22):10255-10264.
Activation of the p53 network plays a central role in the inflammatory stress response associated with ulcerative colitis and may modulate cancer risk in patients afflicted with this chronic disease. Here, we describe the gene expression profiles associated with four microenvironmental components of the inflammatory response (NO•, H2O2, DNA replication arrest, and hypoxia) that result in p53 stabilization and activation. Isogenic HCT116 and HCT116 TP53−/− colon cancer cells were exposed to the NO• donor Sper/NO, H2O2, hypoxia, or hydroxyurea, and their mRNA was analyzed using oligonucleotide microarrays. Overall, 1,396 genes changed in a p53-dependent manner (P < 0.001), with the majority representing a “unique” profile for each condition. Only 14 genes were common to all four conditions. Included were eight known p53 target genes. Hierarchical sample clustering distinguished early (1 and 4 hours) from late responses (8, 12, and 24 hours), and each treatment was differentiated from the others. Overall, NO• and hypoxia stimulated similar transcriptional responses. Gene ontology analysis revealed cell cycle as a key feature of stress responses and confirmed the similarity between NO• and hypoxia. Cell cycle profiles analyzed by flow cytometry showed that NO• and hypoxia induced quiescent S-phase and G2-M arrest. Using a novel bioinformatic algorithm, we identified several putative p53-responsive elements among the genes induced in a p53-dependent manner, including four [KIAA0247, FLJ12484, p53CSV (HSPC132), and CNK (PLK3)] common to all exposures. In summary, the inflammatory stress response is a complex, integrated biological network in which p53 is a key molecular node regulating gene expression.
PMCID: PMC1421332  PMID: 16288013
22.  Less Efficient G2-M Checkpoint Is Associated with an Increased Risk of Lung Cancer in African Americans 
Cancer research  2005;65(20):9566-9573.
Cell cycle checkpoints play critical roles in the maintenance of genomic integrity. The inactivation of checkpoint genes by genetic and epigenetic mechanisms is frequent in all cancer types, as a less-efficient cell cycle control can lead to genetic instability and tumorigenesis. In an on-going case-control study consisting of 216 patients with non–small cell lung cancer, 226 population-based controls, and 114 hospital-based controls, we investigated the relationship of γ-radiation-induced G2-M arrest and lung cancer risk. Peripheral blood lymphocytes were cultured for 90 hours, exposed to 1.0 Gy γ-radiation, and harvested at 3 hours after γ-radiation treatment. γ-Radiation-induced G2-M arrest was measured as the percentage of mitotic cells in untreated cultures minus the percentage of mitotic cells in γ-radiation-treated cultures from the same subject. The mean percentage of γ-radiation-induced G2-M arrest was significantly lower in cases than in population controls (1.18 versus 1.44, P < 0.01) and hospital controls (1.18 versus 1.40, P = 0.01). When dichotomized at the 50th percentile value in combined controls (population and hospital controls), a lower level of γ-radiation-induced G2-M arrest was associated with an increased risk of lung cancer among African Americans after adjusting for baseline mitotic index, age, gender, and pack-years of smoking [adjusted odd ratio (OR), 2.25; 95% confidence interval (95% CI), 0.97–5.20]. A significant trend of an increased risk of lung cancer with a decreased level of G2-M arrest was observed (Ptrend = 0.02) among African Americans, with a lowest-versus-highest quartile adjusted OR of 3.74 (95% CI, 0.98–14.3). This trend was most apparent among African American females (Ptrend < 0.01), with a lowest-versus-highest quartile adjusted OR of 11.75 (95% CI, 1.47–94.04). The results suggest that a less-efficient DNA damage–induced G2-M checkpoint is associated with an increased risk of lung cancer among African Americans. Interestingly, we observed a stronger association of DNA damage–induced G2-M arrest and lung cancer among African Americans when compared with Caucasians. If replicated, these results may provide clues to the exceedingly high lung cancer incidence experienced by African Americans.
PMCID: PMC1403288  PMID: 16230422
23.  WNT10B Functional Dualism: β-Catenin/Tcf-dependent Growth Promotion or Independent Suppression with Deregulated Expression in Cancer 
Molecular Biology of the Cell  2007;18(11):4292-4303.
We found aberrant DNA methylation of the WNT10B promoter region in 46% of primary hepatocellular carcinoma (HCC) and 15% of colon cancer samples. Three of 10 HCC and one of two colon cancer cell lines demonstrated low or no expression, and 5-aza-2′deoxycytidine reactivated WNT10B expression with the induction of demethylation, indicating that WNT10B is silenced by DNA methylation in some cancers, whereas WNT10B expression is up-regulated in seven of the 10 HCC cell lines and a colon cancer cell line. These results indicate that WNT10B can be deregulated by either overexpression or silencing in cancer. We found that WNT10B up-regulated β-catenin/Tcf activity. However, WNT10B-overexpressing cells demonstrated a reduced growth rate and anchorage-independent growth that is independent of the β-catenin/Tcf activation, because mutant β-catenin–transduced cells did not suppress growth, and dominant-negative hTcf-4 failed to alleviate the growth suppression by WNT10B. Although WNT10B expression alone inhibits cell growth, it acts synergistically with the fibroblast growth factor (FGF) to stimulate cell growth. WNT10B is bifunctional, one function of which is involved in β-catenin/Tcf activation, and the other function is related to the down-regulation of cell growth through a different mechanism. We suggest that FGF switches WNT10B from a negative to a positive cell growth regulator.
PMCID: PMC2043567  PMID: 17761539
24.  Innate immunity gene polymorphisms and the risk of colorectal neoplasia 
Carcinogenesis  2013;34(11):2512-2520.
Inherited variation in genes that regulate innate immunity and inflammation may contribute to colorectal neoplasia risk. To evaluate this association, we conducted a nested case–control study of 451 colorectal cancer cases, 694 colorectal advanced adenoma cases and 696 controls of European descent within the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. A total of 935 tag single-nucleotide polymorphisms (SNPs) in 98 genes were evaluated. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association with colorectal neoplasia. Sixteen SNPs were associated with colorectal neoplasia risk at P < 0.01, but after adjustment for multiple testing, only rs2838732 (ITGB2) remained suggestively associated with colorectal neoplasia (ORper T allele = 0.68, 95% CI: 0.57–0.83, P = 7.7 × 10–5, adjusted P = 0.07). ITGB2 codes for the CD18 protein in the integrin beta chain family. The ITGB2 association was stronger for colorectal cancer (ORper T allele = 0.41, 95% CI: 0.30–0.55, P = 2.4 × 10− 9) than for adenoma (ORper T allele = 0.84, 95%CI: 0.69–1.03, P = 0.08), but it did not replicate in the validation study. The ITGB2 rs2838732 association was significantly modified by smoking status (P value for interaction = 0.003). Among never and former smokers, it was inversely associated with colorectal neoplasia (ORper T allele = 0.5, 95% CI: 0.37–0.69 and ORper T allele = 0.72, 95% CI: 0.54–0.95, respectively), but no association was seen among current smokers. Other notable findings were observed for SNPs in BPI/LBP and MYD88. Although the results need to be replicated, our findings suggest that genetic variation in inflammation-related genes may be related to the risk of colorectal neoplasia.
PMCID: PMC3810838  PMID: 23803696
25.  Functional interaction between BLM helicase and 53BP1 in a Chk1-mediated pathway during S-phase arrest 
The Journal of Cell Biology  2004;166(6):801-813.
Bloom's syndrome is a rare autosomal recessive genetic disorder characterized by chromosomal aberrations, genetic instability, and cancer predisposition, all of which may be the result of abnormal signal transduction during DNA damage recognition. Here, we show that BLM is an intermediate responder to stalled DNA replication forks. BLM colocalized and physically interacted with the DNA damage response proteins 53BP1 and H2AX. Although BLM facilitated physical interaction between p53 and 53BP1, 53BP1 was required for efficient accumulation of both BLM and p53 at the sites of stalled replication. The accumulation of BLM/53BP1 foci and the physical interaction between them was independent of γ-H2AX. The active Chk1 kinase was essential for both the accurate focal colocalization of 53BP1 with BLM and the consequent stabilization of BLM. Once the ATR/Chk1- and 53BP1-mediated signal from replicational stress is received, BLM functions in multiple downstream repair processes, thereby fulfilling its role as a caretaker tumor suppressor.
PMCID: PMC2172115  PMID: 15364958
replication arrest; γ-H2AX; p53; homologous recombination; signal transduction

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