Angiogenesis has long been considered an important target for cancer therapy. Initial efforts have primarily focused on targeting of endothelial and tumor-derived vascular endothelial growth factor signaling. As evidence emerges that angiogenesis has significant mechanistic complexity, therapeutic resistance and escape have become practical limitations to drug development. Here, we review the mechanisms by which dynamic changes occur in the tumor microenvironment in response to antiangiogenic therapy, leading to drug resistance. These mechanisms include direct selection of clonal cell populations with the capacity to rapidly upregulate alternative proangiogenic pathways, increased invasive capacity, and intrinsic resistance to hypoxia. The implications of normalization of vasculature with subsequently improved vascular function as a result of antiangiogenic therapy are explored, as are the implications of the ability to incorporate and co-opt otherwise normal vasculature. Finally, we consider the extent to which a better understanding of the biology of hypoxia and reoxygenation, as well as the depth and breadth of systems invested in angiogenesis, may offer putative biomarkers and novel therapeutic targets. Insights gained through this work may offer solutions for personalizing antiangiogenesis approaches and improving the outcome of patients with cancer.
To evaluate the prognostic value of fibroblast growth factor receptor 4 (FGFR4) protein expression in patients with advanced-stage, high-grade serous ovarian cancer, delineate the functional role of FGFR4 in ovarian cancer progression, and evaluate the feasibility of targeting FGFR4 in serous ovarian cancer treatment.
Immunolocalization of FGFR4 was performed on 183 ovarian tumor samples. The collected FGFR4 expression data were correlated with overall survival using Kaplan-Meier and Cox regression analyses. The effects of FGFR4 silencing on ovarian cancer cell growth, survival, invasiveness, apoptosis and FGF1-mediated signaling pathway activation were evaluated by transfecting cells with FGFR4-specific small interfering RNAs (siRNAs). An orthotopic mouse model was used to evaluate the effect of injection of FGFR4-specific siRNAs and FGFR4 trap protein encapsulated in nanoliposomes on ovarian tumor growth in vivo.
Overexpression of FGFR4 protein was significantly associated with decreased overall survival durations. FGFR4 silencing significantly decreased the proliferation, survival, and invasiveness and increased apoptosis of ovarian cancer cells. Also, downregulation of FGFR4 significantly abrogated the mitogen-activated protein kinase (MAPK), nuclear factor-κB (NFκB), and WNT signaling pathways, which are activated by FGF1. Targeting FGFR4 with the FGFR4-specific siRNAs and FGFR4 trap protein significantly decreased ovarian tumor growth in vivo.
FGFR4 is a prognostic marker for advanced-stage, high-grade serous ovarian carcinoma. Silencing FGFR4 and inhibiting ligand-receptor binding significantly decrease ovarian tumor growth both in vitro and in vivo, suggesting that targeting ovarian cancer cells with high levels of FGFR4 protein expression is a new therapeutic modality for this disease and will improve survival of it.
serous ovarian carcinoma; FGFR4; FGF1; nanoliposomes; FGF trap
Integrated genomic analyses revealed a miRNA-regulatory network, which further defined a robust integrated mesenchymal subtype associated with poor overall survival in 459 cases of serous ovarian cancer (OvCa) from The Cancer Genome Atlas and 560 cases from independent cohorts. Eight key miRNAs, including miR-506, miR-141 and miR-200a, were predicted to regulate 89% of the targets in this network. Follow-up functional experiments illustrate that miR-506 augmented E-cadherin expression, inhibited cell migration and invasion, and prevented TGFβ-induced epithelial-mesenchymal transition (EMT) by targeting SNAI2, a transcriptional repressor of E-cadherin. In human OvCa, miR-506 expression was correlated with decreased SNAI2 and VIM, elevated E-cadherin, and beneficial prognosis. Nanoparticle delivery of miR-506 in orthotopic OvCa mouse models led to E-cadherin induction and reduced tumor growth.
Endoglin (ENG, CD105) is a membranous protein overexpressed in tumor-associated endothelial cells, chemoresistant populations of ovarian cancer cells, and potentially stem cells. Our objective was to evaluate the effects and mechanisms of targeting endoglin in ovarian cancer.
Global and membranous endoglin expression was evaluated in multiple ovarian cancer lines. In vitro, the effects of siRNA-mediated endoglin knockdown with and without chemotherapy were evaluated by MTT assay, cell-cycle analysis, alkaline comet assay, γ-H2AX foci formation, and qPCR. In an orthotopic mouse model, endoglin was targeted with chitosan-encapsulated siRNA with and without carboplatin.
Endoglin expression was surprisingly predominantly cytoplasmic, with a small population of surface-positive cells. Endoglin inhibition decreased cell viability, increased apoptosis, induced double-stranded DNA damage, and increased cisplatin sensitivity. Targeting endoglin downregulates expression of numerous DNA repair genes, including BARD1, H2AFX, NBN, NTHL1, and SIRT1. BARD1 was also associated with platinum resistance, and was induced by platinum exposure. In vivo, anti-endoglin treatment decreased tumor weight in both ES2 and HeyA8MDR models when compared to control (35-41% reduction, p<0.05). Endoglin inhibition with carboplatin was associated with even greater inhibitory effect when compared to control (58-62% reduction, p<0.001).
Endoglin downregulation promotes apoptosis, induces significant DNA damage through modulation of numerous DNA repair genes, and improves platinum sensitivity both in vivo and in vitro. Anti-endoglin therapy would allow dual treatment of both tumor angiogenesis and a subset of aggressive tumor cells expressing endoglin and is being actively pursued as therapy in ovarian cancer.
Endoglin; CD105; platinum resistance; ovarian cancer; siRNA; cancer stem cells
Behavioral stress is known to promote tumor progression in experimental models, but
the role of behavioral stress in cancer initiation is less clear. In this issue,
Hassan et al. focus on the signaling and biological effects induced by stress
hormones that lead to tumor cell evasion from apoptosis, resulting in prostate cancer
Cytotoxic therapy and surgery have improved outcomes for patients with gynecologic malignancies over the last twenty years, but women’s cancers still account for over ten percent of cancer related deaths annually. Insights into the pathogenesis of cancer have led to the development of drugs that target molecular pathways essential to tumor survival including angiogenesis, DNA repair, and apoptosis. This review outlines several of the promising new biologically targeted drugs currently being tested to treat gynecologic malignancies.
Angiogenesis; AZD2171; cediranib; AZD2281; olaparib; Bevacizumab; BIBF-1120; Cervical cancer; Cetuximab; Epidermal growth factor (EGF); Epidermal growth factor receptor (EGFR); Endometrial cancer; Erlotinib; Everolimus; Gefitinib; Gynecologic cancer; mTOR; Pazopanib; PTEN; Poly; ADP-ribose; polymerase; PARP inhibitor; Ovarian cancer; Sorafenib; Sunitinib; Temsirolimus; Vascular endothelial growth factor; VEGF; Vascular endothelial growth factor receptor; VEGFR; VEGF Trap
The dynamic properties of RNA interference (RNAi) in cancer biology have led investigators to pursue with significant interest its role in tumorigenesis and cancer therapy. We recently reported that decreased expression of key RNAi enzymes, Dicer and Drosha, in epithelial ovarian cancers was associated with poor clinical outcome in patients. Dicer expression was also functionally relevant in that targeted silencing was limited with RNAi fragments that require Dicer function compared with those that do not. Together, this and other studies suggest that RNAi machinery expression may affect key pathways in tumorigenesis and cancer biology. Understanding alterations in the functional RNAi machinery is of fundamental importance as we strive to develop novel therapies using RNAi strategies.
Selection of physicians for fellowships in obstetrics and gynecology subspecialties has become increasingly competitive. The number and quality of research publications is an important factor in the selection process. We sought to estimate the incidence of unverifiable (“ghost”) publications among gynecologic oncology fellowship applicants.
We reviewed the applications to a single gynecologic oncology fellowship program during 2004–2008. Articles and book chapters reported as published, “in press”, “submitted”, or “in progress” were systematically searched for by three reviewers using PubMed and Google. Chi-square analysis was used to evaluate associations between demographic factors and unverifiable publications.
Two hundred forty-three applications met the inclusion criteria. Of the 35 applicants who listed membership in Alpha Omega Alpha, 4 (11%) were not listed on the organization’s website as inductees. Of the 464 articles reported as published or “in press”, only 387 (83%) could be verified. Of the 148 applicants who reported at least 1 published/“in press” article, 44 (30%) had at least 1 unverifiable publication. On multivariable analysis, only male gender increased the likelihood of unverifiable publications (OR 2.1, 95% CI 1.1–4.1). Of the 282 manuscripts reported as “submitted” or “in progress”, only 126 (44%) were published. Of the 124 applicants who reported at least 1 “submitted”/“in progress” manuscript, 88 (71%) had at least 1 unverifiable manuscript.
The proportion of unverifiable publications listed on gynecologic oncology fellowship applications is concerning. Stringent review of applications before interview invitations and match list submission is warranted.
OPCML, frequently inactivated in ovarian tumors, mediates its anti-tumor effect via binding to the extracellular domains of several important oncogenic receptor tyrosine kinases (RTKs). This, in turn, leads to the down-regulation of RTKs in tumor cells and results in significant inhibition of tumor growth.
Chronic pain is a major clinical problem, yet the mechanisms underlying the transition from acute to chronic pain remain poorly understood. In mice, reduced expression of GPCR kinase 2 (GRK2) in nociceptors promotes cAMP signaling to the guanine nucleotide exchange factor EPAC1 and prolongs the PGE2-induced increase in pain sensitivity (hyperalgesia). Here we hypothesized that reduction of GRK2 or increased EPAC1 in dorsal root ganglion (DRG) neurons would promote the transition to chronic pain. We used 2 mouse models of hyperalgesic priming in which the transition from acute to chronic PGE2-induced hyperalgesia occurs. Hyperalgesic priming with carrageenan induced a sustained decrease in nociceptor GRK2, whereas priming with the PKCε agonist ΨεRACK increased DRG EPAC1. When either GRK2 was increased in vivo by viral-based gene transfer or EPAC1 was decreased in vivo, as was the case for mice heterozygous for Epac1 or mice treated with Epac1 antisense oligodeoxynucleotides, chronic PGE2-induced hyperalgesia development was prevented in the 2 priming models. Using the CFA model of chronic inflammatory pain, we found that increasing GRK2 or decreasing EPAC1 inhibited chronic hyperalgesia. Our data suggest that therapies targeted at balancing nociceptor GRK2 and EPAC1 levels have promise for the prevention and treatment of chronic pain.
Epithelial ovarian cancer is the leading cause of gynecologic cancer deaths. Most patients respond initially to platinum-based chemotherapy after surgical debulking, however relapse is very common and ultimately platinum resistance emerges. Understanding the mechanism of tumor growth, metastasis and drug resistant relapse will profoundly impact the therapeutic management of ovarian cancer.
Using patient tissue microarray (TMA), in vitro and in vivo studies we report a role of of cystathionine-beta-synthase (CBS), a sulfur metabolism enzyme in ovarian carcinoma. We report here that the expression of cystathionine-beta-synthase (CBS), a sulfur metabolism enzyme, is common in primary serous ovarian carcinoma. The in vitro effects of CBS silencing can be reversed by exogenous supplementation with the GSH and H2S producing chemical Na2S. Silencing CBS in a cisplatin resistant orthotopic model in vivo by nanoliposomal delivery of CBS siRNA inhibits tumor growth, reduces nodule formation and sensitizes ovarian cancer cells to cisplatin. The effects were further corroborated by immunohistochemistry that demonstrates a reduction of H&E, Ki-67 and CD31 positive cells in si-RNA treated as compared to scrambled-RNA treated animals. Furthermore, CBS also regulates bioenergetics of ovarian cancer cells by regulating mitochondrial ROS production, oxygen consumption and ATP generation. This study reports an important role of CBS in promoting ovarian tumor growth and maintaining drug resistant phenotype by controlling cellular redox behavior and regulating mitochondrial bioenergetics.
The present investigation highlights CBS as a potential therapeutic target in relapsed and platinum resistant ovarian cancer.
The translationally controlled tumor protein (TCTP) plays a role in cell growth, cell cycle and cancer progression. TCTP controls negatively the stability of the p53 tumor suppressor protein and interacts with the cellular cytoskeleton. The deregulation of the actin and cytokeratin cytoskeleton is responsible for the increased migratory activity of tumor cells and is linked with poor patient outcome. Recent studies indicate that the cyclin A- a key regulator of cell cycle controls actin organization and negatively regulates cell motility via regulation of RhoA expression. We studied the organization of actin and cytokeratin cytoskeleton and the expression of TCTP, p53, cyclin A, RhoA and actin in HIO180 non-transformed ovarian epithelial cells, and OVCAR3 and SKOV3 (expressing low level of inducible p53) ovarian epithelial cancer cells with different metastatic potential. Immunostaining and ultrastructural analyses illustrated a dramatic difference in the organization of the cytokeratin and actin filaments in non-transformed versus cancer cell lines. We also determined that there is an inverse correlation between the level of TCTP/RhoA and actin/p53/cyclin A expression in ovarian cancer cells. This previously unidentified negative relationship between TCTP/RhoA and actin/p53/cyclin A may suggest that this interaction is linked with the high aggressiveness of ovarian cancers.
TCTP; p53; actin; cytokeratin; ovarian cancer
Pro-inflammatory cytokines, such as interleukin-6 (IL-6), have been implicated in the underlying processes contributing to sleep regulation and fatigue. Despite evidence for sleep difficulties, fatigue, and elevations in IL-6 among women with ovarian cancer, the association between these symptoms and IL-6 has not been investigated. To address this knowledge gap, we examined relationships between sleep disturbance, fatigue, and plasma IL-6 in 136 women with ovarian cancer prior to surgery. These relationships were also examined in 63 of these women who were disease-free and not receiving chemotherapy one year post-diagnosis. At both time-points, higher levels of IL-6 were significantly associated with sleep disturbances (p < .05), controlling for potentially confounding biological and psychosocial covariates. Higher IL-6 was significantly associated with fatigue prior to surgery (p < .05); however, when sleep disturbance was included in the model, the relationship was no longer significant. IL-6 was not significantly associated with fatigue at one year. Changes in sleep over time were significantly associated with percent change in IL-6 from pre-surgery to one year, adjusting for covariates (p < .05). These findings support a direct association of IL-6 with sleep disturbances in this population, whereas the relationship between IL-6 and fatigue prior to surgery may be mediated by poor sleep. As this study is the first to examine cytokine contributions to sleep and fatigue in ovarian cancer, further research is warranted to clarify the role of biological correlates of sleep and fatigue in this population.
Sleep; Ovarian Cancer; Interleukin-6; Cancer; Fatigue; Circadian rhythm; Sickness Behaviors
Transcription factors are direct effectors of altered signaling pathways in cancer and frequently determine clinical outcomes in cancer patients. To uncover new transcription factors that would determine clinical outcomes in breast cancer, we systematically analyzed gene expression data from breast cancer patients. Our results revealed that Forkhead box protein M1 (FOXM1) is the top-ranked survival-associated transcription factor in patients with triple-negative breast cancer. Surprisingly, silencing FOXM1 expression led breast cancer cells to become more sensitive to doxorubicin (Dox). We found that FOXM1-dependent resistance to Dox is mediated by regulating DNA repair genes. We further demonstrated that NFκB1 interacts with FOXM1 in the presence of Dox to protect breast cancer cells from DNA damage. Finally, silencing FOXM1 expression in breast cancer cells in a mouse xenograft model significantly sensitized the cells to Dox. Our systematic approaches identified an unexpected role of FOXM1 in Dox resistance by regulating DNA repair genes, and our findings provide mechanistic insights into how FOXM1 mediates resistance to Dox and evidence that FOXM1 may be a promising therapeutic target for sensitizing breast cancer cells to Dox.
Vascular endothelial growth factor (VEGF) plays a critical role in angiogenesis, which is required for tumor growth and metastasis. In this article, a review of the functional and biological roles of the VEGF pathway in driving angiogenesis and growth of gynecologic malignancies was performed. Based on the biological functions of VEGF, multiple approaches for targeting the VEGF/VEGF-receptor complex have been developed and many of these have demonstrated substantial activity in preclinical models. These promising data have led to rapid clinical development of VEGF-targeted agents. Therefore, we also assessed the status of VEGF-targeted therapies and associated toxicities in gynecologic malignancies. However, many questions remain related to optimal dosing, sequencing of therapies, management of toxicities, appropriate patient selection, and assessment of response, which will require further studies. Nevertheless, VEGF-targeted therapies offer hope for improving the outcome of cancer patients.
Vascular endothelial growth factor (VEGF); angiogenesis; gynecologic cancer
Tumor development and progression are inherently dependent on the process of angiogenesis. Recently, anti-angiogenic therapy has started to show promise as an effective treatment strategy in many solid tumors including ovarian carcinoma. Unfortunately, lack of effective biomarkers presents a challenge for oncologists in treatment planning as well as monitoring response of new anti-vascular agents. Previously, quantification of angiogenesis by microvessel density analysis provided useful prognostic information, however, its utility following anti-angiogenic therapy remains to be determined. Moreover, since secreted cytokines play an active part in angiogenesis by mediating neovascularization in tumors, investigations have focused on their potential role to serve as candidate biomarkers of disease detection, prognosis, and treatment response. In this article, we review the role of key angiogenesis markers as potential biomarkers in ovarian carcinoma.
Angiogenesis; biomarker; ovarian carcinoma; therapy
Photothermal ablation (PTA) is an emerging technique that uses near-infrared laser light-generated heat to destroy tumor cells. However, complete tumor eradication by PTA therapy alone is difficult because heterogeneous heat distribution can lead to sub-lethal thermal dose in some areas of the tumor. Successful PTA therapy requires selective delivery of photothermal conducting nanoparticles to mediate effective PTA of tumor cells, and the ability to combine PTA with other therapy modalities. Here, we synthesized multifunctional doxorubicin (DOX)-loaded hollow gold nanospheres (DOX@HAuNS) that target EphB4, a member of the Eph family of receptor tyrosine kinases overexpressed on the cell membrane of multiple tumors and angiogenic blood vessels. Increased uptake of targeted nanoparticles T-DOX@HAuNS was observed in three EphB4-positive tumors both in vitro and in vivo. In vivo release of DOX from DOX@HAuNS, triggered by near-infrared laser, was confirmed by dual radiotracer technique. Treatment with T-DOX@HAuNS followed by near-infrared laser irradiation resulted in significantly decreased tumor growth when compared to treatments with non-targeted DOX@HAuNS plus laser or HAuNS plus laser. The tumors in six of the eight mice treated with T-DOX@HAuNS plus laser regressed completely with only residual scar tissue by 22 days following injection, and none of the treatment groups experienced a loss in body weight. Together, our findings demonstrate that concerted chemo-photothermal therapy with a single nanodevice capable of mediating simultaneous PTA and local drug release may have promise as a new anticancer therapy.
Hollow Gold Nanospheres; EphB4 receptors; Targeting; Doxorubicin; Multimodal Therapy
p53 plays an important role in mitotic checkpoint, but what its role is remains enigmatic. Aurora A is a Ser/Thr kinase involved in correcting progression of mitosis. Here, we show that p53 is a negative regulator for Aurora A. We found that p53 deficiency leads to Aurora A elevation. Ectopic expression of p53 or DNA damage-induced expression of p53 can suppress the expression of Aurora A. Mechanistic studies show that p53 is a negative regulator for Aurora A expression through both transcriptional and posttranslational regulation. p53 knockdown in cancer cells reduces the level of p21, which, in turn, increases the activity of CDK2 followed by induction of Rb1 hyperphosphorylation and its dissociation with transcriptional factor E2F3. E2F3 can bind to Aurora A gene promoter, potentiating Aurora A gene expression and p53 deficiency, enhancing the binding of E2F3 on Aurora A promoter. Also, p53 deficiency leads to decelerating Aurora A’s turnover rate, due to the fact that p53 deficiency causes the downregulation of Fbw7α, a component of E3 ligase of Aurora A. Consistently, p53 knockdown-mediated Aurora A elevation is mitigated when Fbw7α is ectopically expressed. Thus, p53-mediated Aurora A degradation requires Fbw7α expression. Significantly, inverse correlation between p53 and Aurora A elevation is translated into the deregulation of centrosome amplification. p53 knockdown leads to high percentages of cells with abnormal amplification of centrosome. These data suggest that p53 is an important negative regulator of Aurora A, and that loss of p53 in many types of cancer could lead to abnormal elevation of Aurora A and dysregulated mitosis, which provides a growth advantage for cancer cells.
cell cycle; gammaH2AX; human non-small cell lung carcinoma; mTOR; metronomic chemotherapy; oncogenes; personalized cancer treatment
Aurora kinases are essential for regulation of chromosome segregation and cytokinesis during mitosis and play a role in growth and progression of human tumors, including ovarian cancer. Aurora A and Aurora B are frequently overexpressed in high-grade and low-grade ovarian cancers. Targeting Aurora kinases has great potential for improving the efficacy of chemotherapies of ovarian cancer. In this study, we investigated whether the Aurora kinase inhibitor, VE 465, can enhance the anti-tumor activity of carboplatin in human ovarian cancer cells. The antitumor activity of VE 465 was tested by MTT proliferative assay in multiple established human epithelial ovarian cancer cell lines of varying p53 status. VE 465 and carboplatin had a synergistic effect on cell viability in both platinum-sensitive and -resistant ovarian cancers. The growth-inhibitory effect was accompanied by reduction in expression of histone 3 and an increase in apoptosis. We conclude that VE 465 enhances the efficacy of carboplatin agents in ovarian carcinoma.
ovarian cancer; Aurora kinases; Aurora kinase inhibitors; chemosensitization
Gynecologic cancer is a major burden in both developed and developing countries. Almost a half million deaths from gynecologic cancer are reported each year. Understanding the molecular biology of cancer is a principle resource leading to the identification of new potential therapeutic targets, which may be parlayed into novel therapeutic options in gynecologic cancer. Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase, which plays a pivotal role in many aspects of malignant growth including cancer cell survival, migration, invasion, angiogenesis and metastasis. Various human cancer tissues have demonstrated high expression of FAK or activated FAK, which has been correlated with survival of cancer patients. Among gynecologic cancers, reports have emerged demonstrating that FAK is involved in the pathogenesis of ovarian, endometrial, and cervical cancers. In addition, the polycomb group protein enhancer of Zeste homologue 2 (EZH2), Dll4/notch and EphA2 has also emerged as important regulators of endothelial cell biology and angiogenesis. Herein, we review the role of these new targets in tumor angiogenesis and the rationale for further clinical development.
Focal adhesion kinase; EZH2; Dll4/notch; ovarian cancer; uterine cancer; cervix cancer; angiogenesis; endothelial cells
Previous research has demonstrated relationships of social support with disease-related biomarkers in patients with ovarian cancer. However, the clinical relevance of these findings to patient outcomes has not been established. This prospective study examined how social support relates to long-term survival among consecutive patients with ovarian cancer. We focused on two types of social support: social attachment, a type of emotional social support reflecting connections with others, and instrumental social support reflecting the availability of tangible assistance.
Patients and Methods
Patients were prospectively recruited during a presurgical clinic visit and completed surveys before surgery. One hundred sixty-eight patients with histologically confirmed epithelial ovarian cancer were observed from the date of surgery until death or December 2010. Clinical information was obtained from medical records.
In a Cox regression model, adjusting for disease stage, grade, histology, residual disease, and age, greater social attachment was associated with a lower likelihood of death (hazard ratio [HR], 0.87; 95% CI, 0.77 to 0.98; P = .018). The median survival time for patients with low social attachment categorized on a median split of 15 was 3.35 years (95% CI, 2.56 to 4.15 years). In contrast, by study completion, 59% of patients with high social attachment were still alive after 4.70 years. No significant association was found between instrumental social support and survival, even after adjustment for covariates.
Social attachment is associated with a survival advantage for patients with ovarian cancer. Clinical implications include the importance of screening for deficits in the social environment and consideration of support activities during adjuvant treatment.