We investigated the functional effects of microRNA-34a (miR-34a) on c-Myc transcriptional complexes in renal cell carcinoma. miR-34a down-regulated expression of multiple oncogenes including c-Myc by targeting its 3′ untranslated region, which was revealed by luciferase reporter assays. miR-34a was also found to repress RhoA expression by suppressing the c-Myc–Skp2–Miz1 transcriptional complex that activates RhoA. Overexpression of c-Myc reversed miR-34a suppression of RhoA expression and inhibition of cell invasion, suggesting that miR-34a inhibits invasion by suppressing RhoA through c-Myc. miR-34a was also found to repress the c-Myc–P-TEFb transcription elongation complex, indicating one of the mechanisms by which miR-34a has profound effects on cellular functions. Our results demonstrate that miR-34a suppresses assembly and function of the c-Myc complex that activates or elongates transcription, indicating a novel role of miR-34a in the regulation of transcription by c-Myc.
Recently miR-182 has been reported to be over-expressed in prostate cancer (PC) tissues, however detailed functional analysis of miR-182-5p has not been carried out. The purpose of this study was to: 1. analyze the function of miR-182-5p in prostate cancer, 2. assess its usefulness as a tumor marker, 3. identify miR-182-5p target genes in PC, 4. investigate the potential for miR-182-5p inhibitor to be used in PC treatment. Initially we found that miR-182-5p expression was significantly higher in prostate cancer tissues and cell lines compared to normal prostate tissues and cells. Moreover high miR-182-5p expression was associated with shorter overall survival in PC patients. To study the functional significance of miR-182-5p, we knocked down miR-182-5p with miR-182-5p inhibitor. After miR-182-5p knock-down, prostate cancer cell proliferation, migration and invasion were decreased. We identified FOXF2, RECK and MTSS1 as potential target genes of miR-182-5p using several algorithms which was confirmed by 3’UTR luciferase assay and Western analysis. Knock-down of miR-182-5p also significantly decreased in vivo prostate tumor growth. In conclusion this is the first report documenting that over-expression of miR-182-5p is associated with prostate cancer progression and potentially useful as a prognostic biomarker. Also knock down of miR-182-5p in order to increase expression of tumor suppressor genes FOXF2, RECK and MTSS1 may be of therapeutic benefit in prostate cancer treatment.
Onco-miR-182-5p has been reported to be over-expressed in bladder cancer (BC) tissues however a detailed functional analysis of miR-182-5p has not been carried out in BC. Therefore the purpose of this study was to: 1. conduct a functional analysis of miR-182-5p in bladder cancer, 2. assess its usefulness as a tumor marker, 3. identify miR-182-5p target genes in BC. Initially we found that miR-182-5p expression was significantly higher in bladder cancer compared to normal tissues and high miR-182-5p expression was associated with shorter overall survival in BC patients. To study the functional significance of miR-182-5p, we over-expressed miR-182-5p with miR-182-5p precursor and observed that cell proliferation, migration and invasion abilities were increased in BC cells. However cell apoptosis was inhibited by miR-182-5p. We also identified Smad4 and RECK as potential target genes of miR-182-5p using several algorithms. 3′UTR luciferase activity of these target genes was significantly decreased and protein expression of these target genes was significantly up-regulated in miR-182-5p inhibitor transfected bladder cancer cells. MiR-182-5p also increased nuclear beta-catenin expression and while Smad4 repressed nuclear beta-catenin expression. In conclusion, our data suggests that miR-182-5p plays an important role as an oncogene by knocking down RECK and Smad4, resulting in activation of the Wnt-beta-catenin signaling pathway in bladder cancer.
miR-23b is located on chromosome number 9 and plays different roles in different organs especially with regards to cancer development. However, the functional significance of miR-23b-3p in renal cell carcinoma (RCC) has not been reported.
Methods and Results
We measured miR-23b-3p levels in 29 pairs of renal cell carcinoma and their normal matched tissues using real-time PCR. The expression level of miR-23b-3p was correlated with the 5 year survival rate of renal cancer patients. In 15 cases (52%), miR-23b-3p expression was found to be high. All patients with moderate to low miR-23b-3p expression survived 5 years, while those with high miR-23b-3p expression, only 50% survived. After knocking down miRNA-23b-3p expression in RCC cell lines, there was an induction of apoptosis and reduced invasive capabilities. MiR-23b-3p was shown to directly target PTEN gene through 3′UTR reporter assays. Inhibition of miR-23b-3p induces PTEN gene expression with a concomitant reduction in PI3-kinase, total Akt and IL-32. Immunohistochemistry showed the lack of PTEN protein expression in cancerous regions of tissue samples where the expression of miR-23b-3p was high. We studied the in vitro effects of the dietary chemo preventive agent genistein on miR-23b-3p expression and found that it inhibited expression of miR-23b-3p in RCC cell lines.
The current study shows that miR-23b-3p is an oncogenic miRNA and inhibits PTEN tumor suppressor gene in RCC. Therefore, inhibition of miR-23b-3p may be a useful therapeutic target for the treatment of renal cell carcinoma.
MicroRNAs (miRNAs) are non-protein-coding sequences that can function as oncogenes or tumor suppressor genes. This study documents the tumor suppressor role of miR-1280 in bladder cancer. Quantitative real-time PCR and in situ hybridization analyses showed that miR-1280 is significantly down-regulated in bladder cancer cell lines and tumors compared to a non-malignant cell line or normal tissue samples. To decipher the functional significance of miR-1280 in bladder cancer, we ectopically over-expressed miR-1280 in bladder cancer cell lines. Over-expression of miR-1280 had antiproliferative effects and impaired colony formation of bladder cancer cell lines. FACS (fluorescence activated cell sorting) analysis revealed that re-expression of miR-1280 in bladder cancer cells induced G2-M cell cycle arrest and apoptosis. Our results demonstrate that miR-1280 inhibited migration and invasion of bladder cancer cell lines. miR-1280 also attenuated ROCK1 and RhoC protein expression. Luciferase reporter assays demonstrated that oncogene ROCK1 is a direct target of miR-1280 in bladder cancer. This study also indicates that miR-1280 may be of diagnostic and prognostic importance in bladder cancer. For instance, ROC analysis showed that miR-1280 expression can distinguish between malignant and normal bladder cancer cases and Kaplan-Meier analysis revealed that patients with miR-1280 high expression had higher overall survival compared to those with low miR-1280 expression. In conclusion, this is the first study to document that miR-1280 functions as a tumor suppressor by targeting oncogene ROCK1 to invasion/migration and metastasis. Various compounds are currently being used as ROCK1 inhibitors; therefore restoration of tumor suppressor miR-1280 might be therapeutically useful either alone or in combination with these compounds in the treatment of bladder cancer.
Cyclic phosphatidic acid (1-acyl-sn-glycerol-2,3-cyclic phosphate; cPA) is a naturally occurring analog of lysophosphatidic acid (LPA) with a variety of distinctly different biological activities from those of LPA. In contrast to LPA, a potent inducer of tumor cell invasion, palmitoyl-cPA inhibits FBS- and LPA-induced transcellular migration and metastasis. To prevent the conversion of cPA to LPA we synthesized cPA derivatives by stabilizing the cyclic phosphate ring; to prevent the cleavage of the fatty acid we generated alkyl ether analogs of cPA. Both sets of compounds were tested for inhibitory activity on transcellular tumor cell migration. Carba derivatives, in which the phosphate oxygen was replaced with a methylene group at either the sn-2 or the sn-3 position, showed much more potent inhibitory effects on MM1 tumor cell transcellular migration and the pulmonary metastasis of B16-F0 melanoma than the natural pal-cPA. The antimetastatic effect of carba-cPA was accompanied by the inhibition of RhoA activation and was not due to inhibition of the activation of LPA receptors.
Cyclic phosphatidic acid; Lysophosphatidic acid; LPA; Invasion; Metastasis
Pituicytoma is a rare neoplasm of the neurohypophysis. To the best of our knowledge there have been no reports of pituicytoma in which long-term magnetic resonance imaging observation was performed. We calculated the doubling time of the tumor volume and described the growth pattern of a pituicytoma.
A 52-year-old Japanese man with a history of decreased libido was found to have a sellar and suprasellar mass. He underwent transsphenoidal surgery, but only a small specimen was obtained because of intraoperative bleeding. The tentative histological diagnosis was schwannoma. He noticed bitemporal hemianopsia 7 years later. A follow-up magnetic resonance imaging disclosed a tumor volume doubling time of 3830 days. Transcranial gross-total tumor resection was performed. The lesion consisted of elongated and plump tumor cells that were arranged in a fascicular or storiform pattern and were positive for S-100 protein and focally positive for glial fibrillary acidic protein. The final histological diagnosis was pituicytoma.
Pituicytoma is a slow-growing tumor, but the growth rate may change during follow-up.
Neurohypophysis; Pituicyte; Pituicytoma; Tumor volume doubling time
Genistein has been shown to suppress the growth of several cancers through modulation of various pathways. However, the effects of genistein on the regulation of oncogenic microRNA-151 (miR-151) have not been reported. In this study, we investigated whether genistein could alter the expression of oncogenic miR-151 and its target genes that are involved in the progression and metastasis of prostate cancer (PCa). Real-time RT-PCR showed that the expression of miR-151 was higher in PC3 and DU145 cells compared with RWPE-1 cells. Treatment of PC3 and DU145 cells with 25 µM genistein down-regulated the expression of miR-151 compared with vehicle control. Inhibition of miR-151 in PCa cells by genistein significantly inhibited cell migration and invasion. In-silico analysis showed that several genes (CASZ1, IL1RAPL1, SOX17, N4BP1 and ARHGDIA) suggested to have tumor suppressive functions were target genes of miR-151. Luciferase reporter assays indicated that miR-151 directly binds to specific sites on the 3′UTR of target genes. Quantitative real-time PCR analysis showed that the mRNA expression levels of the five target genes in PC3 and DU145 were markedly changed with miR-151 mimics and inhibitor. Kaplan-Meier curves and log-rank tests revealed that high expression levels of miR-151 had an adverse effect on survival rate. This study suggests that genistein mediated suppression of oncogenic miRNAs can be an important dietary therapeutic strategy for the treatment of PCa.
MiR-145 is downregulated in various cancers including prostate cancer. However, the underlying mechanisms of miR-145 downregulation are not fully understood. Here, we reported that miR-145 was silenced through DNA hypermethylation and p53 mutation status in laser capture microdissected (LCM) prostate cancer and matched adjacent normal tissues. In 22 of 27 (81%) prostate tissues, miR-145 was significantly downregulated in the cancer compared with the normal tissues. Further studies on miR-145 downregulation mechanism showed that miR-145 is methylated at the promoter region in both prostate cancer tissues and 50 different types of cancer cell lines. In seven cancer cell lines with miR-145 hypermethylation, 5-aza-2′-deoxycytidine treatment dramatically induced miR-145 expression. Interestingly, we also found a significant correlation between miR-145 expression and the status of p53 gene in both LCM prostate tissues and 47 cancer cell lines. In 29 cell lines with mutant p53, miR-145 levels were downregulated in 28 lines (97%), whereas in 18 cell lines with wild-type p53 (WT p53), miR-145 levels were downregulated in only 6 lines (33%, P < 0.001). Electrophoretic mobility shift assay showed that p53 binds to the p53 response element upstream of miR-145, but the binding was inhibited by hypermethylation. To further confirm that p53 binding to miR-145 could regulate miR-145 expression, we transfected WT p53 and MUT p53 into PC-3 cells and found that miR-145 is upregulated by WT p53 but not with MUTp53. The apoptotic cells are increased after WT p53 transfection. In summary, this is the first report documenting that downregulation of miR-145 is through DNA methylation and p53 mutation pathways in prostate cancer.
MicroRNA-21 is up-regulated in a variety of cancers like, breast, colorectal, lung, head and neck etc. However, the regulation of miR-21 in renal cell carcinoma (RCC) has not yet been studied systematically.
Methods and Results
We measured miR-21 levels in 54 pairs of kidney cancers and their normal matched tissues by real-time PCR. The expression level of miR-21 was correlated with 5 year survival and the pathological stage. Functional studies were done after inhibiting miR-21 in RCC cell lines. We studied in vitro and in vivo effects of the chemo preventive agent genistein on miR-21 expression. In 48 cases (90%), miR-21 was increased. All patients with low miR-21 expression survived 5 years, while with high miR-21 expression, only 50% survived. Higher expression of miR-21 is associated with an increase in the stage of renal cancer. Functional studies after inhibiting miRNA-21 in RCC cell lines show cell cycle arrest, induction of apoptosis and reduced invasive and migratory capabilities. Western blot analysis showed an increase in the expression of p21 and p38 MAP kinase genes and a reduction in cyclin E2. Genistein inhibited the expression of miR-21 in A-498 cells and in the tumors formed after injecting genistein treated A-498 cells in nude mice besides inhibiting tumor formation.
The current study shows a clear correlation between miR-21 expression and clinical characteristics of renal cancer. Thus we believe that miR-21 can be used as a tumor marker and its inhibition may prove to be useful in controlling cancers with up-regulated miR-21.
BTG3/ANA/APRO4 has been reported to be a tumor suppressor gene in some malignancies. It constitutes important negative regulatory mechanism for Src-mediated signaling, a negative regulator of the cell cycle and inhibits transcription factor E2F1. We report that BTG3 is downregulated in renal cancer and that the mechanism of inactivation is through promoter hypermethylation. Quantitative real-time polymerase chain reaction (PCR) showed that BTG3 was downregulated in cancer tissues and cells. Genistein and 5-aza-2′-deoxycytidine (5Aza-C) induced BTG3 messenger RNA (mRNA) expression in A498, ACHN and HEK-293 renal cell carcinoma (RCC) cell lines. Bisulfite-modified PCR and DNA sequencing results showed complete methylation of BTG3 promoter in tumor samples and cancer cell lines. Genistein and 5Aza-C treatment significantly decreased promoter methylation, reactivating BTG3 expression. Chromatin immunoprecipitation assay revealed that genistein and 5Aza-C increased levels of acetylated histones 3, 4, 2H3K4, 3H3K4 and RNA polymerase II at the BTG3 promoter indicative of active histone modifications. Enzymatic assays showed genistein and 5Aza-C decreased DNA Methyltransferase, methyl-CpG-binding domain 2 activity and increased HAT activity. Cell cycle and 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide cell proliferation assays showed that genistein has antiproliferative effect on cancer cell growth through induction of cell cycle arrest. This is the first report to show that BTG3 is epigenetically silenced in RCC and can be reactivated by genistein-induced promoter demethylation and active histone modification. Genistein had similar effects to that of 5Aza-C, which is a potent demethylating agent with high toxicity and instability. Genistein being a natural, non-toxic, dietary isoflavone is effective in retarding the growth of RCC cells, making it a promising candidate for epigenetic therapy in renal carcinoma.
Stimulation of C3H 10T1/2 murine fibroblasts with interferon-γ(IFN) and bacterial lipopolysaccharide (LPS) generates reactive oxygen and nitrogen species leading to DNA damage, lipid oxidation, and tocopherol oxidation. The tocopherols possess unique chemical and biological properties that suggest they have important roles related to intracellular defense against radical-mediated damage.
Despite increased levels of reactive oxidants and decreased media tocopherol, cellular levels of γ-tocopherol, but not α-tocopherol, were observed to increase significantly when cells were treated with IFN/LPS. Inhibition of nitric oxide (NO) synthesis by a specific inhibitor of inducible NO synthase (iNOS) increased both intracellular α-tocopherol and γ-tocopherol concentrations, but did not significantly alter the reduction in media tocopherol levels caused by IFN/LPS treatment. Both exposure to exogenous NO and cellular synthesis of NO in cell culture increased media levels of 8-epi-prostaglandin F2α, a marker of oxidative lipid damage, whereas inhibition of endogenous NO synthesis reduced media 8-epi-prostaglandin F2α formation to control levels.
Elevated intracellular levels of γ-tocopherol in response to the cellular inflammatory state may indicate that it serves a unique role in minimizing cellular damage resulting from endogenous NO synthesis. Results of the current study suggest that NO is an important mediator of damage within the cell, as well as in the oxidation of both α- and γ-tocopherols. The paradoxical increase in cellular tocopherol associated with the induction of NO synthesis may indicate either enhanced cellular transport/decreased export for tocopherols or recruitment of free tocopherol from tocopherol storage molecules.