Increased Prostate Cancer Cell Proliferation Research Articles

Has_circ_0070512 promotes prostate cancer progression by regulating the miR-338-3p/hedgehog signaling pathway.

Circular RNAs (circRNAs) are a type of non-coding RNA that plays a vital role in biology. circRNAs appear to have a role in the development and progression of several malignancies, according to research. However, circRNAs that regulate prostate cancer (PCa) progression are still largely unknown and deserve further exploration. The aim of this study was to investigate the effect of hsa_circ_0070512 on the function and mechanism of PCa. hsa_circ_0070512 was increased in PCa tissues and cells and was mostly found in the cytoplasm of PCa cells. Overexpression of hsa_circ_0070512 considerably increased PCa cell proliferation and migration, whereas silencing of hsa_circ_0070512 greatly decreased PCa cell proliferation and migration. Mechanistically, we show that hsa_circ_0070512 acts as a "molecular sponge" for miR-338-3p and that the miR-338-3p mimics partially block the pro-tumor effects of hsa_circ_0070512. RNA sequencing analysis of PC3 cells stably overexpressing hsa_circ_0070512 revealed that hedgehog was downstream of the signaling pathways of hsa_circ_0070512 and miR-338-3p. Our results implied that hsa_circ_0070512 regulated the hedgehog signaling pathways through miR-338-3p to enhance PCa growth and migration, providing a new diagnostic and therapeutic target for PCa.

MicroRNA‑301a‑3p overexpression promotes cell invasion and proliferation by targeting runt‑related transcription factor 3 in prostate cancer.

MicroRNAs (miRNAs) are known to serve a role in tumorigenic programs. The dysregulated expression of miR‑301a‑3p may affect the progression of various types of human cancer; however, the expression and the role of miR‑301a‑3p in prostate cancer are still unclear. The present study aimed to clarify the role and molecular mechanism of miR‑301a‑3p in prostate cancer. The results demonstrated that the expression of miR‑301a‑3p was significantly upregulated in human prostate cancer tissues and in several prostate cancer cell lines. Invitro overexpression of miR‑301a‑3p notably increased prostate cancer cell proliferation and invasion. Bioinformatics analysis revealed that runt‑related transcription factor 3 (RUNX3) may be a target of miR‑301a‑3p, which was confirmed by Dual‑luciferase reporter assay. Western blot analysis also demonstrated that miR‑301a‑3p regulated the protein expression levels of RUNX3. In addition, the results indicated that miR‑301a‑3p may regulate the Wnt signaling pathway, and rescue experiments indicated that RUNX3 contributed to the effects of miR‑301a‑3p on cell proliferation and invasion through Wnt signaling. In conclusion, these findings suggested that miR‑301a‑3p may promote prostate cancer cell invasion and proliferation by targeting RUNX3, and provided insight into understanding prostate cancer pathogenesis. miR‑301a‑3p may be a potential therapeutic candidate to treat prostate cancer.

SNORA42 enhances prostate cancer cell viability, migration and EMT and is correlated with prostate cancer poor prognosis.

Prostate cancer (PCa) is one of the most common invasive cancers and the second leading cause of cancer-related death in male worldwide, reflecting the needs of diagnostic and prognostic biomarkers for PCa. Emerging evidence has revealed small nucleolar RNAs (snoRNAs) playing a significant role in tumorigenesis and cancer progression. However, there are few reports about snoRNAs in PCa. Here, we found SNORA42 rather than its host gene (KIAA0907) was up-regulated in PCa cell lines. Meanwhile, an obvious up-regulation of SNORA42 was observed in cancer tissues compared to their adjacent normal tissues. SNORA42 could be induced by DHT stimulation. Over-expression of SNORA42 increased prostate cancer cell proliferation and inhibited apoptosis. Importantly, SNORA42 increased prostate cancer cell migration and invasion. Higher SNORA42 expression level was found to be correlated with shorter survival in metastatic PCa tissues by Kaplan-Meier survival analysis, but this effect was not found in primary PCa tissues. In conclusion, over-expression of SNORA42 could have an oncogenic effect on the progression of PCa. SNORA42 might serve as a prognostic biomarker in PCa.

Abstract 4476: A novel nonsense mutation in androgen receptor confers resistance to CYP17 inhibitor treatment in prostate cancer

Abstract Background: The standard treatment for prostate cancer (PCa) is androgen deprivation therapy (ADT) that blocks AR transcriptional activity, which is responsible to the initiation and progression of PCa. However, ADT invariably leads to the castration-resistant PCa (CRPC) with restored activity of AR. CRPC can be further treated with more intensive ADTs, including CYP17-inhibitors to block intratumoral androgen synthesis and more potent AR antagonist. By analyzing the tumor mRNA from a CRPC patient biopsy who developed resistance to CYP17-inhibitor treatment, we identified a novel nonsense AR mutation on ligand binding domain (Q784*), which produces a C-terminal truncated form of AR protein containing only a fraction of ligand binding domain (LBD) and may mimic the function of some AR splice variants. We hypothesized that AR-Q784* may gain the androgen-independent activity, or may enhance the transcriptional activity of full-length AR (AR-FL) under low androgen environment through dimerization with AR-FL. Method: Luciferase reporter assays were applied to assess the transcriptional activity of AR-Q784* in absence or presence of androgens, and with or without AR-FL. Immunoblotting and immunofluorescence assays were used to examine the protein stability and cellular localization of AR-Q784*. Chromatin immunoprecipitation assays were also used to assess the chromatin binding ability of AR-Q784*. Moreover, the stable cell line that expresses endogenous AR-FL and tetracycline-inducible AR-Q784* was generated to determine the transcription activity on AR target genes and assess the effects on cell proliferation, particularly under low dose androgen condition. Result: Although it was constitutively expressed in nucleus, AR-Q784* does not elicit transcriptional activity despite the conditions of ligands. However, when it was co-expressed with AR-FL, AR-Q784* can enhance AR-mediated transcriptional activity and thus increased PCa cell proliferation particularly under low androgen conditions. Mechanistically, AR-Q784* can dimerize with AR-FL, enhance DNA binding ability of AR-FL, and strengthen AR recruitment of p300 coactivator. Conclusion: We show that CYP17 inhibitor treatment in CRPC may select for a distinct class of AR mutations/variations, including nonsense (AR-Q784*) or point-deletion mutations within LBD and certain splice variants that only lose a fraction of LBD domain. This class of AR mutants/variants is transcriptionally inactive but can enhance the activity of AR-FL due to their abilities of constitutive DNA binding and dimerization with AR-FL. However, this enhancing activity of those AR mutants/variants can be prevented by antagonist treatments such as enzalutamide. Therefore, this study provides an additional rationale for treating PCa patients with combination therapy of abiraterone and enzalutamide, which may prevent the selection for such AR mutations/variations in CRPC. Citation Format: Dong Han, Jude Owiredu, Kevin Valencia, Changmeng Cai. A novel nonsense mutation in androgen receptor confers resistance to CYP17 inhibitor treatment in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4476. doi:10.1158/1538-7445.AM2017-4476

Shp2 promotes metastasis of prostate cancer by attenuating the PAR3/PAR6/aPKC polarity protein complex and enhancing epithelial-to-mesenchymal transition.

Epithelial-to-mesenchymal transition (EMT), marked by the dissolution of cell-cell junctions, loss of cell polarity and increased cell motility, is one of the essential steps for prostate cancer metastasis. However, the underlying mechanism has not been fully explored. We report in this study that Shp2 is upregulated in prostate cancers and is associated with a poor disease outcome, namely tumor metastasis and shortened patient survival. Overexpression of wild-type Shp2 or an oncogenic Shp2 mutant leads to increased prostate cancer cell proliferation, colony and sphere formation, and in vivo tumor formation. Opposite effects are seen in Shp2-knockdown cells. Moreover, Shp2 promotes in vitro migration and in vivo metastasis of prostatic tumor cells. Mechanistically, Shp2 interacts with PAR3 (partitioning-defective 3) via its Src homology-2 domain. Ectopic expression of Shp2 attenuates the phosphorylation of PAR3 and the formation of the PAR3/PAR6/atypical protein kinase C polarity protein complex, resulting in disrupted cell polarity, dysregulated cell-cell junctions and increased EMT. These findings provide a novel mechanism by which oncogenic signal-transduction molecules regulate cell polarity and induction of EMT.

The RNA-binding protein hnRNPA2 regulates β-catenin protein expression and is overexpressed in prostate cancer

Introduction The RNA-binding protein hnRNPA2 (HNRNPA2B1) is upregulated in cancer, where it controls alternative pre-mRNA splicing of cancer-relevant genes. Cytoplasmic hnRNPA2 is reported in aggressive cancers, but is functionally uncharacterized. We explored the role of hnRNPA2 in prostate cancer (PCa). Methods: hnRNPA2 function/localization/expression in PCa was determined using biochemical approaches (colony forming/proliferation/luciferase reporter assays/flow cytometry/immunohistocytochemistry). Binding of hnRNPA2 within cancer-relevant 3′-UTR mRNAs was identified by bioinformatics. Results: RNAi-mediated knockdown of hnRNPA2 reduced colony forming and proliferation, while hnRNPA2 overexpression increased proliferation of PCa cells. Nuclear hnRNPA2 is overexpressed in high-grade clinical PCa, and is also observed in the cytoplasm in some cases. Ectopic expression of a predominantly cytoplasmic variant hnRNPA2-ΔRGG also increased PCa cell proliferation, suggesting that cytoplasmic hnRNPA2 may also be functionally relevant in PCa. Consistent with its known cytoplasmic roles, hnRNPA2 was associated with 3′-UTR mRNAs of several cancer-relevant mRNAs including β-catenin (CTNNB1). Both wild-type hnRNPA2 and hnRNPA2-ΔRGG act on CTNNB1 3′-UTR mRNA, increasing endogenous CTNNB1 mRNA expression and β-catenin protein expression and nuclear localization. Conclusion: Nuclear and cytoplasmic hnRNPA2 are present in PCa and appear to be functionally important. Cytoplasmic hnRNPA2 may affect the cancer cell phenotype through 3′-UTR mRNA-mediated regulation of β-catenin expression and other cancer-relevant genes.

Abstract 1974: Functional characterization of Basonuclin 1 (BNC1): a novel tumor suppressor gene commonly downregulated in human prostate cancer.

Abstract Prostate cancer (PCa) harbors a myriad of aberrant genomic and epigenetic alterations. Epigenetic inactivation of genes in PCa is largely based on transcriptional silencing by aberrant CpG methylation of CpG rich promoter regions. To better understand the role of aberrant methylation changes and to identify biological pathways likely to be affected in PCa, we used a genome-wide methylation array from Illumina (Infunium) to identify novel methylated genes associated to PCa. We identified several candidate genes including BNC1 as novel genes which are frequently methylated and whose methylation closely related to inactivation of gene expression in prostate cancer cell lines. Basonuclin1 is a zinc finger transcription factor that interacts with a subset of promoters of genes transcribed by both RNA polymerase-I and -II and has roles in maintaining ribosomal biogenesis and the proliferative potential of immature epithelial cells. We found that the expression of BNC1 negatively correlated with the degree of methylation at the CpG island in prostate tumor samples compared to benign prostate tissues. The forced-expression of BNC1 significantly decreased prostate cancer cell proliferation whereas the siRNA mediated BNC1 knock-down increased prostate cancer cell proliferation. Overall, our data suggest a potential tumor suppressor role for BNC1 that includes regulation of cell proliferation and cell-cell interaction in prostate carcinogenesis. Citation Format: Bernard Kwabi-Addo, Songping Wang, Paulett Furbert-Harris, Srinivasan Yegnasubramanian, Joseph Devaney. Functional characterization of Basonuclin 1 (BNC1): a novel tumor suppressor gene commonly downregulated in human prostate cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1974. doi:10.1158/1538-7445.AM2013-1974

Abstract 1917: Loss of steroid sulfotransferase (SULT) in human prostate cancer: Potential implications for SULT as a biomarker and therapeutic target.

Abstract Purpose: Reactivated androgen receptor, fueled by elevated tumor tissue 5α-dihydrotestosterone (DHT), plays a key role in the reemergence of prostate cancer. Primary prostate cancer almost always regresses in response to androgen deprivation therapy. The disease, however, recurs and progresses to therapy resistance and death in ∼30% patients. New-generation drugs that inhibit androgen receptor (MDV3100™) or enzymes involved in androgen biosynthesis (Zytiga™, TAK-700™, Dutasteride™) extend survival of post-chemotherapy patients for a limited period following which therapy resistance emerges– hence the challenge to develop alternate means for reducing intra-tumor androgen signaling. Design and Results: 3β-sulfation of dehydroepiandrosterone (DHEA), mediated by the prostate-expressed sulfotransferase SULT2B1b (hereon SULT), is likely to reduce intra-prostate androgen levels since sulfated DHEA cannot be converted to androstenedione and thus to testosterone and DHT. We tested whether enzyme-catalyzed sulfation of DHEA, the obligate precursor steroid for androgen synthesis, is targetable to inhibit prostate cancer. Results show that SULT silencing increased prostate cancer cell proliferation. Clinical prostate cancer specimens showed markedly reduced SULT expression, revealed by immunohistochemistry, western blotting and mRNA quantification. 1,25-dihydroxy vitamin D3 (D3) and sterols enhanced SULT expression due to induction of the SULT2B-encoding gene by D3-activated vitamin D receptor (VDR) and sterol-activated liver X receptor (LXRα). Conclusion: Tumor SULT levels may be a marker for predicting prostate cancer recurrence and progression. We also anticipate that enhancement of SULT activity in tumors by activating VDR and LXRα through combined therapeutic intervention with D3 and sterols would limit the tumor androgen pool and inhibit recurrent, therapy-resistant prostate cancer. Citation Format: Nooshin Mirkheshti, Chung S. Song, Bandana Chatterjee. Loss of steroid sulfotransferase (SULT) in human prostate cancer: Potential implications for SULT as a biomarker and therapeutic target. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1917. doi:10.1158/1538-7445.AM2013-1917

Novel Interaction between the Co-chaperone Cdc37 and Rho GTPase Exchange Factor Vav3 Promotes Androgen Receptor Activity and Prostate Cancer Growth*

Elevated androgen receptor (AR) activity in castration-resistant prostate cancer may occur through increased levels of AR co-activator proteins. Vav3, a guanine nucleotide exchange factor, is up-regulated following progression to castration resistance in preclinical models and is overexpressed in a significant number of human prostate cancers. Vav3 is a novel co-activator of the AR. We sought to identify Vav3 binding partners in an effort to understand the molecular mechanisms underlying Vav3 enhancement of AR activity and to identify new therapeutic targets. The cell division cycle 37 homolog (Cdc37), a protein kinase-specific co-chaperone for Hsp90, was identified as a Vav3 interacting protein by yeast two-hybrid screening. Vav3-Cdc37 interaction was confirmed by GST pulldown and, for native proteins, by co-immunoprecipitation experiments in prostate cancer cells. Cdc37 potentiated Vav3 co-activation of AR transcriptional activity and Vav3 enhancement of AR N-terminal-C-terminal interaction, which is essential for optimal receptor transcriptional activity. Cdc37 increased prostate cancer cell proliferation selectively in Vav3-expressing cells. Cdc37 did not affect Vav3 nucleotide exchange activity, Vav3 protein levels, or subcellular localization. Disruption of Vav3-Cdc37 interaction inhibited Vav3 enhancement of AR transcriptional activity and AR N-C interaction. Diminished Vav3-Cdc37 interaction also caused decreased prostate cancer cell proliferation selectively in Vav3-expressing cells. Taken together, we identified a novel Vav3 interacting protein that enhances Vav3 co-activation of AR and prostate cancer cell proliferation. Vav3-Cdc37 interaction may provide a new therapeutic target in prostate cancer.

Reactive oxygen species induced by p66Shc longevity protein mediate nongenomic androgen action via tyrosine phosphorylation signaling to enhance tumorigenicity of prostate cancer cells

Steroid hormones exhibit diverse biological activities. Despite intensive studies on steroid function at the genomic level, their nongenomic actions remain an enigma. In this study, we investigated the role of reactive oxygen species (ROS) in androgen-stimulated prostate cancer (PCa) cell proliferation. In androgen-treated PCa cells, increased cell growth and ROS production correlated with elevated p66Shc protein, an authentic oxidase. This growth stimulation was blocked by antioxidants. Further, elevated expression of p66Shc protein by cDNA transfection encoding wild-type protein, but not a redox-deficient (W134F) mutant, was associated with increased PCa cell proliferation. Conversely, knockdown of p66Shc expression by shRNA resulted in diminished cell growth. Increased p66Shc expression in PCa cells enhanced their tumorigenicity in xenograft animals. Importantly, p66Shc protein level is higher in clinical prostate adenocarcinomas than in adjacent noncancerous cells. Expression of redox-deficient p66Shc mutant protein abolished androgen-stimulated cell growth. In androgen-treated, H2O2-treated, and p66Shc cDNA-transfected PCa cells, cellular prostatic acid phosphatase, an authentic tyrosine phosphatase, was inactivated by reversible oxidation; subsequently, ErbB-2 was activated by phosphorylation at tyrosine-1221/1222. These results together support the notion that androgens induce ROS production through the elevation of p66Shc protein, which inactivates tyrosine phosphatase activity for the activation of interacting tyrosine kinase, leading to increased cell proliferation and enhanced tumorigenicity. Our results thus suggest that p66Shc protein functions at the critical junction point between androgens and tyrosine phosphorylation signaling in human PCa cells.

Abstract 3033: NKX2-5, a potential tumor suppressor gene in prostate cancer

Abstract Background: Prostate cancer (PCa) is a common malignancy and a leading cause of cancer deaths among men in the United States. Abundant evidence has accumulated to suggest that epigenetic DNA methylation changes may appear earlier during PCa development than genetic changes, as well as more commonly and consistently suggesting that DNA methylated genes can be explored as DNA-based biomarker for PCa disease detection. Recently, we have identified NKX2-5 as a novel that is hypermethylated in prostate cancer. However, there is little information about the biological significance of this gene in prostate carcinogenesis. We hypothesize that NKX2-5 is a potential tumor suppressor gene that is frequently inactivated in prostate cancer. Methods: We carried out gain-and-loss functional studies of NKX2-5 in prostate cancer cell lines and validated expression at the RNA transcript level using quantitative RT-PCR. Protein expression was analyzed by western blotting and cell cycle analysis investigated by flow cytometer. Results: Over-expression of NKX2-5 was detrimental to prostate cancer cell proliferation as evidenced by significant inhibition of prostate cancer cell proliferation in comparison to control (vector only transfection) and this was due to cell arrest in Go/G1 phase and increase apoptosis. In contract, successful knockdown of NKX2-5 by shRNA transfection increased prostate cancer cell proliferation. Western blot analysis demonstrated that NKX2-5 plays a key regulatory role in the expression of several genes including p53, PTEN, Histone H1 and the androgen receptor. Conclusion: Our observation suggests that NKX2-5, a member of the homeobox gene family of plays an important tumor suppressor activity in prostate carcinogenesis. Because this gene plays important role in several signal transduction pathways, this gene can be exploited as potential biomarker for the early detection of prostate cancer and could be an attractive target to explore for drug investigation or gene therapies of prostate cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3033. doi:10.1158/1538-7445.AM2011-3033

Hydrogen Peroxide Stimulates Proliferation and Migration of Human Prostate Cancer Cells through Activation of Activator Protein-1 and Up-regulation of the Heparin Affin Regulatory Peptide Gene

It is becoming increasingly recognized that hydrogen peroxide (HP) plays a role in cell proliferation and migration. In the present study we found that exogenous HP significantly induced human prostate cancer LNCaP cell proliferation and migration. Heparin affin regulatory peptide (HARP) seems to be involved in the stimulatory effect of HP, because the latter had no effect on stably transfected LNCaP cells that did not express HARP. Moreover, HP significantly increased HARP mRNA and protein amounts in a concentration- and time-dependent manner. Curcumin and activator protein-1 (AP-1) decoy oligonucleotides abrogated both HP-induced HARP expression and LNCaP cell proliferation and migration. HP increased luciferase activity of the 5'-flanking region of the HARP gene introduced in a reporter gene vector, an effect that was abolished when even one of the two putative AP-1 binding sites of the HARP promoter was mutated. The effect of HP seems to be due to the binding of Fra-1, JunD, and phospho-c-Jun to the HARP promoter. These results support the notion that HARP is important for human prostate cancer cell proliferation and migration, establish the role of AP-1 in the up-regulation of HARP expression by low concentrations of HP, and characterize the AP-1 dimers involved.