SNORA70E promotes the occurrence and development of ovarian cancer through pseudouridylation modification of RAP1B and alternative splicing of PARPBP.

The present study demonstrated for the first time that SNORA70E, which belongs to box H/ACA small nucleolar noncoding RNAs (snoRNAs) who could bind and induce pseudouridylation of RNAs, was significantly elevated in ovarian cancer tissues and was an unfavourable prognostic factor of ovarian cancer. The over-expression of SNORA70E showed increased cell proliferation, invasion and migration in vitro and induced tumour growth in vivo. Further research found that SNORA70E regulates RAS-Related Protein 1B (RAP1B) mRNA through pseudouracil modification by combing with the pyrimidine synthase Dyskerin Pseudouridine Synthase 1 (DKC1) and increase RAP1B protein level. What's more, the silencing of DKC1/RAP1B in SNORA70E overexpression cells both inhibited cell proliferation, migration and invasion through reducing ß-catenin, PI3K, AKT1, mTOR, and MMP9 protein levels. Besides, RNA-Seq results revealed that SNORA70E regulates the alternative splicing of PARP-1 binding protein (PARPBP), leading to the 4th exon-skipping in PARPBP-88, forming a new transcript PARPBP-15, which promoted cell invasion, migration and proliferation. Finally, ASO-mediated silencing of SNORA70E could inhibit ovarian cancer cell proliferation, invasion, migration ability in vitro and inhibit tumorigenicity in vivo. In conclusion, SNORA70E promotes the occurrence and development of ovarian cancer through pseudouridylation modification of RAP1B and alternative splicing of PARPBP. Our results demonstrated that SNORA70E may be a new diagnostic and therapeutic target for ovarian cancer.

CircRNA WHSC1 targets the miR-646/NPM1 pathway to promote the development of endometrial cancer.

Circular RNAs (circRNAs) play important roles in human cancer progression. Their high stability and tissue specificity make circRNAs important molecular targets for clinical diagnosis, treatment and prognosis. However, the functions and molecular mechanisms of circRNA WHSC1 in endometrial cancer are unknown. CircWHSC1 expression in normal endometrial and endometrial cancer tissues was detected using PCR. Overexpression or knockdown of circWHSC1 in endometrial cancer cell lines HEC-1B or Ishikawa, respectively, cell function experiments were used to detect the impact of circWHSC1 on endometrial cancer cells. A nude mouse xenograft model was used to detect changes in tumorigenesis of HEC-1B cells after circWHSC1 overexpression. Bioinformatics and dual luciferase reporter gene technology were used to predict and validate the sponging ability of circWHSC1 on microRNAs. Gene expression changes were detected by using Western blotting. CircWHSC1 expression was increased in endometrial cancer tissues. CircWHSC1 overexpression promoted the proliferation, migration and invasion of endometrial cancer cells and decreased apoptosis. CircWHSC1 knockdown had the opposite effect. CircWHSC1 overexpressed nude mice showed increased tumorigenicity. Bioinformatics predicted that circWHSC1 binds to miR-646, which was confirmed using luciferase reporter gene assays. High expression of miR-646 could reverse the effect of circWHSC1 on endometrial cancer cells. Western blotting showed increased or decreased levels of nucleophosmin 1 (NPM1), an miR-646 downstream target, after circWHSC1 overexpression or knockdown, respectively. CircWHSC1 promotes endometrial cancer development through sponging miR-646 and targeting NPM1.

Circ_PUM1 promotes the development of endometrial cancer by targeting the miR-136/NOTCH3 pathway.

Endometrial cancer is one of the most common gynaecological malignancies and the sixth most common cause of cancer-related death among women. Here, we define the role and molecular mechanism of circ_0000043 (hereafter referred to as circ_PUM1) in the development and progression of endometrial carcinoma. QRT-PCR was used to detect the expression of circ_PUM1 in normal endometrial tissue and endometrial carcinoma tissues. Changes in cell function and tumorigenicity in nude mice were examined after circ_PUM1 overexpression or knockdown. Bioinformatic analysis and dual-luciferase reporter assay were used to predict and analyse the miRNAs that circ_PUM1 binds. Gene expression changes were analysed using Western blot. Circ_PUM1 was expressed at significantly higher levels in endometrial cancer tissues than in normal tissues. Up-regulation of circ_PUM1 promoted the proliferation, migration and invasion of endometrial carcinoma cells. Opposite results were observed with circ_PUM1 knockdown, and the tumorigenic ability of endometrial cancer cells after circ_PUM1 knockdown was reduced compared to control cells. Circ_PUM1 is capable of binding to miR-136, and up-regulating its target gene NOTCH3, which can be reversed by overexpression of miR-136. Circ_PUM1 can compete with miR-136, leading to up-regulation of NOTCH3, and thereby promote the development of endometrial cancer.

CircRhoC promotes tumorigenicity and progression in ovarian cancer by functioning as a miR-302e sponge to positively regulate VEGFA.

Ovarian cancer is a leading cause of deaths due to gynaecological malignancy. While endogenous non-coding circular RNAs (circRNAs) in cancer have attracted attention, their roles in ovarian cancer are not known. We used qRT-PCR to quantify expression of circRhoC in ovarian cancer tissues and normal tissues. The effects of overexpressing or destruction of circRhoC on the phenotype of ovarian cancer cells were assessed both in vitro and in vivo. Dual-luciferase reporter assay assesses the microRNA sponge function of circRhoC. Western blotting was used to confirm the effects of circRhoC and microRNA on target gene expression. Our results showed that circRhoC was significantly up-regulated in ovarian cancer tissues compared to normal ovarian tissues. Overexpression of circRhoC in CAOV3 ovarian cancer cell increased cell viability, migration and invasion ability; destroying circRhoC in A2780 had the opposite effects and inhibited ovarian tumour cell A2780 dissemination in the peritoneum in vivo. We confirmed circRhoC functions as a sponge for miR-302e to positively regulate VEGFA; FISH experiments showed that circRhoC could co-focal with miR-302e; besides, overexpression of miR-302e reversed the ability of circRhoC to positively regulate VEGFA, and what's more, RIP assay showed that circRhoC could directly bind with VEGFA; besides, VEGFA expression level in ovarian cancer tissues was positively associated with circRhoC expression. In conclusion, the oncogenic effect of RhoC in ovarian cancer is at least in part due to circRhoC, which functions not only as a miR-302e sponge to positively regulate VEGFA protein expression, but may also directly bind and modulate VEGFA expression.

BAG3 promotes proliferation of ovarian cancer cells via post-transcriptional regulation of Skp2 expression.

Bcl-2 associated athanogene 3 (BAG3) contains a modular structure, through which BAG3 interacts with a wide range of proteins, thereby affording its capacity to regulate multifaceted biological processes. BAG3 is often highly expressed and functions as a pro-survival factor in many cancers. However, the oncogenic potential of BAG3 remains not fully understood. The cell cycle regulator, S-phase kinase associated protein 2 (Skp2) is increased in various cancers and plays an important role in tumorigenesis. The current study demonstrated that BAG3 promoted proliferation of ovarian cancer cells via upregulation of Skp2. BAG3 stabilized Skp2 mRNA via its 3'-untranslated region (UTR). The current study demonstrated that BAG3 interacted with Skp2 mRNA. In addition, miR-21-5p suppressed Skp2 expression, which was compromised by forced BAG3 expression. These results indicated that at least some oncogenic functions of BAG3 were mediated through posttranscriptional regulation of Skp2 via antagonizing suppressive action of miR-21-5p in ovarian cancer cells.

LncRNA ABHD11-AS1 promotes the development of endometrial carcinoma by targeting cyclin D1.

To investigate the expression, role and mechanism of action of long non-coding RNA (lncRNA) ABHD11-AS1 in endometrial carcinoma. The expression of lncRNA ABHD11-AS1 was quantified by qRT-PCR in human endometrial carcinoma (n = 89) and normal endometrial tissues (n = 27). LncRNA ABHD11-AS1 was stably overexpressed or knocked-down in endometrial carcinoma cell lines to examine the cellular phenotype and expression of related molecules. Compared to normal endometrial tissue, lncRNA ABHD11-AS1 was significantly overexpressed in endometrial carcinoma. Overexpression of lncRNA ABHD11-AS1 promoted the proliferation, G1-S progression, invasion and migration of endometrial cancer cells; inhibited apoptosis; up-regulated cyclin D1, CDK1, CDK2, CDK4, Bcl-xl and VEGFA; and down-regulated p16, while ABHD11-AS1 down-regulation has the opposite effect. RNA pull down demonstrated that lncRNA ABHD11-AS1 binds directly to cyclin D1. Knockdown of cyclin D1 can reverse the effect of ABHD11-AS1. Overexpression of lncRNA ABHD11-AS1 increased the tumorigenicity and up-regulated cyclin D1 in an in vivo model of endometrial cancer in nude mice. LncRNA ABHD11-AS1 functions as an oncogene to promote cell proliferation and invasion in endometrial carcinoma by positively targeting cyclin D1.

LncRNA PCGEM1 Induces Ovarian Carcinoma Tumorigenesis and Progression Through RhoA Pathway.

BACKGROUND/AIMS: Prostate cancer gene expression marker 1 (PCGEM1) is a long noncoding RNA (lncRNA) and is well known as a promoter in prostate cancer and osteoarthritis synoviocytes. However, the role PCGEM1 plays in epithelial ovarian cancer is unknown. METHODS: PCGEM1 expression was examined in epithelial ovarian cancer and normal ovarian tissues using reverse transcription-PCR. Ovarian cancer cell phenotypes and genotypes were examined after PCGEM1 overexpression or downregulation in vitro; besides, the effects of PCGEM1 overexpression was also examined in vivo. RESULTS: PCGEM1 expression level was higher in epithelial ovarian cancer tissues than in normal ovarian tissues and was positively associated with differentiation (Well vs. Mod/Poor). Upregulation of PCGEM1 induced cancer cell proliferation, migration, and invasion, but decreased cell apoptosis through upregulating RhoA, YAP (Yes-associated protein), MMP2 (matrix metalloproteinase 2), Bcl-xL, and P70S6K expression; while PCGEM1 downregulation had the opposite effect. The nude mouse xenograft assay demonstrated that PCGEM1 overexpression promoted tumor growth. Furthermore, silencing RhoA expression reversed the effect of PCGEM1 and significantly inhibited RhoA, YAP, MMP2, Bcl-xL, and P70S6K protein expression. CONCLUSION: In conclusion, we suggest that PCGEM1 may be an inducer in epithelial ovarian cancer tumorigenesis and progression by upregulating RhoA and the subsequent expression of YAP, P70S6K, MMP2, and Bcl-xL.

PUM1 promotes ovarian cancer proliferation, migration and invasion.

BACKGROUND: Abnormal expression of the PUM1 gene (pumilio RNA binding family member 1) is closely related to chromosomal mutations and carcinogenesis. However, there is no report about expression or function of PUM1 in ovarian cancer. The present study explored the role of PUM1 in the development and progression of ovarian cancer. METHODS: Immunohistochemistry was used to detect the expression of PUM1 in normal ovarian tissues and ovarian cancer tissues. The PUM1 gene was silenced using small interfering RNAs in ovarian cancer cell line A2780. MTT, plate colony formation and EdU (5-ethynyl-2'-deoxyuridine) assays were used to detect cell growth, and cell apoptosis was detected by flow cytometry. Wound-healing and Transwell assays were performed to determine cell migration and invasion. Western blotting was used to detect the levels of cancer-related proteins. RESULTS: Immunohistochemistry showed that the level of PUM1 in ovarian cancer tissues was higher than that in normal tissues. The cell proliferation, migration, and invasion ability decreased significantly, while cell apoptosis increased after silencing the PUM1 gene. Moreover, western blotting showed that downregulation of PUM1 decreased the levels of STAT3, BCL2, MMP2, and VEGFA. CONCLUSIONS: Thus, PUM1 promotes the development and progression of ovarian cancer, which may occur via the above-mentioned molecules.

LncRNA TDRG1 enhances tumorigenicity in endometrial carcinoma by binding and targeting VEGF-A protein.

Endometrial carcinoma is one of the most frequently diagnosed cancers in females. Long non-coding RNAs (lncRNAs) have been associated with cancer; its role in endometrial carcinoma is an emerging area of research. In this article, lncRNA TDRG1 expression in human endometrial carcinoma tissues and normal endometrial tissues was quantified by qRT-PCR. LncRNA TDRG1 was overexpressed or knocked-down in neither HEC-1B nor Ishikawa endometrial carcinoma cells, respectively, to assess cellular phenotype and expression of related molecules. Our results showed that lncRNA TDRG1 was significantly overexpressed in endometrial carcinoma tissues. Overexpression of lncRNA TDRG1 promoted endometrial carcinoma cell viability, invasion and migratory ability, inhibited apoptosis, and upregulated VEGF-A, PI3K, Bcl-2, MMP2 and survivin; knockdown of lncRNA TDRG1 had the opposite effects. LncRNA TDRG1 overexpression increased tumorigenicity in vivo and was associated with the upregulation of VEGF-A. RNA binding protein immunoprecipitation (RIP) assays confirmed that lncRNA TDRG1 directly binds to VEGF-A protein. Furthermore, knockdown of VEGFA in lncRNA TDRG1-overexpressing endometrial carcinoma cells reversed the effects of lncRNA TDRG1 on cell proliferation, invasion, migration and apoptosis. In conclusion, lncRNA TDRG1 may promote endometrial carcinoma cell proliferation and invasion by positively targeting VEGF-A and modulating relative genes.

The role of the long non-coding RNA TDRG1 in epithelial ovarian carcinoma tumorigenesis and progression through miR-93/RhoC pathway.

As one of the most frequently diagnosed cancers in women, the development and progression of epithelial ovarian carcinoma (EOC) remains an open area of research. The role of long non-coding RNAs (lncRNAs) in EOC is an emerging field of study. We found that LncRNA TDRG1 (human testis development-related gene 1) was highly expressed in EOC tissues than in normal ovarian tissues, and expression differed significantly with differentiation. LncRNA TDRG1 downregulation suppressed EOC cell proliferation, migration, and invasion, while its overexpression had the opposite effect. Bioinformatic predictions and dual-luciferase reporter assays showed that LncRNA TDRG1 has possible miRNA-93 (miR-93) binding sites. LncRNA TDRG1 downregulation upregulated miR-93 expression, while its overexpression reduced miR-93 expression. In addition, TDRG1 downregulation reduced the expression of Ras homolog gene family member C (RhoC), P70 ribosomal S6 kinase (P70S6 K), Bcl-xL, and matrix metalloproteinase 2 (MMP2) protein, which are regulated by miR-93, while its upregulation induced RhoC, P70S6 K, Bcl-xL, and MMP2 protein expression. In vivo, LncRNA TDRG1 overexpression induced tumor development and RhoC expression. Taken together, our results demonstrated for the first time that LncRNA TDRG1 may be a new and important diagnostic and therapeutic target in EOC.

DLEU1 contributes to ovarian carcinoma tumourigenesis and development by interacting with miR-490-3p and altering CDK1 expression.

Recently, a large number of studies have focused on the important role of long non-coding RNAs (lncRNAs) in metabolism and development and have found that abnormal lncRNA expression is associated with the pathogenesis and development of many diseases. The lncRNA DLEU1 is involved in many solid tumours and haematological malignancies. However, its role in epithelial ovarian carcinoma (EOC) and the associated molecular mechanisms has not been reported. In this study, quantitative reverse transcription-PCR (qRT-PCR) demonstrated higher lncRNADLEU1 expression in EOC tissues than in normal tissues. Plasmid transfection of DLEU1 to up-regulate its expression in the ovarian cancer cell lines A2780 and OVCAR3 increased cell proliferation, migration, and invasion, while inhibited apoptosis. Nude mouse xenograft assay demonstrated that DLEU1 overexpression promoted tumour growth in vivo. QRT-PCR showed decreased miR-490-3p expression, while Western blotting demonstrated increased its target genes CDK1, cyclinD1 and SMARCD1, as well as matrix metalloproteinase-2 (MMP2), Bcl-xL and P70S6K protein expression, respectively. Short interfering RNA silencing of DLEU1 produced opposite results, where qRT-PCR showed increased miR-490-3p expression. The dual-luciferase reporter assay revealed a direct interaction between DLEU1 and miR-490-3p. MiR-490-3p plays a tumour suppressor role in epithelial ovarian cancer by targeting CDK1 regulation and influencing SMARCD1 and cyclin D1 (CCND1) expressions. Therefore, we suggest that through interaction with miR-490-3p, DLEU1 may influence the expression of CDK1, CCND1 and SMARCD1 protein, subsequently promoting the development and progression of EOC.

LncRNA MEG3 inhibit endometrial carcinoma tumorigenesis and progression through PI3K pathway.

Long noncoding RNAs (lncRNAs) are RNA molecules more than 200 nucleotides in length that do not encode proteins. Recent studies have reported increasing numbers of functional lncRNAs. Maternally expressed gene 3 (MEG3) is a maternally imprinted gene encoding an lncRNA that plays a tumor suppressor role in various tumors. However, there has been rare report on mechanism of tumorigenesis and progression of endometrial carcinoma. In the present study, we found significantly lower MEG3 expression in endometrial carcinoma tissues than in normal endometrial tissues. MEG3 overexpression inhibited endometrial cancer cell proliferation, invasion, and metastasis; promoted apoptosis; and inhibited the activation of the phosphoinositide 3-kinase (PI3K)/m-TOR signaling pathway. RNA immunoprecipitation assay (RIP) showed that MEG3 can combine directly with PI3K. Tumor xenograft implantation in nude mice showed that MEG3 could significantly suppress tumor growth. These findings provide potential new therapeutic targets for treating endometrial cancer.

The role of metastasis-associated in colon cancer 1 (MACC1) in endometrial carcinoma tumorigenesis and progression.

Metastasis-associated in colon cancer-1 (MACC1), has recently been identified as a key regulator in the progression of many cancers. However, its role in endometrial carcinoma (EC) remains unknown. MACC1 expression was determined in EC and normal endometrial tissues by immunohistochemistry. EC cell phenotypes and related molecules were examined after MACC1 downregulation by Small interfering RNA (siRNA) or microRNA (miRNA) transfection. We found that MACC1 was highly expressed in EC tissues than normal samples, and was significantly different in FIGO staging (I and II vs. III and IV), the depth of myometrial infiltration (<1/2 vs. ≥1/2), lymph nodes metastasis (negative vs. positive), besides, MACC1 overexpression was correlated with lower cumulative and relapse-free survival rate. MACC1 downregulation by siRNA transfection significantly induced G1 phrase arrest, suppressed EC cell proliferation, migration, and invasion. In addition, MACC1 downregulation also reduced expression of Cyclin D1 and Cyclin-dependent Kinase 2 (CDK2), N-cadherin (N-Ca), α-SMA, matrix metalloproteinase 2 (MMP2), and MMP9, but increased expression of E-cadherin (E-Ca). Bioinformatic predictions and dual-luciferase reporter assays indicate that MACC1 is a possible target of miR-23b. MiR-23b overexpression reduced MACC1 expression in vitro and induced G1 phrase arrest, suppressed cell proliferation, migration, and invasion. MiR-23b transfection also reduced Cyclin D1 and CDK2, N-Ca, α-SMA, MMP2, MMP9 expression, but increased E-Ca expression. Furthermore, the nude mouse xenograft assay showed that miR-23b overexpression suppressed tumour growth through downregulating MACC1 expression. Taken together, our results demonstrate for the first time that MACC1 may be a new and important diagnosis and therapeutic target of endometrial carcinoma.

MicroRNA-505 functions as a tumor suppressor in endometrial cancer by targeting TGF-α.

BACKGROUND: Endometrial carcinoma (EC) is one of the most lethal gynecologic cancers. Patients frequently have regional or distant metastasis at diagnosis. MicroRNAs are small non-coding RNAs that participate in numerous biological processes. Recent studies have demonstrated that miR-505 is associated with several types of cancer; however, the expression and function of miR-505 have not been investigated in EC. METHODS: miR-505 expression in normal endometrial tissue, endometrial carcinomas were quantified by Quantitative reverse transcription PCR. The endometrial carcinoma cell lines HEC-1B and Ishikawa were each transfected with miR-505 or scrambled mimics, after which cell phenotype and expression of relevant molecules were assayed. Dual-luciferase reporter assay and a xenograft mouse model were used to examine miR-505 and its target gene TGF-α. RESULTS: RT-PCR results demonstrated that miR-505 was significantly downregulated in human EC tissues compared to normal endometrial tissues. Besides, miR-505 expression was negatively associated with FIGO stage (stage I-II vs. III-IV), and lymph node metastasis (negative vs. positive). In vitro, overexpression of miR-505 significantly suppressed EC cell proliferation, increased apoptosis and reduced migratory and invasive activity. A miR-505 binding site was identified in the 3' untranslated region of TGF-α mRNA (TGFA) using miRNA target-detecting software; a dual luciferase reporter assay confirmed that miR-505 directly targets and regulates TGFA. RT-PCR and Western-blotting results indicated that overexpressing miR-505 reduced the expression of TGF-α and the TGF-α-regulated proteins MMP2, MMP9, CDK2, while induced Bax and cleaved-PARP expression in EC cells. In vivo, overexpression of miR-505 reduced the tumorigenicity and inhibited the growth of xenograft tumors in a mouse model of EC. CONCLUSIONS: Taken together, this study demonstrates that miR-505 acts as tumor suppressor in EC by regulating TGF-α.

MicroRNA-873 mediates multidrug resistance in ovarian cancer cells by targeting ABCB1.

Ovarian cancer is commonly treated with cisplatin and paclitaxel combination chemotherapy; however, ovarian cancer cells often develop resistance to these drugs. Increasingly, microRNAs (miRNAs) including miR-873 have been implicated in drug resistance in many cancers, but the role of miR-873 in ovarian cancer remains unknown. MTT cell viability assays revealed that the sensitivities of ovarian cancer lines to cisplatin and paclitaxel increased following transfection with miR-873 (P < 0.05). After predicting the miR-873 binding region in the 3'-untranslated region of ABCB1, dual-luciferase reporter assay confirmed this prediction. RT-PCR and Western blotting revealed that MDR1 expression was significantly downregulated after transfection with miR-873 and upregulated after transfection with anti-miR-873 at both mRNA and protein levels compared to negative controls (P < 0.05). Experiments in a mouse xenograft model confirmed that intratumoral administration of miR-873 could enhance the efficacy of cisplatin in inhibiting tumor growth in ovarian cancer in vivo (P < 0.05). ABCB1 overexpression reduced sensitivities of ovarian cancer lines OVCAR3 and A2780 to cisplatin and paclitaxel, which can be reversed by miR-873 mimic transfection (P < 0.05). In summary, we demonstrated that overexpression of miR-873 increased the sensitivity of ovarian cancer cells to cisplatin and paclitaxel by targeting MDR1 expression. Our findings suggest that combination therapies with chemotherapy agents and miR-873 may suppress drug resistance in ovarian cancer.

RhoC is a major target of microRNA-93-5P in epithelial ovarian carcinoma tumorigenesis and progression.

BACKGROUND: An increasing amount of evidence has revealed that microRNAs regulate various biological processes, including cell differentiation, cell proliferation, apoptosis, drug resistance, and fat metabolism. Studies have shown that miR-93's targetome in cancer has not been fully defined. Moreover, the role of miR-93 in epithelial ovarian carcinoma (EOC) remains largely unknown. METHODS: MIR-93 mRNA expression in normal ovarian tissue, benign tumors, borderline tumors, primary ovarian carcinomas, and metastatic omentum was quantified. The ovarian carcinoma cell lines OVCAR3, SKOV3/DDP, and HO8910-PM were transfected with miR-93-5P, after which cell phenotype and expression of relevant molecules were assayed. Dual-luciferase reporter assay and a xenograft mouse model were used to examine miR-93 and its target gene RHOC (Ras homolog gene family member C). RESULTS: MIR-93 mRNA expression was significantly lower in ovarian carcinomas and borderline tumors than in normal ovarian tissues (p < 0.05), and was lower in metastatic omentum than in relative primary ovarian carcinomas (p < 0.05). MIR-93 mRNA expression was also negatively associated with differentiation (well vs. poor and moderate) and International Federation of Gynecology and Obstetrics staging (FIGO stage I/II vs. stage III/IV) in ovarian carcinoma (p < 0.05), besides, miR-93 was higher expressed in mucinous adenocarcinoma than the other types (p < 0.05). MiR-93-5P overexpression reduced proliferation (p < 0.05); promoted G1 or S arrest and apoptosis (p < 0.05); suppressed migration and invasion (p < 0.05); and reduced RhoC, P70S6 kinase, Bcl-xL, matrix metalloproteinase 9 (MMP9) mRNA or protein expression; conversely, it induced P53 and cleaved PARP expression (p < 0.05). Dual-luciferase reporter assay indicated that miR-93 directly targeted RhoC by binding its 3' untranslated region. MiR-93-5P transfection also suppressed tumor development and RhoC expression (determined by immunohistochemistry) in vivo in the xenograft mouse model (p < 0.05). CONCLUSIONS: This is the first demonstration that miR-93-5P may inhibit EOC tumorigenesis and progression by targeting RhoC. These findings indicate that miR-93-5P is a potential suppressor of ovarian cellular proliferation. The involvement of miR-93-5P-mediated RhoC downregulation in inhibiting EOC aggressiveness may provide extended insight into the molecular mechanisms underlying cancer aggressiveness.

BAG3 is upregulated by c-Jun and stabilizes JunD.

BAG3 plays a regulatory role in a number of cellular processes, including cell proliferation, apoptosis, adhesion and migration, epithelial-mesenchymal transition (EMT), autophagy activation, and virus infection. The AP-1 transcription factors are implicated in a variety of important biological processes including cell differentiation, proliferation, apoptosis and oncogenesis. Recently, it has been reported that AP-1 protein c-Jun inhibits autophagy and enhances apoptotic cell death mediated by starvation. However, the molecular mechanisms remain unclear. For the first time, the current study demonstrated that serum starvation downregulated BAG3 at the transcriptional level via c-Jun. In addition, the current study reported that BAG3 stabilized JunD mRNA, which was, at least in part, responsible for the promotion of serum starvation mediated-growth inhibition by BAG3.

BAG3 sensitizes cancer cells exposed to DNA damaging agents via direct interaction with GRP78.

Bcl-2 associated athanogene 3 (BAG3) has a modular structure that contains a BAG domain, a WW domain, a proline-rich (PxxP) domain to mediate potential interactions with chaperons and other proteins that participate in more than one signal transduction. In search for novel interacting partners, the current study identified that 78kDa glucose-regulated protein (GRP78) was a novel partner interacting with BAG3. Interaction between GRP78 and BAG3 was confirmed by coimmunoprecipitation and glutathione S-transferase (GST) pulldown. We also identified that the ATPase domain of GRP78 and BAG domain of BAG3 mediated their interaction. Counterintuitive for a prosurvival protein, BAG3 was found to promote the cytotoxicity of breast cancer MCF7, thyroid cancer FRO and glioma U87 cells subjected to genotoxic stress. In addition, the current study demonstrated that BAG3 interfered with the formation of the antiapoptotic GRP78-procaspase-7 complex, which resulted in an increased genotoxic stress-induced cytotoxicity in cancer cells. Furthermore, overexpression of GRP78 significantly blocked the enhancing effects of BAG3 on activation of caspase-7 and induction of apoptosis by genotoxic stress. Overall, these results suggested that through direct interaction BAG3 could prevent the antiapoptotic effect of GRP78 upon genotoxic stress.

Implication of Nrf2 and ATF4 in differential induction of CHOP by proteasome inhibition in thyroid cancer cells.

Proteasome inhibition may cause endoplasmic reticulum (ER) stress, which has been reported to be implicated in the antitumoral effects of proteasome inhibitors. CCAAT/enhancer-binding protein homologous protein (CHOP) is induced by a variety of adverse physiological conditions including ER stress and is involved in apoptosis. We have reported that distinct induction of CHOP contributes to the responsiveness of thyroid cancer cells to proteasome inhibitors. However, the mechanism underlying differential induction of CHOP by proteasome inhibitors in thyroid cancer cells has not been well characterized. In the current study, we characterized that proteasome inhibition primarily activated the amino acid response element 1 (AARE1) on the CHOP promoter. We also demonstrated that although proteasome inhibition caused similar accumulation of activating transcription factor 4 (ATF4) in a panel of thyroid cancer cells, distinct amounts of ATF4 were recruited to the AARE1 element of CHOP promoter. In addition, we demonstrated that NF-E2-related factor 2 (Nrf2) was also implicated in the induction of CHOP by precluding the binding of ATF4 to the CHOP promoter. This study highlights the molecular mechanisms by which ATF4 and Nrf2 can control CHOP induction in thyroid cancer cells by proteasome inhibition.

Implication of 14-3-3ε and 14-3-3θ/τ in proteasome inhibition-induced apoptosis of glioma cells.

Proteasome inhibitors represent a novel class of anticancer agents that are used in the treatment of hematologic malignancies and various solid tumors. However, mechanisms underlying their anticancer actions were not fully understood. It has been reported that strong 14-3-3 protein expression is observed and associated with tumor genesis and progression of astrocytoma. In addition, global inhibition of 14-3-3 functions with a general 14-3-3 antagonist difopein induces apoptosis of human astrocytoma cells, validating 14-3-3 as a potential molecular target for anticancer therapeutic management. In the current study, for the first time we demonstrated that proteasome inhibitors downregulated 14-3-3ε and 14-3-3θ/τ in U87 and SF295 glioma cells. Overexpression of 14-3-3ε and 14-3-3θ/τ significantly suppressed apoptosis of human glioma cells induced by proteasome inhibitors. We also demonstrated that MG132 activated ASK1 and siASK1 compromised the MG132-induced apoptosis of glioma cells. Furthermore, overexpression of 14-3-3ε and 14-3-3θ/τ markedly suppressed activation of ASK1. Collectively, the current study supported that proteasome inhibitors, at least in part, caused cytotoxicity of glioma cells via downregulation of 14-3-3ε and 14-3-3θ/τ and subsequent activation of ASK1.