hMAGEA2 Accelerates the Progression of Prostate Cancer via the EFNA3-Erk1/2 Signaling Pathway.

BACKGROUND/AIM: Human melanoma-associated antigen A2 (hMAGEA2) family members play several roles in many types of cancer and have been explored as potential prognostic markers. In this study, we investigated the molecular mechanism underlying hMAGEA2-mediated tumorigenesis of prostate cancer. MATERIALS AND METHODS: Immunohistochemistry and western blot were used to assess protein expression whereas microarray and quantitative reverse transcription-PCR determined mRNA expression. CCK-8 assay was used to determine cell proliferation. Colony formation assay was used to examine tumorigenesis. Migration and invasion were examined using a transwell assay. Propidium iodide (PI)/Annexin V double staining was performed to measure apoptosis. Transcriptional activity was measured using Dual-luciferase reporter assay. RESULTS: hMAGEA2 was highly over-expressed in human prostate cancer tissues compared to benign prostatic hyperplasia tissues. To elucidate its biological function in prostate cancer, we established two stable hMAGEA2-knockdown prostate cancer cell lines, PC3M and 22RV1, and found that they presented significantly decreased proliferation, anchorage-independent colony formation, migration, and invasion. As hMAGEA2 knockdown suppressed prostate cancer cell growth, we examined its potential influence on tumor apoptosis. hMAGEA2-knockdown cell lines displayed early apoptosis. Moreover, knockdown of hMAGEA2 resulted in the down-regulation of EFNA3 expression. Luciferase assay showed that hMAGEA2 bound to the EFNA promoter region and regulated its transcription. Down-regulation of EFNA3 expression led to decreased Ras/Braf/MEK/Erk1/2 phosphorylation and, consequently, inhibited prostate cancer progression. CONCLUSION: hMAGEA2 promotes prostate cancer growth, metastasis, and tumorigenesis by regulating the EFNA3-Erk1/2 signaling pathway, indicating its potential as a therapeutic marker for prostate cancer.

ZNF507 affects TGF-ß signaling via TGFBR1 and MAP3K8 activation in the progression of prostate cancer to an aggressive state.

BACKGROUND: The progression of prostate cancer (PC) to the highly aggressive metastatic castration-resistant prostate cancer (mCRPC) or neuroendocrine prostate cancer (NEPC) is a fatal condition and the underlying molecular mechanisms are poorly understood. Here, we identified the novel transcriptional factor ZNF507 as a key mediator in the progression of PC to an aggressive state. METHODS: We analyzed ZNF507 expression in the data from various human PC database and high-grade PC patient samples. By establishment of ZNF507 knockdown and overexpression human PC cell lines, we assessed in vitro PC phenotype changes including cell proliferation, survival, migration and invasion. By performing microarray with ZNF507 knockdown PC cells, we profiled the gene clusters affected by ZNF507 knockdown. Moreover, ZNF507 regulated key signal was evaluated by dual-luciferase reporter and chromatin immunoprecipitation (ChIP) assays. Finally, we performed xenograft and in vivo metastasis assay to confirm the effect of ZNF507 knockdown in PC cells. RESULTS: We found that ZNF507 expression was increased, particularly in the highly graded PC. ZNF507 was also found to be associated with metastatic PC of a high grade. Loss- or gain-of-function-based analysis revealed that ZNF507 promotes the growth, survival, proliferation, and metastatic properties of PC (e.g., epithelial-mesenchymal transition) by upregulating TGF-ß signaling. Profiling of gene clusters affected by ZNF507 knockdown revealed that ZNF507 positively regulated the transcription of TGFBR1, MAP3K8, and FURIN, which in turn promoted the progression of PC to highly metastatic and aggressive state. CONCLUSIONS: Our findings suggest that ZNF507 is a novel key regulator of TGF-ß signaling in the progression of malignant PC and could be a promising target for studying the development of advanced metastatic PCs.

Inhibition of MAGEA2 regulates pluripotency, proliferation, apoptosis, and differentiation in mouse embryonic stem cells.

Mouse embryonic stem cells (mESCs) exhibit self-renewal and pluripotency, can differentiate into all three germ layers, and serve as an essential model in stem cell research and for potential clinical application in regenerative medicine. Melanoma-associated antigen A2 (MAGEA2) is not expressed in normal somatic cells but rather in different types of cancer, especially in undifferentiated cells, such as in the testis, differentiating cells, and ESCs. However, the role of MAGEA2 in mESCs remains to be clarified. Accordingly, in this study, we examined the expression and functions of MAGEA2 in mESCs. MAGEA2 messenger RNA (mRNA) expression was decreased during mESCs differentiation. MAGEA2 function was then evaluated in knockdown mESC. MAGEA2 knockdown resulted in decreased pluripotency marker gene expression in mESCs consequent to increased Erk1/2 phosphorylation. Decreased MAGEA2 expression inhibited mESC proliferation via S phase cell cycle arrest with a subsequent decrease in cell cycle-associated genes Cdk1, Cdk2, Cyclin A1, Cyclin D1, and Cdc25a. Apoptotic mESCs markedly increased along with cleaved forms of caspases 3, 6, and 7 and PARP expression, confirming caspase-dependent apoptosis. MAGEA2 knockdown significantly decreased embryoid body size in vitro when cells were differentiated naturally and teratoma size in vivo, concomitant with decreased ectoderm marker gene expression. These findings suggested that MAGEA2 regulates ESC pluripotency, proliferation, cell cycle, apoptosis, and differentiation. The enhanced understanding of the regulatory mechanisms underlying diverse mESC characteristics will facilitate the clinical application of mESCs.

Suppression of PRPF4 regulates pluripotency, proliferation, and differentiation in mouse embryonic stem cells.

Mouse embryonic stem cells (mESCs) are characterized by their self-renewal and pluripotency and are capable of differentiating into all three germ layers. For this reason, mESCs are considered a very important model for stem cell research and clinical applications in regenerative medicine. The pre-mRNA processing factor 4 (PRPF4) gene is known to have a major effect on pre-mRNA splicing and is also known to affect tissue differentiation during development. In this study, we investigated the effects of PRPF4 knockdown on mESCs. First, we allowed mESCs to differentiate naturally and observed a significant decrease in PRPF4 expression during the differentiation process. We then artificially induced the knockdown of PRPF4 in mESCs and observed the changes in the phenotype. When PRPF4 was knocked down, various genes involved in mESC pluripotency showed significantly decreased expression. In addition, mESC proliferation increased abnormally, accompanied by a significant increase in mESC colony size. The formation of mESC embryoid bodies and teratomas was delayed following PRPF4 knockdown. Based on these results, the reduced expression of PRPF4 affects mESC phenotypes and is a key factor in mESC. SIGNIFICANCE OF THE STUDY: Our results indicate that PRPF4 affects the properties of mESCs. Suppression of PRPF4 resulted in a decrease in pluripotency of mESC and promoted proliferation. In addition, suppression of PRPF4 also resulted in decreased apoptosis. Moreover, the inhibition of PRPF4 reduced the ability to differentiate and formation of teratoma in mESC. Our results demonstrated that PRPF4 is a key factor of controlling mESC abilities.

PRPF4 is a novel therapeutic target for the treatment of breast cancer by influencing growth, migration, invasion, and apoptosis of breast cancer cells via p38 MAPK signaling pathway.

Pre-mRNA processing factor 4 (PRPF4), a core protein in U4/U6 snRNP, maintains snRNP structures by interacting with PRPF3 and cyclophilin H. Expression of the PRPF4 gene affects cell survival as well as apoptosis and is responsible for retinitis pigmentosa (RP). Proteomics analysis shows that PRPF4 may be a therapeutic target in human cancers. Nevertheless, the exact function and role of the PRPF4 gene are unclear. In this study, we assessed the expression of PRPF4 gene in human breast cancer cells. First, we confirmed that the PRPF4 gene was overexpressed in various breast cancer cell lines. Next, using breast cancer cell lines MCF7 and MDA-MB-468, we established stable cell lines with PRPF4 gene knockdown. We also performed microarray analysis to investigate molecular mechanisms underlying PRPF4 activity. All cell lines with PRPF4 gene knockdown exhibited reduced cell proliferation, remarkable reduction in anchorage-independent colony formation capacity, and reduction of PCNA protein, which is a marker cell of proliferation. Reduced expression of the PRPF4 gene induced apoptosis and changes in the expression of associated apoptotic markers in breast cancer cell lines. Knockdown of the PRPF4 gene reduced cellular capacity for migration and invasion (the key hallmarks of human cancers) and decreased the expression of genes involved in epithelial-mesenchymal transition (EMT). Microarray results showed that the expression of PPIP5K1, PPIPK2, and YWHAE genes was reduced at the transcriptional level, leading to reduced phosphorylation of p38 MAPK. These findings suggest that knockdown of PRPF4 gene slows down breast cancer progression via suppression of p38 MAPK phosphorylation. In conclusion, the PRPF4 gene plays an important role in the growth of breast cancer cells and is therefore a potential therapeutic target.