The short inverted repeats-induced circEXOC6B inhibits prostate cancer metastasis by enhancing the binding of RBMS1 and HuR.

Circular RNAs (circRNAs) are a novel class of endogenous RNAs with a covalently closed loop structure. Many circRNAs have been found to participate in cancer progression. However, the detailed generation process, functions, and related mechanisms of circRNAs in prostate cancer (PCa) remain largely unknown. In the present study, we identified circEXOC6B, a novel suppressor in the metastasis of PCa. Functionally, circEXOC6B, originating from the exocyst complex component 6B (EXOC6B) gene, inhibited migration and invasion of PCa in vitro and in vivo. Mechanistically, by acting as a protein scaffold, circEXOC6B enhanced the binding of human RNA binding motif single strand interacting protein 1 (RBMS1) and human antigen R (HuR) and further increased A-kinase anchoring protein 12 (AKAP12) expression to inhibit PCa metastasis. Unlike previous studies, we found that one pair of short inverted repeats in flanking introns at least partly promoted the circularization of circEXOC6B. Our study presents a novel mechanism for the inhibitory role of circEXOC6B in PCa metastasis and provides new insight into the molecular process of circRNA generation.

[Activation of p21(WAF1/CIP1) by small activating RNA inhibits cell proliferation and induces apoptosis in BEL-7402 hepatoma cell].

OBJECTIVE: To evaluate the anti neoplastic effects of p21(WAF1/CIP1) transcriptional activation induced by duplex RNAs in hepatocellular carcinoma (HCC) cell line BEL-7402. METHODS: Cells were treated with dsRNAs complementary to promoter sequences of p21(WAF1/CIP1). Quantitative polymerase chain reaction (qPCR) and Western blot were employed to detect the expression of p21. At various timepoints post-transfection, cell viability assay and apoptosis analysis were used to determine the effect of RNA activation. After transfection Western blot was also performed to detect the expression of Bcl-xL, cleaved caspase-3, cleaved caspase-9 and cleaved PARP. RESULTS: DsP21-322 transfection significantly inhibited cell viability. And, at Day 5, dsP21-322 inhibited cell growth by 65.84% versus control. Flow cytometry revealed that dsP21-322 caused a significant increase of cell apoptosis. The total percent of apoptotic cells (UR+LR) increased to 36.86% versus 11.51% and 14.06% in mocks and controls respectively. Such phenomena correlated with a decrease of anti-apoptotic protein Bcl-xL and an increase of cleaved caspase-3, cleaved caspase-9 and cleaved PARP. CONCLUSION: Activation of p21 gene expression by saRNA may offer therapeutic benefits for HCC and other cancers.

Urine- and Blood-Based Molecular Profiling of Human Prostate Cancer.

Objective: Prostate cancer (PCa) is one of the most common malignant tumors, accounting for 20% of total tumors ranked first in males. PCa is usually asymptomatic at the early stage and the specificity of the current biomarkers for the detection of PCa is low. The present study evaluates circulating tumor DNA (ctDNA) in blood or urine, which can be used as biomarkers of PCa and the combination of these markers may increase the sensitivity and specificity of the detection of PCa. Methods: Tissue, blood, and urine samples were collected from patients with PCa. All prostate tissue specimens underwent pathological examination. A hybrid-capture-based next-generation sequencing assay was used for plasma and urinary ctDNA profiling. Sequencing data were analyzed by an in-house pipeline for mutation calling. Mutational profiles of PCa and BPH were compared in both plasma and urine samples. Associations of detected mutations and clinical characteristics were statistically analyzed. Results: A significant association of mutation allele frequencies (MAFs) in the blood samples with patients with metastatic PCa rather than patients with primary PCa, and MAFs are changed after treatment in patients with PCa. Further, the number of mutations in urine is not associated with clinical characteristics of PCa patients, but the frequencies of mutation alleles in the urine are associated with patient age. Comparison of cfDNA aberration profiles between urine and blood reveals more alterations in urine than in blood, including TP53, AR, ATM, MYC, and SPOP mutations. Conclusion: This work provides the potential clinical application of urine, in addition to blood, as a powerful and convenient non-invasive approach in personalized medicine for patients with PCa.

Clinicopathological signature of p21-activated kinase 1 in prostate cancer and its regulation of proliferation and autophagy via the mTOR signaling pathway.

Prostate cancer (PCa) is one of the most common malignant tumors in men. The etiology and pathogenesis of PCa remain unclear. P21-activated kinase 1 (PAK1) is a member of a family of serine/threonine kinases and regulates cell growth and contributes to tumor invasion and metastasis. However, the association of PAK1 with PCa tumorigenesis and in particular with cell autophagy remains unknown. We found that the positive expression of PAK1 was significantly increased in PCa patients compared with BPH patients (P < 0.05). The expression of PAK1, p-PAK1 and LC3B1 in DU145 was increased by the activator of mTOR MYH1485. The expression of PAK1, p-PAK1, mTOR and Beclin1 decreased in PAK1-shRNA expressing DU145 cell. Knocking down of PAK1 inhibited DU145 cell growth, invasion and migration in vitro, and inhibited tumor growth in vivo. Our study demonstrated that PAK1 is upregulated in PCa and regulated by the mTOR signaling pathway and contributes to tumor autophagy. Thus, PAK1 may be a potential tumor marker and therapeutic target of PCa.

Transcriptional regulation of E-cadherin by small activating RNA: A new double-stranded RNA.

Recent studies have reported that chemically synthesized small activating RNA (saRNA) targeting the promoter regions of a gene can activate its expression in different cell lines. This technique can be a powerful therapeutic method for diseases caused by complete inactivation or reduced expression of specific genes. E-cadherin is a typical tumor suppressor gene. Loss of E-cadherin mediates the transition from benign lesions to invasive, metastatic cancer. In this study, several 21-nt small double-stranded RNAs (dsRNAs) targeting the promoter regions of human E-cadherin were designed and synthesized and the features of their function were investigated to study the regulatory role of dsRNA on E-cadherin expression. A new saRNA (dsEcad­661) that can enhance E-cadherin expression by targeting non-coding regulatory regions in gene promoters was identified. Using dsRNA with modified base quantity and cholesterol-conjugated dsRNA, we found the antisense strand may be the guide strand of saRNA in the upregulation of E-cadherin. These findings provide several important pieces of evidence that may improve understanding of the function of saRNA and may promote its development for clinical application.

The histone demethylase PHF8 promotes prostate cancer cell growth by activating the oncomiR miR-125b.

AIMS: Prostate cancer (PCa) is the most frequently diagnosed malignancy in men. However, the underlying mechanism is not fully understood. In this study, we aim to research the molecular mechanisms underlying the initiation and progression of PCa. RESULTS: Plant homeodomain finger protein 8 (PHF8) is upregulated in human PCa tissues and cell lines. PHF8 knockdown attenuates growth and cellular transformation of PCa cells. PHF8 depletion induces PCa cell apoptosis by activating proapoptotic proteins and inactivating antiapoptotic proteins. Furthermore, miR-125b is a target of PHF8, and miR-125b seems to be essential for the hyper proliferation of PCa cells in the presence of PHF8. CONCLUSION: In conclusion, we identify the histone demethylase PHF8 as an oncogenic protein in human PCa. These findings indicate PHF8 as a potential candidate for clinical intervention.

Chlorophyllin e4 is a novel photosensitizer against human bladder cancer cells.

The aim of the study was to investigate the photodynamic effect of the novel photosensitizer chlorophyllin e4 against human bladder cancer cells. T24 and 5637 bladder cancer cell lines were incubated with chlorophyllin e4 and irradiated with a 650-nm laser light. The controls included cells treated with chlorophyllin e4 but without light as well as cells exposed to laser light without chlorophyllin e4. Photocytotoxicity was monitored with MTT assay and apoptosis was measured by flow cytometry. In addition, confocal laser scanning microscopy was used to assess the subcellular localization of chlorophyllin e4. Chlorophyllin e4 exhibited significant photocytotoxicity in both T24 and 5637 cells, which resulted in a maximum of 82.43 and 85.06% cell death, respectively. Treatment with chlorophyllin e4 or laser light alone did not induce cytotoxicity. In addition, chlorophyllin e4-mediated PDT induced a significantly higher percentage of apoptosis in T24 and 5637 cells compared to the control groups (p<0.01). Moreover, confocal laser scanning microscopy revealed that chlorophyllin e4 co-localized with mitochondria in both cell lines. In conclusion, the remarkable photocytotoxicity, natural abundance and inexpensive composition of chlorophyllin e4 suggest that this compound may be a novel, effective photosensitizer for the treatment of human superficial bladder cancer.