Human papillomavirus (HPV) type 16 is one of the major etiologic factors of cervical cancer. Our study aims to investigate the potentiality of the antiviral clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated Cas9 system (CRISPR/Cas9) targeting the E6 and E7 oncogenes of HPV16 as a potential chemosensitizer of cisplatin (cis-diaminedichloroplatinum II; CDDP) for cervical cancer. Specifically, the therapeutic efficacy of combination of CDDP and HPV16 E6 + E7-CRISPR/Cas9 was assessed in cervical cancer cells and cervical cancer xenograft models. In vitro experiments showed that long-term exposure of SiHa cells to the HPV16 E6 + E7-CRISPR/Cas9 induced apoptosis, and its pro-apoptosis effect became more obvious when combined with CDDP. In vivo study found the efficacy of the combination of HPV16 E6 + E7-CRISPR/Cas9 and CDDP were superior to either of the treatments in term of apoptosis induction and metastasis inhibition. Collectively, our results suggested that HPV16 E6 + E7-CRISPR/Cas9 could be an effective sensitizer of CDDP chemotherapy in cervical cancer.

Inhibition of long non-coding RNA UCA1 by CRISPR/Cas9 attenuated malignant phenotypes of bladder cancer

Background/Aims: The Warburg effect is one of the main metabolic features for cancers, with long non-coding RNA (lncRNA) being involved as a class of crucial regulators. Our previous studies have shown that ginsenoside 20(S)-Rg3, an active saponin monomer extracted from red ginseng, inhibits the Warburg effect in ovarian cancer cells. However, the detailed lncRNA regulatory network modulated by 20(S)-Rg3 to prevent the Warburg effect in ovarian cancer cells has not been explored. Methods: High-throughput sequencing was used to screen out the differentially expressed lncRNAs between 20(S)-Rg3-treated and non-treated SKOV3 cells. The levels of lncRNA H19 and miR-324-5p were manipulated in SKOV3 and A2780, and the glucose consumption, lactate production and PKM2 protein level were detected. Dual-luciferase reporter assay and RIP were utilized to verify the direct binding of H19 to miR-324-5p and miR-324-5p to PKM2. Cell proliferation was examined by CCK8 and colony formation assay. Nude mice subcutaneous xenograft tumor models were established to evaluate the impact of miR-324-5p on tumor growth in vivo. Results: 20(S)-Rg3 downregulated 67 lncRNAs, and H19 was one of the most decreased lncRNAs. Suppression of H19 by siRNA transfection reduced glucose consumption, lactate production and PKM2 expression in ovarian cancer cells, while H19 overexpression in 20(S)-Rg3-treated ovarian cancer cells enhanced glucose consumption, lactate production and PKM2 expression. Dual-luciferase reporter assay and RIP results showed that H19 directly bound to miR-324-5p. Dual-luciferase reporter assay showed that miR-324-5p directly targeted PKM2, and miR-324-5p negatively regulated glucose consumption and lactate production in ovarian cancer cells. miR-324-5p overexpression inhibited cell proliferation in vitro and in vivo. Conclusion: Our study revealed that 20(S)-Rg3 blocked the competitive inhibition of H19 on miR-324-5p, which enhanced the suppression of miR-324-5p on PKM2 and therefore inhibited the Warburg effect and repressed tumorigenesis. In a word, 20(S)-Rg3 inhibited the Warburg effect in ovarian cancer cells via H19/miR-324-5p/PKM2 pathway.

Background/Aims: The Warburg effect is one of the main energy metabolism features supporting cancer cell growth. 20(S)-Rg3 exerts anti-tumor effect on ovarian cancer partly by inhibiting the Warburg effect. microRNAs are important regulators of the Warburg effect. However, the microRNA regulatory network mediating the anti-Warburg effect of 20(S)-Rg3 was largely unknown. Methods: microRNA deep sequencing was performed to identify the 20(S)-Rg3-influenced microRNAs in SKOV3 ovarian cancer cells. miR-532-3p was overexpressed by mimic532-3p transfection in SKOV3 and A2780 cells or inhibited by inhibitor532-3p transfection in 20(S)-Rg3-treated cells to examine the changes in HK2 and PKM2 expression, glucose consumption, lactate production and cell growth. Dual-luciferase reporter assay was conducted to verify the direct binding of miR-532-3p to HK2. The methylation status in the promoter region of pre-miR-532-3p gene was examined by methylation-specific PCR. Expression changes of key molecules controlling DNA methylation including DNMT1, DNMT3A, DNMT3B, and TET1-3 were examined in 20(S)-Rg3-treated cells. DNMT3A was overexpressed in 20(S)-Rg3-treated cells to examine its influence on miR-532-3p level, HK2 and PKM2 expression, glucose consumption and lactate production. Results: Deep sequencing results showed that 11 microRNAs were increased and 9 microRNAs were decreased by 20(S)-Rg3 in SKOV3 cells, which were verified by qPCR. More than 2-fold increase of miR-532-3p was found in 20(S)-Rg3-treated SKOV3 cells. Forced expression of miR-532-3p reduced HK2 and PKM2 expression, glucose consumption and lactate production in SKOV3 and A2780 ovarian cancer cells. Inhibition of miR-532-3p antagonized the suppressive effect of 20(S)-Rg3 on HK2 and PKM2 expression, glucose consumption and lactate production in ovarian cancer cells. Dual-luciferase reporter assay showed that miR-532-3p directly suppressed HK2 rather than PKM2. miR-532-3p level was controlled by the methylation in the promoter region of its host gene. 20(S)-Rg3 inhibited DNMT3A expression while exerted insignificant effect on DNMT1, DNMT3B and TET1-3. 20(S)-Rg3 reversed DNMT3A-mediated methylation in the promoter of the host gene of miR-532-3p, and thus elevated miR-532-3p level followed by suppression of HK2 and PKM2 expression, glucose consumption and lactate production. Conclusions: 20(S)-Rg3 modulated microRNAs to exert the anti-tumor effect in ovarian cancer. 20(S)-Rg3 lessened the DNMT3A-mediated methylation and promoted the suppression of miR-532-3p on HK2 to antagonize the Warburg effect of ovarian cancer cells.

Abnormal DNA methylation/demethylation is recognized as a hallmark of cancer. TET (ten-eleven translocation) family members are novel DNA demethylation related proteins that dysregulate in multiple malignances. However, their effects on ovarian cancer remain to be elucidated. The changes of TET family members during TGF-β1-induced epithelial-mesenchymal transition (EMT) in SKOV3 and 3AO ovarian cancer cells were detected. TET3 was ectopically expressed in TGF-β1-treated ovarian cancer cells to examine its effect on TGF-β1-induced EMT phenotype. The downstream target of TET3 was further identified. Finally, the relationships of TET3 expression to clinic-pathological parameters of ovarian cancer were investigated with a tissue microarray using immunohistochemistry. TET3 was downregulated during TGF-β1-initiatd epithelial-mesenchymal transition (EMT) in SKOV3 and 3AO ovarian cancer cells. Overexpression of TET3 reversed TGF-β1-induced EMT phenotypes including the expression pattern of molecular markers (E-cadherin, Vimentin, N-cadherin, Snail) and migratory and invasive capabilities of ovarian cancer cells. miR-30d was identified as a downstream target of TET3, and TET3 overexpression resumed the demethylation status in the promoter region of miR-30d precursor gene, resulting in restoration of miR-30d (an EMT suppressor of ovarian cancer cells proven in our previous study) level in TGF-β1-induced EMT. We further found that TET3 expression was decreased in ovarian cancer tissues, especially in serous ovarian cancers. The overall positivity of TET3 was inversely correlated with the grade of differentiation status of ovarian cancer. Our results revealed that TET3 acted as a suppressor of ovarian cancer by demethylating miR-30d precursor gene promoter to block TGF-β1-induced EMT.