[Overexpression of leukemia inhibitory factor enhances chemotherapy tolerance of endometrial cancer cells in vitro].

OBJECTIVE: To investigate the effect of overexpression of leukemia inhibitory factor (LIF) on cisplatin and paclitaxel resistance of endometrial cancer cells in vitro. METHODS: Endometrial cancer cell lines HEC-1B and RL95-2 were infected with a recombinant lentivirus to overexpress LIF, and the changes in LIF expression was verified using RT-qPCR and ELISA. The viability of the LIF-overexpressing cells was assessed using CCK-8 assay, and the cell apoptosis and changes in mitochondrial membrane potential in response to cisplatin or paclitaxel treatment were analyzed with annexin V-FITC/PI staining and JC-1 assay, respectively. The effect of LIF overexpression on the expressions of Bcl-2 family proteins and STAT3 pathway was evaluated using Western blotting; dual-luciferase reporter gene assay was employed to detect the transcriptional activity of STAT3. The effect of STAT3 silencing on apoptosis of the LIF-overexpressing cells induced by cisplatin or paclitaxel was investigated. RESULTS: The cell lines infected with the recombinant lentivirus showed significantly increased mRNA and protein levels of LIF (P < 0.05) without obvious changes in the cell viability (P>0.05). LIF overexpression significantly attenuated cisplatin-or paclitaxel-induced apoptosis of the endometrial cancer cells (P < 0.05) and markedly increased mitochondrial membrane potential of the cells (P < 0.05). The expressions of Bcl-2, Bcl-xL and p-STAT3 proteins increased obviously while the expressions of Bax, Bad and STAT3 either decreased or showed no obvious changes in the LIF-overexpressing cells. Overexpressing LIF significantly enhanced the transcriptional activity of STAT3 (P < 0.05), and silencing STAT3 obviously enhanced apoptosis of the endometrial cancer cells overexpressing LIF (P < 0.05). CONCLUSIONS: s Overexpression of LIF can enhance cisplatin and paclitaxel resistance to endometrial cancer cells in vitro.

Silencing LGR6 Attenuates Stemness and Chemoresistance via Inhibiting Wnt/ß-Catenin Signaling in Ovarian Cancer.

Leucine-rich-repeat-containing G protein-coupled receptors (LGRs) have been widely found to be implicated with development and progression in multiple cancer types. However, the clinical significance and biological functions of LGR6 in ovarian cancer remains unclear. In this study, LGR6 expression was mainly examined by immunohistochemistry. Functional assays in vitro and animal experiments in vivo were carried out to explore the effect of LGR6 on cancer stem cell (CSC) characteristics and chemotherapeutic responses in ovarian cancer cells. Luciferase assays and GSEA were used to discern the underlying mechanisms contributing to the roles of LGR6 in ovarian cancer. Here, we reported that LGR6 was upregulated in ovarian cancer, which positively correlated with poor chemotherapeutic response and progression survival in ovarian cancer patients. Loss-of-function assays showed that downregulating LGR6 abrogated the CSC-like phenotype and chemoresistance in vitro. More importantly, silencing LGR6 improved the chemoresistance of ovarian cancer cells to cisplatin in vivo. Mechanistic investigation further revealed that silencing LGR6 inhibited stemness and chemoresistance by repressing Wnt/ß-catenin signaling. Collectively, our results uncover a novel mechanism contributing to LGR6-induced chemotherapeutic resistance in ovarian cancer, providing the evidence for LGR6 as a potential therapeutic target in ovarian cancer.

Phospholipid Phosphatase 4 promotes proliferation and tumorigenesis, and activates Ca2+-permeable Cationic Channel in lung carcinoma cells.

BACKGROUND: Phospholipid phosphatase 4 (PPAPDC1A or PLPP4) has been demonstrated to be involved in the malignant process of many cancers. The purpose of this study was to investigate the clinical significance and biological roles of PLPP4 in lung carcinoma. METHODS: PLPP4 expression was examined in 8 paired lung carcinoma tissues by real-time PCR and in 265 lung carcinoma tissues by immunohistochemistry (IHC). Statistical analysis was performed to evaluate the clinical correlation between PLPP4 expression and clinicopathological features and survival in lung carcinoma patients. In vitro and in vivo assays were performed to assess the biological roles of PLPP4 in lung carcinoma. Fluorescence-activated cell sorting, Western blotting and luciferase assays were used to identify the underlying pathway through which PLPP4 silencing mediates biological roles in lung carcinoma. RESULTS: PLPP4 is differentially elevated in lung adenocarcinoma (ADC) and lung squamous cell carcinoma (SQC) tissues. Statistical analysis demonstrated that high expression of PLPP4 significantly and positively correlated with clinicopathological features, including pathological grade, T category and stage, and poor overall and progression-free survival in lung carcinoma patients. Silencing PLPP4 inhibits proliferation and cell cycle progression in vitro and tumorigenesis in vivo in lung carcinoma cells. Our results further reveal that PLPP4 silencing inhibits Ca2+-permeable cationic channel, suggesting that downregulation of PLPP4 inhibits proliferation and tumorigenesis in lung carcinoma cells via reducing the influx of intracellular Ca2+. CONCLUSION: Our results indicate that PLPP4 may hold promise as a novel marker for the diagnosis of lung carcinoma and as a potential therapeutic target to facilitate the development of novel treatment for lung carcinoma.

Maintenance of cancer stemness by miR-196b-5p contributes to chemoresistance of colorectal cancer cells via activating STAT3 signaling pathway.

Emerging studies indicated that cancer stem cells represent a subpopulation of cells within the tumor that is responsible for chemotherapeutic resistance. However, the underlying mechanism is still not clarified yet. Here we report that miR-196b-5p is dramatically upregulated in CRC tissues and high expression of miR-196b-5p correlates with poor survival in CRC patients. Moreover, recurrent gains (amplification) contribute to the miR-196b-5p overexpression in CRC tissues. Silencing miR-196b-5p suppresses spheroids formation ability, the fraction of SP cells, expression of stem cell factors and the mitochondrial potential, and enhances the apoptosis induced by 5-fluorouracil in CRC cells; while ectopic expression of miR-196b-5p yields an opposite effect. In addition, downregulation of miR-196b-5p resensitizes CRC cells to 5-fluorouracil in vivo. Our results further demonstrate that miR-196b-5p promotes stemness and chemoresistance of CRC cells to 5-fluorouracil via targeting negative regulators SOCS1 and SOCS3 of STAT3 signaling pathway, giving rise to activation of STAT3 signaling. Interestingly, miR-196b-5p is highly enriched in the serum exosomes of patients with CRC compared to the healthy control subjects. Thus, our results unravel a novel mechanism of miR-196b-5p implicating in the maintenance of stem cell property and chemotherapeutic resistance in CRC, offering a potential rational registry of anti-miR-196b-5p combining with conventional chemotherapy against CRC.