LncRNA MEG3 promotes the sensitivity of vincristine by inhibiting autophagy in lung cancer chemotherapy.

ABSTRACT

OBJECTIVE: Lung cancer is one of the most common malignancies worldwide, the morbidity and mortality of which have been on rising in recent years. Moreover, lncRNAs have been implicated in the development of various cancers, as well as cancer treatment and prognosis. In this study, long non-coding RNA (lncRNA) MEG3, an identified tumor suppressor, was explored for its role in the chemotherapy of lung cancer. MATERIALS AND METHODS: All cases were divided into (I+II) group and (III+IV) group according to different stages of tumor node metastasis (TNM), and were divided into sensitive group and insensitive group according to chemotherapy sensitivity. A549 and H292 cells were selected as the resistant cell and non-resistant lung cancer cells. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was performed to detect the expression of MEG3. After transfection with overexpression plasmid pcDNA-MEG3 or/and different concentrations of vincristine, cell viability and proliferation were measured by cell counting kit-8 (CCK-8) assay and plate cloning assay, respectively. Western blotting was used to analyze the expressions of autophagy-related proteins. RESULTS: In vivo, lncRNA MEG3 was significantly lower in III+IV group and insensitive group than that in I+II group and sensitive group. In vitro, MEG3 expression in resistant cells was significantly lower than that in non-resistant cells. Overexpression of MEG3 significant inhibited the viability and proliferation of both resistant and non-resistant lung cancer cells. Western blot results showed that autophagy level was higher in resistant cells than that in non-resistant cells, while overexpression of MEG3 significantly reduced the expression of autophagy-related proteins. CCK-8 results also indicated that the cell viability was negatively correlated with the dose of vincristine, while the viability of drug-resistant cells was higher than that of non-drug resistant cells after the treatment of vincristine. The vitality of both cells decreased in a concentration-dependent manner after combined treatment with vincristine and MEG3. CONCLUSIONS: Our data indicated that lncRNA MEG3 showed a low expression in chemotherapy-sensitive lung cancer tissues, and overexpression of lncRNA MEG3 attenuated autophagy level, thus increasing the sensitivity of vincristine in chemotherapy of lung cancer.