Lactate-induced MRP1 expression contributes to metabolism-based etoposide resistance in non-small cell lung cancer cells.

BACKGROUND: Metabolic reprogramming contributes significantly to tumor development and is tightly linked to drug resistance. The chemotherapeutic agent etoposide (VP-16) has been used clinically in the treatment of lung cancer but possess different sensitivity and efficacy towards SCLC and NSCLC. Here, we assessed the impact of etoposide on glycolytic metabolism in SCLC and NSCLC cell lines and investigated the role of metabolic rewiring in mediating etoposide resistance. METHODS: glycolytic differences of drug-treated cancer cells were determined by extracellular acidification rate (ECAR), glucose consumption, lactate production and western blot. DNA damage was evaluated by the comet assay and western blot. Chemoresistant cancer cells were analyzed by viability, apoptosis and western blot. Chromatin immunoprecipitation (ChIP) was used for analysis of DNA-protein interaction. RESULTS: Here we showed that exposure to chemotherapeutic drug etoposide induces an exacerbation of ROS production which activates HIF-1α-mediated the metabolic reprogramming toward increased glycolysis and lactate production in non-small cell lung cancer (NSCLC). We identified lactic acidosis as the key that confers multidrug resistance through upregulation of multidrug resistance-associated protein 1 (MRP1, encoded by ABCC1), a member of ATP-binding cassette (ABC) transporter family. Mechanistically, lactic acid coordinates TGF-ß1/Snail and TAZ/AP-1 pathway to induce formation of Snail/TAZ/AP-1 complex at the MRP1/ABCC1 promoter. Induction of MRP1 expression inhibits genotoxic and apoptotic effects of chemotherapeutic drugs by increasing drug efflux. Furthermore, titration of lactic acid with NaHCO3 was sufficient to overcome resistance. CONCLUSIONS: The chemotherapeutic drug etoposide induces the shift toward aerobic glycolysis in the NSCLC rather than SCLC cell lines. The increased lactic acid in extracellular environment plays important role in etoposide resistance through upregulation of MRP expression. These data provide first evidence for the increased lactate production, upon drug treatment, contributes to adaptive resistance in NSCLC and reveal potential vulnerabilities of lactate metabolism and/or pathway suitable for therapeutic targeting. Video Abstract The chemotherapeutic drug etoposide induces metabolic reprogramming towards glycolysis in the NSCLC cells. The secreted lactic acid coordinates TGF-ß1/Snail and TAZ/AP-1 pathway to activate the expression of MRP1/ABCC1 protein, thus contributing to chemoresistance in NSCLC.

Low Expression MCEMP1 Promoting Lung Adenocarcinoma Progression by and its Clinical Value.

BACKGROUND: Lung cancer is a highly prevalent tumor with a lack of biological markers that reflect its progression. Mast cell surface membrane protein 1 (MCEMP1, also known as C19ORF59) has not been reported in lung adenocarcinoma (LUAD). OBJECTIVE: We aimed to investigate the role of MCEMP1 in LUAD. METHODS: MCEMP1 expression in LUAD was analyzed using The Cancer Genome Atlas (TCGA) data, and conducted univariate and multivariate Cox regression analyses to evaluate the prognostic significance of MCEMP1 expression in TCGA. Tumor Immune Estimation Resource (TIMER) was used for examining the correlation between MCEMP1 expression and immune cell infiltration in LUAD. Furthermore, proliferation, migration, invasion, and colony-forming ability were investigated using LUAD cell lines. RESULTS: MCEMP1 had low expression in LUAD patient tissues and was correlated with lymph node metastasis, differentiation level, and tumor status. The Area under Curve (AUC) value of MCEMP1 for the Receiver Operating Characteristic (ROC) curve analysis was 0.984. The immune infiltration analysis revealed a correlation between MCEMP1 expression and the extent of macrophages and neutrophil infiltration in LUAD. Additionally, MCEMP1 has low expression in clinical samples, MCEMP1 overexpressed in LUAD cells substantially reduced cell growth, migration, and invasion of malignant cells. CONCLUSION: Low expression MCEMP1 promotes LUAD progression, which provides new insights and a potential biological target for future LUAD therapies.

STAMBPL1 promotes the progression of lung adenocarcinoma by inhibiting DHRS2 expression.

BACKGROUND: Lung cancer is responsible for the majority of cancer deaths in the world. We found a significant increase of STAMBPL1 expression in lung adenocarcinoma (LUAD) tissues and cells. However, its mechanism has not been clarified. METHODS: LUAD tissues and adjacent normal tissues were collected from 62 patients treated in the First Affiliated Hospital of Wenzhou Medical University from August 2018 to August 2021. In vivo, the clinical data and STAMBPL1 expression of 62 patients with LUAD were analyzed by qPCR. In vitro, cell experiments were carried out after STAMBPL1 knockdown in A549 and H1299 cells to determine cell growth, migration rate, evasiveness, colony-forming ability, and apoptosis. Gene sequencing was used to explore the expression of various genes in A549 and H1299 cells to verify that DHRS2 was up-regulated after STAMBPL1 knockdown; cell experiments further detected the role of the DHRS2 gene after DHRS2 overexpression in A549 and H1299 cells. A rescue experiment was conducted to certify that STAMBPL1 promotes NSCLC progression by regulating DHRS2 expression. RESULTS: After STAMBPL1 knockdown by siRNA. Migration, invasion, colony formation, and proliferation of siRNA groups were suppressed than those of NC groups in A549 and H1299 cells, while the cell apoptosis rate of siRNA groups increased significantly. By using gene-sequence analysis, we found that the expression level of the DHRS2 gene was up-regulated in STAMBPL1 siRNA groups, compared with STAMBPL1 NC (negative control) groups in A549 and H1299, which was verified by qPCR and WB. Further experiments showed that the DHRS2 OE group was suppressed in cell proliferation, migration, and invasion in the A549 and H1299 cell lines compared to the DHRS2 NC group, while DHRS2 OE group was significantly enhanced in the cell apoptosis in the A549 and H1299 cell lines. According to the rescue experiment, cell proliferation, migration, and invasion of the STAMBPL1 SI+DHRS2 SI group were enhanced compared with the STAMBPL1 SI+DHRS2 NC group in A549 and H1299 cells, while the STAMBPL1 SI+DHRS2 OE group were further decreased. CONCLUSIONS: The expression of STAMBPL1 mRNA is significantly up-regulated in LUAD, promoting the progression of LUAD by down-regulating the expression of DHRS2 and acting as a potential biomarker of LUAD.