Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal human cancers. It thrives in a malnourished environment; however, little is known about the mechanisms by which PDAC cells actively promote aerobic glycolysis to maintain their metabolic needs. Gene Expression Omnibus (GEO) was used to identify differentially expressed miRNAs. The expression pattern of miR-30d in normal and PDAC tissues was studied by in situ hybridization. The role of miR-30d/RUNX1 in vitro and in vivo was evaluated by CCK8 assay and clonogenic formation as well as transwell experiment, subcutaneous xenograft model and liver metastasis model, respectively. Glucose uptake, ATP and lactate production were tested to study the regulatory effect of miR-30d/RUNX1 on aerobic glycolysis in PDAC cells. Quantitative real-time PCR, western blot, Chip assay, promoter luciferase activity, RIP, MeRIP, and RNA stability assay were used to explore the molecular mechanism of YTHDC1/miR-30d/RUNX1 in PDAC. Here, we discover that miR-30d expression was remarkably decreased in PDAC tissues and associated with good prognosis, contributed to the suppression of tumor growth and metastasis, and attenuation of Warburg effect. Mechanistically, the m6A reader YTHDC1 facilitated the biogenesis of mature miR-30d via m6A-mediated regulation of mRNA stability. Then, miR-30d inhibited aerobic glycolysis through regulating SLC2A1 and HK1 expression by directly targeting the transcription factor RUNX1, which bound to the promoters of the SLC2A1 and HK1 genes. Moreover, miR-30d was clinically inversely correlated with RUNX1, SLC2A1 and HK1, which function as adverse prognosis factors for overall survival in PDAC tissues. Overall, we demonstrated that miR-30d is a functional and clinical tumor-suppressive gene in PDAC. Our findings further uncover that miR-30d is a novel target for YTHDC1 through m6A modification, and miR-30d represses pancreatic tumorigenesis via suppressing aerobic glycolysis.

Chemoresistance is responsible for most colorectal cancer (CRC) related deaths. In this study, we found that dichloroacetate (DCA), a pyruvate dehydrogenase kinase (PDK) inhibitor, can be used as a sensitizer for oxaliplatin (L-OHP) chemoresistant CRC cells. The aim of this study was to explore the ability of DCA to overcome L-OHP resistance in CRC cells and to identify the underlying molecular mechanisms. We found that DCA sensitizes chemoresistant CRC cells to L-OHP-induced cytotoxic effects by inhibiting clone formation capacity and promoting cell apoptosis. A microRNA (miRNA) array was used for screen, and miR-543 was identified and shown to be downregulated after DCA treatment. The expression of miR-543 was higher in chemoresistant CRC cells than in chemosensitive CRC cells. Overexpression of miR-543 increased chemoresistance in CRC cells. The validated target gene, PTEN, was negatively regulated by miR-543 both in vitro and in vivo, and PTEN was upregulated by DCA through miR-543. In addition, overexpression of miR-543 reversed the inhibition of colony formation after DCA treatment. Furthermore, the Akt/mTOR pathway is activated by miR-543 and is involved in the miR-543 induced chemoresistance. There was a significant inverse relationship between miR-543 expression and PTEN level in CRC patients, and high miR-543 expression was associated with worse prognosis. In conclusion, DCA restored chemosensitivity through miR-543/PTEN/Akt/mTOR pathway, and miR-543 may be a potential marker or therapeutic target for chemoresistance in CRC.

The development of chemoresistance remains a major challenge that accounts for colorectal cancer (CRC) lethality. Dichloroacetate (DCA) was originally used as a metabolic regulator in the treatment of metabolic diseases; here, DCA was assayed to identify the mechanisms underlying the chemoresistance of CRC. We found that DCA markedly enhanced chemosensitivity of CRC cells to fluorouracil (5-FU), and reduced the colony formation due to high levels of apoptosis. Using the microarray assay, we noted that miR-149-3p was involved in the chemoresistance of CRC, which was modulated by wild-type p53 after DCA treatment. In addition, PDK2 was identified as a direct target of miR-149-3p. Mechanistic analyses showed that overexpression of miR-149-3p enhanced 5-FU-induced apoptosis and reduced glucose metabolism, similar to the effects of PDK2 knockdown. In addition, overexpression of PDK2 partially reversed the inhibitory effect of miR-149-3p on glucose metabolism. Finally, both DCA treatment and miR-149-3p overexpression in 5-FU-resistant CRC cells were found to markedly sensitize the chemotherapeutic effect of 5-FU in vivo, and this effect was also validated in a small retrospective cohort of CRC patients. Taken together, we determined that the p53/miR-149-3p/PDK2 signaling pathway can potentially be targeted with DCA treatment to overcome chemoresistant CRC.