Bioengineered microRNAs in the control of folate cycle related one‐carbon metabolism in NSCLC metabolism

Abstract

Lung cancer remains as the leading cause of cancer deaths in the US and worldwide, of which non-small cell lung cancer (NSCLC) accounts for 80-85%. Very recently, we have established a novel technology to achieve in vivo fermentation production of bioengineered miRNA agents for the study of cancer biology and new therapies. Using recombinant miRNA molecules produced and folded in living cells, a number of the top most effective miRNAs against NSCLC cell variability were identified, among which miR-22-3p, miR-9-5p and miR-218-5p were all predicted to interfere with folate cycle of one-carbon metabolism. The serine hydroxymethyltransferase-1 (SHMT-1), a tumor biomarker and important enzyme in folate biotransformation, was verified as a new target for both miR-9-5p and miR-218-5p. The methylenetetrahydrofolate dehydrogenase 1 like (MTHFD1L) and methylenetetrahydrofolate dehydrogenase-2 (MTHFD2) were proven to be regulated by miR-9-5p directly. Furthermore, both methylenetetrahydrofolate reductase (MTHFR) and MTHFD2 were significantly suppressed by miR-22-3p in NSCLC cells. LC-MS/MS methods revealed that folate metabolites and amino acid metabolome were altered remarkably by individual miRNAs in human NSCLC cells. Further isotope labeled glucose feeding experiments showed that miR-22-3p affected intracellular supply of serine through the inhibition of glucose transporter GLUT1, and miR-9-5p and miR-218-5p decreased serine levels via downregulation of serine biosynthesis enzymes. Consequently, glycolytic rate and mitochondrial function were significantly inhibited in NSCLC cells by these miRNAs, accompanied by cell cycle arrest, ROS accumulation and NADP+/NADPH imbalance. Finally, miR-22-3p-loaded lipopolyplex was shown to significantly inhibit tumor growth in NSCLC patient-derived xenograft (PDX) mouse models in vivo, attributable to on-target actions. In conclusion, the study demonstrates that bioengineered miR-22-3p, miR-9-5p, and miR-218-5p act on folate cycle to suppress NSCLC cell metabolism, among which miR-22-3p is effective to control NSCLC tumor growth in PDX mice. These findings provide new insights into mechanistic actions of tumor suppressive miRNAs and development of new therapeutic strategies for NSCLC.