Study For The Functional Role And Regulation Mechanism Of MiR-31-5p In Cancer Cell Energy Metabolism Mode Determination

Adequate energy and nutrient supply are the basis of cancer cell growth,invasion and metastasis.Abnormal energy metabolism is the most significant hallmark of cancer cells.There are two main metabolism modes in cells that one is oxidative phosphorylation(OXPHOS)occurs in mitochondrion,the other one is glycolysis which takes place in cytosolic.In normal tissue,cells use OXPHOS as the main mode to produce energy,while cancer cells use glycolysis,Warburg effect,for the ATP production by reprogramming energy metabolism.Hemopoietic stem cells(HSCs)exist in the bone marrow niche that is a hypoxic microenvironment,and depend on glycolysis pathway producing energy without the involvement of oxygen.Contrary to normal HSCs,recent studies showed that the leukemia stem cells(LSCs)alter the metabolism mode and only rely on OXPHOS producing energy.So far,it remains unclear how cancer cells to determine and regulate the alternation of energy metabolism modes.The alternative expression of mi R-31-5p has been observed in many human malignancies and this mi RNA regulates several aspects of oncogenesis in different type of cells upon up-regulation or down-regulation.However,the role of mi R-31-5p in cellular energy metabolism remains elusive.We found that the expression of mi R-31-5p is up-regulation in solid tumor cells,including lung cancer cells,but loss in LSCs,suggesting that the expression profile of mi R-31-5p is somewhat related to the selection of energy metabolism mode in cancer cells.To thoroughly investigate the function of mi R-31-5p on cells metabolism mode,we first took two solid tumor cells lines,H1299 and A549(lung cancer cell lines),as research model.mi R-31-5p directly targets hypoxia inducible factor 1 inhibitor(FIH),further regulating the transactivation of hypoxia inducible factor 1(HIF-1?).In H1299 and A549 cells(lung cancer cell lines),mi R-31-5p overexpression down-regulates FIH expression and increases the activity of HIF-1? and the expression of HIF-targeted glycolytic genes,GLUT-1,GAPDH,LDH-A included,thus enhancing glycolysis pathway(the increased lactic acid and ATP production)and cells proliferation.We combined manipulation of mi R-31-5p with that of FIH,all the effects above were rescued.By contrast,mi R-31-5p inhibition up-regulates FIH expression and inhibits the activity of HIF-1? and the expression of HIF-targeted glycolytic genes,further inhibits glycolysis and cell proliferation.All the effects can be reversed upon mi R-31-5p inhibition plus FIH knockdown.Finally,by hiring A549 cell xenograft mouse model,we demonstrate that the mi R-31-5p promotes cell proliferation via enhancing Warburg effect.Taken together,this study reveals that mi R-31-5p promotes energy production by mean of Warburg effect via direct targeting of FIH,further regulating the activity of HIF-1? and its targeted glycolytic genes expression.Next,we took acute myelocytic leukemia(AML)-leukemia stem cells(LSCs)as oxidative phosphorylation(OXPHOS)metabolism cell model,whereas hemopoietic stem cell(HSCs)as the control,to study the role of mi R-31-5p in energy metabolism.By comparison,we found that mi R-31-5p is highly expressed in HSCs,but loss in the DNA encoding region in LSCs.Compared with HSCs,the expression of FIH in LSCs is increased and the activity of HIF-1? and the expression of HIF-targeted glycolytic genes are decreased,resulting in the activated pyruvate dehydrogenase complex(PDC).In LSCs,mi R-31-5p inhibits FIH expression and increases the transactivation of HIF-1?,but decreases PDC activity and inhibits OXPHOS.Manipulation of mi R-31-5p with that of FIH,all the effects above were rescued.In HSCs,knockdown of mi R-31-5p increases the expression of FIH,inhibits the transactivation of HIF-1?,the activity of PDC and OXPHOS.All the effects can be reversed upon mi R-31-5p inhibition plus FIH knockdown.Last,the findings show that overexpression of mi R-31-5p in LSCs induces cell death,while inhibition of mi R-31-5p in HSCs impairs cell clones,indicating that the energy metabolism modes under the control of mi R-31-5p have an important effect on biological behavior of stem cells.In conclusion,mi R-31-5p regulates HIF signaling and HIF-targeted genes expression via targeting FIH.mi R-31-5p acts as a switch of metabolism,which maintains cellular energy metabolism.Therefore,in some cancer cells expressed mi R-31-5p,Warburg effect is the main metabolism mode,whereas in some cancer cells lost mi R-31-5p,OXPHOS is a predominantly energy metabolism mode.