miR-7/TGF-β2 axis sustains acidic tumor microenvironment-induced lung cancer metastasis

Acidosis,regardless of hypoxia involvement,is recognized as a chronic and harsh tumor microenvironment(TME)that educates malignant cells to thrive and metastasize.Although overwhelming evidence supports an acidic environment as a driver or ubiquitous hallmark of cancer progression,the unrevealed core mechanisms underlying the direct effect of acidification on tumorigenesis have hindered the discovery of novel therapeutic targets and clinical therapy.Here,chemical-induced and transgenic mouse models for colon,liver and lung cancer were established,respectively.miR-7 and TGF-β2 expressions were examined in clinical tissues(n=184).RNA-seq,miRNA-seq,proteomics,biosynthesis analyses and functional studies were performed to validate the mechanisms involved in the acidic TME-induced lung cancer metastasis.Our data show that lung cancer is sensitive to the increased acidification of TME,and acidic TME-induced lung cancer metastasis via inhibition of miR-7-5 p.TGF-β2 is a direct target of miR-7-5 p.The reduced expression of miR-7-5 p subsequently increases the expression of TGF-β2 which enhances the metastatic potential of the lung cancer.Indeed,overexpression of miR-7-5 p reduces the acidic p H-enhanced lung cancer metastasis.Furthermore,the human lung tumor samples also show a reduced miR-7-5 p expression but an elevated level of activated TGF-β2;the expressions of both miR-7-5 p and TGF-β2 are correlated with patients’survival.We are the first to identify the role of the miR-7/TGF-β2 axis in acidic p H-enhanced lung cancer metastasis.Our study not only delineates how acidification directly affects tumorigenesis,but also suggests miR-7 is a novel reliable biomarker for acidic TME and a novel therapeutic target for non-small cell lung cancer(NSCLC)treatment.Our study opens an avenue to explore the p H-sensitive subcellular components as novel therapeutic targets for cancer treatment.

IKKβ mediates homeostatic function in inflammation via competitively phosphorylating AMPK and IκBα

Inhibitor of nuclear factor kappa-B kinase subunit beta(IKKβ)is one of important kinases in inflammation to phosphorylate inhibitor of nuclear factor kappa-B(IκBα)and then activate nuclear factor kappa-B(NF-κB).Inhibition of IKKβhas been a therapeutic strategy for inflammatory and autoimmune diseases.Here we report that IKKβis constitutively activated in healthy donors and healthy Ikkβ^(C46A)(cysteine 46 mutated to alanine)knock-in mice although they possess intensive IKKβ-IκBα-NF-κB signaling activation.These indicate that IKKβactivation probably plays homeostatic role instead of causing inflammation.Compared to IkkβWTlittermates,lipopolysaccharides(LPS)could induce high mortality rate in Ikkβ^(C46A) mice which is correlated to breaking the homeostasis by intensively activating p-IκBα-NF-κB signaling and inhibiting phosphorylation of 5’adenosine monophosphate-activated protein kinase(p-AMPK)expression.We then demonstrated that IKKβkinase domain(KD)phosphorylates AMPKa1 via interacting with residues Thr183,Ser184,and Thr388,while IKKβhelix-loop-helix motifs is essential to phosphorylate IκBαaccording to the previous reports.Kinase assay further demonstrated that IKKβsimultaneously catalyzes phosphorylation of AMPK and IκBαto mediate homeostasis.Accordingly,activation of AMPK rather than inhibition of IKKβcould substantially rescue LPS-induced mortality in Ikkβ^(C46A) mice by rebuilding the homeostasis.We conclude that IKKβactivates AMPK to restrict inflammation and IKKβmediates homeostatic function in inflammation via competitively phosphorylating AMPK and IκBα.