Upregulation of miR-136 in human non-small cell lung cancer cells promotes Erk1/2 activation by targeting PPP2R2A
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MicroRNAs (miRNAs) have been integrated into cancer development and progression, because they repress translation of target genes which can be tumor suppressors and oncogenes. A number of miRNAs have been found to be closely related to human non-small cell lung cancer (NSCLC). However, the roles of miR-136 in NSCLC are still largely unknown. Here, we show that miR-136 is significantly upregulated in human NSCLC primary tumors and cell lines compared to their nontumor counterparts. Suppression of miR-136 expression in NSCLC cell line A549 inhibited both anchorage-dependent and anchorage-independent proliferation. Further studies showed that suppression of miR-136 expression attenuated phosphorylation of extracellular-signal-regulated kinase 1/2 (Erk1/2). We found that serine/threonine protein phosphatase 2A 55 kDa regulatory subunit B α isoform (PPP2R2A, also known as B55α) was a direct target of miR-136, and suppression of miR-136 expression led to a robust increase in both mRNA and protein levels of PPP2R2A. We found that miR-136 promoted phosphorylation of Erk1/2 through inhibition of PPP2R2A expression, and forced overexpression of PPP2R2A abrogated promotion of Erk1/2 phosphorylation by miR-136. Moreover, forced overexpression of PPP2R2A abrogated the promoting effect of miR-136 on cell growth and led to a reduced growth rate of NSCLC cells. Our findings indicate that miR-136 promotes Erk1/2 phosphorylation through targeting PPP2R2A in NSCLC cells and suggest that it may serve as a therapeutic target in NSCLC therapy.
KeywordsmiR-136 Non-small cell lung cancer (NSCLC) Cell proliferation Extracellular-signal-regulated kinase 1/2 (Erk1/2) Serine/threonine protein phosphatase 2A 55 kDa regulatory subunit B α isoform (PPP2R2A)
This work was supported by the National Natural Science Foundation of China (no. 91071909).
Conflicts of interest
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