175P Mutations and clinical significance of calcium voltage-gated channel subunit alpha 1E (CACNA1E) in non-small cell lung cancer

CACNA1E is a gene encoding the ion-conducting α1 subunit of R-type voltage-dependent calcium channels. We previously showed that CACNA1E was significantly mutated in patients with non-small cell lung cancer (NSCLC) who were long-term exposed to household air pollution, with a mutation rate of 19% (15 of 79 cases). However, the roles for CACNA1E to play in lung tumorigenesis remain largely unknown. We analyzed the mutation rates and expression of CACNA1E in The Cancer Genome Atlas (TCGA) lung cancer datasets and NSCLC patients samples. The effect of wild type (WT) or A275S or R249G mutant CACNA1E on tumor cell growth was detected by foci formation assay and InCucyte imaging analysis. WT or mutant CACNA1E-mediated Akt, Erk1/2 and EGFR phosphorylation were detected by Western blotting. To assess the Ca2+ influx through CACNA1E, we used whole-cell patch-clamp recording experiment. Ca2+ basal concentration was tested by calcium indicator Fura-2 AM, Fluo-4 AM or transfection of pCDNA3.1-mKate-linker-GCaMP6m. CACNA1E-knockdown cells were employed for examining the proliferative capacity of tumor cells in vitro and in vivo. We showed that CACNA1E was also mutated in 207 (12.8%) of the 1616 patients with NSCLC in TCGA datasets. At mRNA and protein levels, CACNA1E was elevated in tumor tissues compared to counterpart non-tumoral lung tissues in NSCLCs of the public datasets and our settings, and its expression level was inversely associated with clinical outcome of the patients. Overexpression of WT or A275S or R249G mutant CACNA1E transcripts promoted NSCLC cell proliferation with activation of EGFR signaling pathway, whereas knockdown of this gene exerted inhibitory effects on NSCLC cells in vitro and in vivo. CACNA1E increased current density and Ca2+ entrance, whereas calcium channel blockers inhibited NSCLC cell proliferation. These data indicate that CACNA1E is required for NSCLC cell proliferation, and blockade of this oncoprotein may have therapeutic potentials for this deadly disease.