Protein Kinase CαMediates Erlotinib Resistance in Lung Cancer Cells

Abstract

Overexpression and mutational activation of the epidermal growth factor receptor (EGFR) plays an important role in the pathogenesis of non-small cell lung cancer (NSCLC). EGFR tyrosine-kinase inhibitors (TKIs) are given as a primary therapy for advanced patients with EGFR-activating mutations; however, the majority of these tumors relapse and patients eventually develop resistance to TKIs. To address a potential role of protein kinase C (PKC) isozymes in the resistance to TKIs, we used the isogenic NSCLC H1650 cell line and its erlotinib-resistant derivative H1650-M3, a cell line that displays a mesenchymallike morphology driven by transforming growth factor-b signaling. We found that H1650-M3 cells display remarkable PKCa upregulation and PKCd downregulation. Notably, silencing PKCa from H1650-M3 cells using RNA interference caused a significant reduction in the expression of epithelial-tomesenchymal transition (EMT) markers vimentin, Zeb2, Snail, and Twist. Moreover, pharmacological inhibition or PKCa RNA interference depletion and PKCd restoring sensitized H1650-M3 cells to erlotinib. Whereas ectopic overexpression of PKCa in parental H1650 cells was not sufficient to alter the expression of EMT genes or to confer resistance to erlotinib, it caused downregulation of PKCd expression, suggesting a unidirectional crosstalk. Finally, mechanistic studies revealed that PKCa upregulation in H1650-M3 cells is driven by transforming growth factor-b. Our results identified important roles for specific PKC isozymes in erlotinib resistance and EMT in lung cancer cells, and highlight PKCa as a potential target for lung cancer treatment.

Dasatinib and Doxorubicin Treatment of Sarcoma Initiating Cells: A Possible New Treatment Strategy

“…Furthermore, a combined treatment of EGFR inhibitors and doxorubicin did not increase the efficacy of doxorubicin in killing transformed stromal stem cells. The employed erlotinib concentration has previously reduced cell viability in other cancer cell lines [ 15 ]. Therefore, even though the reduction in cell viability, comparing nontreated and erlotinib treated hMSC-TERT20-CE8, was significant ( p = 0.003), the tumorigenic cell line, in this study, is considered relatively resistant to erlotinib.…”

ML372 blocks SMN ubiquitination and improves spinal muscular atrophy pathology in mice

“…Eluted proteins were run in SDS-PAGE for Western blotting. Western blot analysis was carried out essentially as previously described (48). Briefly, samples were resolved in 10% SDS-PAGE and transferred to polyvinylidene difluoride membranes (Millipore).…”

“…RNA extraction and real-time quantitative PCR (qPCR) were performed as previously described (48). RNA was extracted from subconfluent cell cultures using TRIzol reagent (Invitrogen).…”

Histone Deacetylase-3/CAGE Axis Targets EGFR Signaling and Regulates the Response to Anti-Cancer Drugs

“…6A ), it would be necessary to examine whether CAGE displays kinase activity toward EGFR. PKCα mediates resistance to EGFR inhibitor (erlotinib) and enhances EMT in lung cancer cells ( Abera and Kazanietz, 2015 ). Atypical protein kinase C (aPKC) confers resistance to EGFR inhibitors in gliomas ( Kusne et al, 2014 ).…”