casein-kinase-ii and icotinib

The abnormal activation of the downstream signaling pathways of epidermal growth factor receptor (EGFR) that are independent of EGFR, contribute to the acquisition of EGFR‑tyrosine kinase inhibitor (TKI) resistance in non‑small cell lung cancer (NSCLC). The serine/threonine protein kinase casein kinase II (CK2) phosphorylates and modulates several members of the EGFR downstream signaling pathways. Thus, the purpose of the current study was to investigate the effects of the addition of quinalizarin (a specific CK2 inhibitor) to icotinib (an EGFR‑TKI) on the proliferation and apoptosis of four NSCLC cell lines and its underlying mechanisms. The human lung adenocarcinoma cell lines HCC827, A549, H1650 and H1975 were employed to represent the EGFR‑TKI‑sensitive EGFR (EGFR‑sensitive) mutation, wild‑type EGFR and the EGFR‑TKI‑resistant EGFR (EGFR‑resistant) mutations. The cell viability was determined by the MTT assay. Cell apoptosis was detected by flow cytometry using the Annexin V‑enhanced green fluorescent protein Apoptosis Detection kit. The level of proteins in the EGFR downstream pathway was observed using a western blot assay. The results showed that the cells with the EGFR‑sensitive mutation (HCC827, EGFR E716‑A750del) were more sensitive to icotinib compared with those possessing the EGFR wild‑type (A549) and the EGFR‑resistant mutations (H1650, EGFR E716‑A750del and PTEN lost; H1975, EGFR L858R+T790M). Quinalizarin inhibited proliferation and promoted apoptosis in the cells with the EGFR wild‑type and resistant mutations, and the addition of quinalizarin to icotinib partially restored their sensitivity to icotinib. Quinalizarin and/or icotinib increased the apoptotic rates in the EGFR‑TKI resistant cells, and the combination of these reduced the level of protein downstream of EGFR, including phosphorylated (p‑AKT) and p‑(ERK). In conclusion, quinalizarin may partially sensitize cells to icotinib by inhibiting proliferation and promoting apoptosis mediated by AKT and ERK in EGFR‑TKI resistant NSCLC cell lines.

Topics: Adenocarcinoma of Lung; Anthraquinones; Antineoplastic Agents; Apoptosis; Casein Kinase II; Cell Line, Tumor; Cell Proliferation; Crown Ethers; Drug Resistance, Neoplasm; Humans; Lung Neoplasms; Protein Kinase Inhibitors; Quinazolines

To explore whether quninalizarin, an specific inhibitor of protein kinase CK2, could sensitize icotinib in EGFR-TKIs (epithelial growth factor receptor-tyrosine kinase inhibitor)-resistant cell lines and uncover the underlying mechanisms.. MTT assay was performed to evaluate the inhibitory effect of quninalizarin, icotinib or the combination of both on cell proliferation in several lung adenocarcinoma cell lines. Western blot assay was used to assess if combined inhibition of EGFR and protein kinase CK2 by icotinib and quninalizarin, exerts effect on the expression and phosphorylation of major proteins of EGFR signaling pathways.. The IC50 of HCC827, H1650, H1975 and A549 cells for icotinib were (8.07±2.00)μmol/L, (66.01±6.64)μmol/L, (265.60±9.47)μmol/L and (87.88±6.8)μmol/L, respectively, indicating that HCC827 cells are sensitive to icotinib, and the H1650, H1975 and A549 cells are relatively resistant to icotinib. When treated with both quninalizarin and icotinib in the concentration of 50 μmol/L, the viability of H1650, H1975 and A549 cells was (40.64±3.73)%, (65.74±3.27)% and (44.96±0.48)%, respectively, significantly lower than that of H1650, H1975 and A549 cells treated with 50 μmol/L icotinib alone (55.05±1.22)%, (71.98±1.60)% and (61.74±6.18)%, respectively (P<0.01 for all). When treated with both 100 μmol/L quninalizarin and 100 μmol/L icotinib, the viability of H1650, H1975 and A549 ells were (23.35±0.81)%, (55.70±1.03)%, (33.42±1.33)%, respectively, significantly lower than the viability of H1650, H1975 and A549 cells treated with 100 μmol/L icotinib alone (40.57±2.65)%, (62.40±2.05)% and (44.97±8.20)%, respectively, (P<0.01 for all). The two-way ANOVA analysis showed that compared with the viability of EGFR-TKIs-resistant cells (H1650, H1975, A549) treated with 50 μmol/L and 100 μmol/L icotinib alone, the viability of cells treated with icotinib and quinalizarin were significantly suppressed, and the differences were statistically significant (P<0.01). In addition, the phosphorylation form of Akt and ERK (namely p-Akt and p-ERK) were significantly down-regulated by treating with quninalizarin and icotinib together in the H1650 cells while the expression of Akt and ERK changed little.. Quinalizarin, as a specific CK2 inhibitor, may overcome icotinib resistance by inhibiting proliferation mediated by Akt and ERK in human lung adenocarcinoma cell lines, and enhances the suppressive effect of icotinib on the proliferation of EGFR-TKIs-resistant human lung adenocarcinoma cells.

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Analysis of Variance; Anthraquinones; Apoptosis; Casein Kinase II; Cell Line, Tumor; Cell Proliferation; Cell Survival; Crown Ethers; Down-Regulation; Drug Combinations; Drug Resistance, Neoplasm; Drug Synergism; ErbB Receptors; Humans; Lung Neoplasms; Phosphorylation; Protein-Tyrosine Kinases; Quinazolines; Signal Transduction