Combined effect of ALK and MEK inhibitors in EML4-ALK-positive non-small-cell lung cancer cells.

BACKGROUND: Although most non-small-cell lung cancer (NSCLC) patients with the echinoderm microtubule-associated protein-like 4 (EML4) - anaplastic lymphoma kinase (ALK) fusion gene - benefit from ALK tyrosine kinase inhibitors (ALK-TKIs), the efficacy of these drugs varies greatly among individuals. METHODS: The antitumour action of ALK-TKIs in EML4-ALK-positive NSCLC cell lines was evaluated from their effects on cell proliferation, signal transduction, and apoptosis. RESULTS: The ALK-TKI TAE684 inhibited cell proliferation and induced apoptosis, in association with inhibition of STAT3 and ERK phosphorylation, in EML4-ALK-positive H3122 cells. TAE684 inhibited STAT3 phosphorylation, but not ERK phosphorylation, and it showed little effect on cell proliferation or apoptosis, in EML4-ALK-positive H2228 cells. The combination of TAE684 and a MEK inhibitor-induced marked apoptosis accompanied by inhibition of STAT3 and ERK pathways in H2228 cells. Such dual interruption of STAT3 and ERK pathways induced downregulation of the antiapoptotic protein survivin and upregulation of the proapoptotic protein BIM. CONCLUSION: Our results indicate that interruption of both STAT3-survivin and ERK-BIM pathways is required for induction of apoptosis in NSCLC harbouring EML4-ALK, providing a rationale for combination therapy with ALK and MEK inhibitors in EML4-ALK-positive NSCLC patients for whom ALK inhibitors alone are ineffective.

Marked anti-tumour activity of the combination of YM155, a novel survivin suppressant, and platinum-based drugs.

BACKGROUND: Survivin, a member of the inhibitor of apoptosis protein family, is an attractive target for cancer therapy. We have now investigated the effects of the combination of YM155, a novel small-molecule inhibitor of survivin expression, and platinum compounds (cisplatin and carboplatin) on human non-small cell lung cancer (NSCLC) cell lines. METHODS: The anti-cancer efficacy of YM155 in combination with platinum compounds was evaluated on the basis of cell death and progression of tumour xenografts. Platinum compound-induced DNA damage was evaluated by immunofluorescence analysis of histone gamma-H2AX. RESULTS: Immunofluorescence analysis of histone gamma-H2AX showed that YM155 delayed the repair of double-strand breaks induced in nuclear DNA by platinum compounds. The combination of YM155 and platinum compounds also induced synergistic increases both in the number of apoptotic cells and in the activity of caspase-3. Finally, combination therapy with YM155 and platinum compounds delayed the growth of NSCLC tumour xenografts in nude mice to an extent greater than that apparent with either treatment modality alone. CONCLUSION: These results suggest that YM155 sensitises tumour cells to platinum compounds both in vitro and in vivo, and that this effect is likely attributable to the inhibition of DNA repair and consequent enhancement of apoptosis.

Enhancement of the antitumor activity of ionising radiation by nimotuzumab, a humanised monoclonal antibody to the epidermal growth factor receptor, in non-small cell lung cancer cell lines of differing epidermal growth factor receptor status.

The expression and activity of the epidermal growth factor receptor (EGFR) are determinants of radiosensitivity in several tumour types, including non-small cell lung cancer (NSCLC). However, little is known of whether genetic alterations of EGFR in NSCLC cells affect the therapeutic response to monoclonal antibodies (mAbs) to EGFR in combination with radiation. We examined the effects of nimotuzumab, a humanised mAb to EGFR, in combination with ionising radiation on human NSCLC cell lines of differing EGFR status. Flow cytometry revealed that H292 and Ma-1 cells expressed high and moderate levels of EGFR on the cell surface, respectively, whereas H460, H1299, and H1975 cells showed a low level of surface EGFR expression. Immunoblot analysis revealed that EGFR phosphorylation was inhibited by nimotuzumab in H292 and Ma-1 cells but not in H460, H1299, or H1975 cells. Nimotuzumab augmented the cytotoxic effect of radiation in H292 and Ma-1 cells in a clonogenic assay in vitro, with a dose enhancement factor of 1.5 and 1.3, respectively. It also enhanced the antitumor effect of radiation on H292 and Ma-1 cell xenografts in nude mice, with an enhancement factor of 1.3 and 4.0, respectively. Nimotuzumab did not affect the radioresponse of H460 cells in vitro or in vivo. Nimotuzumab enhanced the antitumor efficacy of radiation in certain human NSCLC cell lines in vitro and in vivo. This effect may be related to the level of EGFR expression on the cell surface rather than to EGFR mutation.

Induction of MRP5 and SMRP mRNA by adriamycin exposure and its overexpression in human lung cancer cells resistant to adriamycin.

Acquired anticancer drug resistance in cancer cells is often a result of an increase in levels of the ATP binding cassette (ABC) transporters that export anticancer drugs from cancer cells, suggesting that anticancer drugs may induce genes that mediate drug resistance in cancer cells. In this study, the induction of anticancer drug transporter gene expression by Adriamycin was examined in human lung cancer cell lines. Increased expression of MDR1, MRP5 and SMRP mRNA was observed 48 hr after the initiation of Adriamycin exposure in human lung cancer PC-14 cells and cisplatin-resistant PC-14/CDDP cells, in a dose-dependent manner as measured by TaqMan real-time RT-PCR. The levels of MRP-1, MRP2 and LRP mRNA were not altered by Adriamycin exposure. The biologic functions of the MRP5 and SMRP genes have not been fully clarified. To elucidate the relationship between Adriamycin resistance and MRP5 and SMRP, mRNA levels of MRP5 and SMRP in Adriamycin-resistant cell lines were compared with the parental cells. Increased expression of MRP5 and SMRP mRNA was observed in all 3 cell lines (SBC-3/ADM, AdR MCF7 and K562/ADM) by Northern blot analysis and RNase protection assay. These results suggest that subacute exposure of lung cancer cells to Adriamycin induced MRP5 and SMRP and that long-term exposure with Adriamycin selected the MRP5- and SMRP-overexpressing lung cancer cells. MRP5 and SMRP is a candidate molecule for acquired Adriamycin resistance in addition to MDR1.