KRAS-mutation status dependent effect of zoledronic acid in human non-small cell cancer preclinical models

Abstract

BackgroundIn non-small cell lung cancer (NSCLC) KRAS-mutant status is a negative prognostic and predictive factor. Nitrogen-containing bisphosphonates inhibit prenylation of small G-proteins (e.g. Ras, Rac, Rho) and thus may affect proliferation and migration. In our preclinical work, we investigated the effect of an aminobisphosphonate compound (zoledronic acid) on mutant and wild type KRAS-expressing human NSCLC cell lines.ResultsWe confirmed that zoledronic acid was unable to inhibit the prenylation of mutant K-Ras unlike in the case of wild type K-Ras. In case of in vitro proliferation, the KRAS-mutant human NSCLC cell lines showed resistance to zoledronic acid wild-type KRAS-cells proved to be sensitive. Combinatory application of zoledronic acid enhanced the cytostatic effect of cisplatin. Zoledronic acid did not induce significant apoptosis. In xenograft model, zoledronic acid significantly reduced the weight of wild type KRAS-EGFR-expressing xenograft tumor by decreasing the proliferative capacity. Futhermore, zoledronic acid induced VEGF expression and improved in vivo tumor vascularization.Materials and methodsMembrane association of K-Ras was examined by Western-blot. In vitro cell viability, apoptotic cell death and migration were measured in NSCLC lines with different molecular background. The in vivo effect of zoledronic acid was investigated in a SCID mouse subcutaneous xenograft model.ConclusionsThe in vitro and in vivo inhibitory effect of zoledronic acid was based on the blockade of cell cycle in wild type KRAS-expressing human NSCLC cells. The zoledronic acid induced vascularization supported in vivo cytostatic effect. Our preclinical investigation suggests that patients with wild type KRAS-expressing NSCLC could potentially benefit from aminobisphosphonate therapy.

Prognostic effects of osteoclast inhibitors in extensive stage small cell lung cancer patients with bone metastases

“…Although the incidence of SREs was not decreased by OIs in the present SCLC patients with BM, likely reflecting retrospective treatments, new incidences of SREs were observed in 10 of the 23 OIs treated patients, suggesting that OIs prolong survival via a mechanism that is independent of the suppression of SREs. In agreement, Zol reportedly suppressed the proliferation of SCLC cell lines in vitro and in vivo (17,18), and these antitumor effects of Zol were associated with inhibition of farnesylation and geranylgeranylation of RAS related proteins, and the induction of apoptosis (17). Zol also showed synergistic effects with other anti-cancer agents, such as cisplatin, etoposide and irinotecan in vitro (19)(20)(21), and a recent preclinical study showed that Zol promotes the maturation of γδ T cells and contributes to antitumor immune responses (22).…”

Current therapy of KRAS-mutant lung cancer

“…Notably, however, a recent preclinical study demonstrated that the aminobisphosphonate compound zoledronic acid was ineffective in NSCLC cells harboring exon 2 codon 12 KRAS mutation, since this mutational subtype leads to prenylation-independent activation of KRAS. [80]. Nevertheless, the impact of the bisphosphonate treatment in KRAS-mutant LADC patients remains to be fully explored.…”

Anti-Tumor Effects of Low Dose Zoledronate on Lung Cancer-Induced Spine Metastasis

“…Under these conditions, 1, 3 and 10 µM Zol significantly slows down the proliferation at a range of 20 to 80% for all cell types with BML4 having the highest sensitivity. These Zol doses were up to 100 times less than the concentrations previously used to decrease proliferation of human NSCLC including HCC827 and SCLC cell lines (in vitro for less than 5 days) [35,36,37,45]. In all these studies, the impaired proliferation was attributed either to an increase in cell apoptosis or to a disruption of cell cycle [35,36,37,45].…”

“…These Zol doses were up to 100 times less than the concentrations previously used to decrease proliferation of human NSCLC including HCC827 and SCLC cell lines (in vitro for less than 5 days) [35,36,37,45]. In all these studies, the impaired proliferation was attributed either to an increase in cell apoptosis or to a disruption of cell cycle [35,36,37,45]. Moreover, it was suggested that bisphosphonates promote apoptosis in the bone-colonizing cancer cells as a result of restricting the supply of bone-stored growth factors that are crucial for the proliferation and survival of cancer cells following the inhibition of osteoclastic bone resorption [46,47,48,49,50,51].…”