Original article: general thoracic
Enhancement of paclitaxel-mediated cytotoxicity in lung cancer cells by 17-allylamino geldanamycin: in vitro and in vivo analysis

Presented at the Thirty-seventh Annual Meeting of The Society of Thoracic Surgeons, New Orleans, LA, Jan 29–31, 2001.
https://doi.org/10.1016/S0003-4975(01)02787-4Get rights and content

Abstract

Background. It has previously been demonstrated that 17-allylamino geldanamycin (17-AAG) enhances paclitaxel-mediated cytotoxicity and downregulates vascular endothelial factor expression in non-small cell lung cancer. This project was designed to evaluate the tumoricidal and antiangiogeneic effects of 17-AAG and paclitaxel in H358 non-small cell lung cancer cells grown as xenografts in nude mice.

Methods. In vitro cytotoxic drug combination effects were evaluated by (4, 5-dimethylthiazo-2-yl)-2, 5-diphenyl tetrazolium bromide-based proliferation assays. The combinations of 17-AAG and paclitaxel were administered intraperitoneally in nude mice bearing H358 tumor xenografts. Tumor volumes were measured weekly. Tumor expression of erbB2, vascular endothelial cell growth factor, von Willebrand factor (tumor microvasculature), and activated caspase 3 (apoptosis) were determined by immunohistochemistry.

Results. Five- to 22-fold enhancement of paclitaxel cytotoxicity was achieved by paclitaxel + 17-AAG combination that was paralleled with marked induction of apoptosis. This combination treatment profoundly suppressed tumor growth and significantly prolonged survival of mice bearing H358 xenografts. Immunohistochemical staining of tumor tissues indicated profound reduction of vascular endothelial cell growth factor expression associated with reduction of microvasculature in tumors treated with 17-AAG. Apoptotic cells were more abundant in tumors treated with 17-AAG + paclitaxel than in those treated with 17-AAG or paclitaxel alone.

Conclusions. Concurrent exposure of H358 cells to 17-AAG and paclitaxel resulted in supraadditive growth inhibition effects in vitro and in vivo. Analysis of molecular markers of tumor tissues indicated that therapeutic drug levels could be achieved with this chemotherapy regimen leading to significant biological responses. Moreover, 17-AAG-mediated suppression of vascular endothelial cell growth factor production by tumor cells may contribute to the antitumor effects of this drug combination in vivo.

Section snippets

Cells and reagents

The NSCLC cell line H358 was purchased from American Tissue Culture Collection (Manassas, VA). Cells were maintained in RPMI media supplemented with glutamine (1 mmol/L), streptomycin (100 μg/mL)/penicillin (100 U/mL), and 10% of fetal calf serum. Normal human bronchial epithelial cells were purchased from Clonetics Corp (Walkersville, MD) and maintained in bronchial epithelial cell basal media (Clonetics Corp). The 17-AAG, obtained from the Drug Synthesis & Chemistry Branch, Developmental

Depletion of erbB1 and erbB2 expression on H358 cells by 17-AAG

The H358 cells expressed high levels of erbB2 (approximately threefold higher than the level detected on normal human bronchial epithelial cells), with mean fluorescence intensity of 160 ± 11. Exposure of H358 cells to 20 or 80 nmol/L of 17-AAG for 24 hours resulted in a dose-dependent reduction of erbB2 mean fluorescence intensity to 80 ± 6 and 40 ± 8 (p < 0.01 versus baseline controls, n = 3) (Fig 1). Moreover, at the higher dose of 17-AAG, erbB2 expression was completely depleted in 65% of

Comment

Previous studies have demonstrated that members of the erbB superfamily (particularly erbB1 and erbB2, which are frequently overexpressed in NSCLC cells) play important roles in mediating the response of tumor cells to cytotoxic stress and modulating their susceptibility to chemotherapeutic agents. Overexpression of erbB2 in cancer cells enhances resistance to various cytotoxic agents including cisplatin and paclitaxel as well as irradiation. Upregulation of DNA repair mechanisms mediated by

Acknowledgements

We acknowledge the superb technical assistance of Shawn Farid, BS, and Arnold Mixon, BS, of the Flow Cytometry Core Facility, Surgery Branch, National Cancer Institute, National Institutes of Health.

References (25)

  • T.W. Schulte et al.

    The benzoquinone ansamycin 17-allylamino-17-demethoxygeldanamycin binds to HSP90 and shares important biologic activities with geldanamycin

    Cancer Chemother Pharmacol

    (1998)
  • D.J. Slamon et al.

    Human breast cancercorrelation of relapse and survival with amplification of the HER-2/neu oncogene

    Science

    (1987)
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