Epidermal growth factor receptor family and chemosensitization

Alteration in the expression and activation of protein tyrosine kinases and cell cycle regulatory genes not only can lead directly to the perturbation of growth regulation but also may affect the sensitivity of cancer cells to conventional chemotherapy and radiation therapy. In recent years, numerous studies have ex-plored the effects on chemosensitivity resulting from altered expression and activation of the epidermal growth factor (EGF) receptor and the HER-2/neu receptor. In this issue of the Journal, Dixit et al. (1) report that reduced expression of EGF receptors achieved by introduction of EGF receptor antisense oligonucleotides is associated with increased resistance to cisplatin in MDA-468 human breast cancer cells, which express high levels of EGF receptors (>106/cell). This finding was attributed to abrogation of cisplatin-induced apop-tosis in the transfectants. Dixit et al. suggest that critical level