Anti-HER2-antibody enhances irradiation-induced growth inhibition in head and neck carcinoma

To explore the antiproliferative effects of rhumAbHER2 on head and neck squ amous carcinoma cell (HNSCC) lines and breast cancer cell lines (BCCLs) and to evaluate the combined effects with irradiation, 2 human HNSCC lines and 2 BCCLs were exposed to rhumAbHER2 with or without irradiation. The result s showed that combined treatment enhanced the growth and colonization inhib itory effects of rhumAbHER2 or irradiation. Interestingly, the apoptotic ce ll fraction produced by irradiation disappeared on combined treatment. This disappearance was associated with repression of p53 and Bax upregulation i nduced by irradiation, but conservation of the upregulation of p27. Based o n these results, rhumAbHER2 and irradiation may be a new strategy for treat ing HNSCC and breast cancers. In addition, the upregulation of cyclin-depen dent kinase inhibitors by rhumAbHER2 may occur upstream of irradiation-indu ced p53 upregulation. (C) 2001 Wiley-Liss, Inc.