Alteration of p16(INK4a) and cyclin D1 in head and neck carcinoma cell lines

p16(INK4a) and cyclin D1 genes cooperatively regulate cyclin-dependent kina se 4 mediated phosphorylation of PRE in the cell cycle of normal cells. We have determined somatic alterations in p16(INK4a) and cyclin D1 in nine cel l lines of squamous cell carcinoma of the head and neck (SCCHN). p16(INK4a) protein was not detected in seven of the cell lines. These cases contained a homozygous deletion (four cases) in the exon 1 region of p16(INK4a) and mutation tone case) in exon 2. Cyclin D1 gene amplification and expressions of mRNA and protein seemed to be of normal status in seven cell lines. Sup pression of cyclin D1 mRNA expression was observed in two cell lines. In si x of the nine lines, p16(INK4a) showed low p16(INK4a) protein or its total absence, while cyclin D1 was intact. Therefore the balance of G1 cyclin (cy clin D1) and its inhibition (p16(INK4a)) is thought to be important for tum ourigenesis and tumour progression in SCCHN. Med Sci Res 27:479-484 (C) 199 9 Lippincott Williams & Wilkins.