Frequent cyclin D1 expression in chromate-induced lung cancers

Ex-chromate workers are frequently afflicted with lung cancers, especially central-type squamous cell carcinomas (SCCs) of the lung. However, little i s known about the molecular and cellular biologic characteristics of chroma te-induced lung cancers. We investigated expression of cyclin D1, bcl-2, an d p53 proteins in chromate-induced lung cancers by immunohistochemistry, co mpared with those in lung-cancers from nonexposed individuals and those in individuals with pneumoconiosis. Of 19 chromate-induced lung cancers, 16 tu mors were SCCs, including 11 central and 5 peripheral types. Eleven (69%) o f 16 chromate SCCs showed cyclin D1 expression. In contrast, cyclin D1 expr ession was observed in only 3 (12%) of 26 SCCs from nonexposed individuals and 6 (16%) of 37 SCCs that developed in patients with pneumoconiosis, resp ectively. The frequency of cyclin D1 expression proved to be significantly higher in chromate-induced SCCs than in SCCs from nonexposed individuals an d from those with pneumoconiosis (P < .001). When comparisons were extended to all histologic types of lung cancer, cyclin D1 expression was observed significantly more often in chromate-induced lung cancers than in lung canc ers from nonexposed subjects and those from patients with pneumoconiosis (1 1 [58%] of 19 v 5 [10%] of 52, P < .0011 and 7 [11%] of 63, P < .001, respe ctively). Frequencies of bcl-2 and p53 expression were not significantly di fferent among lung cancers from ex-chromate workers, nonexposed individuals and those with pneumoconiosis. The current study suggests that cyclin D1 e xpression may be involved in the development of chromate-induced lung cance rs, although its underlying mechanism remains to be determined. Copyright ( C) 2000 by W.B. Saunders Company.