FREQUENCY OF EXPRESSION OF PROSTATE-SPECIFIC ANTIGEN MESSENGER-RNA INLUNG-TUMORS

The presence of prostate-specific antigen (PSA) protein and messenger RNA (mRNA) was studied in 52 primary lung tumor tissues. The PSA prote in was detected more frequently and at higher levels in lung tumor ext racts from men. The levels of PSA protein in tumor extracts correlated with preoperative and postoperative serum PSA levels, suggesting a po ssible contamination of the tumor extracts with PSA from residual bloo d in the tumor vasculature. The PSA mRNA was detected by reverse trans cription-polymerase chain reaction (RT-PCR) and Southern blot hybridiz ation in 24 (68%) of 35 tumors from men, in 9 (53%) of 17 tumors from women, and in 5 (71%) of 7 adjacent normal lung tissue specimens. The levels of PSA protein did not associate with patient age, the tumor st age, grade, or histologic type, or the nodal status. Similarly, PSA mR NA was not associated with any clinicopathologic variables, but squamo us cell carcinomas, especially in men, were more frequently positive. A by-product of the RT-PCR procedure was cloned and sequenced and foun d to be a 450-base pair sequence not previously deposited in the data bank. We conclude that PSA mRNA and protein frequently can be detected in lung tumors and normal tissues from men and women but at levels mu ch lower than those seen in breast carcinomas in women. The significan ce of the new 450-base pair sequence remains to be determined.