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Frequency of expression of prostate-specific antigen mRNA in lung tumors
N Zarghami1, M Levesque, M D'Costa
1Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada.
Abstract:
The presence of prostate-specific antigen (PSA) protein and messenger RNA (mRNA) was studied in 52 primary lung tumor tissues. The PSA protein was detected more frequently and at higher levels in lung tumor extracts from men. The levels of PSA protein in tumor extracts correlated with preoperative and postoperative serum PSA levels, suggesting a possible contamination of the tumor extracts with PSA from residual blood in the tumor vasculature. The PSA mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot hybridization 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 stage, grade, or histologic type, or the nodal status. Similarly, PSA mRNA was not associated with any clinicopathologic variables, but squamous cell carcinomas, especially in men, were more frequently positive. A by-product of the RT-PCR procedure was cloned and sequenced and found 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 much lower than those seen in breast carcinomas in women. The significance of the new 450-base pair sequence remains to be determined.
Insights
Prostate-specific antigen (PSA) protein and mRNA are frequently detected in lung tumors and normal tissues. However, levels are lower than in breast cancer, and their presence doesn't correlate with most clinicopathologic factors.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Prostate-specific antigen (PSA) is a well-established biomarker for prostate cancer.
- The presence and significance of PSA in non-prostate tissues, such as lung, are less understood.
Purpose of the Study:
- To investigate the presence and levels of PSA protein and mRNA in primary lung tumors.
- To explore potential correlations between PSA expression and clinicopathologic variables in lung cancer patients.
- To identify any novel genetic sequences associated with PSA detection in lung tissue.
Main Methods:
- Analysis of PSA protein and mRNA in 52 primary lung tumor tissues using Western blot and RT-PCR.
- Correlation analysis with patient age, tumor stage, grade, histology, and nodal status.
- Sequencing of a novel 450-base pair by-product from RT-PCR.
Main Results:
- PSA protein detected more frequently and at higher levels in male lung tumors, correlating with serum PSA.
- PSA mRNA detected in 68% of male tumors, 53% of female tumors, and 71% of normal lung tissues.
- No significant association found between PSA levels (protein or mRNA) and most clinicopathologic variables, though squamous cell carcinomas showed higher positivity.
Conclusions:
- PSA protein and mRNA are frequently detectable in lung tumors and normal lung tissues from both sexes.
- Detected levels are significantly lower than those observed in breast carcinomas.
- The clinical significance of PSA in lung tissue and the newly identified 450-bp sequence require further investigation.