Deletions of p15 and p16 in schistosomal bladder cancer correlate with transforming growth factor-alpha expression.
OBJECTIVE
Cell proliferation is stimulated by growth factors and inhibited by p15 and p16 gene products. We compared cell regulators, TGF-alpha, p15, and p16, in schistosomal and non-schistosomal bladder cancer to explore possible differences in their alterations between the two subtypes and their correlations with proliferation pattern [synthetic phase fraction (SPF)], DNA ploidy, and clinicopathological factors.


METHODS
Tumor tissue samples were obtained from 120 patients. Expressions of p15 and p16 genes were investigated by the polymerase chain reaction, while TGF-alpha protein expression was measured by an enzyme immunoassay (EIA) method.


RESULTS
Deletion of both p15 and p16 was observed in 62 and 46 bladder tumors, respectively. TGF-alpha was overexpressed in 64 bladder tumors. A highly significant association was observed between the two deleted genes and TGF-alpha positivity. Of the entire group, p15 and p16 alteration and positive TGF-alpha (> or =cutoff value) were significantly expressed in schistosomal bladder cancer (68.1%, 60.9%, and 65.2%), and squamous cell carcinoma type (SCC) (69.1%, 64.7% and 72.1%) compared to those with non-schistosomal bladder cancer (29.4%, 7.8%, and 37.3%) or transitional cell carcinoma (TCC) (28.8%, 3.8%, and 28.8), respectively. A significant association between p15 and p16 deletion and TGF-alpha positivity with high SPF, aneuploid DNA pattern, late stages, and high histological grades was also documented.


CONCLUSIONS
Alteration of p15 and p16 genes and overexpression of TGF-alpha appears to be an event in bladder cancer that occurs more frequently in schistosomal bladder cancer and SCC, and may play an important role in their development. These observations may provide insight into treatment guided by molecular changes.
Swellam
Menha
M
Biochemistry Department, Genetic Engineering and Biotechnology Division, National Research Center, Cairo, Egypt. menha_m_swellam@hotmail.com
El-Aal
Abdullah Ahmed Abd
AA
AbuGabel
Khadiga M
KM
D002295:Carcinoma, Transitional Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D015972:Gene Expression Regulation, Neoplastic; D016147:Genes, Tumor Suppressor; D006801:Humans; D007124:Immunoenzyme Techniques; D011003:Ploidies; D012372:ROC Curve; D016211:Transforming Growth Factor alpha / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D001749:Urinary Bladder Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology
C493966:CDKN2B protein, human; D018797:Cell Cycle Proteins; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D017931:DNA Primers; D016211:Transforming Growth Factor alpha; D025521:Tumor Suppressor Proteins