尿路上皮癌の診断・治療への分子生物学的アプローチ

Abstract

Detection of urinary telomerase activity is superior to the conventional urine cytological examination in terms of sensitivity for diagnosis of low grade urothelial cancers. Several causative factors including pyuria and hematuria which might have affected falsely positive and negative rates of urinary telomerase activity were investigated but their influence seemed negligible. As for progression from superficial to invasive urothelial cancers, destruction of the basement membrane underlying tumor is considered as an important event in the initial step of invasion. Our immunohistochemical analyses revealed that expression of type IV collagen in the basement membrane was reduced or disappeared in more than half of grade 2 to 3, pTa urothelial cancers. Overexpression of p53 tumor suppressor and/or mdm2 oncoprotein was strongly correlated with this basement membrane destruction. Urothelial cancers harboring p53 aberration may be resistant to cisplatin-based chemotherapy because of impairment of apoptosis induction. The relationship between chemosensitivity and p53 status in urothelial cancers was investigated, and a favorable response to neoadjuvant chemotherapy was found in tumors without p53 aberration.