Clinical relevance of maspin expression in bladder cancer

Transitional cell carcinoma (TCC) of the bladder is a solid tumor that induces angiogenesis to maintain nutrition and oxygenation of tumor cells. Maspin, a serpin with tumor suppressing activity, has recently been identified as an inhibitor of angiogenesis. This study examined the impact of maspin expression in the growth pattern of TCC of the bladder. Maspin was identified in a panel of normal tissues, in several bladder carcinoma cell lines, and 51 patient samples of TCC of the bladder. Expression was detected by RT-PCR and immunohistochemistry. Furthermore, the level of maspin was correlated to the growth rate of bladder tumor cell lines in vitro and in vivo. Maspin expression was found in high quantities in normal urothelium. Maspin expression was preserved in superficial bladder cancers but was significantly diminished in invasive carcinomas. Within the group of invasive TCCs, maspin expression was inversely correlated to the patient prognosis. Furthermore, low maspin expression level was coupled to an increased tumor cell growth in vivo. Down-regulation of maspin expression seems to be a specific event in the progression of invasive bladder carcinoma. Maspin might be a useful marker to determine the prognosis of invasive TCC. Furthermore, maspin re-expression might become a therapeutic option in the treatment of invasive, metastatic TCC.