Formation of DNA interstrand cross-links as a marker of Mitomycin C bioreductive activation and chemosensitivity

Tumour response to Mitomycin C (MMC) is heterogenous and past attempts to predict clinical response based on enzyme activities have proven unsatisfactory. Using in vitro techniques, the aim of this study was to determine if the induction of DNA interstrand cross-links correlated with cellular response and to assess if DNA repair and induction of apoptosis influenced MMC chemosensitivity. Poor correlations were found between sensitivity and both DNA repair and induction of apoptosis suggesting that these processes do not play a major role in determining cellular response to MMC. In contrast, there was good correlation between the induction of DNA interstrand cross-links as determined by the alkaline comet assay and cellular response, suggesting that the biochemical events leading to DNA damage are the key factors that determine cellular response in vitro. Further studies are required to assess whether this approach as a mean of prediction has practical applications in vivo

Expression of matrix metalloproteinase-10 in human bladder transitional cell carcinoma

OBJECTIVES: To analyze matrix metalloproteinase-10 (MMP-10) expression in transitional cell carcinoma (TCC) of the bladder, evaluate the correlations between MMP-10 protein expression and clinicopathologic parameters, and address the viability of MMP-10 as a therapeutic target for TCC. MMP-mediated degradation of the extracellular matrix is an important factor in the pathogenesis of tumorigenesis and metastasis. METHODS: Using immunohistochemistry, the expression of MMP-10 was assessed using both tissue microarrays and whole sections of archival tissue specimens representative of all grades and stages of human bladder TCC (n = 60). MMP-10 expression was also assessed in histologically normal human bladder tissue (n = 10). The immunostaining results for MMP-10 expression were examined for correlations with tumor grade and stage. RESULTS: Unlike most MMPs, MMP-10 was localized primarily in the tumor mass as opposed to the tumor stroma and was detectable in all grades and stages of TCC. Significantly greater levels of MMP-10 protein were observed in superficial (pTa, pT1; n = 38) tumors than in normal bladder tissue (P = 0.01). In contrast to the proposed role of MMPs in tumor invasion, no significant difference was observed between muscle-invasive tumors (pT2 or worse; n = 22) and histologically normal bladder tissue (P = 0.50). MMP-10 expression showed no significant correlation with tumor grade. CONCLUSIONS: The data from our study showed that, unlike most MMPs, MMP-10 was not associated with tumor aggression or invasion. Our results suggest that MMP-10 protein levels are significantly greater in the earlier stages of TCC development

MMP-10 is overexpressed, proteolytically active and a potential target for therapeutic intervention in human lung carcinomas

Matrix metalloproteinase (MMP)-mediated degradation of the extracellular matrix is a major factor for tumor development and expansion. This study analysed MMP-10 protein expression and activity in human lung tumors of various grade, stage, and type to address the relationship between MMP-10 and tumor characteristics and to evaluate MMP-10 as a therapeutic target in non small cell lung carcinoma (NSCLC). Unlike the majority of MMPs, MMP-10 was located in the tumor mass as opposed to tumor stroma. MMP-10 protein was observed at low levels in normal human lung tissues and at significantly higher levels in all types of NSCLC. No correlation was observed between MMP-10 protein expression and tumor type, stage, or lymph node invasion. To discriminate between active and inactive forms of MMP-10 in samples of human NSCLC, we have developed an ex vivo fluorescent assay. Measurable MMP-10 activity was detected in 42 of 50 specimens of lung cancer and only 2 of 10 specimens of histologically normal lung tissue. No relationship was observed between MMP-10 activity levels and clinicopathologic characteristics. Our results suggest that MMP-10 is expressed and active at high levels in human NSCLC compared to normal lung tissues, and, as such, is a potential target for the development of novel therapeutics for lung cancer treatment

NAD(P)H : quinone oxidoreductase-1 C609T polymorphism analysis in human superficial bladder cancers : relationship of genotype status to NQO1 phenotype and clinical response to Mitomycin C.

NAD(P)H:Quinone oxidoreductase-1 (NQO1) has been implicated in the bioreductive activation of the clinically active anticancer drug Mitomycin C (MMC) and a polymorphic variant of NQO1 which lacks functional enzyme activity (NQO1*2) has been linked with poor survival in patients treated with MMC. The relationship between NQO1 activity and cellular response to MMC is however controversial and the aim of this study was to determine whether the response of bladder cancer patients to MMC can be forecast on the basis of NQO1*2 genotype status. Genomic DNA was extracted from formalin-fixed, paraffin-embedded tissue from 148 patients with low to intermediate grade (G1/G2) superficial (Ta/T1) bladder cancers and NQO1*2 genotype status determined by PCR-RFLP. NQO1*2 genotype status was retrospectively compared with clinical response to intravesical administered MMC with the primary end-point being time to first recurrence. NQO1 phenotype was determined by immunohistochemistry. Of the 148 patients genotyped, 85 (57.4%) were NQO1*1 (wild-type), 59 (39.8%) were NQO1*1/*2 (heterozygotes) and 4 (2.7%) were NQO1*2/*2. No NQO1 protein expression was detected in NQO1*2/*2 tumours. A broad spectrum of NQO1 protein expression existed in tumours genotyped as NQO1*1 and NQO1*1/*2 although tumours with NQO1*1 typically expressed higher NQO1 protein. A poor correlation existed between NQO1*2 genotype status and clinical response to MMC. The results of this retrospective study suggest that tailoring MMC therapy to individual patients with superficial bladder cancer on the basis of NQO1 genotype status is unlikely to be of clinical benefit