Chromosomal gains of 1q21-q22 and 13q12-q14 were closely related with the chemoresistance of patients with ovarian cancer in our previous CGH (comparative genomic hybridization) study. We conducted the present study to determine the amplified genes on chromosome 1q. Comparisons of relative copy numbers of clinically platinum-sensitive ovarian tumors (CR-group, n=14) and platinum-resistant tumors (PD-group, n=14) were carried out using real-time PCR from ten different gene loci on chromosome 1q. Increased copy numbers were frequently observed in PD-group tumors, especially in the region between WI-8123 and MUC1. Relative copy number of MUC1 over 1.5 was observed in 13 (92%) of 14 PD-group tumors and 3 (21%) of 14 CR-group tumors (p<0.05). Moreover, cytoplasmic expressions of MUC1 protein were significantly higher in PD-group than those in CR-group (p<0.01). We concluded that the cytoplasmic overexpression of MUC1 might be an indicator of resistance to platinum-based chemotherapy and a prognostic marker in ovarian cancer.

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