Detection of mucin 7 gene expression in exfoliated cells in urine from patients with bladder tumor

Objectives. To determine whether mucin (MUC) 7 gene expression can be used as a bladder tumor marker for transitional cell carcinoma in patients with bladder carcinoma. Methods. Cells from the urine of 65 patients with bladder cancer, 15 patients with a negative bladder biopsy for bladder cancer, and 30 healthy volunteers were compared for the following parameters: tumor stage, grade, size, and number, urinary cytology, and expression of MUC7. Nested reverse transcriptase-polymerase chain reaction (RT-PCR) was used to determine MUC7 expression (348 base pairs). Results. MUC7 in the urine samples of the control group was negative (no false-positive results, specificity 100%). Among the 15 patients with nonmalignant disease, MUC7 was negative in 13 (specificity 87%). In the 2 patients with positive MUC7, the histologic examination showed chronic inflammation. Among the 65 patients with bladder transitional cell carcinoma, MUC7 was positive in 44 (68%). Nested RT-PCR for MUC7 was positive in 25 (61%) of 41 with superficial stages (pTa and pT1) versus 16 (76%) of 21 patients with Stage pT2 or advanced stages. Nested RT-PCR for MUC7 was positive in 5 (42%) of 12 patients with grade 1 disease, 22 (65%) of 34 patients with grade 2 disease, and 17 (89%) of 19 patients with grade 3 disease. We demonstrated no correlation between MUC7 and the clinicopathologic features (tumor stage, grade, or size) of urinary bladder tumors. Conclusions. Our results indicate that MUC7 is a potential marker for bladder cancer. This noninvasive detection method assesses urothelial cells from voided urine specimens using RT-PCR.