Our previous studies identified UCA1 as a novel biomarker for bladder cancer and detected three variant transcripts of UCA1 in the human bladder TCC cell line BLZ-211 using northern blot analysis. One (1.4 kb) of the three transcripts has been shown to play a pivotal role in bladder cancer progression and embryonic development. In this study, we cloned a second transcript (2.2 kb), designated UCA1a, which was identical to previously reported cancer upregulated drug resistant gene (CUDR). Sequence comparison of UCA1 (1.4 kb transcript) and UCA1a(CUDR) cDNA revealed a 1,265 bp common region. Previous studies have demonstrated that CUDR is upregulated in various human tumors, including colon, cervical and lung cancer. However, the exact role of UCA1a(CUDR) in bladder cancer has not yet been reported. In this study, RT-PCR analysis indicated that UCA1a(CUDR) was also an embryonic development and bladder cancer-associated RNA. Overexpression of UCA1a(CUDR) significantly enhanced proliferation, migration and invasion of the bladder cancer cell line UM-UC-2. Moreover, microarray analysis demonstrated that overexpression of UCA1a(CUDR) was associated with signaling pathways regulating cell apoptosis and tumorigenesis. Furthermore, overexpression of UCA1a(CUDR) could antagonize cell apoptosis induced by cisplatin and promote the tumorigenicity of UM-UC-2 cells in vivo. Taken together, our data strongly suggest that similar to the 1.4 kb transcript of UCA1, UCA1a(CUDR) may also play an important role in the growth and tumorigenesis of human bladder cancer, and their common region may be critical for biological activity, thereby indicating that their common region may serve as a new therapeutic target for bladder cancer.