Objective methods for diagnosing a predisposition to developing cancer, particularly bladder cancer, gastric cancer, colorectal cancer, breast cancer, esophageal cancer, lung cancer, lymphoma, pancreatic cancer and testicular cancer, are described herein. In one embodiment, the diagnostic method involves determining an expression level of PRMT1 gene. The present invention further provides methods of screening for therapeutic agents useful in the treatment of PRMT1 associated disease, such as a cancer, e.g. bladder cancer, gastric cancer, colorectal cancer, breast cancer, esophageal cancer, lung cancer, lymphoma, pancreatic cancer and testicular cancer. The present invention further provides methods of inhibiting the cell growth and treating or alleviating symptoms of PRMT1 associated diseases. The present invention also features products, including double-stranded molecules and vectors encoding thereof as well as to compositions comprising them.