The results of the present study demonstrated that knockdown of GAS5 expression promoted bladder cancer cell proliferation, whereas overexpression of GAS5 suppressed cell proliferation. Furthermore, knockdown of GAS5 resulted in an increased percentage of cells in S and G2 phase, and a decreased percentage of cells in G1 phase. Knockdown of GAS5 expression increased the mRNA and protein expression of CCL1 in bladder cancer cells. Gain-of-function and loss-of-function studies demonstrated that GAS5 was able to inhibit bladder cancer cell proliferation, at least in part, by suppressing the expression of CCL1.