Background: Bladder cancer (BCa) is one of the most common urological malignancies. While Inositol-3-phosphate synthase 1 (ISYNA1) expression and function were largely unknown in BCa. We aimed to study the expression and role of ISYNA1 in bladder cancer and investigate its potential mechanisms via ingenuity pathway analysis (IPA). Methods: ISYNA1 expression was quantified by qRT-PCR in bladder cancer cell lines as well as normal urothelial cell line. Knocking down ISYNA1 gene in BCa T24 cells was achieved by shRNA lentivirus transfection. MTT and Celigo assay were used to assess cell proliferation. Flow cytometry was applied to test cell cycle and apoptosis. In addition, IPA was performed using PrimeView (TM) Human Gene Expression Array. Imunohistochemistry (IHC) was performed in BCa patient tissue microarray to verify the association between ISYNA1 expression and patients' clinicopathological features. Results: ISYNA1 was significantly upregulated in BCa samples vs. para-tumor tissues. Higher expression were significantly associated with tumor T stage and lymph node metastasis of bladder cancer patients. Similarly, it was elevated in BCa cell lines (5637 and T24) compared with SVHUC cells. Knocking down ISYNA1 significantly decreased proliferation, induced apoptosis and cell cycle arrest in T24 cells. Furthermore, IPA indicated that ISYNA1 was an important regulatory factors and related networks were involved in multiple functional processes. Conclusion: Taken together, current study suggest ISYNA1 promotes proliferation and inhibit apoptosis in bladder cancer cells, and its expression correlated with BCa patients' clinicopathological features. Thus, ISYNA1 may serve as a potential biomarker and therapeutic target for BCa patients. (C) 2019 Elsevier Inc. All rights reserved.