[Signal transducer and activator of transcription-3 inhibitor WP1066 affects human tongue squamous cell carcinoma proliferation and apoptosis in vitro and in vivo].

OBJECTIVE

To investigate the antitumour molecular mechanisms of WP1066 (STAT-3 inhibitor ) to human tongue squamous cell carcinoma in vitro and in vivo.

METHODS

WP1066 was used to inhibit the p-STAT-3 expression in Tscca human tongue squamous cell carcinoma cell line .Real-time PCR was used to detect the microRNA-21 expression after treatment with DMSO and WP1066. Methyl thiazolyl tatrozolium (MTT) assay was employed to determine cell survival. Flow cytometry (FCM) was used to measure apoptosis. The expression level of STAT-3/p-STAT-3, programmed cell death protein 4 (PDCD-4), antigen 67 (Ki-67), B cell lymphoma 2 (Bcl-2) and cleaved cysteinyl aspartate specific proteinase-3 (CCASP-3) was examined by Western blotting. Luciferase reporter gene assay was conducted to verify the regulation of STAT-3 to microRNA-21. Tscca xenograft tumor model was established in BALB/c nude mice and the tumors were divided into control, DMSO and WP1066 treated groups. The tumor tissues were measured by immunohistochemistry stain and terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) assay.

RESULTS

STAT-3/p-STAT-3 protein was suppressed after treatment with WP1066 (STAT-3:F = 15.336, P = 0.004, p-STAT-3: F = 52.837, P = 0.000). MicroRNA-21 relative expression level was down-regulated (F = 8.197, P = 0.019). Cell survival rate was significantly reduced after treatment with WP1066 than control groups (F = 94.388, P = 0.000). Early apoptosis rate increased after treatment with WP1066 (F = 217.080, P = 0.000) . PDCD-4 and cleaved cysteinyl aspartate specific proteinase-3 (CCASP-3) protein expression was increased after treatment with WP1066 (PDCD-4:F = 8.771, P = 0.017; CCASP-3: F = 26.611, P = 0.001) .Ki-67 and Bcl-2 protein was down regulated (Ki-67:F = 5.854, P = 0.039; Bcl-2:F = 125.502, P = 0.000). Luciferase reporter gene assay proved that STAT-3 combined with specific promoter region of microRNA-21.In vivo, the tumor volume after treatment with WP1066 was significantly smaller than control groups by the end of observation (F = 15.390, P = 0.000) .Immunological histological chemistry indicated that PDCD-4 and CCASP-3 protein expression was up-regulated simultaneously while Ki-67 and Bcl-2 protein of tumor tissue was down-regulated after treatment with WP1066 than control groups. TUNEL assay suggested that apoptosis index rose after treatment with WP1066 than control groups (F = 133.368, P = 0.000) .

CONCLUSIONS

WP1066 affected Tscca cancer cell proliferation and apoptosis via inhibiting STAT-3/microRNA-21.WP1066 provided new direction and possibility to human tongue squamous cell carcinoma therapy.