Effects of a JAK inhibitor, AG490, on proliferation and apoptosis of human nasopharyngeal carcinoma cell line CNE-2Z.

BACKGROUND AND OBJECTIVE: Abnormal activation of Janus kinas/signal transducer and activator of transcription 3 (JAK-STAT3) signaling pathway is closely related to malignant transformation of cells. This study was to investigate the effects of a JAK inhibitor, AG490, on the proliferation, apoptosis, and expressions of apoptosis-related survivin and Mcl-1 genes, thus to explore the role of JAK-STAT3 signaling pathway in the regulation of cell apoptosis in nasopharyngeal carcinoma (NPC) cell line CNE-2Z.

METHODS: CNE-2Z cells were treated with different doses of AG490. The cell proliferation was measured using MTT array. Cell apoptosis was assessed by flow cytometry (FCM) and Hoechst33342 fluorescence staining. The mRNA levels of STAT3, survivin and Mcl-1 were detected by reverse transcription-polymerase chain reaction (RT-PCR). The protein contents of STAT3, phosphoralated STAT3 (p-STAT3), survivin and Mcl-1 were measured by western blot.

RESULTS: The inhibition rates of CNE-2Z cell proliferation by 100 micromol/L AG490 were 37.95% and 52.99% at 24 and 48 h after treatment. After incubation with 50 micromol/L and 100 micromol/L AG490 for 24 h, the apoptotic rates of CNE-2Z cells were increased from 1.37% to 9.30% and 9.00%, respectively (p < 0.01); typical changes in apoptotic morphology were observed under fluorescence microscopy; moreover, activation of STAT3 was inhibited, mRNA and protein levels of Mcl-1 and survivin were down-regulated.

CONCLUSION: Blocking of JAK-STAT3 signaling pathway in CNE-2Z cells could remarkably inhibit cell proliferation and inactivate STAT3, as well as promote cell apoptosis by down-regulating Mcl-1 and survivin.