Objective      To investigate whether gemcitabine (GEM) will activate autophagy when GEM induced apoptosis in human bladder cancer T24 cells

and explore the underlying mechanism and the relationship between autophagy and apoptosis induced by GEM. Methods      Cell counting kit-8 (CCK-8) assay was used to detect the growth inhibition in human bladder cancer T24 cells after GEM treatment. Western blotting was used to detect the apoptosis related proteins Caspase-3 and PARP

autophagy marker proteins LC3-Ⅱ

P62 and autophagy flux

and JNK signaling pathway related proteins Jnk1

PJnk and Bcl-2. Transmission electron microscopy (TEM) was employed to observe the intracellular autophagosome. Flow cytometry (FCM) was used to measure cell apoptosis with aid of Annexin V-FITC apoptosis detection kit after inhibition of autophagy. Results      CCK-8 assay revealed that GEM effectively inhibited the proliferation of T24 cells. GEM treatment of 1.0 μg/mL resulted in obvious autophagy in the cells

and TEM displayed the formation of intracellular autophagosome. The results Western blotting showed the expression levels of cleaved-Caspase-3

PARP and LC3-Ⅱ were elevated

while that of p62 was reduced after GEM treatment. GEM also phosphorylated JNK and suppressed Bcl-2 to activate JNK signaling pathway. Inhibition of autophagy could enhance cell apoptosis in T24 cells after GEM treatment. Conclusion      GEM induces cell apoptosis in T24 cells

and also induces autophagy to protect the cells against apoptosis at the same time. JNK signaling pathway is involved in the regulation of autophagy

and inhibition of autophagy will significantly enhance the chemosensitivity of T24 cells to GEM.