Objective      To investigate the effects of large tumor suppressor gene 1 (LATS1) demethylation on the biological function and Hippo-YAP signaling pathway in human renal cell carcinoma (RCC) cells.       Methods      T

he mRNA expression levels of LATS1 and downstream gene YAP of Hippo-YAP signaling pathway were detected by RT-PCR in human clear cell RCC cell line 786-O and human embryonic kidney cell line HEK-293. The methylation of 786-O cells with low LATS1 expression was analyzed by bisulfite sequence-PCR (BSP). After 786-O and HEK-293 cells were treated by 5-aza-2′-deoxycytidine (DAC)

the  mRNA and protein levels of LATS1 and YAP were detected by RT-PCR and Western blotting in each group. Cell apoptosis and cell cycle were detected by flow cytometry (FCM). The cell proliferation inhibition was detected by cell proliferation and toxicity detection reagent (CCK-8).       Results      Compared with the HEK-293 cells

the mRNA expression level of LATS1  was significantly decreased (

P

0.05)

while that of YAP was markedly increased (

P

0.05) in the 786-O cells. LATS1 was highly methylated in the 786-O cells as proven by BSP. After DAC treatment in the 786-O cells

the mRNA and protein expression levels of LATS1 were dramatically increased (

P

0.05)

but those of YAP were significantly decreased (

P

0.05). Cell cycle was arrested in G

0

/G

1

phase (

P

0.05) and cell proliferation was obviously inhibited (

P

0.05). Cell apoptosis was increased significantly (

P

0.05). In the HEK-293 cells

however

those above-mentioned changes were insignificant (

P

0.05).       Conclusion      The demethylation of LATS1 gene down-regulates the expression of YAP gene

inhibits the cell proliferation of 786-O cells and induces apoptosis. The methylation of LATS1 gene may contribute greatly to the occurrence of RCC.