Methylation-associated inactivation of LATS1 and its effect on demethylation or overexpression on YAP and cell biological function in human renal cell carcinoma

Abstract

Large tumor suppressor 1 (LATS1) gene is one of the key factors in Hippo signaling pathway. Inactivation of LATS1 by promoter methylation was found in colorectal cancer (CRC), head and neck squamous cell carcinoma (HNSCC), astrocytoma, breast cancer and it was proved to be a tumor suppressor. However, its role is unclear in renal cell carcinoma (RCC). In this study, the expression of LATS1 was determined by reverse transcription polymerase chain reaction (RT‑PCR) and immunohistochemistry in 30 pairs of RCC tissues and matched normal kidney tissues and RCC cells. We found that the expression of LATS1 was markedly reduced in RCC tissues and cells, in the RCC tissue in 46.7% (14/30), while in the normal kidney tissues in 76.7% (23/30), and was associated with pathological grade and clinical stage of RCC. We detected methylation status of LATS1 by bisulfite sequence-PCR (BSP) in renal cancer cell line 786-O which lowers expression of LATS1, and we found it hypermethy-lated (in 97.5%). In addition, pharmacological demethylation using 5-Aza-2'-deoxycytidine (5-Aza) restored the expression of LATS1 mRNA and protein in 786-O cells, both LATS1 demethylation and overexpression of LATS1 downregulated the expression of Yes-associated protein (YAP), inhibited cell proliferation, induced cell apoptosis and cell cycle G1 arrest in 786-O cells. Thus, this report for the first time demonstrates the inactivation of LATS1 by promoter methy-lation and it is a tumor suppressor in kidney cancer. LATS1 may serve as a biomarker for possible early diagnosis and as a potential therapeutic target for human RCC.

Overexpression of the YAP1 oncogene in clear cell renal cell carcinoma is associated with poor outcome

“…The results of our study indicate that the decreased expression of LATS1 and increased YAP1 either at the mRNA or protein levels are highly associated with renal cancer progression. Our data corroborate the findings of Chen et al (39) in an RCC cell line (786-O) as well as in tissue samples. In paired tumor and normal kidney samples of 30 ccRCC patients they observed decreased LATS1 mRNA and protein levels in tumor samples; ccRCC progression was associated with lower LATS1 content (39).…”

“…Our data corroborate the findings of Chen et al (39) in an RCC cell line (786-O) as well as in tissue samples. In paired tumor and normal kidney samples of 30 ccRCC patients they observed decreased LATS1 mRNA and protein levels in tumor samples; ccRCC progression was associated with lower LATS1 content (39). Our data obtained on a much larger group of ccRCC patients extend these observations suggestive of the roles of LATS1 and YAP1 in ccRCC development since we found that the patients with deregulated LATS1 or YAP1 mRNA and protein levels share poorer clinical outcome.…”

“…Our data obtained on a much larger group of ccRCC patients extend these observations suggestive of the roles of LATS1 and YAP1 in ccRCC development since we found that the patients with deregulated LATS1 or YAP1 mRNA and protein levels share poorer clinical outcome. Thus, our and Chen et al (39) findings suggest that measurements of YAP1 mRNA content in ccRCC tumor samples could serve as a potential survival marker together with high Fuhrman's grades. In contrast to a previous study (37) we used quantitative techniques (qPCR vs. RT-PCR and MS-HRM-qPCR vs. bisulfide sequencing PCR) to assess a much larger group of ccRCC patients (86 vs. 30).…”

“…Chen et al also found that the controlled decrease in LATS1 protein level resulted in an increased YAP1 protein level. Furthermore, they observed that overexpression of LATS1 downregulated the YAP1 protein level, inhibited cell proliferation, induced cell apoptosis and cell cycle arrest in 786-O cells (39). LATS1 downregulation and its contribution to cancer progression has been observed in other malignances such as glioma (40), nosopharyngeal carcinoma (41), astrocytoma (42), non-small cell lung cancer (18), breast cancer (16), colorectal cancer (17) and renal carcinoma (39).…”

“…Furthermore, they observed that overexpression of LATS1 downregulated the YAP1 protein level, inhibited cell proliferation, induced cell apoptosis and cell cycle arrest in 786-O cells (39). LATS1 downregulation and its contribution to cancer progression has been observed in other malignances such as glioma (40), nosopharyngeal carcinoma (41), astrocytoma (42), non-small cell lung cancer (18), breast cancer (16), colorectal cancer (17) and renal carcinoma (39). Additionally, association between LATS1 hypermethylation and tumor progression has been noted in lung cancer (43), schwannomas (44), oral squamous cell carcinoma (45), colorectal cancer (17) and astrocytoma (42), however, the authors did not observe the influence of LATS1 methylation status on patient outcome.…”