hNaa10p contributes to tumorigenesis by facilitating DNMT1-mediated tumor suppressor gene silencing
Chung-Fan Lee, … , Cheng-Wen Wu, Li-Jung Juan
Chung-Fan Lee, … , Cheng-Wen Wu, Li-Jung Juan
Published July 1, 2010
Citation Information: J Clin Invest. 2010;120(8):2920-2930. https://doi.org/10.1172/JCI42275.
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Research Article Oncology

hNaa10p contributes to tumorigenesis by facilitating DNMT1-mediated tumor suppressor gene silencing

Abstract

Hypermethylation-mediated tumor suppressor gene silencing plays a crucial role in tumorigenesis. Understanding its underlying mechanism is essential for cancer treatment. Previous studies on human N-α-acetyltransferase 10, NatA catalytic subunit (hNaa10p; also known as human arrest-defective 1 [hARD1]), have generated conflicting results with regard to its role in tumorigenesis. Here we provide multiple lines of evidence indicating that it is oncogenic. We have shown that hNaa10p overexpression correlated with poor survival of human lung cancer patients. In vitro, enforced expression of hNaa10p was sufficient to cause cellular transformation, and siRNA-mediated depletion of hNaa10p impaired cancer cell proliferation in colony assays and xenograft studies. The oncogenic potential of hNaa10p depended on its interaction with DNA methyltransferase 1 (DNMT1). Mechanistically, hNaa10p positively regulated DNMT1 enzymatic activity by facilitating its binding to DNA in vitro and its recruitment to promoters of tumor suppressor genes, such as E-cadherin, in vivo. Consistent with this, interaction between hNaa10p and DNMT1 was required for E-cadherin silencing through promoter CpG methylation, and E-cadherin repression contributed to the oncogenic effects of hNaa10p. Together, our data not only establish hNaa10p as an oncoprotein, but also reveal that it contributes to oncogenesis through modulation of DNMT1 function.

Authors

Chung-Fan Lee, Derick S.-C. Ou, Sung-Bau Lee, Liang-Hao Chang, Ruo-Kai Lin, Ying-Shiuan Li, Anup K. Upadhyay, Xiaodong Cheng, Yi-Ching Wang, Han-Shui Hsu, Michael Hsiao, Cheng-Wen Wu, Li-Jung Juan

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Figure 5

hNaa10p maintains and stimulates DNMT1 activity by increasing DNMT1 binding to DNA.

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hNaa10p maintains and stimulates DNMT1 activity by increasing DNMT1 bind...
(A) H1299 cells transfected with si-hNAA10-1 or si-DNMT1 or treated with 5'-AzadC had reduced DNMT activity compared with cells mock transfected or transfected with si-Tax. Western blot shows expression of corresponding proteins. (B) Overexpressing WT hNaa10p, acetylase-dead mutant hNaa10p R82A, or DNMT1-V5 increased DNMT activity of 293T cells. (C) hNaa10p stimulated DNMT1 activity independently of acetyl-CoA. Recombinantly purified DNMT1 and His-hNaa10p, alone or in combination, were mixed with or without acetyl-CoA, followed by DNMT assay. (D) hNaa10p facilitated DNMT1 binding to DNA in vitro. EMSA assays were applied with the biotin-labeled hemimethylated DNA probe alone or with the recombinantly purified DNMT1 in the absence or presence of increasing amounts of E. coli–expressed and purified His-hNaa10p. (E) ChIP assay showed that enforced expression of vector or hNaa10p in H1299 cells enhanced DNMT1 binding to promoter of E-cadherin, but not p21. (F) ChIP showed that depleting hNaa10p from H1299 cells by si-hNAA10-2 abolished DNMT1 binding to the E-cadherin promoter, whereas DNMT1 loss of function did not impair hNaa10p binding to the same promoter. Lanes in A and B were run on the same gel but were noncontiguous (white lines).