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G9a is essential for EMT-mediated metastasis and maintenance of cancer stem cell-like characters in head and neck squamous cell carcinoma.

Liu S, Ye D, Guo W, Yu W, He Y, Hu J, Wang Y, Zhang L, Liao Y, Song H, Zhong S, Xu D, Yin H, Sun B, Wang X, Liu J, Wu Y, Zhou BP, Zhang Z, Deng J - Oncotarget (2015)

Bottom Line: We found that G9a, a histone methyltransferase, interacts with Snail and mediates Snail-induced transcriptional repression of E-cadherin and EMT, through methylation of histone H3 lysine-9 (H3K9).Moreover, G9a is required for both lymph node-related metastasis and TGF-β-induced EMT in HNSCC cells since knockdown of G9a reversed EMT, inhibited cell migration and tumorsphere formation, and suppressed the expression of CSC markers.Thus, targeting the G9a-Snail axis may represent a novel strategy for treatment of metastatic HNSCC.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral and Maxillofacial-Head and Neck Oncology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.

ABSTRACT
Head and neck squamous cell carcinoma (HNSCC) is a particularly aggressive cancer with poor prognosis, largely due to lymph node metastasis and local recurrence. Emerging evidence suggests that epithelial-to-mesenchymal transition (EMT) is important for cancer metastasis, and correlated with increased cancer stem cells (CSCs) characteristics. However, the mechanisms underlying metastasis to lymph nodes in HNSCC is poorly defined. In this study, we show that E-cadherin repression correlates with cancer metastasis and poor prognosis in HNSCC. We found that G9a, a histone methyltransferase, interacts with Snail and mediates Snail-induced transcriptional repression of E-cadherin and EMT, through methylation of histone H3 lysine-9 (H3K9). Moreover, G9a is required for both lymph node-related metastasis and TGF-β-induced EMT in HNSCC cells since knockdown of G9a reversed EMT, inhibited cell migration and tumorsphere formation, and suppressed the expression of CSC markers. Our study demonstrates that the G9a protein is essential for the induction of EMT and CSC-like properties in HNSCC. Thus, targeting the G9a-Snail axis may represent a novel strategy for treatment of metastatic HNSCC.

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Related in: MedlinePlus

Knockdown of G9a expression inhibits cell migration in HNSCC(A) Morphologic changes in stably transfected HN12 cells with knockdown of G9a and control HN12 cells by phase contrast microscopy. Immunofluorescence (IF) staining for E-cadherin, N-cadherin and vimentin is presented with nuclei stained with DAPI (blue). Scale bar = 200 μm. (B) Western blot analysis of E-cadherin, N-cadherin and vimentin in HN12 cells stably expressing control vector or G9a shRNA. (C) Migration of HN12 cells stably expressing control vector or G9a shRNA analyzed using the transwell migration assay. Scale bar = 200 μm. (D) Graph demonstrates the mean ± SD percent migrated cells in HN12 vector control and shG9a cells from 3 separate experiments.
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Figure 6: Knockdown of G9a expression inhibits cell migration in HNSCC(A) Morphologic changes in stably transfected HN12 cells with knockdown of G9a and control HN12 cells by phase contrast microscopy. Immunofluorescence (IF) staining for E-cadherin, N-cadherin and vimentin is presented with nuclei stained with DAPI (blue). Scale bar = 200 μm. (B) Western blot analysis of E-cadherin, N-cadherin and vimentin in HN12 cells stably expressing control vector or G9a shRNA. (C) Migration of HN12 cells stably expressing control vector or G9a shRNA analyzed using the transwell migration assay. Scale bar = 200 μm. (D) Graph demonstrates the mean ± SD percent migrated cells in HN12 vector control and shG9a cells from 3 separate experiments.

Mentions: To confirm this observation, we established stable shRNA-G9a transfectants of HN12 cells with knockdown of G9a expression. The knockdown efficiency of endogenous G9a by shRNA was about 80% (Figure 6B). Knockdown of G9a restored E-cadherin expression and dramatically downregulated N-cadherin and vimentin in HN12 cells (Figure 6A and 6B). In addition, knockdown of G9a greatly inhibited the motility and migration of HN12 cells (Figure 6C and 6D). Taken together, these results strongly support the assertion that G9a is essential for repression of E-cadherin, with subsequent EMT and metastasis to lymph nodes in HNSCC.


G9a is essential for EMT-mediated metastasis and maintenance of cancer stem cell-like characters in head and neck squamous cell carcinoma.

Liu S, Ye D, Guo W, Yu W, He Y, Hu J, Wang Y, Zhang L, Liao Y, Song H, Zhong S, Xu D, Yin H, Sun B, Wang X, Liu J, Wu Y, Zhou BP, Zhang Z, Deng J - Oncotarget (2015)

Knockdown of G9a expression inhibits cell migration in HNSCC(A) Morphologic changes in stably transfected HN12 cells with knockdown of G9a and control HN12 cells by phase contrast microscopy. Immunofluorescence (IF) staining for E-cadherin, N-cadherin and vimentin is presented with nuclei stained with DAPI (blue). Scale bar = 200 μm. (B) Western blot analysis of E-cadherin, N-cadherin and vimentin in HN12 cells stably expressing control vector or G9a shRNA. (C) Migration of HN12 cells stably expressing control vector or G9a shRNA analyzed using the transwell migration assay. Scale bar = 200 μm. (D) Graph demonstrates the mean ± SD percent migrated cells in HN12 vector control and shG9a cells from 3 separate experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4466657&req=5

Figure 6: Knockdown of G9a expression inhibits cell migration in HNSCC(A) Morphologic changes in stably transfected HN12 cells with knockdown of G9a and control HN12 cells by phase contrast microscopy. Immunofluorescence (IF) staining for E-cadherin, N-cadherin and vimentin is presented with nuclei stained with DAPI (blue). Scale bar = 200 μm. (B) Western blot analysis of E-cadherin, N-cadherin and vimentin in HN12 cells stably expressing control vector or G9a shRNA. (C) Migration of HN12 cells stably expressing control vector or G9a shRNA analyzed using the transwell migration assay. Scale bar = 200 μm. (D) Graph demonstrates the mean ± SD percent migrated cells in HN12 vector control and shG9a cells from 3 separate experiments.
Mentions: To confirm this observation, we established stable shRNA-G9a transfectants of HN12 cells with knockdown of G9a expression. The knockdown efficiency of endogenous G9a by shRNA was about 80% (Figure 6B). Knockdown of G9a restored E-cadherin expression and dramatically downregulated N-cadherin and vimentin in HN12 cells (Figure 6A and 6B). In addition, knockdown of G9a greatly inhibited the motility and migration of HN12 cells (Figure 6C and 6D). Taken together, these results strongly support the assertion that G9a is essential for repression of E-cadherin, with subsequent EMT and metastasis to lymph nodes in HNSCC.

Bottom Line: We found that G9a, a histone methyltransferase, interacts with Snail and mediates Snail-induced transcriptional repression of E-cadherin and EMT, through methylation of histone H3 lysine-9 (H3K9).Moreover, G9a is required for both lymph node-related metastasis and TGF-β-induced EMT in HNSCC cells since knockdown of G9a reversed EMT, inhibited cell migration and tumorsphere formation, and suppressed the expression of CSC markers.Thus, targeting the G9a-Snail axis may represent a novel strategy for treatment of metastatic HNSCC.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral and Maxillofacial-Head and Neck Oncology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.

ABSTRACT
Head and neck squamous cell carcinoma (HNSCC) is a particularly aggressive cancer with poor prognosis, largely due to lymph node metastasis and local recurrence. Emerging evidence suggests that epithelial-to-mesenchymal transition (EMT) is important for cancer metastasis, and correlated with increased cancer stem cells (CSCs) characteristics. However, the mechanisms underlying metastasis to lymph nodes in HNSCC is poorly defined. In this study, we show that E-cadherin repression correlates with cancer metastasis and poor prognosis in HNSCC. We found that G9a, a histone methyltransferase, interacts with Snail and mediates Snail-induced transcriptional repression of E-cadherin and EMT, through methylation of histone H3 lysine-9 (H3K9). Moreover, G9a is required for both lymph node-related metastasis and TGF-β-induced EMT in HNSCC cells since knockdown of G9a reversed EMT, inhibited cell migration and tumorsphere formation, and suppressed the expression of CSC markers. Our study demonstrates that the G9a protein is essential for the induction of EMT and CSC-like properties in HNSCC. Thus, targeting the G9a-Snail axis may represent a novel strategy for treatment of metastatic HNSCC.

Show MeSH
Related in: MedlinePlus