Immunohistochemistry for Histone H3 Lysine 9 Methyltransferase and Demethylase Proteins in Human Melanomas

Abstract

Methylation and demethylation of histone H3 lysine 9 (H3K9) play a role in the transcriptional regulation of several cancer-related genes and are closely associated with malignant tumor behavior. A novel study has recently demonstrated that SETDB1, a member of the H3K9 methyltransferases, accelerates tumor formation significantly in a zebrafish melanoma model. However, the expression of H3K9 methyltransferases including SETDB1 and demethylases has not been systematically examined in samples of human melanoma. Here, we used immunohistochemistry to examine the expression of the H3K9 methyltransferases, EHMT2 and SETDB1, and a H3K9 demethylase, LSD1, in 67 patients with melanoma. Overexpression of EHMT2, SETDB1, and LSD1 was observed in 14 (21%), 38 (57%), and 53 (79%) of the 67 patients, respectively. A significant relationship was observed between overexpression of EHMT2 or SETDB1 and aggressive tumor behavior such as lymph node metastasis and/or distant metastasis (P < 0.05), whereas no significant relationship was evident for LSD1 immunoreactivity. Univariate log-rank tests demonstrated that patients with melanoma overexpressing EHMT2 had a poorer outcome (P < 0.001), whereas overexpression of SETDB1 or LSD1 had no prognostic impact. These results suggest that overexpression of EHMT2 might be a prognostic marker in patients with melanoma.

Histone methyltransferase SETDB1 contributes to melanoma tumorigenesis and serves as a new potential therapeutic target

“…Several studies in the last decade indicated the involvement of SETDB1 expression in the progression of cancers such as lung carcinoma, glioma and hepatocellular carcinoma . In melanoma, SETDB1 is highly expressed in human samples in correlation with another histone methyltransferase, EHMT2 . Kostaki et al .…”

“…[24][25][26] In melanoma, SETDB1 is highly expressed in human samples in correlation with another histone methyltransferase, EHMT2. 27 Kostaki et al evaluated SETDB1 expression in tissue biopsies . This heatmap highlights all the genes that show a significant change in gene expression (after normalization, Student's t-test, log2-fold change >1 or <−1, FDR <0.05).…”

Genetics and epigenetics of melanoma

“…Transcriptional silencing by aberrant promoter methylation is associated with dimethylated lysine 9 in histone H3 (me2H3K9), resulting from the activity of H3K9 histone methyltransferases such as SETDB1 and EHMT2, and counteracted by H3K9 histone demethylase LSD1 (20). Transcriptional repression is believed to require binding of methyl-CpG binding protein (MECP2) and methyl-CpG binding domain protein 1 and 2 (MBD1 and MBD2) activity.…”

Histone profiles in cancer

“…Activity of this complex results in aberrant H3K9 methylation and cooperates with BRAFV600E in a zebrafish model. SETDB1 immunohistochemistry correlated with clinical characteristics in one study (Kostaki et al, 2014), while a study with a similar approach identified prognostic significance for G9A (EHMT2), but not SETDB1 expression (Miura et al, 2014). A functional role for SETBP1 and SUV39 has also been proposed in glioma and prostate cancer (Spyropoulou et al, 2014;Sun et al, 2014).…”