Impact of histone methyltransferase SUV420H2 in breast cancer

Breast cancer is the most common type of cancer in women worldwide. Triple methylation of H4 lysine 20 (H4K20me3), a key component of epigenetic regulation of genomic integrity, is catalyzed by the methyltransferase, SUV420H2. Data on the expression status of SUV420H2 in breast cancer are limited. In the present study, the influence of SUV420H2 suppression on the proliferation of breast cancer cells was experimentally investigated. Subsequently, SUV420H2 expression was assessed in resectable breast cancer along with H4K20me3 status. SUV420H2 expression was knocked down in breast cells using small interfering RNA oligonucleotides. SUV420H2 expression was determined semi-quantitatively at the mRNA level. H4K20me3 was measured on extracted histone proteins using an approach similar to ELISA. Suppression of the SUV420H2 gene resulted in increased cell proliferation. Although the median SUV420H2 expression values were similar in tumor tissues and non-cancerous regions in the entire cohort (0.0022 and 0.0015, respectively; P=0.46), there was a notable difference in expression between tumor tissues and the adjacent non-cancerous region in the majority of patients. Increased SUV420H2 expression in tumors compared with healthy tissue was predominantly observed in patients with early-stage breast cancer, whereas reduced SUV420H2 expression was observed in tumors more frequently in patients with advanced stage diseases. There was no association between SUV420H2 expression and the tissue levels of H4K20me3. The results showed that SUV420H2 exhibited anti-proliferative activity in vitro, and exhibits a heterogeneous expression pattern in breast cancer tissues.