Effects of the Demethylating Agent, 5-Azacytidine, on Expression of the Kallikrein-Kinin Genes in Carcinoma Cells of the Lung and Pleura

Abstract

Tissue kallikrein (KLK1) and plasma kallikrein (KLKB1) may regulate the growth and proliferation of tumours of the lung and pleura, through the generation of kinin peptides that signal through the kinin B1 (BDKRB1) and B2 (BDKRB2) receptors. The development and progression of cancer results from genetic mutations, as well as epigenetic changes that include methylation of DNA at CpG islands. The aim of this study was to assess whether expression of the kallikrein-kinin genes in lung cancer and mesothelioma cells is regulated by DNA methylation. Quantitative reverse transcriptase-PCR and immunocytochemistry showed differences in the basal expression of the kallikrein-kinin genes and proteins in lung carcinoma and mesothelioma cells, compared with non-malignant lung epithelial and mesothelial cells, respectively. Following treatment with the demethylating agent, 5-azacytidine (5-AZA), KLKB1 mRNA expression was consistently increased in both lung carcinoma and mesothelioma cells, whereas KLK1, BDKRB1 and BDKRB2 mRNA expression was decreased or unchanged. Increased expression of KLKB1 after 5-AZA treatment suggests it may function as a tumour suppressor gene in cancers of the lung and pleura. Studies on DNA methylation of the kallikrein-kinin genes will enhance understanding of their role in carcinogenesis and provide insights into the importance of kallikreins as tumour biomarkers.

10 Kallikrein-Kinin Cascade: Bioregulation by Human Tissue Kallikrein 1 (hK1, KLK1)

“…10.4). The lack of suppression by 5-azacytidine of the KLK1 gene in cancer cells in the lung and pleura suggests that it probably is an oncogene (Wong et al, 2011). The lack of increase in the expression of KLK1 may be due to non-existent CpG motifs at critical sites in the promoter, or suppression of transcription factors in non-promoter regions, or remethylation by the RNAi machinery.…”

“…In lung cancer and malignant mesotheliomas KLK1 and KLKB1 are differentially expressed (Chee et al, 2007;. Therefore, in order to understand whether epigenetic changes are involved in the differential expression of KLK genes in the carcinomas of the lung and pleura, as a first step, the focus was on DNA-demethylation Wong et al, 2011) employing 5-azacytidine as the demethylation agent. By using CpG Plot (European Bioinformatics Institute, U.K.), CpG islands of KLK1 and KLKB1 were located, in order to obtain a clear map of their location and likely association with the promoter, putative promoter, and transcription sites ( Fig.…”

“…By using CpG Plot (European Bioinformatics Institute, U.K.), CpG islands of KLK1 and KLKB1 were located, in order to obtain a clear map of their location and likely association with the promoter, putative promoter, and transcription sites ( Fig. 10.4; Wong et al, 2011).…”

“…Mapping indicated a total of five CpG islands in introns 4, 5, 6, and 11. Adapted fromWong et al (2011).…”

Epigenetic regulation of kallikrein-related peptidases: there is a whole new world out there

“…A number of studies have investigated the relationship between KLK gene methylation and expression using 5-aza-2 ′ -deoxycytidine (5-aza-dC), a cytosine analog that reduces DNA methylation. These studies have demonstrated that treating cell lines derived from hepatocellular carcinoma, prostate, breast, ovarian, cervix, gastric and lung cancer, with 5-aza-dC can induce the expression of KLK genes 1, 5, 6, 10, 11, 12 and 13; thus establishing that DNA methylation plays a role in regulating their expression (Li et al , 2001 ;Roman -Gomez et al, 2004 ;Sidiropoulos et al , 2005 ;Pampalakis et al , 2006b ;Pampalakis and Sotiropoulou , 2006a ;Huang et al , 2007 ;Kioulafa et al , 2009 ;Lu et al , 2009 ;Pampalakis et al , 2009 ;Zhang et al , 2010 ;Chou et al , 2011 ;Wong et al , 2011 ). Interestingly, KLK6 has been included in these studies although it does not contain a CpG island.…”