Downregulation of human kallikrein 10 (KLK10/NES1) by CpG island hypermethylation in breast, ovarian and prostate cancers.
OBJECTIVE
The human kallikrein 10 (KLK10)/normal epithelial cell-specific-1 (NES1) gene is highly expressed in normal mammary, ovary and prostate cells, but its expression is dramatically decreased in cancer cell lines. Recently, it has been shown that CpG island hypermethylation of the KLK10 gene is responsible for the tumor-specific loss of KLK10 gene expression in certain breast cancer cell lines.


METHODS
We examined the role of CpG island hypermethylation in the tumor-specific loss of KLK10 expression in breast, ovarian and prostate cancers. We treated cells with the demethylating agent 5-aza-2'-deoxycytidine (dC) and monitored changes in KLK10 mRNA by RT-PCR and secreted hK10 protein expression by ELISA. The following cell lines were used: MDA-MB-231, MDA-MB-468, MCF-7, ZR-75-1, T-47D and BT-474 (breast); BG-1, MDAH-2774, HTB-75, HTB-161, PA-1 and ES-2 (ovary), and LNCaP and PC-3 (prostate).


RESULTS
Upregulation of KLK10 mRNA levels, which was accompanied by an increase in secreted hK10 protein concentration, was observed for a subset of breast, ovarian, and prostate tumor cell lines after 5-aza-2'-dC. Genomic sequencing of sodium-bisulfite-treated DNA demonstrated that CpG sites within the KLK10 gene exon 3 were highly methylated. Hypermethylation of exon 3 CpG regions was also detected in primary ovarian cancers.


CONCLUSIONS
These data suggest that CpG island hypermethylation plays an important role in the downregulation of kallikrein 10 mRNA and protein expression, but it cannot explain the pattern of expression of this gene in all cell lines or tissue tested.
Sidiropoulos
Michael
M
Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Canada.
Pampalakis
Georgios
G
Sotiropoulou
Georgia
G
Katsaros
Dionyssios
D
Diamandis
Eleftherios P
EP
D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D018899:CpG Islands / Q000235:genetics*; D003596:Cytosine / Q000378:metabolism; D019175:DNA Methylation; D015536:Down-Regulation / Q000235:genetics; D005091:Exons / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007610:Kallikreins / Q000235:genetics* / Q000378:metabolism; D008297:Male; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D012333:RNA, Messenger; D003596:Cytosine; C100936:KLK10 protein, human; D007610:Kallikreins