A Kallikrein 15 (KLK15) single nucleotide polymorphism located close to a novel exon shows evidence of association with poor ovarian cancer survival.

BACKGROUND: KLK15 over-expression is reported to be a significant predictor of reduced progression-free survival and overall survival in ovarian cancer. Our aim was to analyse the KLK15 gene for putative functional single nucleotide polymorphisms (SNPs) and assess the association of these and KLK15 HapMap tag SNPs with ovarian cancer survival. RESULTS: In silico analysis was performed to identify KLK15 regulatory elements and to classify potentially functional SNPs in these regions. After SNP validation and identification by DNA sequencing of ovarian cancer cell lines and aggressive ovarian cancer patients, 9 SNPs were shortlisted and genotyped using the Sequenom iPLEX Mass Array platform in a cohort of Australian ovarian cancer patients (N = 319). In the Australian dataset we observed significantly worse survival for the KLK15 rs266851 SNP in a dominant model (Hazard Ratio (HR) 1.42, 95% CI 1.02-1.96). This association was observed in the same direction in two independent datasets, with a combined HR for the three studies of 1.16 (1.00-1.34). This SNP lies 15 bp downstream of a novel exon and is predicted to be involved in mRNA splicing. The mutant allele is also predicted to abrogate an HSF-2 binding site. CONCLUSIONS: We provide evidence of association for the SNP rs266851 with ovarian cancer survival. Our results provide the impetus for downstream functional assays and additional independent validation studies to assess the role of KLK15 regulatory SNPs and KLK15 isoforms with alternative intracellular functional roles in ovarian cancer survival.

Kallikrein-related peptidase 10 (KLK10) expression and single nucleotide polymorphisms in ovarian cancer survival.

INTRODUCTION: Kallikrein-related peptidase 10 (KLK10) overexpression is a predictor of poor disease outcome in women with late-stage ovarian cancer. We aimed to identify whether KLK10 overexpression could be attributed to genetic variants, in particular, in hormone response elements or transcription factor binding sites. METHODS: Cox regression analysis was used to assess the association between 2 tag and 1 exonic KLK10 single nucleotide polymorphisms (SNPs) and the survival of 319 patients with ovarian cancer. Four different ovarian cancer cell lines were investigated for KLK10 expression after hormone stimulation, and sequence variation in the 3.6-Kb upstream of the KLK10 start site. In silico analyses of SNPs in cell lines and from published databases were undertaken to identify further research novel and potentially functional SNPs that are not covered by tag SNPs. RESULTS: The KLK10 SNPs investigated were not associated with ovarian cancer survival. However, steroid hormone treatment of ovarian cell lines showed KLK10 up-regulation in response to estrogen and estrogen plus progesterone treatments in the aggressive cell line PEO1 and affirmed a role for KLK10 in aggressive ovarian cancer. Potentially functional KLK10 SNPs were identified by cell line sequencing and bioinformatic analysis. CONCLUSION: Potentially functional candidate KLK10 SNPs require investigation in future association studies of ovarian cancer risk and survival, including rs3760738 identified in aggressive ovarian cancer cell lines and predicted to affect transcription factor binding sites.

Kallikrein-related peptidase 7 promotes multicellular aggregation via the alpha(5)beta(1) integrin pathway and paclitaxel chemoresistance in serous epithelial ovarian carcinoma.

Kallikrein-related peptidase 7 (KLK7) is upregulated in epithelial ovarian carcinoma (EOC) with high levels correlated with poor prognosis. However, the mechanisms underlying this relationship and the role of KLK7 in EOC progression are unknown. We report that two different KLK7 transcripts, KLK7-253 and KLK7-181, are simultaneously expressed in high-grade serous EOC. Multicellular aggregates (MCA), which promote cell survival and chemoresistance, were observed in SKOV-3 cells stably overexpressing KLK7-253 in particular. Importantly, these MCAs invade into a monolayer of mesothelial cells and form cancer cell foci. Blocking MCA using antibodies against KLK7 and alpha(5)beta(1) and beta(1) integrins confirmed the involvement of KLK7 and integrin-regulated cell adhesion. Increased levels of alpha(5)/beta(1) integrins and enhanced attachment to fibronectin and vitronectin, which was blocked with an anti-beta(1) integrin antibody, were also observed. Finally, Western blot and immunohistochemistry showed higher KLK7 and alpha(5)/beta(1) integrin levels in serous EOC cells from ascites and tumor samples from chemotherapy nonresponders with short postsurvival times. Additionally, both KLK7-253 and KLK7-181 clones were more resistant to paclitaxel treatment in vitro. These findings suggest a mechanism for the association of high KLK7 levels with chemoresistance and poor prognosis for serous EOC patients by promotion of peritoneal dissemination and reinvasion via increased MCA and alpha(5)beta(1) integrin-dependent cell adhesion.

Expression of PSA-RP2, an alternatively spliced variant from the PSA gene, is increased in prostate cancer tissues but the protein is not secreted from prostate cancer cells.

PSA-RP2 is a variant transcript expressed from the PSA gene that is conserved in gorillas, chimpanzees and humans suggesting a particular relevance for this transcript in these primates. We demonstrated by qRT-PCR that PSA-RP2 is upregulated in prostate cancer compared with benign prostatic hyperplasia tissues. The PSA-RP2 protein was not detected in seminal fluid and was cytoplasmically localised but not secreted from LNCaP or transfected PC3 prostate cells, despite secretion from transfected Cos-7 and HEK293 kidney cell lines. PSA-RP2-transfected PC3 cells showed slightly decreased proliferation and increased migration towards PC3-conditioned medium that could suggest a functional role in prostate cancer.

A novel transcript from the KLKP1 gene is androgen regulated, down-regulated during prostate cancer progression and encodes the first non-serine protease identified from the human kallikrein gene locus.

BACKGROUND: The kallikrein-related (KLK) serine protease, prostate specific antigen is the current marker for prostate cancer (PCa). Other members of the KLK family are also emerging as potential adjunct biomarkers for this disease. Our aim was to identify and characterize novel KLK-related genes with potential as PCa bio-markers. METHODS: Low stringency DNA screening was coupled with amplification techniques to identify novel sequences. Transcripts were examined by Northern blot, RT-PCR, and in situ hybridization analysis and in silico bioinformatics approaches. Protein characterization was performed by Western blot and confocal microscopy analysis. Gene regulation studies were performed by quantitative PCR and promoter reporter assays. RESULTS: We identified a novel kallikrein-related mRNA designated KRIP1 (kallikrein-related, expressed in prostate 1) which, together with the recently reported PsiKLK1 and KLK31P transcripts, is transcribed from KLKP1; a gene evolved from, and located within, the KLK locus. Significantly, in contrast to these other non-coding KLKP1 transcripts, the KRIP1 mRNA generates an approximately 18 kDa intracellular protein-the first non-serine protease identified from the KLK locus. KRIP1 mRNA is abundant only in normal prostate and is restricted to cells of epithelial origin in normal and diseased glands. Ligand binding of the androgen receptor increases transcription from the KLKP1 gene. Consistently, KRIP1 mRNA levels are lower in PCa samples compared to benign prostatic hyperplasia. CONCLUSIONS: Transcription from KLKP1 is reduced as cells de-differentiate on the pathway to malignancy. KLKP1/KRIP1 has potential as a marker of both PCa progression and recent evolutionary events within the KLK locus.

Kallikrein-related peptidase (KLK) family mRNA variants and protein isoforms in hormone-related cancers: do they have a function?

The kallikrein-related peptidase (KLK) gene family of 15 serine proteases encodes many proteins, including prostate specific antigen (PSA or KLK3), that are well described and/or are potential biomarkers for hormone-related cancers. Variant mRNA transcripts produced by alternative splicing, polyadenylation or AUG sites, or intron retention have been found for each of the KLK genes. The predicted protein for many of these alternative transcripts is different from that of the classical kallikrein-related peptidases and would not be an active serine protease. The majority of these novel protein isoforms have not been studied in vivo. The possible function(s) of the variant transcripts/protein isoforms and potential roles that they may play in hormone-related cancers are still unknown and are the focus of this short review.

Incessant ovulation, inflammation and epithelial ovarian carcinogenesis: revisiting old hypotheses.

Epithelial ovarian cancer (EOC) is often a lethal disease because in many cases early symptoms go undetected. Although research proceeds apace, as yet there are few reliable and specific biomarkers for the early stages of the disease. EOC is an umbrella label for a highly heterogeneous collection of cancers, which includes tumours of low malignant potential, serous cystadenomas, mucinous and clear cell carcinomas, all of which are likely to arise from a number of epithelial cell types and a variety of progenitor lesions. Many, but not all types of EOC are thought to arise from the cells lining ovarian inclusion cysts. In this review, we discuss the hypotheses that have driven our ideas on epithelial ovarian carcinogenesis and examine the morphological and genetic evidence for pathways to EOC. The emergence of laser-capture microdissection and expression profiling by microarray technologies offers the promise of defining these pathways more accurately, as well as providing us with the tools for earlier diagnosis.

Location of inclusion cysts in mouse ovaries in relation to age, pregnancy, and total ovulation number: implications for ovarian cancer?

Benign ovarian cysts are thought to be precursor lesions that differentiate and transform into carcinoma. With the aim of testing the hypothesis that increased ovulation number increases the frequency or number of ovarian cysts, the development and appearance of ovarian cysts was investigated in mice of differing ages and total lifetime ovulation number. High total ovulation number was induced by keeping mice in cages divided by a screen, with a male on one side and two females on the other side. Significantly more cysts were observed in animals subjected to incessant ovulation for 8 months and in 12 month breeding mice than in 3-month virgin mice or 1-month prepubertal animals. These cysts had the appearance of benign serous inclusion cysts. When cystic ovaries were serial sectioned, 47% of cysts had a connection to the ovarian hilus and potentially to the tubules of the rete ovarii, 31% were adjacent to the hilus, and 22% had an intra-ovarian location. A significant increase in intra-ovarian cysts was observed in the 8-month incessant ovulation group, implying that high ovulation number leads to ovarian surface invagination and inclusion cyst formation. In conclusion, ovarian inclusion cysts may be derived from more than one epithelial source, but incessant ovulation may increase the proportion derived from the ovarian surface epithelium. Because the cysts observed resembled human serous inclusion cysts these results have possible implications for epithelial ovarian carcinoma.