Expression analysis and study of the KLK15 mRNA splice variants in prostate cancer and benign prostatic hyperplasia

Abstract

Prostate cancer is the most commonly diagnosed malignancy in male populations in the Western world. The KLK15 gene, the newest member of the kallikrein family, is expressed in the prostate gland. The purpose of this study is the expression analysis and the clinical evaluation of the KLK15 mRNA spliced variants in prostate cancer (CaP) and benign prostatic hyperplasia (BPH) patients. Total RNA was isolated from 104 CaP and BPH tissue specimens. After testing the quality of the RNA, cDNA was produced by reverse transcription, and PCR was performed for the amplification of the KLK15 mRNA transcripts. GAPDH and HPRT genes were used as endogenous controls. Our data revealed that mRNA spliced variants of KLK15 were differentially expressed in prostate tissue specimens. Analysis of data showed a statistically significant (P < 0.001) increase in the frequency of overexpression of KLK15 transcripts encoding for both the active isoform and for the isoform 3 in CaP compared to BPH samples. Furthermore, KLK15 transcripts were found to be highly expressed in more aggressive tumors (P = 0.017). These results suggest that KLK15 expression analysis could be employed as a valuable tool for the discrimination between BPH and CaP tissue specimens and as an unfavorable prognostic marker for prostate cancer. (Cancer Sci 2010; 101: 693-699) P rostate cancer (CaP) is the most common non-skin male malignancy, accounting for almost 33% of all cancer incidents. Also, it is the second-most common cause of cancer-related deaths in most Western countries.(1,2) Although many risk factors, such as alterations in androgen biosynthesis and metabolism, and diet and chronic inflammation, have been associated with the disease, the etiology of prostate cancer remains uncertain.(1,3,4) The most common form of the disease is sporadic prostate cancer, which is expected to be developed by non-random somatic genome alterations such as loss or gain of chromosomal regions (6q, 7q, 8p), abnormal DNA methylation, mutations of oncogenes (EGFR, MYC) and tumor suppressor genes (NXK3.1, GSTP1), and alterations regarding the androgen receptor (AR).(2,5-7) AR is an intracellular ligand-dependent transcription factor, which plays an essential role in the survival and growth of prostate cells, as well as in the initiation and the progression of prostate tumors. As a result, the disease treatment aims at the regulation and manipulation of the AR metabolic pathway. However, AR function evolves as the cell changes toward a clinical androgen-depletion independent state. (8,9) Recently published data show that benign prostatic hyperplasia (BPH) occurs to about 8% of men aged from 31 to 40 years, to one-quarter of men in their 50s, to one-third of men in their 60s, to about half of all men aged 80 years or older and increases to about 90% by the ninth decade of life. (10) Since the discovery of prostate-specific antigen (PSA) also known as, kallikrein (KLK) 3 routine PSA testing has become the mainstay of prostate cancer detection.(11) However, PSA lacks diagnostic sp...

Kallikrein-related peptidases in prostate, breast, and ovarian cancers: from pathobiology to clinical relevance

“…Additionally, elevated KLK14 expression is associated with late-stage and high-Gleason-score tumors (Yousef et al , 2003e ), whereas patients with higher KLK14 levels exhibit increased risk for relapse after radical prostatectomy (Rabien et al , 2008 ). Moreover, increased KLK4 (Avgeris et al , 2011b ) and KLK15 (Mavridis et al , 2010a ) mRNA levels have been associated with high-Gleason-score and advanced-stage tumors, supporting, in this way, their unfavorable prognostic nature for the patients. Moreover, KLK15 tissue protein levels are associated with patients ' biochemical relapse (Rabien et al , 2010 ).…”

“…Apart from their physiological roles, PARs can intervene in cancer-associated molecular cascades affecting cell proliferation and migration (Hollenberg et al , 2008 ;Oikonomopoulou et al , 2010b ). Given that IGFBPs and PARs are well-documented substrates of KLKs, an abnormal Kwiatkowski et al , 1998 ;Magklara et al , 1999 ;Nam et al , 2000 ;Steuber et al , 2007 PSA/KLK3 Screening; diagnosis; treatment monitoring; unfavorable prognosis Stephan et al , 2007 ;Lilja et al , 2008 ;Ulmert et al , 2009 ;Avgeris et al , 2010 KLK4 Unfavorable prognosis Avgeris et al , 2011b KLK5 Favorable prognosis Yousef et al , 2002b ;Korbakis et al , 2009 KLK11 Diagnosis; favorable prognosis Diamandis et al , 2002 ;Nakamura et al , 2003a,b ;Bi et al , 2010 KLK14 Unfavorable prognosis Yousef et al , 2003e ;Rabien et al , 2008 KLK15 Unfavorable prognosis Mavridis et al , 2010a ;Rabien et al , 2010 Breast cancer PSA/KLK3 Diagnosis; treatment response; favorable prognosis Yu et al , 1998 ;Foekens et al , 1999 ;Black et al , 2000 ;Sauter et al , 2004a Kim et al , 2001 ;Diamandis et al , 2003a ;Dong et al , 2003 ;Yousef et al , 2003b ;Oikonomopoulou et al , 2008b ;Dorn et al , 2011a,b KLK6 Diagnosis; unfavorable prognosis Diamandis et al , 2000Diamandis et al , , 2003bHoffman et al , 2002 ;Shih Ie et al , 2007 ;Kountourakis et a...…”

Emerging clinical importance of the cancer biomarkers kallikrein-related peptidases (KLK) in female and male reproductive organ malignancies

“…Increase of three KLKs (KLK2, 14 and 15) is associated with poor prognosis; KLK4 is a marker of a favorable prognosis. Decreased mRNA or protein levels of KLK2, 3, 5–7, 10, 11, 13 and 15 have been reported of which KLK3 and 15 are markers of a poor prognosis and KLK5 and 11 markers of a favorable prognosis 70,83,84…”

Association between Prostinogen (KLK15) Genetic Variants and Prostate Cancer Risk and Aggressiveness in Australia and a Meta-Analysis of GWAS Data

“…KLK15 (also called Prostinogen) is the most recently cloned member of the human Kallikrein gene family and is adjacent to KLK3/prostate specific antigen (PSA) in genetic location [10], [11]. KLK15 has been reported to be upregulated at the mRNA level in prostate cancer [11], [12], [13] and has been described as an unfavorable prognostic marker for prostate cancer progression following radical prostatectomy [14]. KLK15 has also been reported to be a significant predictor of reduced progression-free survival and overall survival in ovarian cancer [15] and a favorable prognostic marker for breast cancer [16].…”