Recent genome-wide association studies reported strong and reproducible associations of multiple genetic variants in a large ''gene-desert'' region of chromosome 8q24 with susceptibility to prostate cancer (PC). However, the causative or functional variants of these 8q24 loci and their biological mechanisms associated with PC susceptibility remain unclear and should be investigated. Here, focusing on its most centromeric region (so-called Region 2: Chr8: 128.14-128.28 Mb) among the multiple PC loci on 8q24, we performed fine mapping and re-sequencing of this critical region and identified SNPs (single nucleotide polymorphisms) between rs1456315 and rs7463708 (chr8: 128,173,119-128,173,237 bp) to be most significantly associated with PC susceptibility (P = 2.00 · 10 )24, OR = 1.74, 95% confidence interval = 1.56-1.93). Importantly, we show that this region was transcribed as a 13 kb intron-less long non-coding RNA (ncRNA), termed PRNCR1 (prostate cancer non-coding RNA 1), and PRNCR1 expression was upregulated in some of the PC cells as well as precursor lesion prostatic intraepithelial neoplasia. Knockdown of PRNCR1 by siRNA attenuated the viability of PC cells and the transactivation activity of androgen receptor, which indicates that PRNCR1 could be involved in prostate carcinogenesis possibly through androgen receptor activity. These findings could provide a new insight in understanding the pathogenesis of genetic factors for PC susceptibility and prostate carcinogenesis. (Cancer Sci 2011; 102: 245-252)

Keloid is a dermal fibroproliferative growth that results from dysfunction of the wound healing processes. Through a multistage genome-wide association study using 824 individuals with keloid (cases) and 3,205 unaffected controls in the Japanese population, we identified significant associations of keloid with four SNP loci in three chromosomal regions: 1q41, 3q22.3-23 and 15q21.3. The most significant association with keloid was observed at rs873549 (combined P = 5.89 x 10(-23), odds ratio (OR) = 1.77) on chromosome 1. Associations on chromosome 3 were observed at two separate linkage disequilibrium (LD) blocks: rs1511412 in the LD block including FOXL2 with P = 2.31 x 10(-13) (OR = 1.87) and rs940187 in another LD block with P = 1.80 x 10(-13) (OR = 1.98). Association of rs8032158 located in NEDD4 on chromosome 15 yielded P = 5.96 x 10(-13) (OR = 1.51). Our findings provide new insights into the pathophysiology of keloid formation.

Prostate cancer often relapses during androgen-depletion therapy, even under conditions in which a drastic reduction of circulating androgens is observed. There is some evidence that androgens remain present in the tissues of hormone-refractory prostate cancers (HRPC), and enzymes involved in the androgen and steroid metabolic pathway are likely to be active in HRPC cells. We previously carried out a genome-wide gene expression profile analysis of clinical HRPC cells by means of cDNA microarrays in combination with microdissection of cancer cells and found dozens of transactivated genes. Among them, we here report the identification of a novel gene, SRD5A2L, encoding a putative 5α α α α-steroid reductase that produces the most potent androgen, 5α α α α-dihydrotestosterone (DHT), from testosterone. Liquid chromatography-tandem mass spectrometry analysis following an in vitro 5α α α α-steroid reductase reaction validated its ability to produce DHT from testosterone, similar to type 1 5α α α α-steroid reductase. Because two types of 5α α α α-steroid reductase were previously reported, we termed this novel 5α α α α-steroid reductase 'type 3 5α α α α-steroid reductase' (SRD5A3). Reverse transcription-polymerase chain reaction and northern blot analyses confirmed its overexpression in HRPC cells, and indicated no or little expression in normal adult organs. Knockdown of SRD5A3 expression by small interfering RNA in prostate cancer cells resulted in a significant decrease in DHT production and a drastic reduction in cell viability. These findings indicate that a novel type 3 5α α α α-steroid reductase, SRD5A3, is associated with DHT production and maintenance of androgen-androgen receptor-pathway activation in HRPC cells, and that this enzymatic activity should be a promising molecular target for prostate cancer therapy. (Cancer Sci 2008; 99: 81-86)

We previously reported MELK (maternal embryonic leucine zipper kinase) as a novel therapeutic target for breast cancer. MELK was also reported to be highly upregulated in multiple types of human cancer. It was implied to play indispensable roles in cancer cell survival and indicated its involvement in the maintenance of tumor-initiating cells. We conducted a high-throughput screening of a compound library followed by structure-activity relationship studies, and successfully obtained a highly potent MELK inhibitor OTSSP167 with IC50 of 0.41 nM. OTSSP167 inhibited the phosphorylation of PSMA1 (proteasome subunit alpha type 1) and DBNL (drebrin-like), which we identified as novel MELK substrates and are important for stem-cell characteristics and invasiveness. The compound suppressed mammosphere formation of breast cancer cells and exhibited significant tumor growth suppression in xenograft studies using breast, lung, prostate, and pancreas cancer cell lines in mice by both intravenous and oral administration. This MELK inhibitor should be a promising compound possibly to suppress the growth of tumor-initiating cells and be applied for treatment of a wide range of human cancer.

A number of epidemiologic studies have indicated a strong association between dietary fat intake and prostate cancer development, suggesting that lipid metabolism plays some important roles in prostate carcinogenesis and its progression. In this study, through our genome-wide gene expression analysis of clinical prostate cancer cells, we identified a novel lipogenic gene, ELOVL7, coding a possible long-chain fatty acid elongase, as overexpressed in prostate cancer cells. ELOVL7 expression is regulated by the androgen pathway through SREBP1, as well as other lipogenic enzymes. Knockdown of ELOVL7 resulted in drastic attenuation of prostate cancer cell growth, and it is notable that high-fat diet promoted the growth of in vivo tumors of ELOVL7-expressed prostate cancer. In vitro fatty acid elongation assay and fatty acid composition analysis indicated that ELOVL7 was preferentially involved in fatty acid elongation of saturated verylong-chain fatty acids (SVLFA, C20:0f). Lipid profiles showed that knockdown of ELOVL7 in prostate cancer cells affected SVLFAs in the phospholipids and the neutral lipids, such as cholesterol ester. Focusing on cholesterol ester as a source of de novo steroid synthesis, we show that ELOVL7 affected de novo androgen synthesis in prostate cancer cells. These findings suggest that EVOLV7 could be involved in prostate cancer growth and survival through the metabolism of SVLFAs and their derivatives, could be a key molecule to elucidate the association between fat dietary intake and prostate carcinogenesis, and could also be a promising molecular target for development of new therapeutic or preventive strategies for prostate cancers. [Cancer Res 2009;69(20):8133-40]