Hitoshi Ishiguro

Gene expression analysis of renal carcinoma: adipose differentiation-related protein as a potential diagnostic and prognostic biomarker for clear-cell renal carcinoma

The gene expression profiles of 33 renal cell carcinomas (RCCs) and nine normal kidney samples were examined using high‐density oligonucleotide microarrays in an attempt to identify biomolecular markers for the diagnosis of tumour subtypes and also for prediction of prognosis. Hierarchical clustering demonstrated that clear‐cell RCC, chromophobe RCC, and normal kidney tissue showed distinctive gene expression profiles. The mean expression levels of 149 of 12 500 genes were more than three times higher in clear‐cell RCC than in chromophobe RCC and normal kidney tissue. Among the genes whose expression was upregulated in clear‐cell RCC, adipose differentiation‐related protein (ADFP) and nicotinamide N‐methyltransferase (NNMT) were selected for further analysis. Consistent with the results of the microarray, increased levels of ADFP and NNMT mRNA were found more frequently in clear‐cell RCCs than in other non‐clear‐cell tumour subtypes using real‐time quantitative PCR. Immunohistochemistry for ADFP showed strong and unique tumour cell staining patterns in the majority of clear‐cell RCCs. More importantly, patients bearing tumours with higher AFDP mRNA levels showed significantly better survival in both univariate and multivariate analyses. ADFP is a lipid storage droplet‐associated protein and its transcription is considered to be regulated by the von Hippel–Lindau/hypoxia‐inducible factor pathway. It is known that clear‐cell RCC contains abundant lipids and cholesterols. Thus it is likely that sustained upregulation of ADFP following VHL inactivation is involved in the morphological appearance of clear‐cell RCC. Moreover ADFP expression status may provide useful prognostic information as a biomolecular marker in patients with clear‐cell RCC. Copyright

Stable Suppression of Tumorigenicity by Pin1-Targeted RNA Interference in Prostate Cancer

Purpose: The peptidyl-prolyl isomrase Pin1 plays a catalytic role in oncogenesis in solid cancers, including prostate cancer. In the present study, we sought to determine the potential of Pin1-targeted gene silencing in inhibiting cellular growth and tumorigenicity in prostate cancer. Experimental Design: A retrovirus-mediated RNA interference targeting Pin1 was expressed in PC3 and LNCaP cells, and cell growth and several transformed properties were investigated. Results: The stable expression of Pin1-specific small interfering RNA constructs in PC3 and LNCaP cells significantly reduced cellular proliferation, colony formation, migration, and invasion but strongly enhanced the apoptotic response induced by serum depletion or treatment with anticancer agents. Furthermore, Pin1 depletion significantly suppressed tumorigenic potential in athymic mice, resulting in the inhibition of both tumor growth and angiogeneisis. Conclusions: These results strongly suggest that Pin1 plays an important role not only in tumorigenesis but also in the maintenance of the transformed phenotype in prostate cancer cells. Hence, Pin1 may serve as a promising therapeutic target, particularly for recurrent prostate tumors.

The overexpression and altered localization of the atypical protein kinase C λ/ι in breast cancer correlates with the pathologic type of these tumors

Breast cancer is one of the common malignant diseases among women in Japan as well as in western countries, and its incidence continues to increase. Normal mammary duct epithelial cells exhibit a well-organized apicobasal polarity, which forms the basis for their specific structure and function. Although the loss of epithelial cell polarity is one of the major changes that occur during the progression of tumor cells, including breast cancer, the underlying molecular mechanisms for this, as well as their relationship to other changes such as increased proliferation and metastasis, remain to be elucidated. The atypical protein kinase C lambda/iota (aPKC lambda/iota) is involved in several signal transduction pathways, including the establishment of epithelial cell polarity. In this study we evaluated the expression and localization of aPKC lambda/iota in breast cancer by immunohistochemistry and compared our findings with the clinicopathologic factors associated with the tumor specimens. We detected aPK Clambda/iota protein overexpression in 88 of the 110 breast cancer cases (80.0%) under study, expect for decreased expression in a few cases. The immunoreactivity of aPK Clambda/iota was generally weak in ductal carcinoma in situ, but strong in invasive ductal carcinoma (IDC; P = .022). The correlation between apical or cytoplasmic aPKC lambda/iota localization and tumor pathologic type (ie, atypical ductal hyperplasia, ductal carcinoma in situ. or IDC) was also demonstrated (P < .001). These results thus indicate that the normal apicobasal polarity is lost upon the progression of a breast lesion to IDC. This is also the first evidence to show aPKC lambda/iota overexpression in breast cancer and demonstrates that its localization is associated with the trend of pathologic type of the tumor.

Antiproliferative activity of angiotensin II receptor blocker through cross-talk between stromal and epithelial prostate cancer cells

We showed previously that angiotensin II activated the proliferation of prostate cancer cells and that angiotensin II receptor blockers (ARB) could inhibit it. Here, we investigated whether angiotensin II exerts mitogenic effects on the cross-talk between stromal and cancer cells and whether an ARB can inhibit tumor growth through actions on stromal cells. Cell proliferation and interleukin-6 secretion of prostate stromal PrSC cells stimulated with angiotensin II, tumor necrosis factor-α, or epidermal growth factor were examined in the absence and presence of ARB. We examined the effect of ARB on mitogen-activated protein kinase (MAPK) phosphorylation of PrSC and PC-3 cells treated with conditioned medium of PrSC cells and determined the effect of ARB on tumor growth induced by paracrine factors from PrSC cells. Angiotensin II activated the cell proliferation and interleukin-6 secretion of PrSC cells, and ARB inhibited it. Angiotensin II, tumor necrosis factor-α, or epidermal growth factor induced MAPK phosphorylation in PrSC cells, and this phosphorylation was inhibited by ARB. Conditioned medium of PrSC cells with angiotensin II activated MAPK phosphorylation in PC-3 cells, and ARB-treated conditioned medium of PrSC cells inhibited it. The tumor growth and angiogenesis of a mixture of PC-3 with PrSC were inhibited by ARB administration, whereas those of PC-3 xenografts were not inhibited. ARB exerted an antiproliferative effect on prostate cancer through paracrine factors from stromal cells. Because prostate stromal cells are thought to be involved in the initiation and development of prostate cancer, the present data suggest the possibility that ARBs are a novel therapeutic class of agents for prostate cancer.

Genistein induces cell growth inhibition in prostate cancer through the suppression of telomerase activity

Abstract Aim:  To clarify the mechanism of the anticancer effect of genistein, we examined the effect of genistein on telomerase activity in prostate cancer cells. We hypothesized that genistein may exert its anticancer effect by modifying telomerase activity in prostate cancer cells.

Usefulness of the 2005 International Society of Urologic Pathology Gleason grading system in prostate biopsy and radical prostatectomy specimens

To determine whether the 2005 International Society of Urologic Pathology (ISUP) Gleason Grading Consensus is clinically more useful than the conventional Gleason score (CGS), we compared the CGS and ISUP GS (IGS) of prostate needle biopsy (NB) and radical prostatectomy (RP) specimens, and evaluated the prognostic value of the ISUP GS.

aPKCλ/ι promotes growth of prostate cancer cells in an autocrine manner through transcriptional activation of interleukin-6

Understanding the mechanism by which hormone refractory prostate cancer (HRPC) develops remains a major issue. Alterations in HRPC include androgen receptor (AR) changes. In addition, the AR is activated by cytokines such as interleukin-6 (IL-6). Atypical protein kinase C (aPKCλ/ι) has been implicated in the progression of several cancers. Herein, we provide evidence that aPKCλ/ι expression correlates with prostate cancer recurrence. Experiments in vitro and in vivo revealed aPKCλ/ι to be involved in prostate cancer cell growth through secretion of IL-6. Further, aPKCλ/ι activates transcription of the IL-6 gene through NFκB and AP-1. We conclude that aPKCλ/ι promotes the growth of hormone independent prostate cancer cells by stimulating IL-6 production in an autocrine manner. Our findings not only explain the link between aPKCλ/ι and IL-6, implicated in the progression a variety of cancers, but also establish a molecular change involved in the development of HRPC. Further, aPKCλ/ι expression might be a biomarker for prostate cancer progression.

Pilot study of angiotensin II receptor blocker in advanced hormone-refractory prostate cancer.

BackgroundWe previously demonstrated that an angiotensin II receptor blocker (ARB) had the potential to inhibit cell proliferation of prostate cancer. In this study, we examined whether an ARB could elicit an antiproliferative effect on hormone-refractory prostate cancer, clinically.MethodsTwenty-three patients with advanced hormone-refractory prostate cancer who had already received secondary hormonal therapy using dexamethasone, and who were no longer receiving conventional therapy, were enrolled. All of the patients received candesartan 8 mg once daily per os and, simultaneously, androgen ablation. Change in prostate-specific antigen (PSA) was determined as the primary endpoint. The secondary end-point was change in performance status (PS). To investigate angiotensin II type 1 (AT1) receptor expression in prostate cancer tissue, real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was performed, using specimens, from untreated patients with prostate cancer.ResultsEight patients (34.8%) showed responsive PSA changes; six showed a decrease immediately after starting administration and two showed a stable level of PSA. Six men with a PSA decline of more than 50% showed an improvement in PS. The mean time to PSA progression (TTPP) in responders was 8.3 months (range, 1–24 months). Half of the patients showed stable or improved PS during treatment. With regard to toxic effects, only one patient showed hypotension during treatment. The RT-PCR showed that AT1 receptor expression in well-differentiated adenocarcinoma was higher than that in poorly differentiated adenocarcinoma.ConclusionThese data showed that an ARB had potential biological effects on prostate cancer, suggesting the usefulness of the cytostatic activity of such agents on recurrent prostate cancer.

Antiproliferative Efficacy of Angiotensin II Receptor Blockers in Prostate Cancer

An apparent low prevalence of cancer in hypertensive patients receiving angiotensin converting enzyme inhibitors is reported; however, the molecular mechanisms have not been elucidated. Angiotensin-II (Ang-II) is well known to be associated with hypertension, as a main peptide of the renin-angiotensin system, and its detailed molecular mechanisms have recently been elucidated. For instance, Ang-II directly activates the mitogenic signal transduction pathway through the angiotensin-II type-1 (AT1) receptor in smooth muscle cells and cardiac myocytes. Ang-II receptor blockers (ARBs), a class of antihypertensive agent, suppress signal transduction pathways mediated by growth factors such as epidermal growth factor (EGF), through the AT1 receptor. Our studies demonstrated that an ARB had the potential for antiproliferative effects and inhibition of angiogenesis in prostate cancer cells. The AT1 receptor is categorized in the guanosine phosphate binding protein-coupled receptors (GPCRs), which are viewed as critical regulators of the interactions between epithelial and stromal cells. Hence, we consider that in overcoming prostate cancer, it is very important to inhibit GPCR signaling in cancer cells by ARBs. It is unclear how prostate cancer growth changes from being hormone dependent to independent, and no effective therapy has therefore been developed. Our clinical data revealed that ARB administration decreased prostate specific antigen (PSA) and improved performance status in patients with hormone-refractory prostate cancer. This review provides an insight into the key role of Ang-II and the possibility of ARBs for molecular targeting of mitogenesis and angiogenesis in prostate cancer.

Alterations of p16 and p14ARF genes and their 9p21 locus in oral squamous cell carcinoma.

The p16 gene encodes a 16-kDa cyclin kinase inhibitor, and the p14ARF gene a 14-kDa protein, which acts as a cell cycle regulator or tumor suppressor in human cancer cells. Both genes are mapped on chromosome 9p21. Previous studies have suggested that the p16 gene has important roles in head and neck squamous cell carcinoma. To clarify carcinogenesis in oral squamous cell carcinoma (OSCC), we examined 44 primary OSCCs for alterations of p16 and p14ARF mRNA expression, the methylation status of the p16 gene promoter, the loss of heterozygosity (LOH) at the 9p21 locus, and p16 and p14ARF gene mutations. Alterations of p16 and p14ARF mRNA expression were seen in 27 (61.4%) of 44 and 10 (22.7%) of 44 of OSCC samples, respectively. Methylation of the p16 gene promoter region was detected in 28 (63.6%) of 44 samples, and LOH at 9p21 locus was found in 30 (68.2%) of 44. p16 and p14ARF gene mutations were observed in 4 (9.0%) of 44 and 2 (4.5%) of 44 samples, respectively. Suspected homozygous deletion (HD) was seen in 9 (20.5%) of 44. All cases except one (97.7%) showed alterations in p16, p14ARF, and their locus. These data indicate that the status of p16 and p14ARF genes in OSCC is frequently influenced by methylation, gene mutation, and allelic deletions. Furthermore, these genes and their 9p21 locus have various roles in the pathogenesis of OSCC.