Domenico D'Arca

Clusterin (SGP‐2, ApoJ) expression is downregulated in low‐ and high‐grade human prostate cancer

Clusterin is overexpressed during tissue and cell involution and downregulated in proliferating cells. Its role in cell survival, cell death and neoplastic transformation remains debated. We studied the expression and distribution of clusterin mRNA and protein in human prostate carcinoma (CaP) specimens of different degrees of malignancy. Fresh CaP specimens were obtained from 25 patients subjected to long‐term androgen ablation before surgery. Clusterin expression was studied by Northern and Western analysis, in situ hybridization and immunohistochemistry, in comparison with Gas1 and histone H3 mRNA (markers of cell quiescence and S phase of the cell cycle, respectively). Clusterin is downregulated in CaP in comparison with matched benign controls. In low‐grade CaP, clusterin colocalized with Gas1 to the stromal compartment, and in some glands, the basal lamina was heavily stained. In high‐grade CaP clusterin stained the remnants of stromal matrix while histone H3 localized to cancer cells, which were very rarely clusterin positive. High clusterin expression was found in the branches of a nerve infiltrated by tumor. The periglandular clusterin expression found in low‐grade CaP could result from induction of quiescence and/or apoptosis of prostatic fibroblasts lining those glands in which tumor invasion is at an initial stage, involving basal lamina. In advanced CaP, the staining of the remnants of the extracellular matrix suggests a role for clusterin in the process of dismantling the stromal organization caused by cancer progression.

ROS, Cell Senescence, and Novel Molecular Mechanisms in Aging and Age-Related Diseases

The aging process worsens the human body functions at multiple levels, thus causing its gradual decrease to resist stress, damage, and disease. Besides changes in gene expression and metabolic control, the aging rate has been associated with the production of high levels of Reactive Oxygen Species (ROS) and/or Reactive Nitrosative Species (RNS). Specific increases of ROS level have been demonstrated as potentially critical for induction and maintenance of cell senescence process. Causal connection between ROS, aging, age-related pathologies, and cell senescence is studied intensely. Senescent cells have been proposed as a target for interventions to delay the aging and its related diseases or to improve the diseases treatment. Therapeutic interventions towards senescent cells might allow restoring the health and curing the diseases that share basal processes, rather than curing each disease in separate and symptomatic way. Here, we review observations on ROS ability of inducing cell senescence through novel mechanisms that underpin aging processes. Particular emphasis is addressed to the novel mechanisms of ROS involvement in epigenetic regulation of cell senescence and aging, with the aim to individuate specific pathways, which might promote healthy lifespan and improve aging.

Huwe1 ubiquitin ligase is essential to synchronize neuronal and glial differentiation in the developing cerebellum

We have generated a knockout mouse strain in which the gene coding for the ubiquitin ligase Huwe1 has been inactivated in cerebellar granule neuron precursors (CGNPs) and radial glia. These mice have a high rate of postnatal lethality and profound cerebellar abnormalities. The external granule layer of the cerebellum, which contains CGNPs, is expanded and displays aberrant proliferation and impaired differentiation of the progenitor cell population. The uncontrolled proliferation of the CGNPs is associated with accumulation of the N-Myc oncoprotein, a substrate of Huwe1, and con-sequent activation of the signaling events downstream to N-Myc. Furthermore, loss of Huwe1 in Bergmann glia leads to extensive disorganization of this cell population with layering aberrations, severe granule neuron migration defects, and persistence of ectopic clusters of granule neurons in the external granule layer. Our findings uncover an unexpected role for Huwe1 in regulating Berg-mann glia differentiation and indicate that this ubiquitin ligase orchestrates the programming of the neural progenitors that give rise to neurons and glia in the cerebellum.

Cell detachment and apoptosis induction of immortalized human prostate epithelial cells are associated with early accumulation of a 45 kDa nuclear isoform of clusterin

Clusterin, ubiquitously distributed in mammalians, was cloned and identified as the most potently induced gene during rat prostate involution following androgen deprivation. Also found to be involved in many other patho-physiological processes, its biological significance is still controversial, particularly with regard to apoptosis. We previously showed that transient over-expression of clusterin blocked cell cycle progression of simian-virus-40-immortalized human prostate epithelial cell lines PNT1A and PNT2. We show in the present study that the accumulation of an intracellular 45 kDa clusterin isoform was an early event closely associated with death of PNT1A cells caused by cell detachment followed by apoptosis induction (anoikis). Cell morphological changes, decreased proliferation rate and cell cycle arrest at G0/G1-S-phase checkpoint were all strictly associated with the production and early translocation to the nucleus of a 45 kDa clusterin isoform. Later, nuclear clusterin was found accumulated in detached cells and apoptotic bodies. These results suggest that a 45 kDa isoform of clusterin, when targeted to the nucleus, can decrease cell proliferation and promotes cell-detachment-induced apoptosis, suggesting a possible major role for clusterin as an anti-proliferative gene in human prostate epithelial cells.

Ca2+ depletion induces nuclear clusterin, a novel effector of apoptosis in immortalized human prostate cells

Ca 2+ depletion induces nuclear clusterin, a novel effector of apoptosis in immortalized human prostate cells

Anticancer Activity of Green Tea Polyphenols in Prostate Gland

Numerous evidences from prevention studies in humans, support the existence of an association between green tea polyphenols consumption and a reduced cancer risk. Prostate cancer is one of the most frequently diagnosed male neoplasia in the Western countries, which is in agreement with this gland being particularly vulnerable to oxidative stress processes, often associated with tumorigenesis. Tea polyphenols have been extensively studied in cell culture and animal models where they inhibited tumor onset and progression. Prostate cancer appears a suitable target for primary prevention care, since it grows slowly, before symptoms arise, thus offering a relatively long time period for therapeutic interventions. It is, in fact, usually diagnosed in men 50-year-old or older, when even a modest delay in progression of the disease could significantly improve the patients quality of life. Although epidemiological studies have not yet yielded conclusive results on the chemopreventive and anticancer effect of tea polyphenols, there is an increasing trend to employ these substances as conservative management for patients diagnosed with less advanced prostate cancer. Here, we intend to review the most recent observations relating tea polyphenols to human prostate cancer risk, in an attempt to outline better their potential employment for preventing prostate cancer.

Nuclear Translocation of a Clusterin Isoform Is Associated with Induction of Anoikis in SV40‐Immortalized Human Prostate Epithelial Cells

Abstract: Clusterin gene expression is potently induced in experimental models in which apoptosis is activated, such as rat prostate involution following castration. Nevertheless, its precise physiological role has not yet been established, and both anti‐apoptotic and pro‐apoptotic functions have been suggested for this gene. Clusterin expression level depends on cell proliferation state, and we recently showed that its over‐expression inhibited cell cycle progression of SV40‐immortalized human prostate epithelial cells PNT2 and PNT1a. Here we studied clusterin expression in PNT1a cells subjected to serum‐starvation with the aim of defining clusterin early molecular changes following apoptosis induction. Under serum‐starvation conditions, decreased growth rate, slow rounding‐up of cells, cell detachment, and formation of apoptotic bodies indicative of anoikis (detachment‐induced apoptosis) were preceded by significant downregulation of 70 kDa clusterin precursor and upregulation of 45–40 kDa isoforms. On the 8th day of serum‐free culturing, only the higher molecularweight protein‐band of about 45 kDa was clearly induced and accumulated in detached cells and apoptotic bodies in which PARP was activated. Anoikis was preceded by induction and transloction of a 45‐kDa clusterin isoform to the nucleus. Thus, nuclear targeting of a specific 45‐kDa isoform of clusterin appeared to be an early and specific molecular signal triggering anoikis‐death. Considering also that clusterin is downregulated during prostate cancer onset and progression, and that its upregulation has inhibited DNA synthesis and cell cycle progression of immortalized human prostate epithelial cells, we suggest that clusterin might be a new anti‐oncogene in the prostate.

MITOSTATIN, a putative tumor suppressor on chromosome 12q24.1, is downregulated in human bladder and breast cancer.

Allelic deletions on human chromosome 12q24 are frequently reported in a variety of malignant neoplasms, indicating the presence of a tumor suppressor gene(s) in this chromosomal region. However, no reasonable candidate has been identified so far. In this study, we report the cloning and functional characterization of a novel mitochondrial protein with tumor suppressor activity, henceforth designated MITOSTATIN. Human MITOSTATIN was found within a 3.2-kb transcript, which encoded a ∼62 kDa, ubiquitously expressed protein with little homology to any known protein. We found homozygous deletions and mutations of MITOSTATIN gene in ∼5 and ∼11% of various cancer-derived cells and solid tumors, respectively. When transiently overexpressed, MITOSTATIN inhibited colony formation, tumor cell growth and was proapoptotic, all features shared by established tumor suppressor genes. We discovered a specific link between MITOSTATIN overexpression and downregulation of Hsp27. Conversely, MITOSTATIN knockdown cells showed an increase in cell growth and cell survival rates. Finally, MITOSTATIN expression was significantly reduced in primary bladder and breast tumors, and its reduction was associated with advanced tumor stages. Our findings support the hypothesis that MITOSTATIN has many hallmarks of a classical tumor suppressor in solid tumors and may play an important role in cancer development and progression.

Mitostatin is down-regulated in human prostate cancer and suppresses the invasive phenotype of prostate cancer cells

MITOSTATIN, a novel putative tumor suppressor gene induced by decorin overexpression, is expressed in most normal human tissues but is markedly down-regulated in advanced stages of mammary and bladder carcinomas. Mitostatin negatively affects cell growth, induces cell death and regulates the expression and activation levels of Hsp27. In this study, we demonstrated that ectopic expression of Mitostatin in PC3, DU145, and LNCaP prostate cancer cells not only induced a significant reduction in cell growth, but also inhibited migration and invasion. Moreover, Mitostatin inhibited colony formation in soft-agar of PC3 and LNCaP cells as well as tumorigenicity of LNCaP cells in nude mice. Conversely, targeting endogenous Mitostatin by siRNA and anti-sense strategies in PC3 and DU145 prostate cancer cells enhanced the malignant phenotype in both cell lines. In agreement of these anti-oncogenic roles, we discovered that Mitostatin was absent in ∼35% (n = 124) of prostate tumor samples and its overall reduction was associated with advanced cancer stages. Collectively, our findings indicate that MITOSTATIN may acts as a tumor suppressor gene in prostate cancer and provide a novel cellular and molecular mechanism to be further exploited and deciphered in our understanding of prostate cancer progression.

Prevention of urinary bladder cancer in the FHIT knock-out mouse with Rofecoxib, a Cox-2 inhibitor.

OBJECTIVES Aberrant or increased expression of cyclooxygenase-2 (COX-2) has been implicated in the pathogenesis of many diseases, including cancer. However, the exact mechanism by which COX-2 may influence tumorigenesis has yet to be described. To investigate the chemopreventive role of a COX-2 inhibitor, rofecoxib, in the development of urinary bladder cancer, we studied the effect of this drug in heterozygous and nullizygous fragile histidine triad (FHIT) gene-deficient mice in a chemically induced carcinogenesis model. MATERIALS AND METHODS Two-hundred eight mice consisting of 50 FHIT +/+, 63 FHIT +/- and 95 FHIT -/-, were divided into five treatment groups and followed up for 15 weeks. Mice were treated with freshly prepared solution of 0.1% or 0.01% N-butyl-N-(-4-hydroxybutyl)-nitrosamine (BBN) in their drinking water and rofecoxib was administered in mouse chow at 150 parts per million concentration. Mice were sacrificed, and accurate histological analysis of the bladder was performed. RESULTS Rofecoxib treatment significantly reduced the incidence of preneoplastic lesions/bladder tumors (P = 0.016). Comparing the incidence of neoplastic lesions in mice treated with rofecoxib and BBN (22/56, 39.3%) and mice treated only with BBN (32/57, 56.1%), a protective role of rofecoxib on the BBN tumor induction has been observed (P = 0.024). A similar result (P = 0.002) has been reached observing the incidence of mild and moderate dysplasia in mice treated with a lower concentration of BBN (8/16, 50.0% vs. 20/24, 83.3%).Moreover, as previously observed, a significant increase in neoplastic lesions in the FHIT +/- and FHIT -/- vs. FHIT +/+ mice after BBN treatment has been observed (P = 0.003). CONCLUSIONS These findings suggest that rofecoxib provides a therapeutic defense against bladder carcinogenesis in our model and confirmed that the FHIT knock-out mouse is a suitable system to study in vivo bladder carcinogenesis.