Zimp7 and Zimp10, two novel PIAS-like proteins, function as androgen receptor coregulators

The androgen receptor (AR) plays a critical role in male sexual development and in normal and malignant prostate cell growth and survival. It has been shown that AR transcriptional activation is regulated through interactions with a variety of transcriptional co-regulators. The Protein Inhibitors of Activated STATs (PIAS) are transcriptional co-regulators, and have been shown to modulate AR-mediated transcription. In this brief, we summarize our recent studies on two novel PIAS-like proteins, Zimp7 and Zimp10. Particularly, we address the functional interactions between the AR and these two proteins, and potential mechanisms by which they regulate AR mediated transcription. In addition, we explore potential roles of Zimp10 in transcriptional regulation in vivo using a recent Zimp10 knockout mouse model. Taken together, our findings thus far suggest that Zimp7 and Zimp10 are functionally non-redundant and share unique characteristics that have not been described for the PIAS family. Further investigation into the functional roles of these two PIAS-like proteins may help to better understand prostate cancer progression, and yield possible new targets for therapeutic intervention

Prognostic implications of carboxyl-terminus of Hsc70 interacting protein and lysyl-oxidase expression in human breast cancer

This article has been made available through the Brunel Open Access Publishing Fund - Copyright @ 2010 Patani.Background: Ubiquitin modification of proteins influences cellular processes relevant to carcinogenesis. CHIP (carboxyl-terminus of Hsc70-interacting protein) is a chaperone-dependent E3 ubiquitin ligase, regulating the stability of heat shock protein 90 (HSP90) interacting proteins. CHIP is implicated in the modulation of estrogen receptor (ESR1) and Her-2/neu (ERBB2) stability. LOX (lysyl-oxidase) serves intracellular roles and catalyses the cross-linking of extracellular matrix (ECM) collagens and elastin. LOX expression is altered in human malignancies and their peri-tumoral stroma. However, paradoxical roles are reported. In this study, the level of mRNA expression of CHIP and LOX were assessed in normal and malignant breast tissue and correlated with clinico-pathological parameters. Materials and Methods: Breast cancer (BC) tissues (n = 127) and normal tissues (n = 33) underwent RNA extraction and reverse transcription; transcript levels were determined using real-time quantitative PCR and normalized against CK-19. Transcript levels were analyzed against TNM stage, nodal involvement, tumor grade and clinical outcome over a ten-year follow-up period. Results: CHIP expression decreased with increasing Nottingham Prognostic Index (NPI): NPI-1 vs. NPI-3 (12.2 vs. 0.2, P = 0.0264), NPI-2 vs. NPI-3 (3 vs. 0.2, P = 0.0275). CHIP expression decreased with increasing TNM stage: TNM-1 vs. TNM-2 (12 vs. 0, P = 0.0639), TNM-1 vs. TNM-2-4 (12 vs. 0, P = 0.0434). Lower transcript levels were associated with increasing tumor grade: grade 1 vs. grade 3 (17.7 vs. 0.3, P = 0.0266), grade 2 vs. grade 3 (5 vs. 0.3, P = 0.0454). The overall survival (OS) for tumors classified as ‘low-level expression’, was poorer than those with ‘high-level expression’ (118.1 vs. 152.3 months, P = 0.039). LOX expression decreased with increasing NPI: NPI-1 vs. NPI-2 (3 vs. 0, P = 0.0301) and TNM stage: TNM-1 = 3854639, TNM-2 = 908900, TNM-3 = 329, TNM-4 = 1.232 (P = NS). Conclusion: CHIP expression is associated with favorable prognostic parameters, including tumor grade, TNM stage and NPI. CHIP expression predicts OS. LOX expression is associated with improved NPI. In addition to their prognostic utility, mechanistic insights into tumor suppressor function may offer potential therapeutic strategies

PrbP modulates biofilm formation in Liberibacter crescens

In Liberibacter asiaticus, PrbP is a transcriptional regulatory protein involved in survival and persistence during host infection. Tolfenamic acid was previously found to inhibit interactions between PrbP and the promotor region of rplK, resulting in reduced survival of L. asiaticus in the citrus host. In this study, we performed transcriptome analyses to elucidate the PrbP regulon in L. crescens, as it is phylogenetically the closest related species to L. asiaticus that can be grown in laboratory conditions. Chemical inhibition of PrbP with tolfenamic acid revealed that PrbP is involved in the regulation of diverse cellular processes, including stress response, cell motility, cell cycle and biofilm formation. In vitro DNA binding and bacterial two-hybrid assays also suggested that PrbP is a global regulator of multiple transcription factors (RpoH, VisN, PleD, MucR, MocR and CtrA) at both transcriptional and/or post-transcriptional levels. Sub-lethal concentrations of tolfenamic acid significantly reduced the attachment of L. crescens during biofilm formation and decreased long-term persistence in biofilm structures. Overall, our findings show the importance of PrbP in regulating diverse biological processes through direct and indirect interactions with other transcriptional regulators in L. crescens.Fil: Pan, Lei. University of Florida. Department of Microbiology and Cell Science; Estados UnidosFil: Gardner, Christopher L.. University of Florida. Department of Microbiology and Cell Science; Estados UnidosFil: Beliakoff, Reagan. University of Florida. Department of Microbiology and Cell Science; Estados UnidosFil: Da Silva, Danilo. University of Florida. Department of Microbiology and Cell Science; Estados UnidosFil: Zuo, Ran. University of Florida. Department of Microbiology and Cell Science; Estados UnidosFil: Pagliai, Fernando A.. University of Florida. Department of Microbiology and Cell Science; Estados UnidosFil: Padgett Pagliai, Kaylie A.. University of Florida. Department of Microbiology and Cell Science; Estados UnidosFil: Merli, Marcelo Luciano. University of Florida. Department of Microbiology and Cell Science; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Bahadiroglu, Erol. University of Florida. Department of Microbiology and Cell Science; Estados UnidosFil: Gonzalez, Claudio F.. University of Florida. Department of Microbiology and Cell Science; Estados UnidosFil: Lorca, Graciela L.. University of Florida. Department of Microbiology and Cell Science; Estados Unido

The novel PIAS-like protein hZimp10 is a transcriptional co-activator of the p53 tumor suppressor

The tumor suppressor, p53, plays critical roles in the cell cycle progression, DNA repair and apoptosis. The PIAS proteins (protein inhibitor of activated STAT) were originally identified as inhibitors of the JAK-STAT pathway. Subsequently, crosstalk between the PIAS proteins and other signaling pathways has been shown to be involved in various cellular processes. Particularly, previous studies have demonstrated that PIAS proteins regulate p53-mediated transcription through sumoylation. hZimp10, also named zmiz1, is a novel PIAS-like protein and functions as a transcriptional co-activator. We recently identified p53 to be an hZimp10 interacting protein in the yeast two-hybrid screen. The interaction between p53 and hZimp10 was confirmed by GST pull-down and co-immunoprecipitation assays. Co-localization of p53 and hZimp10 proteins was also observed within cell nuclei by immunostaining. Moreover, we show that expression of exogenous hZimp10 enhances the transcriptional activity of p53 and knockdown of endogenous hZimp10 reduces the transcriptional activity of p53. Furthermore, using chromatin immunoprecipitation assays, we demonstrate that hZimp10 binds to p53 on the p21 promoter. Finally, p53-mediated transcription is significantly impaired in Zimp10 null embryonic fibroblasts. Taken together, these results provide the first line of evidence to demonstrate a role for Zimp10 in regulating p53 function

Heat shock protein-90 dampens and directs signaling stimulated by insulin-like growth factor-1 and insulin

AbstractHeat shock protein-90 (Hsp90) buffers cells from genetic mutations and environmental stresses. To test if this capability reflects a normal physiological function of Hsp90 to buffer cellular signals, the effects of Hsp90 inhibition were measured on activation of Akt. Inhibition of Hsp90 with geldanamycin amplified Akt phosphorylation induced by insulin-like growth factor-1 (IGF-1) or insulin, indicating that Hsp90 normally buffers these signals. Furthermore, with IGF-1 stimulation Hsp90 inhibition increased p38 activation, produced additive activation of p90RSK, and slightly increased the duration of ERK1/2 activation. Hsp90 dampened Akt signaling by facilitating phosphatase-mediated dephosphorylation of Akt. Thus, Hsp90 not only buffers the cellular effects of mutations and stresses, but also buffers the magnitude and duration of activation of proliferative and survival-promoting signaling responses

NVP-AUY922: a small molecule HSP90 inhibitor with potent antitumor activity in preclinical breast cancer models

INTRODUCTION:Heat shock protein 90 (HSP90) is a key component of a multichaperone complex involved in the post-translational folding of a large number of client proteins, many of which play essential roles in tumorigenesis. HSP90 has emerged in recent years as a promising new target for anticancer therapies.METHODS:The concentrations of the HSP90 inhibitor NVP-AUY922 required to reduce cell numbers by 50% (GI50 values) were established in a panel of breast cancer cell lines and patient-derived human breast tumors. To investigate the properties of the compound in vivo, the pharmacokinetic profile, antitumor effect, and dose regimen were established in a BT-474 breast cancer xenograft model. The effect on HSP90-p23 complexes, client protein degradation, and heat shock response was investigated in cell culture and breast cancer xenografts by immunohistochemistry, Western blot analysis, and immunoprecipitation.RESULTS:We show that the novel small molecule HSP90 inhibitor NVP-AUY922 potently inhibits the proliferation of human breast cancer cell lines with GI50 values in the range of 3 to 126 nM. NVP-AUY922 induced proliferative inhibition concurrent with HSP70 upregulation and client protein depletion � hallmarks of HSP90 inhibition. Intravenous acute administration of NVP-AUY922 to athymic mice (30 mg/kg) bearing subcutaneous BT-474 breast tumors resulted in drug levels in excess of 1,000 times the cellular GI50 value for about 2 days. Significant growth inhibition and good tolerability were observed when the compound was administered once per week. Therapeutic effects were concordant with changes in pharmacodynamic markers, including HSP90-p23 dissociation, decreases in ERBB2 and P-AKT, and increased HSP70 protein levels.CONCLUSION:NVP-AUY922 is a potent small molecule HSP90 inhibitor showing significant activity against breast cancer cells in cellular and in vivo settings. On the basis of its mechanism of action, preclinical activity profile, tolerability, and pharmaceutical properties, the compound recently has entered clinical phase I breast cancer trials

A promoting role of androgen receptor in androgen-sensitive and -insensitive prostate cancer cells

Although the vital role of the androgen receptor (AR) has been well demonstrated in primary prostate cancers, its role in the androgen-insensitive prostate cancers still remains unclear. Here, we used a small hairpin RNA approach to directly assess AR activity in prostate cancer cells. Reduction of AR expression in the two androgen-sensitive prostate cancer cell lines, LNCaP and LAPC4, significantly decreased AR-mediated transcription and cell growth. Intriguingly, in two androgen-insensitive prostate cell lines, LNCaP-C42B4 and CWR22Rv1, knockdown of AR expression showed a more pronounced effect on AR-induced transcription and cell growth than androgen depletion. Using cDNA microarrays, we also compared the transcriptional profiles induced by either androgen depletion or AR knockdown. Although a significant number of transcripts appear to be regulated by both androgen depletion and AR knockdown, we observed a subset of transcripts affected only by androgen depletion but not by AR knockdown, and vice versa. Finally, we demonstrated a direct role for AR in promoting tumor formation and growth in a xenograft model. Taken together, our results elucidate an important role for the AR in androgen-insensitive prostate cancer cells, and suggest that AR can be used as a therapeutic target for androgen-insensitive prostate cancers

Decreased Hsp90 expression in infiltrative lobular carcinoma: an immunohistochemical study

Background: Elevated Hsp90 expression has been documented in breast ductal carcinomas, whereas decreased Hsp90 expression has been reported in precursor lobular lesions. This study aims to assess Hsp90 expression in infiltrative lobular carcinomas of the breast. Methods: Tissue specimens were taken from 32 patients with infiltrative lobular carcinoma. Immunohistochemical assessment of Hsp90 was performed both in the lesion and the adjacent normal breast ducts and lobules; the latter serving as control. Concerning Hsp90 assessment: i) the percentage of positive cells and ii) the intensity were separately analyzed. Subsequently, the Allred score was adopted and calculated. The intensity was treated as a

Heat shock protein90 in lobular neoplasia of the breast

<p>Abstract</p> <p>Background</p> <p>Heat shock protein 90 (Hsp90) overexpression has been implicated in breast carcinogenesis, with putative prognostic and therapeutic implications. The purpose of this study is to evaluate the immunohistochemical expression of Hsp90 and to examine whether Hsp90 expression is associated with estrogen receptor alpha (ER-alpha) and beta (ER-beta) immunostaining in lobular neoplasia (LN) of the breast.</p> <p>Methods</p> <p>Tissue specimens were taken from 44 patients with LN. Immunohistochemical assessment of Hsp90, ER-alpha and ER-beta was performed both in the lesion and the adjacent normal breast ducts and lobules; the latter serving as control. As far as Hsp90 evaluation is concerned: i) the percentage of positive cells, and ii) the intensity was separately analyzed. Additionally, the Allred score was adopted and calculated. Accordingly, Allred score was separately evaluated for ER-alpha and ER-beta. The intensity was treated as an ordinal variable-score (0: negative, low: 1, moderate: 2, high: 3). Statistical analysis followed.</p> <p>Results</p> <p>Hsp90 immunoreactivity was mainly cytoplasmic in both the epithelial cells of normal breast (ducts and lobules) and LN. Some epithelial cells of LN also showed nuclear staining, but all the LN foci mainly disclosed a positive cytoplasmic immunoreaction for Hsp90. In addition, rare intralobular inflammatory cells showed a slight immunoreaction. The percentage of Hsp90 positive cells in the LN areas was equal to 67.1 ± 12.2%, whereas the respective percentage in the normal adjacent breast tissue was 69.1 ± 11.6%; the difference was not statistically significant. The intensity score of Hsp90 staining was 1.82 ± 0.72 in LN foci, while in the normal adjacent tissue the intensity score was 2.14 ± 0.64. This difference was statistically significant (p = 0.029, Wilcoxon matched-pairs signed-ranks test). The Hsp90 Allred score was 6.46 ± 1.14 in the LN foci, significantly lower than in the normal adjacent tissue (6.91 ± 0.92, p = 0.049, Wilcoxon matched-pairs signed-ranks test). Within the LN foci, the Hsp90 Allred score was neither associated with ER-alpha, nor with ER-beta percentage.</p> <p>Conclusion</p> <p>Hsp90 was lower in LN foci both at the level of intensity and Allred score, a finding contrary to what might have been expected, given that high Hsp90 expression is detected in invasive breast carcinomas. Hsp90 deregulation does not seem to be a major event in LN pathogenesis.</p