Biomedical subjects

Itzhak D Goldberg

Publications and source records attributed to Itzhak D Goldberg.

15 recordsLinked to original sources

PubMed2006

Expression of neuronal protein synuclein gamma gene as a novel marker for breast cancer prognosis.

Synucleins are emerging as central players in the fundamental neural processes and in the formation of pathologically insoluble deposits characteristic of neurodegenerative diseases. However, synuclein gamma (SNCG), previously identified as a breast cancer specific gene (BCSG1), is also highly expressed in breast carcinomas, but not expressed in normal or benign breast tissues. We analyzed SNCG gene expression in 93 clinical breast specimens and associated it with clinical outcome. Overall SNCG mRNA expression was detectable in 36% breast cancers. However, 81% of stage III/IV breast cancers were positive for SNCG expression, while only 15% of stage I/II breast cancers were positive for SNCG expression. In contrast, SNCG was undetectable in benign breast lesions. Expression of SNCG in the primary tumor also significantly associated with lymph node involvement and metastasis. There was no significant correlation between SNCG gene expression and age, menstruation, and status of ER, PR, PCNA, and HER-2. Patients whose tumors expressed SNCG had a significantly shorter DFS and a high probability of death when compared with those whose tumors did not express SNCG. The hazard ratio of metastasis or recurrence according to the SNCG status was 4.515 (95% CI, 1,188-17.154; P = 0.027). Cox multivariate analysis showed that SNCG had independent prognostic significance above and beyond conventional variables. This study suggests that the expression of SNCG is an independent predictive marker for recurrence and metastasis in breast cancer progression. SNCG is expected to be a useful marker for breast cancer progression and a potential target for breast cancer treatment.

Adult↗

PubMed2006

Identification of genes that modulate sensitivity of U373MG glioblastoma cells to cis-platinum.

Scatter factor (hepatocyte growth factor) and its receptor c-Met are increasingly expressed during progression from low-grade to high-grade gliomas. Scatter factor/c-Met signaling induces glioma cell motility, invasion, angiogenesis and resistance to DNA-damaging agents. The latter is relevant to the understanding of the resistance of human gliomas to chemotherapy and radiotherapy. The goal of this study was to identify a set of genes that may contribute to scatter factor-mediated protection of U373MG cells against cis-platinum, a DNA cross-linking agent. We used DNA microarray assays, confirmatory semiquantitative reverse transcription-polymerase chain reaction analysis and functional assays to identify genes involved in the scatter factor-induced resistance of U373MG to cis-platinum. We identified a group of genes that are overexpressed in cells treated with scatter factor plus cis-platinum relative to cells treated with cis-platinum alone and confirmed some of these gene expression alterations by reverse transcription-polymerase chain reaction. Inhibiting the expression of three of these genes--polycystic kidney disease 1, amplified in breast cancer 1 and DEAD/H box helicase 21--using small interfering RNAs reduced survival of cis-platinum-treated cells and partially reversed the scatter factor protection against cis-platinum. Dominant-negative Akt and IkappaB super-repressor expression vectors inhibited the scatter factor protection, and abrogated the ability of scatter factor to alter the expression of DEAD/H box helicase 21 and polycystin (PKD1) within the context of cis-platinum exposure. The Akt and nuclear factor-kappaB inhibitors had no effect on amplified in breast cancer 1 expression. These studies implicate DEAD/H box helicase 21, polycystin (PKD1) and amplified in breast cancer 1 as novel transcription-dependent regulators of scatter factor-mediated glioma cell protection against cytotoxic death, and identify other potential regulators for future study.

Antineoplastic Agents↗

PubMed2005

Structural determinants of the BRCA1 : estrogen receptor interaction.

Previously, we showed that the BRCA1 protein interacts directly and functionally with estrogen receptor-alpha (ER-alpha), resulting in the inhibition of estradiol (E2)-stimulated ER-alpha transcriptional activity. The interaction sites were mapped to the N-terminus of BRCA1 (within amino acids (aa) 1-302) and the ligand-binding domain/activation function-2 (LBD/AF-2) region (within aa 282-420) of ER-alpha. In this study, we have further characterized the structure/function relationship for the BRCA1 : ER-alpha interaction. We found that the N-terminal RING domain (aa 20-64) is not required for the BRCA1 : ER-alpha interaction. We identified two separate contact points for ER-alpha, one within aa 1-100 and the other within aa 100-200 of BRCA1; and we showed that each of these BRCA1 peptides interacts with BRCA1 in vitro and in vivo. By using different fragments of the BRCA1 N-terminus, we found that aa 67-100 and 101-133 are required for the interaction with ER-alpha, but that aa 1-67 and 134-302 are dispensible. Previously, we showed that BRCA1 aa 1-302 does not inhibit E2-stimulated ER-alpha transcriptional activity but does bind to ER-alpha and acts as a dominant negative inhibitor of the full-length BRCA1 protein. Somewhat surprisingly, we found that BRCA1 aa 1-100 and BRCA1 aa 101-200 (but not aa 201-300) each inhibited ER-alpha activity, although not as efficiently as full-length BRCA1. Mutations within an HIV Rev-like nuclear export signal that resembles a nuclear receptor corepressor motif (aa 86-95) impaired the ability of both truncated (aa 1-100) and full-length (aa 1-1863) BRCA1 proteins to interact with and/or repress ER-alpha activity. Based on these findings, a partial BRCA1 : ER-alpha three-dimensional structure is proposed. The implications of these findings for understanding the BRCA1 : ER-alpha interaction are discussed.

Amino Acid Sequence↗

PubMed2005

Role of NF-kappaB signaling in hepatocyte growth factor/scatter factor-mediated cell protection.

The cytokine scatter factor/hepatocyte growth factor (HGF/SF) protects epithelial, carcinoma, and other cell types against cytotoxicity and apoptosis induced by DNA-damaging agents such as ionizing radiation and adriamycin (ADR, a topoisomerase IIalpha inhibitor). We investigated the role of nuclear factor kappa B (NF-kappaB) signaling in HGF/SF-mediated protection of human prostate cancer (DU-145) and Madin-Darby canine kidney (MDCK) epithelial cells against ADR. HGF/SF caused the rapid nuclear translocation of the p65 (RelA) subunit of NF-kappaB associated with the transient loss of the inhibitory subunit IkappaB-alpha. Exposure to HGF/SF caused the activation of an NF-kappaB luciferase reporter that was blocked or attenuated by the expression of a mutant 'super-repressor' IkappaB-alpha. Electrophoretic mobility shift assay supershift assays revealed that HGF/SF treatment induced the transient binding of various NF-kappaB family proteins (p65, p50, c-Rel, and RelB) with radiolabeled NF-kappaB-binding oligonucleotides. The HGF/SF-mediated protection of DU-145 and MDCK cells against ADR (demonstrated using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays) was abrogated by the IkappaB-alpha super-repressor. The ability of HGF/SF to activate NF-kappaB signaling was dependent on c-Akt --> Pak1 (p21-associated kinase-1) signaling (with Pak1 downstream of c-Akt) and was inhibited by the tumor suppressor PTEN (phosphatase and tensin homolog). Inhibitors of phosphatidylinositol-3'-kinase and Src family kinases significantly inhibited HGF/SF-mediated activation of NF-kappaB, while inhibitors of MEK, protein kinase C, and p70 S6 kinase had a modest effect or no effect on NF-kappaB activity. HGF/SF induced the expression of several known NF-kappaB target genes (cIAP-1 (cellular inhibitor of apoptosis-1), cIAP-2, and TRAF-2 (TNF receptor-associated factor-2)) in an NF-kappaB-dependent manner; HGF/SF blocked the inhibition of expression of these genes by ADR. Experimental manipulation of expression of these genes suggests that they (particularly TRAF-2 and cIAP-2) contribute to the protection against ADR by HGF/SF. These findings suggest that HGF/SF activates NF-kappaB through a c-Akt --> Pak1 signaling pathway that is also dependent on Src, and that NF-kappaB contributes to HGF/SF-mediated protection against ADR.

Active Transport, Cell Nucleus↗

PubMed2004

BRCA1 induces antioxidant gene expression and resistance to oxidative stress.

Mutations of the breast cancer susceptibility gene 1 (BRCA1), a tumor suppressor, confer an increased risk for breast, ovarian, and prostate cancers. To investigate the function of the BRCA1 gene, we performed DNA microarray and confirmatory reverse transcription-PCR analyses to identify BRCA1-regulated gene expression changes. We found that BRCA1 up-regulates the expression of multiple genes involved in the cytoprotective antioxidant response, including glutathione S-transferases, oxidoreductases, and other antioxidant genes. Consistent with these findings, BRCA1 overexpression conferred resistance while BRCA1 deficiency conferred sensitivity to several different oxidizing agents (hydrogen peroxide and paraquat). In addition, in the setting of oxidative stress (due to hydrogen peroxide), BRCA1 shifted the cellular redox balance to a higher ratio of reduced to oxidized glutathione. Finally, BRCA1 stimulated antioxidant response element-driven transcriptional activity and enhanced the activity of the antioxidant response transcription factor nuclear factor erythroid-derived 2 like 2 [also called NRF2 (NFE2L2)]. The ability of BRCA1 to stimulate antioxidant response element-dependent transcription and to protect cells against oxidative stress was attenuated by inhibition of nuclear factor erythroid-derived 2 like 2. These findings suggest a novel function for BRCA1, i.e., to protect cells against oxidative stress. This function would be consistent with the postulated role of BRCA1 as a caretaker gene in preserving genomic integrity.

Antioxidants↗

PubMed2004

Gamma synuclein, a novel heat-shock protein-associated chaperone, stimulates ligand-dependent estrogen receptor alpha signaling and mammary tumorigenesis.

Synucleins are emerging as central players in the formation of pathologically insoluble deposits characteristic of neurodegenerative diseases. gamma synuclein (SNCG), previously identified as a breast cancer-specific gene (BCSG1), is also highly associated with breast or ovarian cancer progression. However, the molecular targets of SNCG aberrant expression in breast cancer have not been identified. Here, we demonstrated a chaperone activity of SNCG in the heat-shock protein (Hsp)-based multiprotein chaperone complex for stimulation of estrogen receptor (ER)-alpha signaling. As an ER-alpha-associated chaperone, SNCG participated in Hsp-ER-alpha complex, enhanced the high-affinity ligand-binding capacity of ER-alpha, and stimulated ligand-dependent activation of ER-alpha. The SNCG-mediated stimulation of ER-alpha transcriptional activity is consistent with its stimulation of mammary tumorigenesis in response to estrogen. These data indicate that SNCG is a new chaperone protein in the Hsp-based multiprotein chaperone complex for stimulation of ligand-dependent ER-alpha signaling and thus stimulates hormone-responsive mammary tumorigenesis.

Breast Neoplasms↗

PubMed2003

Induction of mammary gland differentiation in transgenic mice by the fatty acid-binding protein MRG.

A mammary-derived growth inhibitor-related gene (MRG) was previously identified and characterized. MRG induces differentiation of mammary epithelial cells in vitro and its expression is associated with mammary differentiation. To further define the role of MRG on mammary gland differentiation, a MRG transgenic mice model under the control of mouse mammary tumor virus promoter was established and the effect of MRG on mammary gland differentiation was investigated at histological and molecular levels. Expression of endogenous mouse MRG gene was significantly increased from the non-differentiated gland of control virgin mice to the functionally differentiated gland of pregnant control mice. Whole mount analyses demonstrated that ductal development was not affected by MRG transgene expression. While there was no lobuloalveolar structure in control virgin mice, expression of MRG transgene in the mammary gland resulted in the development of lobuloalveolar-like structure, which mimics the gland from early pregnancy. Consistent with the morphological change, expression of MRG also increased milk protein beta-casein expression in the gland. To study the mechanism of MRG-induced mammary differentiation, we investigated the Stat5 activation in the glands from the transgenic mouse versus virgin control mouse. While activated Stat5 was expressed at the minimal level in the non-differentiated control virgin gland, a significant Stat5 phosphorylation was observed in the virgin transgenic gland. Our data indicate that MRG is a mediator of the differentiating effects of pregnancy on breast epithelium, and overexpression of MRG in young nulliparous mice can induce differentiation.

Animals↗

PubMed2003

Stimulation of estrogen receptor signaling by gamma synuclein.

Synucleins are emerging as central player in the fundamental neural processes and in the formation of pathologically insoluble deposits characteristic of Alzheimer's disease and Parkinson's disease. However, gamma Synuclein (SNCG) is also highly associated with breast cancer and ovarian cancer progression. Whereas most studies of this group of proteins have been directed to the elucidation of their role in the formation of depositions in brain tissue, the normal cellular function of this highly conserved synuclein family remains largely unknown. A notable finding in this study is that SNCG, identified previously as a breast cancer-specific gene 1, strongly stimulated the ligand-dependent transcriptional activity of estrogen receptor-alpha (ER-alpha) in breast cancer cells. Augmentation of SNCG expression stimulated transcriptional activity of ER-alpha, whereas compromising endogenous SNCG expression suppressed ER-alpha signaling. The SNCG-stimulated ER-alpha signaling was demonstrated in three different cell systems including ER-alpha-positive and SNCG-negative MCF-7 cells, ER-alpha-positive and SNCG-positive T47D cells, and SNCG-negative and ER-alpha-negative MDA-MB-435 cells. The SNCG-mediated stimulation of ER-alpha transcriptional activity is consistent with its stimulation of the ligand-dependent cell growth. Whereas overexpression of SNCG stimulated the ligand-dependent cell proliferation, suppression of endogenous SNCG expression significantly inhibited cell growth in response to estrogen. The stimulatory effect of SNCG on ERalpha-regulated gene expression and cell growth can be effectively inhibited by antiestrogens. These data indicate that SNCG is required for efficient ER-alpha signaling and, thus, stimulated hormone-responsive mammary tumors.

Breast Neoplasms↗

PubMed2003

Pretreatment of indole-3-carbinol augments TRAIL-induced apoptosis in a prostate cancer cell line, LNCaP.

Prostate cancer is one of the most common cancers in men and is the second leading cause of cancer-related deaths in the USA. Many anti-tumor agents against prostate cancer cells have been developed, but their unacceptable systemic toxicity to normal tissues frequently limits their usage in clinics. Several previous studies have demonstrated that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can induce cell death in a variety of transformed cells including prostate cancer cells, but not normal cells. Indole-3-carbinol (I3C), a phytochemical that is produced in fruits and vegetables, may play an important role in the prevention of many types of cancer, including hormone-related ones such as breast and prostate cancer. In this study, we examined the potential sensitizing effects of I3C on TRAIL-mediated apoptosis in a prostate cancer cell line, LNCaP. When LNCaP cells were incubated with I3C (either 30 or 90 microM) for 24 h and then treated with TRAIL (100 ng/ml), enhanced TRAIL-mediated apoptosis was observed. The enhanced apoptosis measured by poly(ADP-ribose) polymerase and caspase 3 cleavage. We also observed that loss of cell viability after treatment with I3C/TRAIL is greater compared with I3C and TRAIL alone. To determine the molecular mechanisms involved in the enhanced apoptosis, we examined the expression of two TRAIL death receptors (DR4 and DR5) and two TRAIL decoy receptors (DcR1 and DcR2). We found that treatment with I3C induced DR4 and DR5 expression at both transcriptional and translational levels. These findings suggest that I3C may be an effective sensitizer of TRAIL treatment against TRAIL-resistant prostate cancer cell lines such as LNCaP.

Antioxidants↗

PubMed2003

Role of BRCA1 in heat shock response.

The heat shock response is an evolutionarily conserved response to heat and other stresses that promotes the maintenance of key metabolic functions and cell survival. We report that exposure of human prostate (DU-145) and breast (MCF-7) cancer cells to heat (42 degrees C) caused a rapid disappearance of the breast cancer susceptibility gene-1 (BRCA1) protein, starting at approximately 1 h after the onset of heating and slightly lagging behind the increase in heat shock protein 70 (HSP70) levels. The heat-induced loss of BRCA1 occurred at the protein level, since: (1) BRCA1 mRNA expression was unaffected; and (2) the BRCA1 protein loss was also observed in DU-145 cells that expressed exogenous wild-type BRCA1 (wtBRCA1). In addition to heat regulation of BRCA1 protein levels, we also found that BRCA1 could modulate the heat shock response. Thus, wtBRCA1 overexpressing DU-145 cell clones showed significantly decreased sensitivity to heat-induced cytotoxicity; and Brca1 mutant mouse embryo fibroblasts showed increased sensitivity to heat. The DU-145 wtBRCA1 clones also showed increased expression of the small heat shock protein HSP27; and reporter assays revealed that wtBRCA1 stimulated a two to four-fold increase in HSP27 promoter activity, consistent with its ability to upregulate HSP27 mRNA and protein levels. In studies using epitope-tagged truncated BRCA1 proteins, the ability to stimulate the HSP27 promoter and to mediate heat-induced degradation required the amino-terminus but not the carboxyl-terminus of BRCA1. Although the heat-induced loss of BRCA1 appeared to be due to protein degradation, various protein metabolic agents (or combinations) failed to block this event, including: MG132 (a 26S proteasomal inhibitor), N-acetyl-leucyl-leucyl-norleucinal (a calpain inhibitor), z-VAD-fmk (a pan-caspase inhibitor), and ammonium chloride and chloroquine (which stabilize lysosomes). These findings suggest that in addition to its other functions, BRCA1 may participate in mammalian heat shock response pathways.

BRCA1 Protein↗

PubMed2003

BRCA1 gene in breast cancer.

The BRCA1 gene was identified and cloned in 1994 based its linkage to early onset breast cancer and breast-ovarian cancer syndromes in women. While inherited mutations of BRCA1 are responsible for about 40-45% of hereditary breast cancers, these mutations account for only 2-3% of all breast cancers, since the BRCA1 gene is rarely mutated in sporadic breast cancers. However, BRCA1 expression is frequently reduced or absent in sporadic cancers, suggesting a much wider role in mammary carcinogenesis. Since BRCA1 was cloned in 1994, its molecular function has been the subject of intense investigation. These studies have revealed multiple functions of the BRCA1 that may contribute to its tumor suppressor activity, including roles in: cell cycle progression, several highly specialized DNA repair processes, DNA damage-responsive cell cycle check-points, regulation of a set of specific transcriptional pathways, and apoptosis. Many of these functions are linked to protein:protein interactions involving different portions of the 1,863 amino acid (aa) BRCA1 protein. BRCA1 functions in cell cycle progression and the DNA damage response appear to be regulated by distinct and specific phosphorylation events, but the molecular pathways activated by these phosphorylations are only beginning to be unraveled. In addition, the reason that BRCA1 mutation carriers develop specific tumor types (breast and ovarian cancers in women and possibly prostate cancers in men) is not clearly understood. Elucidation of the precise molecular functions of the BRCA1 gene product will greatly enhance our understanding of the pathogenesis of hereditary as well as sporadic mammary carcinogenesis.

Amino Acid Sequence↗

PubMed2003

BRCA1 in hormone-responsive cancers.

Mutations of the breast cancer susceptibility gene BRCA1 are linked to hereditary early onset breast and breast-ovarian cancer syndromes. These mutations confer an increased risk for other hormone-dependent cancers, including those of the uterus, cervix and prostate. BRCA1 expression is decreased or absent in a significant proportion of sporadic breast and ovarian cancers, suggesting a wider role in these tumor types. Multiple functions for BRCA1 have been identified, including roles in DNA repair, cell-cycle progression and apoptosis. These functions are consistent with a tumor suppressor activity, but they do not explain why BRCA1 mutation carriers develop hormone-responsive cancer types. Recent studies indicate that BRCA1 interacts with and regulates the activity of estrogen receptor alpha (ER alpha) and the androgen receptor. Its expression is regulated by carcinogens and anticarcinogens that modulate ER alpha signaling, suggesting a molecular linkage between BRCA1 and hormone-responsive cancers.

Aged↗

PubMed2003

BRCA1 inhibition of telomerase activity in cultured cells.

Telomerase, an enzyme that maintains telomere length, plays major roles in cellular immortalization and cancer progression. We found that an exogenous BRCA1 gene strongly inhibited telomerase enzymatic activity in human prostate and breast cancer cell lines and caused telomere shortening in cell lines expressing wild-type BRCA1 (wtBRCA1) but not a tumor-associated mutant BRCA1 (T300G). wtBRCA1 inhibited the expression of the catalytic subunit (telomerase reverse transcriptase [TERT]) but had no effect on the expression of a subset of other components of the telomerase holoenzyme or on the expression of c-Myc, a transcriptional activator of TERT. However, endogenous BRCA1 associated and partially colocalized with c-Myc; exogenous wtBRCA1 strongly suppressed TERT promoter activity in various cell lines. The TERT inhibition was due, in part, to suppression of c-Myc E-box-mediated transcriptional activity. Suppression of TERT promoter and c-Myc activity required the amino terminus of BRCA1 but not the carboxyl terminus. Finally, endogenous BRCA1 and c-Myc were detected on transfected mouse and human TERT promoter segments in vivo. We postulate that inhibition of telomerase may contribute to the BRCA1 tumor suppressor activity.

Animals↗

PubMed2002

Complex roles of tissue inhibitors of metalloproteinases in cancer.

Matrix metalloproteinases (MMPs) is tightly associated with extracellular matrix (ECM) turnover, which plays a very active role in tumor invasion and metastasis. Tissue inhibitors of metalloproteinases (TIMPs) plays a critical role in the homeostasis of ECM by regulating the activity of MMPs. TIMPs are well-known for their ability to inhibit MMP activity thereby inhibiting tumor growth and metastasis. However, many evidences suggest that TIMPs are multifunctional proteins, which regulate cell proliferation, apoptosis, proMMP-2 activation, and angiogenesis. These effects may be through MMP-dependent or MMP-independent pathways. Recent data indicate that TIMPs have many paradoxical roles in tumorigenesis. In particular, both inhibitory effect and stimulatory effect on tumorigenesis have been demonstrated in many animal models in which TIMPs were overexpressed in cancer cells or in mice. Elevated TIMP levels are reported in association with cancer progression and identified as poor prognostic indicators in several human tumor types. Herein, we review the complex roles of TIMPs in cancer growth and metastasis.

Animals↗

PubMed2002

p300 Modulates the BRCA1 inhibition of estrogen receptor activity.

We previously reported that expression of the breast cancer susceptibility gene BRCA1 strongly inhibits the transcriptional activity of the estrogen receptor (ER-alpha) in human breast and prostate cancer cell lines but only weakly inhibits ER-alpha activity in cervical cancer cells (S. Fan et al., Science (Wash. DC), 284: 1354-1356, 1999). We now report that the ability of BRCA1 to repress ER-alpha activity correlates with its ability to induce down-regulation of the cellular levels of the transcriptional coactivator p300 in breast and prostate, but not in cervical cancer cells. On the other hand, BRCA1 failed to alter the expression of the CREB binding protein (CBP), the structural and functional homologue of p300, in any of these cell types. Ectopic expression of either p300 or CBP "rescued" (i.e., reversed) the BRCA1 inhibition of ER-alpha activity, whereas two other nuclear receptor coactivators, the p300/CBP-associated factor (PCAF) and the glucocorticoid receptor-interacting protein-1 (GRIP1), failed to rescue the ER-alpha activity. The rescue function mapped to the cysteine-histidine rich domain CH3, a region of p300/CBP that we found to interact directly with the conserved COOH-terminal activation domain (AF-2) of ER-alpha. p300 and ER-alpha were also found to interact in vivo and to colocalize within the nucleus in breast cancer cells. These findings suggest that the cofactors p300 and CBP modulate the ability of the BRCA1 protein to inhibit ER-alpha signaling. They further suggest that the BRCA1 inhibition of ER-alpha activity may be attributable, at least in part, to the down-regulation of p300.

BRCA1 Protein↗