Biomedical subjects

Deodutta Roy

Publications and source records attributed to Deodutta Roy.

11 recordsLinked to original sources

PubMed2007

Signature of mitochondria of steroidal hormones-dependent normal and cancer cells: potential molecular targets for cancer therapy.

The cross-talk between the cell nucleus and mitochondria appears to control hormone-induced signaling involved in the apoptosis, proliferation, and differentiation of both normal and malignant cells. Evaluation of the defects in genetics and physiology of human endocrine diseases, such as cancer, may manifest as a result of mitochondrial physiologic and metabolic compensation of genetic defects. Steroidal agents control biogenesis and maintenance of mitochondria through the crosstalk between nuclear and mitochondrial genomes. The regulation of mitochondrial transcription by steroidal hormones, presumably occurring through pathways similar to those that take place in the nucleus, opens a new way to better understand steroid hormone and vitamin action at the cellular level. In addition to the steroid hormone receptors, estrogen generated mitochondrial oxidants together with an estrogen-driven increase in epithelial cell proliferation have been shown to participate in the initiation and promotion of the neoplastic lesions in estrogen-sensitive tissues. Mitochondria generation of ROS appears to transduce signals to the nucleus for the activation of transcription factors involved in the cell cycle progression of estrogen-dependent cancer cells. Therefore, an in-depth analysis of such redox regulatory mechanisms is pertinent to the development of novel drugs and gene therapy strategies for the treatment of steroid hormone-dependent diseases related to mitochondrial disorders including cancer.

Estrogen Receptor Modulators↗

PubMed2006

Estrogen exerts a spatial and temporal influence on reactive oxygen species generation that precedes calcium uptake in high-capacity mitochondria: implications for rapid nongenomic signaling of cell growth.

Novel findings that emerged from this study underscore the fact that the dynamic nature of mitochondria leads to functional heterogeneity of [Ca(2+)](mito) with respect to estrogen actions in MCF7 cells. We show that estrogen exposure to cells increased [Ca(2+)](mito) in a high-calcium capacity mitochondrial population but not in low-calcium capacity mitochondria. Physiological concentrations of 17beta-estradiol (E2) modulated Ca(2+)(mito) uptake within 90 s. Interestingly, this calcium response lagged behind the induction of mitochondrial reactive oxygen species (mtROS). The rapid induction of Ca(2+)(mito) in response to E2 and its inhibition by mitochondrial blockers suggest that mitochondria are early nongenomic targets of E2. This suggests that a subpopulation of mitochondria is recruited to respond to new metabolic requirements required by estrogen triggers or, as in this case, E2-induced Ca(2+)(mito) and/or mtROS promotes oxidative signaling without involving nuclear estrogen receptor signaling. Although the early E2-induced Ca(2+) did not alter the expression of genes involved in calcium signaling pathways, an intracellular calcium chelator BAPTA-AM and the Ca(2+)(mito) uniporter blocker ruthenium red prevented E2-induced cell growth. We have shown recently that E2-mediated ROS production controls the promoter activity of cyclin D1 by post-translational modification of calcium sensitive transcription factor CREB. The findings of this study offer a new paradigm that rapid E2-induced changes in mtROS and Ca(2+)(mito) are involved in cell cycle progression presumably through the control of early cell cycle genes. Targeting mitochondria to disrupt communication between mitochondria and ROS/Ca(2+) signaling pathways may provide the basis for a novel anticancer strategy for the treatment of estrogen-dependent breast cancer.

Breast Neoplasms↗

PubMed2006

Levels of IL-1 beta control stimulatory/inhibitory growth of cancer cells.

Different cellular signaling pathways operate in response to varying levels of IL-1 beta leading to genotoxic damage, cell apoptosis or cell growth. At high levels of IL-1 beta, cells receiving genotoxic insults engage apoptotic pathways. The IL-1 beta over expressing stable MCF7 cell secreting high level of IL-1 beta peptides undergo cell apoptosis. Cotreatment with an inhibitor of IL-1 beta and TNF-alpha synthesis prevented stilbene estrogen-induced lesions. In addition to direct effect of 17 beta-estradiol (E2) on mitochondria and redox cycling of catechol estrogens, E2-induced overexpression of IL-1 beta can produce an increase in the level of ROS. Our recent data showed that MCF7 cell growth and cyclin D1 expression are suppressed by antioxidants and mitochondrial blockers. Stably IL-1 beta transfected cells secreting moderate level of IL-1 beta peptides stimulated the clonal expansion of MCF7 cells. These studies support that in addition to ovarian estrogens, mitogenic signals may also come from TNF-alpha and IL-1 beta-generated O2*- and hydrogen peroxide. Further validation of this concept that the concentrations of the peptide interleukin-1 beta within the cells determine its stimulatory or inhibitory signals regulating the growth of estrogen-dependent tumors might result in novel preventive strategies.

Animals↗

PubMed2006

Development of a self-proliferating Leydig cell line: a hyper-sensitive E-screening model.

The mechanisms of estrogenic endocrine disruption on the male reproductive tract are poorly understood. In order to examine estrogenic properties of xenobiotic chemicals on male tissues, we have developed a mouse Leydig cell line (TM3-SF) that self-proliferates under serum-free conditions. This cell line was derived from ATCC's cell line, TM3. The development of TM3-SF was accomplished over a 4-month period by a progressive serum starvation of the original TM3 cells. The newly established cell line was maintained under serum-free conditions for 20 passages prior to testing. Sensitivity of the TM3-SF cells to estrogens was assayed by cell proliferation studies. A total of four compounds, diethylstilbestrol (DES), 17beta-estradiol, 17alpha-estradiol, and Bis-phenol A, were tested. Significant increases in cell proliferation occurred at various concentrations ranging from 1 pg/ml to 100 ng/ml for all four compounds. The order of potency observed was DES > Bis-phenol A > 17beta-estradiol and > 17alpha-estradiol. In addition, we investigated the mechanism for the self-proliferative properties of TM3-SF. The results of these trials indicate that either inhibin or activin is a primary growth factor for this cell line as a 50% inhibition of growth was noted when cell cultures were exposed to the anti-betaa subunit of inhibin/activin. Furthermore, the addition of the anti-betaa subunit of inhibin/activin blocked the DES-induced proliferation of TM3-SF. We conclude that the growth of TM3-SF cells is estrogen sensitive and that either inhibin or activin is involved in the self-regulation of growth.

Activins↗

PubMed2005

Estrogen-induced G1/S transition of G0-arrested estrogen-dependent breast cancer cells is regulated by mitochondrial oxidant signaling.

We previously reported that 17-beta-estradiol (E2)-induced mitochondrial reactive oxygen species (mtROS) act as signaling molecules. The purpose of this study was to investigate the effects of E2-induced mtROS on cell cycle progression. E2-induced cell growth was reduced by antioxidants N-acetyl-L-cysteine (NAC), catalase, and the glutathione peroxidase mimic ebselen. Flow cytometry showed that mitochondrial blockers of protein synthesis (chloramphenicol), transcription and replication (ethidium bromide), and function (rotenone, rhodamine 6G) blocked E2-induced G1 to S transition. Reduction of E2-induced DNA synthesis in the presence of mitochondrial blockers occurred without influencing the level of ATP. Additionally, the mitochondrial blockers inhibited the E2-induced expression of early cell cycle genes such as cyclins D1, D3, E1, E2, and B2. NAC or rotenone reduced E2-induced cyclin D1 expression. Furthermore, E2-induced binding of AP-1 and CREB to the TRE and CRE response sequences, respectively, in the promoter of cyclin D1 was inhibited by NAC or rotenone. In addition, E2-induced expression of PCNA, PRC1, and bcl-2 were inhibited by mitochondrial blockers. These data indicate that E2-induced mtROS are involved in the regulation of early G1-phase progression. Since neither antioxidants nor mitochondrial blockers used in this study are reported to bind the estrogen receptor (ER), our findings suggest that E2-induced mtROS modulates G1 to S transition and some of the early G1 genes through a nongenomic, ER-independent signaling pathway. Thus, our results suggest (1) a new paradigm that estrogen-induced mitochondrial oxidants control the early stage of cell cycle progression and (2) provide the basis for the discovery of novel antioxidant-based drugs or antioxidant gene therapies for the prevention and treatment of estrogen-dependent breast cancer.

Base Sequence↗

PubMed2005

Estrogen-induced mitochondrial reactive oxygen species as signal-transducing messengers.

We report here evidence in support of the role of 17beta-estradiol- (E2-) induced mitochondrial (mt) reactive oxygen species (ROS) as signal-transducing messengers. On the basis of monitoring the oxidation of 2',7'-dichlorofluorescin by spectrofluorometry, flow cytometry, and confocal microscopy, we have identified that exposure of E2 triggers the immediate rapid production of intracellular ROS ranging from a 1- to severalfold increase in a variety of cells. E2-stimulated ROS production does not correlate with the activity of the estrogen receptor (ER) in the cells. The ROS is most likely hydrogen peroxide based on its inhibition by antioxidants and catalase and lack of any effects of E2 on O(2)(*)(-) or NO(*) formation. Confocal microscopy showed that ROS is localized in the perinuclear mitochondria. E2 through anchorage- and integrin-dependent signaling to mitochondria increased ROS generation. Increased intracellular ROS formation identified here for the first time may explain the mechanism of previously reported oxidative damage and subsequent genetic alterations including mutations produced by elevated concentrations of estrogens. The functional consequences of E2-induced ROS formation included the enhanced cell motility as shown by the increase in cdc42 and activation of Pyk2 and the increased phosphorylation of signaling proteins c-jun and CREB. E2-induced ROS activated the binding of three oxidant-sensitive transcription factors: AP-1, CREB, and nuclear respiratory factor 1. In addition to ERs as signaling molecules, our findings further revealed that E2-induced mt ROS also act as signal transducing messengers and suggest new targets for the development of antioxidant-based drugs or antioxidant gene therapy for the prevention and treatment of estrogen-dependent cancer.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Estrogen, mitochondria, and growth of cancer and non-cancer cells.

In this review, we discuss estrogen actions on mitochondrial function and the possible implications on cell growth. Mitochondria are important targets of estrogen action. Therefore, an in-depth analysis of interaction between estrogen and mitochondria; and mitochondrial signaling to nucleus are pertinent to the development of new therapy strategies for the treatment of estrogen-dependent diseases related to mitochondrial disorders, including cancer.

Journal Article↗

PubMed2005

Mitochondrial signals to nucleus regulate estrogen-induced cell growth.

Classical genomic and non-genomic signaling pathways mediated by nuclear and cell membrane estrogen receptors are considered to contribute to estrogen-induced cell proliferation. Here we propose that mitochondrial signals to the nucleus regulate estrogen-induced progression of the cell cycle. The influence of estrogen on mitochondrial oxidative phosphorylation and mitochondrial gene transcription support the idea that mitochondria are significant targets of estrogen. Mitochondria are the major source of reactive oxygen species (ROS) in epithelial cells. Estrogen redox cycling within mitochondria also generates ROS. Antioxidants inhibit estrogen-induced cell growth. A-Raf, Akt, PKC, MEK, ERK, and transcription factors AP-1, NF-kappaB, and CREB are targets of both estrogen and ROS. We provide four lines of evidence in support of our hypothesis that estrogen-induced mitochondrial ROS stimulate redox sensor kinase A-Raf, Akt or PKC, which, in turn, activate transcription factors NF-kappaB, CREB, or AP-1 via the MEK/ERK pathway. Thus, estrogen-induced mitochondrial ROS leading to the activation of cell cycle genes containing AP-1, NF-kappaB, or CREB response elements are involved in the progression of the cell cycle of the estrogen-dependent cells. Our novel concept will contribute to the development of new targets in the prevention and control of estrogen-induced disease including cancer.

Animals↗

PubMed2004

Somatic mutations in stilbene estrogen-induced Syrian hamster kidney tumors identified by DNA fingerprinting.

Kidney tumors from stilbene estrogen (diethylstilbestrol)-treated Syrian hamsters were screened for somatic genetic alterations by Random Amplified Polymorphic DNA-polymerase chain-reaction (RAPD-PCR) fingerprinting. Fingerprints from tumor tissue were generated by single arbitrary primers and compared with fingerprints for normal tissue from the same animal, as well as normal and tumor tissues from different animals. Sixty one of the arbitrary primers amplified 365 loci that contain approximately 476 kbp of the hamster genome. Among these amplified DNA fragments, 44 loci exhibited either qualitative or quantitative differences between the tumor tissues and normal kidney tissues. RAPD-PCR loci showing decreased and increased intensities in tumor tissue DNA relative to control DNA indicate that loci have undergone allelic losses and gains, respectively, in the stilbene estrogen-induced tumor cell genome. The presence or absence of the amplified DNA fragments indicate homozygous insertions or deletions in the kidney tumor DNA compared to the age-matched normal kidney tissue DNA. Seven of 44 mutated loci also were present in the kidney tissues adjacent to tumors (free of macroscopic tumors). The presence of mutated loci in uninvolved (non-tumor) surrounding tissue adjacent to tumors from stilbene estrogen-treated hamsters suggests that these mutations occurred in the early stages of carcinogenesis. The cloning and sequencing of RAPD amplified loci revealed that one mutated locus had significant sequence similarity with the hamster Cyp1A1 gene. The results show the ability of RAPD-PCR to detect and isolate, in a single step, DNA sequences representing genetic alterations in stilbene estrogen-induced cancer cells, including losses of heterozygosity, and homozygous deletion and insertion mutations. RAPD-PCR provides an alternative molecular approach for studying cancer cytogenetics in stilbene estrogen-induced tumors in humans and experimental models. Although the exact functional importance of mutated loci is unknown, this study indicates that these altered loci may participate during tumor progression in the kidney.

Journal Article↗

PubMed2004

Age, sex and co-exposure to N-ethyl-N-nitrosourea influence mutations in the Alu repeat sequences in diethylstilbestrol-induced kidney tumors in Syrian hamsters.

We report, for the first time, mutations in the Alu repeat regions in the genome of kidney tumors induced by diethylstilbestrol in Syrian hamsters. Among the 66 loci amplified by 11 random primers, 28 loci exhibited insertions, deletions or losses or gains in intensity in the genome of kidney tumor tissues compared with normal kidney tissues from age-matched hamsters. Higher numbers of mutated Alu loci were observed in the tumors of old hamsters compared with young hamsters. In N-ethyl-N-nitrosourea- and diethylstilbestrol-treated hamsters deletion of a 0.59 kb locus amplified with primer OPC03 was observed in most of the female hamsters, but not in male hamsters. An insertion mutation of a 0.498 kb locus amplified with primer OPC03 was observed in 12 of 36 diethylstilbestrol-induced kidney tumors. The cloning and sequencing of the 0.498 kb locus amplified with primer OPC03 revealed that it had significant sequence similarity to the mouse RIKEN cDNA clone. These findings indicate that age, sex and co-exposure to N-ethyl-N-nitrosourea influence mutations in the Alu repeat sequences in the genome of diethylstilbestrol-induced kidney tumors in Syrian hamsters. Structural alterations in Alu repeats in critical target genes may be involved in diethylstilbestrol-induced carcinogenesis.

Age Factors↗

PubMed2003

Role of APC and DNA mismatch repair genes in the development of colorectal cancers.

Colorectal cancer is the third most common cause of cancer-related death in both men and women in the western hemisphere. According to the American Cancer Society, an estimated 105,500 new cases of colon cancer with 57,100 deaths will occur in the U.S. in 2003, accounting for about 10% of cancer deaths. Among the colon cancer patients, hereditary risk contributes approximately 20%. The main inherited colorectal cancers are the familial adenomatous polyposis (FAP) and the hereditary nonpolyposis colorectal cancers (HNPCC). The FAP and HNPCC are caused due to mutations in the adenomatous polyposis coli (APC) and DNA mismatch repair (MMR) genes. The focus of this review is to summarize the functions of APC and MMR gene products in the development of colorectal cancers.

Adenomatous Polyposis Coli Protein↗