No description available.

Dihydronicotinamide riboside (NRH) quinone oxidoreductase 2 (NQO2) is involved in quinone metabolism reducing quinone to hydroquinone. Quinones are products of oestrogen metabolism and are responsible for the oestrogen-initiated breast carcinogenesis. It has been demonstrated that oestrogen quinones are endogenous biological substrates of NQO2 which acting as a detoxification enzyme catalyses the reduction of oestrogen quinones to hydroquinone. Hydroquinone can then be removed by conjugation to glutathione or glucuronic acid. In this study, the oestrogen dependent and oestrogen independent effects of NQO2 in a variety of networks implicated in breast tumorigenesis were investigated aiming to understand the potential role of NQO2 overexpression in mammary carcinomas. The use of NRH as a cofactor for NQO2 is being studied in parallel with the Î2-oestradiol and tamoxifen treatments. The MCF-7, T47D, MDA-MB-231 and MDA-MB-468 breast cancer cells were transfected with increasing amounts of NQO2 and its biological activity in regulating ERα transcriptional activity, reactive oxygen species (ROS) generation, cell cycle control, mitochondrial membrane potential and antioxidant activities including catalase activity, glutathione (GSH) levels and glutathione peroxidase (GPx) activity were studied. NQO2 overexpression in MDA-MB-231 and T47D cells reduced ROS generation. Increasing amounts of transfected NQO2 induced the ERα transcriptional activity in Î2-oestradiol treated MCF-7 and T47D cells and decreased cyclin D1 protein levels in these cells treated with Î2-oestradiol compared to untransfected cells. Reduction of catalase activity was detected in tamoxifen treated T47D cells overexpressing NQO2, an effect that was not evident in Î2-oestradiol treated cells, whereas NQO2 mediated reduction of GSH levels was detected in these cells treated with Î2-oestradiol but not with tamoxifen. Finally, NQO2 affected mitochondrial membrane depolarization in Î2-oestradiol treated MDA-MB-231 cells. Given the fact that NRH is not physiologically synthesized in humans, the results presented in this study are valuable from the fundamental science point of view indicating the existence of a potential link between NQO2 and estrogens affecting a number of biological pathways important for breast carcinogenesis and as such from the clinical angle it could be assumed that NQO2 effects could impact the design of personalised breast cancer treatment of oestrogen receptor positive and negative breast cancers.

Docetaxel (DTX)-based regimen is the mainstay treatment against castration resistant prostate cancer (CRPC). However, significant side-effects of DTX mandate that strategies to chemosensitize CRPC cells be utilized. We investigated whether physiologically achievable concentrations of nelfinavir (NFR) and curcumin (CUR), known to target the endoplasmic reticulum (ER) stress and AKT pathways, can increase DTX cytotoxicity. A significant reduction (~70%) in survival of a CRPC cell line, C4-2B, was evident within 24 hrs post-exposure to a combination of DTX (10 nM), NFR (5 µM) and CUR (5 µM), as compared to DTX alone (~34%). This rapid cytotoxicity was not seen in non-tumorigenic RWPE-1 cells as well as in primary prostate epithelial cells (PrEC) and bone-marrow mesenchymal stem cells (BM-MSC). A significant increase in apoptosis was seen in C4-2B cells but not RWPE-1 cells, as indicated by DNA-fragmentation, caspase-3 assay, and PARP cleavage. A significant reduction in C4-2B-derived colony forming units (CFU) was observed following exposure to DTX-NFR-CUR combination (92%), as compared to DTX alone (34%). In C4-2B cells, immunodetection and real-time PCR studies showed that exposure to 3-drug combination drastically reduced AKT activation, increased unfolded protein response (UPR) markers, such as XBP-1 mRNA and phosphorylated eIF-2α, and increased ER-stress induced pro-apoptotic markers such as CHOP, ATF4 and TRIB3. In RWPE-1 cells, upregulation of CHOP was observed with DTX-NFR-CUR combination, but no increase in ATF-4 and TRIB3 were observed. In vivo studies using C4-2B tumor xenografts showed a significant reduction in tumor volume following 4 week exposure to the 3-drug combination, as compared to DTX alone. Immunohistochemistry (IHC) of tumor sections revealed decreased Ki-67 staining indicating reduced cell proliferation and increased TUNEL staining indicating apoptosis, in DTX-NFR-CUR treated mice as compared to DTX alone. Therefore, our studies show that NFR and CUR can provide a promising approach as an adjuvant therapy to chemosensitize CRPC to DTX therapy. / acase@tulane.edu

<p>Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with an incidence of 1.5-2.7/100000 people/year. Today there is no cure for the disease and only symptomatic treatments are available. ALS progresses rapidly and only 50% of the patients are alive three years after the symptom debut. In ALS, the upper and lower motor neurons undergo degeneration in a process resembling apoptosis. This leads to muscle atrophy and paralysis. The causes of neuronal death are however unknown. In this thesis we have studied transgenic mice carrying human mutant superoxide dismutase, as a model for familial ALS. These mice develop ALS-like symptoms after four months of age with degeneration of the motor neurons. Our results show an involvement of endoplasmic reticulum stress, caspase-12, -9, -3 and procaspase-7 in the ALS mice spinal cord. Overexpression of the antiapoptotic protein XIAP in spinal cord neurons inhibited the activation of caspase-12 and reduced caspase-3 and calpain activity. Calpastatin, the regulator of calpain activity, was kept intact in the ALS-XIAP mice. These mice showed a 12% increase in the mean survival suggesting a beneficial effect of XIAP in ALS. The reason for the ultimate cell death of motor neurons in the ALS-XIAP mice may be due to the activation of additional cell death pathways. Thus, we observed that lysosomal proteases particularly, cathepsinB, -D, and -L were activated in the ALS mice spinal cord together with a less marked upregulation of the inhibitors, cystatinB and -C. We also found activation of astrocytes and microglial cells in the spinal cord of ALS mice indicating their involvement in the disease. The results show that both caspase-dependent and -independent pathways are activated during neuronal degeneration in the ALS spinal cord. The results obtained may help to identify novel drug targets for future treatments of ALS.</p>

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with an incidence of 1.5-2.7/100000 people/year. Today there is no cure for the disease and only symptomatic treatments are available. ALS progresses rapidly and only 50% of the patients are alive three years after the symptom debut. In ALS, the upper and lower motor neurons undergo degeneration in a process resembling apoptosis. This leads to muscle atrophy and paralysis. The causes of neuronal death are however unknown. In this thesis we have studied transgenic mice carrying human mutant superoxide dismutase, as a model for familial ALS. These mice develop ALS-like symptoms after four months of age with degeneration of the motor neurons. Our results show an involvement of endoplasmic reticulum stress, caspase-12, -9, -3 and procaspase-7 in the ALS mice spinal cord. Overexpression of the antiapoptotic protein XIAP in spinal cord neurons inhibited the activation of caspase-12 and reduced caspase-3 and calpain activity. Calpastatin, the regulator of calpain activity, was kept intact in the ALS-XIAP mice. These mice showed a 12% increase in the mean survival suggesting a beneficial effect of XIAP in ALS. The reason for the ultimate cell death of motor neurons in the ALS-XIAP mice may be due to the activation of additional cell death pathways. Thus, we observed that lysosomal proteases particularly, cathepsinB, -D, and -L were activated in the ALS mice spinal cord together with a less marked upregulation of the inhibitors, cystatinB and -C. We also found activation of astrocytes and microglial cells in the spinal cord of ALS mice indicating their involvement in the disease. The results show that both caspase-dependent and -independent pathways are activated during neuronal degeneration in the ALS spinal cord. The results obtained may help to identify novel drug targets for future treatments of ALS.

The unfolded protein response, which is activated during ER stress, counteracts stress conditions by increasing folding capacity and by increasing the degradation of misfolded ER proteins by the ER-Associated Degradation (ERAD) system. Studies using an engineered insulinoma cell line with inducible expression of the Akita folding-deficient insulin have shown a large induction of Herp, a protein that has been implicated in the ERAD pathway. We hypothesized that Herp is an essential protein that regulates the degradation of misfolded insulin during the ER stress response. Indeed, we found that the degradation of mutant insulin is Herp-dependent and that maintaining Herp expression is vital for maintaining cell survival. We have also observed that the expression of Herp mRNA and protein is induced in various cell culture and animal models of diabetes. These results suggest that Herp is an important ER stress response protein that is induced under diabetic conditions in pancreatic β-cells.

The unfolded protein response, which is activated during ER stress, counteracts stress conditions by increasing folding capacity and by increasing the degradation of misfolded ER proteins by the ER-Associated Degradation (ERAD) system. Studies using an engineered insulinoma cell line with inducible expression of the Akita folding-deficient insulin have shown a large induction of Herp, a protein that has been implicated in the ERAD pathway. We hypothesized that Herp is an essential protein that regulates the degradation of misfolded insulin during the ER stress response. Indeed, we found that the degradation of mutant insulin is Herp-dependent and that maintaining Herp expression is vital for maintaining cell survival. We have also observed that the expression of Herp mRNA and protein is induced in various cell culture and animal models of diabetes. These results suggest that Herp is an important ER stress response protein that is induced under diabetic conditions in pancreatic β-cells.

No description available.

Endoplasmic reticulum (ER) stress has been implicated as a causative factor in the development of pancreatic beta-cell dysfunction and death resulting in type 2 diabetes. This thesis examined the role of ATF6beta in the ER stress response of beta-cells. Using an ATF6beta-specific antibody, expression of full-length ATF6beta was detected in various insulinoma cell lines and rodent islets and the induction of the active form (ATF6beta-p60) under ER stress conditions. Knock-down of ATF6beta in INS-1 832/13 cells did not affect mRNA induction of known ER stress response genes in response to tunicamycin-induced ER stress, however it increased the susceptibility of beta-cells to apoptosis. Conversely, overexpression of ATF6beta-p60 reduced the apoptotic phenotype. Microarray results suggest ATF6beta functions to induce expression of adaptive genes also regulated by ATF6alpha, but also several specific targets genes. These findings have increased our understanding of the role of ATF6beta in the ER stress response of beta-cells.

Endoplasmic reticulum (ER) stress has been implicated as a causative factor in the development of pancreatic beta-cell dysfunction and death resulting in type 2 diabetes. This thesis examined the role of ATF6beta in the ER stress response of beta-cells. Using an ATF6beta-specific antibody, expression of full-length ATF6beta was detected in various insulinoma cell lines and rodent islets and the induction of the active form (ATF6beta-p60) under ER stress conditions. Knock-down of ATF6beta in INS-1 832/13 cells did not affect mRNA induction of known ER stress response genes in response to tunicamycin-induced ER stress, however it increased the susceptibility of beta-cells to apoptosis. Conversely, overexpression of ATF6beta-p60 reduced the apoptotic phenotype. Microarray results suggest ATF6beta functions to induce expression of adaptive genes also regulated by ATF6alpha, but also several specific targets genes. These findings have increased our understanding of the role of ATF6beta in the ER stress response of beta-cells.