Category: Apoptosis Compound Library

In this study we hypothesized that methylation of key genes is a molecular mechanism leading to cisplatin resistance. We decided to investigate DNA methylation as a resistance mechanism because it is reversible by available drugs. We used SCC-25 and its cisplatin-resistant counterpart, SCC-25/CP, and determined that pre-treatment with the demethylating drug decitabine enhanced the anti-proliferative and apoptotic effect of cisplatin on these cell lines. In our HNSCC mouse model, combination treatment with decitabine and cisplatin produced a more robust anti-tumor effect than either drug alone. Decitabine pre-treatment in vitro reversed cisplatin-resistance in SCC-25/CP cells, and lowered the dose of cisplatin required to produce antiproliferative or apoptotic effects. Interestingly, decitabine pretreatment also lowered the dose of cisplatin required for cisplatinsensitive SCC-25 cells. The clinical significance of our results is that decitabine could salvage patients with cisplatin-resistant tumors; moreover, allowing for reduced toxicity. Previous studies have explored the effectiveness of epigenetic therapy in rescuing cisplatin resistance in other cancers. Adding hydralazine and valproate to cisplatin therapy significantly increased progression-free survival in advanced stage cervical cancer patients. A phase I trial for patients with solid tumors showed that combination treatment of decitabine followed by carboplatin is safe. A phase II study adding valproate and hydralazine to the same schedule of chemotherapy on which patients with solid cancers were progressing showed clinical benefit in 12 of 15 patients. At the same time there have been studies adding demethylating agents to platinum-based chemotherapy with negative results. A phase II trial randomized ovarian cancer patients progressing 6–12 months after previous platinum therapy to one of two groups: one group would receive decitabine with carboplatin, and the second group would receive carboplatin alone. However the study closed after an interim BMS-907351 analysis showed that the combination group had lack of efficacy and poor treatment deliverability. Our dose scheduling of decitabine and cisplatin is based on previous work in ovarian and colon carcinoma showing that multiple doses of decitabine are required prior to cisplatin administration to maximally sensitize xenografts to cisplatin. In addition to reduced survival, head and neck cancer patients have significant function-limiting pain, which is either cancerinduced or treatment-induced. While survival and pain seem like unrelated issues, a recent randomized clinical trial shows that aggressive pain management in advanced-stage cancer patients significantly improves quality of life and increases survival. Peripheral neuropathy is a major toxic side effect of cisplatin and contributes to pain. The behavioral assay that we used on our preclinical model detects both cancer-induced pain and neuropathic pain. We showed that combination therapy of decitabine and cisplatin resulted in significantly reduced mechanical pain. While nociception in our preclinical model was likely cancer-induced, decitabine treatment potentially reduces the required cisplatin dose, thus minimizing peripheral neuropathy.

Breath-hold imaging and respiratory triggering have been suggested as techniques to overcome these problems. DTI is a development from diffusion-weighted MRI, which allows the quantification of diffusion in different directions. Diffusion anisotropy is related to structural organization and therefore could be compromised in a pathological process. Molecular diffusion, however, is a three-dimensional process which can occur with different probabilities in each direction, i.e. in an anisotropic manner. This is the case in the kidney, which has a well-defined structure with tubules, collecting ducts and vessels radially oriented towards the pelvis and in which molecules move in a preferential direction. The measurement of global diffusion and the direction of the diffusion is necessary to investigate molecular diffusion in the kidney. DTI can provide three indices related to the magnitude of diffusivity from the mathematical description of the system. These indices are the mean, axial and radial diffusivity. MD is the average of the average diffusion coefficient in all three directions and is a reflection of the magnitude of the tensor that describes the system. AD is the first eigenvalue, and occurs in the longitudinal direction of the tensor. RD is the average of the second and third eigenvalues. It is related to diffusion along the radial direction. The three indices are related to diffusional anisotropy and fractional anisotropy. The measurement of MD, AD, RD and FA in a healthy kidney has not yet been reported in the literature. The aim of our study was to evaluate the diffusivity characteristics of the renal cortex and medulla and provide baseline data for future studies. In this pilot study, we identified significantly higher mean cortical MD, l2, l3, and RD. The primary eigenvalue l1 was the largest and least restricted diffusivity and, in a medullary tubule, reflected motion along the length of the tubule. This included intratubular flow, whose direction was specified by the primary diffusion eigenvector, The secondary and tertiary eigenvalues reflected lower restricted diffusion orthogonal to l1. In the medulla this corresponded to cross-tubule or transtubular motion. These differences in DTI indices reflected the renal Vismodegib 879085-55-9 anatomic and physiological structure. The chief function of the kidney is filtration of plasma and formation of urine. The renal blood flow, in particular blood flow to the renal cortex, is much greater than that needed for the metabolic requirements of the kidney. Most blood is directed towards the renal cortex to optimize glomerular filtration and reabsorption of solute. The renal cortex requires rich perfusion to function properly, while the renal medulla requires limited blood flow. The maintenance of a relatively low medullary blood flow appears to be critical for maintaining the cortical-medullary solute gradient and, therefore, urinary concentrating mechanisms. Blood is supplied to the renal medulla from the vasa recta capillaries. The vasa recta capillaries arise from the efferent arterioles of the juxtamedullary glomeruli, which comprise about 10% of all glomeruli in the kidney. While all blood flow to the kidney enters the renal cortex, only about 10% reaches the renal medulla.

Genetic characterization of viruses isolated in the environment can provide interesting information regarding gene prevalence and circulation in habitats used by waterfowl. Such information is critical to assess the possibility of inter-annual persistence in water, long-term circulation of environmentally-isolated virus strains in wild duck populations, and identify XAV939 potential genetic basis for the persistence of IA viruses in water. Previous studies have demonstrated differences in the ability of IA viruses to remain infective in water and have suggested that subtyperelated variations in persistence may exist, especially at low temperatures. Both isolates tested in our study persisted for several months in distilled water at constant temperatures, below 17uC and at neutral pH. Overall, the estimated persistence was higher than reported for 12 different waterfowl derived viruses. Limited data precludes conclusions related to increased environmental persistence associated with viruses recovered from the environment. Future experiments should however consider such a possibility as the demonstration of long-time persistence of water-isolated viruses would suggest the potential for inter-annual persistence in aquatic habitats. Inversely, habitats characterized by deep water may prevent freezing and strong temperature changes affecting viral persistence, but are less likely to be used by dabbling ducks. Viral persistence in frozen pond and lake water has been suggested to be an potential mechanisms for inter-annual persistence and source of contamination for waterfowl in breeding grounds. In high latitude habitats, shallow lakes and ponds may freeze relatively quickly during fall and winter, potentially reducing effects of such temperature changes. The effects of latitudinal-dependent temperature regimes on surface water viruses warrant future experimental work. Because diurnal surface water temperature fluctuations could represent a constraint on viral persistence, we also investigated the effects of temperature variations between 17uC and 23uC. Compared to results from constant temperature, no effects on viral persistence were observed. This suggests that diurnal surface water temperature fluctuations are not likely to significantly affect virus persistence, although as for freeze-thaw cycles additional environmental simulation studies would be required to confirm this trend. Experimental infections provided evidence that both waterisolated IA viruses replicated efficiently in Mallards and, in both cases, shedding patterns were consistent with a previous study performed with duck-isolated LP IA viruses. These results support that viruses isolated from surface water replicate in ducks as well as LP virus isolates that have a wild duck-origin. In this study, we highlighted that water-isolated IA viruses can provide complementary information regarding circulating viruses and viral genes in wild waterfowl populations. With current methodological limitations the recovery of viruses from aquatic habitats should not be considered as a replacement of traditional surveillance approaches utilizing wild bird or fecal sampling.

In conclusion, by mapping DNA methylated viral integration sites in murine leukemias induced by retroviral integration mutagenesis followed by comparative analysis in human AML, we identified PTP4A3 not only as a candidate HIG contributing to leukemogenesis in mice but also as an independent prognostic indicator in human AML. We designed a strategy to identify candidate HIGs in AML using retroviral integration mutagenesis, by mapping DNA methylated proviral integrations. By using HAT, we deliberately aimed at detecting integrations present in the majority of the leukemic cells, which are most likely involved in the early phase of leukemogenesis. At the same time, integrations present in subclones that contribute to later stages of leukemic progression will be missed using this approach. We identified 6 genes that are flanked by methylated viral integrations. Expression analysis showed that Lrmp, Hcls1 and Prkrir ) were up regulated and Ptp4a3, a phosphatase also known as Prl3 was down regulated in the respective murine tumor. These results indicate that a flanking methylated viral integration site does not necessarily lead to transcriptional repression. As 1 out of 4 genes flanked by a mVIS was transcriptionally down regulated and expression of the 2 other genes could not be investigated, the efficiency to detect potential HIGs by identifying mVIS would approximately be 17–25%. However, the number of analysed tumors is too small to allow an accurate estimation of the efficiency. Ptp4a3 expression is controlled by p53 induced after DNA damage in mouse embryonic fibroblasts and its activity is involved in inducing a G1 cell cycle arrest in these cells. Surprisingly however, the same study also demonstrated a cell cycle arrest upon reduction of PTP4A3 expression. Apparently, depending on expression level dosage, PTP4A3 may have both positive and negative effects on cell cycle regulation. Hence, PTP4A3 haplo-insufficiency, but not its complete loss, may lead to an impairment of cell cycle arrest after DNA damage. Dosage effects of PTP4A3 expression in relation to cellular responses may be more complex, particularly in cancer cells. For example, in carcinoma cell lines PTP4A3 expression may lead to down regulation of p53 and it is variably induced by c-irradiation. Finally, high PTP4A3 expression has been linked to increased tumor aggressiveness in different types of solid tumors, e.g., melanoma, gastric cancer, colon cancer, hepatocellular carcinoma and breast cancer, possibly because high PTP4A3 expression leads to increased epithelial-mesenchymal transition. The role of PTP4A3 in hematopoietic malignancies has not been studied as XL-184 extensively as in carcinoma. Only a few studies report differences in expression levels of PTP4A3 in ALL and myeloma subgroups, based on gene expression profiling. Interestingly however, in a recent study, PTP4A3 has been proposed to have a role in drug-resistance in AMLs with internal tandem duplication of FLT3. This finding, together with the observation that high PTP4A3 expression negatively correlates with prognostic outcome, indicates that PTP4A3 might be a potential therapeutic target in AML.

Susceptibility genes related to PCa might function in host immune responses and protection against cell and DNA damage caused by oxidative agents. For example, two suggested susceptibility risk genes for hereditary PCa, RNASEL and MSR1, are both involved with innate immunity. Lymphoblastoid cell lines represent an essential component of the immune response, so this result may indicate that ARLTS1 has a function in immune system processes. Alterations in important molecular pathways involved in PCa have been implicated in proliferative inflammatory atrophy and prostatic intraepithelial neoplasia lesions. Tumor suppressor genes NKX3.1, CDKN1B which encodes p27 and the phosphatase and tensin homologue are highly expressed in normal prostate epithelium and have shown to be down-regulated or absent in PIN and PCa. Since ARLTS1 acts as a tumor suppressor protein and has a decreased expression in PCa, these recent findings are in line with the results from other suggested PCa tumor suppressor proteins. Previously it has been shown that ARLTS1 induces apoptosis in lung cancer cells and in ovarian carcinoma. In the case of prostatic inflammation and antigen engagement, the need for apoptosis increases and the processes of the immune system, together with endogenous inflammatory cells become PD325901 activated. Here we showed that in the lymphoblastoid cell lines of PCa patients, ARLTS1 expression was significantly decreased among the CC carrying patients compared to the wild-type allele T carrying patients. The lymphoblastoid cell lines were derived by Epstein-Barr virus transformation of peripheral mononuclear leucocytes from patients, indicating that these cells have encountered antigen stimuli via viral infection. The CC carrying patients had a low ARLTS1 expression status suggesting that ARLTS1 function is decreased due to this risk genotype and consequently this leads to decreased apoptosis. This may indicate that the Cys148Arg CC genotype contributes to the immune response by diminishing apoptosis rates, decreasing defense mechanisms and finally cancer progression. It has been shown earlier that lung cancer cells carrying the Trp149Stop variant and expressing the truncated protein had a reduced capability to induce apoptosis compared to cells expressing the full-length protein. This reduced apoptosis could also be the causal factor in PCa. Our data suggest for the first time that the predisposing effect of the CC genotype of Cys148Arg is related to reduced expression in immune system cells rather than in tumor cells where ARLTS1 expression is naturally very low. Like all other organs, the normal prostate contains endogenous inflammatory cells and immune response mechanisms. Consequently, the function of ARLTS1 may not exclusively be based on tumor suppression as suggested before, but also on immune response functions that occur either locally in prostate or in peripheral tissues. This is in line with the findings that PCa is a very heterogeneous disease and different mechanisms of cancer progression may occur.