Inhibition of branched-chain alpha-keto acid dehydrogenase kinase augments the sensitivity of ovarian and breast cancer cells to paclitaxel.

CONTEXT: Many cancer patients who initially respond to chemotherapy eventually develop chemoresistance, and to address this, we previously conducted a RNAi screen to identify genes contributing to resistance. One of the hits from the screen was branched-chain α-keto acid dehydrogenase kinase (BCKDK). BCKDK controls the metabolism of branched-chain amino acids (BCAAs) through phosphorylation and inactivation of the branched-chain α-keto acid dehydrogenase complex (BCKDH), thereby inhibiting catabolism of BCAAs. METHODS: We measured the impact on paclitaxel sensitivity of inhibiting BCKDK in ovarian and breast cancer cell lines. RESULTS: Inhibition of BCKDK using siRNA or two chemical inhibitors (BCKDKi) was synergistic with paclitaxel in both breast and ovarian cancer cells. BCKDKi reduced levels of BCAA and the addition of exogenous BCAA suppressed this synergy. BCKDKi inactivated the mTORC1-Aurora pathway, allowing cells to overcame M-phase arrest induced by paclitaxel. In some cases, cells almost completed cytokinesis, then reverted to a single cell, resulting in multinucleate cells. CONCLUSION: BCKDK is an attractive target to augment the sensitivity of cancer cells to paclitaxel.

Vitamin D and Immunoglobulin E Status in Allergic Rhinitis Patients Compared to Healthy People.

Allergic rhinitis (AR) is a type of inflammatory condition that includes a group of symptoms, mainly affecting the nasal mucosa. Nasal obstruction, sneezing, stuffy or runny nose, in addition to swollen, itchy, red and watery eyes are the most common symptoms of the disease. These symptoms are triggered as a result of increased inflammatory mediators such as histamine and leukotrienes. Studies have recently shown the role of vitamin D (vit.D) in many allergic and immune conditions, where receptors for the active form of vit.D (1,25-dihydroxyvitamin D3) have been discovered on the surface of almost all types of inflammatory cells. Therefore, the present study was conducted to explore the level of vit. D in AR patients and its correlation with the severity of the disease. Two groups participated in the study; the first group included 49 patients who were diagnosed in a private otolaryngology clinic by the first author as having allergic rhinitis (AR group). The second one served as a control group and included 50 apparently healthy volunteers with no history of AR. The mean level of IgE and vit. D was found to be 326.3 and 10.2 ng/ml in the AR group, respectively, and 30.8 and 23.3 ng/ml in the control group, respectively. Ninety-three percent of AR patients have shown a deficiency in vit. D level, where 56% of this group showed severe deficiency. On the other hand, 34% of the control group has shown an insufficient level of vit. D. Additionally, 64% of AR patients have shown serum levels of IgE at values ranging between 100-299 ng/ml. Higher serum levels of IgE at values ranging between 300-599 ng/ml and 600-1000 ng/ml were observed in 25% and 11% of AR patients, respectively. The prevalence of low levels of vit. D in the AR group was significantly higher than that in the control group (P < 0.001). Vit. D deficiency is significantly related to severe AR symptoms and measuring serum vit. D level is recommended in the management plan of this group of patients.

Screening a library of approved drugs reveals that prednisolone synergizes with pitavastatin to induce ovarian cancer cell death.

The survival rate for patients with ovarian cancer has changed little in the past three decades since the introduction of platinum-based chemotherapy and new drugs are needed. Statins are drugs used for the treatment and prevention of cardiovascular diseases. Recent work from our laboratory has shown that pitavastatin has potential as a treatment for ovarian cancer if dietary geranylgeraniol is controlled. However, relatively high doses of statins are required to induce apoptosis in cancer cells, increasing the risk of myopathy, the most common adverse effect associated with statins. This makes it desirable to identify drugs which reduce the dose of pitavastatin necessary to treat cancer. A drug-repositioning strategy was employed to identify suitable candidates. Screening a custom library of 100 off-patent drugs for synergistic activity with pitavastatin identified prednisolone as the most prominent hit. Prednisolone potentiated the activity of pitavastatin in several assays measuring the growth, survival or apoptosis in several ovarian cancer cells lines. Prednisolone, alone or in some cases in combination with pitavastatin, reduced the expression of genes encoding enzymes in the mevalonate pathway, providing a mechanistic explanation for the synergy.

Inhibition of the mevalonate pathway augments the activity of pitavastatin against ovarian cancer cells.

Only 40% of patients with advanced ovarian cancer survive more than 5 years. We have previously shown that pitavastatin induces regression of ovarian cancer xenografts in mice. To evaluate whether the response of ovarian cancer cells to pitavastatin is potentiated by farnesyl diphosphate synthase inhibitors or geranylgeraniol transferase I inhibitors, we evaluated combinations of pitavastatin with zoledronic acid, risedronate and GGTI-2133 in a panel of ovarian cancer cells. Pitavastatin (IC50 = 0.6-14 µM), zoledronic acid (IC50 = 21-57 µM), risedronate (IC50 > 100 µM) or GGTI-2133 (IC50 > 25 µM) inhibited the growth of ovarian cancer cell cultures. Combinations of pitavastatin with zoledronic acid displayed additive or synergistic effects in cell growth assays in 10 of 11 cell lines evaluated as well as in trypan blue exclusion, cellular ATP or caspase 3/7, 8 and 9 assays. Pitavastatin reduced levels of GGT-IIß and the membrane localization of several small GTPases and this was potentiated by zoledronic acid. siRNA to GGT-Iß and GGT-IIß used in combination, but not when used individually, significantly increased the sensitivity of cells to pitavastatin. These data suggest that zoledronic acid, a drug already in clinical use, may be usefully combined with pitavastatin in the treatment of ovarian cancer.

Antagonism of Bcl-XL is necessary for synergy between carboplatin and BH3 mimetics in ovarian cancer cells.

BACKGROUND: BH3 mimetics are a class of drugs that antagonize the Bcl-2 family of apoptosis inhibitors. We have previously shown that these compounds can potentiate the activity of carboplatin against several ovarian cancer cell lines. However, recent clinical studies have highlighted that BH3 mimetics which antagonise Bcl-XL are associated with significant thrombocytopenia. This has led to the development of ABT-199 which specifically inhibits Bcl-2. Unfortunately, Bcl-XL appears to be more frequently deregulated in ovarian cancer than Bcl-2. We therefore compared the ability of ABT-199, and the Bcl-XL selective compound WEHI-539, to potentiate the activity of carboplatin in ovarian cancer cell lines. METHODS: WEHI-539, ABT-737 and ABT-199 were tested in combination with carboplatin using a panel of 6 ovarian cancer cell lines. The activity of the drugs was evaluated using cell growth assays, staining with trypan bue and measurement of apoptosis by measuring caspase 3/7 activity, PARP cleavage and annexin-V/propidium iodide staining. RESULTS: We found that WEHI-539 and ABT-737, but not ABT-199, were synergistic with carboplatin in cell growth assays and potentiated cell death when assessed by trypan blue staining. Furthermore, WEHI-539 and ABT-737 augmented carboplatin induced caspase 3/7 activity, PARP cleavage and annexin V labelling, but ABT-199 failed to do so. CONCLUSIONS: These observations suggest that compounds which target Bcl-XL are necessary if BH3 mimetics are to be successfully used to treat patients with ovarian cancer and this highlights the need to develop strategies to minimize thrombocytopenia induced by such compounds.

Effects of blocking of angiotensin system on the prevalence of metabolic syndrome in type 2 diabetic patients.

OBJECTIVE: To evaluate prevalence of metabolic syndrome in hypertensive type 2 diabetic patients treated with antihypertensive drugs that inhibit renin angiotensin system. METHODOLOGY: Two groups of patients were included in this study. The first group involved 130 hypertensive type 2 diabetic patients taking enalapril, captopril (Converting Enzyme inhibitors), valsartan or telmisartan (Angiotensin II receptor blockers) as monotherapy whereas group 2 involved 92 type 2 diabetic patients with normal blood pressure. Metabolic syndrome was diagnosed according to criteria made by the US National Cholesterol Education Program Adult Treatment Panel III. Serum glucose concentration, serum triglycerides and HDL-cholesterol were measured by using special kits. RESULTS: The percentage of patients having metabolic syndrome was lower in group 1 (58.47%) as compared with group 2 (73%). Waist circumferences, triglycerides and FBS were significantly lower in group 1 as compared with group 2. BP and HDL-cholesterol were significantly higher in group 1 as compared with group 2. CONCLUSION: Inhibition of RAS by converting enzyme inhibitors or angiotensin II receptor blockers captopril, enalapril, valsartan or telmisartan produce beneficial effects on the markers of metabolic syndrome and can reduce the frequency of metabolic syndrome in type 2 diabetic patients.