Inhibition of mitochondrial respiration prevents BRAF-mutant melanoma brain metastasis

Melanoma patients carry a high risk of developing brain metastases, and improvements in survival are still measured in weeks or months. Durable disease control within the brain is impeded by poor drug penetration across the blood-brain barrier, as well as intrinsic and acquired drug resistance. Augmented mitochondrial respiration is a key resistance mechanism in BRAF-mutant melanomas but, as we show in this study, this dependence on mitochondrial respiration may also be exploited therapeutically. We first used high-throughput pharmacogenomic profiling to identify potentially repurposable compounds against BRAF-mutant melanoma brain metastases. One of the compounds identified was β-sitosterol, a well-tolerated and brain-penetrable phytosterol. Here we show that β-sitosterol attenuates melanoma cell growth in vitro and also inhibits brain metastasis formation in vivo. Functional analyses indicated that the therapeutic potential of β-sitosterol was linked to mitochondrial interference. Mechanistically, β-sitosterol effectively reduced mitochondrial respiratory capacity, mediated by an inhibition of mitochondrial complex I. The net result of this action was increased oxidative stress that led to apoptosis. This effect was only seen in tumor cells, and not in normal cells. Large-scale analyses of human melanoma brain metastases indicated a significant role of mitochondrial complex I compared to brain metastases from other cancers. Finally, we observed completely abrogated BRAF inhibitor resistance when vemurafenib was combined with either β-sitosterol or a functional knockdown of mitochondrial complex I. In conclusion, based on its favorable tolerability, excellent brain bioavailability, and capacity to inhibit mitochondrial respiration, β-sitosterol represents a promising adjuvant to BRAF inhibitor therapy in patients with, or at risk for, melanoma brain metastases.publishedVersio

Thioridazine inhibits autophagy and sensitizes glioblastoma cells to temozolomide

Glioblastoma multiforme (GBM) has a poor prognosis with an overall survival of 14–15 months after surgery, radiation and chemotherapy using temozolomide (TMZ). A major problem is that the tumors acquire resistance to therapy. In an effort to improve the therapeutic efficacy of TMZ, we performed a genome‐wide RNA interference (RNAi) synthetic lethality screen to establish a functional gene signature for TMZ sensitivity in human GBM cells. We then queried the Connectivity Map database to search for drugs that would induce corresponding changes in gene expression. By this approach we identified several potential pharmacological sensitizers to TMZ, where the most potent drug was the established antipsychotic agent Thioridazine, which significantly improved TMZ sensitivity while not demonstrating any significant toxicity alone. Mechanistically, we show that the specific chemosensitizing effect of Thioridazine is mediated by impairing autophagy, thereby preventing adaptive metabolic alterations associated with TMZ resistance. Moreover, we demonstrate that Thioridazine inhibits late‐stage autophagy by impairing fusion between autophagosomes and lysosomes. Finally, Thioridazine in combination with TMZ significantly inhibits brain tumor growth in vivo, demonstrating the potential clinical benefits of compounds targeting the autophagy‐lysosome pathway. Our study emphasizes the feasibility of exploiting drug repurposing for the design of novel therapeutic strategies for GBM.</p

Growth dynamics of the vestibular schwannoma

Introduction: Studies concerning vestibular schwannoma (VS) are inconsistent in reporting of tumor size and growth. This means that results found in one paper using one set of definitions cannot be compared directly with results found in another paper with another set of definitions. It is a challenge to make clinical decisions from studies with such disparate definitions, as it is difficult to know how reliable the individual findings are. This thesis thus aimed to empirically evaluate these different means of reporting tumor size and growth that can be found in the literature. In addition to this, we also present our own findings of the growth dynamics and predictors of untreated VS, as well as evaluating the treatment outcome and complication rates for tumors treated by gamma knife radiosurgery (GKRS). Methods: The management of VS patients is determined primarily based on the tumor size and observed tumor growth. The smallest tumors are conservatively treated by serial scans, and if growth is detected, they are offered active treatment by either microsurgery or GKRS. The papers in this thesis primarily focus on the conservatively treated cohort, and those among them that were later treated by GKRS. Tumor volumes were estimated by manual tracing on MRI. Mixed effects modeling was used to analyze relationships between observations. Results: The papers included in this thesis present a number of results. The first paper found several inherent flaws with the most commonly used measure, the maximum diameter. Empirical proportionality coefficients which were quite similar to theoretical values used in the literature were also found. The second paper showed that tumor growth was best described by volume doubling time (VDT) rather than in terms of mm/year. We found a VDT of 4.40 years among our cohort. We also discussed the use of a cutoff of 1 mm/year to distinguish between growing and non-growing tumors, and proposed a VDT cutoff of 5.22 years that could be used similarly. None of the baseline parameters investigated were predictive of tumor growth. The third paper described the risk of needing treatment with the wait-and-scan protocol to be 13.3% at two years, and 41.3% at five years. The study also found a decline of hearing function for conservatively managed patients. Neither tinnitus nor unsteadiness changed significantly from baseline, but there was a reduction in the number of patients reporting vertigo. Results also suggest that tumor growth may be associated with progression of tinnitus and imbalance problems. The fourth paper found a radiological tumor control rate of 71.1%. Higher age and larger tumor size were found to be positively associated with tumor control. Hearing was preserved in 79% of the patients who had serviceable hearing at the time of treatment. Permanent facial weakness as a result of GKRS treatment occurred in one patient. In terms of QoL, bodily pain and general health scores improved significantly after GKRS. Social function steadily declined throughout the follow-up period, which may be related to the increasing number of patients experiencing unilateral hearing loss. Conclusion: In the discussion of inconsistencies in reporting of tumor size and tumor growth, our studies propose that there exist both empirical and biological arguments for the use of volumes and VDT’s rather than diameters and linear growth rates. A VDT cutoff of 5.22 years can distinguish between clinically growing and non-growing tumors. Our findings support the continued use of a conservative approach among small, non-growing tumors. For medium-sized or growing tumors, we also suggest that GKRS is a preferable treatment to microsurgery, given the high tumor control rates and low rates of complication with GKRS. The tumor control can also be improved by taking into consideration the potential predictors found in our study when selecting patients for this treatment, namely the patient’s age and the tumor size (although from a radiobiological point of view, one would expect the opposite effect from these parameters). Several scales of QoL were also found to improve significantly after GKRS, thus supporting the practice of recommending this form of treatment to these tumors. The social function scale however got steadily worse from baseline

ASSESSMENT & EVALUATION ON THE KNOWLEDGE, ATTITUDE & PRACTICE TOWARDS MEDICATION THERAPY MANAGEMENT AMONG COMMUNITY OF DAVANGERE CITY

Objectives: The prime objective of this study is to assess knowledge, attitude, and practice (KAP) toward medications in a community of Davangere city.Methods: This community-based study was conducted for 6 months using medication therapy management aspects. Ethical clearance was obtainedfrom the Institutional Ethical Committee. Patients above 18 years of age who were willing to participate were included in the study. The data werecollected using specific data collection forms, and KAP toward medications of each patient was assessed using KAP questionnaire. Medicationadherence was analyzed using Morisky Medication Adherence Scale 4. Patient counseling about disease, medication, and lifestyle modification wasgiven, and the orally taking household drugs were segregated according to class and specific clinical uses.Results: Out of 129 patients, 58.1% were male. Out of 19 diseases encountered during the study, diabetes mellitus (32.56%) and hypertension(25.58%) were most prevalent. Majority of patients (63.57%) were prescribed with cardiovascular agents. Paracetamol was found as a commonhousehold drug. Sixty-nine percent of patients were procuring medication directly from the pharmacy and the remaining 31% were procuring theirmedication after consulting the physician. Mean scores of KAP in basal and endpoint assessment were compared using Student's t-test. p value wasfound to be &lt;0.000.Conclusion: The study tried to entitle the name of pharmacist as a patient educator who gives proper guidance to the patient and family membersabout the disease, domestic drug management, lifestyle modification, etc. The result of efficient patient counseling will be reflected on the properadherence of patient toward the medication and improved quality of life.Keywords: Knowledge, attitude and practice (KAP), Medication therapy management (MTM), Morisky medication adherence Scale – 4 (MMAS-4),patient education

Inhibition of mitochondrial respiration prevents BRAF-mutant melanoma brain metastasis

Melanoma patients carry a high risk of developing brain metastases, and improvements in survival are still measured in weeks or months. Durable disease control within the brain is impeded by poor drug penetration across the blood-brain barrier, as well as intrinsic and acquired drug resistance. Augmented mitochondrial respiration is a key resistance mechanism in BRAF-mutant melanomas but, as we show in this study, this dependence on mitochondrial respiration may also be exploited therapeutically. We first used high-throughput pharmacogenomic profiling to identify potentially repurposable compounds against BRAF-mutant melanoma brain metastases. One of the compounds identified was β-sitosterol, a well-tolerated and brain-penetrable phytosterol. Here we show that β-sitosterol attenuates melanoma cell growth in vitro and also inhibits brain metastasis formation in vivo. Functional analyses indicated that the therapeutic potential of β-sitosterol was linked to mitochondrial interference. Mechanistically, β-sitosterol effectively reduced mitochondrial respiratory capacity, mediated by an inhibition of mitochondrial complex I. The net result of this action was increased oxidative stress that led to apoptosis. This effect was only seen in tumor cells, and not in normal cells. Large-scale analyses of human melanoma brain metastases indicated a significant role of mitochondrial complex I compared to brain metastases from other cancers. Finally, we observed completely abrogated BRAF inhibitor resistance when vemurafenib was combined with either β-sitosterol or a functional knockdown of mitochondrial complex I. In conclusion, based on its favorable tolerability, excellent brain bioavailability, and capacity to inhibit mitochondrial respiration, β-sitosterol represents a promising adjuvant to BRAF inhibitor therapy in patients with, or at risk for, melanoma brain metastases