Gene and protein expression and metabolic flux analysis reveals metabolic scaling in liver ex vivo and in vivo.

Metabolic scaling, the inverse correlation of metabolic rates to body mass, has been appreciated for more than 80 years. Studies of metabolic scaling have largely been restricted to mathematical modeling of caloric intake and oxygen consumption, and mostly rely on computational modeling. The possibility that other metabolic processes scale with body size has not been comprehensively studied. To address this gap in knowledge, we employed a systems approach including transcriptomics, proteomics, and measurement of in vitro and in vivo metabolic fluxes. Gene expression in livers of five species spanning a 30,000-fold range in mass revealed differential expression according to body mass of genes related to cytosolic and mitochondrial metabolic processes, and to detoxication of oxidative damage. To determine whether flux through key metabolic pathways is ordered inversely to body size, we applied stable isotope tracer methodology to study multiple cellular compartments, tissues, and species. Comparing C57BL/6 J mice with Sprague-Dawley rats, we demonstrate that while ordering of metabolic fluxes is not observed in in vitro cell-autonomous settings, it is present in liver slices and in vivo. Together, these data reveal that metabolic scaling extends beyond oxygen consumption to other aspects of metabolism, and is regulated at the level of gene and protein expression, enzyme activity, and substrate supply.

A review of the impact of energy balance on triple-negative breast cancer.

Cancer cells cannot proliferate without sufficient energy to generate biomass for rapid cell division, as well as to fuel their functions at baseline. For this reason, many recent observational and interventional studies have focused on increasing energy expenditure and/or reducing energy intake during and after cancer treatment. The impact of variance in diet composition and in exercise on cancer outcomes has been detailed extensively elsewhere and is not the primary focus of this review. Instead, in this translational, narrative review we examine studies of how energy balance impacts anticancer immune activation and outcomes in triple-negative breast cancer (TNBC). We discuss preclinical, clinical observational, and the few clinical interventional studies on energy balance in TNBC. We advocate for the implementation of clinical studies to examine how optimizing energy balance-through changes in diet and/or exercise-may optimize the response to immunotherapy in people with TNBC. It is our conviction that by taking a holistic approach that includes energy balance as a key factor to be considered during and after treatment, cancer care may be optimized, and the detrimental effects of cancer treatment and recovery on overall health may be minimized.

Perspectives of Historically Black College and University Advisors to Premedical Students During the COVID-19 Pandemic: A Qualitative Study.

Importance: Black students remain underrepresented in medicine despite national efforts to increase diversity in the physician workforce. Historically Black College and University (HBCU) students play a vital role in increasing representation in the workforce. Currently, there is a paucity of literature understanding the impact of COVID-19 on premedical students from HBCUs. Understanding the adverse impact of the pandemic on HBCU students is essential to inform strategies that promote holistic medical school admissions and increased diversity, equity, and inclusion in the medical workforce. Objective: To explore premedical advisors' perspectives on the impact of the COVID-19 pandemic on HBCU premedical students pursuing admission to medical school. Design, Setting, and Participants: In this qualitative study, semistructured interviews of HBCU premedical advisors were performed from March 2020 to March 2021. One-on-one interviews were conducted with 21 advisors with a depth of experience as advisors, varied educational backgrounds, and diverse geographic representation. Data analysis was performed from March 2021 to December 2021. Main Outcomes and Measures: The experiences of HBCU premedical students during the COVID-19 pandemic from the perspective of the premedical advisor. Results: Among the 21 participants, 13 (62%) were female, 15 (71%) were Black or African American, 11 (52%) had a doctorate degree, and 7 (33%) had more than 10 years of experience as advisors. Participants described 3 major themes: (1) balancing academic responsibilities with family demands; (2) distraction, disruption, and isolation in the virtual learning environment; and (3) harmful impact of new stressors for HBCU applicants in the medical school admissions process. Conclusions and Relevance: In this qualitative study of HBCU advisors to premedical students, advisors described how the COVID-19 pandemic adversely affected undergraduate HBCU premedical students; students faced family hardships, challenges with virtual learning, and uncertainty in the medical school admissions process. These findings suggest that medical schools should continue to create direct interventions to address the challenges that HBCU students faced during the height of the pandemic and as longitudinal consequences of the pandemic. Addressing these issues may improve physician workforce representation and promote more equitable patient care for underserved communities disproportionately affected by COVID-19 and other health disparities.

Corrigendum: Gut bacteria regulate the pathogenesis of Huntington's disease in Drosophila model.

[This corrects the article DOI: 10.3389/fnins.2022.902205.].

Gut Bacteria Regulate the Pathogenesis of Huntington's Disease in Drosophila Model.

Changes in the composition of gut microbiota are implicated in the pathogenesis of several neurodegenerative disorders. Here, we investigated whether gut bacteria affect the progression of Huntington's disease (HD) in transgenic Drosophila melanogaster (fruit fly) models expressing full-length or N-terminal fragments of human mutant huntingtin (HTT) protein. We find that elimination of commensal gut bacteria by antibiotics reduces the aggregation of amyloidogenic N-terminal fragments of HTT and delays the development of motor defects. Conversely, colonization of HD flies with Escherichia coli (E. coli), a known pathobiont of human gut with links to neurodegeneration and other morbidities, accelerates HTT aggregation, aggravates immobility, and shortens lifespan. Similar to antibiotics, treatment of HD flies with small compounds such as luteolin, a flavone, or crocin a beta-carotenoid, ameliorates disease phenotypes, and promotes survival. Crocin prevents colonization of E. coli in the gut and alters the levels of commensal bacteria, which may be linked to its protective effects. The opposing effects of E. coli and crocin on HTT aggregation, motor defects, and survival in transgenic Drosophila models support the involvement of gut-brain networks in the pathogenesis of HD.

A precision medicine approach to metabolic therapy for breast cancer in mice.

Increasing evidence highlights approaches targeting metabolism as potential adjuvants to cancer therapy. Sodium-glucose transport protein 2 (SGLT2) inhibitors are the newest class of antihyperglycemic drugs. To our knowledge, SGLT2 inhibitors have not been applied in the neoadjuvant setting as a precision medicine approach for this devastating disease. Here, we treat lean breast tumor-bearing mice with the SGLT2 inhibitor dapagliflozin as monotherapy and in combination with paclitaxel chemotherapy. We show that dapagliflozin enhances the efficacy of paclitaxel, reducing tumor glucose uptake and prolonging survival. Further, the ability of dapagliflozin to enhance the efficacy of chemotherapy correlates with its effect to reduce circulating insulin in some but not all breast tumors. Our data suggest a genetic signature for breast tumors more likely to respond to dapagliflozin in combination with paclitaxel. In the current study, tumors driven by mutations upstream of canonical insulin signaling pathways responded to this combined treatment, whereas tumors driven by mutations downstream of canonical insulin signaling did not. These data demonstrate that dapagliflozin enhances the response to chemotherapy in mice with breast cancer and suggest that patients with driver mutations upstream of canonical insulin signaling may be most likely to benefit from this neoadjuvant approach.

Insulin and cancer: a tangled web.

For a century, since the pioneering work of Otto Warburg, the interwoven relationship between metabolism and cancer has been appreciated. More recently, with obesity rates rising in the U.S. and worldwide, epidemiologic evidence has supported a link between obesity and cancer. A substantial body of work seeks to mechanistically unpack the association between obesity, altered metabolism, and cancer. Without question, these relationships are multifactorial and cannot be distilled to a single obesity- and metabolism-altering hormone, substrate, or factor. However, it is important to understand the hormone-specific associations between metabolism and cancer. Here, we review the links between obesity, metabolic dysregulation, insulin, and cancer, with an emphasis on current investigational metabolic adjuncts to standard-of-care cancer treatment.