Lysosomal enzyme trafficking factor LYSET enables nutritional usage of extracellular proteins.

Mammalian cells can generate amino acids through macropinocytosis and lysosomal breakdown of extracellular proteins, which is exploited by cancer cells to grow in nutrient-poor tumors. Through genetic screens in defined nutrient conditions, we characterized LYSET, a transmembrane protein (TMEM251) selectively required when cells consume extracellular proteins. LYSET was found to associate in the Golgi with GlcNAc-1-phosphotransferase, which targets catabolic enzymes to lysosomes through mannose-6-phosphate modification. Without LYSET, GlcNAc-1-phosphotransferase was unstable because of a hydrophilic transmembrane domain. Consequently, LYSET-deficient cells were depleted of lysosomal enzymes and impaired in turnover of macropinocytic and autophagic cargoes. Thus, LYSET represents a core component of the lysosomal enzyme trafficking pathway, underlies the pathomechanism for hereditary lysosomal storage disorders, and may represent a target to suppress metabolic adaptations in cancer.

Factors associated with changes in exercise behaviors during the COVID-19 pandemic.

PURPOSE: There is limited information on how the COVID-19 pandemic has changed health behaviors among cancer patients. We examined changes in exercise behaviors since the pandemic and identified characteristics associated with these changes among cancer patients. METHODS: Cancer patients (n = 1,210) completed a survey from August to September 2020 to assess COVID-19 pandemic-related changes in health behaviors and psychosocial factors. Patients were categorized into three groups: exercising less, exercising did not change, and exercising more. Patient characteristics were compared by exercise groups. RESULTS: One-third of the patients reported a decreased amount of regular exercise, while 10% reported exercising more during the pandemic. Patients who exercised less were more likely to be unemployed/retired and have poor health status and psychosocial stressors such as disruptions in daily life while less likely to be former smokers (all p < 0.05). In contrast, patients who exercised more were younger, had stage IV diagnosis, and also reported disruptions in daily life (all p < 0.05). Patients who were living in rural areas were also more likely not to experience changes in exercise habits (all p < 0.05), although rural-urban status was not identified as a strong predictor. CONCLUSION: A significant proportion of cancer patients experienced changes in exercise habits, especially exercising less, during the first 6 months of the COVID-19 pandemic. Age, employment status, tumor stage, health status, smoking status, and psychosocial factors were associated with changes in exercise behaviors. Our results highlight the importance of promoting physical activity guidelines for cancer survivorship during the COVID-19 pandemic and may help improve the identification of cancer patients susceptible to exercising less.

Impact of the COVID-19 pandemic on rural and urban cancer patients' experiences, health behaviors, and perceptions.

PURPOSE: The COVID-19 pandemic has disrupted many facets of life. We evaluated pandemic-related health care experiences, COVID-19 prevention behaviors and measures, health behaviors, and psychosocial outcomes among rural and urban cancer patients. METHODS: Among 1,472 adult cancer patients, who visited Huntsman Cancer Institute in the past 4 years and completed a COVID-19 survey (August-September 2020), we assessed the impact of the pandemic on medical appointments, prevention/health behaviors, and psychosocial factors, stratified by urbanicity. FINDINGS: Mean age was 61 years, with 52% female, 97% non-Hispanic White, and 27% were residing in rural areas. Rural versus urban patients were more likely to be older, not employed, uninsured, former/current smokers, consume alcohol, and have pandemic-related changes/cancellations in surgery appointments (all P<.05). Changes/cancellations in other health care access (eg, doctor's visits) were also common, particularly among urban patients. Urban versus rural patients were more likely to socially distance, use masks and hand sanitizer, and experience changes in exercise habits and in their daily lives (all P<.05). Less social interaction and financial stress were common among cancer patients but did not differ by urbanicity. CONCLUSIONS: These findings suggest that the COVID-19 pandemic had a substantial impact on cancer patients, with several challenges specific to rural patients. This comprehensive study provides unique insights into the first 6 months of COVID-19 pandemic-related experiences and continuity of care among rural and urban cancer patients predominantly from Utah. Further research is needed to better characterize the pandemic's short- and long-term effects on rural and urban cancer patients and appropriate interventions.

Synergistic Adverse Effects of Azithromycin and Hydroxychloroquine on Human Cardiomyocytes at a Clinically Relevant Treatment Duration.

Adverse effects of drug combinations and their underlying mechanisms are highly relevant for safety evaluation, but often not fully studied. Hydroxychloroquine (HCQ) and azithromycin (AZM) were used as a combination therapy in the treatment of COVID-19 patients at the beginning of the pandemic, leading to higher complication rates in comparison to respective monotherapies. Here, we used human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) to systematically investigate the effects of HCQ, AZM, and their combination on the structure and functionality of cardiomyocytes, and to better understand the underlying mechanisms. Our results demonstrate synergistic adverse effects of AZM and HCQ on electrophysiological and contractile function of iPSC-CMs. HCQ-induced prolongation of field potential duration (FPDc) was gradually increased during 7-day treatment period and was strongly enhanced by combination with AZM, although AZM alone slightly shortened FPDc in iPSC-CMs. Combined treatment with AZM and HCQ leads to higher cardiotoxicity, more severe structural disarrangement, more pronounced contractile dysfunctions, and more elevated conduction velocity, compared to respective monotreatments. Mechanistic insights underlying the synergistic effects of AZM and HCQ on iPSC-CM functionality are provided based on increased cellular accumulation of HCQ and AZM as well as increased Cx43- and Nav1.5-protein levels.