Adaptive stimulation of macropinocytosis overcomes aspartate limitation in cancer cells under hypoxia.

Stress-adaptive mechanisms enable tumour cells to overcome metabolic constraints under nutrient and oxygen shortage. Aspartate is an endogenous metabolic limitation under hypoxic conditions, but the nature of the adaptive mechanisms that contribute to aspartate availability and hypoxic tumour growth are poorly understood. Here we identify GOT2-catalysed mitochondrial aspartate synthesis as an essential metabolic dependency for the proliferation of pancreatic tumour cells under hypoxic culture conditions. In contrast, GOT2-catalysed aspartate synthesis is dispensable for pancreatic tumour formation in vivo. The dependence of pancreatic tumour cells on aspartate synthesis is bypassed in part by a hypoxia-induced potentiation of extracellular protein scavenging via macropinocytosis. This effect is mutant KRAS dependent, and is mediated by hypoxia-inducible factor 1 (HIF1A) and its canonical target carbonic anhydrase-9 (CA9). Our findings reveal high plasticity of aspartate metabolism and define an adaptive regulatory role for macropinocytosis by which mutant KRAS tumours can overcome nutrient deprivation under hypoxic conditions.

Targeting the α4-α5 interface of RAS results in multiple levels of inhibition.

Generation of RAS-targeted therapeutics has long been considered a "holy grail" in cancer research. However, a lack of binding pockets on the surface of RAS and its picomolar affinity for guanine nucleotides have made isolation of inhibitors particularly challenging. We recently described a monobody, termed NS1, that blocks RAS signaling and oncogenic transformation. NS1 binds to the α4-ß6-α5 interface of H-RAS and K-RAS thus preventing RAS dimerization and nanoclustering, which in turn prevents RAS-stimulated dimerization and activation of RAF. Interestingly, NS1 reduces interaction of oncogenic K-RAS, but not H-RAS, with RAF and reduces K-RAS plasma membrane localization. Here, we show that these isoform specific effects of NS1 on RAS:RAF are due to the distinct hypervariable regions of RAS isoforms. NS1 inhibited wild type RAS function by reducing RAS GTP levels. These findings reveal that NS1 disrupts RAS signaling through a mechanism that is more complex than simply inhibiting RAS dimerization and nanoclustering.

Clustering of Toxoplasma gondii Infections Within Families of Congenitally Infected Infants.

BACKGROUND: Family clusters and epidemics of toxoplasmosis in North, Central, and South America led us to determine whether fathers of congenitally infected infants in the National Collaborative Chicago-Based Congenital Toxoplasmosis Study (NCCCTS) have a high incidence of Toxoplasma gondii infection. METHODS: We analyzed serum samples collected from NCCCTS families between 1981 and 2013. Paternal serum samples were tested for T. gondii antibodies with immunoglobulin (Ig) G dye test and IgM enzyme-linked immunosorbent assay. Additional testing of paternal serum samples was performed with differential-agglutination and IgG avidity tests when T. gondii IgG and IgM results were positive and serum samples were collected by the 1-year visit of the congenitally infected child. Prevalence of paternal seropositivity and incidence of recent infection were calculated. We analyzed whether certain demographics, maternal parasite serotype, risk factors, or maternal/infant clinical manifestations were associated with paternal T. gondii infection status. RESULTS: Serologic testing revealed a high prevalence (29 of 81; 36%) of T. gondii infection in fathers, relative to the average seropositivity rate of 9.8% for boys and men aged 12-49 years in the United States between 1994 and 2004 (P < .001). Moreover, there was a higher-than-expected incidence of recent infections among fathers with serum samples collected by the 1-year visit of their child (6 of 45; 13%; P < .001). No demographic patterns or clinical manifestations in mothers or infants were associated with paternal infections, except for sandbox exposure. CONCLUSIONS: The high prevalence of chronic and incidence of recent T. gondii infections in fathers of congenitally infected children indicates that T. gondii infections cluster within families in North America. When a recently infected person is identified, family clustering and community risk factors should be investigated for appropriate clinical management.

Use of complementaryand alternative therapies among rural TB patients in Nalgonda, Andhra Pradesh: a qualitative study.

BACKGROUND: A considerable number of studies have been conducted on health seeking behaviour of TB patients in different parts of the world. However, these studies largely ignored the prevalence and use of complementary and alternative medical practices (CAM) among TB patients. This present study was prompted by the recognition that, an understanding of different factors influencing CAM use in a medically pluralistic setting has important implications for providing patient-centred comprehensive care, and improving the quality of life for TB patients. AIM: The objective of the study was to explore the reasons and motivations for the use of Complementary and Alternative Medicine (CAM) therapies among rural TB patients. METHODS: A sample of 110 respondents were recruited purposively from two selected rural TB units at Yadagirigutta and Chintapally in Nalgonda district in Andhra Pradesh (A.P.). Semi-structured interview schedule and case study methods were used for the collection of primary data. A qualitative content analysis method was employed to analyse and interpret the data. RESULTS: TB patients employed a variety of alternative therapies such as massage, prayer, amulets, diet, faith or spiritual healing, restriction in alcohol consumption and smoking, abstinence from sex, and herbal teas as an adjunct to biomedical TB treatment. Engaging in alternative medical practices resulted in a sense control and relief from physical and psychological suffering and trauma associated TB illness. CONCLUSION: There is a need on the part of the health care professionals and health policy managers to gain insight into the motivations and reasons for CAM use among the TB patients. Such a shift in thinking will impact on reducing non-compliance, and identifying and dealing with unmet needs of patients which are seen as major deterrents to successful TB control programmes.

Psychosocial trauma of diagnosis: a qualitative study on rural TB patients' experiences in Nalgonda district, Andhra Pradesh.

BACKGROUND: The current tuberculosis (TB) control strategy in India largely ignores psychosocial needs of the patients. The present study was prompted by the recognition that, if TB treatment is to be culturally sensitive and effective, the psychosocial problems and issues need to be recognized and addressed. AIMS: The main aim of this study was to explore psychosocial problems and issues among rural patients being diagnosed with TB. METHODS: 110 respondents who had known about their TB diagnosis less than two months prior to conducting the interviews were recruited purposively from two selected rural TB units at Yadagirigutta and Chintapally in Nalgonda district in Andhra Pradesh (A.P.). Semi-structured interview schedule was used for the collection of primary data. A qualitative content analysis method was employed to analyze and interpret the data. Data analysis was carried out following multi-step procedure that consisted of data reduction, coding and identification of dominant themes. RESULTS: The diagnosis of TB was generally seen as a shocking and demoralizing experience, and raised a host of social and psychological problems among the patients. Six prominent themes emerged from the in-depth interviews with the respondents: i) worry, ii) disbelief, iii) embarrassment, iv) fear of death, v) fate, and vi) relief. CONCLUSION: Effective care for TB requires a much broader approach beyond focusing on anti-tuberculosis drugs and diagnostic techniques. For medical care to be most effective and acceptable to patients, general practitioners should treat both illness and disease in their patients at the same time. Knowledge of the nature of psychosocial problems is crucial for the design of new approaches and methods to improve the quality of life of TB patients.