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B-Raf represents a critical physiological regulator of the Ras/RAF/MEK/ERK-pathway and a pharmacological target of growing clinical relevance, in particular in oncology. To understand how B-Raf itself is regulated, we combined mass spectrometry with genetic approaches to map its interactome in MCF-10A cells as well as in B-Raf deficient murine embryonic fibroblasts (MEFs) and B-Raf/Raf-1 double deficient DT40 lymphoma cells complemented with wildtype or mutant B-Raf expression vectors. Using a multi-protease digestion approach, we identified a novel ubiquitination site and provide a detailed B-Raf phospho-map. Importantly, we identify two evolutionary conserved phosphorylation clusters around T401 and S419 in the B-Raf hinge region. SILAC labelling and genetic/biochemical follow-up revealed that these clusters are phosphorylated in the contexts of oncogenic Ras, sorafenib induced Raf dimerization and in the background of the V600E mutation. We further show that the vemurafenib sensitive phosphorylation of the T401 cluster occurs in trans within a Raf dimer. Substitution of the Ser/Thr-residues of this cluster by alanine residues enhances the transforming potential of B-Raf, indicating that these phosphorylation sites suppress its signaling output. Moreover, several B-Raf phosphorylation sites, including T401 and S419, are somatically mutated in tumors, further illustrating the importance of phosphorylation for the regulation of this kinase.
Background
A significant number of oncological patients are heavily burdened by psychosocial stress. Doctors recommending or referring their patients to psycho-oncologists in the course of routine consultations can positively influence psycho-oncological care. The aim of this study was to analyze the frequency and predictors of such recommendations and to examine the use of these services by patients.
Methods
4,020 cancer patients (mean age 58 years; 51% women) were evaluated in a multicenter, cross-sectional study in Germany. Data was gathered about doctors’ referral practices, patients’ utilization of psycho-oncological care services, and disease-related symptoms. The PHQ-9 depression scale and the GAD-7 anxiety scale were used to measure psychological burden. Descriptive data analysis was conducted on the basis of subgroup comparisons and multivariable analysis was done using binary logistical regression.
Results
21.9% of the respondents reported having been given a recommendation or referral for psycho-oncological care by a doctor within the course of their cancer diagnosis and treatment. This comprises 29.5% of the patients identified by screening as being psychologically burdened. Nearly half of the patients who received a recommendation or referral (49.8%) acted on it. Predictors for seeking out psycho-oncological care included: patient desire (OR = 2.0), previous experience with psycho-oncological care (OR = 1.59), and female gender (OR = 1.57). Multivariable analysis indicated that patients’ level of psychological burden (depression, anxiety) had no effect on whether doctors gave them a recommendation or referral.
Conclusions
Along with examining the degree to which patients are burdened (e.g. using screening instruments), determining whether or not patients would like to receive psycho-oncological care is an important aspect of improving referral practices and, by extension, will allow important progress in the field of psycho-oncological care to be made.