The cytosolic branched chain aminotransferase (BCATc) protein has been found to be highly expressed in breast cancer subtypes, including triple negative breast cancer (TNBC), compared with normal breast tissue. The catabolism of branched-chain amino acids (BCAAs) by BCATc leads to the production of glutamate and key metabolites which further drive the TCA cycle, important for cellular metabolism and growth. Upregulation of BCATc has been associated with increased cell proliferation, cell cycle progression and metastasis in several malignancies including breast, gliomas, ovarian and colorectal cancer but the underlying mechanisms are unclear. As nutrient levels of BCAAs, substrates of BCATc, regulate the PI3K/Akt pathway we hypothesized that increased expression of BCATc would contribute to tumour cell growth through upregulation of the insulin/IGF-1 signalling pathway. This pathway is known to potentiate proliferation and metastasis of malignant cells through the activation of PI3K/Akt and the RAS/ERK signalling cascades. Here we show that knockdown of BCATc significantly reduced insulin and IGF-1-mediated proliferation, migration and invasion of TNBC cells. An analysis of this pathway showed that when overexpressed BCATc regulates proliferation through the PI3K/Akt axis, whilst simultaneously attenuating the Ras/Erk pathway indicating that BCATc acts as a conduit between these two pathways. This ultimately led to an increase in FOXO3a, a key regulator of cell proliferation and Nrf2, which mediates redox homeostasis. Together this data indicates that BCATc regulates TNBC cell proliferation, migration and invasion through the IGF-1/insulin PI3K/Akt pathway, culminating in the upregulation of FOXO3a and Nrf2, pointing to a novel therapeutic target for breast cancer treatment.

IntroductionMany breast cancer survivors report an inability to fully participate in activities of daily living after completing cancer treatment. Reduced activity participation is linked to negative consequences for individuals (eg, depression, reduced quality of life) and society (reduced workforce participation). There is currently a lack of evidence-based interventions that directly foster cancer survivors’ optimal participation in life roles and activities. Pilot study data suggest rehabilitation interventions based on behavioural activation (BA) and problem-solving treatment (PST) can facilitate post-treatment role resumption among breast cancer survivors.Methods and analysisThis protocol describes a multisite randomised controlled trial comparing a 4-month long, nine-session BA and PST-informed rehabilitation intervention (BA/PS) against a time-matched, attention control condition. The overall objective is to assess the efficacy of BA/PS for enhancing breast cancer survivors’ activity participation and quality of life over time. A total of 300 breast cancer survivors reporting participation restrictions after completing curative treatment for stage 1–3 breast cancer within the past year will be recruited across two sites (Dartmouth-Hitchcock Medical Center and University of Alabama at Birmingham). Assessments are collected on enrolment (T1) and 8 (T2), 20 (T3) and 44 (T4) weeks later.Ethics and disseminationStudy procedures are approved by the Committee for the Protection of Human Subjects at Dartmouth College, acting as the single Institutional Review Board of record for both study sites (STUDY 00031380). Results of the study will be presented at national meetings and submitted for publication in peer-reviewed journals.Trial registration numberNCT03915548; Pre-results.

106 Background: Costs for cancer patients are not all monetary. For patients with limited life expectancy, such as metastatic breast cancer (MBC) patients, time spent in the hospital or clinic setting can become burdensome. The goal was to evaluate time spent on healthcare among patients receiving treatment for MBC. Methods: This survey-based, cross-sectional study included women ≥18 years with MBC who received treatment at two academic medical centers in Alabama from 2017-2019. Questions regarding employment status, MBC-related hours missed from work, and time spent on healthcare-related activities were used to quantify lost productivity and time. Descriptive statistics included means and standard deviations (SD) or medians and interquartile ranges (IQR) for continuous variables and frequencies for categorical variables. Effect sizes were calculated using Cohen’s d or Cramer’s V. Results: We surveyed 83 female MBC patients with a median age of 59 years (IQR 50-66). Among all respondents, 34% were African American, 41% held a college degree, and 52% had a household income of < $40,000. Patients spent a median 60 minutes (IQR 30-110) traveling from their home to clinic and a median 120 minutes (IQR 60-180) receiving care at a clinic visit. Though not statistically significant, modest differences were found for patients with differing insurance types in travel time. Patients with Medicare had the shortest travel time (median 45 minutes [IQR 30-75]) compared to Medicaid (60 minutes [IQR 60-80]) and private insurance (60 minutes [IQR 30-120]; d = .06).). Patients spent a median 30 minutes (IQR 0-60) on cancer care related activities outside of a clinic visit. Most patients were retired (31%); however, 15% worked full-time, 6% worked part-time, and 20% were on disability. For working women, a median of 8 hours (IQR 1-11) were missed from work in the week. Conclusions: This study highlights productivity losses uncaptured by current patient healthcare cost calculations. Further work is needed to identify and minimize these additional patient costs related to lost productivity during cancer treatment.