Outcomes and prognostic factors for women with breast cancer in Malawi.

BACKGROUND: Breast cancer incidence in sub-Saharan Africa (SSA) is increasing, and SSA has the highest age-standardized breast cancer mortality rate worldwide. However, high-quality breast cancer data are limited in SSA. MATERIALS AND METHODS: We examined breast cancer patient and tumor characteristics among women in Lilongwe, Malawi and evaluated risk factor associations with patient outcomes. We consecutively enrolled 100 women ≥ 18 years with newly diagnosed, pathologically confirmed breast cancer into a prospective longitudinal cohort with systematically assessed demographic data, HIV status, and clinical characteristics. Tumor subtypes were further determined by immunohistochemistry, overall survival (OS) was estimated using Kaplan-Meier methods, and hazards ratios (HR) were calculated by Cox proportional hazard analyses. RESULTS: Of the 100 participants, median age was 49 years, 19 were HIV-positive, and 75 presented with late stage (III/IV) disease. HER2-enriched and triple-negative/basal-like subtypes represented 17% and 25% tumors, respectively. One-year OS for the cohort was 74% (95% CI 62-83%). Multivariable analyses revealed mortality was associated with HIV (HR, 5.15; 95% CI 1.58-16.76; p = 0.006), stage IV disease (HR, 8.86; 95% CI 1.07-73.25; p = 0.043), and HER2-enriched (HR, 7.46; 95% CI 1.21-46.07; p = 0.031), and triple-negative subtypes (HR, 7.80; 95% CI 1.39-43.69; p = 0.020). CONCLUSION: Late stage presentation, HER2-enriched and triple-negative subtypes, and HIV coinfection were overrepresented in our cohort relative to resource-rich settings and were associated with mortality. These findings highlight robust opportunities for population- and patient-level interventions across the entire cascade of care to improve breast cancer outcomes in low-income countries in SSA.

The Ephrin-A1/EPHA2 Signaling Axis Regulates Glutamine Metabolism in HER2-Positive Breast Cancer.

Dysregulation of receptor tyrosine kinases (RTK) contributes to cellular transformation and cancer progression by disrupting key metabolic signaling pathways. The EPHA2 RTK is overexpressed in aggressive forms of breast cancer, including the HER2(+) subtype, and correlates with poor prognosis. However, the role of EPHA2 in tumor metabolism remains unexplored. In this study, we used in vivo and in vitro models of HER2-overexpressing breast cancer to investigate the mechanisms by which EPHA2 ligand-independent signaling promotes tumorigenesis in the absence of its prototypic ligand, ephrin-A1. We demonstrate that ephrin-A1 loss leads to upregulated glutamine metabolism and lipid accumulation that enhanced tumor growth. Global metabolic profiling of ephrin-A1-null, HER2-overexpressing mammary tumors revealed a significant increase in glutaminolysis, a critical metabolic pathway that generates intermediates for lipogenesis. Pharmacologic inhibition of glutaminase activity reduced tumor growth in both ephrin-A1-depleted and EPHA2-overexpressing tumor allografts in vivo Mechanistically, we show that the enhanced proliferation and glutaminolysis in the absence of ephrin-A1 were attributed to increased RhoA-dependent glutaminase activity. EPHA2 depletion or pharmacologic inhibition of Rho, glutaminase, or fatty acid synthase abrogated the increased lipid content and proliferative effects of ephrin-A1 knockdown. Together, these findings highlight a novel, unsuspected connection between the EPHA2/ephrin-A1 signaling axis and tumor metabolism, and suggest potential new therapeutic targets in cancer subtypes exhibiting glutamine dependency. Cancer Res; 76(7); 1825-36. ©2016 AACR.

LIM-Only Protein 4 (LMO4) and LIM Domain Binding Protein 1 (LDB1) Promote Growth and Metastasis of Human Head and Neck Cancer (LMO4 and LDB1 in Head and Neck Cancer).

Squamous cell carcinoma of the head and neck (HNSCC) accounts for more than 300,000 deaths worldwide per year as a consequence of tumor cell invasion of adjacent structures or metastasis. LIM-only protein 4 (LMO4) and LIM-domain binding protein 1 (LDB1), two directly interacting transcriptional adaptors that have important roles in normal epithelial cell differentiation, have been associated with increased metastasis, decreased differentiation, and shortened survival in carcinoma of the breast. Here, we implicate two LDB1-binding proteins, single-stranded binding protein 2 (SSBP2) and 3 (SSBP3), in controlling LMO4 and LDB1 protein abundance in HNSCC and in regulating specific tumor cell functions in this disease. First, we found that the relative abundance of LMO4, LDB1, and the two SSBPs correlated very significantly in a panel of human HNSCC cell lines. Second, expression of these proteins in tumor primaries and lymph nodes involved by metastasis were concordant in 3 of 3 sets of tissue. Third, using a Matrigel invasion and organotypic reconstruct assay, CRISPR/Cas9-mediated deletion of LDB1 in the VU-SCC-1729 cell line, which is highly invasive of basement membrane and cellular monolayers, reduced tumor cell invasiveness and migration, as well as proliferation on tissue culture plastic. Finally, inactivation of the LDB1 gene in these cells decreased growth and vascularization of xenografted human tumor cells in vivo. These data show that LMO4, LDB1, and SSBP2 and/or SSBP3 regulate metastasis, proliferation, and angiogenesis in HNSCC and provide the first evidence that SSBPs control LMO4 and LDB1 protein abundance in a cancer context.

Genetic and pharmacologic inhibition of EPHA2 promotes apoptosis in NSCLC.

Genome-wide analyses determined previously that the receptor tyrosine kinase (RTK) EPHA2 is commonly overexpressed in non-small cell lung cancers (NSCLCs). EPHA2 overexpression is associated with poor clinical outcomes; therefore, EPHA2 may represent a promising therapeutic target for patients with NSCLC. In support of this hypothesis, here we have shown that targeted disruption of EphA2 in a murine model of aggressive Kras-mutant NSCLC impairs tumor growth. Knockdown of EPHA2 in human NSCLC cell lines reduced cell growth and viability, confirming the epithelial cell autonomous requirements for EPHA2 in NSCLCs. Targeting EPHA2 in NSCLCs decreased S6K1-mediated phosphorylation of cell death agonist BAD and induced apoptosis. Induction of EPHA2 knockdown within established NSCLC tumors in a subcutaneous murine model reduced tumor volume and induced tumor cell death. Furthermore, an ATP-competitive EPHA2 RTK inhibitor, ALW-II-41-27, reduced the number of viable NSCLC cells in a time-dependent and dose-dependent manner in vitro and induced tumor regression in human NSCLC xenografts in vivo. Collectively, these data demonstrate a role for EPHA2 in the maintenance and progression of NSCLCs and provide evidence that ALW-II-41-27 effectively inhibits EPHA2-mediated tumor growth in preclinical models of NSCLC.