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Breast cancers with HER2 amplification have a poorer prognosis than the luminal phenotypes. TRAIL activates apoptosis upon binding its receptors in some but not all breast cancer cell lines. Herein, we investigated the expression pattern of c-FLIP(L) in a cohort of 251 invasive breast cancer tissues and explored its potential role in TRAIL resistance. C-FLIP(L) was relatively high-expressed in HER2-positive breast cancer in comparison with other molecular subtypes, co-expressed with TRAIL death receptors, and inversely correlated with the apoptosis index. Downregulation of c-FLIP(L) sensitized SKBR3 cells to TRAIL-induced apoptosis in a concentration- and time-dependent manner and enhanced the activities and cleavages of caspase-8 and caspase-3, without altering the surface expression of death receptors. Together, our results indicate that c-FLIP(L) promotes TRAIL resistance and inhibits caspase-3 and caspase-8 activation in HER2-positive breast cancer. [ABSTRACT FROM AUTHOR]

Objectives: Data on breast squamous cell carcinoma (SCC) are rare. The aim of this study was to analyze the clinical characteristics and to explore the rational treatment of patients with breast SCC. Patients and methods: We conducted a retrospective review of breast SCC cases treated at our center from 1966 to 2014. The majority of these patients received primary surgery followed by adjuvant chemoradiotherapy, whilst four elderly patients had lumpectomy only. Results: Patients with breast SCC were usually women, and large masses, large proportion of early stage disease, low levels of estrogen receptor expression, less frequent axillary lymph nodes involvement, and unfavorable prognosis were common. The 5-year overall survival and progression-free survival of all patients were 67.2% and 57.8%, respectively. Axillary nodal involvement was a significant prognostic factor for survival. Conclusion: The current results indicated that breast SCC is clinically aggressive and the outcomes were poor. Distant metastasis was the main failure pattern. New strategies will be needed because of the poor outcomes. [ABSTRACT FROM AUTHOR]

The oncogenic receptor tyrosine kinase AXL is overexpressed in cancer and plays an important role in carcinomas of multiple organs. However, the mechanisms of AXL overexpression in cancer remain unclear. In this study, using HEK293T, Panc-1, and Panc-28 cells, and samples of human pancreatic intraepithelial neoplasia (PanIN), along with several biochemical approaches and immunofluorescence microscopy analyses, we sought to investigate the mechanisms that regulate AXL expression in pancreatic ductal adenocarcinoma (PDAC). We found that AXL interacts with hematopoietic progenitor kinase 1 (HPK1) and demonstrate that HPK1 down-regulates AXL and decreases its half-life. The HPK1-mediated AXL degradation was inhibited by the endocytic pathway inhibitors leupeptin, baflomycin A1, and monensin. HPK1 accelerated the movement of AXL from the plasma membrane to endosomes in pancreatic cancer cells treated with the AXL ligand growth arrest-specific 6 (GAS6). Moreover, HPK1 increased the binding of AXL to Cbl proto-oncogene (c-Cbl); promoted AXL ubiquitination; decreased AXL-mediated signaling, including phospho-AKT and phospho-ERK signaling; and decreased the invasion capability of PDAC cells. Importantly, we show that AXL expression inversely correlates with HPK1 expression in human PanINs and that patients whose tumors have low HPK1 and high AXL expression levels have shorter survival than those with low AXL or high HPK1 expression (P < 0.001). Our results suggest that HPK1 is a tumor suppressor that targets AXL for degradation via the endocytic pathway. HPK1 loss of function may contribute to AXL overexpression and thereby enhance AXL-dependent downstream signaling and tumor invasion in PDAC. [ABSTRACT FROM AUTHOR]

Objectives MAP4K5 plays an important role in regulating a range of cellular responses and is involved in Wnt signaling in hematopoietic cells. However, its functions in human malignancies have not been studied. The major objectives of this study are to examine the expression, functions and clinical significance of MAP4K5 in pancreatic ductal adenocarcinoma (PDAC). Materials and Methods The expression levels of MAP4K5, E-cadherin, vimentin, and carboxylesterase 2 (CES2) were examined by immunohistochemistry in 105 PDAC and matched non-neoplastic pancreas samples from our institution. The RNA sequencing data of 112 PDAC patients were downloaded from the TCGA data portal. Immunoblotting and RNA sequencing analysis were used to examine the expression of MAP4K5 and E-cadherin in pancreatic cancer cell lines. The effect of knockdown MAP4K5 using siRNA on the expression of CDH1 and vimentin were examined by Real-time RT-PCR in Panc-1 and AsPC-1 cells. Statistical analyses were performed using IBM SPSS Statistics. Results MAP4K5 protein is expressed at high levels specifically in the pancreatic ductal cells of 100% non-neoplastic pancreas samples, but is decreased or lost in 77.1% (81/105) of PDAC samples. MAP4K5-low correlated with the loss of E-cadherin (P = 0.001) and reduced CES2 expression (P = 0.002) in our patient populations. The expression levels of MAP4K5 mRNA directly correlated with the expression levels of CDH1 mRNA (R = 0.2490, P = 0.008) in the second cohort of 112 PDAC patients from The Cancer Genome Atlas (TCGA) RNA-seq dataset. Similar correlations between the expression of MAP4K5 and Ecadherin were observed both at protein and mRNA levels in multiple pancreatic cancer cell lines. Knockdown MAP4K5 led to decreased CDH1 mRNA expression in Panc-1 and AsPC-1 cells. MAP4K5-low correlated significantly with reduced overall survival and was an independent prognosticator in patients with stage II PDAC. Conclusions MAP4K5 expression is decreased or lost in majority of PDACs. The strong associations between low MAP4K5 expression and loss of E-cadherin, reduced CES2 expression and decreased overall survival may suggest an important role of MAP4K5 in epithelial-to-mesenchymal transition, chemotherapy resistance and tumor progression in pancreatic cancer. Targeting impaired MAP4K5 signaling may represent a new therapeutic strategy for pancreatic cancer. [ABSTRACT FROM AUTHOR]