Triple-negative breast cancer (TNBC) remains a significant clinical challenge because of its high vascularity and metastatic and recurrent rates. Tumor angiogenesis is considered an important mediator in the regulation of tumor cell survival and metastasis in TNBC. Angiogenesis is induced by the binding of vascular endothelial growth factor to vascular endothelial growth factor receptor 2 (VEGFR2). Focal adhesion kinase (FAK) plays an important role in regulating various cell functions in normal and cancer cells. Previous studies have focused on investigating the function of endothelial FAK in tumor cell angiogenesis. However, the association between tumor FAK and VEGFR2 in tumor angiogenesis and the possible mechanisms of this remain unclear. In this study, we used a public database and human specimens to examine the association between FAK and VEGFR2. At the same time, we verified the association between FAK and VEGFR2 through several experimental methods, such as quantitative real-time polymerase chain reaction, Western blotting, and next-generation sequencing. In addition, we used the endothelial cell model, zebrafish, and xenograft animal models to investigate the role of FAK in TNBC angiogenesis. We found that FAK and VEGFR2 were positively correlated in patients with TNBC. VEGFR2 and several other angiogenesis-related genes were regulated by FAK. In addition, FAK regulated VEGFR2 and VEGF protein expression in TNBC cells. Functional assays showed that FAK knockdown inhibited endothelial tube formation and zebrafish angiogenesis. An animal model showed that FAK inhibitors could suppress tumor growth and tumor vascular formation. FAK promotes angiogenesis in TNBC cells by regulating VEGFR2 expression. Therefore, targeting FAK could be another antiangiogenic strategy for TNBC treatment.

Triple negative breast cancer (TNBC) displays higher risk of recurrence and distant metastasis. Due to absence of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), TNBC lacks clinically established targeted therapies. Therefore, understanding of the mechanism underlying the aggressive behaviors of TNBC is required for the design of individualized strategies and the elongation of overall survival duration. Here, we supported a positive correlation between β1 integrin and malignant behaviors such as cell migration, invasion, and drug resistance. We found that silencing of β1 integrin inhibited cell migration, invasion, and increased the sensitivity to anti-cancer drug. In contrast, activation of β1 integrin increased cell migration, invasion, and decreased the sensitivity to anti-cancer drug. Furthermore, we found that silencing of β1 integrin abolished Focal adhesion kinese (FAK) mediated cell survival. Overexpression of FAK could restore cisplatin-induced apoptosis in β1 integrin-depleted cells. Consistent to in vitro data, β1 integrin expression was also positively correlated with FAK (p = 0.031) in clinical tissue. More importantly, β1 integrin expression was significantly correlated with patient outcome. In summary, our study indicated that β1 integrin could regulate TNBC cells migration, invasion, drug sensitivity, and be a potential prognostic biomarker in TNBC patient survival.

Cancer cell metastasis is the main cause of death in patients with cancer. Many studies have investigated the biochemical factors that affect metastasis; however, the role of physical factors such as fluid shear stress (FSS) in tumorigenesis and metastasis have been less investigated. Triple-negative breast cancer (TNBC) has a higher incidence of lymph node invasion and distant metastasis than other subtypes of breast cancer. In this study, we investigated the influence of FSS in regulating the malignant behavior of TNBC cells. Our data demonstrate that low FSS promotes cell migration, invasion, and drug resistance, while high FSS has the opposite results; additionally, we found that these phenomena were regulated through focal adhesion kinase (FAK). Using immunohistochemistry staining, we show that FAK levels correlate with the nodal stage and that FAK is a significant independent predictor of overall survival in patients. Altogether, these data implicate FAK as a fluid mechano-sensor that regulates the cell motility induced by FSS and provide a strong rationale for cancer treatments that combine the use of anti-cancer drugs and strategies to modulate tumor interstitial fluid flow.

Triple-negative breast cancer (TNBC) is a special subtype of breast cancer in which several common diagnostic biomarkers are lost. Due to the loss of expression of receptors, treatment options for TNBC are limited. Therefore, finding safe and effective treatments for patients with TNBC is a major objective for clinicians. Previous studies suggested that cytokine-induced killer (CIK) cells may be beneficial for patients with a variety of tumor types. However, CIK therapy is not effective for all patients. In this study, we found that focal adhesion kinase (FAK), a non-receptor protein tyrosine kinase that regulates several cellular functions in different cells, has the potential to regulate tumor cells sensitized to CIK cells. Knockdown of FAK expression in TNBC cells or the treatment of TNBC cells with a FAK inhibitor followed by coculture with CIK cells increases death of TNBC cells, suggesting that FAK plays important roles in sensitizing tumor cells to CIK cells. This phenomenon could be regulated by a FAK-programmed death-ligand 1 (PD-L1)-related mechanism. Overall, our findings provide new insights into the cytotoxic effect of CIK cell therapy in TNBC treatment, and show that CIK cell therapy combined with FAK inhibitors may be a novel therapeutic strategy for patients with TNBC.