E3 ubiquitin ligase Hakai regulates cell growth and invasion, and increases the chemosensitivity to cisplatin in non­small­cell lung cancer cells.

Hakai was originally identified as an E3 ubiquitin ligase of the E­cadherin complex implicated in cell adhesion and invasion. Recently, emerging evidence has strongly suggested that Hakai serves a pivotal role in the tumorigenesis of certain tumors. However, the role of Hakai in non­small­cell lung cancer (NSCLC) and its underlying molecular mechanism have not been clarified. In the present study, it was observed that Hakai was highly expressed in NSCLC cell lines compared with human normal bronchial epithelial cells, and transfection with Hakai small interfering RNA significantly inhibited the growth of A549 and NCI­H460 NSCLC cells. In addition, the inhibition of Hakai suppressed NSCLC cell migration and invasion through upregulation of E­cadherin and downregulation of N­cadherin. Notably, it was also revealed that knockdown of Hakai led to a decrease in the expression of phosphorylated AKT (Ser473), and a significant enhancement of chemosensitivity to cisplatin was observed following Hakai suppression. In conclusion, the present study demonstrated for the first time that knockdown of Hakai inhibited the proliferation, migration and invasion of NSCLC cells, and sensitized NSCLC cells to cisplatin. Thus, Hakai may serve as a potential therapeutic target for the treatment of NSCLC.

YSA-conjugated mesoporous silica nanoparticles effectively target EphA2-overexpressing breast cancer cells.

PURPOSE: Neoadjuvant chemotherapy is commonly used to treat patients with locally advanced breast cancer and a common option for primary operable disease. However, systemic toxicity including cardiotoxicity and inefficient delivery are significant challenges form any chemotherapeutics. The development of targeted treatments that lower the risk of toxicity has, therefore, become an active area of research in the field of novel cancer therapeutics. Mesoporous silica nanoparticles (MSNs) have attracted significant attention as efficient drug delivery carriers, due to their high surface area and tailorable mesoporous structures. Eph receptors are the largest receptor tyrosine kinase family, which are divided into the A- and the B-type. Eph receptors play critical roles in embryonic development and human diseases including cancer. EphA2 is expressed in breast cancer cells and has roles in carcinogenesis, progression and prognosis of breast cancer. METHODS: A homing peptide with the sequence YSAYPDSVPMMSK (YSA) that binds specifically to EphA2 was used to functionalize MSN. We focus on a novel EphA2-targeted delivery MSN system for breast cancer cells. RESULTS: We show that the EphA2 receptor is differentially expressed in breast cancer cells and highly expressed in the HER2-negative breast cancer cell line MCF7. Our results suggest that EphA2-targeted MSN for doxorubicin delivery (MSN-YSA-DOX) are more effective than MSN-DOX in treating breast cancer cell lines in vitro. CONCLUSIONS: Our preliminary observations suggest that the EphA2-targeted MSN delivery system may provide a strategy for enhancing delivery of therapeutic agents to breast cancer cells expressing EphA2, and potentially reduce toxicity while enhancing therapeutic efficacy.

Loss of fatty acid synthase suppresses the malignant phenotype of colorectal cancer cells by down-regulating energy metabolism and mTOR signaling pathway.

PURPOSE: Altered cellular metabolism has received increased attention as an important hallmark of cancer. Activation of FASN has been found to be involved in many human tumors. Despite extensive research in FASN function on cancer, the underlying mechanism is not entirely understood yet. METHODS: Cerulenin was used to suppress the FASN expression in human colorectal cancer cell lines (HT29 and LoVo). Expression of PI3K, Akt, p-Akt, mTOR, p-mTOR, FASN, and AZGP1 was measured using western blotting and qPCR. ATP and lactic acid were assessed to investigate the activation of energy metabolism. Cell cytotoxicity assay was studied by cell counting kit-8 assay. The capacity of cell proliferation and migration was investigated by clonogenic and invasion assay. Analysis of apoptosis and the cell cycle was detected by flow cytometry. RESULTS: We found that the expression of FASN was down-regulated, while the expression of PI3K, p-Akt, p-mTOR, and AZGP1 was down-regulated in HT29 and LoVo cells treated with FASN inhibitor. Proliferation was reduced in FASN inhibitor-treated cells, which is consistent with an increased apoptosis rate. Furthermore, the migration of FASN inhibitor-treated cells was decreased and the content of ATP and lactic acid was also dropped. CONCLUSION: These findings suggest that inhibited FASN suppresses the malignant phenotype of colorectal cancer cells by down-regulating energy metabolism and mTOR signaling pathway. The results have paved the way to understand the relations of FASN, mTOR signaling pathway, and energy metabolism in colorectal cancer cells.