The combination of NVP-BEZ235 and rapamycin regulates nasopharyngeal carcinoma cell viability and apoptosis via the PI3K/AKT/mTOR pathway

Identification of galactosamine-(N-acetyl)-6-sulfatase (GALNS) as a novel therapeutic target in progression of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a commonly diagnosed malignancy in southern China and southeast Asia. Previous studies have identified galactosamine-(N-acetyl)-6-sulfatase (GALNS) as a potential biomarker for multiple cancers. However, it is unknown whether GALNS plays a role in NPC development, and the underlying mechanisms remain unclear. In this study, we found that GALNS is overexpressed in NPC cell lines and tissues compared to the normal nasopharyngeal counterparts. Knocking down GALNS expression in the NPC cells significantly decreased their proliferation in vitro, and inhibited xenograft growth in a mouse model. Mechanistically, the anti-proliferative effect of GALNS silencing was the result of autophagy induction via the inhibition of PI3K-AKT-mTOR signaling pathway. Taken together, GALNS drives the progression of NPC via PI3K-AKT-mTOR signaling-mediated autophagy, and is therefore a promising therapeutic target.

TOM40 regulates the progression of nasopharyngeal carcinoma through ROS-mediated AKT/mTOR and p53 signaling

Nasopharyngeal carcinoma (NPC) is a prevalent cancer in Southern China, North Africa, and Southeast Asia. The translocase of the outer membrane (TOM) 40 is a transporter of mitochondrial proteins, and is involved in ovarian cancer cell growth. However, its role in the progression of NPC is still unclear. We found that TOM40 levels were upregulated in NPC tissues and multiple NPC cell lines. In addition, high TOM40 expression in the tumor tissues was associated with poor overall survival and disease specific survival. TOM40 knockdown in the NPC cell lines inhibited their proliferation in vitro and in vivo. Furthermore, TOM40 silencing also increased intracellular production of reactive oxygen species (ROS) and decreased mitochondrial membrane potential (MMP). Mechanistically, the anti-tumor effects of TOM40 silencing were dependent on the inhibition of AKT/mTOR signaling and activation of p53 signaling. To summarize, TOM40 mediates NPC progression through ROS-mediated AKT/mTOR and p53 signaling. Our findings highlight the potential of TOM40 as a therapeutic target for NPC.

Insight into the roles of tyrosine on rCHO cell performance in fed-batch cultures

Tyrosine (Tyr), as one of the least soluble amino acids, is essential to monoclonal antibody (mAb) production in recombinant Chinese hamster ovary (rCHO) cell cultures since its roles on maintaining the specific productivity (q_mAb) and avoiding Tyr sequence variants. To understand the effects of Tyr on cell performance and its underlying mechanisms, rCHO cell-producing mAbs were cultivated at various cumulative Tyr addition concentrations (0.6 to 5.5 mM) in fed-batch processes. Low Tyr concentrations gave a much lower peak viable cell density (VCD) during the growth phase and also induced rapid cell death and pH decrease during the production phase, resulting in a low efficient fed-batch process. Autophagy was initiated following the inhibition of mTOR under the Tyr starvation condition. Excessive autophagy subsequently induced autophagic cell death, which was found as the major type of cell death in this study. Additionally, the results obtained here demonstrate that the decrease in culture pH under the Tyr starvation condition was associated with the autophagy and such pH drop might be attributed to the lysosome acidification and cell lysis.