Identification of Novel Anti-Liver Cancer Small Molecules with Better Therapeutic Index than Sorafenib via Zebrafish Drug Screening Platform.

Hepatocellular carcinoma (HCC) ranks as the fourth leading cause of cancer-related deaths worldwide. Sorafenib was the only U.S. Food and Drug Administration (FDA) approved drug for treating advanced HCC until recently, so development of new target therapy is urgently needed. In this study, we established a zebrafish drug screening platform and compared the therapeutic effects of two multiple tyrosine kinase inhibitors, 419S1 and 420S1, with Sorafenib. All three compounds exhibited anti-angiogenesis abilities in immersed fli1:EGFP transgenic embryos and the half inhibition concentration (IC50) was determined. 419S1 exhibited lower hepatoxicity and embryonic toxicity than 420S1 and Sorafenib, and the half lethal concentration (LC50) was determined. The therapeutic index (LC50/IC50) for 419S1 was much higher than for Sorafenib and 420S1. The compounds were either injected retro-orbitally or by oral gavage to adult transgenic zebrafish with HCC. The compounds not only rescued the pathological feature, but also reversed the expression levels of cell-cycle-related genes and protein levels of a proliferation marker. Using a patient-derived-xenograft assay, we found that the effectiveness of 419S1 and 420S1 in preventing liver cancer proliferation is better than that of Sorafenib. With integrated efforts and the advantage of the zebrafish platform, we can find more effective and safe drugs for HCC treatment and screen for personalized medicine.

Lymphotoxin-ß Interacts with Methylated EGFR to Mediate Acquired Resistance to Cetuximab in Head and Neck Cancer.

Purpose: In head and neck squamous cell carcinoma (HNSCC), the incidence of RAS mutation, which is the major cause of cetuximab resistance, is relatively rare compared with the other types of cancers, and the mechanism mediating acquired resistance is unclear compared with the driver gene mutation-mediated de novo resistance. Here, we investigated the driver gene mutation-independent mechanism for cetuximab resistance in HNSCC.Experimental Design: We used the in vitro-selected and in vivo-selected cetuximab-resistant sublines of HNSCC cell lines for investigating the mechanism of acquired resistance to cetuximab. Zebrafish model was applied for evaluating the synergistic effect of combinatory drugs for overcoming cetuximab resistance.Results: The cetuximab-resistant HNSCC cells undergo a Snail-induced epithelial-mesenchymal transition. Mechanistically, Snail induces the expression of lymphotoxin-ß (LTß), a TNF superfamily protein that activates NF-κB, and protein arginine methyltransferase 1 (PRMT1), an arginine methyltransferase that methylates EGFR. LTß interacts with methylated EGFR to promote its ligand-binding ability and dimerization. Furthermore, LTß activates the NF-κB pathway through a LTß receptor-independent mechanism. Combination of an EGFR tyrosine kinase inhibitor and a NF-κB inhibitor effectively suppressed cetuximab-resistant HNSCC and interfering with the EGFR-LTß interaction reverses resistance.Conclusions: Our findings elucidate the mechanism of driver gene mutations-independent mechanism of acquired resistance to cetuximab in HNSCC and also provide potential strategies for combating cetuximab resistance. Clin Cancer Res; 23(15); 4388-401. ©2017 AACR.