Lymphotoxin-β 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-β (LTβ), a TNF superfamily protein that activates NF-κB, and protein arginine methyltransferase 1 (PRMT1), an arginine methyltransferase that methylates EGFR. LTβ interacts with methylated EGFR to promote its ligand-binding ability and dimerization. Furthermore, LTβ activates the NF-κB pathway through a LTβ 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-LTβ 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.

Hsu DS ，Hwang WL ，Yuh CH ，Chu CH ，Ho YH ，Chen PB ，Lin HS ，Lin HK ，Wu SP ，Lin CY ，Hsu WH ，Lan HY ，Wang HJ ，Tai SK ，Hung MC ，Yang MH ... -  《-》

A positive feedback loop involving EGFR/Akt/mTORC1 and IKK/NF-kB regulates head and neck squamous cell carcinoma proliferation.

Li Z ，Yang Z ，Passaniti A ，Lapidus RG ，Liu X ，Cullen KJ ，Dan HC ... -  《Oncotarget》

Hedgehog signaling alters reliance on EGF receptor signaling and mediates anti-EGFR therapeutic resistance in head and neck cancer.

The EGF receptor (EGFR)-directed monoclonal antibody cetuximab is the only targeted therapy approved for the treatment of squamous cell carcinoma of the head and neck (HNSCC) but is only effective in a minority of patients. Epithelial-to-mesenchymal transition (EMT) has been implicated as a drug resistance mechanism in multiple cancers, and the EGFR and Hedgehog pathways (HhP) are relevant to this process, but the interplay between the two pathways has not been defined in HNSCC. Here, we show that HNSCC cells that were naturally sensitive to EGFR inhibition over time developed increased expression of the HhP transcription factor GLI1 as they became resistant after long-term EGFR inhibitor exposure. This robustly correlated with an increase in vimentin expression. Conversely, the HhP negatively regulated an EGFR-dependent, EMT-like state in HNSCC cells, and pharmacologic or genetic inhibition of HhP signaling pushed cells further into an EGFR-dependent phenotype, increasing expression of ZEB1 and VIM. In vivo treatment with cetuximab resulted in tumor shrinkage in four of six HNSCC patient-derived xenografts; however, they eventually regrew. Cetuximab in combination with the HhP inhibitor IPI-926 eliminated tumors in two cases and significantly delayed regrowth in the other two cases. Expression of EMT genes TWIST and ZEB2 was increased in sensitive xenografts, suggesting a possible resistant mesenchymal population. In summary, we report that EGFR-dependent HNSCC cells can undergo both EGFR-dependent and -independent EMT and HhP signaling is a regulator in both processes. Cetuximab plus IPI-926 forces tumor cells into an EGFR-dependent state, delaying or completely blocking tumor recurrence.

Keysar SB ，Le PN ，Anderson RT ，Morton JJ ，Bowles DW ，Paylor JJ ，Vogler BW ，Thorburn J ，Fernandez P ，Glogowska MJ ，Takimoto SM ，Sehrt DB ，Gan GN ，Eagles-Soukup JR ，Serracino H ，Hirsch FR ，Lucia MS ，Thorburn A ，Song JI ，Wang XJ ，Jimeno A ... -  《-》

SMAD4 Loss Is Associated with Cetuximab Resistance and Induction of MAPK/JNK Activation in Head and Neck Cancer Cells.

Purpose: We previously demonstrated an association between decreased SMAD4 expression and cetuximab resistance in head and neck squamous cell carcinoma (HNSCC). The purpose of this study was to further elucidate the clinical relevance of SMAD4 loss in HNSCC.Experimental Design: SMAD4 expression was assessed by IHC in 130 newly diagnosed and 43 patients with recurrent HNSCC. Correlative statistical analysis with clinicopathologic data was also performed. OncoFinder, a bioinformatics tool, was used to analyze molecular signaling in TCGA tumors with low or high SMAD4 mRNA levels. The role of SMAD4 was investigated by shRNA knockdown and gene reconstitution of HPV-negative HNSCC cell lines in vitro and in vivoResults: Our analysis revealed that SMAD4 loss was associated with an aggressive, HPV-negative, cetuximab-resistant phenotype. We found a signature of prosurvival and antiapoptotic pathways that were commonly dysregulated in SMAD4-low cases derived from TCGA-HNSCC dataset and an independent oral cavity squamous cell carcinoma (OSCC) cohort obtained from GEO. We show that SMAD4 depletion in an HNSCC cell line induces cetuximab resistance and results in worse survival in an orthotopic mouse model in vivo We implicate JNK and MAPK activation as mediators of cetuximab resistance and provide the foundation for the concomitant EGFR and JNK/MAPK inhibition as a potential strategy for overcoming cetuximab resistance in HNSCCs with SMAD4 loss.Conclusions: Our study demonstrates that loss of SMAD4 expression is a signature characterizing the cetuximab-resistant phenotype and suggests that SMAD4 expression may be a determinant of sensitivity/resistance to EGFR/MAPK or EGFR/JNK inhibition in HPV-negative HNSCC tumors. Clin Cancer Res; 23(17); 5162-75. ©2017 AACR.

Ozawa H ，Ranaweera RS ，Izumchenko E ，Makarev E ，Zhavoronkov A ，Fertig EJ ，Howard JD ，Markovic A ，Bedi A ，Ravi R ，Perez J ，Le QT ，Kong CS ，Jordan RC ，Wang H ，Kang H ，Quon H ，Sidransky D ，Chung CH ... -  《-》

Elevated RET expression enhances EGFR activation and mediates EGFR inhibitor resistance in head and neck squamous cell carcinoma.

Co-activation of EGFR by alternative receptor tyrosine kinases (RTKs) might mediate resistance to EGFR inhibition in head and neck squamous cell carcinoma (HNSCC). Here we found a novel mechanism to improve the efficacy of EGFR inhibitor erlotinib on HNSCC. Immunohistochemistry, western blot, cell migration and invasion assays, cell proliferation, cell cycle analysis and in vivo serial transplantation assays were used to evaluate the role of RET on HNSCC cells. The elevated levels of a rearranged during transfection (RET) are observed in HNSCC and that high levels of RET correlate with increased tumor size, advanced tumor stage and decreased overall survival rate. The HNSCC cell proliferation and invasion were inhibited by RET knockdown in vitro and in vivo. The inhibition of RET expression markedly reduced EGFR phosphorylation and downstream EGFR signaling. The inhibition of RET signaling significantly increased the sensitivity of HNSCC cells to the EGFR inhibitor erlotinib in both in vitro and in vivo models. Our results offer a preclinical proof-of-concept supporting a role for RET signaling inhibition in a targeted therapeutic approach to improve the efficacy of EGFR inhibition in HNSCC.

Lin C ，Lu W ，Ren Z ，Tang Y ，Zhang C ，Yang R ，Chen Y ，Cao W ，Wang L ，Wang X ，Ji T ... -  《-》