EGFR and STAT3 are good targets for cancers treatment. Thus, agents such as the anti-EGFR antibody cetuximab, the EGFR tyrosine kinase inhibitor gefitinib, and STAT3 inhibitors (such
as S3I-201 or JSI-124) could be used in preclinical models or each phase of clinical trials [69–71]. Interestingly, a novel STAT3 inhibitor S3I-1747 selectively interrupt the interaction of EGFR and STAT3 directly . Those reports also suggested that either an anti-EGFR or anti-STAT3 agent might be a potent chemopreventive agent for patients with anti-invasion and anoikis-sensitizing activities. Therapies such as monoclonal antibodies and tyrosine kinase inhibitors targeting EGFR have demonstrated limited anti-tumor efficacy [71, 73]; however, reports of combined targeting
of EGFR and STAT3 are few. Recently, EBV LMP1-specific DNAzyme, DZ1, inhibits the majority of oncogenic signaling pathways converging Selleckchem ATM Kinase Inhibitor on sets of transcription selleck screening library factors that ultimately control gene expression patterns resulting in tumor formation, progression, and metastasis.  Our data showed that DZ1 can inhibit EBV LMP1-induced promoter activity of cyclin D1 via EGFR or STAT3 and that DZ1 enhanced cyclin D1 promoter inhibition based on experiments with mutants of EGFR or STAT3. These results suggest that combining inhibitors for EGFR/STAT3 and DZ1 in LMP-expressing cancers may be a promising therapeutic strategy. The combination of Src and EGFR inhibition with Gemcitabine selleck products treatment in STAT3-mediated therapy-resistant pancreatic tumors was also effective at inhibiting the growth of xenografts of both therapy-sensitive and -resistant pancreatic cancer cells in vivo
without increasing toxicity . It is possible that EGFR and STAT3, individually or as a pair, contribute to tumor progression. Alternatively, crosstalk Inositol monophosphatase 1 between signaling pathways provides a potential route to overcome the blockade of a single or double targeted therapies, but this can be overcome by the blockade of multiple targets. Our data provide further evidence that the combination of three inhibitors may be efficacious for cancer, and more extensive investigation will be required. In summary, we found that EBV LMP1 enhances the transcriptional activity and mRNA level of the cyclin D1 gene in CNE1 cells. This underlying mechanism for cyclin D1 regulation involves regulated binding of EGFR and STAT3 in the cyclin D1 promoter region as well as increasing the promoter activity of the cyclin D1 gene. Such a mechanism may partially contribute to the proliferation and growth of tumor cells with an LMP1-induced increase in the nuclear accumulation of EGFR and STAT3. Acknowledgements We would like to thanks members of the lab for critical discussions of this manuscript.