Targeting tumor heterogeneity and breast cancer metastasis through the metastatic microenvironment mediated epigenetic reprogramming

Abstract Targeting tumor heterogeneity and breast cancer metastasis through the metastaticmicroenvironment mediated epigenetic reprogrammingLi Yang and Jae Young So, Nicolas Skrypek, Anand Merchant, George Nelson, Howard H.Yang, Maxwell P. LeeNational Cancer Institute, National Institutes of Health, Bethesda, MD 20892Current cancer treatments are largely based on the genetic characterization of primarytumors and are ineffective for metastatic disease. There is lack of mechanistic understanding ashow cancer cells are selected and evolved to establish distant metastatic colonies. In addition,tumor heterogeneity and biomarker identification remain to be some of the most difficultchallenges in cancer treatment. In the current study, we discovered an increased DNAmethyltransferase 3B (DNMT3B) in metastatic nodules and in tumor cells with epithelia tomesenchymal (EMT) phenotype. Of great interest, high levels of DNMT3B were correlated withpoor clinical outcomes in multiple human breast cancer datasets. Mechanistically, DNMT3Balters multiple pathways including STAT3, NFkappaB, PI3K/Akt, beta-catenin, Notch signalingas well as EMT, which are critical for cancer cell survival, apoptosis, proliferation, invasion, andcolonization. We further identified PGE2 and IL6 as critical inflammatory mediators inDNMT3B induction. Importantly, targeting IL6 or PGE2 production reduced DNMT3Bexpression and improved chemo treatment or PD1 immune therapy. Furthermore, perioperative(surgical removal of primary tumors) targeting DNMT3B in combination with chemotherapymarkedly suppressed tumor recurrence and metastasis in preclinical mouse models for triplenegative breast cancer. Our studies identify DNMT3B as an important mechanism fortranscription regulation in tumor heterogeneity that is critical for tumor invasion and metastasis,thus suggesting a validated target for treating metastatic disease. Citation Format: Li Yang, Jae Young So, Nicolas Skrypek, Anand Merchant, George Nelson, Howard Yang, Maxwell Lee. Targeting tumor heterogeneity and breast cancer metastasis through the metastatic microenvironment mediated epigenetic reprogramming [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-05-08.