Induction of DNMT3B by PGE2 and IL6 at Distant Metastatic Sites Promotes Epigenetic Modification and Breast Cancer Colonization

Abstract

Current cancer treatments are largely based on the genetic characterization of primary tumors and are ineffective for metastatic disease. Here we report that DNA methyltransferase 3B (DNMT3B) is induced at distant metastatic sites and mediates epigenetic reprogramming of metastatic tumor cells. Multi-omics analysis and spontaneous metastatic mouse models revealed that DNMT3B alters multiple pathways including STAT3, NFκB, PI3K/Akt, β-catenin, and Notch signaling, which are critical for cancer cell survival, apoptosis, proliferation, invasion, and colonization. PGE2 and IL-6 were identified as critical inflammatory mediators in DNMT3B induction. DNMT3B expression levels positively correlated with human metastatic progression. Targeting IL-6 or COX-2 reduced DNMT3B induction and improved chemo- or PD1- therapy. We propose a novel mechanism linking the metastatic microenvironment with epigenetic alterations that occur at distant sites. These results caution against the "Achilles' heel" in cancer therapies based on primary tumor characterization and suggests targeting DNMT3B induction as new option for treating metastatic disease.