Reversal of increased mammary tumorigenesis by valproic acid and hydralazine in offspring of dams fed high fat diet during pregnancy

F De Oliveira Andrade,L Hilakivi-Clarke,A Warri,N M Nguyen

doi:10.1038/s41598-019-56854-5

Abstract

Maternal or paternal high fat (HF) diet can modify the epigenome in germ cells and fetal somatic cells leading to an increased susceptibility among female offspring of multiple generations to develop breast cancer. We determined if combined treatment with broad spectrum DNA methyltransferase (DNMT) inhibitor hydralazine and histone deacetylase (HDAC) inhibitor valproic acid (VPA) will reverse this increased risk. C57BL/6 mouse dams were fed either a corn oil-based HF or control diet during pregnancy. Starting at age 7 weeks, female offspring were administered 3 doses of 7,12-dimethylbenz[a]anthracene (DMBA) to initiate mammary cancer. After last dose, offspring started receiving VPA/hydralazine administered via drinking water: no adverse health effects were detected. VPA/hydralazine reduced mammary tumor multiplicity and lengthened tumor latency in HF offspring when compared with non-treated HF offspring. The drug combination inhibited DNMT3a protein levels and increased expression of the tumor suppressor gene Cdkn2a/p16 in mammary tumors of HF offspring. In control mice not exposed to HF diet in utero, VPA/hydralazine increased mammary tumor incidence and burden, and elevated expression of the unfolded protein response and autophagy genes, including HIF-1α, NFkB, PERK, and SQSTM1/p62. Expression of these genes was already upregulated in HF offspring prior to VPA/hydralazine treatment. These findings suggest that breast cancer prevention strategies with HDAC/DNMT inhibitors need to be individually tailored.

Highlights

Maternal or paternal high fat (HF) diet can modify the epigenome in germ cells and fetal somatic cells leading to an increased susceptibility among female offspring of multiple generations to develop breast cancer
Since HF and control diets fed to pregnant dams are isocaloric, no differences in body weights occurred between the non-treated control and HF offspring at any stage of their life-cycle[14]
An increase in mammary cancer risk following an in utero exposure to a HF diet or to endocrine disrupting chemicals is associated with epigenetic changes

Summary

Introduction

Maternal or paternal high fat (HF) diet can modify the epigenome in germ cells and fetal somatic cells leading to an increased susceptibility among female offspring of multiple generations to develop breast cancer. In control mice not exposed to HF diet in utero, VPA/hydralazine increased mammary tumor incidence and burden, and elevated expression of the unfolded protein response and autophagy genes, including HIF-1α, NFkB, PERK, and SQSTM1/p62. Expression of these genes was already upregulated in HF offspring prior to VPA/hydralazine treatment These findings suggest that breast cancer prevention strategies with HDAC/DNMT inhibitors need to be individually tailored. We12–14 and others[15,16,17,18] have found an increase in mammary cancer risk following an in utero exposure to a high fat (HF) diet in preclinical animal models These maternal exposures may affect key reproductive factors, such as induce an early puberty onset[12,19], which are linked to an increased breast cancer risk[20]. Our findings suggest that similar to the idea that patients with different gene expression signatures in their breast cancers need an individualized treatment plan[40], approaches to prevent breast cancer should be tailored to reflect a woman’s breast cancer susceptibility factors

Objectives

Methods

Results

Conclusion