Gene expression profiles for low-dose exposure to diethyl phthalate in rodents and humans: a translational study with implications for breast carcinogenesis

Kalpana Gopalakrishnan,Humberto Parada,Simona Panzacchi,Susan L Teitelbaum,Fiorella Belpoggi,Vasily N Aushev,Hanina Hibshoosh,Fabiana Manservisi,Jia Chen,Laura Falcioni,Regina M Santella,Marilie D Gammon,Gail Garbowski

doi:10.1038/s41598-020-63904-w

Abstract

Phthalates are commonly included as ingredients in personal care products such as cosmetics, shampoos and perfumes. Diethyl phthalate (DEP) has been found to be anti-androgenic and linked with adverse reproductive effects on males, but effects on females are poorly understood. We designed an integrative and translational study to experimentally examine the effects of DEP exposure at a human-equivalent dose on the mammary transcriptome in rats and to subsequently examine the DEP gene signature in breast tissues (both pre-malignant and tumor) from a population study. In Sprague-Dawley rats treated orally with DEP from birth to adulthood, we identified a signature panel of 107 genes predominantly down-regulated by DEP exposure. Univariate analysis of this 107 DEP gene signature in pre-malignant breast tissues revealed that six genes (P4HA1, MPZL3, TMC4, PLEKHA6, CA8, AREG) were inversely associated with monoethyl phthalate (MEP; the urinary metabolite of DEP) concentration (p < 0.05) among postmenopausal women; all six genes loaded on to one of seven factors identified by factor analysis. Transcription factor enrichment analysis revealed that genes in this factor were enriched for androgen receptor binding sites. These six genes were also significantly down-regulated in pre-malignant adjacent tissues compared to the corresponding tumor tissues in pair-wise analyses (p < 0.05). Results from our translational study indicate that low level exposure to diethyl phthalate results in measurable genomic changes in breast tissue with implications in breast carcinogenesis.

Highlights

Phthalates are commonly included as ingredients in personal care products such as cosmetics, shampoos and perfumes
We recently reported results from the Long Island Breast Cancer Study Project (LIBCSP) in which we did not observe any significant associations between urinary level of monoethyl phthalate (MEP) and breast cancer risk, while inverse associations were observed for mono(3-carboxypropyl) phthalate (MCPP) and monocarboxyoctyl phthalate (MCOP), metabolites of anti-androgenic phthalates[13]
We identified the human orthologs of the rat genes resulting in 91 orthologous human genes in the parous group (‘Diethyl phthalate (DEP) parous gene signature’) and 34 orthologous human genes in the nulliparous group (‘DEP nulliparous gene signature’) (Supplementary Table 1)

Summary

Introduction

Phthalates are commonly included as ingredients in personal care products such as cosmetics, shampoos and perfumes. In SpragueDawley rats treated orally with DEP from birth to adulthood, we identified a signature panel of 107 genes predominantly down-regulated by DEP exposure Univariate analysis of this 107 DEP gene signature in pre-malignant breast tissues revealed that six genes (P4HA1, MPZL3, TMC4, PLEKHA6, CA8, AREG) were inversely associated with monoethyl phthalate (MEP; the urinary metabolite of DEP) concentration (p < 0.05) among postmenopausal women; all six genes loaded on to one of seven factors identified by factor analysis. We identified a DEP gene signature in normal developing mammary glands in SD rats, and subsequently examined this signature in pre-malignant and breast cancer tissues from a subsample of women who participated in a population-based study. The overall goal of the study is to examine whether human level exposure to DEP induces measurable transcriptomic changes in target tissues, shedding light on the possible causal relationship between phthalate exposure and breast cancer

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Conclusion