Abstract P4-04-08: Histological and epigenetic analyses of placenta tissue from breast cancer patients and healthy participants

Background: Breast cancer is one of the most common malignancies during pregnancy. Guidelines for breast cancer treatment during pregnancy demonstrating that breast cancer during pregnancy can be treated similarly to non-pregnancy-associated breast cancer, except for hormonal and anti-HER2 therapies. Nonetheless, a decreased birth weight is often observed in newborns. Therefore, this project aims to analyze the effects of chemotherapy and the impact of cancer progression on the placenta. Methods: Placentas from breast cancer patients (n=63) and non-cancer participants (n=20) enrolled in Breast Cancer in Pregnancy (BCP) study were collected after delivery and embedded in paraffin. Sections were stained with Hematoxylin-Eosin (HE) and IHC (Ki-67, cPARP, p27Kip1); trophoblast morphology was evaluated by an established scoring system and distribution of immunohistochemical markers was assessed. Additionally, epigenetic analyses (cytosine methylation) for the following genes were performed: LINE-1 (general methylation), IGF2-H19 (birth weight), EPO (hypoxia), BDNF (neurobiological development), glucocorticoid receptor, HSD11B2 (inactivation of glucocorticoids), estrogen receptor, P-glycoprotein, CYP-3A4 (drug metabolism). Results: HE staining revealed significant damage of trophoblast nuclei and membranes in placentas from breast cancer patients compared to controls (mean score of damage 1.9/1.8 vs 0.8/0.7, p<0.001). Simultaneously, mean proliferation index (Ki-67 positive cells/ 1000 trophoblasts) was reduced (36.3 vs 58.0, p<0.001). In contrast, nuclear and cytoplasmic expression of the negative cell cycle regulator p27Kip1 was reduced (mean IRS score 1.0/0.9 vs 4.3/4.8, p<0.001). No evidence of enhanced apoptosis was found. Epigenetic analyses showed significant differences in mean percentage of cytosine methylation of EPO (68.4% vs 71.1%, p<0.05) and hCyp-3A4 (87.8% vs 90.0%, p<0.01) gene. Altered methylation of CpG positions of LINE-1, IGF2-H19, HSD11B2, estrogen receptor and P-glycoprotein gene were found. Conclusions: Placentas from breast cancer patients seem to be harmed in contrast to placentas from normal pregnancies, shown by morphologic abnormalities and a decreased proliferation index. Nevertheless, no increase of apoptotic cells could be demonstrated. Altered expression of efflux pumps or drug-metabolizing enzymes might be a reason for good fetal tolerability of chemotherapy during pregnancy as methylation patterns were changed in P-glycoprotein and CYP-3A4 gene.

Citation Format: Karolin Fröhlich, Torsten Plösch, Fenja Seither, Volkmar Müller, Thomas Karn, Elmar Stickeler, Christian Schem, Christine Solbach, Amelie Lupp, Rikst N Verkaik-Schakel, Gitta Turowski, Peter Mallmann, Marion van Mackelenbergh, Bruno Sinn, Valentina Nekljudova, Carsten Denkert, Pamela Schittler, Udo Markert, Sibylle Loibl. Histological and epigenetic analyses of placenta tissue from breast cancer patients and healthy participants [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-04-08.

Parental vitamin D deficiency during pregnancy is associated with increased blood pressure in offspring via Panx1 hypermethylation

Vitamin D deficiency is one of the most common nutritional deficiencies worldwide. Maternal vitamin D deficiency is associated with increased susceptibility to hypertension in offspring, but the reasons for this remain unknown. The aim of this study was to determine if parental vitamin D deficiency leads to altered DNA methylation in offspring that may relate to hypertension. Male and female Sprague-Dawley rats were fed a standard or vitamin D-depleted diet. After 10 wk, nonsibling rats were mated. The conceived pups received standard chow. We observed an increased systolic and diastolic blood pressure in the offspring from depleted parents (F1-depl). Genome-wide methylation analyses in offspring identified hypermethylation of the promoter region of the Pannexin-1 (Panx1) gene in F1-depl rats. Panx1 encodes a hemichannel known to be involved in endothelial-dependent relaxation, and we demonstrated that in F1-depl rats the increase in blood pressure was associated with impaired endothelial relaxation of the large vessels, suggesting an underlying biological mechanism of increased blood pressure in children from parents with vitamin deficiency. Parental vitamin D deficiency is associated with epigenetic changes and increased blood pressure levels in offspring.