Effect of preeclampsia on umbilical cord blood stem cells in relation to breast cancer susceptibility in the offspring

Constitutional BRCA1 Methylation and Risk of Incident Triple-Negative Breast Cancer and High-grade Serous Ovarian Cancer

Importance

About 25% of all triple-negative breast cancers (TNBCs) and 10% to 20% of high-grade serous ovarian cancers (HGSOCs) harbor BRCA1 promoter methylation. While constitutional BRCA1 promoter methylation has been observed in normal tissues of some individuals, the potential role of normal tissue methylation as a risk factor for incident TNBC or HGSOC is unknown.

Objective

To assess the potential association between white blood cell BRCA1 promoter methylation and subsequent risk of incident TNBC and HGSOC.

Design, Setting, and Participants

This case-control study included women who were participating in the Women's Health Initiative study who had not received a diagnosis of either breast or ovarian cancer before study entrance. A total of 637 women developing incident TNBC and 511 women developing incident HGSOC were matched with cancer-free controls (1841 and 2982, respectively) in a nested case-control design. Cancers were confirmed after central medical record review. Blood samples, which were collected at entry, were analyzed for BRCA1 promoter methylation by massive parallel sequencing. The study was performed in the Mohn Cancer Research Laboratory (Bergen, Norway) between 2019 and 2022.

Main Outcomes and Measures

Associations between BRCA1 methylation and incident TNBC and incident HGSOC were analyzed by Cox proportional hazards regression.

Results

Of 2478 cases and controls in the TNBC group and 3493 cases and controls in the HGSOC group, respectively, 7 (0.3%) and 3 (0.1%) were American Indian or Alaska Native, 46 (1.9%) and 30 (0.9%) were Asian, 1 (0.04%) and 1 (0.03%) was Native Hawaiian or Pacific Islander, 326 (13.2%) and 125 (3.6%) were Black or African, 56 (2.3%) and 116 (3.3%) were Hispanic, 2046 (82.6%) and 3257 (93.2%) were White, and 35 (1.4%) and 35 (1.0%) were multiracial. Median (range) age at entry was 62 (50-79) years, with a median interval to diagnosis of 9 (TNBC) and 10 (HGSOC) years. Methylated BRCA1 alleles were present in 194 controls (5.5%). Methylation was associated with risk of incident TNBC (12.4% methylated; HR, 2.35; 95% CI, 1.70-3.23; P < .001) and incident HGSOC (9.4% methylated; HR, 1.93; 95% CI, 1.36-2.73; P < .001). Restricting analyses to individuals with more than 5 years between sampling and cancer diagnosis yielded similar results (TNBC: HR, 2.52; 95% CI, 1.75-3.63; P < .001; HGSOC: HR, 1.82; 95% CI, 1.22-2.72; P = .003). Across individuals, methylation was not haplotype-specific, arguing against an underlying cis-acting factor. Within individuals, BRCA1 methylation was observed on the same allele, indicating clonal expansion from a single methylation event. There was no association found between BRCA1 methylation and germline pathogenic variant status.

Conclusions and Relevance

The results of this case-control suggest that constitutional normal tissue BRCA1 promoter methylation is significantly associated with risk of incident TNBC and HGSOC, with potential implications for prediction of these cancers. These findings warrant further research to determine if constitutional methylation of tumor suppressor genes are pancancer risk factors.

Risks of cause-specific mortality in offspring of pregnancies complicated by hypertensive disease of pregnancy

BACKGROUND

Fetal environment has a substantial influence on an individual's health throughout their life course. Animal models of hypertensive disease of pregnancy have demonstrated adverse health outcomes among offspring exposed to hypertensive disease of pregnancy in utero. Although there are numerous descriptions of the neonatal, infant, and pediatric outcomes of human offspring affected by hypertensive disease of pregnancy, there are few data in US populations on later life outcomes, including mortality.

OBJECTIVE

To assess risk for early mortality among offspring of pregnancies complicated by hypertensive disease of pregnancy.

STUDY DESIGN

This is a retrospective cohort study of offspring born to women with singleton or twin pregnancies between 1947 and 1967 with birth certificate information in the Utah Population Database. We identified offspring from delivery diagnoses of gestational hypertension, preeclampsia, or eclampsia. Offspring from these pregnancies (exposed) were matched to offspring of pregnancies without hypertensive disease of pregnancy (unexposed) by maternal age at delivery, birth year, sex, and multiple gestation. We also identified unexposed siblings of exposed offspring for a separate sibling analysis. Mortality follow-up of all offspring continued through 2016, at which time they would have been 49-69 years old. Adjusted hazard ratios for cause-specific mortality comparing exposed with unexposed offspring were estimated using Cox proportional hazard models.

RESULTS

We compared mortality risks for 4050 exposed offspring and 6989 matched unexposed offspring from the general population and 7496 unexposed siblings. Mortality risks due to metabolic, respiratory, digestive, nervous, and external causes of death did not differ between exposed and unexposed groups. Mortality risks from cardiovascular disease were greater in exposed offspring compared with unexposed offspring (adjusted hazard ratio, 1.57; 95% confidence interval, 1.16-2.12). In sex-specific models among the general population, cardiovascular disease mortality was significantly associated with exposure among male patients (adjusted hazard ratio, 1.92; 95% confidence interval, 1.27-2.88) but not among female patients (adjusted hazard ratio, 0.97; 95% confidence interval, 0.81-1.94). An interaction between hypertensive disease of pregnancy exposure and birth order on cardiovascular disease mortality was significant (P=.047), suggesting that the effect of hypertensive disease of pregnancy on cardiovascular disease mortality increased with higher birth order. Among siblings, the association between hypertensive disease of pregnancy exposure and cardiovascular disease mortality was not significant (adjusted hazard ratio, 1.39; 95% confidence interval, 0.99-1.95), and this was also true for sex-specific analyses of males (adjusted hazard ratio, 1.26; 95% confidence interval, 0.81-1.94) and females (adjusted hazard ratio, 1.71; 95% confidence interval, 0.96-3.04). As in the general population, there was a significant interaction between hypertensive disease of pregnancy exposure and birth order on cardiovascular disease mortality (P=.011).

CONCLUSION

In a US population, overall mortality risks are greater for offspring of pregnancies complicated by hypertensive disease of pregnancy compared with unexposed offspring. Among siblings, there was not a significant association between hypertensive disease of pregnancy exposure and cardiovascular disease mortality.

Constitutional Mosaic Epimutations - a hidden cause of cancer?

Silencing of tumor suppressor genes by promoter hypermethylation is a key mechanism to facilitate cancer progression in many malignancies. While promoter hypermethylation can occur at later stages of the carcinogenesis process, constitutional methylation of key tumor suppressors may be an initiating event whereby cancer is started. Constitutional BRCA1 methylation due to cis-acting germline genetic variants is associated with a high risk of breast and ovarian cancer. However, this seems to be a rare event, restricted to a very limited number of families. In contrast, mosaic constitutional BRCA1 methylation is detected in 4-7% of newborn females without germline BRCA1 mutations. While the cause of such methylation is poorly understood, mosaic normal tissue BRCA1 methylation is associated with a 2-3 fold increased risk of high-grade serous ovarian cancer (HGSOC). As such, BRCA1 methylation may be the cause of a significant number of ovarian cancers. Given the molecular similarities between HGSOC and basal-like breast cancer, the findings with respect to HGSOC suggest that constitutional BRCA1 methylation could be a risk factor for basal-like breast cancer as well. Similar to BRCA1, some specific germline variants in MLH1 and MSH2 are associated with promoter methylation and a high risk of colorectal cancers in rare hereditary cases of the disease. However, as many as 15% of all colorectal cancers are of the microsatellite instability (MSI) "high" subtype, in which commonly the tumors harbor MLH1 hypermethylation. Constitutional mosaic methylation of MLH1 in normal tissues has been detected but not formally evaluated as a potential risk factor for incidental colorectal cancers. However, the findings with respect to BRCA1 in breast and ovarian cancer raises the question whether mosaic MLH1 methylation is a risk factor for MSI positive colorectal cancer as well. As for MGMT, a promoter variant is associated with elevated methylation across a panel of solid cancers, and MGMT promoter methylation may contribute to an elevated cancer risk in several of these malignancies. We hypothesize that constitutional mosaic promoter methylation of crucial tumor suppressors may trigger certain types of cancer, similar to germline mutations inactivating the same particular genes. Such constitutional methylation events may be a spark to ignite cancer development, and if associated with a significant cancer risk, screening for such epigenetic alterations could be part of cancer prevention programs to reduce cancer mortality in the future.

Variations in Umbilical Cord Hematopoietic and Mesenchymal Stem Cells With Bronchopulmonary Dysplasia

Objective: To test the hypothesis that umbilical cord blood-derived CD34+ hematopoietic stem cells (HPSC), cord tissue-derived CD90+ and CD105+ mesenchymal stem cells (MSC) vary with bronchopulmonary dysplasia (BPD). Methods: We conducted a prospective longitudinal study at a large birth center (Prentice Women's Hospital in Chicago, IL). Premature infants (N = 200) were enrolled in 2:1:1 ratio based on gestational age (GA): mildly preterm (31-32 weeks), moderately preterm (29-30 weeks), and extremely preterm (23-28 weeks). Cord blood (CB) and cord tissues (CT) were collected at birth using commercial banking kits, and analyzed for collection blood volume, tissue mass, CD34+, CD90+, CD105+ counts, and concentrations. Multiplex immunoassay was used to measure 12 cytokines and growth factors in CB plasma of 74 patients. BPD severity was defined according to NIH consensus definitions. Univariate and multivariate regression models were used to identify perinatal covariates and assess associations between stem cell concentrations, cytokines, and BPD outcomes. Results: Of 200 patients enrolled (mean GA = 30 ± 2 weeks), 30 developed mild, 24 moderate, and 19 severe BPD. Concentrations of HPSC and MSC, as measured by %CD34+, %CD90+, and %CD105+ of total cells, increased with degree of prematurity. Collection parameters varied with GA, birth weight (BW), gender, prolonged rupture of membranes, mode of delivery, chorioamnionitis, and multiple gestation. Moderate-severe BPD or death was increased with lower GA, BW, Apgar scores, and documented delayed cord clamping. %CD34+ and %CD90+ were increased with BPD and directly correlated with BPD severity. Severe BPD was positively associated with %CD34+ (beta-coefficient = 0.9; 95% CI = 0.4-1.5; P < 0.01) and %CD90+ (beta-coefficient = 0.4; 95% CI = 0.2-0.6; P < 0.001) after adjustment for covariates. CB plasma granulocyte-colony stimulating factor (G-CSF) was inversely associated with %CD90+, and decreased with BPD. Below median G-CSF combined with elevated %CD90+ predicted BPD (positive predictive value = 100%). Conclusions: CB and CT collections yielded high concentrations of HPSCs and MSCs in BPD infants, accompanied by low circulating G-CSF. These variations suggest possible mechanisms by which stem cell differentiation and function predict BPD.

Prenatal Maternal Physical Activity and Stem Cells in Umbilical Cord Blood

PURPOSE

Early life processes, through influence on fetal stem cells, affect postnatal and adult health outcomes. This study examines the effects of physical activity before and during pregnancy on stem cell counts in umbilical cord blood.

METHODS

We isolated mononuclear cells from umbilical cord blood samples from 373 singleton full-term pregnancies and quantified hematopoietic (CD34(+), CD34(+)CD38(-), and CD34(+) c-kit(+)), endothelial (CD34(+)CD133(+), CD34(+)CD133(+)VEGFR2(+), CD34(+)VEGFR2(+), and CD133(+)VEGFR2(+)), and putative breast (EpCAM(+), EpCAM(+)CD49f(+), EpCAM(+)CD49f(+)CD117(+), CD49f(+)CD24(+), CD24(+)CD29(+), and CD24(+)CD29(+)CD49f(+)) stem/progenitor cell subpopulations by flow cytometry. Information on physical activities before and during pregnancy was obtained from questionnaires. Weekly energy expenditure was estimated based on metabolic equivalent task values.

RESULTS

Prepregnancy vigorous exercise was associated positively with levels of endothelial CD34(+)CD133(+), CD34(+)CD133(+)VEGFR2(+), CD34(+)VEGFR2(+), and CD133(+)VEGFR2(+ )progenitor cell populations (P = 0.02, P = 0.01, P = 0.001, and P = 0.003, respectively); positive associations were observed in samples from the first births and those from the second or later births. Prepregnancy moderate and light exercises and light exercise during the first trimester were not significantly associated with any stem/progenitor cell population. Light exercise during the second trimester was positively associated with CD34(+)VEGFR2(+) endothelial progenitor cells (P = 0.03). In addition, levels of EpCAM(+)CD49f(+) and CD49f(+)CD24(+) breast stem cells were significantly lower among pregnant women who engaged in vigorous/moderate exercise during pregnancy (P = 0.05 and P = 0.02, respectively).

CONCLUSIONS

Vigorous exercise before pregnancy increases the number of endothelial progenitor cells in umbilical cord blood and thus could potentially enhance endothelial function and improve cardiovascular fitness in the offspring. Findings of lower levels of putative breast stem cell subpopulations could have implications on exercise and breast cancer prevention. Prenatal effects of exercise on fetal stem cells warrant further studies.

Child Poverty and the Promise of Human Capacity: Childhood as a Foundation for Healthy Aging

The effect of child poverty and related early life experiences on adult health outcomes and patterns of aging has become a central focus of child health research and advocacy. In this article a critical review of this proliferating literature and its relevance to child health programs and policy are presented. This literature review focused on evidence of the influence of child poverty on the major contributors to adult morbidity and mortality in the United States, the mechanisms by which these associations operate, and the implications for reforming child health programs and policies. Strong and varied evidence base documents the effect of child poverty and related early life experiences and exposures on the major threats to adult health and healthy aging. Studies using a variety of methodologies, including longitudinal and cross-sectional strategies, have reported significant findings regarding cardiovascular disorders, obesity and diabetes, certain cancers, mental health conditions, osteoporosis and fractures, and possibly dementia. These relationships can operate through alterations in fetal and infant development, stress reactivity and inflammation, the development of adverse health behaviors, the conveyance of child chronic illness into adulthood, and inadequate access to effective interventions in childhood. Although the reviewed studies document meaningful relationships between child poverty and adult outcomes, they also reveal that poverty, experiences, and behaviors in adulthood make important contributions to adult health and aging. There is strong evidence that poverty in childhood contributes significantly to adult health. Changes in the content, financing, and advocacy of current child health programs will be required to address the childhood influences on adult health and disease. Policy reforms that reduce child poverty and mitigate its developmental effects must be integrated into broader initiatives and advocacy that also attend to the health and well-being of adults.