Association of Fetal Hormone Levels with Stem Cell Potential: Evidence for Early Life Roots of Human Cancer

Association between birth weight and risk of nonneurological childhood cancers: a systematic review and meta-analysis

OBJECTIVES

This systematic review aims to synthesize the available literature to determine the association between birthweight and the risk of nonneurological childhood cancers.

METHODS

We conducted a systematic search of PubMed, Web of Science, and Scopus databases up to May 2023 to identify observational studies. Heterogeneity between studies was evaluated using the I2 statistics. Publication bias was assessed using Begg and Egger tests. We calculated the odds ratio (OR) or risk ratio (RR) with a 95% confidence interval (CI) using a random-effects model.

RESULTS

Of 11 034 studies retrieved from the search, 56 studies (including 10 568 091 participants) were eligible. The ORs (95% CI) of low (<2500 g) versus normal birthweight (2500-4000 g) and childhood cancers were as follows: leukemia, 0.92 (0.77-1.11); acute lymphoblastic leukemia, 0.82 (0.72-0.94); acute myeloid leukemia, 0.98 (0.77-1.24); lymphoma, 0.99 (0.47-2.10); Hodgkin, 0.79 (0.61-1.03); non-Hodgkin, 0.85 (0.60-1.20); neuroblastoma, 1.34 (1.14-1.58); retinoblastoma, 0.95 (0.68-1.32); rhabdomyosarcoma, 0.86 (0.61-1.20); embryonal, 0.97 (0.66-1.43); alveolar, 1.92 (0.43-8.51); and Wilms tumor, 1.01 (0.83-1.24). The ORs (95% CI) of high (>4000 g) versus normal birthweight and childhood cancers were as follows: leukemia, 1.30 (1.18-1.42); acute lymphoblastic leukemia, 1.27 (1.16-1.39); acute myeloid leukemia, 1.13 (0.98-1.30); lymphoma, 1.69 (0.72-3.94); Hodgkin, 1.22 (1.02-1.46); non-Hodgkin, 1.22 (0.80-1.86); neuroblastoma, 1.20 (1.02-1.41); retinoblastoma, 1.17 (0.93-1.48); rhabdomyosarcoma, 1.07 (0.90-1.27); embryonal, 1.22 (1.00-1.49); alveolar, 1.02 (0.46-2.27); and Wilms tumor, 1.49 (1.34-1.67).

CONCLUSION

This meta-analysis identified high birth weight as a potential risk factor for some childhood cancers, while low birth weight might be protective against a few.

Association of birth weight with cancer risk: a dose-response meta-analysis and Mendelian randomization study

BACKGROUND

Several articles have shown that birth weight is associated with the risk of many types of cancers. However, the results are inconsistent, and whether the relationship has a causal effect remains unknown.

METHODS

We searched the PubMed and Embase libraries up to March 2021 and selected observational studies reporting the relationship between birth weight and adult-onset cancer risk. Dose-response meta-analysis and two-sample Mendelian randomization (MR) analysis were used to estimate the effect.

RESULT

In our dose-response meta-analysis, six cancers from 46 studies were found to have significant associations with birth weight. (Ovarian cancer: RR: 1.21, 95% CI 1.01-1.44; breast cancer: RR: 1.12, 95% CI 1.08-1.16; colorectal cancer: RR: 1.20, 95% CI 1.01-1.43; endometrial cancer: RR: 0.85, 95% CI 0.78-0.93; prostate cancer: RR: 1.27, 95% CI 1.01-1.61; testicular cancer: RR: 1.21, 95% CI 1.03-1.43). As birth weight increased, the slope of the dose-response curve of breast cancer increased continuously, and the curve of testicular cancer was U-shaped. In the MR study, seven cancers were included. Only invasive mucinous ovarian cancer was found to have a causal effect on birth weight (OR: 0.62; 95% CI 0.39-0.97), while other cancers did not.

CONCLUSIONS

Our findings suggest that birth weight are unlikely to have a casual effect on risk of cancers via the MR analysis, although the dose-response meta-analysis shows that there is a nonlinear relationship between birth weight and breast cancer and testicular cancer. More relevant researches are needed to further investigate their effect.

Maternal exposure to an n-3 polyunsaturated fatty acid diet decreases mammary cancer risk of female offspring in adulthood

Maternal exposure to dietary factors during pregnancy influences the risk of many adult-onset diseases in the later life of offspring. Here, we investigated the effects of maternal n-3 polyunsaturated fatty acid (PUFA) diet on breast cancer risk of female offspring. Pregnant C57BL/6J mice were fed a normal diet (control group), or a high-fat diet rich in safflower oil (SO), fish oil (FO) or flaxseed oil (FSO) (n = 10) throughout gestation and lactation. Their female offspring were fed an AIN-93G diet from weaning. Tumor incidences in offspring induced by 7,12-dimethylbenz[α]anthracene (DMBA) were higher in high-fat groups than in the control group, and were lower in FO and FSO groups than in the SO group. The plasma concentrations of 17β-estradiol (E2), in both pregnant dams and offspring, were significantly lower in FO and FSO groups compared with the SO group. The FO and FSO offspring showed delayed puberty onset, and their mammary glands contained decreased numbers of epithelial terminal end buds (TEBs, targets for malignant transformation) compared with SO offspring. Reduced cell proliferation and increased apoptosis in FO and FSO offspring were observed compared with SO offspring. In line with these changes, maternal exposure to FO promoted the expression of long noncoding RNA (lncRNA) in p53 and apoptosis signaling pathways and inhibited that in NF-κB and Jak-STAT signaling pathways, while FSO promoted the expression of lncRNA in p53 signaling pathways and inhibited that in NF-κB, Jak-STAT and MAPK signaling pathways. In conclusion, maternal exposure to a high-fat diet rich in n-3 PUFAs, both marine- and plant-based, has a protective effect on mammary tumor risk of female offspring in later life.

Breast cancer protection by genomic imprinting in close kin families

Human inbreeding generally reduces breast cancer risk (BCR). When the parents are biologically related, their infants have a lower birth weight due to smaller body organs. The undersized breasts, because of fewer mammary stem cells, have a lower likelihood of malignant conversion. Fetal growth is regulated by genomically imprinted genes which are in conflict; they promote growth when derived from the father and suppress growth when derived from the mother. The kinship theory explicates that the intensity of conflict between these genes affects growth and therefore the size of the newborn. In descendants of closely related parents, this gene clash is less resulting in a smaller infant. In this review, we elucidate the different mechanisms by which human inbreeding affects BCR, and why this risk is dissimilar in different inbred populations.

Pre-natal exposures and breast tissue composition: findings from a British pre-birth cohort of young women and a systematic review

BACKGROUND

Breast density, the amount of fibroglandular tissue in the adult breast for a women's age and body mass index, is a strong biomarker of susceptibility to breast cancer, which may, like breast cancer risk itself, be influenced by events early in life. In the present study, we investigated the association between pre-natal exposures and breast tissue composition.

METHODS

A sample of 500 young, nulliparous women (aged approximately 21 years) from a U.K. pre-birth cohort underwent a magnetic resonance imaging examination of their breasts to estimate percent water, a measure of the relative amount of fibroglandular tissue equivalent to mammographic percent density. Information on pre-natal exposures was collected throughout the mothers' pregnancy and shortly after delivery. Regression models were used to investigate associations between percent water and pre-natal exposures. Mediation analysis, and a systematic review and meta-analysis of the published literature, were also conducted.

RESULTS

Adjusted percent water in young women was positively associated with maternal height (p for linear trend [p t] = 0.005), maternal mammographic density in middle age (p t = 0.018) and the participant's birth size (p t < 0.001 for birthweight). A 1-SD increment in weight (473 g), length (2.3 cm), head circumference (1.2 cm) and Ponderal Index (4.1 g/cm3) at birth were associated with 3 % (95 % CI 2-5 %), 2 % (95 % CI 0-3 %), 3 % (95 % CI 1-4 %) and 1 % (95 % CI 0-3 %), respectively, increases in mean adjusted percent water. The effect of maternal height on the participants' percent water was partly mediated through birth size, but there was little evidence that the effect of birthweight was primarily mediated via adult body size. The meta-analysis supported the study findings, with breast density being positively associated with birth size.

CONCLUSIONS

These findings provide strong evidence of pre-natal influences on breast tissue composition. The positive association between birth size and relative amount of fibroglandular tissue indicates that breast density and breast cancer risk may share a common pre-natal origin.

Endocrine controls of primary adult human stem cell biology: thyroid hormones stimulate keratin 15 expression, apoptosis, and differentiation in human hair follicle epithelial stem cells in situ and in vitro

Here we demonstrate that physiological concentrations of the thyroid hormones T3 and T4 enhance the KERATIN 15 promoter activity and expression in epithelial stem cells of adult human scalp hair follicles in situ and in vitro. Additionally, T3 and T4 stimulate expression of the immuno-inhibitory surface molecule CD200. Subsequently, T3 and T4 induce apoptosis and differentiation and inhibit clonal growth of these progenitor cells in vitro. These data suggest that human hair follicle bulge-derived epithelial stem cells underlie profound, previously unknown hormonal regulation by thyroid hormones, and show that primary human keratin 15-GFP+ progenitor cells can be exploited to further elucidate fundamental endocrine controls of human epithelial stem cells.

Developmental exposure to estradiol and bisphenol A increases susceptibility to prostate carcinogenesis and epigenetically regulates phosphodiesterase type 4 variant 4

Early developmental perturbations have been linked to adult-onset prostate pathology, including excessive exposure to estrogenic compounds; however, the molecular basis for this imprinting event is not known. An important and controversial health concern is whether low-dose exposures to hormonally active environmental estrogens, such as bisphenol A, can promote human diseases, including prostate cancer. Here, we show that transient developmental exposure of rats to low, environmentally relevant doses of bisphenol A or estradiol increases prostate gland susceptibility to adult-onset precancerous lesions and hormonal carcinogenesis. We found permanent alterations in the DNA methylation patterns of multiple cell signaling genes, suggesting an epigenetic basis for estrogen imprinting. For phosphodiesterase type 4 variant 4 (PDE4D4), an enzyme responsible for cyclic AMP breakdown, a specific methylation cluster was identified in the 5'-flanking CpG island that was gradually hypermethylated with aging in normal prostates, resulting in loss of gene expression. Early and prolonged hypomethylation at this site following neonatal estradiol or bisphenol A exposure resulted in continued, elevated PDE4D4 expression. Cell line studies confirmed that site-specific methylation is involved in transcriptional silencing of the PDE4D4 gene and showed hypomethylation of this gene in prostate cancer cells. Importantly, the PDE4D4 alterations in the estrogen-exposed prostates were distinguishable before histopathologic changes of the gland, making PDE4D4 a candidate molecular marker for prostate cancer risk assessment as a result of endocrine disruptors. In total, these findings indicate that low-dose exposures to ubiquitous environmental estrogens affect the prostate epigenome during development and, in so doing, promote prostate disease with aging.