Abstract High childhood and adolescent dietary intake of isoflavone genistein (GEN) in soyfoods reduces later breast cancer risk, but since GEN has estrogenic properties, it is not clear whether it is safe to start consuming it after breast cancer has been diagnosed. Using a new preclinical model, we investigated the effects of childhood, adult and/or post-diagnosis consumption of GEN on the ability of tamoxifen (TAM) to treat breast cancer. 95 female Sprague-Dawley rats consuming AIN93G diet were supplemented with 0 or 500 ppm GEN between postnatal days (PND) 15 to 30 (prepubertal exposure) and then were fed AIN93G diet with no GEN between PND 30 and 55. On PND 48, rats received 10 mg DMBA to induce mammary tumors, and were then divided to four dietary groups on PND 55: prepubertal GEN-adult GEN group (GG, n=20); prepubertal GEN-adult control group (GC, n=20); prepubertal control-adult GEN (CG, n=20); and control-control (CC, n=35). When mammary tumor reached a size of 1.4 cm in diameter, 337 ppm TAM was added to rats’ diet. GG and CG rats continued also consuming GEN, and all rats in GC and 20 rats in CC groups stated consuming GEN one week after the TAM treatment started. 15 CC rats were never fed GEN. Mammary tumor latency was longer in GG (p<0.003) and GC rats (p<0.095), compared to CC rats. The response of tumors to TAM treatment was classified as complete or partial response, or de novo resistant. Prepubertal and life-time GEN intake increased, and intake starting during TAM treatment reduced response to TAM (p<0.001). Mammary cancer recurrence rate was highest in the rats which started consuming GEN during TAM treatment, and significantly lower in life-time, prepubertal and adulthood only GEN intake groups (p<0.001). Brca1 mRNA level was highest in the mammary gland of life-time GEN consuming rats (p<0.05). Tumor suppressor genes p21WAF1/CIP1 and p16INK4a mRNA levels were significantly higher in both prepubertal GEN groups (GC and GG) than in CC rats (p<0.05), as was the expression of pro-apoptotic gene Bax (p<0.05). No changes in estrogen receptor (ER) protein expression in the mammary gland were seen among the groups, but progesterone receptor (p<0.05) and phosphorylated HER2/ErbB2 (p<0.05) were both expressed at a lower level in rats consuming GEN through the life-time, compared with rats which consumed GEN during adult life (CG rats). Our findings show that rats exposed prepubertally or through the life-time to GEN were at lower risk of developing TAM resistance than rats which started GEN intake in adulthood or post-diagnosis. The effect of prepubertal GEN exposure in increasing TAM responsiveness may be related to up-regulation of tumor suppressor genes Brca1, p16INK4a and p21WAF1/CIP1 in their mammary gland. Recurrence rate was highest in those rats that were consuming GEN for the first time during TAM treatment. If true for humans, women with ER+ breast cancer should not start consuming GEN during TAM treatment. Citation Format: Xiyuan Zhang, Anni Warri, Idalia Cruz, Robert Clarke, Leena A. Hilakivi-Clarke. Lifetime and adulthood dietary genistein intake have opposing effect on tamoxifen resistance in rats. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 196. doi:10.1158/1538-7445.AM2013-196
The advent of high-throughput DNA methylation profiling techniques has enabled the possibility of accurate identification of differentially methylated genes for cancer research. The large number of measured loci facilitates whole genome methylation study, yet posing great challenges for differential methylation detection due to the high variability in tumor samples.We have developed a novel probabilistic approach, D: ifferential M: ethylation detection using a hierarchical B: ayesian model exploiting L: ocal D: ependency (DM-BLD), to detect differentially methylated genes based on a Bayesian framework. The DM-BLD approach features a joint model to capture both the local dependency of measured loci and the dependency of methylation change in samples. Specifically, the local dependency is modeled by Leroux conditional autoregressive structure; the dependency of methylation changes is modeled by a discrete Markov random field. A hierarchical Bayesian model is developed to fully take into account the local dependency for differential analysis, in which differential states are embedded as hidden variables. Simulation studies demonstrate that DM-BLD outperforms existing methods for differential methylation detection, particularly when the methylation change is moderate and the variability of methylation in samples is high. DM-BLD has been applied to breast cancer data to identify important methylated genes (such as polycomb target genes and genes involved in transcription factor activity) associated with breast cancer recurrence.A Matlab package of DM-BLD is available at http://www.cbil.ece.vt.edu/software.htm CONTACT: Xuan@vt.eduSupplementary information: Supplementary data are available at Bioinformatics online.
Breast cancers characterized by expression of estrogen receptor-alpha; ESR1) represent approximately 70% of all new cases and comprise the largest molecular subtype of this disease. Despite this high prevalence, the number of adequate experimental models of ER+ breast cancer is relatively limited. Nonetheless, these models have proved very useful in advancing understanding of how cells respond to and resist endocrine therapies, and how the ER acts as a transcription factor to regulate cell fate signaling. We discuss the primary experimental models of ER+ breast cancer including 2D and 3D cultures of established cell lines, cell line- and patient-derived xenografts, and chemically induced rodent models, with a consideration of their respective general strengths and limitations. What can and cannot be learned easily from these models is also discussed, and some observations on how these models may be used more effectively are provided. Overall, despite their limitations, the panel of models currently available has enabled major advances in the field, and these models remain central to the ability to study mechanisms of therapy action and resistance and for hypothesis testing that would otherwise be intractable or unethical in human subjects.
Abstract Inadequate social contacts and loneliness, often referred to as social isolation (SI), are associated with increased mortality from many diseases, including breast cancer. Up to 41% of breast cancer patients have been identified as feeling socially isolated. Moreover, socially isolated breast cancer survivors have a 43% higher risk of recurrence than socially integrated survivors. To prevent increased mortality, biological mechanisms which mediate the effects of SI on cancer need to be identified. One unexplored, but possible mechanism is through the gut microbiota. Through bidirectional interactions, the gut is affected by stress and the gut microbiota in turn can modulate stress response, host immunity and metabolism. Here we tested the hypothesis that SI induces gut dysbiosis. In our study, repeated in four separate experiments, adult female mice were divided into two groups – those kept group housed (GH, 4 mice per cage) and those housed singly in SI for 4 weeks. Several differences in the gut microbial family, genus and species levels were seen, but the differences were mostly unique to each of the four experiment. Beta-diversity was increased in three of the four studies in SI mice. Since beta-diversity is increased by aging, SI may accelerate the aging process. At the genus level, SI significantly suppressed the abundance of Akkermansia in all four studies and increased Acetatifactor in three studies. These two bacterial changes are expected to disrupt mitochondrial oxidative phosphorylation (OXPHOS), most likely by suppressing the short-chain fatty acid production. Further, low Akkermansia and high Acetatifactor are expected to increase inflammation. In a separate study, we discovered that SI impaired OXPHOS and activated inflammatory pathways in the mammary gland. We also have assessed immune cells in the spleen. SI increased the frequency of pro-inflammatory CD4+RORy+ cells, and the immunosuppressive Treg (CD4+Foxp3+) and PMN-MDSCs cells. In addition, SI increased PD1 expression in Foxp3+ cells, suggesting that anti-PD1 therapy might adversely affect socially isolated breast cancer patients by invigorating Treg cells. We are currently studying if the changes in the gut microbiota in SI mice are causally linked to their impaired mitochondrial metabolism, immunosuppression and increased mammary cancer mortality. We also plan to investigate if dietary modifications can reverse gut dysbiosis in SI mice and prevent their increased mortality from mammary cancer. Citation Format: Fabia de Oliveira Andrade, Lu Jin, Vivek Verma, Maddie McDermott, Chris Staley, Leena Hilakivi-Clarke. Social isolation induces gut dysbiosis, mitochondrial metabolic dysfunction, and infiltration of tumor immunosuppressive cells: do they explain enhanced mammary tumorigenesis? [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-05-16.
Abstract More than 50% of pregnant women in the USA are overweight or obese, and over 40% gain more weight than recommended by the Institute of Medicine. We investigated if maternal obesity before and during pregnancy affects mammary cancer risk in the offspring, or alters response of the mammary tumors to antiestrogen therapy in a preclinical rat model of estrogen receptor positive (ER+) breast cancer. Female Sprague-Dawley rats were fed an obesity-inducing high fat (OIHF) or control diet before and during pregnancy. Their offspring were all switched to a control AIN93G diet upon birth. Female offspring of control (n = 35) or OIHF (n = 40) diet fed dams were treated with a carcinogen DMBA on postnatal day 50 to induce ER+ mammary tumors. When mammary tumors reached a size of 13 mm in diameter, 337 ppm TAM citrate was added to the offspring's diet, resulting a daily intake of 15 mg/kg TAM. Responses of the tumors were categorized as de novo resistant (tumor kept growing), partial (size decreased but did not disappear), and complete (tumor disappeared). The animals with complete response were taken off from TAM and monitored for an additional 20 weeks to determine the risk of local recurrence. The risk of developing mammary tumors was non-significantly increased in the OIHF group. Further, the OIHF exposed offspring had significantly more de novo resistant tumors than the control offspring. Although the percentage of completely responding tumors was similar in the two groups, local recurrence in the OIHF offspring was significantly higher than in the control offspring (90% vs 29%, respectively). To investigate the possible mechanisms of increased recurrence, we measured the protein levels of the members of unfolded protein response (UPR), inflammation and tumor immune pathways. We found that de novo TAM resistant and recurring tumors in the OIHF offspring exhibited significantly increased levels of Perk and Beclin-1, indicating activation of UPR. However, Nbr1 and p62 were also significantly increased in the OIHF offspring, suggestive of inhibition of autophagy in their mammary tumors. The levels of CD8a, a marker of cytotoxic T cells, were significantly reduced, whilst ERα, erBb2/Her2 and Vegfr2 were increased. Changes in the expression of these receptors could indicate increased inflammation. We conclude that maternal obesity increased TAM resistance and the risk of mammary cancer recurrence in the female offspring. In addition, it induced changes in the UPR, autophagy and tumor immune responses in the offspring's mammary tumors. Citation Format: Xiyuan Zhang, Idalia Cruz, Hansheng Zhang, Leena Hilakivi-Clarke. Maternal obesity increases tamoxifen resistance in female rat offspring. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4322.
Tamoxifen has been prescribed to millions of females for breast cancer prevention or treatment. However, tamoxifen is known to significantly enhance the risk of developing endometrial lesions, including hyperplasia, polyps, carcinomas, and sarcoma. Notably, tamoxifen-associated endometrial cancer often has a poor clinical outcome. Understanding the molecular mechanism of tamoxifen-induced endometrial cancer is essential for developing strategies that minimize tamoxifen's effects on the endometrium without jeopardizing its breast cancer treatment effects. However, this understanding remains limited. Tamoxifen appears to mediate its effect on endometrial cells through estrogenic and non-genomic pathways, rather than introducing a genomic alteration as a carcinogen. Although tamoxifen functions as an agonist and promotes cell proliferation in endometrial cancer, it also displays antagonist activity towards some estrogen targets. Alterations in estrogen receptor-α and its isoforms, as well as the membrane associated estrogen receptor G protein-coupled receptor 30, have been observed with tamoxifen-exposed endometrial cells, and likely mediate the effects of tamoxifen on endometrial cancer cell proliferation and invasion. In addition, gene profile studies of short-term exposure to tamoxifen indicate that the majority of tamoxifen targets are tamoxifen-specific. However, the tamoxifen regulated gene targets that are involved in mediating the effects of long-term exposure to tamoxifen are not yet fully understood. Recent progress has indicated a potential role of unfolded protein response and mammalian target of rapamycin signaling in tamoxifen-associated endometrial cancer. In the future, studies focusing on long-term effects of tamoxifen exposure are required to understand the molecular mechanisms of tamoxifen-associated endometrial cancer.
