Interaction Between Estrogen Receptor Alpha, Ionizing Radiation and (anti-) Estrogens in Breast Cancer Cells

The prognostic value of cyclin D1 in breast cancer patients treated with hormonal therapy: A pilot study

THE AIM

of the study was to determine the clinical relevance of cyclin D1 (cD1) and its association with clinicopathological parameters in breast cancer patients treated with hormonal therapy.

MATERIAL AND METHODS

The study included 96 primary breast cancer patients with known clinicopathological parameters. In adjuvant setting, 44 patients were tamoxifen-treated and 52 were treated with ovarian irradiation/ablation. The cD1 status (gene amplified/nonamplified) was determined on formalin-fixed paraffin-embedded tumor tissue sections by chromogenic in situ hybridization. Associations between parameters were analyzed by Chi-square and Spearman's rank order correlation tests. Cox proportional hazards regression test was performed. Survival curves for relapse-free survival were constructed according to the Kaplan-Meier method.

RESULTS

There were no significant associations between cyclin D1 and clinicopathological parameters in either patient group. Amplified cyclin D1 associated significantly with the actual relapse incidence in the ovarian ablation patient group (p = 0.01, HR = 3.1), but not in the tamoxifen-treated patient group. Estrogen receptor and cyclin D1 have proven to be independent parameters of poor outcome in the ovarian ablation patient group (p = 0.03, HR = 2.9; and p = 0.009, HR = 2.5; respectively).

CONCLUSIONS

Cyclin D1 might be a candidate biomarker of poor outcome in breast cancer patients treated with ovarian ablation, suggesting its possible involvement in acquirement of hormonal resistance. The role of cyclin D1 as potential parameter of response to tamoxifen was not as pronounced.

Concomitant DNA methylation and transcriptome signatures define epidermal responses to acute solar UV radiation

The simultaneous analysis of different regulatory levels of biological phenomena by means of multi-omics data integration has proven an invaluable tool in modern precision medicine, yet many processes ultimately paving the way towards disease manifestation remain elusive and have not been studied in this regard. Here we investigated the early molecular events following repetitive UV irradiation of in vivo healthy human skin in depth on transcriptomic and epigenetic level. Our results provide first hints towards an immediate acquisition of epigenetic memories related to aging and cancer and demonstrate significantly correlated epigenetic and transcriptomic responses to irradiation stress. The data allowed the precise prediction of inter-individual UV sensitivity, and molecular subtyping on the integrated post-irradiation multi-omics data established the existence of three latent molecular phototypes. Importantly, further analysis suggested a form of melanin-independent DNA damage protection in subjects with higher innate UV resilience. This work establishes a high-resolution molecular landscape of the acute epidermal UV response and demonstrates the potential of integrative analyses to untangle complex and heterogeneous biological responses.

Impact of adjuvant hormonotherapy on radiation-induced breast fibrosis according to the individual radiosensitivity: results of a multicenter prospective French trial

BACKGROUND

To evaluate risk of severe breast fibrosis occurrence in patients treated by breast-conserving surgery, adjuvant radiotherapy and hormonotherapy (HT) according to individual radiosensitivity (RILA assay).

RESULTS

HT- and RILAhigh were the two independent factors associated with improved breast-fibrosis free survival (BFFS). BFFS rate at 36 months was lower in patients with RILAlow and HT+ than in patients with RILAhigh and HT- (75.8% and 100%, respectively; p = 0.004, hazard ratio 5.84 [95% confidence interval (CI) 1.8-19.1]). Conversely, BFFS at 36 months was comparable in patients with RILAhigh and HT+ and in patients with RILAlow and HT- (89.8% and 93.5%, respectively; p = 0.39, hazard ratio 1.7 [95% CI 0.51-5.65]), showing that these two parameters influenced independently the occurrence of severe breast fibrosis. BFFS rate was not affected by the HT type (tamoxifen or aromatase inhibitor) and timing (concomitant or sequential with radiotherapy).

CONCLUSIONS

HT and RILA score independently influenced BFFS rate at 36 months. Patients with RILAhigh and HT- presented an excellent BFFS at 36 months (100%).

MATERIALS AND METHODS

Breast Fibrosis-Free Survival (BFFS) rate was assessed relative to RILA categories and to adjuvant HT use (HT+ and HT-, respectively) in a prospective multicentre study (NCT00893035) which enrolled 502 breast cancer patients (456 evaluable patients). Breast fibrosis was recorded according to CTCAE v3.0 grading scale; RILA score was defined according to two categories (<12%: RILAlow; ≥12%: RILAhigh).

Estrogen Receptor Signaling in Radiotherapy: From Molecular Mechanisms to Clinical Studies

Numerous studies have established a proof of concept that abnormal expression and function of estrogen receptors (ER) are crucial processes in initiation and development of hormone-related cancers and also affect the efficacy of anti-cancer therapy. Radiotherapy has been applied as one of the most common and potent therapeutic strategies, which is synergistic with surgical excision, chemotherapy and targeted therapy for treating malignant tumors. However, the impact of ionizing radiation on ER expression and ER-related signaling in cancer tissue, as well as the interaction between endocrine and irradiation therapy remains largely elusive. This review will discuss recent findings on ER and ER-related signaling, which are relevant for cancer radiotherapy. In addition, we will summarize pre-clinical and clinical studies that evaluate the consequences of anti-estrogen and irradiation therapy in cancer, including emerging studies on head and neck cancer, which might improve the understanding and development of novel therapeutic strategies for estrogen-related cancers.

Radiotherapy for cervical cancer - impact on the vaginal epithelium and sexual function

BACKGROUND

Women who have been treated for cervical cancer have persistent changes in their sexual function, which result in considerable distress. The aim of this study was to investigate the morphology of the vaginal epithelium in cervical cancer survivors treated with radiotherapy and its correlation to serum levels of sex steroid hormones and sexual function.

MATERIAL AND METHODS

We included 34 patients treated for cervical cancer with radiotherapy and 37 healthy age-matched control women scheduled for benign gynecological surgery. After inspection and grading of vaginal atrophy, vaginal biopsies were taken. Epithelial structures were analyzed by measuring epithelial thickness as well as the number, height and width of the dermal papillae and the dermal papillae distance. Sex steroid hormone levels were analyzed and a questionnaire designed to assess sexual function was filled out.

RESULTS

In the cervical cancer survivors treated with radiotherapy, the vaginal epithelium volume was reduced compared to control women. Longer distance between the dermal papillae (p < .001) and a shorter distance from basal layer to epithelial surface (p < .05) were measured. Mucosal atrophy was observed in 91% of the survivors. There was no difference in serum estradiol between cancer survivors and control women, implying that the cancer survivors were sufficiently substituted. The epithelial thickness correlated to serum levels of estradiol. The cervical cancer survivors reported more physical sexual symptoms. The highest relative risk (RR) was found for insufficient vaginal lubrication (RR 12.6), vaginal inelasticity (RR 6.5), reduced genital swelling when sexually aroused (RR 5.9), and for reduction of vaginal length during intercourse (RR 3.9).

CONCLUSION

We found that cervical cancer treatment including radiotherapy is associated with vaginal epithelial atrophy and sexual dysfunction. To hamper the atrophic process affecting the sexual function, an early start of local estrogen after therapy might be of importance.

Trastuzumab improves locoregional control in HER2-positive breast cancer patients following adjuvant radiotherapy

The benefit of adjuvant trastuzumab in disease-free and overall survival for human epidermal receptor 2-positive (HER2+) breast cancer patients is well established. However, the effect of trastuzumab on locoregional control remains unclear, particularly in patients treated with adjuvant radiotherapy (RT). In this study, we investigated the locoregional benefit of trastuzumab in patients with HER2+ breast cancer after adjuvant RT.Using a single institutional database, we identified 278 patients with stage II/III invasive HER2+ breast tumors receiving adjuvant RT between January 2008 and July 2011. We compared the locoregional outcomes of 134 patients who received trastuzumab to 144 patients without trastuzumab within the same period. Clinical and biological factors that might impact on the locoregional benefit of trastuzumab were also assessed.At the median follow-up of 45 months, trastuzumab significantly lowered the risk of locoregional recurrence (LRR) with a 3-year LRR rate of 2.4% versus 7.5% for the cohort with and without trastuzumab (P = 0.019). Trastuzumab was associated with a more significant locoregional benefit in the hormone receptor-positive (HR+)/HER2+ subgroup, with a 3-year LRR of 0% versus 6.7% in the cohort with and without trastuzumab (P = 0.027). For HR-/HER2+ breast tumor patients, the 3-year LRR rate was still lower for the cohort with trastuzumab (4.7% vs 8.6%). However, statistical significance was not found (P = 0.179). Both univariate and multivariate analyses confirmed that trastuzumab treatment was the only significant predictive factor for LRR (hazard ratio, 4.05; 95% confidence interval, 1.07-15.35; P = 0.039).Adjuvant trastuzumab in addition to RT is associated with significant reduced LRR risk in HER2+ breast cancer.

Synthetic genistein glycosides inhibiting EGFR phosphorylation enhance the effect of radiation in HCT 116 colon cancer cells

The need to find new EGFR inhibitors for use in combination with radiotherapy in the treatment of solid tumors has drawn our attention to compounds derived from genistein, a natural isoflavonoid. The antiproliferative potential of synthetic genistein derivatives used alone or in combination with ionizing radiation was evaluated in cancer cell lines using clonogenic assay. EGFR phosphorylation was assessed with western blotting. Genistein derivatives inhibited clonogenic growth of HCT 116 cancer cells additively or synergistically when used in combination with ionizing radiation, and decreased EGFR activation. Our preclinical evaluation of genistein-derived EGFR inhibitors suggests that these compounds are much more potent sensitizers of cells to radiation than the parent isoflavonoid, genistein and indicate that these compounds may be useful in the treatment of colon cancer with radiation therapy.

Estrogen signaling and the DNA damage response in hormone dependent breast cancers

Estrogen is necessary for the normal growth and development of breast tissue, but high levels of estrogen are a major risk factor for breast cancer. One mechanism by which estrogen could contribute to breast cancer is via the induction of DNA damage. This perspective discusses the mechanisms by which estrogen alters the DNA damage response (DDR) and DNA repair through the regulation of key effector proteins including ATM, ATR, CHK1, BRCA1, and p53 and the feedback on estrogen receptor signaling from these proteins. We put forward the hypothesis that estrogen receptor signaling converges to suppress effective DNA repair and apoptosis in favor of proliferation. This is important in hormone-dependent breast cancer as it will affect processing of estrogen-induced DNA damage, as well as other genotoxic insults. DDR and DNA repair proteins are frequently mutated or altered in estrogen responsive breast cancer, which will further change the processing of DNA damage. Finally, the action of estrogen signaling on DNA damage is also relevant to the therapeutic setting as the suppression of a DDR by estrogen has the potential to alter the response of cancers to anti-hormone treatment or chemotherapy that induces DNA damage.

Interaction between ionizing radiation and estrogen: what we are missing?

Following complexity as a new approach in science of 21st century biomonitoring of biological effects caused by ionizing radiation received an option of a new dimension. Insight in biological response of mammals to ionizing radiation exposure by integration of genome, non-genome and distant organ bystander effects will significantly change evaluation of health risk and preventive measures. Impact of estrogen on carcinogenesis caused by occupational or accidental exposure to ionizing radiation additionally enables biodosimetry to recognize vulnerable subpopulations according to gender and age. Estrogen, as a potent molecule involved in number of biological pathways during development and adulthood, shows close interaction with pathological processes launched by overexposure to ionizing radiation which should be included in future research and radiation protection.

Concurrent hormone and radiation therapy in patients with breast cancer: what is the rationale?

Endocrine therapy is often given together with postoperative radiotherapy in patients with breast cancer and positive hormone-receptor status. However, few experimental or clinical studies address the combined effects of hormone and radiation therapy. Preclinical models have shown changes in tumour cell kinetics with the addition of tamoxifen, and some show reduced tumour cell death with concurrent anti-oestrogen treatment and radiotherapy. Although data from in-vitro studies support the notion of antagonistic effects of concurrent tamoxifen and radiotherapy on tumour cells, in-vivo research suggests a synergistic effect that could be attributable to micro-environmental changes in tumour responsiveness to ionising radiation and hormone therapy. Retrospective studies suggest that in practical application, concurrent administration of tamoxifen with radiotherapy does not compromise local control but might increase toxicity. Preliminary results from simultaneous treatment with aromatase inhibitors and radiation indicate that this combination of endocrine and radiation therapy could enhance cytotoxicity and improve tumour response. Further studies are needed to clarify the physiological mechanisms activated by oestrogens, which will allow a more thorough understanding of the complex interactions between 17beta-oestradiol and P53/P21(WAF1/CIP1)/Rb pathways and of the interaction between endocrine therapy and radiotherapy.

Adenovirus-mediated expression of Tob1 sensitizes breast cancer cells to ionizing radiation

AIM

To investigate the effect of the Tob1 gene, a member of the Transducing Molecule of ErbB2/B-cell Translocation Ggene (TOB/BTG) family, by using the adenovirus-mediated expression of Tob1 on radiosensitivity in a human breast cancer cell line MDA-MB-231.

METHODS

Cell survival was determined by clonogenic assay. Apoptosis was evaluated by DNA fragmentation gel electrophoresis and terminal deoxynucleotidyl transferase-mediated nick end labeling assay. Protein expression was analyzed by Western blot assay and DNA repair was measured by a host cell reactivation assay.

RESULTS

We demonstrated that pre-irradiation treatment with Ad5-Tob1 significantly increased radiosensitivity, accompanying the increased induction of apoptosis and the repression of DNA damage repair. Furthermore, Ad5-Tob1-mediated radiosensitivity correlates with the upregulation of the pro-apoptotic protein Bax and the downregulation of several DNA double strand break repair proteins, including DNA-dependent protein kinases, Ku70 and Ku80, and X-ray-sensitive complementation group 4.

CONCLUSION

Tob1, as a new radiosensitizer, is a new target in the radiotherapy of breast cancer via increasing apoptosis and suppressing DNA repair.

Estrogens decrease γ-ray–induced senescence and maintain cell cycle progression in breast cancer cells independently of p53

PURPOSE

Sequential administration of radiotherapy and endocrine therapy is considered to be a standard adjuvant treatment of breast cancer. Recent clinical reports suggest that radiotherapy could be more efficient in association with endocrine therapy. The aim of this study was to evaluate the estrogen effects on irradiated breast cancer cells (IR-cells).

METHODS AND MATERIALS

Using functional genomic analysis, we examined the effects of 17-beta-estradiol (E(2), a natural estrogen) on MCF-7 breast cancer cells.

RESULTS

Our results showed that E(2) sustained the growth of IR-cells. Specifically, estrogens prevented cell cycle blockade induced by gamma-rays, and no modification of apoptotic rate was detected. In IR-cells we observed the induction of genes involved in premature senescence and cell cycle progression and investigated the effects of E(2) on the p53/p21(waf1/cip1)/Rb pathways. We found that E(2) did not affect p53 activation but it decreased cyclin E binding to p21(waf1/cip1) and sustained downstream Rb hyperphosphorylation by functional inactivation of p21(waf1/cip1). We suggest that Rb inactivation could decrease senescence and allow cell cycle progression in IR-cells.

CONCLUSION

These results may help to elucidate the molecular mechanism underlying the maintenance of breast cancer cell growth by E(2) after irradiation-induced damage. They also offer clinicians a rational basis for the sequential administration of ionizing radiation and endocrine therapies.