Antihormone induced compensatory signalling in breast cancer: an adverse event in the development of endocrine resistance

The potential of epigenetic therapy to target the 3D epigenome in endocrine-resistant breast cancer

Three-dimensional (3D) epigenome remodeling is an important mechanism of gene deregulation in cancer. However, its potential as a target to counteract therapy resistance remains largely unaddressed. Here, we show that epigenetic therapy with decitabine (5-Aza-mC) suppresses tumor growth in xenograft models of pre-clinical metastatic estrogen receptor positive (ER+) breast tumor. Decitabine-induced genome-wide DNA hypomethylation results in large-scale 3D epigenome deregulation, including de-compaction of higher-order chromatin structure and loss of boundary insulation of topologically associated domains. Significant DNA hypomethylation associates with ectopic activation of ER-enhancers, gain in ER binding, creation of new 3D enhancer-promoter interactions and concordant up-regulation of ER-mediated transcription pathways. Importantly, long-term withdrawal of epigenetic therapy partially restores methylation at ER-enhancer elements, resulting in a loss of ectopic 3D enhancer-promoter interactions and associated gene repression. Our study illustrates the potential of epigenetic therapy to target ER+ endocrine-resistant breast cancer by DNA methylation-dependent rewiring of 3D chromatin interactions, which are associated with the suppression of tumor growth.

Effect of Graves' disease on the prognosis of differentiated thyroid carcinoma: a meta-analysis

PURPOSE

Several studies have reported different findings on the prognosis of differentiated thyroid carcinoma combined with Graves' disease. To assess the effect of Graves' disease on differentiated thyroid carcinoma, a meta-analysis was undertaken.

METHODS

PubMed, OVID and the Cochrane Library were systematically searched for trials published prior to Oct. 2018. Studies containing data on the outcomes of Graves' disease with differentiated thyroid carcinoma were included. Summary estimates of the prevalence of recurrence/disease progression/persistence and mortality as well as odds ratios and weighted mean differences were calculated with a random-effects model.

RESULTS

Of the 916 related articles found, 13 fulfilled the inclusion criteria. The recurrence/disease progression/persistent rate was not significantly different between the Graves' disease group and the non-Graves' disease group (P = 0.86). However, the analysis of three studies with K-M curves or HRs showed that there was a significant difference between the two groups (P = 0.04). Subgroup analysis showed that the contradictory results could be due to the location/race assessed in the studies. Graves' disease almost acted as a risk factor (OR = 1.77, 95%C.I. = 0.99-3.16) for differentiated thyroid carcinoma in European studies. When heterogeneous studies were excluded, the analyses show that GD was a risk factor for recurrence/disease progression/persistence (P = 0.03, OR = 1.75, 95%C.I. = 1.04-2.95). The overall mortality rate was significantly higher in the Graves' disease group than in the non-Graves' disease group (P = 0.02, OR = 2.93, 95%C.I. = 1.17-7.37).

CONCLUSIONS

Graves' disease acts as a risk factor for the prognosis of differentiated thyroid carcinoma. The recurrence/disease progression/persistent rate may be affected by TSAbs in a specific location/race and with a genetic immunization background. However, the histotypes and subtypes may play an important role in mortality rate.

Enhanced ZnR/GPR39 Activity in Breast Cancer, an Alternative Trigger of Signaling Leading to Cell Growth

Acquired resistance to the estrogen receptor (ER) antagonist tamoxifen, is a major obstacle in treatment of breast cancer. Changes in Zn2+ accumulation and distribution are associated with tamoxifen-resistance and breast cancer progression. The Zn2+-sensing G-protein coupled receptor, ZnR/GPR39, triggers signaling leading to cell growth, but a role for this receptor in breast cancer in unknown. Using fluorescence imaging, we found Zn2+-dependent Ca2+ release, mediated by ZnR/GPR39 activity, in TAMR tamoxifen-resistant cells derived from MCF-7 cells, but not in ER-expressing MCF-7 or T47D cells. Furthermore, ZnR/GPR39 signaling was monitored in ER negative BT20, MDA-MB-453 and JIMT-1 cells. Expression of ZnR/GPR39 was increased in grade 3 human breast cancer biopsies compared to grade 2. Consistently, analysis of two breast cancer patient cohorts, GDS4057 and TCGA, indicated that in ER-negative tumors higher ZnR/GPR39 mRNA levels are associated with more aggressive tumors. Activation of ZnR/GPR39 in TAMR cells triggered MAPK, mTOR and PI3K signaling. Importantly, enhanced cell growth and invasiveness was observed in the ER negative breast cancer cells, TAMR, MDA-MB-453 and BT20 cells but not in the ER expressing MCF-7 cells. Thus, we suggest ZnR/GPR39 as a potential therapeutic target for combination treatment in breast cancer, particularly relevant in ER negative tumors.

The innate and adaptive infiltrating immune systems as targets for breast cancer immunotherapy

A cancer cell-centric view has long dominated the field of cancer biology. Research efforts have focussed on aberrant cancer cell signalling pathways and on changes to cancer cell DNA. Mounting evidence demonstrates that many cancer-associated cell types within the tumour stroma co-evolve and support tumour growth and development, greatly modifying cancer cell behaviour, facilitating invasion and metastasis and controlling dormancy and sensitivity to drug therapy. Thus, these stromal cells represent potential targets for cancer therapy. Among these cell types, immune cells have emerged as a promising target for therapy. The adaptive and the innate immune system play an important role in normal mammary development and breast cancer. The number of infiltrating adaptive immune system cells with tumour-rejecting capacity, primarily, T lymphocytes, is lower in breast cancer compared with other cancer types, but infiltration occurs in a large proportion of cases. There is strong evidence demonstrating the importance of the immunosuppressive role of the innate immune system during breast cancer progression. A consideration of components of both the innate and the adaptive immune system is essential for the design and development of immunotherapies in breast cancer. In this review, we focus on the importance of immunosuppressive myeloid-derived suppressor cells (MDSCs) as potential targets for breast cancer therapy.

Modeling the estrogen receptor to growth factor receptor signaling switch in human breast cancer cells

Breast cancer cells develop resistance to endocrine therapies by shifting between estrogen receptor (ER)-regulated and growth factor receptor (GFR)-regulated survival signaling pathways. To study this switch, we propose a mathematical model of crosstalk between these pathways. The model explains why MCF7 sub-clones transfected with HER2 or EGFR show three GFR-distribution patterns, and why the bimodal distribution pattern can be reversibly modulated by estrogen. The model illustrates how transient overexpression of ER activates GFR signaling and promotes estrogen-independent growth. Understanding this survival-signaling switch can help in the design of future therapies to overcome resistance in breast cancer.