A review of the biological and clinical characteristics of luminal-like oestrogen receptor-positive breast cancer

Glucocorticoid receptor-mediated oncogenic activity is dependent on breast cancer subtype

Breast cancer incidence has been steadily rising and is the leading cause of cancer death in women due to its high metastatic potential. Individual breast cancer subtypes are classified by both cell type of origin and receptor expression, namely estrogen, progesterone and human epidermal growth factor receptors (ER, PR and HER2). Recently, the importance and context-dependent role of glucocorticoid receptor (GR) expression in the natural history and prognosis of breast cancer subtypes have been uncovered. In ER-positive breast cancer, GR expression is associated with a better prognosis as a result of ER-GR crosstalk. GR appears to modulate ER-mediated gene expression resulting in decreased tumor cell proliferation and a more indolent cancer phenotype. In ER-negative breast cancer, including GR-positive triple-negative breast cancer (TNBC), GR expression enhances migration, chemotherapy resistance and cell survival. In invasive lobular carcinoma, GR function is relatively understudied, and more work is required to determine whether lobular subtypes behave similarly to their invasive ductal carcinoma counterparts. Importantly, understanding GR signaling in individual breast cancer subtypes has potential clinical implications because of the recent development of highly selective GR non-steroidal ligands, which represent a therapeutic approach for modulating GR activity systemically.

A Clinicopathological Analysis of Molecular Subtypes of Breast Cancer using Immunohistochemical Surrogates: A 6-Year Institutional Experience from a Tertiary Cancer Center in North India

Puneet Kaur SomalObjective  Classification of breast cancer into different molecular subtypes has important prognostic and therapeutic implications. The immunohistochemistry surrogate classification has been advocated for this purpose. The primary objective of the present study was to assess the prevalence of the different molecular subtypes of invasive breast carcinoma and study the clinicopathological parameters in a tertiary care cancer center in rural North India. Materials and Methods  All female patients diagnosed with invasive breast cancer and registered between January 1, 2015, and December 31, 2020, were included. Patients with bilateral cancer, missing information on HER2/ER/PR receptor status, absence of reflex FISH testing after an equivocal score on Her 2 IHC were excluded. The tumors were classified into different molecular subtypes based on IHC expression as follows-luminal A-like (ER- and PR-positive, Her2-negative, Ki67 < 20%), luminal B-like Her2-negative (ER-positive, Her2-negative and any one of the following Ki67% ≥ 20% or PR-negative/low, luminal B-like Her2-positive (ER- and HER2-positive, any Ki67, any PR), Her2-positive (ER- and PR-negative, Her2-positive) and TNBC (ER, PR, Her2-negative). Chi square test was used to compare the clinicopathological parameters between these subtypes. Results  A total of 1,625 cases were included. Luminal B-like subtype was the most common (41.72%). The proportion of each subtype was luminal A (15.69%), luminal B Her2-negative (23.93%), luminal B Her2-positive (17.78%), Her2-positive (15.26%), TNBC (27.32%). Majority of the tumors were Grade 3 (75.81%). Nodal metastases were present in 59%. On subanalysis of the luminal type tumors without Her2 expression (luminal A-like and luminal B-like (Her2-negative), luminal A-like tumors presented significantly with a lower grade ( p  < 0.001) and more frequent node-negative disease in comparison to luminal B-like (Her2-negative) tumors. In comparison to other subtypes, TNBC tumors were more frequently seen in the premenopausal age group ( p  < 0.001) and presented with node-negative disease ( p  < 0.001). Conclusion  This is one of the largest studies that enumerates the prevalence of various molecular subtypes of breast cancer in North India. Luminal B-like tumors were the most common followed by TNBC. TNBC tumors presented more commonly in premenopausal age group and with node negative disease in comparison to other subtypes.

Side Effects and Its Management in Adjuvant Endocrine Therapy for Breast Cancer: A Matter of Communication and Counseling

Objective

Women with a newly diagnosed hormone receptor-positive breast cancer are offered adjuvant endocrine therapy (AET). Although the treatment reduces the risk of relapse and death not all women are adherent to it. Many factors, including the therapy's menopausal side effects, can adversely affect adherence to the treatment. This study explores the extent to which women treated with AET perceived that health care providers addressed their side effects.

Methods

Ten focus groups were set up, containing between four to nine women. In total, 58 women participated in the study-45 from the Stockholm metropolitan region and 13 from the scarcely populated Norrbotten region. The interviews were analyzed using qualitative content analysis with an inductive approach.

Results

The women were usually satisfied with the care they received from the health care providers. However, their experiences were more complex when it came to their satisfaction with the care in terms of the menopausal side effects of therapy, sexuality in particular. The participants reported that their healthcare providers rarely asked about sex life-related side effects of the treatment.

Conclusions

Health care providers need to communicate and consult about issues related to their patients' sex lives following their breast cancer diagnosis and during their treatment.

Analysis of breast cancer subtypes and their correlations with receptors and ultrasound

The study aim was to evaluate the ultrasound (US) signs of the mammary lesions classified in the Breast Imaging-Reporting and Data System (BI-RADS) score category 3, 4, and 5, corresponding to US BI-RADS. It also followed the correlation between US changes of lesions suggestive for malignancy with the histopathological results and evaluated the proper management of those lesions. There were correlations of breast cancer (BC) subtypes with the receptors [estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2)], and Ki67 index, and the signs of conventional ultrasonography and US elastography. We selected 108 female patients examined with US, mammography and fine-needle biopsy who presented suspicions for malignancy lesions. Following the immunohistochemical analysis, they were classified in one of the BC subtypes. According to chi-squared analysis of molecular cancer subtypes correlation to receptors and Ki67 index, we found significant associations between both luminal A and luminal B HER2-negative subtypes and hormone receptors (ER, PR). These have an inverse relationship with Ki67 index elevated values; luminal B HER2-positive subtype has a direct association with HER2 presence; HER2-enriched subtype was statistically significant associated to HER2 presence and elevated Ki67 index values but had an inverse relationship to hormone receptors (ER, PR); triple-negative subtype was strongly associated to Ki67 index values and inversely correlated to ER and PR. We found luminal A subtype as being the most common and luminal B HER2-positive subtype as having the fewer cases.

New Advances in Molecular Breast Cancer Pathology

Breast cancer (BC) comprises a diverse spectrum of diseases featuring distinct presentation, morphological, biological, and clinical phenotypes. BC behaviour and response to therapy also vary widely. Current evidence indicates that traditional prognostic and predictive classification systems are insufficient to reflect the biological and clinical heterogeneity of BC. Advancements in high-throughput molecular techniques and bioinformatics have contributed to the improved understanding of BC biology, refinement of molecular taxonomies and the development of novel prognostic and predictive molecular assays. Molecular testing has also become increasingly important in the diagnosis and treatment of BC in the era of precision medicine. Despite the enormous amount of research work to develop and refine BC molecular prognostic and predictive assays, it is still in evolution and proper incorporation of these molecular tests into clinical practice to guide patient's management remains a challenge. With the increasing use of more sophisticated high throughput molecular techniques, large amounts of data will continue to emerge, which could potentially lead to identification of novel therapeutic targets and allow more precise classification systems that can accurately predict outcome and response to therapy. In this review, we provide an update on the molecular classification of BC and molecular prognostic assays. Companion diagnostics, contribution of massive parallel sequencing and the use of liquid biopsy are also highlighted.

Gene expression and DNA methylation analyses suggest that immune process-related ADCY6 is a prognostic factor of luminal-like breast cancer

Breast cancer is a malignant tumor that seriously threatens women's health, and luminal-like cancer subtypes account for the majority of the cases. The purpose of this study was to investigate the relationships among DNA methylation, gene expression profile, and the tumor-immune microenvironment of luminal-like breast cancer, and to identify the potential key genes that regulate immune cell infiltration in luminal-like breast cancer. The ESTIMATE algorithm was applied to calculate immune scores and stromal scores of patients with breast cancer. Kaplan-Meier curves were generated for survival analysis. The clusterProfile package was used for Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis. The protein-protein interaction (PPI) network was constructed using the STRING database and Cytoscape software. Correlations between ADCY6 expression and immune cell infiltration-related pathways were analyzed by gene set variation analysis. R software was used for the statistical analysis and figure generation. Disease-free survival was higher in the immune score-high group than it was in the immune score-low group, while the stromal score had no correlation with prognosis. There were 515 genes that differed in both gene expression and DNA methylation levels, and these genes were mainly enriched in immune process-related pathways. ADCY6 was enriched in module A of the PPI network. Patients with downregulation and hypermethylation of ADCY6 associated with a better prognosis. ADCY6 expression was negatively correlated with the activation of immune process-related signaling pathways, immune checkpoint receptors, and ligands, except for CLEC4G. DNA methylation was found to be involved in the regulation of the key cellular pathways of luminal-like breast cancer immune cell infiltration. Additionally, ADCY6 was identified as a prognostic factor involved in the DNA methylation-regulated immune processes in luminal-like breast cancer.

Rat models of 17β-estradiol-induced mammary cancer reveal novel insights into breast cancer etiology and prevention

Numerous laboratory and epidemiologic studies strongly implicate endogenous and exogenous estrogens in the etiology of breast cancer. Data summarized herein suggest that the ACI rat model of 17β-estradiol (E2)-induced mammary cancer is unique among rodent models in the extent to which it faithfully reflects the etiology and biology of luminal types of breast cancer, which together constitute ~70% of all breast cancers. E2 drives cancer development in this model through mechanisms that are largely dependent upon estrogen receptors and require progesterone and its receptors. Moreover, mammary cancer development appears to be associated with generation of oxidative stress and can be modified by multiple dietary factors, several of which may attenuate the actions of reactive oxygen species. Studies of susceptible ACI rats and resistant COP or BN rats provide novel insights into the genetic bases of susceptibility and the biological processes regulated by genetic determinants of susceptibility. This review summarizes research progress resulting from use of these physiologically relevant rat models to advance understanding of breast cancer etiology and prevention.

Conditional expression of Ki-RasG12V in the mammary epithelium of transgenic mice induces estrogen receptor alpha (ERα)-positive adenocarcinoma

Appropriate 'in vivo' models are crucial for studying breast cancer biology and evaluating the efficacy of therapeutic agents. Thus we engineered a novel transgenic mouse line expressing the human Ki-Ras bearing an activating mutation (Ki-Ras^(G12V)) selectively in the mammary epithelium after lactation. These mice develop invasive ductal adenocarcinomas with 100% incidence within 3-9 months after Ki-Ras^(G12V) induction. Immunophenotyping revealed that the mammary tumors express luminal markers, are positive for estrogen and progesterone receptors, negative for HER2 and have a low proliferation index. Moreover, cell lines derived from such tumors are estrogen-responsive and, when transplanted into nude mice, form tumors that respond to the antiestrogen ICI 182780. In conclusion, the mammary tumors of these transgenic mice and the derived cell lines exhibit key features of the major form of human breast cancer, that is, luminal A subtype and thus have a high potential for breast cancer research and treatment.

Overview of Genetically Engineered Mouse Models of Breast Cancer Used in Translational Biology and Drug Development

Breast cancer is a heterogeneous condition with no single standard of treatment and no definitive method for determining whether a tumor will respond to therapy. The development of murine models that faithfully mimic specific human breast cancer subtypes is critical for the development of patient-specific treatments. While the artificial nature of traditional in vivo xenograft models used to characterize novel anticancer treatments has limited clinical predictive value, the development of genetically engineered mouse models (GEMMs) makes it possible to study the therapeutic responses in an intact microenvironment. GEMMs have proven to be an experimentally tractable platform for evaluating the efficacy of novel therapeutic combinations and for defining the mechanisms of acquired resistance. Described in this overview are several of the more popular breast cancer GEMMs, including details on their value in elucidating the molecular mechanisms of this disorder.

Biological subtypes of breast cancer: Prognostic and therapeutic implications

Breast cancer is a heterogeneous complex of diseases, a spectrum of many subtypes with distinct biological features that lead to differences in response patterns to various treatment modalities and clinical outcomes. Traditional classification systems regarding biological characteristics may have limitations for patient-tailored treatment strategies. Tumors with similar clinical and pathological presentations may have different behaviors. Analyses of breast cancer with new molecular techniques now hold promise for the development of more accurate tests for the prediction of recurrence. Gene signatures have been developed as predictors of response to therapy and protein gene products that have direct roles in driving the biology and clinical behavior of cancer cells are potential targets for the development of novel therapeutics. The present review summarizes current knowledge in breast cancer molecular biology, focusing on novel prognostic and predictive factors.

Genetically engineered ERα-positive breast cancer mouse models

The majority of human breast cancers are estrogen receptor-positive (ER+), but this has proven challenging to model in genetically engineered mice. This review summarizes information on 21 mouse models that develop ER+ mammary cancer. Where available, information on cancer pathology and gene expression profiles is referenced to assist in understanding which histological subtype of ER+ human cancer each model might represent. ESR1, CCDN1, prolactin, TGFα, AIB1, ESPL1, and WNT1 overexpression, PIK3CA gain of function, as well as loss of P53 (Trp53) or STAT1 are associated with ER+ mammary cancer. Treatment with the PPARγ agonist efatutazone in a mouse with Brca1 and p53 deficiency and 7,12-dimethylbenz(a)anthracene exposure in combination with an activated myristoylated form of AKT1 also induce ER+ mammary cancer. A spontaneous mutant in nude mice that develops metastatic ER+ mammary cancer is included. Age of cancer development ranges from 3 to 26 months and the percentage of cancers that are ER+ vary from 21 to 100%. Not all models are characterized as to their estrogen dependency and/or response to anti-hormonal therapy. Strain backgrounds include C57Bl/6, FVB, BALB/c, 129S6/SvEv, CB6F1, and NIH nude. Most models have only been studied on one strain background. In summary, while a range of models are available for studies of pathogenesis and therapy of ER+ breast cancers, many could benefit from further characterization, and opportunity for development of new models remains.