Endocrine resistance in breast cancer

Interleukin-1 and Nuclear Factor Kappa B Signaling Promote Breast Cancer Progression and Treatment Resistance

While meant for wound healing and immunity in response to injury and infection, inflammatory signaling is usurped by cancerous tumors to promote disease progression, including treatment resistance. The interleukin-1 (IL-1) inflammatory cytokine family functions in wound healing and innate and adaptive immunity. Two major, closely related IL-1 family members, IL-1α and IL-1β, promote tumorigenic phenotypes and contribute to treatment resistance in cancer. IL-1 signaling converges on transactivation of the Nuclear Factor Kappa B (NF-κB) and Activator protein 1 (AP-1) transcription factors. NF-κB and AP-1 signaling are also activated by the inflammatory cytokine Tumor Necrosis Factor Alpha (TNFα) and microbe-sensing Toll-Like Receptors (TLRs). As reviewed elsewhere, IL-1, TNFα, and TLR can promote cancer progression through NF-κB or AP-1. In this review, we focus on what is known about the role of IL-1α and IL-1β in breast cancer (BCa) progression and therapeutic resistance, and state evidence for the role of NF-κB in mediating IL-1-induced BCa progression and therapeutic resistance. We will present evidence that IL-1 promotes BCa cell proliferation, BCa stem cell expansion, angiogenesis, and metastasis. IL-1 also regulates intracellular signaling and BCa cell hormone receptor expression in a manner that confers a growth advantage to the tumor cells and allows BCa cells to evade therapy. As such, the IL-1 receptor antagonist, anakinra, is in clinical trials to treat BCa and multiple other cancer types. This article presents a review of the literature from the 1990s to the present, outlining the evidence supporting a role for IL-1 and IL-1-NF-κB signaling in BCa progression.

The multifaceted role of lemur tyrosine kinase 3 in health and disease

In the last decade, LMTK3 (lemur tyrosine kinase 3) has emerged as an important player in breast cancer, contributing to the advancement of disease and the acquisition of resistance to therapy through a strikingly complex set of mechanisms. Although the knowledge of its physiological function is largely limited to receptor trafficking in neurons, there is mounting evidence that LMTK3 promotes oncogenesis in a wide variety of cancers. Recent studies have broadened our understanding of LMTK3 and demonstrated its importance in numerous signalling pathways, culminating in the identification of a potent and selective LMTK3 inhibitor. Here, we review the roles of LMTK3 in health and disease and discuss how this research may be used to develop novel therapeutics to advance cancer treatment.

Molecular modeling studies of benzothiophene-containing derivatives as promising selective estrogen receptor downregulators: a combination of 3D-QSAR, molecular docking and molecular dynamics simulations

Selective estrogen receptor downregulators (SERDs) for the treatment of positive breast cancer can act both as estrogen alpha receptor (ERα) antagonists and degraders. In this study, the optimal antagonist models (CoMFA-A, q² = 0.660, r² = 0.996; CoMSIA-A, q² = 0.728, r² = 0.992) and degrader models (CoMFA-D, q² = 0.850, r² = 0.996; CoMSIA-D, q² = 0.719, r² = 0.995) of a series of potent benzothiophene-containing SERDs were constructed to explore the three-dimensional quantitative structure-activity relationship. Internal and external validation indicated that all models exhibited good applicability, high predictive ability and robustness. Contour maps revealed the relationships between the essential structural features and antagonistic and degradation activities. Additionally, molecular docking, molecular dynamics and free energy calculation studies were further performed to investigate the detailed binding mode. Results indicated that several key residues, ARG394, GLU353, PHE404 and ILE424, were crucial for the stability of the ligand binding domain. The hydrophobic, electrostatic and Van der Waals interactions played significant effect on the binding affinity. Finally, ten novel compounds were designed based on above findings, where the predicted activity of compound D8 was equivalent to that of the compound LSZ102. 3D-QSAR, ADMET and bioavailability predictions indicated that all designed compounds with good predicted activity, good physicochemical and bioavailability could be potential candidates for SERDs. These results and combinations of computational methods provided guidance for the rational drug design of novel potential SERDs.Communicated by Ramaswamy H. Sarma.

Association of body mass and systemic immune-inflammation indices with endocrine therapy resistance in luminal breast cancers

Objective

To explore correlations between body mass index (BMI), preoperative systemic immune-inflammation index (SII) and endocrine therapy resistance, and evaluate BMI and SII as predictors of resistance, in patients with luminal breast cancer.

Methods

This retrospective study included patients with luminal breast cancer who underwent endocrine therapy at Hebei General Hospital. Relationships between BMI and SII subgroups, and clinicopathological parameters were analysed using χ²-tests. Disease-free survival was assessed using Log-rank statistics. Multivariate analysis of factors related to disease progression were analysed using Cox proportional hazards model.

Results

Out of 161 patients, those with normal BMI and low SII had significantly lower endocrine resistance rates versus those with high BMI and SII, and BMI was significantly positively correlated with SII. High BMI or SII was associated with significantly lower disease-free survival rates. Hazard ratios for disease progression risk were 6.036, 3.508 and 1.733, for SII, BMI and TNM stage, respectively.

Conclusion

In patients with luminal breast cancer, high BMI (>23 kg/m²) and SII (>518 × 10⁹/L) levels may predict high endocrine resistance rates. BMI, SII and TNM stage were independent prognostic factors for endocrine therapy resistance.

Fibronectin expression is upregulated by PI-3K/Akt activation in tamoxifen-resistant breast cancer cells

Fibronectin (FN) plays important roles in the EMT in a variety of cancer cell types. However, the mechanism by which FN expression is regulated in tamoxifen-resistant (TamR) breast cancer cells has not yet been fully elucidated. Aberrant FN expression was associated with poor prognosis in patients with luminal type A breast cancer. In addition, FN was upregulated in TamR cells. To investigate the mechanism by which FN expression is regulated, we assessed the levels of phosphorylated Akt, JNK, and STAT3 and found that they were all increased in TamR cells. Induction of FN expression was dampened by LY294002 or AKT IV in TamR cells. Furthermore, FN expression was increased by constitutively active (CA)-Akt overexpression in tamoxifen-sensitive MCF7 (TamS) cells and colony formation of TamR cells was blocked by AKT IV treatment. Taken together, these results demonstrate that FN expression is upregulated through the PI-3K/Akt pathway in tamoxifen-resistant breast cancer cells.

Microenvironment-Induced Non-sporadic Expression of the AXL and cKIT Receptors Are Related to Epithelial Plasticity and Drug Resistance

The existence of rare cancer cells that sporadically acquire drug-tolerance through epigenetic mechanisms is proposed as one mechanism that drives cancer therapy failure. Here we provide evidence that specific microenvironments impose non-sporadic expression of proteins related to epithelial plasticity and drug resistance. Microarrays of robotically printed combinatorial microenvironments of known composition were used to make cell-based functional associations between microenvironments, which were design-inspired by normal and tumor-burdened breast tissues, and cell phenotypes. We hypothesized that specific combinations of microenvironment constituents non-sporadically impose the induction of the AXL and cKIT receptor tyrosine kinase proteins, which are known to be involved in epithelial plasticity and drug-tolerance, in an isogenic human mammary epithelial cell (HMEC) malignant progression series. Dimension reduction analysis reveals type I collagen as a dominant feature, inducing expression of both markers in pre-stasis finite lifespan HMECs, and transformed non-malignant and malignant immortal cell lines. Basement membrane-associated matrix proteins, laminin-111 and type IV collagen, suppress AXL and cKIT expression in pre-stasis and non-malignant cells. However, AXL and cKIT are not suppressed by laminin-111 in malignant cells. General linear models identified key factors, osteopontin, IL-8, and type VIα3 collagen, which significantly upregulated AXL and cKIT, as well as a plasticity-related gene expression program that is often observed in stem cells and in epithelial-to-mesenchymal-transition. These factors are co-located with AXL-expressing cells in situ in normal and breast cancer tissues, and associated with resistance to paclitaxel. A greater diversity of microenvironments induced AXL and cKIT expression consistent with plasticity and drug-tolerant phenotypes in tumorigenic cells compared to normal or immortal cells, suggesting a reduced perception of microenvironment specificity in malignant cells. Microenvironment-imposed reprogramming could explain why resistant cells are seemingly persistent and rapidly adaptable to multiple classes of drugs. These results support the notion that specific microenvironments drive drug-tolerant cellular phenotypes and suggest a novel interventional avenue for preventing acquired therapy resistance.

Breast cancer genomics and immuno-oncological markers to guide immune therapies

There is an increasing awareness of the importance of tumor - immune cell interactions to the evolution and therapy responses of breast cancer (BC). Not surprisingly, numerous studies are currently assessing the clinical value of immune modulation for BC patients. However, till now durable clinical responses are only rarely observed. It is important to realize that BC is a heterogeneous disease comprising several histological and molecular subtypes, which cannot be expected to be equally immunogenic and therefore not equally sensitive to single immune therapies. Here we review the characteristics of infiltrating leukocytes in healthy and malignant breast tissue, the prognostic and predictive values of immune cell subsets across different BC subtypes and the various existing immune evasive mechanisms. Furthermore, we describe the presence of certain groups of antigens as putative targets for treatment, evaluate the outcomes of current clinical immunotherapy trials, and finally, we propose a strategy to better implement immuno-oncological markers to guide future immune therapies in BC.

Treatment for the endocrine resistant breast cancer: Current options and future perspectives

Endocrine resistance remains a challenge and an unmet need for managing hormone receptor-positive breast cancer. The mechanisms of endocrine resistance are multifaceted and are likely to evolve over time following various single or combination therapies. The purpose of this review article is to provide general understanding of molecular basis of endocrine resistance of breast cancer and to offer comprehensive review on current treatment options and potential new treatment strategies for endocrine resistant breast cancers. Last but not the least, we discuss current challenges and future directions for management of endocrine resistant breast cancers.

Estrogen receptor α (ERα) status evaluation using RNAscope in situ hybridization: a reliable and complementary method for IHC in breast cancer tissues

Estrogen receptor α (ERα) plays a significant role in the development of breast cancer and has been used clinically as an endocrine therapeutic target. Currently, clinical laboratories use immunohistochemistry (IHC) to determine the ERα status of patients in order to distinguish those who would benefit from endocrine therapy. This method is highly subjective, requires a large amount of tumor tissue, and may generate false-negative results. To improve the detection of ERα, we used a new RNA in situ hybridization technique (RNAscope) and compared its use with IHC in 72 breast cancer tissues (47 ERα positive and 25 ERα negative). Then we evaluated ERα mRNA by RT-qPCR with RNAscope. An unobvious difference was found between reverse-transcription quantitative polymerase chain reaction (RT-qPCR) and IHC, but a positive correlation was found between RNAscope and IHC. In addition, breast cancer is a highly heterogeneous cancer, and RNAscope could easily reveal the heterogeneity in breast cancer. Moreover, we found that some ERα IHC-based negative and RNAscope-based positive test results were detected as positive after testing with IHC again. Our findings suggest that RNAscope may be a complementary method for improving the detection of patient ERα status and has potential clinical utility.

DMXL2 drives epithelial to mesenchymal transition in hormonal therapy resistant breast cancer through Notch hyper-activation

The acquisition of endocrine therapy resistance in estrogen receptor α (ERα) breast cancer patients represents a major clinical problem. Notch signalling has been extensively linked to breast cancer especially in patients who fail to respond to endocrine therapy. Following activation, Notch intracellular domain is released and enters the nucleus where activates transcription of target genes. The numerous steps that cascade after activation of the receptor complicate using Notch as biomarker. Hence, this warrants the development of reliable indicators of Notch activity. DMXL2 is a novel regulator of Notch signalling not yet investigated in breast cancer. Here, we demonstrate that DMXL2 is overexpressed in a subset of endocrine therapy resistant breast cancer cell lines where it promotes epithelial to mesenchymal transition through hyper-activation of Notch signalling via V-ATPase dependent acidification. Following DMXL2 depletion or treatment with Bafilomycin A1, both EMT targets and Notch signalling pathway significantly decrease. We show for the first time that DMXL2 protein levels are significantly increased in ERα positive breast cancer patients that progress after endocrine therapy. Finally, we demonstrate that DMXL2 is a transmembrane protein with a potential extra-cellular domain. These findings identify DMXL2 as a novel, functional biomarker for ERα positive breast cancer.

Overcoming Resistance to Endocrine Therapy in Breast Cancer: New Approaches to a Nagging Problem

In the majority of women, breast cancer progresses through increased transcriptional activity due to over-expressed oestrogen receptors (ER). Therapeutic strategies include: (i) reduction of circulating ovarian oestrogens or of peripherally produced oestrogen (in postmenopausal women) with aromatase inhibitors and (ii) application of selective ER modulators for receptor blockade. The success of these interventions is limited by the variable but persistent onset of acquired resistance and by an intrinsic refractiveness which manifests despite adequate levels of ER in about 50% of patients with advanced metastatic disease. Loss of functional ER leads to endocrine insensitivity, loss of cellular adhesion and polarity, and increased migratory potential due to trans-differentiation of the epithelial cancer cells into a mesenchymal-like phenotype (epithelial-mesenchymal transition; EMT). Multiple mechanisms contributing to therapeutic failure have been proposed: (i) loss or modification of ER expression including epigenetic mechanisms, (ii) agonistic actions of selective ER modulators that may be enhanced through an increased expression of co-activators, (iii) attenuation of the tamoxifen metabolism through expression of genetic variants of P450 cytochromes which leads to more or less active metabolites and (iv) increased growth factor signalling particularly through epidermal growth factor receptor activation of pathways involving keratinocyte growth factor, platelet-derived growth factor, and nuclear factor x03BA;B. In addition, the small non-coding microRNAs, recently recognized as critical gene regulators, exhibit differential expression in tamoxifen-sensitive versus resistant cell lines. Several studies suggest the potential of using these either as targets or as therapeutic agents to modulate EMT regulators as a means of reversing the aggressive metastatic phenotype by reversal of the EMT, with the added benefit of re-sensitization to anti-oestrogens.