Multipotent luminal mammary cancer stem cells model tumor heterogeneity

Mechanism of action of genistein on breast cancer and differential effects of different age stages

CONTEXT

Genistein, a soy-derived isoflavone, exhibits structural similarities with 17β-estradiol and demonstrates antioxidant, anti-inflammatory, and estrogenic properties. Despite its low bioavailability limiting its clinical application, it shows potential for breast cancer prevention and treatment.

OBJECTIVE

This review aims to summarize the pharmacological effects and molecular mechanisms of genistein in breast cancer, focusing on its therapeutic potential, strategies to overcome bioavailability limitations, and its role in personalized medicine. Differential impacts among population subgroups are also discussed.

METHODS

A systematic review was conducted using PubMed, ScienceDirect, and Google Scholar databases. Studies were selected based on their focus on genistein's mechanisms of action, strategies to enhance its bioavailability, and interactions with other therapies.

RESULTS

Genistein exerted anticancer effects by modulating estrogen receptor β (ERβ), inhibiting angiogenesis, arresting the cell cycle, and inducing apoptosis. Its antioxidant properties help mitigate tumor-associated oxidative stress. Bioavailability enhancement strategies, such as nanoparticle and lipid-based formulations, show promise. Age-dependent effects were evident, with distinct responses observed in prepubertal, menopausal, and postmenopausal populations, underscoring its potential for personalized therapies. Furthermore, genistein influences epigenetic modifications, including DNA methylation and miRNA expression, bolstering its anticancer efficacy.

CONCLUSION

Genistein is a promising candidate for breast cancer therapy, particularly for personalized treatment. Strategies to enhance bioavailability and further clinical research are essential to optimize its therapeutic potential and evaluate its efficacy in combination therapies.

Impact of Psychological Stress and Spontaneous Tumour Regression on the Hippocampal Proteome in a Mouse Model of Breast Cancer

Cognitive impairment is common in people diagnosed with breast cancer, but the molecular mechanisms that underlie maladaptive changes in the brain are unknown. The psychological stress of a cancer diagnosis is certainly a contributing factor. Here, we investigated alterations in the hippocampal proteome in response to both cancer and psychological stress using label-free quantitative mass spectrometry techniques. An orthotopic syngeneic model of triple-negative breast cancer (TNBC) was established by injecting Py230 cells into the mammary fat pads of female C57Bl/6 mice. Half of the mice were subjected to a daily restraint stress paradigm. Mice that experienced both cancer and restraint stress lost weight and displayed larger tumours compared to non-stressed mice. Their urinary corticosterone levels were also elevated, as measured by enzyme-linked immunosorbent assay. Non-stressed tumour-bearing mice displayed higher levels of TNFα in the prefrontal cortex (PFC) compared to stressed mice with cancer. Flow cytometry results suggested that the CD4+/CD8+ T cell ratios were also raised in non-stressed tumour-bearing mice compared to both controls and stressed mice with TNBC. Bioinformatic analysis of hippocampal proteomes indicated that cancer alone causes reduced mitochondrial respiration and ATP synthesis, as well as impaired glutamate recycling and synaptic plasticity. Moreover, daily stress in TNBC mice caused further mitochondrial dysfunction, increased oxidative phosphorylation, and altered lipid metabolism. Importantly, over half of the mammary tumours that initially developed spontaneously regressed after 7-9 weeks in these young immunocompetent mice. Tumour regression inhibited TNFα increases in the PFC. However, the hippocampal proteomes of tumour-bearing mice were largely similar to mice in which tumours regressed, suggesting that spontaneous regression of breast cancer confers lasting physiological dysregulations that impact hippocampal protein expression. This study in mice may help to identify molecular mechanisms responsible for long-term memory impairments in cancer survivors and reveal novel drug targets for cancer-related cognitive impairment.

Mcam stabilizes a luminal progenitor-like breast cancer cell state via Ck2 control and Src/Akt/Stat3 attenuation

Cell state control is crucial for normal tissue development and cancer cell mimicry of stem/progenitor states, contributing to tumor heterogeneity, therapy resistance, and progression. Here, we demonstrate that the cell surface glycoprotein Mcam maintains the tumorigenic luminal progenitor (LP)-like epithelial cell state, leading to Basal-like mammary cancers. In the Py230 mouse mammary carcinoma model, Mcam knockdown (KD) destabilized the LP state by deregulating the Ck2/Stat3 axis, causing a switch to alveolar and basal states, loss of an estrogen-sensing subpopulation, and resistance to tamoxifen-an effect reversed by Ck2 and Stat3 inhibitors. In vivo, Mcam KD blocked generation of Basal-like tumors and Sox10+Krt14+ cells. In human tumors, MCAM loss was largely exclusive of the Basal-like subtype, linked instead to proliferative Luminal subtypes, including often endocrine-resistant Luminal B cancers. This study has implications for developing therapies targeting MCAM, CK2, and STAT3 and their likely effective contexts.

Concise review: breast cancer stems cells and their role in metastases

Background

Breast cancer stem cells (BCSCs) have been suggested to be responsible for the development of Breast cancer (BC). The aim of this study was to evaluate BCSCs and the target organs microenvironment immunophenotyping markers in common BC metastases, and therapeutic targets regarding to the mentioned criteria.

Material and methods

This narrative review involved searching international databases; PubMed, Google Scholar using predetermined keywords including breast cancer, breast cancer stem cells, breast cancer metastases, immunophenotyping, immunohistochemistry and metastases. The search results were assessed based on the title, abstract, and full text of the articles, and relevant findings were included in the review.

Results

BCSCs express high amounts of aldehyde dehydrogenase 1 (ALDH1), Ganglioside 2 (GD2), CD44 and CD133 but are negative for CD24 marker. CXCR4 and OPN have high expression in the cells and may contribute in BC metastasis to the bone. Nestin, CK5, prominin-1 (CD133) markers in BCSCs have been reported to correlate with brain metastasis. High expression of CD44 in BCSCs and CXCL12 expression in the liver microenvironment may contribute to BC metastasis to the liver. Aberrantly expressed vascular cell adhesion molecule-1 (VCAM-1) that binds to collagen and elastin fibers on pulmonary parenchyma, and CXCR4 of BCSCs and CXCL12 in lung microenvironment may promote the cells homing and metastasis to lung.

Conclusion

As in various types of BC metastases different markers that expressed by the cells and target organ microenvironment are responsible, BCSCs immunophenotyping can be used as target markers to predict the disease prognosis and treatment.

Epigenetic regulation of breast cancer metastasis

Breast cancer is the most frequently diagnosed malignancy and the second leading cause of cancer-related mortality among women worldwide. Recurrent metastasis is associated with poor patient outcomes and poses a significant challenge in breast cancer therapies. Cancer cells adapting to a new tissue microenvironment is the key event in distant metastasis development, where the disseminating tumor cells are likely to acquire genetic and epigenetic alterations during the process of metastatic colonization. Despite several decades of research in this field, the exact mechanisms governing metastasis are not fully understood. However, emerging body of evidence indicates that in addition to genetic changes, epigenetic reprogramming of cancer cells and the metastatic niche are paramount toward successful metastasis. Here, we review and discuss the latest knowledge about the salient attributes of metastasis and epigenetic regulation in breast cancer and crucial research domains that need further investigation.

Mcam stabilizes luminal progenitor breast cancer phenotypes via Ck2 control and Src/Akt/Stat3 attenuation

Breast cancers are categorized into subtypes with distinctive therapeutic vulnerabilities and prognoses based on their expression of clinically targetable receptors and gene expression patterns mimicking different cell types of the normal gland. Here, we tested the role of Mcam in breast cancer cell state control and tumorigenicity in a luminal progenitor-like murine tumor cell line (Py230) that exhibits lineage and tumor subtype plasticity. Mcam knockdown Py230 cells show augmented Stat3 and Pi3K/Akt activation associated with a lineage state switch away from a hormone-sensing/luminal progenitor state toward alveolar and basal cell related phenotypes that were refractory to growth inhibition by the anti-estrogen therapeutic, tamoxifen. Inhibition of Stat3, or the upstream activator Ck2, reversed these cell state changes. Mcam binds Ck2 and acts as a regulator of Ck2 substrate utilization across multiple mammary tumor cell lines. In Py230 cells this activity manifests as increased mesenchymal morphology, migration, and Src/Fak/Mapk/Paxillin adhesion complex signaling in vitro, in contrast to Mcam's reported roles in promoting mesenchymal phenotypes. In vivo, Mcam knockdown reduced tumor growth and take rate and inhibited cell state transition to Sox10+/neural crest like cells previously been associated with tumor aggressiveness. This contrasts with human luminal breast cancers where MCAM copy number loss is highly coupled to Cyclin D amplification, increased proliferation, and the more aggressive Luminal B subtype. Together these data indicate a critical role for Mcam and its regulation of Ck2 in control of breast cancer cell state plasticity with implications for progression, evasion of targeted therapies and combination therapy design.

The application of nanoparticles in theranostic systems targeting breast cancer stem cells: current progress and future challenges

Breast cancer (BC) is one of the diseases with the highest female mortality rates in the world and is closely related to breast cancer stem cells (BCSCs). Conventional breast cancer chemotherapy drugs target noncancer stem cells (non-CSCs), while cancer stem cells (CSCs) can still survive, which is an important reason for breast cancer drug resistance and local recurrence or distant metastasis. How to eradicate BCSCs while killing BCs is the key factor to improve the effect, and it is also an important scientific problem to be solved urgently. Therefore, targeted BCSC therapy has become a research hotspot. Interestingly, the emergence of nanotechnology provides a new idea for targeting BCSCs. This study summarizes the current application status of nanomaterials in targeting BCSCs, and attempts to construct a new type of lipid nanoparticle (LNP) that can target BCSCs through mRNA, providing a new idea for the treatment of BC.

Isogenic Mammary Models of Intraductal Carcinoma Reveal Progression to Invasiveness in the Absence of a Non-Obligatory In Situ Stage

In breast cancer, progression to invasive ductal carcinoma (IDC) involves interactions between immune, myoepithelial, and tumor cells. Development of IDC can proceed through ductal carcinoma in situ (DCIS), a non-obligate, non-invasive stage, or IDC can develop without evidence of DCIS and these cases associate with poorer prognosis. Tractable, immune-competent mouse models are needed to help delineate distinct mechanisms of local tumor cell invasion and prognostic implications. To address these gaps, we delivered murine mammary carcinoma cell lines directly into the main mammary lactiferous duct of immune-competent mice. Using two strains of immune-competent mice (BALB/c, C57BL/6), one immune-compromised (severe combined immunodeficiency; SCID) C57BL/6 strain, and six different murine mammary cancer cell lines (D2.OR, D2A1, 4T1, EMT6, EO771, Py230), we found early loss of ductal myoepithelial cell differentiation markers p63, α-smooth muscle actin, and calponin, and rapid formation of IDC in the absence of DCIS. Rapid IDC formation also occurred in the absence of adaptive immunity. Combined, these studies demonstrate that loss of myoepithelial barrier function does not require an intact immune system, and suggest that these isogenic murine models may prove a useful tool to study IDC in the absence of a non-obligatory DCIS stage-an under-investigated subset of poor prognostic human breast cancer.

A Tumor Microenvironment-Driven Network Regulated by STAT3 and p65 Negatively Controls the Enrichment of Cancer Stem Cells in Human HR+/HER2- Breast Cancer

Hormone receptor-positive and HER2-negative (HR+/HER2-; luminal A) tumors are prevalent in breast cancer. Our past studies demonstrated that "TME Stimulation" (estrogen + TNFα + EGF, representing three arms of the tumor microenvironment, TME) has enriched metastasis-forming cancer stem cells (CSCs) in HR+/HER2- human breast cancer cells. Here, following information obtained by RNAseq analyses of TME-stimulated CSCs and Non-CSCs, we found that TME Stimulation has induced the activation of S727-STAT3, Y705-STAT3, STAT1 and p65. Upon TME Stimulation, stattic (STAT3 inhibitor) usage demonstrated that Y705-STAT3 activation negatively controlled CSC enrichment and epithelial-to-mesenchymal transition (EMT) traits, while inducing CXCL8 (IL-8) and PD-L1 expression. However, STAT3 knock-down (siSTAT3) had no effect on these functions; in terms of CSC enrichment, p65 had down-regulatory roles that compensated for the loss of an entire STAT3 protein. Y705-STAT3 and p65 acted additively in reducing CSC enrichment, and Y705A-STAT3 variant + sip65 has enriched chemo-resistant CSCs. Clinical data analyses revealed an inverse correlation between Y705-STAT3 + p65 phosphorylation and CSC signature in luminal A patients, and connection to improved disease course. Overall, we find regulatory roles for Y705-STAT3 and p65 in TME-stimulated HR+/HER2- tumors, with the ability to limit CSC enrichment. These findings raise concerns about using inhibitors of STAT3 and p65 as therapeutic strategies in the clinic.

One cisplatin dose provides durable stimulation of anti-tumor immunity and alleviates anti-PD-1 resistance in an intraductal model for triple-negative breast cancer

Aggressive triple-negative breast cancer (TNBC) is classically treated with chemotherapy. Besides direct tumor cell killing, some chemotherapeutics such as cisplatin provide additional disease reduction through stimulation of anti-tumor immunity. The cisplatin-induced immunomodulation in TNBC was here investigated in-depth using immunocompetent intraductal mouse models. Upon primary tumor transition to invasive carcinoma, cisplatin was injected systemically and significantly reduced tumor progression. Flow cytometric immunophenotyping was corroborated by immunohistochemical analyses and revealed both differential immune cell compositions and positivity for their programmed death (PD)-1 and PD-ligand (L)1 markers across body compartments, including the primary tumor, axillary lymph nodes and spleen. As key findings, a significant decrease in immunosuppressive and a concomitant increase in anti-tumor lymphocytic cell numbers were observed in the axillary lymph nodes and spleen, highlighting their importance in cisplatin-stimulated anti-tumor immunity. These immunomodulatory effects were already established following the first cisplatin dose, indicating that early cisplatin-mediated events may determine (immuno)therapeutic outcome. Furthermore, a single cisplatin dose sufficed to alleviate anti-PD-1 resistance in a 4T1-based model, providing add-on disease reduction without toxic side effects as seen upon multiple cisplatin dosing. Overall, these results highlight cisplatin as immunotherapeutic ally in TNBC, providing durable immunostimulation, even after a single dose.

Comparative Analysis of microRNAs that Stratify in vitro Mammary stem and Progenitor Activity Reveals Functionality of Human miR-92b-3p

Mammary stem/progenitor cells are fundamental for mammary gland development and function. However, much remains to be elucidated regarding their function in mammals beyond the traditionally studied rodents, human, and to a lesser extent, ruminants. Due to the growing appreciation for microRNAs (miRNAs) as regulators of stem cells and their progenitors, we compared miRNA expression in mammary stem/progenitor cells from mammals with varying mammary stem/progenitor activity in vitro, in order to identify miRNA candidates that regulate stem/progenitor self-renewal and function. Mammosphere-derived epithelial cells (MDECs), which are primary cell lines enriched in mammary stem and progenitor cells, were generated from six mammalian species (i.e., cow, human, pig, horse, dog, and rat) and small RNA sequencing was performed. We identified 9 miRNAs that were significantly differentially expressed in MDEC cultures with a low versus high mammary stem/progenitor activity. miR-92b-3p was selected for functional follow-up studies, as this miRNA is understudied in primary mammary cells but has well-described gene targets that are known to regulate mammary stem/progenitor activity. Altering the expression of miR-92b-3p in MDECs from species with low stem/progenitor activity (human and cow) and those with high stem/progenitor activity (dog and rat) via inhibition and overexpression, respectively, resulted in significantly decreased mammosphere formation of human MDECs, but showed no significant effects in cow, dog, or rat MDECs. This study is the first to perform small RNA sequencing in MDECs from various mammals and highlights that conserved miRNAs can have different functions in mammary stem/progenitor cells across species.

Targeting Breast Cancer Stem Cells Using Naturally Occurring Phytoestrogens

Breast cancer therapies have made significant strides in improving survival for patients over the past decades. However, recurrence and drug resistance continue to challenge long-term recurrence-free and overall survival rates. Mounting evidence supports the cancer stem cell model in which the existence of a small population of breast cancer stem cells (BCSCs) within the tumor enables these cells to evade conventional therapies and repopulate the tumor, giving rise to more aggressive, recurrent tumors. Thus, successful breast cancer therapy would need to target these BCSCs, as well the tumor bulk cells. Since the Women’s Health Initiative study reported an increased risk of breast cancer with the use of conventional hormone replacement therapy in postmenopausal women, many have turned their attention to phytoestrogens as a natural alternative. Phytoestrogens are plant compounds that share structural similarities with human estrogens and can bind to the estrogen receptors to alter the endocrine responses. Recent studies have found that phytoestrogens can also target BCSCs and have the potential to complement conventional therapy eradicating BCSCs. This review summarized the latest findings of different phytoestrogens and their effect on BCSCs, along with their mechanisms of action, including selective estrogen receptor binding and inhibition of molecular pathways used by BCSCs. The latest results of phytoestrogens in clinical trials are also discussed to further evaluate the use of phytoestrogen in the treatment and prevention of breast cancer.

Targeting Breast Cancer-Derived Stem Cells by Dietary Phytochemicals: A Strategy for Cancer Prevention and Treatment

Breast cancer is heterogeneous disease with variable prognosis and therapeutic response. Approximately, 70% of diagnosed breast cancer represents the luminal A subtype. This subpopulation has a fair prognosis with a lower rate of relapse than the other clinical subtypes. Acquisition of stemness in luminal A subtype modifies the phenotype plasticity to accomplish increased aggressiveness and therapeutic resistance. Therefore, targeting luminal A-derived breast cancer stem cells (BCSCs) could be a promising strategy for its prevention and treatment. Extensive studies reveal that dietary phytochemicals have the potential to target BCSCs by modulating the molecular and signal transduction pathways. Dietary phytochemicals alone or in combination with standard therapeutic modalities exert higher efficacy in targeting BCSCs through changes in stemness, self-renewal properties and hypoxia-related factors. These combinations offer achieving higher radio- and chemo- sensitization through alteration in the key signaling pathways such as AMPK, STAT3, NF-ĸB, Hedgehog, PI3K/Akt/mTOR, Notch, GSK3β, and Wnt related to cancer stemness and drug resistance. In this review, we highlight the concept of targeting luminal A-derived BCSCs with dietary phytochemicals by summarizing the pathways and underlying mechanism(s) involved during therapeutic resistance.

Interleukin-30 feeds breast cancer stem cells via CXCL10 and IL23 autocrine loops and shapes immune contexture and host outcome

Background

Breast cancer (BC) progression to metastatic disease is the leading cause of death in women worldwide. Metastasis is driven by cancer stem cells (CSCs) and signals from their microenvironment. Interleukin (IL) 30 promotes BC progression, and its expression correlates with disease recurrence and mortality. Whether it acts by regulating BCSCs is unknown and could have significant therapeutic implications.

Methods

Human (h) and murine (m) BCSCs were tested for their production of and response to IL30 by using flow cytometry, confocal microscopy, proliferation and sphere-formation assays, and PCR array. Immunocompetent mice were used to investigate the role of BCSC-derived IL30 on tumor development and host outcome. TCGA PanCancer and Oncomine databases provided gene expression data from 1084 and 75 hBC samples, respectively, and immunostaining unveiled the BCSC microenvironment.

Results

hBCSCs constitutively expressed IL30 as a membrane-anchored glycoprotein. Blocking IL30 hindered their proliferation and self-renewal efficiency, which were boosted by IL30 overexpression. IL30 regulation of immunity gene expression in human and murine BCSCs shared a significant induction of IL23 and CXCL10. Both immunoregulatory mediators stimulated BCSC proliferation and self-renewal, while their selective blockade dramatically hindered IL30-dependent BCSC proliferation and mammosphere formation. Orthotopic implantation of IL30-overexpressing mBCSCs, in syngeneic mice, gave rise to poorly differentiated and highly proliferating MYC⁺KLF4⁺LAG3⁺ tumors, which expressed CXCL10 and IL23, and were infiltrated by myeloid-derived cells, Foxp3⁺ T regulatory cells and NKp46⁺RORγt⁺ type 3 innate lymphoid cells, resulting in increased metastasis and reduced survival. In tumor tissues from patients with BC, expression of IL30 overlapped with that of CXCL10 and IL23, and ranked beyond the 95th percentile in a Triple-Negative enriched BC collection from the Oncomine Platform. CIBERSORTx highlighted a defective dendritic cell, CD4⁺ T and γδ T lymphocyte content and a prominent LAG3 expression in IL30^highversus IL30^low human BC samples from the TCGA PanCancer collection.

Conclusions

Constitutive expression of membrane-bound IL30 regulates BCSC viability by juxtacrine signals and via second-level mediators, mainly CXCL10 and IL23. Their autocrine loops mediate much of the CSC growth factor activity of IL30, while their paracrine effect contributes to IL30 shaping of immune contexture. IL30-related immune subversion, which also emerged from computational analyses, strongly suggests that targeting IL30 can restrain the BCSC compartment and counteract BC progression.

Time-restricted feeding normalizes hyperinsulinemia to inhibit breast cancer in obese postmenopausal mouse models

Accumulating evidence indicates that obesity with its associated metabolic dysregulation, including hyperinsulinemia and aberrant circadian rhythms, increases the risk for a variety of cancers including postmenopausal breast cancer. Caloric restriction can ameliorate the harmful metabolic effects of obesity and inhibit cancer progression but is difficult to implement and maintain outside of the clinic. In this study, we aim to test a time-restricted feeding (TRF) approach on mouse models of obesity-driven postmenopausal breast cancer. We show that TRF abrogates the obesity-enhanced mammary tumor growth in two orthotopic models in the absence of calorie restriction or weight loss. TRF also reduces breast cancer metastasis to the lung. Furthermore, TRF delays tumor initiation in a transgenic model of mammary tumorigenesis prior to the onset of obesity. Notably, TRF increases whole-body insulin sensitivity, reduces hyperinsulinemia, restores diurnal gene expression rhythms in the tumor, and attenuates tumor growth and insulin signaling. Importantly, inhibition of insulin secretion with diazoxide mimics TRF whereas artificial elevation of insulin through insulin pumps implantation reverses the effect of TRF, suggesting that TRF acts through modulating hyperinsulinemia. Our data suggest that TRF is likely to be effective in breast cancer prevention and therapy.

Breast Cancer Stem Cells: Biomarkers, Identification and Isolation Methods, Regulating Mechanisms, Cellular Origin, and Beyond

Despite recent advances in diagnosis and treatment, breast cancer (BC) is still a major cause of cancer-related mortality in women. Breast cancer stem cells (BCSCs) are a small but significant subpopulation of heterogeneous breast cancer cells demonstrating strong self-renewal and proliferation properties. Accumulating evidence has proved that BCSCs are the driving force behind BC tumor initiation, progression, metastasis, drug resistance, and recurrence. As a heterogeneous disease, BC contains a full spectrum of different BC subtypes, and different subtypes of BC further exhibit distinct subtypes and proportions of BCSCs, which correspond to different treatment responses and disease-specific outcomes. This review summarized the current knowledge of BCSC biomarkers and their clinical relevance, the methods for the identification and isolation of BCSCs, and the mechanisms regulating BCSCs. We also discussed the cellular origin of BCSCs and the current advances in single-cell lineage tracing and transcriptomics and their potential in identifying the origin and lineage development of BCSCs.

A review of nanotechnology-based approaches for breast cancer and triple-negative breast cancer

Breast cancer (BC) is one of the most prevalent cancers in women. Triple-negative breast cancer (TNBC) in which the three major receptors i.e. estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), are absent is known to express the most aggressive phenotype and increased metastasis which results in the development of resistance to chemotherapy. It offers various therapeutic advantages in treating BC and TNBC. Nanotechnology offers various unique characteristics such as small size (nanometric), active and passive targeting, and the ability to attach multiple targeting moieties, controlled release, and site-specific targeting. This review focuses on conventional drug therapies, recent treatment strategies, and unique therapeutic approaches available for BC and TNBC. The role of breast cancer stem cells in the recurrence of BC and TNBC has also been highlighted. Several chemotherapeutic agents delivered using nanocarriers such as polymeric nanoparticles/micelles, metallic/inorganic NPs, and lipid-based NPs (Liposome, solid-lipid nanoparticles (SLNs), and nanostructured lipid carriers (NLCs)), etc. with excellent responses in the treatment of BC/TNBC along with breast cancer stem cells have been discussed in details. Moreover, the application of nanomedicine including CRISPR nanoparticle, exosomes for the treatment of BC/TNBC and other molecular targets available such as poly (ADP-ribose) polymerase (PARP), epidermal growth factor receptor (EGFR), Vascular endothelial growth factor (VEGF), etc. for further exploration have also been discussed.

Upregulation of annexin A1 protein expression in the intratumoral vasculature of human non-small-cell lung carcinoma and rodent tumor models

Annexin A1 (anxA1) is an immunomodulatory protein that has been proposed as a tumor vascular target for antitumor biologic agents, yet to date the vascular expression of anxA1 in specific tumor indications has not been systematically assessed. Attempts to evaluate vascular anxA1 expression by immunohistochemistry are complicated by a lack of available antibodies that are both specific for anxA1 and bind the N-terminal–truncated form of anxA1 that has previously been identified in tumor vasculature. To study the vascular expression pattern of anxA1 in non–small-cell lung carcinoma (NSCLC), we isolated an antibody capable of binding N-terminal–truncated anxA1_27-346 and employed it in immunohistochemical studies of human lung specimens. Lung tumor specimens evaluated with this antibody revealed vascular (endothelial) anxA1 expression in five of eight tumor samples studied, but no vascular anxA1 expression was observed in normal lung tissue. Tumor microarray analysis further demonstrated positive vascular staining for anxA1 in 30 of 80 NSCLC samples, and positive staining of neoplastic cells was observed in 54 of 80 samples. No correlation was observed between vascular and parenchymal anxA1 expression. Two rodent tumor models, B16-F10 and Py230, were determined to have upregulated anxA1 expression in the intratumoral vasculature. These data validate anxA1 as a potential vascular anti-tumor target in a subset of human lung tumors and identify rodent models which demonstrate anxA1 expression in tumor vasculature.

Reciprocal Signaling between Myeloid Derived Suppressor and Tumor Cells Enhances Cellular Motility and is Mediated by Structural Cues in the Microenvironment

Myeloid derived suppressor cells (MDSCs) have gained significant attention for their immunosuppressive role in cancer and their ability to contribute to tumor progression and metastasis. Understanding the role of MDSCs in driving cancer cell migration, a process fundamental to metastasis, is essential to fully comprehend and target MDSC-tumor cell interactions. This study employs microfabricated platforms, which simulate the structural cues present in the tumor microenvironment (TME) to elucidate the effects of MDSCs on the migratory phenotype of cancer cells at the single cell level. The results indicate that the presence of MDSCs enhances the motility of cancer-epithelial cells when directional cues (either topographical or spatial) are present. This behavior appears to be independent of cell-cell contact and driven by soluble byproducts from heterotypic interactions between MDSCs and cancer cells. Moreover, MDSC cell-motility is also impacted by the presence of cancer cells and the cancer cell secretome in the presence of directional cues. Epithelial dedifferentiation is the likely mechanism for changes in cancer cell motility in response to MDSCs. These results highlight the biochemical and biostructural conditions under which MDSCs can support cancer cell migration, and could therefore provide new avenues of research and therapy aimed at stemming cancer progression.

Cellular Plasticity in Breast Cancer Progression and Therapy

With the exception of non-melanoma skin cancer, breast cancer is the most frequently diagnosed malignant disease among women, with the majority of mortality being attributable to metastatic disease. Thus, even with improved early screening and more targeted treatments which may enable better detection and control of early disease progression, metastatic disease remains a significant problem. While targeted therapies exist for breast cancer patients with particular subtypes of the disease (Her2+ and ER/PR+), even in these subtypes the therapies are often not efficacious once the patient's tumor metastasizes. Increases in stemness or epithelial-to-mesenchymal transition (EMT) in primary breast cancer cells lead to enhanced plasticity, enabling tumor progression, therapeutic resistance, and distant metastatic spread. Numerous signaling pathways, including MAPK, PI3K, STAT3, Wnt, Hedgehog, and Notch, amongst others, play a critical role in maintaining cell plasticity in breast cancer. Understanding the cellular and molecular mechanisms that regulate breast cancer cell plasticity is essential for understanding the biology of breast cancer progression and for developing novel and more effective therapeutic strategies for targeting metastatic disease. In this review we summarize relevant literature on mechanisms associated with breast cancer plasticity, tumor progression, and drug resistance.

Induced Tumor Heterogeneity Reveals Factors Informing Radiation and Immunotherapy Combinations

PURPOSE

To investigate how induced tumor heterogeneity influences immune responses to radiotherapy with different proportions of mixed immune-responsive and unresponsive tumor cells in a triple-negative breast cancer model. It is hypothesized that studying the immune environment of mixed tumors and responses to radiotherapy could nominate immune active therapies to enhance immune responses after radiotherapy.

EXPERIMENTAL DESIGN

Evaluate efficacy and immune responses generated by radiotherapy in tumors with different proportions of immunologically responsive and unresponsive tumor cells. Then study the cellular responses and transcriptomic differences between the tumors to nominate immunotherapy combinations with radiotherapy and evaluate the combination.

RESULTS

The addition of the responsive cells to unresponsive tumors led to a greater than expected therapeutic response to radiotherapy with both innate and adaptive immune components. There was a distinct change in myeloid cells, greater inflammatory macrophage activity, and enhanced antigen presentation with responsive cells after radiotherapy. Because differences in matrix components, cell adhesion biology, and innate immune signaling correlated with myeloid cell response and phenotype, we hypothesized that radiotherapy combined with CD40 agonist antibody would sensitize unresponsive tumors. The combination therapy resulted in improved innate and adaptive immune response. Importantly, CD40 treatment increased tumor response to radiotherapy and protected against metastatic spread in a metastatic model.

CONCLUSIONS

These data combined with transcriptomics from human patients support radiotherapy and myeloid cell targeting for immunologically cold tumors. The established study model presents opportunities to investigate the complex overlapping biologic mechanisms that limit immunotherapy and to implement radiotherapy with different immunotherapy combinations.

Breast Cancer Stem Cells and Sex Steroid Hormones

Breast cancer stem cells (BCSCs) are a small population of tumor-initiating cells that express stem cell-associated markers. In recent years, their properties and mechanisms of regulation have become the focus of intense research due to their intrinsic resistance to conventional cancer therapies. This review describes breast cancer stem cell origin, signaling pathways involved in self-renewal, such as Wnt, Notch and Hedgehog, biomarkers linked to stemness, and the role of sex steroid hormones in BCSC regulation.

Comparative Profiling of Metastatic 4T1- vs. Non-metastatic Py230-Based Mammary Tumors in an Intraductal Model for Triple-Negative Breast Cancer

The transition of ductal carcinoma in situ (DCIS) to invasive carcinoma (IC) in breast cancer can be faithfully reproduced by the intraductal mouse model. Envisaging to use this model for therapeutic testing, we aimed to in-depth characterize the tumor immunity associated with the differential progression of two types of intraductal tumors. More specifically, we focused on triple-negative breast cancer (TNBC) and intraductally inoculated luciferase-expressing metastatic 4T1 and locally invasive Py230 cells in lactating mammary glands of syngeneic BALB/c and C57BL/6 female mice, respectively. Although the aggressive 4T1 cells rapidly formed solid tumors, Py230 tumors eventually grew to a similar size through enhanced proliferation. Yet, ductal tumor cell breakthrough and metastasis occurred earlier in the 4T1- compared to the Py230-based intraductal model and was associated with high expression of matrix metalloproteinase (MMP)-9, vascular endothelial growth factor (VEGF), chitinase 3-like 1 (CHI3L1) and lipocalin 2 (LCN2) as well as an increased influx of immune cells (mainly macrophages, neutrophils and T-cells). Moreover, activated cytotoxic T-cells, B-cells and programmed death-1 (PD-1)-positive cells were more prominent in the 4T1-based intraductal model in line with enhanced pro-inflammatory cytokine and gene expression profiles. Py230-based tumors showed a more immunosuppressed anti-inflammatory profile with a high amount of regulatory T-cells, which may account for the decreased T-cell activation but increased proliferation compared to the 4T1-based tumors. Taken together, our results highlight the differential immunological aspects of aggressive metastatic and non-aggressive intraductal progression of 4T1- vs. Py230-based tumors, providing a base for future studies to explore therapy using these intraductal TNBC models.

Secretomes from metastatic breast cancer cells, enriched for a prognostically unfavorable LCN2 axis, induce anti-inflammatory MSC actions and a tumor-supportive premetastatic lung

Cancer metastasis is responsible for the clear majority of cancer-related deaths. Survival and expansion of cancer cells at secondary sites requires that these premetastatic microenvironments be primed by primary tumor cells and their secreted factors. Efforts to date have been limited by immune-deficient in vivo models and/or the need for finely-tuned analysis time points that reduce contributions from early-disseminating cancer cells. In this regard, we developed a tumor cell-free syngeneic breast cancer model for characterizing tumor cell secretome-mediated reprogramming of premetastatic tissues. We demonstrate that secretomes from metastatic breast cancer cells differentially regulate the lung and brain, promoting a tumor-supportive lung microenvironment with both elevated CD73 expression and decreased TNFα expression. Using in vitro models of CD73-positive mesenchymal stem cells (MSCs) and macrophages/monocytes, we tested whether MSCs can mediate anti-inflammatory effects of metastatic breast cancer cells. Notably, conditioned media from metastatic Py230 cells reprogrammed the secretomes of MSCs toward an anti-inflammatory state. Mining transcriptome data from Py8119 and Py230 cells revealed a lipocalin 2 (LCN2) axis that is selectively expressed in the metastatic Py230 cells, predicts poor breast cancer patient survival and is elevated in circulating serum of mice chronically treated with conditioned media from Py230 cells. Taken together, these results establish the utility of an immune-competent tumor cell-free model for characterizing the mechanisms of breast cancer cell priming of the premetastatic niche, demonstrate that MSCs can mediate the anti-inflammatory effects of metastatic breast cancer cells and substantiate LCN2 as a promising therapeutic target for blocking breast cancer progression.

Breast cancer stem cells: Biology and therapeutic implications

Breast cancer remains to be a dreadful disease even with several advancements in radiation and chemotherapies, owing to the drug resistance and tumor relapse caused by breast cancer stem cells. Cancer stem cells are a minute population of cells of solid tumors which show self-renewal and differentiation properties as well as tumorigenic potential. Several signaling pathways including Notch, Hippo, Wnt and Hedgehog and tumor-stroma exchanges play a critical role in the self-renewal and differentiation of cancer stem cells in breast cancer. Cancer stem cells can grow anchorage-independent manner so they disseminate to different parts of the body to form secondary tumors. Cancer stem cells promote angiogenesis by dedifferentiating to endothelial cells as well as secreting proangiogenic and angiogenic factors. Moreover, multidrug resistance genes and drug efflux transporters expressed in breast cancer stem cells confer resistance to various conventional chemotherapeutic drugs. Indeed, these therapies are recognised to enhance the percent of cancer stem cell population in tumors leading to cancer relapse with increased aggressiveness. Hence, devising the therapeutic interventions to target cancer stem cells would be useful in increasing patients' survival rates. In addition, targeting the self-renewal pathways and tumor-stromal cross-talk helps in eradicating this population. Reversal of the cancer stem cell-mediated drug resistance would increase the sensitivity to various conventional drugs for the effective management of breast cancer. In this review, we have discussed the cancer stem cell origin and their involvement in angiogenesis, metastasis and therapy-resistance. We have also summarized different therapeutic approaches to eradicate the same for the successful treatment of breast cancer.

Transparent reporting of experimental parameters in assays measuring phenotypic steps in metastasis

Metastasis is key to cancer mortality. Understanding its biology is vital for developing strategies to prevent and treat metastasis. Phenotypic assays to either study metastasis or evaluate anti-metastatic drugs are widely used in preclinical research. This technical note discusses the adherence of reporting essential experimental and methodological parameters in chemotactic invasion assays in vitro and spontaneous metastasis assays in vivo. Following the analysis of 130 recent (< 5 years) research papers, several shortcomings in reporting were identified. Therefore, we strongly argue to increase experimental rigor which should result in a significant improvement with respect to reproducibility of preclinical metastasis research.

Impact of MMP-2 and MMP-9 enzyme activity on wound healing, tumor growth and RACPP cleavage

Matrix metalloproteinases-2 and -9 (MMP-2/-9) are key tissue remodeling enzymes that have multiple overlapping activities critical for wound healing and tumor progression in vivo. To overcome issues of redundancy in studying their functions in vivo, we created MMP-2/-9 double knockout (DKO) mice in the C57BL/6 background to examine wound healing. We then bred the DKO mice into the polyomavirus middle T (PyVmT) model of breast cancer to analyze the role of these enzymes in tumorigenesis. Breeding analyses indicated that significantly fewer DKO mice were born than predicted by Mendelian genetics and weaned DKO mice were growth compromised compared with wild type (WT) cohorts. Epithelial wound healing was dramatically delayed in adult DKO mice and when the DKO was combined with the PyVmT oncogene, we found that the biologically related process of mammary tumorigenesis was inhibited in a site-specific manner. To further examine the role of MMP-2/-9 in tumor progression, tumor cells derived from WT or DKO PyVmT transgenic tumors were grown in WT or DKO mice. Ratiometric activatable cell penetrating peptides (RACPPs) previously used to image cancer based on MMP-2/-9 activity were used to understand differences in MMP activity in WT or knockout syngeneic tumors in WT and KO animals. Analysis of an MMP-2 selective RACPP in WT or DKO mice bearing WT and DKO PyVmT tumor cells indicated that the genotype of the tumor cells was more important than the host stromal genotype in promoting MMP-2/-9 activity in the tumors in this model system. Additional complexities were revealed as the recruitment of host macrophages by the tumor cells was found to be the source of the tumor MMP-2/-9 activity and it is evident that MMP-2/-9 from both host and tumor is required for maximum signal using RACPP imaging for detection. We conclude that in the PyVmT model, the majority of MMP-2/-9 activity in mammary tumors is associated with host macrophages recruited into the tumor rather than that produced by the tumor cells themselves. Thus therapies that target tumor-associated macrophage functions have the potential to slow tumor progression.

Epigenetic and Transcriptomic Profiling of Mammary Gland Development and Tumor Models Disclose Regulators of Cell State Plasticity

Cell state reprogramming during tumor progression complicates accurate diagnosis, compromises therapeutic effectiveness, and fuels metastatic dissemination. We used chromatin accessibility assays and transcriptional profiling during mammary development as an agnostic approach to identify factors that mediate cancer cell state interconversions. We show that fetal and adult basal cells share epigenetic features consistent with multi-lineage differentiation potential. We find that DNA-binding motifs for SOX transcription factors are enriched in chromatin that is accessible in stem/progenitor cells and inaccessible in differentiated cells. In both mouse and human tumors, SOX10 expression correlates with stem/progenitor identity, dedifferentiation, and invasive characteristics. Strikingly, we demonstrate that SOX10 binds to genes that regulate neural crest cell identity, and that SOX10-positive tumor cells exhibit neural crest cell features.

Obesity promotes the expansion of metastasis-initiating cells in breast cancer

Background

Obesity is a strong predictor of poor prognosis in breast cancer, especially in postmenopausal women. In particular, tumors in obese patients tend to seed more distant metastases, although the biology behind this observation remains poorly understood.

Methods

To elucidate the effects of the obese microenvironment on metastatic spread, we ovariectomized C57BL/6 J female mice and fed them either a regular diet (RD) or a high-fat diet (HFD) to generate a postmenopausal diet-induced obesity model. We then studied tumor progression to metastasis of Py230 and EO771 grafts. We analyzed and phenotyped the RD and HFD tumors and the surrounding adipose tissue by flow cytometry, qPCR, immunohistochemistry (IHC) and western blot. The influence of the microenvironment on tumor cells was assessed by performing cross-transplantation of RD and HFD tumor cells into other RD and HFD mice. The results were analyzed using the unpaired Student t test when comparing two variables, otherwise we used one-way or two-way analysis of variance. The relationship between two variables was calculated using correlation coefficients.

Results

Our results show that tumors in obese mice grow faster, are also less vascularized, more hypoxic, of higher grade and enriched in CD11b⁺Ly6G⁺ neutrophils. Collectively, this favors induction of the epithelial-to-mesenchymal transition and progression to claudin-low breast cancer, a subtype of triple-negative breast cancer that is enriched in cancer stem cells. Interestingly, transplanting HFD-derived tumor cells in RD mice transfers enhanced tumor growth and lung metastasis formation.

Conclusions

These data indicate that a pro-metastatic effect of obesity is acquired by the tumor cells in the primary tumor independently of the microenvironment of the secondary site.

Graphical abstract

Effects of postmenopausal obesity on primary breast cancer tumoursᅟ

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1029-4) contains supplementary material, which is available to authorized users.

Correlation between ultrasonic features and expression levels of C-erbB-2, VEGF and nm23 in breast cancer

Breast cancer is one of the most common female malignancies in clinical practice, which ranks number one in terms of its high incidence. We investigated the relevance of ultrasonic features of breast cancer and expression levels of C-erbB-2, vascular endothelial growth factor (VEGF) and nm23 and its clinical significance. A total of 76 patients with breast cancer were recruited who were admitted to The Affiliated Hospital of Qingdao University from January, 2016 to August, 2017. All patients underwent color Doppler ultrasonic imaging, and expression levels of C-erbB-2, VEGF and nm23 in their tumor tissues were measured by immunohistochemistry. The ultrasonic features were evaluated and compared with the expression levels of C-erbB-2, VEGF and nm23 for each patient. Ultrasonography showed a tumor mass with spiculated margins, abnormal vasculature, and a diameter no less than 3 cm, as well as lymph node metastasis. The above signs were associated with high expression of C-erbB-2, VEGF and nm23 (p<0.05), but calcification was not associated with high expression of these biomarkers (p>0.05). For patients with highly expressed C-erbB-2 and VEGF, the time to peak (TTP) of the time-intensity curve obtained by contrast enhanced ultrasound was shorter, while the peak intensity (PI) was higher. On the contrary, for patients with highly expressed nm23, the TTP was apparently longer, while the PI was lower (p<0.05). The ultrasonic features of breast cancer were relevant to the expression levels of C-erbB-2, VEGF and nm23. Thus, the expression levels of C-erbB-2, VEGF and nm23 were predictable indirectly according to the ultrasonic features of the patient, which can be used as a reference for breast cancer treatment and prognosis prediction.

Evidence of drug-response heterogeneity rapidly generated from a single cancer cell

One cancer cell line is believed to be composed of numerous clones with different drug sensitivity. We sought to investigate the difference of drug-response pattern in clones from a cell line or from a single cell. We showed that 22 clones derived from 4T1 cells were drastically different from each other with respect to drug-response pattern against 11 anticancer drugs and expression profile of 19 genes associated with drug resistance or sensitivity. Similar results were obtained using daughter clones derived from a single 4T1 cell. Each daughter clone showed distinct drug-response pattern and gene expression profile. Similar results were also obtained using Bcap37 cells. We conclude that a single cancer cell can rapidly produce a population of cells with high heterogeneity of drug response and the acquisition of drug-response heterogeneity is random.

Fluorescence-Activated Cell Sorting of Murine Mammary Cancer Stem-Like Cell Subpopulations with HIF Activity

Fluorescence-activated cell sorting (FACS) is a common method to identify and to isolate subpopulations within a complex mixture of cells based on their light scatter and fluorescent staining profiles. FACS is widely used to enrich for normal tissue and tumor cells that have stem cell potential. Whereas FACS protocols using conventional breast cancer cell lines are relatively routine, additional technical challenges are encountered when sorting for cell populations from freshly digested solid tumors, particularly for use in downstream cancer stem cell (CSC) assays. First, it is more difficult to isolate live, single cells from whole tumors, and second, single tumor cells prepared from enzymatically digested tumors are typically more sensitive to cell death following the physical stresses of digestion, pipetting, and sorting. Herein methods are described that have been optimized to harvest and to FACS profile viable tumor epithelial cells digested from late-stage mammary tumors originating in the mouse mammary tumor virus (MMTV)-polyomavirus middle T antigen (PyMT) transgenic mouse. Protocols were designed to enrich for single, viable, MMTV-PyMT tumor cell populations sorted by FACS and to facilitate the collection of sorted cell subpopulations suitable for head-to-head comparison of CSC activity by tumorsphere assays in vitro or limiting dilution transplantation in vivo.

Breast cancer stem cells-from origins to targeted therapy

Breast cancer is marked as one of the leading causes of malignancy-related morbidities worldwide. In spite of aggressive interventions, the inevitability of relapse and metastasis severely impede survival rates. Mounting evidence highlight the insidious role of cancer stem cells (CSCs), a small but significant subpopulation of undifferentiated cells that drive tumour progression, spread and resistance to conventional therapy. The nature and significance of breast CSCs remains poorly understood, and even disputed by many researchers. This review discusses the origins, biomarkers, signalling pathways, regulatory mechanisms, and targeted therapy of breast CSCs.

Identification of miRNAs as biomarkers for acquired endocrine resistance in breast cancer

Therapies targeting estrogen receptor α (ERα) including tamoxifen, a selective estrogen receptor modulator (SERM) and aromatase inhibitors (AI), e.g., letrozole, have proven successful in reducing the death rate for breast cancer patients whose initial tumors express ERα. However, about 40% of patients develop acquired resistance to these endocrine treatments. There is a critical need to develop sensitive circulating biomarkers that accurately identify signaling pathways altered in breast cancer patients resistant to endocrine therapies. Serum miRNAs have the potential to serve as biomarkers of the progression of endocrine-resistant breast cancer due to their cancer-specific expression and stability. Exosomal transfer of miRNAs has been implicated in metastasis and endocrine-resistance. This review focuses on miRNAs in breast tumors and in serum, including exosomes, from breast cancer patients that are associated with resistance to tamoxifen since it is best-studied.

Primary patient-derived lung adenocarcinoma cell culture challenges the association of cancer stem cells with epithelial-to-mesenchymal transition

The cancer stem cell (CSC) and epithelial-to-mesenchymal transition (EMT) models have been closely associated and used to describe both the formation of metastasis and therapy resistance. We established a primary lung cell culture from a patient in a clinically rare and unique situation of primary resistant disease. This culture consisted of two biologically profoundly distinct adenocarcinoma cell subpopulations, which differed phenotypically and genotypically. One subpopulation initiated and sustained in spheroid cell culture (LT22s) whereas the other subpopulation was only capable of growth and proliferation under adherent conditions (LT22a). In contrast to our expectations, LT22s were strongly associated with the epithelial phenotype, and expressed additionally CSC markers ALDH1 and CD133, whereas the LT22a was characterized as mesenchymal with lack of CSC markers. The LT22s cells also demonstrated an invasive behavior and mimicked gland formation. Finally, LT22s were more resistant to Cisplatin than LT22a cells. We demonstrate a primary lung adenocarcinoma cell culture derived from a patient with resistant disease, with epithelial aggressive subpopulation of cells associated with stem cell features and therapy resistance. Our findings challenge the current model associating CSC and disease resistance mainly to mesenchymal cells and may have important clinical implications.

In vivo models in breast cancer research: progress, challenges and future directions

Research using animal model systems has been instrumental in delivering improved therapies for breast cancer, as well as in generating new insights into the mechanisms that underpin development of the disease. A large number of different models are now available, reflecting different types and stages of the disease; choosing which one to use depends on the specific research question(s) to be investigated. Based on presentations and discussions from leading experts who attended a recent workshop focused on in vivo models of breast cancer, this article provides a perspective on the many varied uses of these models in breast cancer research, their strengths, associated challenges and future directions. Among the questions discussed were: how well do models represent the different stages of human disease; how can we model the involvement of the human immune system and microenvironment in breast cancer; what are the appropriate models of metastatic disease; can we use models to carry out preclinical drug trials and identify pathways responsible for drug resistance; and what are the limitations of patient-derived xenograft models? We briefly outline the areas where the existing breast cancer models require improvement in light of the increased understanding of the disease process, reflecting the drive towards more personalised therapies and identification of mechanisms of drug resistance.

Reprogramming the immunological microenvironment through radiation and targeting Axl

Increasing evidence suggests that ionizing radiation therapy (RT) in combination with checkpoint immunotherapy is highly effective in treating a subset of cancers. To better understand the limited responses to this combination we analysed the genetic, microenvironmental, and immune factors in tumours derived from a transgenic breast cancer model. We identified two tumours with similar growth characteristics but different RT responses primarily due to an antitumour immune response. The combination of RT and checkpoint immunotherapy resulted in cures in the responsive but not the unresponsive tumours. Profiling the tumours revealed that the Axl receptor tyrosine kinase is overexpressed in the unresponsive tumours, and Axl knockout resulted in slower growth and increased radiosensitivity. These changes were associated with a CD8⁺ T-cell response, which was improved in combination with checkpoint immunotherapy. These results suggest a novel role for Axl in suppressing antigen presentation through MHCI, and enhancing cytokine release, which promotes a suppressive myeloid microenvironment.

Radiotherapy can enhance the antitumour immune response. Here, the authors show that resistance to radiation in breast cancer cells can be due to Axl expression that suppresses antigen presentation though MHCI, promotes NF-κB signalling, and enhances cytokine release promoting a suppressive myeloid microenvironment.

Lgr6 labels a rare population of mammary gland progenitor cells that are able to originate luminal mammary tumours

The mammary gland is composed of a complex cellular hierarchy with unusual postnatal plasticity. The identities of stem/progenitor cell populations, as well as tumour-initiating cells that give rise to breast cancer, are incompletely understood. Here we show that Lgr6 marks rare populations of cells in both basal and luminal mammary gland compartments in mice. Lineage tracing analysis showed that Lgr6+ cells are unipotent progenitors, which expand clonally during puberty but diminish in adulthood. In pregnancy or following stimulation with ovarian hormones, adult Lgr6+ cells regained proliferative potency and their progeny formed alveoli over repeated pregnancies. Oncogenic mutations in Lgr6+ cells resulted in expansion of luminal cells, culminating in mammary gland tumours. Conversely, depletion of Lgr6+ cells in the MMTV-PyMT model of mammary tumorigenesis significantly impaired tumour growth. Thus, Lgr6 marks mammary gland progenitor cells that can initiate tumours, and cells of luminal breast tumours required for efficient tumour maintenance.

Tumor Infiltrating Lymphocytes Affect the Outcome of Patients with Operable Triple-Negative Breast Cancer in Combination with Mutated Amino Acid Classes

Background

Stromal tumor infiltrating lymphocytes (TILs) density is an outcome predictor in triple-negative breast cancer (TNBC). Herein we asked whether TILs are related to coding mutation load and to the chemical class of the resulting mutated amino acids, i.e., charged, polar, and hydrophobic mutations.

Methods

We examined paraffin tumors from TNBC patients who had been treated with adjuvant chemotherapy mostly within clinical trials (training cohort, N = 133; validation, N = 190) for phenotype concordance; TILs density; mutation load and types.

Results

Concordance of TNBC phenotypes was 42.1% upon local / central, and 72% upon central / central pathology assessment. TILs were not associated with mutation load, type and class of mutated amino acids. Polar and charged mutation patterns differed between TP53 and PIK3CA (p<0.001). Hydrophobic mutations predicted for early relapse in patients with high nodal burden and <50% TILs tumors (training: HR 3.03, 95%CI 1.11–8.29, p = 0.031; validation: HR 2.90, 95%CI 0.97–8.70, p = 0.057), especially if compared to patients with >50% TILs tumors (training p = 0.003; validation p = 0.015).

Conclusions

TILs density is unrelated to mutation load in TNBC, which may be regarded as an unstable phenotype. If further validated, hydrophobic mutations along with TILs density may help identifying TNBC patients in higher risk for relapse.