Breast Cancer Lung Metastasis Research Articles

Lipid-laden lung mesenchymal cells foster breast cancer metastasis via metabolic reprogramming of tumor cells and natural killer cells

While the distant organ environment is known to support metastasis of primary tumors, its metabolic roles in this process remain underdetermined. Here, in breast cancer models, we found lung-resident mesenchymal cells (MCs) accumulating neutral lipids at the pre-metastatic stage. This was partially mediated by interleukin-1β (IL-1β)-induced hypoxia-inducible lipid droplet-associated (HILPDA) that subsequently represses adipose triglyceride lipase (ATGL) activity in lung MCs. MC-specific ablation of the ATGL or HILPDA genes in mice reinforced and reduced lung metastasis of breast cancer respectively, suggesting a metastasis-promoting effect of lipid-laden MCs. Mechanistically, lipid-laden MCs transported their lipids to tumor cells and natural killer (NK) cells via exosome-like vesicles, leading to heightened tumor cell survival and proliferation and NK cell dysfunction. Blockage of IL-1β, which was effective singly, improved the efficacy of adoptive NK cell immunotherapy in mitigating lung metastasis. Collectively, lung MCs metabolically regulate tumor cells and anti-tumor immunity to facilitate breast cancer lung metastasis.

Nanoadjuvants Actively targeting lymph node conduits and blocking tumor invasion in lymphatic vessels.

Great efforts have been made to manipulate nanoparticles (NPs) with a diameter of 10-100nm to passively target lymph nodes (LNs) to magnitude anti-tumor activity of T cells. However, no attention has been paid to increasing the retention of NPs with active affinity in order to induce a prolonged release of antigens or molecular adjuvants in the LNs mattering the immune response. Here, we formulated two NPs encapsulated with imiquimod (IMQ), a TLR7/8 agonist, and paclitaxel (PTX) and further modified them with tannic acid (TA), respectively, to generate IMQ NP and PTX NP with a final diameter of approximately 40nm. Attributing a strong affinity of TA molecules to the elastin of LN conduits, the TA modified IMQ NPs can bypass the gaps in the layer of lymphatic endothelial cells and enter the paracortex through the lymph node capsule-associated (LNC) conduits. Similarly, the TA modified PTX NPs increased delivery of PTX to the metastatic tumor site in LNs, where the tumor-associated antigens were released and presented by conduits-lining dendritic cells to activate T cells. Thus, the NPs with deposition to LN conduits showed excellent performance in preventing lymphovascular invasion of triple-negative breast cancer cells and lung metastasis thereafter. On the contrary, the NPs without TA flowed through the subcutaneous sinus existing LNs directly by efferent lymphatic vessels showing relatively poor therapeutic outcomes. This study reveals that TA may mediate the long retention of antigens and molecular adjuvants to be delivered to deep LNs for developing potent vaccination technology.

Natural small molecule self-assembled hydrogel inhibited tumor growth and lung metastasis of 4T1 breast cancer by regulating the CXCL1/2-S100A8/9 axis

It is crucial to inhibit tumor growth and distant metastasis for breast cancer (BC) therapy. However, the treatment primarily dependent on surgery, chemotherapy, and radiotherapy is far from satisfactory. It had been demonstrated that the CXCL1/2-S100A8/9 axis played an essential role in BC therapy. Therefore, we constructed a natural product hydrogel for BC therapy by blocking CXCL1 signaling. The GK-GA (phytochemicals of Genkwa Flos-glycyrrhizic acid) hydrogel was designed in a one-step “green” approach. The pharmacodynamics study showed GK-GA exhibited significant anti-tumor and anti-lung metastasis activities, resulting in the inhibition rate of tumor growth (IRG) over 90 % at 6.25 mg·kg−1, and did not display any obvious toxicity. In addition, the potent antitumor efficiency was also attributed to aggregation/assembly-induced retention (AIR) property. RNA sequencing analysis revealed the gene expression was significantly down-regulated in the GK-GA group, which were BCL2, CASP3, CXCL1, CXCL2, CXCR2, S100A8, S100A9, and confirmed further by western blot (WB). Our findings indicated natural product GK-GA hydrogel inhibited tumor growth and lung metastasis via the BCL2-CASP3 mitochondrial apoptosis pathway as well as the CXCL1/2-S100A8/9 pathway. This study provides inspiration for the fabrication of new excipients-free nano-dispersion in a one-step, no‐carrier‐added, organic solvent-free, “green” approach, particularly for small molecular antitumor agents.

Mannosylated engineered trichosanthin-legumain protein vaccine hydrogel for breast cancer immunotherapy

The development of cancer vaccines based on tumor-associated antigens is hurdled by lack of an efficient adjuvant and insufficient efficacy. To improve the efficacy of vaccines, a genetically-engineered method was employed in this work to achieve the codelivery of antigen and adjuvant to enhance immune responses. Trichosanthin is a plant-derived protein that possesses cancer immune stimulation function. A genetically engineered protein vaccine composed of trichosanthin (adjuvant) and legumain domain (a peptidic antigen) was constructed, which was further chemically modified with mannose for targeting dendritic cells (DCs). The method is facile and ready for scaling up for massive production. Such a “two-in-one” vaccine is advantageous for codelivery for augmenting the immune responses. The vaccine inhibited the tumors by triggering a robust cytotoxic T lymphocyte response in the orthotopic-breast-tumor mice. Furthermore, the vaccine was loaded into the temperature-sensitive hydrogel based on Pluronic F127 for implanting use in the post-surgical site. The sustained-released vaccine from the hydrogel inhibited not only the tumor recurrence but also the lung metastases of breast cancer. These findings demonstrated that it was a safe and effective vaccination for breast cancer immunotherapy in a prophylactical and therapeutical manner for remodeling the tumor immune microenvironment and arresting tumor growth.

Systemic pharmacological verification of Salvia miltiorrhiza-Ginseng Chinese herb pair in inhibiting spontaneous breast cancer metastasis

Breast cancer is the most commonly diagnosed cancer in the world, and metastasis is often the main cause of death in breast cancer patients. Salvia miltiorrhiza -Ginseng (SG) herb pair is clinically used for the treatment of cardiovascular diseases and cancers. However, the pharmacological action of this pair on breast cancer is yet unclear. In this study, a spontaneous metastasis model of breast cancer was constructed to assess the therapeutic value of SG. After administration of different doses of SG, the results showed that although it did not significantly inhibit tumor growth, high-dose SG administration could inhibit tumor metastasis. Then, based on systematic pharmacology combined with Gene Expression Omnibus (GEO) database, potential targets of drugs were identified such as vascular endothelial growth factor A (VEGFA), matrix metalloproteinase (MMP9), prostaglandin endoperoxide synthase2 (PTGS2), etc. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genome (KEGG) analysis revealed that these targets were related to cytokine-mediated signaling pathway, cell migration and other biological processes and signaling pathways such as PI3K/Akt, etc. The systematic pharmacology analysis showed that SG effectively inhibited the VEGFA and MMP9-mediated biological events such as angiogenesis, epithelial-mesenchymal transition (EMT) and impaired tumor metastasis. Overall, our research aimed to provide new ideas for the treatment of breast cancer lung metastasis in traditional Chinese medicine.

Application of a count data model to evaluate the anti-metastatic efficacy of QAP14 in 4T1 breast cancer allografts

Dopamine D1 receptor (D1DR) is proved to be a promising target to prevent tumor metastasis, and our previous studies showed that QAP14, a potent anti-cancer agent, exerted inhibitory effect on lung metastasis via D1DR activation. Therefore, the purpose of the study was to establish count data models to quantitatively characterize the disease progression of lung metastasis and assess the anti-metastatic effect of QAP14. Data of metastatic progression were collected in 4T1 tumor-bearing mice. Generalized Poisson distribution best described the variability of metastasis counts among the individuals. An empirical PK/PD model was developed to establish mathematical relationships between steady plasma concentrations of QAP14 and metastasis growth dynamics. The latency period of metastasis was estimated to be 12 days after tumor implantation. Our model structure also fitted well to other D1DR agonists (fenoldopam and l-stepholidine) which had inhibitory impact on breast cancer lung metastasis likewise. QAP14 40 mg/kg showed the best inhibitory efficacy, for it provided the longest prolongation of metastasis-free periods compared with fenoldopam or l-stepholidine. This study provides a quantitative method to describe the lung metastasis progression of 4T1 allografts, as well as an alternative PD model structure to evaluate anti-metastatic efficacy.

Neonicotinoid insecticides promote breast cancer progression via G protein-coupled estrogen receptor: In vivo, in vitro and in silico studies

Neonicotinoid insecticides (NIs) have been widely detected in environmental media and human body with concentrations reaching hundreds of nanomolar to micromolar levels. However, the information about their human health toxicology and mechanism is deficient. Previous studies have implied that NIs might exert estrogenic disruption and promote breast cancer progression, but the molecular mechanism is unclear, especially the molecular initiating event. G protein-coupled estrogen receptor (GPER), as a candidate therapeutic target, plays vital roles in the development of breast cancer. This work aimed to reveal the potential mechanism through GPER pathway. Firstly, we screened the activities of seven most common NIs on GPER signal pathway by calcium mobilization assay. Clothianidin, acetamiprid (ACE), and dinotefuran activated GPER most potently and ACE displayed the highest agonistic activity with the lowest observed effective concentration (LOEC) of 1 μM. The molecular docking and dynamics simulation showed favored interaction trend between the NIs and GPER. The three NIs with GPER activity induced 4T1 breast cancer cells migration and ACE showed the highest potency with LOEC of 100 nM. ACE also induced 4T1 cells proliferation at high concentration of 50 μM and up-regulated GPER expression in a dose-dependent manner. We speculated that both the induction effects of ACE on 4T1 cells proliferation and migration might be owing to the activation and up-regulation of GPER. By using 4T1-Luc cells injected orthotopic tumor model, we found that ACE also promoted in-situ breast cancer growth and lung metastasis in normal mouse dependent on GPER. However, ACE only promoted in-situ breast cancer growth through GPER but not lung metastasis in ovariectomized mice, implying that the ACE-induced lung metastasis should be related to endogenous estrogen from ovary. Overall, we demonstrated that NIs promoted breast cancer progression via GPER pathway at human related exposure levels and their female health risks need urgent concerns.

A yes-associated protein 1- Notch1 receptor positive feedback loop promotes breast cancer lung metastasis by attenuating the bone morphogenetic protein 4-SMAD family member 1/5 signaling.

The Notch1 (Notch1 receptor) and yes-associated protein 1 (YAP1) signaling can regulate breast cancer metastasis. This study aimed at investigating whether and how these two signal pathways crosstalk to promote breast cancer lung metastasis. Here, we show that YAP1 expression was positively correlated with Notch1 in breast cancer according to bioinformatics and experimental validation. Mechanistically, YAP1 with TEA domain transcription factors (TEADs) enhanced Jagged1(JAG1)-Notch1 signaling. Meanwhile, Notch1 promoted YAP1 stability in breast cancer cells by inhibiting the β-TrCP-mediated degradation, thereby, forming a YAP1- JAG1/Notch1 positive feedback loop in breast cancer. Furthermore, YAP1 enhanced the mammosphere formation and stemness of MDA-MB-231 cells by attenuating the inhibition of the BMP4-SMAD1/5 signaling. In vivo, the YAP1- JAG1/Notch1 positive feedback loop promoted the lung colonization of MDA-MB-231 cells. Our data for the first time indicate that the YAP1-Notch1 positive feedback loop promotes lung metastasis of breast cancer by modulating self-renewal and inhibiting the BMP4-SMAD1/5 signaling.

Machine learning-assisted elucidation of CD81-CD44 interactions in promoting cancer stemness and extracellular vesicle integrity.

Tumor-initiating cells with reprogramming plasticity or stem-progenitor cell properties (stemness) are thought to be essential for cancer development and metastatic regeneration in many cancers; however, elucidation of the underlying molecular network and pathways remains demanding. Combining machine learning and experimental investigation, here we report CD81, a tetraspanin transmembrane protein known to be enriched in extracellular vesicles (EVs), as a newly identified driver of breast cancer stemness and metastasis. Using protein structure modeling and interface prediction-guided mutagenesis, we demonstrate that membrane CD81 interacts with CD44 through their extracellular regions in promoting tumor cell cluster formation and lung metastasis of triple negative breast cancer (TNBC) in human and mouse models. In-depth global and phosphoproteomic analyses of tumor cells deficient with CD81 or CD44 unveils endocytosis-related pathway alterations, leading to further identification of a quality-keeping role of CD44 and CD81 in EV secretion as well as in EV-associated stemness-promoting function. CD81 is coexpressed along with CD44 in human circulating tumor cells (CTCs) and enriched in clustered CTCs that promote cancer stemness and metastasis, supporting the clinical significance of CD81 in association with patient outcomes. Our study highlights machine learning as a powerful tool in facilitating the molecular understanding of new molecular targets in regulating stemness and metastasis of TNBC.

342 (PB122) - Neutralizing antibody for S100A8/A9 soil sensing signal to prevent metastatic disease

Organotropism of cancer metastasis is driven by the ‘seed and soil’ theory where the soil (metastatic microenvironment) provides signals to attract the seeds (cancer cells) to grow on a certain location. S100A8/A9 is a ‘soil sensing signal’ that binds to receptors expressed by many cancer types. We aimed to understand the role of S100A8/A9 in melanoma, breast and lung cancer, to develop a neutralizing antibody, and to provide a proof-of-concept for the antibody for inhibiting metastasis. Cell lines were obtained from ATCC. Overexpression of S100A8/A9 receptors MCAM and NPTNβ was induced by cDNA vector and MCAM expression was silenced by a siRNA. Recombinant S100A8/A9 protein was produced in-house. Migration/invasion assays were performing with Boyden Chamber method, colony formation assay with agarose gel cultures, and the results were quantitated by counting crystal violet stained cells/colonies. mRNA expression was analyzed by qPCR. In mouse lung metastasis models, cancer cells were injected into tail vein, and lung metastases were monitored by X-ray Computed Tomography and quantitated by counting metastatic foci at endpoint. A chimeric S100A8/A9 antibody was produced in CHO-S cells by incorporating genomic sequences of heavy and light chains of a mouse monoclonal S100A8/A9 antibody to the Fab domain of human cDNA-encoded IgG2-Fc part. S100A8/A9 was expressed in monocytes and attracted cancer cells expressing its receptors to immunosuppressed premetastatic niche. Of these receptors, MCAM was highly expressed in metastatic, but not in non-metastatic melanoma and breast cancer cells. Overexpression of MCAM in non-metastatic melanoma cells increased migration, and downregulation in metastatic cells eliminated migration, but also resulted in lost sensitivity to S100A8/A9 stimulation. In breast cancer cells, overexpression of MCAM in non-metastastic cells increased migration, which was abrogated by addition of S100A8/A9 decoy receptor to the cultures. Overexpression of MCAM induced EMT-like expression profile in the breast cancer cells. In lung cancer, overexpression of S100A8/A9 receptor NPTNβ induced anchorage independent growth, migration and invasion, which were further increased by addition of S100A8/A9 ligand to the cultures. From the produced antibodies, the clones that efficiently bound S100A8 and A9 heterodimer most effectively inhibited migration and cytokine production. The S100A8/A9 antibody effectively prevented formation of lung metastases in melanoma and breast cancer lung metastasis models. These results demonstrate a role for S100A8/A9 and its receptors in metastasis of melanoma, breast and lung cancer. A neutralizing antibody for S100A8/A9 prevented formation of lung metastases, suggesting pharmacological inhibition of S100A8/A9 as a potential option for preventing metastatic disease. No conflict of interest.

Interleukin 4 Controls the Pro-Tumoral Role of Macrophages in Mammary Cancer Pulmonary Metastasis in Mice.

Simple SummaryMetastasis is the main cause of death from breast cancer. In mouse models of breast cancer lung metastasis, macrophages enhance metastasis by promoting tumor cell seeding and persistent growth. Here, we show that interleukin-4 (IL4) is required for this process as IL4 receptor (IL4rα)-null mice develop fewer and smaller lung metastases. This deficiency is partially rescued by adoptive transfer of wild-type monocytes. IL4 signaling in macrophages upregulates the expression of the chemokine receptor CXCR2, necessary for IL4-mediated tumor cell extravasation in vitro. In addition, expression of several other genes already causally associated with lung metastasis including Ccl2, Csf1, Ccr1, Hgf and Flt1 are upregulated in macrophages. High-resolution intravital imaging at the time of metastatic seeding showed reduced physical interaction between tumor cells and IL4rα-deficient macrophages, showing the dependence on IL4. We conclude that IL4 signaling in monocytes and macrophages is important during seeding and growth of breast metastasis in the lung.Metastasis is the systemic manifestation of cancer and the main cause of death from breast cancer. In mouse models of lung metastases, recruitment of classical monocytes from blood to the lung and their differentiation to metastasis-associated macrophages (MAMs) facilitate cancer cell extravasation, survival and growth. Ablation of MAMs or their monocytic progenitors inhibits metastasis. We hypothesized that factors controlling macrophage polarization modulate tumor cell extravasation in the lung. We evaluated whether signaling by Th1 or Th2 cytokines in macrophages affected transendothelial migration of tumor cells in vitro. Interferon gamma and LPS inhibited macrophage-dependent tumor cell extravasation while the Th2 cytokine interleukin-4 (IL4) enhanced this process. We demonstrated that IL4 receptor (IL4rα)-null mice developed fewer and smaller lung metastasis in E0771-LG mammary cancer models of this disease. Adoptive transfer of wild-type monocytes to IL4rα-deficient mice partially rescued this phenotype. IL4 signaling in macrophages controlled the expression of the chemokine receptor CXCR2, necessary for IL4-mediated tumor cell extravasation in vitro. Furthermore, IL4 signaling in macrophages regulated the transcript abundance of several other genes already causally associated with mammary cancer lung metastasis including Ccl2, Csf1, Ccr1, Hgf and Flt1. The central role of IL4 signaling in MAMs was confirmed by high-resolution intravital imaging of the lung in mice at the time of metastatic seeding, which showed reduced physical interaction between tumor cells and IL4rα-deficient macrophages. This interaction with wild-type MAMs enhanced tumor cell survival and seeding, which was lost in the IL4rα mice. These data indicate that IL4 signaling in monocytes and macrophages is key during seeding and growth of breast metastasis in the lung, as it regulates pro-tumoral paracrine signaling between cancer cells and macrophages.

Diagnostic and Prognostic Nomograms for Lung Metastasis in Triple-Negative Breast Cancer.

Background The lungs are one of the common sites of metastasis of triple-negative breast cancer (TNBC). Patients with lung metastases (LM) have a shorter duration of survival. This study is aimed at determining the prognostic factors of patients with TNBC with LM and constructing two nomograms to assess the risk of LM and the prognosis of patients with TNBC with LM. Methods Clinicopathological and follow-up data of patients with TNBC between 2010 and 2015 were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. Univariate and multivariate Cox regression analyses were used to screen for independent predictors of LM in patients with TNBC and identify the independent prognostic factors of patients with TNBC with LM. The two nomograms were appraised using calibration curves, receiver operating characteristic (ROC) curves, and decision curve analysis (DCA). Results A total of 27,048 patients with TNBC were included in this study. Age, tumour size, T stage, and N stage were identified as independent risk factors for LM in patients with TNBC. Histological type, marital status, prior surgery, chemotherapy, bone metastases, brain metastases, and LM were confirmed as independent prognostic factors for patients with TNBC with LM. The area under the ROC curve (AUC) of the diagnostic nomogram was 0.838 (95% confidence interval 0.817-0.860) in the training cohort and 0.894 (95% confidence interval 0.875-0.917) in the verification cohort. The AUC values of the 6-, 12-, and 18-month prognostic nomograms in the training cohort were 0.809 (95% confidence interval 0.771-0.868), 0.779 (95% confidence interval 0.737-0.834), and 0.735 (95% confidence interval 0.699-0.811), respectively, and the corresponding AUC values in the validation cohort were 0.735(95% confidence interval 0.642-0.820), 0.672 (95% confidence interval 0.575-0.758), and 0.705 (95% confidence interval 0.598-0.782), respectively. According to the calibration curves and data analysis, both nomograms exhibited good performance. Conclusion We successfully constructed and verified two valuable nomograms for predicting the incidence of LM and prognosis of patients TNBC with LM.

Tumor cell-released LC3-positive EVs promote lung metastasis of breast cancer through enhancing premetastatic niche formation.

Most breast cancer–related deaths are caused by metastasis in vital organs including the lungs. Development of supportive metastatic microenvironments, referred to as premetastatic niches (PMNs), in certain distant organs before arrival of metastatic cells, is critical in metastasis. However, the mechanisms of PMN formation are not fully clear. Here, we demonstrated that chemoattractant C–C motif chemokine ligand 2 (CCL2) could be stimulated by heat shock protein 60 (HSP60) on the surface of murine 4 T1 breast cancer cell–released LC3+ extracellular vesicles (LC3+ EVs) via the TLR2‐MyD88‐NF‐κB signal cascade in lung fibroblasts, which subsequently promoted lung PMN formation through recruiting monocytes and suppressing T cell function. Consistently, reduction of LC3+ EV release or HSP60 level or neutralization of CCL2 markedly attenuated PMN formation and lung metastasis. Furthermore, the number of circulating LC3+ EVs and HSP60 level on LC3+ EVs in the plasma of breast cancer patients were positively correlated with disease progression and lung metastasis, which might have potential value as biomarkers of lung metastasis in breast cancer patients (AUC = 0.898, 0.694, respectively). These findings illuminate a novel mechanism of PMN formation and might provide therapeutic targets for anti‐metastasis therapy for patients with breast cancer.

Intermedin (adrenomedullin 2) promotes breast cancer metastasis via Src/c-Myc-mediated ribosome production and protein translation.

Breast cancer is the most frequently diagnosed cancer and is the leading cause of cancer-associated mortality in women worldwide. Intermedin (IMD, also known as Adrenomedullin 2, ADM2) is an endogenous peptide that belongs to the calcitonin gene-related peptide family and has been reported to play important roles in several types of cancers, including breast cancer. In this study, we sought to investigate how IMD affects the behavior of breast cancer cells, the underlying mechanism of these effects, and whether blockade of IMD has a therapeutic effect against breast cancer. Transcriptome sequencing (RNA-Seq), cell biological experiments, Western blotting, immunoprecipitation, and animal tumor models were used. IMD expression was significantly increased in breast cancer samples, and the IMD level was positively correlated with lymph node metastasis and Ki67 expression. Cell biological experiments showed that IMD promoted the anchorage-independent growth, migration, and invasive ability of breast cancer cells. Inhibiting IMD activity with an anti-IMD monoclonal antibody blocked these tumor-promoting effects. In addition, blockade of IMD reduced in situ tumor growth and significantly decreased lung metastasis of 4T1 breast cancer in vivo. IMD induced Src kinase phosphorylation, which triggered the transcription of c-Myc, a major oncoprotein controlling the expression of genes that encode ribosomal components. Our data suggest that IMD is involved in breast cancer cell invasion and metastasis, potentially through increasing ribosome biogenesis and protein translation via the Src/c-Myc signaling pathway. These results suggest that IMD may be a novel target for the treatment of breast cancer.

Low-dose carbon monoxide suppresses metastatic progression of disseminated cancer cells

Low-dose carbon monoxide (CO) is under investigation in clinical trials to treat non-cancerous diseases and has an excellent safety profile. Due to early detection and cancer awareness, an increasing number of cancer patients are diagnosed at early stages, when potentially curative surgical resection can be done. However, many patients ultimately experience recurrence. Here, we evaluate the therapeutic effect of CO on metastatic cancer progression. We show that 250 ppm CO inhibits the migration of multiple types of cancer cell lines, including breast, pancreatic, colon, prostate, liver, and lung cancer and reduces the ability to adhere to fibronectin. We demonstrate that in mouse models, 250 ppm inhaled CO inhibits lung metastasis of breast cancer and liver metastasis of pancreatic cancer. Moreover, low-dose CO suppresses recurrence and increases survival after surgical removal of primary pancreatic cancer in mice. Mechanistically, low-dose CO blocks transcription of heme importers, leading to diminished intracellular heme levels and a heme-regulated enzyme, cytochrome P4501B1 (CYP1B1). Either supplementing heme or overexpressing CYP1B1 reverses the anti-migration effect of low-dose CO. Taken together, low-dose CO therapy inhibits cell migration, reduces adhesion to fibronectin, prevents disseminated cancer cells from expanding into gross metastases, and improves survival in pre-clinical mouse models of metastasis.

Possible Metastatic Stage-Dependent ILC2 Activation Induces Differential Functions of MDSCs through IL-13/IL-13Rα1 Signaling during the Progression of Breast Cancer Lung Metastasis.

Simple SummaryWhen breast cancer metastasizes to the lung, group 2 innate lymphoid cells (ILC2s) are thought to promote tumor growth via the activation of myeloid-derived suppressor cells (MDSCs). In this study, we aimed to characterize the dynamic interactions of ILC2s and MDSCs during the course of cancer progression from the micrometastatic to the macrometastatic stages. We found that ILC2s were activated in both the micro- and macrometastatic regions, suggesting sustained activation throughout the metastatic cascades. In addition, our findings indicate that ILC2s may induce the immunosuppressive functions of MDSCs during the later stages of metastasis. Concomitantly, ILC2 may instigate extracellular matrix remodeling by polymorphonuclear (PMN)-MDSC activation during the early stages of metastasis. These metastatic-stage-specific changes may contribute to metastatic tumor growth in the microenvironment of breast cancer lung metastasis.Breast cancer is the most common cancer in women worldwide, and lung metastasis is one of the most frequent distant metastases. When breast cancer metastasizes to the lung, group 2 innate lymphoid cells (ILC2s) are thought to promote tumor growth via the activation of myeloid-derived suppressor cells (MDSCs), which are known to negatively regulate anticancer immune responses. However, it remains to be elucidated exactly how this ILC2–MDSC interaction is involved in tumor growth during metastases formation. Using a 4T1/LM4 breast cancer mouse model, we found that ILC2s were activated in both the micro- and macrometastatic regions, suggesting sustained activation throughout the metastatic cascades via IL-33/ST2 signaling. Consistent with IL-13 secretion from activated ILC2s, the frequencies of polymorphonuclear (PMN)- and monocytic (M)-MDSCs were also significantly elevated during the progression from micro- to macrometastatic cancer. However, the effects of ILC2-induced MDSC functionality on the microenvironment differed in a metastatic-stage-specific manner. Our findings indicate that ILC2s may induce the immunosuppressive functions of MDSCs during the later stages of metastasis. Concomitantly, ILC2 may instigate extracellular matrix remodeling by PMN-MDSC activation during the early stages of metastasis. These metastatic-stage-specific changes may contribute to metastatic tumor growth in the microenvironment of breast cancer lung metastasis.

HAO1-mediated oxalate metabolism promotes lung pre-metastatic niche formation by inducing neutrophil extracellular traps

Metabolic reprogramming has been shown to be involved in cancer-induced pre-metastatic niche (PMN) formation, but the underlying mechanisms have been insufficiently explored. Here, we showed that hydroxyacid oxidase 1 (HAO1), a rate-limiting enzyme of oxalate synthesis, was upregulated in the alveolar epithelial cells of mice bearing metastatic breast cancer cells at the pre-metastatic stage, leading to oxalate accumulation in lung tissue. Lung oxalate accumulation induced neutrophil extracellular trap (NET) formation by activating NADPH oxidase, which facilitated the formation of pre-metastatic niche. In addition, lung oxalate accumulation promoted the proliferation of metastatic cancer cells by activating the MAPK signaling pathway. Pharmacologic inhibition of HAO1 could effectively suppress the lung oxalate accumulation induced by primary cancer, consequently dampening lung metastasis of breast cancer. Breast cancer cells induced HAO1 expression and oxalate accumulation in alveolar epithelial cells by activating TLR3-IRF3 signaling. Collectively, these findings underscore the role of HAO1-mediated oxalate metabolism in cancer-induced lung PMN formation and metastasis. HAO1 could be an appealing therapeutic target for preventing lung metastasis of cancer.

Elevated BCAA Suppresses the Development and Metastasis of Breast Cancer.

Branched-chain amino acids (BCAAs) are the three essential amino acids including leucine, isoleucine, and valine. BCAA metabolism has been linked with the development of a variety of tumors. However, the impact of dietary BCAA intake on breast tumor progression and metastasis remains to be fully explored. Here, we unexpectedly find that the elevated BCAA, either in the genetic model or via increasing dietary intake in mice, suppresses the tumor growth and lung metastasis of breast cancer. The survival analysis shows that BCAA catabolic gene expression is strongly associated with long-term oncological outcomes in patients with breast cancer. In Pp2cm knockout mice in which BCAAs accumulate due to the genetic defect of BCAA catabolism, the breast tumor growth is suppressed. Interestingly, while the cell proliferation and tumor vasculature remain unaffected, more cell death occurs in the tumor in Pp2cm knockout mice, accompanied with increased natural killer (NK) cells. Importantly, increasing BCAA dietary intake suppresses breast tumor growth in mice. On the other hand, there are fewer lung metastases from primary breast tumor in Pp2cm knockout mice and the high BCAA diet-fed mice, suggesting high BCAA also suppresses the lung metastasis of breast cancer. Furthermore, low BCAA diet promotes lung colonization of breast cancer cells in tail vein model. The migration and invasion abilities of breast cancer cells are impaired by high concentration of BCAA in culture medium. The suppressed tumor metastasis and cell migration/invasion abilities by elevated BCAA are accompanied with reduced N-cadherin expression. Together, these data show high BCAA suppresses both tumor growth and metastasis of breast cancer, demonstrating the potential benefits of increasing BCAA dietary intake in the treatment of breast cancer.

Abstract 6123: High-fat diets promote lung metastasis of breast cancer by activating lung fibroblasts

Abstract Metastasis is the main cause of patient death among many tumor types including breast cancer and breast cancer patients with obesity have higher risk of distant metastases during 10-year follow-up. Diet is one of the main and manageable factors that cause obesity and regular intake of high-fat diets can induce obesity. In addition, fibroblasts, as the most abundant stromal cell type in tumor microenvironment, are involved in cancer metastasis. However, the role of fibroblasts and the downstream mechanism in metastasis of patients with high-fat diet remains unclear. In this study, we fed MMTV-PyMT transgenic mice with high-fat diet to obtain a high-fat tumorigenesis model, and isolate primary lung fibroblasts and then coculture them with breast cancer cells to explore the interaction. We found that a high-fat diet can significantly promote progression of primary breast cancer and lung metastasis, and that before weight difference shows, there is a different chemotactic influence of lung fibroblasts on breast cancer cell between high-fat diet and normal diet group. And we observed increased chemotactic function of primary lung fibroblasts in high-fat diet group. Moreover, tumor cells treated with primary lung fibroblasts in high-fat diet group show increased ability of adhesion, suggesting that high-fat diet chemoattracts breast cancer cell colonization by activating lung fibroblasts. Collectively, we explored the functional differences of lung fibroblast and the key factors for the lung colonization of recruited breast cancer cells. Our findings suggest that dietary patterns are associated with the risk of breast cancer metastasis and targeting activated fibroblasts in pre-metastatic microenvironment may serve as potential early therapeutic strategy to reduce breast cancer lung metastasis. Citation Format: Huiping Chen, Penghan Huang, Jianing Chen, Erwei Song. High-fat diets promote lung metastasis of breast cancer by activating lung fibroblasts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6123.

Abstract 5983: Gene profile analysis of breast cancer lung metastasis, liver metastasis, brain metastasis and primary tumor

Abstract Background: The incidence of male breast cancer (MBC) is lower than female breast cancer (FBC), representing 1% of all breast cancer worldwide. The difference with FBC may affect the treatment strategy of MBC, but the necessary precondition is that we should know more about the difference between FBC and MBC. However, Because of its low incidence that the relevant data about MBC is relatively scarce. Here we report some data about gene mutation of MBC, and compared it with FBC. Methods: Blood or tumor Tissue samples of breast cancer were collected and subjected to NGS in a College of American Pathologists (CAP)-certified and Clinical Laboratory Improvement Amendments (CLIA)-accredited lab for gene mutation analysis (3D Medicines Inc.,Shanghai, China). Statistical analysis was performed using GraphPad Prism (version 7.01) and SPSS version 21.0 (SPSS,Inc.). Results: Approximately 182 samples were analyzed, among which, exist 82 samples were from primary tissue, 66 samples were breast cancer liver metastases, 20 were lung metastases and 14 were brain metastases. High genomic heterogeneity was found among primary breast cancer tissue, breast cancer liver metastases, lung metastases, brain metastases, that is at least 20 gene mutations were found in these BC samples, while different gene mutations were showed among primary and different metastases tissues. The top five mutated gene in primary tumor tissue were TP53(80.49%), PIK3CA(53.66%), FGF19(30.49%), ERBB2(26.83%), MYC(23.17%); in liver metastases tissues were TP53(54.55%), FGF19(39.39%), PIK3CA(37.88%), ERBB2(21.21%), CCND1(19.70%); in lung metastases tissues were TP53(70.00%), PIK3CA(55.00%), ERBB2,MCL1(25.00%), CDKN2A/2B(20.00%), CCND1, NF1, CDK12(15.00%), CCND2, MYC, PTEN, GNAS, FGF19, PTK2, FGFR1(10.00%); in brain metastases tissues were TP53(42.86%), PIK3CA(28.57%), ZNF703, PREX2, JAK3, MYC, FGFR1(14.29%). Besides, levels of TMB were also different among primary tissue, liver, lung and brain metastases tissues. Higher TMB level were showed in liver and brain metastases tissue than primary and lung metastases tissues (p<0.001). Conclusions: Different metastases of breast cancer were different in gene mutation landscape, this imply these patients should be managed differently. Citation Format: Yanman Fang, Hushan Zhang, Jiali Zou, Fulin Zhou, Xuejie Tang, Yi Yang, Li Luo, Yu Ding. Gene profile analysis of breast cancer lung metastasis, liver metastasis, brain metastasis and primary tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5983.