Breast Tumor Growth Research Articles

α-Catenin acetylation is essential for its stability and blocks its tumor suppressor effects in breast cancer through Yap1.

α-Catenin plays a critical role in tissue integrity, repair, and embryonic development. However, the post-translational modifications of α-catenin and the correlative roles in regulating cancer progression remain unclear. Here, we report that α-catenin is acetylated by p300, and identify three acetylation sites, K45, K866, and K881. Conversely, α-catenin acetylation can be reversed by deacetylase HDAC6. Mechanistically, α-catenin acetylation releases the transcriptional coactivator Yes-associated protein 1 (Yap1) by blocking the interaction between α-catenin and Yap1, and promotes the accumulation of Yap1 in the nucleus. Through this mechanism, acetylation weakens the capacity of α-catenin to inhibit breast cancer cell proliferation and tumor growth in mice. Meanwhile, we show that CDDP induces acetylation of α-catenin, and acetylated α-catenin resists the apoptosis under CDDP conditions. Additionally, acetylation inhibits the proteasome-dependent degradation of α-catenin, thus enhancing the stability of α-catenin for storage. Taken together, our results demonstrate that α-catenin can be acetylated, an event that is key for the subcellular distribution of Yap1 and subsequent facilitation of breast tumorigenesis.

A mitochondrial EglN1-AMPKα axis drives breast cancer progression by enhancing metabolic adaptation to hypoxic stress.

Mitochondria play essential roles in cancer cell adaptation to hypoxia, but the underlying mechanisms remain elusive. Through mitochondrial proteomic profiling, we here find that the prolyl hydroxylase EglN1 (PHD2) accumulates on mitochondria under hypoxia. EglN1 substrate-binding region in the β2β3 loop is responsible for its mitochondrial translocation and contributes to breast tumor growth. Furthermore, we identify AMP-activated protein kinase alpha (AMPKα) as an EglN1 substrate on mitochondria. The EglN1-AMPKα interaction is essential for their mutual mitochondrial translocation. After EglN1 prolyl-hydroxylates AMPKα under normoxia, they rapidly dissociate following prolyl-hydroxylation, leading to their immediate release from mitochondria. In contrast, hypoxia results in constant EglN1-AMPKα interaction and their accumulation on mitochondria, leading to the formation of a Ca2+ /calmodulin-dependent protein kinase 2 (CaMKK2)-EglN1-AMPKα complex to activate AMPKα phosphorylation, ensuring metabolic homeostasis and breast tumor growth. Our findings identify EglN1 as an oxygen-sensitive metabolic checkpoint signaling hypoxic stress to mitochondria through its β2β3 loop region, suggesting a potential therapeutic target for breast cancer.

ERCC6L facilitates the onset of mammary neoplasia and promotes the high malignance of breast cancer by accelerating the cell cycle

BackgroundBreast cancer (BC) is the leading cause of morbidity and the second leading cause of death among female malignant tumors. Although available drugs have been approved for the corresponding breast cancer subtypes (ER-positive, HER2+) currently, there are still no effective targeted drugs or treatment strategies for metastatic breast cancer or triple-negative breast cancer that lack targets. Therefore, it is urgent to discover new potential targets. ERCC6L is an essential protein involved in chromosome separation during cell mitosis. However, the effect of ERCC6L on the tumorigenesis and progression of breast cancer is unclear.Methods and resultsHere, we found that ERCC6L was highly expressed in breast cancer, especially in TNBC, which was closely related to poor outcomes of patients. An ERCC6L conditional knockout mouse model was first established in this study, and the results confirmed that ERCC6L was required for the development of the mammary gland and the tumorigenesis and progression of mammary gland cancers. In in vitro cell culture, ERCC6L acted as a tumor promoter in the malignant progression of breast cancer cells. Overexpression of ERCC6L promoted cell proliferation, migration and invasion, while knockdown of ERCC6L caused the opposite results. Mechanistically, ERCC6L accelerated the cell cycle by regulating the G2/M checkpoint signalling pathway. Additionally, we demonstrated that there is an interaction between ERCC6L and KIF4A, both of which are closely related factors in mitosis and are involved in the malignant progression of breast cancer.ConclusionsWe first demonstrated that ERCC6L deficiency can significantly inhibit the occurrence and development of mammary gland tumors. ERCC6L was found to accelerate the cell cycle by regulating the p53/p21/CDK1/Cyclin B and PLK/CDC25C/CDK1/Cyclin B signalling pathways, thereby promoting the malignant progression of breast cancer cell lines. There was a direct interaction between KIF4A and ERCC6L, and both are closely associated with mitosis and contribute to growth and metastasis of breast tumor. To sum up, our results suggest that ERCC6L may be used as a promising target for the treatment of BC.

Neoantigen-Based Nanovaccine In Combination with Immune Checkpoint Inhibitors Abolish Postsurgical Tumor Recurrence and Metastasis.

The notorious limitation of conventional surgical excision of primary tumor is the omission of residual and occult tumor cells, which often progress to recurrence and metastasis, leading to clinical treatment failure. The therapeutic vaccine is emerging as a promising candidate for dealing with the issue of postsurgical tumor residuals or nascent metastasis. Here, a flexible and modularized nanovaccine scaffold based on the SpyCatcher003-decorated shell (S) domain of norovirus (Nov) is employed to support the presentation of varied tumor neoantigens fused with SpyTag003. The prepared tumor neoantigen-based nanovaccines (Neo-NVs) are able to efficiently target to lymph nodes and engage with DCs in LNs, triggering strong antigen-specific T-cell immunity and significantly inhibiting the growth of established orthotopic 4T1 breast tumor in mice. Further, the combination of Neo-NVs and anti-PD-1 monoclonal antibody (mAb) produces significant inhibition on postsurgical tumor recurrence and metastasis and induces a long-lasting immune memory. In conclusion, the study provides a simple and reliable strategy for rapid preparing personalized neoantigens-based cancer vaccines and engaging checkpoint treatment to restore the capability of tumor immune surveillance and clearance in surgical patients.

Topical Calcipotriol Plus Imiquimod Immunotherapy for Nonkeratinocyte Skin Cancers

Nonkeratinocyte cutaneous malignancies, including breast cancer cutaneous metastasis and melanoma in situ, are often poor surgical candidates. Imiquimod (IMQ), a toll-like receptor 7 agonist that activates innate immunity in the skin, is used to treat these cutaneous malignancies. However, IMQ's modest effect on the activation of adaptive immunity limits its efficacy as a monotherapy. In this study, we demonstrate that topical TSLP cytokine inducers-calcipotriol and retinoic acid-synergize with IMQ to activate CD4+ T-cell immunity against nonkeratinocyte cutaneous malignancies. Topical calcipotriol plus IMQ treatment reduced breast tumor growth compared with calcipotriol or IMQ alone (P < 0.0001). Calcipotriol plus IMQ-mediated tumor suppression was associated with significant infiltration of CD4+ effector T cells in the tumor microenvironment. Notably, topical calcipotriol plus IMQ immunotherapy enabled immune checkpoint blockade therapy to effectively control immunologically cold breast tumors, which was associated with induction of CD4+ T-cell immunity. Topical treatment with calcipotriol plus IMQ and retinoic acid plus IMQ also blocked subcutaneous melanoma growth. These findings highlight the synergistic effect of topical TSLP induction in combination with innate immune cell activation as an effective immunotherapy for malignancies affecting the skin.

Chitosan Thermosensitive Hydrogel Based on DNA Damage Repair Inhibition and Mild Photothermal Therapy for Enhanced Antitumor Treatment.

The DNA damage repair of tumor cells limits the effect of photothermal therapy (PTT), and high temperatures induced by PTT can damage adjacent normal tissues. To overcome these limitations, we developed a novel composite hydrogel (OLA-Au-Gel) based on chitosan (CS) and β-glycerophosphate (β-GP), which encapsulated olaparib-liposomes (OLA-lips) and CS-capped gold nanoparticles (CS-AuNPs). OLA-Au-Gel achieved the combination of mild PTT (mPTT) by CS-AuNPs and tumor DNA damage repair inhibition by OLA. The hydrogel showed good biocompatibility, injectability, and photothermal response. Under near-infrared laser irradiation, OLA-Au-Gel inhibited the proliferation of tumor cells, induced the generation of reactive oxygen species in vitro, and effectively inhibited the growth of breast tumors in vivo. OLA-Au-Gel shows a promising application prospect for inhibiting tumor development and improving the antitumor effect. Collectively, we propose a novel strategy for enhanced antitumor therapy based on the combination of mPTT and DNA damage repair inhibition.

Lycorine suppresses the malignancy of breast carcinoma by modulating epithelial mesenchymal transition and β-catenin signaling

Lycorine, an isoquinoline alkaloid can exhibit significant anti-cancer effects. The present study was conducted to illustrate the underlying mechanisms of action of lycorine on breast carcinoma under in vitro and in vivo settings Tandem Mass Tag assay and Kyoto Encyclopedia of Genes and Genomes analysis revealed that 20 signaling pathways were closely related to tumorigenesis, especially Wnt signaling pathway and tight junctions. The results demonstrated that lycorine evidently inhibited the proliferation of MDA-MB-231 and MCF-7 cells with IC50 values of 1.84 ± 0.21 μM and 7.76 ± 1.16 μM, respectively. It also blocked cell cycle in G2/M phase, caused a decrease in mitochondrial membrane potential, and induced apoptosis pathways through regulating caspase-3, caspase-8, caspase-9, and PARP expression. Moreover, lycorine effectively repressed the β-catenin signaling and reversed epithelial-mesenchymal transition (EMT) process. Furthermore, 4T1/Luc homograft tumor model was used to further demonstrate that lycorine significantly inhibited the growth and metastasis of breast tumor. These findings highlight the significance of lycorine as potential anti-neoplastic agent to combat breast cancer.

Prox1 Suppresses the Proliferation of Breast Cancer Cells via Direct Inhibition of c-Myc Gene Expression.

Breast cancer is one of the most lethal malignancies in women worldwide and is characterized by rapid growth and low survival rates, despite advances in tumor biology and therapies. Novel therapeutic approaches require new insights into the molecular mechanisms of malignant transformation and progression. To this end, here, we identified Prox1 as a negative regulator of proliferation and tumor-related metabolism in breast cancer. In particular, we showed that breast tumors from human patients exhibited reduced levels of Prox1 expression, while high expression levels of Prox1 were associated with a favorable prognosis in breast cancer patients. Moreover, we experimentally demonstrated that Prox1 was sufficient to strongly suppress proliferation, migration, and the Warburg effect in human breast cancer cells without inducing apoptosis. Most importantly, over-expression of Prox1 inhibited breast tumor growth in vivo in both heterotopic and orthotopic xenograft mouse models. The anti-tumorigenic effect of Prox1 was mediated by the direct repression of c-Myc transcription and its downstream target genes. Consistently, c-Myc over-expression from an artificial promoter that was not targeted by Prox1 reversed Prox1's anti-tumor effects. These findings suggest that Prox1 has a tumor suppressive role via direct transcriptional regulation of c-Myc, making it a promising therapeutic gene for breast cancer.

Estrogen receptor α-mediated signaling inhibits type I interferon response to promote breast carcinogenesis.

Estrogen receptor α (ERα)is an important driver and therapeutic target in ∼70% of breast cancers. How ERαdrives breast carcinogenesis is not fully understood. In this study, we show that ERαis a negative regulator of type I interferon (IFN) response. Activation of ERα by its natural ligand estradiol inhibits IFN-β-induced transcription of downstream IFN-stimulated genes (ISGs), whereas ERα deficiency or the stimulation with its antagonist fulvestrant has opposite effects. Mechanistically, ERα induces the expression of the histone 2A variant H2A.Z to restrict the engagement of the IFN-stimulated gene factor 3 (ISGF3) complex to the promoters of ISGs and also interacts with STAT2 to disrupt the assembly of the ISGF3 complex. These two events mutually lead to the inhibition of ISG transcription induced by type I IFNs. In a xenograft mouse model, fulvestrant enhances the ability of IFN-β to suppress ERα+ breast tumor growth. Consistently, clinical data analysis reveals that ERα+ breast cancer patients with higher levels of ISGs exhibit higher long-term survival rates. Taken together, our findings suggest that ERαinhibits type I IFN response via two distinct mechanisms to promote breast carcinogenesis.

A Novel Bromophenol Compound from Leathesia nana Inhibits Breast Cancer in a Direct Tumor Killing and Immunotherapy Manner.

Considering the resistance and toxicity of traditional chemotherapeutic drugs, seeking potential candidate for treating breast cancer effectively is a clinical problem that should be solved urgently. Natural products have attracted extensive attention, owing to their multi-target advantages and low toxicity. In the current study, the effects of XK-81, a novel bromophenol compound extracted from Leathesia nana, on breast cancer, and its underlying mechanisms, were explored. Firstly, data from in vitro experiments indicated that 4T-1, one of common mouse breast cancer cell lines, was a XK-81-susceptible cell line, and ferroptosis was the major death manner in response to XK-81 treatment, which was evidenced by increasing intracellular Fe2+ and ROS level with condensed mitochondrial membrane densities, as well as decreasing the protein expressions of SLC7A11 and GPX4. In vivo, XK-81 suppressed the growth of 4T-1 breast-tumor in both BALB/C mice and zebrafish. Obviously, XK-81 decreased the protein expression of SLC7A11 and GPX4 in tumor tissues, hinting at the occurrence of ferroptosis. Moreover, XK-81 increased CD8+ T cells and NK cells numbers and regulated M1/M2 macrophage ratio in tumor tissues, indicating XK-81's immunotherapeutic effect. Additionally, the secretions of immune-related cytokines, including TNF-α, IL-1β, and IL-12, were elevated with XK-81 stimulation in RAW 264.7 cells. Intriguingly, compared with doxorubicin-induced heart damage, XK-81 demonstrated the therapeutic advantage of little cardiotoxicity on the heart. XK-81 demonstrated potential antitumor advantage by both directly inducing ferroptosis-mediated death of tumor cells and immunization.

Anti-tumor effects of Bacteroides fragilis and Bifidobacterium bifidum culture supernatants on mouse breast cancer

Breast cancer is one of the most important causes of cancer related morbidity and mortality in the world. Breast contains several bacterial species performing specialized functions. Bacteroides and Bifidobacterium, as microbial flora, play pivotal role against breast cancer development in vivo and in vitro. In this study we evaluated the anti-proliferative and anti-tumor effects of Bacteroides fragilis (F.S), Bifidobacterium bifidum (B.S) and Bifidobacterium bifidum + Bacteroides fragilis supernatants (B.F.S) in in vivo and in vitro model of 4 T1 cell line breast cancer. Bacterial supernatants assessed in both model. Our results indicated that the relative tumor volume significantly increased in the mice receiving intratumoral PBS. Three out of the 4 mice were cleared from the tumor thoroughly in 10–25 days after administration of B.F.S. mice receiving intratumoral B.F.S significantly secreted higher interferon γ and lower IL-10 compared with the other groups. Overall, our findings indicated that intratumoral administration of B.F.S effectively inhibited the growth of breast tumors through induction of necrosis and suppressing proliferation and angiogenesis.

The аntitumor effect of 2-[3-(2-chloroethyl)-3-nitrosoureido]-1,3-propanediol (chlonisol) on the growth of spontaneous mammary tumors in HER-2/neu transgenic mice

Background. Current treatment of HER2-positive metastatic breast cancer (BC) is based on the use of anti-HER2 blockers as pathogenic drugs, as well as the search for the optimal combination of anticancer drugs with different mechanisms of action. The potential activity of chlonisol in HER2+ ВС is of great interesting. The aim of the study was to evaluate the antitumor effect of 2-[3-(2-chloroethyl)-3-nitrosouriedo]-1,3-propanediol (chlonisol) on the growth of spontaneous mammary tumors in HER-2/neu transgenic FVB/N mice. Material and Methods. A prospective study used 5-month-old female mice with HER2-positive mammary tumors. Of these animals, ten pairs with almost the same size of tumors were formed (respectively, for the control group and the chlonisol treatment group). Chlonisol was administered at a dose of 20 mg/kg intraperitoneally, once. The animals were followed up for 30 days. Results. In all ten pairs of mice, chlonisol showed a significant antitumor effect, up to a complete temporary regression of the tumor. When summing the comparative results of all ten pairs of animals, the inhibition of tumor growth (ITG) in the chlonisol treatment group was 90-97 % (p&lt;0.0001), and the area under the kinetic curve of tumor growth was 13.6 times less than in the control group (p&lt;0.0001), thus indicating a significant effect. Conclusion. Chlonisol has a high therapeutic activity by inhibiting the growth of spontaneous HER2-positive breast tumors in FVB/N mice.

Toxoplasma gondii gra5 deletion mutant protects hosts against Toxoplasma gondii infection and breast tumors.

Toxoplasma gondii is the causative agent of toxoplasmosis, a zoonotic disease that poses a threat to human health and a considerable loss to livestock farming. At present, clinical therapeutic drugs mainly target T. gondii tachyzoites and fail to eradicate bradyzoites. Developing a safe and effective vaccine against toxoplasmosis is urgent and important. Breast cancer has become a major public health problem and the therapeutic method needs to be further explored. Many similarities exist between the immune responses caused by T. gondii infection and the immunotherapy for cancers. T. gondii dense granule organelles secrete immunogenic dense granule proteins (GRAs). GRA5 is localized to the parasitophorous vacuole membrane in the tachyzoite stage and the cyst wall in the bradyzoite stage. We found that T. gondii ME49 gra5 knockout strain (ME49Δgra5) was avirulent and failed to form cysts but stimulated antibodies, inflammatory cytokines, and leukocytes infiltration in mice. We next investigated the protective efficacy of ME49Δgra5 vaccination against T. gondii infection and tumor development. All the immunized mice survived the challenge infection of either wild-type RH, ME49, VEG tachyzoites, or ME49 cysts. Moreover, ME49Δgra5 tachyzoite inoculation in situ attenuated the growth of murine breast tumor (4T1) in mice and prevented 4T1's lung metastasis. ME49Δgra5 inoculation upregulated the levels of Th1 cytokines and tumor-infiltrating T cells in the tumor microenvironment and triggered anti-tumor responses by increasing the number of natural killer, B, and T cells, macrophages, and dendritic cells in the spleen. Collectively, these results suggested that ME49Δgra5 was a potent live attenuated vaccine against T. gondii infection and breast cancer.

Epigenetic reprogramming of cell cycle genes by ACK1 promotes breast cancer resistance to CDK4/6 inhibitor

Hormone receptor-positive, HER2-negative advanced breast cancers exhibit high sensitivity to CDK4/6 inhibitors such as palbociclib. However, most patients inevitably develop resistance, thus identification of new actionable therapeutic targets to overcome the recurrent disease is an urgent need. Immunohistochemical studies of tissue microarray revealed increased activation of non-receptor tyrosine kinase, ACK1 (also known as TNK2) in most of the breast cancer subtypes, independent of their hormone receptor status. Chromatin immunoprecipitation studies demonstrated that the nuclear target of activated ACK1, pY88-H4 epigenetic marks, were deposited at cell cycle genes, CCNB1, CCNB2 and CDC20, which in turn initiated their efficient transcription. Pharmacological inhibition of ACK1 using its inhibitor, (R)-9b dampened CCNB1, CCNB2 and CDC20 expression, caused G2/M arrest, culminating in regression of palbociclib-resistant breast tumor growth. Further, (R)-9b suppressed expression of CXCR4 receptor, which resulted in significant impairment of metastasis of breast cancer cells to lung. Overall, our pre-clinical data identifies activated ACK1 as an oncogene that epigenetically controls the cell cycle genes governing the G2/M transition in breast cancer cells. ACK1 inhibitor, (R)-9b could be a novel therapeutic option for the breast cancer patients that have developed resistance to CDK4/6 inhibitors.

Autotaxin Inhibition with IOA-289 Decreases Breast Tumor Growth in Mice Whereas Knockout of Autotaxin in Adipocytes Does Not.

Breast cancer cells produce negligible quantities of autotaxin. Instead, previous work indicated that adipocytes in the inflamed adipose tissue adjacent to breast tumors are a major source of autotaxin secretion that drives breast tumor growth, metastasis, and the loss of efficacy for chemotherapy and radiotherapy. To test this hypothesis, we used mice with an adipocyte-specific knock out of autotaxin. The lack of autotaxin secretion from adipocytes failed to decrease the growth of orthotopic E0771 breast tumors in syngeneic C57BL/6 mice and the growth and lung metastasis of spontaneous breast tumors in MMTV-PyMT mice. However, the inhibition of autotaxin with IOA-289 decreased the growth of E0771 tumors, indicating that another source of autotaxin is responsible for tumor growth. Tumor-associated fibroblasts and leukocytes produce the majority of autotoxin transcripts in the E0771 breast tumors, and we hypothesize that they are the main sources of ATX that drive breast tumor growth. Autotaxin inhibition with IOA-289 increased the numbers of CD8α+-T-cells in the tumors. This was accompanied by decreases in the concentrations of CXCL10, CCL2, and CXCL9 in the plasma and LIF, TGFβ1, TGFβ2, and prolactin in the tumors. Bioinformatics analysis of human breast tumor databases showed that autotaxin (ENPP2) is expressed mainly in endothelial cells and fibroblasts. Autotaxin expression correlated significantly with increases in IL-6 cytokine receptor ligand interactions, signaling by LIF, TGFβ, and prolactin. This confirms the relevance of results from autotaxin inhibition in the mouse model. We propose that inhibiting autotaxin activity that is derived from cells presenting breast tumors such as fibroblasts, leukocytes, or endothelial cells changes the tumor micro-environment in such a way as to inhibit tumor growth.

Hybrid biointerface engineering nanoplatform for dual-targeted tumor hypoxia relief and enhanced photodynamic therapy

The clinical application of photodynamic therapy (PDT) is limited by the lack of tumor selectivity of photosensitizer (PS) and the hypoxic tumor microenvironment (TME). To address these limitations of PDT, we developed a hybrid engineered biointerface nanoplatform that integrated anti-epidermal growth factor receptor (EGFR)-aptamer (EApt)-modified liposomes with tumor cell membranes (TMs) to create M/L-EApt. M/L-EApt exhibited enhanced stability and significant dual-targeting ability, enabling selectively accumulate in hypoxic tumor regions after systemic infusion. PHI@M/L-EApt, formed by M/L-EApt loaded with an oxygen carrier perfluorotributylamine (PFTBA) and IR780 (a PS), effectively promoted the therapeutic performance of PDT by reversing the hypoxic TME and increasing the accumulation of IR780 at the tumor sites, resulting in a robust anti-tumor efficacy. In vivo results showed that PHI@M/L-EApt treatment effectively suppressed the growth of triple-negative breast tumors in mice. Our findings demonstrated the synergistic effect of oxygen supply and PDT on tumor treatment using PHI@M/L-EApt. This study presented a biomimetic interface engineering strategy and dual-targeted hybrid nanoplatform for relieving hypoxic TME and potentially facilitating the clinical application of PDT.

CHMP4A stimulates CD8+ T-lymphocyte infiltration and inhibits breast tumor growth via the LSD1/IFNβ axis.

CD8+ T lymphocyte-mediated immunity strategies have represented attractive weapons against breast cancer (BC) recently. However, the mechanisms underlying CD8+ T-lymphocyte infiltration still remain obscure. Here, using bioinformatics analysis, we identified four hub prognostic genes related to CD8+ T-lymphocyte infiltration (CHMP4A, CXCL9, GRHL2, and RPS29), among which CHMP4A was the most significant gene. High CHMP4A mRNA expression was significantly associated with longer overall survival (OS) in BC patients. Functional experiments showed that CHMP4A had the ability to promote CD8+ T-lymphocyte recruitment and infiltration and suppressed BC growth in vitro and in vivo. Mechanistically, CHMP4A stimulates CD8+ T-lymphocyte infiltration by downregulating LSD1 expression, leading to HERV dsRNA accumulation, and promoting IFNβ and its downstream chemokine production. Collectively, CHMP4A is not only a novel positive predictor for prognosis in BC but also a stimulator of CD8+ T-lymphocyte infiltration regulated by the LSD1/IFNβ pathway. This study suggests that CHMP4A may be a novel target for improving the effectiveness of immunotherapy in patients with BC.

Breast Cancer Immunity: It is TIME for the Next Chapter.

Our ability to interrogate the tumor immune microenvironment (TIME) at an ever-increasing granularity has uncovered critical determinants of disease progression. Not only do we now have a better understanding of the immune response in breast cancer, but it is becoming possible to leverage key mechanisms to effectively combat this disease. Almost every component of the immune system plays a role in enabling or inhibiting breast tumor growth. Building on early seminal work showing the involvement of T cells and macrophages in controlling breast cancer progression and metastasis, single-cell genomics and spatial proteomics approaches have recently expanded our view of the TIME. In this article, we provide a detailed description of the immune response against breast cancer and examine its heterogeneity in disease subtypes. We discuss preclinical models that enable dissecting the mechanisms responsible for tumor clearance or immune evasion and draw parallels and distinctions between human disease and murine counterparts. Last, as the cancer immunology field is moving toward the analysis of the TIME at the cellular and spatial levels, we highlight key studies that revealed previously unappreciated complexity in breast cancer using these technologies. Taken together, this article summarizes what is known in breast cancer immunology through the lens of translational research and identifies future directions to improve clinical outcomes.

Hinokitiol-iron complex is a ferroptosis inducer to inhibit triple-negative breast tumor growth

BackgroundFerroptosis is a unique cell death, dependent on iron and phospholipid peroxidation, involved in massive processes of physiopathology. Tremendous attention has been caught in oncology, particularly for those therapy-resistant cancers in the mesenchymal state prone to metastasis due to their exquisite vulnerability to ferroptosis. Therefore, a therapeutical ferroptosis inducer is now underway to be exploited.ResultsA natural compound, hinokitiol (hino), has been considered to be an iron chelator. We have a novel finding that hino complexed with iron to form Fe(hino)3 can function as a ferroptosis inducer in vitro. The efficiency, compared with the same concentration of iron, increases nearly 1000 folds. Other iron chelators, ferroptosis inhibitors, or antioxidants can inhibit Fe(hino)3-induced ferroptosis. The complex Fe(hino)3 efficacy is further confirmed in orthotopic triple-negative breast cancer (TNBC) tumor models that Fe(hino)3 significantly boosted lipid peroxidation to induce ferroptosis and significantly reduced the sizes of TNBC cell-derived tumors. The drug’s safety was also evaluated, and no detrimental side effects were found with the tested dosage.ConclusionsWhen entering cells, the chelated iron by hinokitiol as a complex Fe(hino)3 is proposed to be redox-active to vigorously promote the production of free radicals via the Fenton reaction. Thus, Fe(hino)3 is a ferroptosis inducer and, therapeutically, exhibits anti-TNBC activity.

Effective therapy with Bismuth-212 labeled macroaggregated albumin in orthotopic mouse breast tumor models.

Intravascularly administered radiation therapy using beta (β-)-emitting radioisotopes has relied on either intravenously injected radiolabeled peptides that target cancer or radiolabeled microspheres that are trapped in the tumor following intra-arterial delivery. More recently, targeted intravenous radiopeptide therapies have explored the use of alpha (α)-particle emitting radioisotopes, but microspheres radiolabeled with α-particle emitters have not yet been studied. Here, FDA-approved macroaggregated albumin (MAA) particles were radiolabeled with Bismuth-212 (Bi-212-MAA) and evaluated using clonogenic and survival assays in vitro and using immune-competent mouse models of breast cancer. The in vivo biodistribution of Bi-212-MAA was investigated in Balb/c and C57BL/6 mice with 4T1 and EO771 orthotopic breast tumors, respectively. The same orthotopic breast cancer models were used to evaluate the treatment efficacy of Bi-212-MAA. Our results showed that macroaggregated albumin can be stably radiolabeled with Bi-212 and that Bi-212-MAA can deliver significant radiation therapy to reduce the growth and clonogenic potential of 4T1 and EO771 cells in vitro. Additionally, Bi-212-MAA treatment upregulated γH2AX and cleaved Caspase-3 expression in 4T1 cells. Biodistribution analyses showed 87-93% of the Bi-212-MAA remained in 4T1 and EO771 tumors 2 and 4h after injection. Following single-tumor treatments with Bi-212-MAA there was a significant reduction in the growth of both 4T1 and EO771 breast tumors over the 18-day monitoring period. Overall, these findings showed that Bi-212-MAA was stably radiolabeled and inhibited breast cancer growth. Bi-212-MAA is an exciting platform to study α-particle therapy and will be easily translatable to larger animal models and human clinical trials.