Mammary carcinoma: Comparative oncology between small animals and humans-New therapeutic tools.

The poor outcomes associated with mammary carcinomas (MCs) in dogs and cats in terms of locoregional recurrence, distant metastasis and survival, highlight the need for better management of mammary cancers in small animals. By contrast, the outcomes of women with breast cancer (BC) have dramatically improved during the last 10 years, notably thanks to new therapeutic strategies. The aim of this article was to imagine what could be the future of therapy for dogs and cats with MCs if it became inspired from current practices in human BC. This article focuses on the importance of taking into account cancer stage and cancer subtypes in therapeutic plans, on locoregional treatments (surgery, radiation therapy), new developments in endocrine therapy, chemotherapy, PARP inhibitors and immunotherapy. Ideally, multimodal treatment regimens would be chosen according to cancer stage and cancer subtypes, and according to predictive factors that are still to be defined.

Targeted TLR9 Agonist Elicits Effective Antitumor Immunity against Spontaneously Arising Breast Tumors.

Spontaneous tumors that arise in genetically engineered mice recapitulate the natural tumor microenvironment and tumor-immune coevolution observed in human cancers, providing a more physiologically relevant preclinical model relative to implanted tumors. Similar to many cancer patients, oncogene-driven spontaneous tumors are often resistant to immunotherapy, and thus novel agents that can effectively promote antitumor immunity against these aggressive cancers show considerable promise for clinical translation, and their mechanistic assessment can broaden our understanding of tumor immunology. In this study, we performed extensive immune profiling experiments to investigate how tumor-targeted TLR9 stimulation remodels the microenvironment of spontaneously arising tumors during an effective antitumor immune response. To model the clinical scenario of multiple tumor sites, we used MMTV-PyMT transgenic mice, which spontaneously develop heterogeneous breast tumors throughout their 10 mammary glands. We found that i.v. administration of a tumor-targeting TLR9 agonist, referred to as PIP-CpG, induced a systemic T cell-mediated immune response that not only promoted regression of existing mammary tumors, but also elicited immune memory capable of delaying growth of independent newly arising tumors. Within the tumor microenvironment, PIP-CpG therapy initiated an inflammatory cascade that dramatically amplified chemokine and cytokine production, prompted robust infiltration and expansion of innate and adaptive immune cells, and led to diverse and unexpected changes in immune phenotypes. This study demonstrates that effective systemic treatment of an autochthonous multisite tumor model can be achieved using a tumor-targeted immunostimulant and provides immunological insights that will inform future therapeutic strategies.

Retarding breast tumor growth with nanoparticle-facilitated intravenous delivery of BRCA1 and BRCA2 tumor suppressor genes.

Gene augmentation therapy entails replacement of the abnormal tumor suppressor genes in cancer cells. In this study, we performed gene augmentation for BRCA1/2 tumor suppressors in order to retard tumor development in breast cancer mouse model. We formulated inorganic carbonate apatite (CA) nanoparticles (NPs) to carry and deliver the purified BRCA1/2 gene- bearing plasmid DNA both in vitro and in vivo. The outcome of BRCA1/2 plasmid-loaded NPs delivery on cellular viability of three breast cancer cell lines such as MCF-7, MDA-MB-231 and 4T1 were evaluated by MTT assay. The result in MCF-7 cell line exhibited that transfection of BRCA 1/2 plasmids with CA NPs significantly reduced cancer cell growth in comparison to control group. Moreover, we noticed a likely pattern of cellular cytotoxicity in 4T1 murine cancer cell line. Following transfection with BRCA1 plasmid-loaded NPs, and Western blot analysis, a notable reduction in the phospho-MAPK protein of MAPK signaling pathway was detected, revealing reduced growth signal. Furthermore, in vivo study in 4T1 induced breast cancer mouse model showed that the tumor growth rate and final volume were decreased significantly in the mouse group treated intravenously with BRCA1 + NPs and BRCA2 + NPs formulations. Our results established that BRCA1/2 plasmids incorporated into CA NPs mitigated breast tumor growth, signifying their application in the therapy for breast cancer.

Iridium Tungstate Nanozyme-Mediated Hypoxic Regulation and Anti-inflammation for Duplex Imaging Guided Photothermal Therapy of Metastatic Breast Tumors.

Metastasis of breast cancer is key to poor prognosis and high mortality. However, the excess reactive oxygen species (ROS) and inflammatory response induced by photothermal therapy (PTT) further aggravate tumor metastasis. Meanwhile, the hypoxic tumor microenvironment promotes tumor cells to metastasize to distant organs. Herein, the intrinsic limitations of PTT for metastatic tumor have been addressed by fabricating polyethylene glycol modified iridium tungstate (IrWOx-PEG) nanoparticles. The as-designed IrWOx-PEG nanoparticles displayed good photothermal (PT) conversion ability for duplex photoacoustic/PT imaging guided PTT and multienzyme mimetic feature for broad-spectrum ROS scavenging. On the one hand, IrWOx-PEG effectively removed excess ROS generated during PTT and reduced inflammation. On the other hand, owing to the catalase-like activity, it preferentially triggered the catalytic production of oxygen by decomposing ROS, leading to relieving of the hypoxic microenvironment. Hence, under bimodal imaging guidance, IrWOx-PEG induced PTT completely eliminated in situ breast cancer in 4T1 tumor-bearing mice with no observable system toxicity, as well as further restricting tumor metastasis to other vital organs (lungs) by ROS scavenging, anti-inflammation, and regulating hypoxic microenvironment. We anticipate that this work will lead to new treatment strategies for other metastatic cancers.

Correlation of Cytokine Content in the Lymph with the Morphological Parameters of the Mesenteric Lymph Nodes in Adjuvant Therapy of Experimental Breast Cancer with the Use of Fragmented Human DNA.

We studied the relationship between the level of cytokines in the lymph of the thoracic duct and the morphometric parameters of the mesenteric lymph nodes after surgical treatment of breast cancer, chemotherapy, and administration of fragmented (double-stranded, dsDNA) human DNA. In comparison with surgical treatment and with chemotherapy alone, administration of a human dsDNA has a stimulating effect on the T-cell link of the immune response. In the paracortical zone, the relationship between the chemokine MCP-1 and increased content of small lymphocytes in this zone was revealed. Interrelations of IL-2 cytokines with small lymphocytes and of IL-4 with medium lymphocytes were revealed in germinal centers. We also observed interrelations of IL-7 with small lymphocytes and IL-4 with macrophages in the medullary cords, chemokine MIP-1α with immature and mature plasma cells (the number of these cells is reduced), and of MCP-1 with immunoblasts (the number of which is also reduced) in the medullary sinuses.

Immunoprotective effect of an in silico designed multiepitope cancer vaccine with BORIS cancer-testis antigen target in a murine mammary carcinoma model.

In our previous study, immunoinformatic tools were used to design a novel multiepitope cancer vaccine based on the most immunodominant regions of BORIS cancer-testis antigen. The final vaccine construct was an immunogenic, non-allergenic, and stable protein consisted of multiple cytotoxic T lymphocytes epitopes, IFN-γ inducing epitopes, and B cell epitopes according to bioinformatic analyzes. Herein, the DNA sequence of the final vaccine construct was placed into the pcDNA3.1 vector as a DNA vaccine (pcDNA3.1-VAC). Also, the recombinant multiepitope peptide vaccine (MPV) was produced by a transfected BL21 E. coli strain using a recombinant pET-28a vector and then, purified and screened by Fast protein liquid chromatography technique (FPLC) and Western blot, respectively. The anti-tumor effects of prophylactic co-immunization with these DNA and protein cancer vaccines were evaluated in the metastatic non-immunogenic 4T1 mammary carcinoma in BALB/c mice. Co-immunization with the pcDNA3.1-VAC and MPV significantly (P < 0.001) increased the serum levels of the MPV-specific IgG total, IgG2a, and IgG1. The splenocytes of co-immunized mice exhibited a significantly higher efficacy to produce interleukin-4 and interferon-γ and proliferation in response to MPV in comparison with the control. The prophylactic co-immunization regime caused significant breast tumors' growth inhibition, tumors' weight decrease, inhibition of metastasis formation, and enlarging tumor-bearing mice survival time, without any considerable side effects. Taking together, this cancer vaccine can evoke strong immune response against breast tumor and inhibits its growth and metastasis.

131I-Labeled gold nanoframeworks for radiotherapy-combined second near-infrared photothermal therapy of cancer.

Photothermal therapy (PTT) has shown great promise for cancer treatment via light-triggered heat generation, while the anticancer efficacy of sole PTT is often limited. In this study, we report the use of radionuclide 131I-labeled gold nanoframeworks (131I-AuNFs) for radiotherapy-combined second near-infrared (NIR-II) PTT of breast cancer. AuNFs synthesized via a simple reduction approach are surface functionalized with polydopamine and poly(ethylene glycol), followed by labeling with 131I. The formed 131I-AuNFs with a high photothermal conversion efficacy and stable radioactivity can effectively accumulate into subcutaneous 4T1 mouse models as confirmed by in vivo single photon emission computed tomography (SPECT) imaging. Upon 1064 nm laser irradiation of tumors, local heat is generated for NIR-II PTT, which combines with radiotherapy to achieve a much higher therapeutic efficacy relative to sole treatment. As such, 131I-AuNFs-mediated radiotherapy-combined NIR-II PTT results in the effective inhibition of the growth of subcutaneous tumors. This study thus provides a facile nanoplatform for effective combination cancer therapy.

Canine Natural Killer Cell-Derived Exosomes Exhibit Antitumor Activity in a Mouse Model of Canine Mammary Tumor.

Natural killer (NK) cells are key immune cells engaged in fighting infection and malignant transformation. In this study, we found that canine NK cell-derived exosomes (NK-exosomes) separated from activated cytotoxic NK cell supernatants express specific markers including CD63, CD81, Alix, HSP70, TSG101, Perforin 1, and Granzyme B. We examined the antitumor effects of NK-exosomes in an experimental murine mammary tumor model using REM134 canine mammary carcinoma cell line. We observed changes in tumor size, tumor initiation, progression, and recurrence-related markers in the control, tumor group, and NK-exosome-treated tumor group. We found that the tumor size in the NK-exosome-treated tumor group decreased compared with that of the tumor group in the REM134-driven tumorigenic mouse model. We observed significant changes including the expression of tumorigenesis-related markers, such as B cell-specific Moloney murine leukemia virus insertion site 1 (Bmi-1), vascular endothelial growth factor (VEGF), matrix metallopeptidase-3 (MMP-3), interleukin-1ß (IL-1ß), IL-6, tumor necrosis factor-α (TNF-α), multidrug resistance protein (MDR), tumor suppressor protein p53 (p53), proliferating cell nuclear antigen (PCNA), and the apoptotic markers, B cell lymphoma-2 associated X (Bax) and B cell lymphoma-extra large (Bcl-xL) belonging to the Bcl-2 family, in the tumor group compared with those in the control group. The expression of CD133, a potent cancer stem cell marker, was significantly higher than that of the control. By contrast, the NK-exosome-treated tumor group exhibited a significant reduction in Bmi-1, MMP-3, IL-1ß, IL-6, TNF-α, Bax, Bcl-xL, and PCNA expression compared with that in the tumor group. Furthermore, the expression of CD133, which mediates tumorigenesis, was significantly decreased in the NK-exosome-treated tumor group compared with that in the tumor group. These findings indicate that canine NK-exosomes represent a promising therapeutic tool against canine solid tumors, including mammary carcinoma.

Multimodal Intralesional Therapy for Reshaping the Myeloid Compartment of Tumors Resistant to Anti-PD-L1 Therapy via IRF8 Expression.

Intralesional therapy is a promising approach for remodeling the immunosuppressive tumor microenvironment while minimizing systemic toxicities. A combinatorial in situ immunomodulation (ISIM) regimen with intratumoral administration of Fms-like tyrosine kinase 3 ligand (Flt3L), local irradiation, and TLR3/CD40 stimulation induces and activates conventional type 1 dendritic cells in the tumor microenvironment and elicits de novo adaptive T cell immunity in poorly T cell-inflamed tumors. However, the impact of ISIM on myeloid-derived suppressor cells (MDSCs), which may promote treatment resistance, remains unknown. In this study, we examined changes in the frequencies and heterogeneity of CD11b+Ly-6CloLy-6G+ polymorphonuclear (PMN)-MDSCs and CD11b+Ly-6ChiLy-6G- monocytic (M)-MDSCs in ISIM-treated tumors using mouse models of triple-negative breast cancer. We found that ISIM treatment decreased intratumoral PMN-MDSCs, but not M-MDSCs. Although the frequency of M-MDSCs remained unchanged, ISIM caused a substantial reduction of CX3CR1+ M-MDSCs that express F4/80. Importantly, these ISIM-induced changes in tumor-residing MDSCs were not observed in Batf3-/- mice. ISIM upregulated PD-L1 expression in both M-MDSCs and PMN-MDSCs and synergized with anti-PD-L1 therapy. Furthermore, ISIM increased the expression of IFN regulatory factor 8 (IRF8) in myeloid cells, a known negative regulator of MDSCs, indicating a potential mechanism by which ISIM decreases PMN-MDSC levels. Accordingly, ISIM-mediated reduction of PMN-MDSCs was not observed in mice with conditional deletion of IRF8 in myeloid cells. Altogether, these findings suggest that ISIM holds promise as a multimodal intralesional therapy to alter both lymphoid and myeloid compartments of highly aggressive poorly T cell-inflamed, myeloid-enriched tumors resistant to anti-PD-L1 therapy.

Evaluation of the oncolytic property of recombinant Newcastle disease virus strain R2B in 4T1 and B16-F10 cells in-vitro.

Recombinant Newcastle disease virus vectors have gained a lot of interest for its oncolytic virus therapy and cancer immune therapeutic properties due to its selective replication to high titers in cancer cells. The aim of this study was to find out the oncolytic effects of mesogenic recombinant NDV strain R2B-GFP on murine mammary tumor cell line 4T1 and murine melanoma cell line B16-F10. The anti-tumor effects of R2B-GFP virus were studied via expression of virus transgene GFP in cancer cells, evaluating its cytotoxicity and cell migration efficacies by MTT and wound healing assays respectively. In addition, the underlying apoptotic mechanism of R2B-GFP virus was estimated by TUNEL assay, colorimetric estimation of Caspase-3, 8 and 9 and the estimation of Bax to Bcl-2 ratio. The results showed a significant decrease in viability of both 4T1 and B16-F10 cells infected with R2B-GFP virus at 0.1 and 1 MOI. R2B-GFP virus could significantly induce apoptosis in the 4T1 and B16-F10 cells as compared to the uninfected control. Further, a flow cytometry analysis on apoptotic cells percentage and mitochondria membrane permeability test was also studied in R2B-GFP virus treated 4T1 and B16-F10 cell lines. The R2B-GFP virus caused an increase in loss of mitochondrial membrane permeability in both 4T1 and B16-F10 cells indicating the involvement of mitochondrial regulated cell death. Thus, the recombinant virus R2B-GFP virus proved to be a valid candidate for oncolytic viral therapy in 4T1 and B16-F10 cells.

Cytotoxic T cells response with decreased CD4/CD8 ratio during mammary tumors inhibition in rats induced by non-contact electric fields.

Background: Breast cancer is the most common cancer in women worldwide and is the leading cause of death in women with cancer. One novel therapy used for breast cancer treatment is non-contact electric fields called electro-capacitive cancer therapy (ECCT) with intermediate frequency (100 kHz) and low intensity (18 Vpp). The objective of this study was to examine the effect of ECCT on mammary tumors growth in rats and observing the immune responses that play a role in fighting the tumor. Methods: Female SD rats were used and divided into four groups, namely control (NINT), placebo (NIT), non- therapy (INT), and therapy (IT) groups with 6 biological replicates in each group. Rats in INT and IT groups were treated with 7,12-dimethylbenz[a]anthracene for mammary tumor induction. Only rats in NIT and IT groups were exposed to ECCT individually for 10 hours per day for 21 days. The size of all tumors was measured with a digital caliper. The distributions of PCNA, ErbB2, caspase-3, CD68, CD4 and CD8-positive cells were observed with immunohistochemistry and scoring with ImageJ. Results: The growth rate of mammary tumors in IT group was significantly lower (p<0.05) than that in the INT group. The number of mitotic figures and the percentage of PCNA, caspase-3, and CD68- positive cells in IT group were significantly lower (p<0.05) than those in INT group. Conversely, the percentage of CD8-positive T cells in IT group was significantly higher (p<0.05) than that in INT group. Moreover, the CD4/CD8 ratio in IT group was decreased. Some tumor tissues were blackened and detached from the surrounding tissue, resulting in an open wound which then healed up upon exposure. Conclusions: Non-contact electric fields exposure showed inhibition on mammary tumor growth in rats while inducing CD8+ T cells that lead to tumor cells death and potentially helps wound healing.

The implication of autoantibodies in early diagnosis and monitoring of plasmonic photothermal therapy in the treatment of feline mammary carcinoma.

Feline mammary carcinoma (FMC) shows great similarities to human breast cancer in the cellular and molecular levels. So, in cats as in humans, the role of immune responses is indicated to detect and follow up the development of tumors. As a new breast cancer therapeutic approach, Plasmonic Photothermal Therapy (PPTT) is an effective localized treatment for canine and feline mammary-carcinoma. Its systemic effect has not been inquired yet and needs many studies to hypothesis how the PPTT eradicates tumor cells. In this study, it is the first time to detect (P53, PCNA, MUC-1, and C-MYC) feline autoantibodies (AAbs), study the relationship between PCNA AAbs and mammary-tumors, and investigate the effect of PPTT on the humoral immune response of cats with mammary-carcinoma through detection of AAbs level before, during, and after the treatment. The four-AAbs panel was evaluated in serum of normal and clinically diagnosed cats with mammary tumors using Enzyme-Linked Immunosorbent Assay. The panel showed 100% specificity and 93.7% sensitivity to mammary tumors. The panel was evaluated in PPTT monotherapy, mastectomy monotherapy, and combination therapy. PPTT monotherapy decreased AAbs level significantly while mastectomy monotherapy and combination therapy had a nonsignificant effect on AAbs level.

Oncolytic effect of Newcastle disease virus is attributed to interferon regulation in canine mammary cancer cell lines.

Canine mammary carcinoma (CMC) is one of the major health threats in dogs. The oncolytic virotherapy is a promising strategy to treat canine as well as human cancer patients with non-pathogenic replicating viruses. Here, we evaluated the antitumor activity of one lentogenic, non-lytic Newcastle disease virus (NDV) LaSota strain expressing GFP (NDV-GFP) on five different CMCs and one non-tumorigenic cell line, regarding cell viability, cell death, selectivity index, morphology, global and target gene expression analysis. As evidenced by the selectivity index, all CMC cell lines were more susceptible to NDV-GFP in comparison with the non-tumorigenic cells (~3.1× to ~78.7×). In addition, the oncolytic effect of NDV-GFP was more evident in more malignant CMC cells. Also, we observed an inverse association of the IFN pathway expression and the susceptibility to NDV. The downregulated genes in NDV-GFP-sensitive cells were functionally enriched for antiviral mechanisms by interferon and immune system pathways, demonstrating that these mechanisms are the most prominent for oncolysis by NDV. To our knowledge, this is the first description of oncolysis by an NDV strain in canine mammary cancer cells. We also demonstrated specific molecular pathways related to NDV susceptibility in these cancer cells, opening the possibility to use NDV as a therapeutic-targeted option for more malignant CMCs. Therefore, these results urge for more studies using oncolytic NDVs, especially considering genetic editing to improve efficacy in dogs.

Metabolic modulation by CDK4/6 inhibitor promotes chemokine-mediated recruitment of T cells into mammary tumors.

Inhibitors of cyclin-dependent kinases 4 and 6 (CDK4/6i) delay progression of metastatic breast cancer. However, complete responses are uncommon and tumors eventually relapse. Here, we show that CDK4/6i can enhance efficacy of T cell-based therapies, such as adoptive T cell transfer or T cell-activating antibodies anti-OX40/anti-4-1BB, in murine breast cancer models. This effect is driven by the induction of chemokines CCL5, CXCL9, and CXCL10 in CDK4/6i-treated tumor cells facilitating recruitment of activated CD8+ T cells, but not Tregs, into the tumor. Mechanistically, chemokine induction is associated with metabolic stress that CDK4/6i treatment induces in breast cancer cells. Despite the cell cycle arrest, CDK4/6i-treated cells retain high metabolic activity driven by deregulated PI3K/mTOR pathway. This causes cell hypertrophy and increases mitochondrial content/activity associated with oxidative stress and inflammatory stress response. Our findings uncover a link between tumor metabolic vulnerabilities and anti-tumor immunity and support further development of CDK4/6i and immunotherapy combinations.

Phase-Transformation Nanoparticle-Mediated Sonodynamic Therapy: An Effective Modality to Enhance Anti-Tumor Immune Response by Inducing Immunogenic Cell Death in Breast Cancer.

PURPOSE: Immunologically quiescent of breast cancer cells has been recognized as the key impediment for the breast cancer immunotherapy. In this study, we aimed to investigate the role of nanoparticle-mediated sonodynamic therapy (SDT) in promoting anti-tumor immune of breast cancer cells and its potential immune mechanisms. MATERIALS AND METHODS: The phase-transformation nanoparticles (LIP-PFH nanoparticles) were in-house prepared and its physiochemical characters were detected. The CCK-8 assay, apoptosis analysis and Balb/c tumor model establishment were used to explore the anti-tumor effect of LIP-PFH nanoparticles triggered by low-intensity focused ultrasound (LIFU) both in vitro and in vivo. Flow cytometry and immunohistochemistry of CD4+T, CD8+T, CD8+PD-1+T in blood, spleen and tumor tissue were performed to represent the change of immune response. Detection of immunogenic cell death (ICD) markers was examined to study the potential mechanisms. RESULTS: LIP-PFH nanoparticles triggered by LIFU could inhibit the proliferation and promote the apoptosis of 4T1 cells both in vitro and in vivo. CD4+T and CD8+T cell subsets were significantly increased in blood, spleen and tumor tissue, meanwhile CD8+PD-1+T cells were reduced, indicating enhancement of anti-tumor immune response of breast cancer cells in the nanoparticle-mediated SDT group. Detection of ICD markers (ATP, high-mobility group box B1, and calreticulin) and flow cytometric analysis of dendritic cell (DC) maturity further showed that the nanoparticle-mediated SDT can promote DC maturation to increase the proportion of cytotoxic T cells by inducing ICD of breast cancer cells. CONCLUSION: The therapy of nanoparticles-mediated SDT can effectively enhance anti-tumor immune response of breast cancer.

Transient Vasodilation in Mouse 4T1 Tumors after Intragastric and Intravenous Administration of Gold Nanoparticles.

Gold nanoparticles (AuNPs) are foreseen as a promising tool in nanomedicine, both as drug carriers and radiosensitizers. They have been also proposed as a potential anticancer drug due to the anti-angiogenic effect in tumor tissue. In this work we investigated the effect of citrate-coated AuNPs of nominal diameter 20 nm on the growth and metastatic potential of 4T1 cells originated from a mouse mammary gland tumor inoculated into the mammary fat pad of Balb/ccmdb mice. To evaluate whether AuNPs can prevent the tumor growth, one group of inoculated mice was intragastrically (i.g.) administered with 1 mg/kg of AuNPs daily from day 1 to day 14 after cancer cell implantation. To evaluate whether AuNPs can attenuate the tumor growth, the second group was intravenously (i.v.) administered with 1 or 5 mg/kg of AuNPs, twice on day 5 and day 14 after inoculation. We did not observe any anticancer activity of i.v. nor i.g. administered AuNPs, as they did not affect neither the primary tumor growth rate nor the number of lung metastases. Unexpectedly, both AuNP treatment regimens caused a marked vasodilating effect in the tumor tissue. As no change of potential angiogenic genes (Fgf2, Vegfa) nor inducible nitric oxygenase (Nos2) was observed, we proposed that the vasodilation was caused by AuNP-dependent decomposition of nitrosothiols and direct release of nitric oxide in the tumor tissue.

Urchin-Shaped Metal Organic/Hydrogen-Bonded Framework Nanocomposite as a Multifunctional Nanoreactor for Catalysis-Enhanced Synergetic Therapy.

Ultrasound (US)-induced sonodynamic therapy (SDT) is an efficient and precise method against tumor, and the integration of multiple cancer therapies has been proved as a promising strategy for better therapeutic effects. Herein, for the first time, a multifunctional nanoreactor has been fabricated by integrating Fe-MIL-88B-NH2, PFC-1, and glucose oxidase (GOx) to form urchin-like Fe-MIL-88B-NH2@PFC-1-GOx (MPG) nanoparticles as Fenton's reagent, a sonosensitizer, and a tumor microenvironment (TME) modulator. In detail, MPG can generate •OH for chemodynamic therapy (CDT) and deplete glutathione (GSH) to alleviate the antioxidant ability of cancer cells. Moreover, catalase (CAT)-like MPG can react with H2O2 to generate O2 for relieving hypoxia in TME, enhancing GOx-catalyzed glucose oxidation to produce H2O2 and gluconic acid. Then, the regenerated H2O2 can promote the Fenton reaction to achieve GOx catalysis-enhanced CDT. Owing to its large π-electron conjugated system, MPG also serves as an ideal sonosensitizer, realizing a burst generation of 1O2 under US irradiation for efficient SDT. Therefore, the tumor treatment will be notably enhanced by MPG-based synergetic CDT/SDT/starvation therapy via a series of cascade reactions. Overall, this work develops a versatile nanoreactor with improved tumor treatment effectiveness and broadens the application prospects of porous materials in the field of biomedical research.

Identification of oncolytic vaccinia restriction factors in canine high-grade mammary tumor cells using single-cell transcriptomics.

Mammary carcinoma, including triple-negative breast carcinomas (TNBC) are tumor-types for which human and canine pathologies are closely related at the molecular level. The efficacy of an oncolytic vaccinia virus (VV) was compared in low-passage primary carcinoma cells from TNBC versus non-TNBC. Non-TNBC cells were 28 fold more sensitive to VV than TNBC cells in which VV replication is impaired. Single-cell RNA-seq performed on two different TNBC cell samples, infected or not with VV, highlighted three distinct populations: naïve cells, bystander cells, defined as cells exposed to the virus but not infected and infected cells. The transcriptomes of these three populations showed striking variations in the modulation of pathways regulated by cytokines and growth factors. We hypothesized that the pool of genes expressed in the bystander populations was enriched in antiviral genes. Bioinformatic analysis suggested that the reduced activity of the virus was associated with a higher mesenchymal status of the cells. In addition, we demonstrated experimentally that high expression of one gene, DDIT4, is detrimental to VV production. Considering that DDIT4 is associated with a poor prognosis in various cancers including TNBC, our data highlight DDIT4 as a candidate resistance marker for oncolytic poxvirus therapy. This information could be used to design new generations of oncolytic poxviruses. Beyond the field of gene therapy, this study demonstrates that single-cell transcriptomics can be used to identify cellular factors influencing viral replication.

RAD51AP1 Deficiency Reduces Tumor Growth by Targeting Stem Cell Self-Renewal.

RAD51-associated protein 1 (RAD51AP1) plays an integral role in homologous recombination by activating RAD51 recombinase. Homologous recombination is essential for preserving genome integrity and RAD51AP1 is critical for D-loop formation, a key step in homologous recombination. Although RAD51AP1 is involved in maintaining genomic stability, recent studies have shown that RAD51AP1 expression is significantly upregulated in human cancers. However, the functional role of RAD51AP1 in tumor growth and the underlying molecular mechanism(s) by which RAD51AP1 regulates tumorigenesis have not been fully understood. Here, we use Rad51ap1-knockout mice in genetically engineered mouse models of breast cancer to unravel the role of RAD51AP1 in tumor growth and metastasis. RAD51AP1 gene transcript was increased in both luminal estrogen receptor-positive breast cancer and basal triple-negative breast cancer, which is associated with poor prognosis. Conversely, knockdown of RAD51AP1 (RADP51AP1 KD) in breast cancer cell lines reduced tumor growth. Rad51ap1-deficient mice were protected from oncogene-driven spontaneous mouse mammary tumor growth and associated lung metastasis. In vivo, limiting dilution studies provided evidence that Rad51ap1 plays a critical role in breast cancer stem cell (BCSC) self-renewal. RAD51AP1 KD improved chemotherapy and radiotherapy response by inhibiting BCSC self-renewal and associated pluripotency. Overall, our study provides genetic and biochemical evidences that RAD51AP1 is critical for tumor growth and metastasis by increasing BCSC self-renewal and may serve as a novel target for chemotherapy- and radiotherapy-resistant breast cancer. SIGNIFICANCE: This study provides in vivo evidence that RAD51AP1 plays a critical role in breast cancer growth and metastasis by regulating breast cancer stem cell self-renewal.

Breast cancer animal models and applications.

Breast cancer is the most common malignancy in women. Basic and translational breast cancer research relies heavily on experimental animal models. Ideally, such models for breast cancer should have commonality with human breast cancer in terms of tumor etiology, biological behavior, pathology, and response to therapeutics. This review introduces current progress in different breast cancer experimental animal models and analyzes their characteristics, advantages, disadvantages, and potential applications. Finally, we propose future research directions for breast cancer animal models.