Orthotopic Breast Cancer Model Research Articles

Tumor cell death in orthotopic breast cancer model by NanoALA: a novel perspective on photodynamic therapy in oncology.

Aim: Nano-5-aminolevulic acid (NanoALA)-mediated photodynamic therapy (PDT), an oil-in-water polymeric nanoemulsion of ALA, was evaluated in a murine model of breast cancer. Materials & methods: Analysis of ALA-derived protoporphyrin IX production and acute toxicity test, biocompatibility and treatment efficacy, and long-term effect of NanoALA-PDT on tumor progression were performed. Results: The nanoformulation favored the prodrug uptake by tumor cells in a shorter time (1.5h). As a result, the adverse effects were negligible and the response rates for primary mammary tumor control were significantly improved. Tumor progression was slower after NanoALA-PDT treatment, providing longer survival. Conclusion: NanoALA is a good proactive drug candidate for PDT against cancer potentially applied as adjuvant/neoadjuvant intervention strategy for breast cancer.

Abstract B96: Pharmacodynamic studies of SB 11285, a systemically bioavailable STING agonist in orthotopic tumor models

Abstract Background: The activation of innate and adaptive immunity via Stimulator of Interferon Genes (STING) signaling is a potentially transformative immunotherapeutic strategy in cancer. We have previously reported that SB 11285 is a novel and highly potent STING agonist that can be delivered by intravenous, intraperitoneal and intratumoral routes. We report here the antitumor and pharmacodynamic studies of SB 11285 in multiple orthotopic and subcutaneous syngeneic mouse tumor models. Methods: (1) Orthotopic NBT-II syngeneic rat bladder model: Rat bladder tumor cells were surgically implanted in the bladder wall of rats (n =10). After 6 days, SB 11285 was administered by i.v. @ 0.5, 1.5, and 3mg/kg on days 1, 5, 9,1 3, 17, 21, 25 and 31. Groups of rats treated with docetaxel at 7.5mg/kg i.v. and saline were used as positive and negative controls, respectively. At the end of dosing period, the bladders were harvested and evaluated by measurement of bladder weight and gross pathology. (2) Pharmacodynamic (PD) studies: Syngeneic mouse subcutaneous CT26 colon carcinoma and orthotopic 4T1 breast cancer models were used. In the CT26 model, when mean tumor volume (MTV) reached 125mm3, SB 11285 was administered at 3mg/kg i.v on days 1 and 5. In the orthotopic 4T1 model, SB 11285 was administered i.p. @ 10mg/kg on days 5, 7, 9, 11, 13, 17 and 19. Blood, lymph nodes, spleen and tumor were harvested and evaluated for (i) cytokine analysis by multiplexing assays and (ii) enumeration of CD4+, CD8+, Tregs, macrophages and MDSCs in blood, lymph nodes, spleen and tumor. Results: (1) In the orthotopic NBT-II rat bladder study, animals that received SB 11285 in all doses remained tumor-free based upon gross pathology and bladder weight measurements. SB 11285 was shown to be well tolerated and safe. (2) In both the 4T1 and CT26 PD studies, cytokine analysis of blood and tissues showed strong induction of type I interferon signature without significant systemic inflammatory response. Flow cytometric analysis of blood, lymph nodes, spleen and tumor revealed significant increase in macrophage & CD8+ T-cell infiltration and decrease in Tregs & CD4+ T-cell infiltration. Conclusion: SB 11285 showed potent antitumoral activity in multiple orthotopic and subcutaneous models that correlated with antitumoral immune response mediated by the induction of IFNs, and ISGs and other cytokines along with reduction of Tregs. SB 11285 is being advanced to human clinical trials. Citation Format: Sreerupa Challa, Balaji Ramachandran, Lalitha Vijayakrishnan, Douglas Weitzel, Shenghua Zhou, Kris Iyer. Pharmacodynamic studies of SB 11285, a systemically bioavailable STING agonist in orthotopic tumor models [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr B96.

Ibrutinib treatment inhibits breast cancer progression and metastasis by inducing conversion of myeloid‐derived suppressor cells to dendritic cells

Ibrutinib is a known irreversible inhibitor of Bruton tyrosine kinase (BTK) and interleukin‐2‐inducible kinase (ITK). Ibrutinib has multiple immunomodulatory effects and is currently approved for treatment of chronic lymphocytic leukemia (CLL) and other cancers. Although previous studies have shown that ibrutinib inhibits growth of breast cancer cells, its impact on treatment of breast cancer and its metastasis is not determined. Myeloid‐derived Suppressor Cells (MDSCs) are immature myeloid cells present in tumors that can subdue the development of important tumoricidal cell populations, and their presence has been linked to poor prognosis in human and murine models. Here, using an orthotopic mouse breast cancer model, we show that ibrutinib effectively inhibits progression and metastasis of breast cancer. Mice treated with Ibrutinib display significantly lower tumor burdens and metastasis compared to controls. Furthermore, spleens and tumors from Ibrutinib‐treated mice showed higher numbers of mature DCs and lower numbers of myeloid‐derived suppressor Cells (MDSCs) which promote disease progression and are linked to poor prognosis in human and murine models. We also confirmed that ex vivo treatment of MDSCs with ibrutinib switched their phenotype to mature DCs and significantly enhanced MHCII expression. Further, ibrutinib treatment promoted T cell proliferation and effector functions leading to induction of anti‐tumor TH1 and CTL immune responses. Taken together, our results indicate that Ibrutinib inhibits tumor development and metastasis in breast cancer by promoting development of mature DCs from MDSCs and hence could be a novel therapeutic agent for treatment of breast cancerSupport or Funding InformationPharmacyclics LLC, an AbbVie Company

Studying Triple Negative Breast Cancer Using Orthotopic Breast Cancer Model.

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with limited therapeutic options. When compared to patients with less aggressive breast tumors, the 5-year survival rate of TNBC patients is 77% due to their characteristic drug-resistant phenotype and metastatic burden. Toward this end, murine models have been established aimed at identifying novel therapeutic strategies limiting TNBC tumor growth and metastatic spread. This work describes a practical guide for the TNBC orthotopic model where MDA-MB-231 breast cancer cells suspended in a basement membrane matrix are implanted in the fourth mammary fat pad, which closely mimics the cancer cell behavior in humans. Measurement of tumors by caliper, lung metastasis assessment via in vivo and ex vivo imaging, and molecular detection are discussed. This model provides an excellent platform to study therapeutic efficacy and is especially suitable for the study of the interaction between the primary tumor and distal metastatic sites.

Studying Triple Negative Breast Cancer Using Orthotopic Breast Cancer Model

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with limited therapeutic options. When compared to patients with less aggressive breast tumors, the 5-year survival rate of TNBC patients is 77% due to their characteristic drug-resistant phenotype and metastatic burden. Toward this end, murine models have been established aimed at identifying novel therapeutic strategies limiting TNBC tumor growth and metastatic spread. This work describes a practical guide for the TNBC orthotopic model where MDA-MB-231 breast cancer cells suspended in a basement membrane matrix are implanted in the fourth mammary fat pad, which closely mimics the cancer cell behavior in humans. Measurement of tumors by caliper, lung metastasis assessment via in vivo and ex vivo imaging, and molecular detection are discussed. This model provides an excellent platform to study therapeutic efficacy and is especially suitable for the study of the interaction between the primary tumor and distal metastatic sites.

Time-dependent interactions of blood platelets and cancer cells, accompanied by extramedullary hematopoiesis, lead to increased platelet activation and reactivity in a mouse orthotopic model of breast cancer - implications for pulmonary and liver metastasis.

Aging has become a significant risk factor for several diseases, including breast cancer.Platelet activation and platelet-cancer cell aggregate fractions were found to increase with tumor progression in a mouse model of breast cancer. At advanced stages of tumor development, platelets from mice with breast cancer were hyperreactive to low agonist concentrations and hyporeactive to high ones. Platelet activation and reactivity were strongly associated with breast cancer metastasis in the lungs and extramedullary hematopoiesis in the liver. A greater fraction of platelet aggregates was observed in 4T1-injected mice at the advanced stages of breast cancer. In vitro, platelet activation was elevated after incubation with 4T1 cells, and thrombin-stimulated platelets formed aggregates with 4T1 cells. Neither GPIbα, nor GPIIb/IIIa blocking antibodies, were able to affect platelet-cancer cell aggregation in vitro.The primed circulating platelets became more sensitive to subthreshold stimuli at advanced stages of tumor development, and the formation of platelet-cancer cell aggregates increased with cancer progression. Our findings demonstrate that the age-associated progression of breast cancer cells is connected with increased platelet functioning, and that it can be manifested by the increased number of metastases and extramedullary hematopoiesis in a time-dependent-manner.

Inhibition of IDO leads to IL-6-dependent systemic inflammation in mice when combined with photodynamic therapy

It was previously reported that the activation of antitumor immune response by photodynamic therapy (PDT) is crucial for its therapeutic outcome. Excessive PDT-mediated inflammation is accompanied by immunosuppressive mechanisms that protect tissues from destruction. Thus, the final effect of PDT strongly depends on the balance between the activation of an adoptive arm of immune response and a range of activated immunosuppressive mechanisms. Here, with flow cytometry and functional tests, we evaluate the immunosuppressive activity of tumor-associated myeloid cells after PDT. We investigate the antitumor potential of PDT combined with indoleamine 2,3-dioxygenase 1 (IDO) inhibitor in the murine 4T1 and E0771 orthotopic breast cancer models. We found that the expression of IDO, elevated after PDT, affects the polarization of T regulatory cells and influences the innate immune response. Our results indicate that, depending on a therapeutic scheme, overcoming IDO-induced immunosuppressive mechanisms after PDT can be beneficial or can lead to a systemic toxic reaction. The inhibition of IDO, shortly after PDT, activates IL-6-dependent toxic reactions that can be diminished by the use of anti-IL-6 antibodies. Our results emphasize that deeper investigation of the physiological role of IDO, an attractive target for immunotherapies of cancer, is of great importance.

Abstract P3-01-11: Targeting RAGE inhibits breast cancer invasion and metastasis

Abstract Background: Breast cancer (BC) is treatable with early detection, but once metastasis occurs, there is no cure. Therefore, it is of upmost importance to find targetable biomarkers that are involved in modulating the multi-step metastatic process. The Receptor for Advanced Glycation Endproducts (RAGE) and its ligands are an inflammatory pathway that are involved in modulating breast cancer progression and metastasis. We recently demonstrated that genetic or pharmacological interruption of RAGE signaling affected tumor progression and metastasis. However, no studies have dissected the role of RAGE in tumor growth from the metastatic cascade. Here, we show for the first time in multiple metastatic breast cancer models that targeting RAGE impairs BC metastasis. Methods: We tested the anti-metastatic effect of RAGE in vitro using the RAGE inhibitor FPS-ZM1 or RAGE shRNA knockdown in cell invasion, proliferation, migration and sphere formation assays (with 4T1, Py8119 and E0771 mouse BC cells). For in vivo assays we used orthotopic BC models (4T1/BALB/c and E0771 & Py8119/C57BL6) and experimental metastasis assays (tail vein injection of 4T1/BALB/c and Py8119/C57BL6). To target RAGE, we used genetic (shRNA in 4T1 cells and RAGE knockout in C57BL6 mice) and pharmacological approaches (I.P. injection of FPS-ZM1). To investigate the synergistic effects of RAGE inhibition on progression and metastasis, we tested combination therapy of low-dose doxorubicin and FPS-ZM1. Results: Inhibition of RAGE with FPS-ZM1 (1-5uM) impaired tumor cell invasion of 4T1, E0771 and Py8119 cells. Similarly, in spheroid assays, treatment of cells with FPS-ZM1 resulted in fewer and smaller colonies. However, FPS-ZM1 treatment did not affect cell proliferation. In vivo studies revealed that FPS-ZM1 (1mg/kg) has a modest effect on tumor growth in 4T1/BALB/c injected mice but displayed a dramatic inhibitory effect on metastasis to the lungs. In experimental metastasis assays, tail-vein injection of 4T1 cells in BALB/c mice demonstrated that FPS-ZM1 treatment strongly impaired metastatic disease in mice compared to controls. To dissect the genetic role of RAGE in the tumor versus host, we test the effect of RAGE knockdown in 4T1 cells in experimental metastasis assays. RAGE shRNA impaired metastasis to the lungs, albeit to a lower degree seen with the RAGE inhibitor. To test the role of the host, we injected Py8119 cells into wild-type and RAGE knockout (RKO) mice. RKO mice displayed fewer metastatic burden compared to wild-type mice. Finally, in our combination treatment experiments, treatment of 4T1-injected BALB/c mice with Doxorubicin and FPS-ZM1 (alone and in combination), demonstrated that drug combination was more effective in inhibiting lung metastasis than either reagent alone. We are currently assessing how RAGE mechanistically drives these metastatic changes. Conclusion: Our data strongly suggests RAGE plays an important role in breast cancer metastasis, with less of an effect on tumor growth. Ongoing studies in our lab are testing which stage of the metastatic cascade RAGE is involved in, and the underlying mechanisms driving these processes. In conclusion, the use of RAGE inhibitors could represent a novel therapeutic approach for metastatic breast cancer. Citation Format: Gyong Ha Hwang, Melinda Magna, Barbara Mera, Toni Yeasky, Taekyoung Kwak, Lucas Outcault, Masaru Takabatake, Thuy-Mai Le, Marc E. Lippman, Barry I. Hudson. Targeting RAGE inhibits breast cancer invasion and metastasis [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-01-11.

Abstract P3-01-03: Modulating inflammation with nucleic acid scavengers to prevent breast cancer metastasis

Abstract Rationale: Chronic inflammation is a hallmark of cancer. Inflammation, whether it is an underlying baseline condition or induced/exacerbated due to treatment, is a major hurdle that ultimately impacts the efficacy of standard of care therapy. However, no strategy exists to effectively control endogenous or therapy-induced inflammation in women with breast cancer. Moreover, there is limited information on how endogenous or therapy-induced inflammation modulates immune cells in women with breast cancer. Nucleic acid-containing pro-inflammatory complexes, termed Nucleic Acid-containing Damage Associated Molecular Patterns (NA-DAMPs), are released from dead or dying cancer cells or activated immune cells. NA-DAMPs activate nucleic acid sensing toll-like receptors (TLR) and other pattern recognition receptors (PRR). NA-DAMPs promote tumor progression and metastasis by inducing pro-tumorigenic signaling in cancer cells. Excessive and persistent NA-DAMP-mediated PRR signaling in immune cells is associated with immune dysfunction. Nucleic acid binding polymers have been used as vehicles for DNA/RNA delivery. We have discovered that a subset of nucleic acid binding polymers, termed nucleic acid scavengers (NAS), act as anti-inflammatory agents by capturing cancer-promoting pro-inflammatory NA-DAMPs. Therefore, we investigated if a NAS could limit cancer progression and metastasis by capturing and mitigating the effects of NA-DAMPs in immunocompetent murine models of breast cancer. Methods: We tested the use of the NAS PAMAM-G3 in the 1] orthotopic surgical resection 4T1 breast cancer model; 2] intravenous experimental metastasis 4T1 breast cancer model; 3] MMTV-PyMT spontaneous breast cancer model. We also measured changes in inflammation/inflammatory cell profile in tumor and in blood. Next, we investigated the relationship between therapy, NA-DAMPs and immune cell profile in blood from women with breast cancer. We also examined if NA-DAMPs in patient serum induces tumor invasion and if the NAS PAMAM-G3 prevents tumor invasion using an in vitro assay. Results: We have determined that the NAS PAMAM-G3 controls lung metastasis in immunocompetent murine models of breast cancer and our data indicate that: 1] chronic inflammation and inflammatory cells in the tumor and periphery promote cancer invasion and metastasis; 2] modulating inflammation by removing excessive NA-DAMPs using the NAS PAMAM-G3 limits cancer metastasis; 3] scavenging inflammation-associated NA-DAMPs significantly alters immune cell and cytokine/chemokine profile in the tumor and periphery, promotes T cell infiltration in the tumor and induces antitumor CD8+ T cell responses. In experiments conducted using blood collected longitudinally from women undergoing standard of care therapy, we observed that: 1] NA-DAMPs and inflammatory monocytes are elevated in women undergoing standard of care therapy; 2] Post-chemotherapy breast cancer patient serum increases invasion/migration of human breast cancer cells in vitro; 3] PAMAM-G3 abrogates increase in invasion/migration of human breast cancer cells in vitro in response to post-chemotherapy breast cancer patient serum. Conclusions: These results highlight the potential utility of NAS to treat cancer associated inflammation and thereby inhibit cancer metastasis by 1) limiting extracellular NA-DAMP-induced persistent activation of pro-inflammatory signaling, and 2) promoting full engagement of both the innate and adaptive immune systems. These principles will aid in the development of a novel anti-metastatic therapy for women with breast cancer. This work is supported by Department of Defense Breast Cancer Research Program Awards W81XWH-16-1-0512 (Nair) and W81XWH-16-1-0513 (Sullenger). Citation Format: Smita Nair, Eda Holl, Karenia Landa, Victoria Frazier, Elias Eteshola, David Boczkowski, Rachel Rempel, Shelley Hwang, Bruce Sullenger. Modulating inflammation with nucleic acid scavengers to prevent breast cancer metastasis [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-01-03.

Ibrutinib treatment inhibits breast cancer progression and metastasis by inducing conversion of myeloid-derived suppressor cells to dendritic cells

BackgroundIbrutinib is a Bruton’s tyrosine kinase (BTK) and interleukin-2-inducible kinase (ITK) inhibitor used for treating chronic lymphocytic leukaemia (CLL) and other cancers. Although ibrutinib is known to inhibit the growth of breast cancer cell growth in vitro, its impact on the treatment and metastasis of breast cancer is unclear.MethodsUsing an orthotopic mouse breast cancer model, we show that ibrutinib inhibits the progression and metastasis of breast cancer.ResultsIbrutinib inhibited proliferation of cancer cells in vitro, and Ibrutinib-treated mice displayed significantly lower tumour burdens and metastasis compared to controls. Furthermore, the spleens and tumours from Ibrutinib-treated mice contained more mature DCs and lower numbers of myeloid-derived suppressor cells (MDSCs), which promote disease progression and are linked to poor prognosis. We also confirmed that ex vivo treatment of MDSCs with ibrutinib switched their phenotype to mature DCs and significantly enhanced MHCII expression. Further, ibrutinib treatment promoted T cell proliferation and effector functions leading to the induction of antitumour TH1 and CTL immune responses.ConclusionsIbrutinib inhibits tumour development and metastasis in breast cancer by promoting the development of mature DCs from MDSCs and hence could be a novel therapeutic agent for the treatment of breast cancer.

Carfilzomib Delivery by Quinic Acid-Conjugated Nanoparticles: Discrepancy Between Tumoral Drug Accumulation and Anticancer Efficacy in a Murine 4T1 Orthotopic Breast Cancer Model

Despite being a major breakthrough in multiple myeloma therapy, carfilzomib (CFZ, a second-generation proteasome inhibitor drug) has been largely ineffective against solid cancer, possibly due to its pharmacokinetic drawbacks including metabolic instability. Recently, quinic acid (QA, a low-affinity ligand of selectins upregulated in peritumoral vasculature) was successfully utilized as a surface modifier for nanoparticles containing paclitaxel. Here, we designed QA-conjugated nanoparticles containing CFZ (CFZ@QANP; the surface of poly(lactic-co-glycolic acid) nanoparticles modified by conjugation with a QA derivative). Compared to the clinically used cyclodextrin-based formulation (CFZ-CD), CFZ@QANP enhanced the metabolic stability and in vivo exposure of CFZ in mice. CFZ@QANP, however, showed little improvement in suppressing tumor growth over CFZ-CD against the murine 4T1 orthotopic breast cancer model. CFZ@QANP yielded no enhancement in proteasomal inhibition in excised tumors despite having a higher level of remaining CFZ than CFZ-CD. These results likely arise from delayed, incomplete CFZ release from CFZ@QANP as observed using biorelevant media in vitro. These results suggest that the applicability of QANP may not be predicted by physicochemical parameters commonly used for formulation design. Our current results highlight the importance of considering drug release kinetics in designing effective CFZ formulations for solid cancer therapy.

Inhibition of Autotaxin with GLPG1690 Increases the Efficacy of Radiotherapy and Chemotherapy in a Mouse Model of Breast Cancer

Autotaxin catalyzes the formation of lysophosphatidic acid, which stimulates tumor growth and metastasis and decreases the effectiveness of cancer therapies. In breast cancer, autotaxin is secreted mainly by breast adipocytes, especially when stimulated by inflammatory cytokines produced by tumors. In this work, we studied the effects of an ATX inhibitor, GLPG1690, which is in phase III clinical trials for idiopathic pulmonary fibrosis, on responses to radiotherapy and chemotherapy in a syngeneic orthotopic mouse model of breast cancer. Tumors were treated with fractionated external beam irradiation, which was optimized to decrease tumor weight by approximately 80%. Mice were also dosed twice daily with GLPG1690 or vehicle beginning at 1 day before the radiation until 4 days after radiation was completed. GLPG1690 combined with irradiation did not decrease tumor growth further compared with radiation alone. However, GLPG1690 decreased the uptake of 3'-deoxy-3'-[18F]-fluorothymidine by tumors and the percentage of Ki67-positive cells. This was also associated with increased cleaved caspase-3 and decreased Bcl-2 levels in these tumors. GLPG1690 decreased irradiation-induced C-C motif chemokine ligand-11 in tumors and levels of IL9, IL12p40, macrophage colony-stimulating factor, and IFNγ in adipose tissue adjacent to the tumor. In other experiments, mice were treated with doxorubicin every 2 days after the tumors developed. GLPG1690 acted synergistically with doxorubicin to decrease tumor growth and the percentage of Ki67-positive cells. GLPG1690 also increased 4-hydroxynonenal-protein adducts in these tumors. These results indicate that inhibiting ATX provides a promising adjuvant to improve the outcomes of radiotherapy and chemotherapy for breast cancer.

Legumain-deficient macrophages promote senescence of tumor cells by sustaining JAK1/STAT1 activation.

Macrophages serve as the first line of communication between tumors and the rest of the immune system, and understanding the interplay between macrophage and tumor cells is essential for developing novel macrophage-based strategy against tumor. Here, we show that deletion of legumain in macrophages activates senescence of tumor cells. Macrophage derived IL-1β mediates the pro-senescent effect of Lgmn-/- macrophages since blockage of IL-1β reverses the senescence phenotype in both a coculture model of macrophage and tumor cells and an orthotopic mouse model of breast cancer. Sustained activation of JAK1/STAT1 signaling and increased iNOS were found in the tumor cell-cocultured Lgmn-/- macrophages, which were necessary for IL-1β expression and secretion. Applying a specific STAT1 agonist mimics the inductive effect of legumain deletion on IL-1β expression in macrophages, and the effect can be blocked via inhibition of iNOS. Legumain and integrin αvβ3 interact to prevent STAT1 signaling in macrophages, and blockage of integrin αvβ3 stimulates STAT1 activation. Therapeutically, transplantation of bone marrow from Lgmn-/- mice suppresses the malignant growth of tumor by upregulating tumor cell senescence. Therefore, our finding highlights legumain in macrophages as a potential therapeutic target for tumors.

A Novel Antitumor Strategy: Simultaneously Inhibiting Angiogenesis and Complement by Targeting VEGFA/PIGF and C3b/C4b

Therapeutic antibodies targeting vascular endothelial growth factor (VEGF) have become a critical regimen for tumor therapy, but the efficacy of monotherapy is usually limited by drug resistance and multiple angiogenic mechanisms. Complement proteins are becoming potential candidates for cancer-targeted therapy based on their role in promoting cancer progression and angiogenesis. However, the antitumor abilities of simultaneous VEGF and complement blockade were unknown. We generated a humanized soluble VEGFR-Fc fusion protein (VID) binding VEGFA/PIGF and a CR1-Fc fusion protein (CID) targeting C3b/C4b. Both VID and CID had good affinities to their ligands and showed effective bioactivities. In vitro, angiogenesis effects induced by VEGF and hemolysis induced by complement were inhibited by VID and CID, respectively. Further, VID and CID confer a synergetic therapeutic effect in a colitis-associated colorectal cancer (CAC) model and an orthotopic 4T1 breast cancer model. Mechanically, combination therapy inhibited tumor angiogenesis, cell proliferation, and MDSC infiltration in the tumor microenvironment and promoted tumor cell apoptosis. Our study offers a novel therapeutic strategy for anti-VEGF-resistant tumors and chronic-inflammation-associated tumors.

A novel metadherinΔ7 splice variant enhances triple negative breast cancer aggressiveness by modulating mitochondrial function via NFĸB-SIRT3 axis.

Metadherin (MTDH) expression inversely correlates with prognosis of several cancers including mammary carcinomas. In this work, we identified a novel splice variant of MTDH with exon7 skipping (MTDHΔ7) and its levels were found significantly high in triple negative breast cancer (TNBC) cells and in patients diagnosed with TNBC. Selective overexpression of MTDHΔ7 in MDA-MB-231 and BT-549 cells enhanced proliferation, invasion, and epithelial-to-mesenchymal (EMT) transition markers in comparison to its wildtype counterpart. In contrast, knockdown of MTDHΔ7 induced antiproliferative/antiinvasive effects. Mechanistically, MTDH-NFĸB-p65 complex activated SIRT3 transcription by binding to its promoter that in turn enhanced MnSOD levels and promoted EMT in TNBC cells. Intriguingly, mitochondrial OCR through Complex-I and -IV, and glycolytic rate (ECAR) were significantly high in MDA-MB-231 cells stably expressing MTDHΔ7. While depletion of SIRT3 inhibited MTDH-Wt/Δ7-induced OCR and ECAR, knockdown of MnSOD inhibited only ECAR. In addition, MTDH-Wt/Δ7-mediated pro-proliferative/-invasive effects were greatly obviated with either siSIRT3 or siMnSOD in these cells. The functional relevance of MTDHΔ7 was further proved under in vivo conditions in an orthotopic mouse model of breast cancer. Mice bearing labeled MDA-MB-231 cells stably expressing MTDHΔ7 showed significantly more tumor growth and metastatic ability to various organs in comparison to MTDH-Wt bearing mice. Taken together, MTDHΔ7 promotes TNBC aggressiveness through enhanced mitochondrial biogenesis/function, which perhaps serves as a biomarker.

Sulforaphane Mediates Glutathione Depletion via Polymeric Nanoparticles to Restore Cisplatin Chemosensitivity.

Platinum (Pt)-based chemotherapy is a broadly used therapeutic regimen against various cancers. However, the insufficient cellular uptake, deactivation by thiol-containing species and nonspecific distribution of cisplatin (CDDP) result in its low chemosensitivity as well as systemic side effects, which can largely constrain the employment of CDDP in clinical treatment. To circumvent these problems, in this study, polymeric nanoparticles were utilized to codeliver a water-soluble CDDP derivative, poly(γ,l-glutamic acid)-CDDP conjugate, and a naturally occurring compound derived from broccoli, sulforaphane, which can achieve efficient glutathione (GSH) depletion, to improve the accumulation of CDDP in cancer cells. Results show that compared with combinational treatment of CDDP and SFN, the nanoparticles were more effectively internalized and could significantly reduce GSH content in breast cancer cells, leading to a notable increase in DNA-bound Pt and DNA damage-induced apoptosis. Moreover, in an orthotopic breast cancer model, the nanoparticles achieved a significantly higher tumor accumulation and exhibited a more powerful antitumor activity. Finally, this nanoenhanced chemotherapy was further confirmed in a liver cancer model with high-expression of GSH. Taken together, this sulforaphane-based nanostrategy holds great promise to enhance the sensitivity and therapeutic efficacy of Pt-based chemotherapy.

Metformin overcomes resistance to cisplatin in triple-negative breast cancer (TNBC) cells by targeting RAD51

BackgroundChemotherapy is a standard therapeutic regimen to treat triple-negative breast cancer (TNBC); however, chemotherapy alone does not result in significant improvement and often leads to drug resistance in patients. In contrast, combination therapy has proven to be an effective strategy for TNBC treatment. Whether metformin enhances the anticancer effects of cisplatin and prevents cisplatin resistance in TNBC cells has not been reported.MethodsCell viability, wounding healing, and invasion assays were performed on Hs 578T and MDA-MB-231 human TNBC cell lines to demonstrate the anticancer effects of combined cisplatin and metformin treatment compared to treatment with cisplatin alone. Western blotting and immunofluorescence were used to determine the expression of RAD51 and gamma-H2AX. In an in vivo 4T1 murine breast cancer model, a synergistic anticancer effect of metformin and cisplatin was observed.ResultsCisplatin combined with metformin decreased cell viability and metastatic effect more than cisplatin alone. Metformin suppressed cisplatin-mediated RAD51 upregulation by decreasing RAD51 protein stability and increasing its ubiquitination. In contrast, cisplatin increased RAD51 expression in an ERK-dependent manner. In addition, metformin also increased cisplatin-induced phosphorylation of γ-H2AX. Overexpression of RAD51 blocked the metformin-induced inhibition of cell migration and invasion, while RAD51 knockdown enhanced cisplatin activity. Moreover, the combination of metformin and cisplatin exhibited a synergistic anticancer effect in an orthotopic murine model of 4T1 breast cancer in vivo.ConclusionsMetformin enhances anticancer effect of cisplatin by downregulating RAD51 expression, which represents a novel therapeutic target in TNBC management.

The Immunomodulatory Effects of Carbon-Ion Therapy on Solid Tumors

Radiation-induced immunostimulation is of great interest as a focal strategy to reinvigorate or augment an immunotherapy-induced tumor-specific response. While evidence supports photon therapy (PhRT) as a tumor immunomodulator, pre-clinical data suggest that carbon-ion therapy (CiRT) may be more potent. Here we evaluate the immunomodulatory effects of CiRT, compared to biologically equivalent doses (BEDs) of PhRT, in a breast cancer mouse model. Using the orthotopic 4T1 mouse breast cancer model, we evaluated the immunomodulatory effects of very low (0.4 Gy), low (1 Gy) and high (4 Gy) doses of CiRT (290 MeV/u, SOBP) delivered to mammary tumors at the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan compared to BEDs (RBE 2) of PhRT (SARRP, Xstrahl; 220 kV). Primary tumors were treated 7-days post implantation and harvested 72-hours later for flow cytometric characterization of tumor-infiltrating lymphocytes. Low (1 Gy) and high-dose (4 Gy) CiRT resulted in a 32% and 51% (p<0.01) decrease in CD4+ T-cells, with no significant change following very low-dose (0.4 Gy) CiRT. Whereas, very low, low, and high-dose PhRT reduced CD4+ T-cells by 50%, 32% and 44% (p<0.05) and very low and high-dose PhRT reduced CD8+ T-cells by 55% and 47% (p<0.05), compared to control. Very high-dose (4 Gy) CiRT induced a 184% and 117% (p<0.05) increase in proliferation (Ki67+) by CD4+ and CD8+ T-cells, respectively, compared to control. While, very low, low and high-dose PhRT increased proliferation of CD4+ T-cells by 170%, 129% and 216% (p<0.05) and CD8+ T-cells by 84%, 86% and 99% (p<0.05), compared to control. High-dose (4 Gy) CiRT induced pro-inflammatory cytokines production including granzyme B (88%, 205% increase; P<0.005), IL-2 (112%, 165% increase, p<0.01) and TNF-a (230%, 117%, p<0.005) by CD4+ and CD8+ T-cells, respectively, with no change in IFN-g expression. Whereas, high-dose PhRT increased IFN-g expression by 102% (p<0.05) by CD8+ T-cells, with no change in granzyme B, IL-2, or TNF-a. Only high-dose (4 Gy) CiRT induced a 127% increase (p<0.005) in abundance and a 70% (p<0.05) increase proliferation of immunosuppressive regulatory T-cells (Tregs), whereas very low and high-dose PhRT increased proliferation of Tregs by 82% and 99% (p<0.05), respectively, with no increase in abundance. These data suggest that at low doses, lymphocytes differ in their sensitivity to CiRT compared to PhRT, whereby very low dose CiRT is lymphocyte-sparing. Very high-dose CiRT and PhRT induced immunostimulatory effects by differing degrees and through different mechanisms, CiRT being more potent and inducing changes in a diverse set of pro-inflammatory cytokines including granzyme B, IL-2 and TNF-a, whereas PhRT induced only IFN-g. Combining less lymphotoxicity at low doses with a more potent and mechanistically diverse pro-inflammatory effects at high doses, CiRT may be a more optimal synergistic tool to augment an immunotherapy-induced, tumor-specific response.

Ultrathin Metal-Organic-Layer Mediated Radiotherapy-Radiodynamic Therapy

Summary Checkpoint blockade immunotherapy (CBI) is effective in promoting a systemic immune response against some metastatic tumors. The reliance on the pre-existing immune environment of the tumor, however, limits the efficacy of CBI on a broad spectrum of cancers. Herein, we report the design of a novel nanoscale metal-organic layer (nMOL), Hf-MOL, for effective treatment of local tumors by enabling radiotherapy-radiodynamic therapy (RT-RDT) with low-dose X-rays and, when in combination with an immune checkpoint inhibitor, regression of metastatic tumors by reactivating antitumor immunity and inhibiting myeloid-derived suppressor cells. Owing to the reduced dimensionality, nMOLs allow facile diffusion of reactive oxygen species and exhibit superior RT-RDT effects. The synergy of Hf-MOL-enabled RT-RDT immune activation and anti-programmed death ligand 1 CBI led to robust abscopal effects on a series of bilateral models of colon, head and neck, and breast cancers, as well as significant antimetastatic effects on an orthotopic model of breast cancer.

Investigating circulating tumor cells and distant metastases in patient-derived orthotopic xenograft models of triple-negative breast cancer

BackgroundCirculating tumor cells (CTCs) represent a temporal “snapshot” of a patient’s cancer and changes that occur during disease evolution. There is an extensive literature studying CTCs in breast cancer patients, and particularly in those with metastatic disease. In parallel, there is an increasing use of patient-derived models in preclinical investigations of human cancers. Yet studies are still limited demonstrating CTC shedding and metastasis formation in patient-derived models of breast cancer.MethodsWe used seven patient-derived orthotopic xenograft (PDOX) models generated from triple-negative breast cancer (TNBC) patients to study CTCs and distant metastases. Tumor fragments from PDOX tissue from each of the seven models were implanted into 57 NOD scid gamma (NSG) mice, and tumor growth and volume were monitored. Human CTC capture from mouse blood was first optimized on the marker-agnostic Vortex CTC isolation platform, and whole blood was processed from 37 PDOX tumor-bearing mice.ResultsStaining and imaging revealed the presence of CTCs in 32/37 (86%). The total number of CTCs varied between different PDOX tumor models and between individual mice bearing the same PDOX tumors. CTCs were heterogeneous and showed cytokeratin (CK) positive, vimentin (VIM) positive, and mixed CK/VIM phenotypes. Metastases were detected in the lung (20/57, 35%), liver (7/57, 12%), and brain (1/57, less than 2%). The seven different PDOX tumor models displayed varying degrees of metastatic potential, including one TNBC PDOX tumor model that failed to generate any detectable metastases (0/8 mice) despite having CTCs present in the blood of 5/5 tested, suggesting that CTCs from this particular PDOX tumor model may typify metastatic inefficiency.ConclusionPDOX tumor models that shed CTCs and develop distant metastases represent an important tool for investigating TNBC.