Anti-metastatic effects of AGS-30 on breast cancer through the inhibition of M2-like macrophage polarization

AGS-30, a new andrographolide derivative, showed significant anticancer and anti-angiogenic characteristics. However, its role in controlling macrophage polarization and tumor immune response is unknown. Thus, the main goals of this study are to investigate how AGS-30 regulates macrophage polarization and how it suppresses breast cancer metastasis. AGS-30 inhibited IL-4 and IL-13-induced RAW 264.7 and THP-1 macrophages into M2-like phenotype. However, AGS-30 did not affect the LPS and IFN-γ-induced polarization of M1-like macrophages. AGS-30 reduced the mRNA expressions of CD206, Arg-1, Fizz-1, Ym-1, VEGF, IL-10, MMP2, and MMP9 in M2-like macrophages in a concentration-dependent manner. In contrast, andrographolide treatment at 5 μM did not affect M1-like and M2-like macrophage polarization. The conditioned medium from M2-like macrophages increased 4T1 breast cancer cell migration and invasion, whereas AGS-30 inhibited these effects. In the 4T1 breast tumor xenograft mice, the tumor volume and weight were reduced without affecting body weight after receiving AGS-30. AGS-30 treatment also reduced lung and liver metastasis, with reduced STAT6, CD31, VEGF, and Ki67 protein expressions. Moreover, the tumors had considerably fewer M2-like macrophages and Arg-1 expression, but the proportion of M1-like macrophages and iNOS expression increased after AGS-30 treatment. Same results were found in the tail vein metastasis model. In conclusion, this study shows that AGS-30 inhibits breast cancer growth and metastasis, probably through inhibiting M2-like macrophage polarization. Our findings suggest that AGS-30 may be a potential immunotherapeutic alternative for metastatic breast cancer.

Effectiveness of Rhenium(I)-diselenoether Low Doses in a Triple-negative Breast Cancer Chicken Embryo Model

BACKGROUND/AIM

Rhenium(I)-diselenoether (Re-diSe) is a promising anticancer agent composed of one rhenium and two selenium atoms. Its effectiveness was established in inhibiting cancer cells while maintaining low toxicity toward normal cells at a 5 μM dose for 120 hours in MDA-MB-231 cells. In MDA-MB-231 breast tumor-bearing mice, anti-tumor and anti-metastatic effects were observed at a 10 mg/kg dose. However, contradictory results were observed in the 4T1 breast cancer model, where a dose of 60 mg/kg had a pro-tumor effect. To address these discrepancies, the efficacy of Re-diSe at the effective 10 mg/kg dose was validated in a transplanted MDA-MB-231 breast tumor model using the chicken chorioallantoic membrane assay.

MATERIALS AND METHODS

MDA-MB-231 cancer cells were xenografted onto the chicken chorioallantoic membrane (CAM), and daily drug administration was carried out for nine days at doses of 0.1, 1, and 10 mg/kg. At the study's conclusion, a standard histological analysis was conducted.

RESULTS

The low dose of 0.1 mg/kg showed a significant reduction in tumor weights compared to controls. The 1 mg/kg dose resulted in an increased inflammation score but did not induce a significant difference in tumor weights compared to the 0.1 mg/kg dose. Notably, at the 10 mg/kg dose, six out of 11 treated embryos displayed no visible signs of tumors. These tumors exhibited extensive tumor necrosis and significant infiltration by inflammatory cells.

CONCLUSION

In this particular model, the anticancer efficacy of Re-diSe was achieved at the low dose of 0.1 mg/kg. The higher dose of 10 mg/kg, while eliminating visible tumors, might have immune-mediated effects, as indicated by substantial tumor necrosis and infiltration by inflammatory cells. Overall, this study successfully demonstrated the effectiveness of Re-diSe as an anticancer agent.

Maduramicin-guided nanotherapy: A polymeric micelles for targeted drug delivery in canine mammary tumors

Canine mammary tumors (CMT) can severely compromise the life quality of the affected dogs through local recurrence, distant metastases and ultimately succumb to death. Recently, more attention has been given to the potential antimetastatic effect of maduramicin (MAD) on breast cancer. However, its poor aqueous solubility and toxicity to normal tissues limit its clinical application. Therefore, to address the drawbacks of MAD and enhance its anticancer and antimetastatic effects, MAD-loaded TPGS polymeric micelles (MAD-TPGS) were prepared by a thin-film hydration technique. The optimized MAD-TPGS exhibited excellent size distribution, stability and improved water solubility. Cellular uptake assays showed that TPGS polymer micelles could enhance drug internalization. Moreover, TPGS synergistically improved the cytotoxicity of MAD by targeting mitochondrial organelles, improving reactive oxygen species levels and reducing the mitochondrial transmembrane potential. More importantly, MAD-TPGS significantly impeded the metastasis of tumor cells. In vivo results further confirmed that, in addition to exhibiting excellent biocompatibility, MAD-TPGS exhibited greater antitumor efficacy than free MAD. Interestingly, MAD-TPGS displayed superior suppression of CMT metastasis via tail vein injection compared to oral administration, indicating its suitability for intravenous delivery. Overall, MAD-TPGS could be applied as a potential antimetastatic cancer agent for CMT.

Strategies for studying immune and non-immune human and canine mammary gland cancer tumour infiltrate

The tumour microenvironment (TME) is usually defined as a cell environment associated with tumours or cancerous stem cells where conditions are established affecting tumour development and progression through malignant cell interaction with non-malignant cells. The TME is made up of endothelial, immune and non-immune cells, extracellular matrix (ECM) components and signalling molecules acting specifically on tumour and non-tumour cells. Breast cancer (BC) is the commonest malignant neoplasm worldwide and the main cause of mortality in women globally; advances regarding BC study and understanding it are relevant for acquiring novel, personalised therapeutic tools. Studying canine mammary gland tumours (CMGT) is one of the most relevant options for understanding BC using animal models as they share common epidemiological, clinical, pathological, biological, environmental, genetic and molecular characteristics with human BC. In-depth, detailed investigation regarding knowledge of human BC-related TME and in its canine model is considered extremely relevant for understanding changes in TME composition during tumour development. This review addresses important aspects concerned with different methods used for studying BC- and CMGT-related TME that are important for developing new and more effective therapeutic strategies for attacking a tumour during specific evolutionary stages.

Matrine Targets BTF3 to Inhibit the Growth of Canine Mammary Tumor Cells

The canine mammary tumor model is more suitable for studying human breast cancer, and the safety concentrations of matrine and the biotin-labeled matrine probe were determined in canine primary mammary epithelial cells, and then selected canine mammary tumor cell lines CHMm and CHMp were incubated with matrine, and cell viability was detected by CCK-8. The biotin-labeled matrine probe was used to pull-down the targets of matrine in canine mammary tumor cells, and the targets were screened in combination with activity-based protein profiling (ABPP) and Genecards database, and verified by qPCR and western blot. The results showed that the maximum non-cytotoxic concentrations of matrine and biotin-labeled matrine probe in canine primary mammary epithelial cells were 250 μg/mL and 500 μg/mL, respectively. Matrine and biotin-labeled matrine probe had a proliferation inhibitory effect time-dependently on CHMm and CHMp cells within a safe concentration range, and induced autophagy in cells. Then BTF3 targets were obtained by applying ABPP and Genecards screening. Cellular thermal shift assay (CETSA) findings indicated that matrine could increase the heat stability of BTF3 protein. Pull-down employing biotin-labeled matrine probe with CHMm and CHMp cell lysates revealed that BTF3 protein was detected in the biotin-labeled matrine probe group and that BTF3 protein was significantly decreased by the addition of matrine. The qPCR and western blot findings of CHMm and CHMp cells treated with matrine revealed that matrine decreased the expression of the BTF3 gene and protein with the extension of the action time, and the impact was more substantial at the protein level, respectively.

Generation and Characterization of SORT1-Targeted Antibody-Drug Conjugate for the Treatment of SORT1-Positive Breast Tumor

Antibody-drug conjugates (ADCs) have greatly improved the outcomes of advanced breast tumors. However, the treatment of breast tumors with existing ADCs is still hindered by many issues, such as tumor antigen heterogeneity and drug resistance. Therefore, ADCs against new targets would provide options for the treatment of these challenges. Sortilin-1 (SORT1) may be a promising target for ADC as it is upregulated in breast cancer. To evaluate the possibility of SORT1 as an ADC target, a humanized antibody_8D302 with high affinity against SORT1 was generated. Additionally, 8D302 was conjugated with MMAE and DXd to generate two ADCs_8D302-MMAE and 8D302-DXd, respectively. Both 8D302-MMAE and 8D302-DXd showed effective cytotoxicity against SORT1 positive breast tumor cell lines and induced bystander killing. Consequently, 8D302-MMAE showed relatively better anti-tumor activity than 8D302-DXd both in vitro and in vivo, but 8D302-DXd had superior safety profile and pharmacokinetics profile over 8D302-MMAE. Furthermore, SORT1 induced faster internalization and lysosomal trafficking of antibodies and had a higher turnover compared with HER2. Also, 8D302-DXd exhibited superior cell cytotoxicity and tumor suppression over trastuzumab-DXd, a HER2-targeted ADC. We hypothesize that the high turnover of SORT1 enables SORT1-targeted ADC to be a powerful agent for the treatment of SORT1-positive breast tumor.

Therapeutic trial of fluvastatin in a cell line xenograft model of canine mammary gland cancer

The Hippo signalling pathway is involved in breast cancer and canine mammary tumour (CMT). This study sought to evaluate the efficacy of fluvastatin on the Hippo pathway and its main effectors, YAP and TAZ, in vivo in a murine CMT cell line xenograft model. On treatment day 1, mice were divided into four groups: vehicle, fluvastatin, doxorubicin or a combination therapy. Tumour volumes were monitored with callipers and tissues harvested on day 28th of treatment. Histopathological examination of tumour tissues and major organs was performed as well as tumour evaluation of necrosis, apoptosis, cellular proliferation, expression of YAP, TAZ and the mRNA levels of four of their target genes (CTGF, CYR61, ANKRD1 and RHAMM2). Results showed a statistically significant variation in tumour volumes only for the combination therapy and final tumour weight only for the doxorubicin group compared to control. There was no significant difference in tumour necrosis, expression of CC3, ki-67, YAP and TAZ measured by immunohistochemistry and in the mRNA levels of the target genes. Unexpectedly, lung metastases were found in the control group (9) and not in the fluvastatin treated group (7). In addition, mass spectrometry-based quantification of fluvastatin reveals concentrations comparable to levels reported to exert therapeutic effects. This study shows that fluvastatin tumours concentration reached therapeutic levels without having an effect on the hippo pathway or various tumour parameters. Interestingly, only the control group had lung metastases. This study is the first to explore the repurposing of statins for cancer treatment in veterinary medicine.

Social Isolation Activates Dormant Mammary Tumors, and Modifies Inflammatory and Mitochondrial Metabolic Pathways in the Rat Mammary Gland

Although multifactorial in origin, one of the most impactful consequences of social isolation is an increase in breast cancer mortality. How this happens is unknown, but many studies have shown that social isolation increases circulating inflammatory cytokines and impairs mitochondrial metabolism. Using a preclinical Sprague Dawley rat model of estrogen receptor-positive breast cancer, we investigated whether social isolation impairs the response to tamoxifen therapy and increases the risk of tumors emerging from dormancy, and thus their recurrence. We also studied which signaling pathways in the mammary glands may be affected by social isolation in tamoxifen treated rats, and whether an anti-inflammatory herbal mixture blocks the effects of social isolation. Social isolation increased the risk of dormant mammary tumor recurrence after tamoxifen therapy. The elevated recurrence risk was associated with changes in multiple signaling pathways including an upregulation of IL6/JAK/STAT3 signaling in the mammary glands and tumors and suppression of the mitochondrial oxidative phosphorylation (OXPHOS) pathway. In addition, social isolation increased the expression of receptor for advanced glycation end-products (RAGE), consistent with impaired insulin sensitivity and weight gain linked to social isolation. In socially isolated animals, the herbal product inhibited IL6/JAK/STAT3 signaling, upregulated OXPHOS signaling, suppressed the expression of RAGE ligands S100a8 and S100a9, and prevented the increase in recurrence of dormant mammary tumors. Increased breast cancer mortality among socially isolated survivors may be most effectively prevented by focusing on the period following the completion of hormone therapy using interventions that simultaneously target several different pathways including inflammatory and mitochondrial metabolism pathways.

Role of a Mixture of Polyphenol Compounds Released after Blueberry Fermentation in Chemoprevention of Mammary Carcinoma: In Vivo Involvement of miR-145

Epigenetic mechanisms such as microRNA (miRNA) deregulation seem to exert a central role in breast cancer initiation and progression. Therefore, targeting epigenetics deregulation may be an effective strategy for preventing and halting carcinogenesis. Studies have revealed the significant role of naturally occurring polyphenolic compounds derived from fermented blueberry fruits in cancer chemoprevention by modulation of cancer stem cell development through the epigenetic mechanism and regulation of cellular signaling pathways. In this study, we first investigated the phytochemical changes during the blueberry fermentation process. Fermentation favored the release of oligomers and bioactive compounds such as protocatechuic acid (PCA), gallic acid, and catechol. Next, we investigated the chemopreventive potentials of a polyphenolic mixture containing PCA, gallic acid, and catechin found in fermented blueberry juice in a breast cancer model by measuring miRNA expression and the signaling pathways involved in breast cancer stemness and invasion. To this end, 4T1 and MDA-MB-231 cell lines were treated with different doses of the polyphenolic mixture for 24 h. Additionally, female Balb/c mice were fed with this mixture for five weeks; two weeks before and three weeks after receiving 4T1 cells. Mammosphere formation was assayed in both cell lines and the single-cell suspension obtained from the tumor. Lung metastases were counted by isolating 6-thioguanine-resistant cells present in the lungs. In addition, we conducted RT-qPCR and Western blot analysis to validate the expression of targeted miRNAs and proteins, respectively. We found a significant reduction in mammosphere formation in both cell lines treated with the mixture and in tumoral primary cells isolated from mice treated with the polyphenolic compound. The number of colony-forming units of 4T1 cells in the lungs was significantly lower in the treatment group compared to the control group. miR-145 expression significantly increased in the tumor samples of mice treated with the polyphenolic mixture compared to the control group. Furthermore, a significant increase in FOXO1 levels was noted in both cell lines treated with the mixture. Overall, our results show that phenolic compounds found in fermented blueberry delay the formation of tumor-initiating cells in vitro and in vivo and reduce the spread of metastatic cells. The protective mechanisms seem to be related, at least partly, to the epigenetic modulation of mir-145 and its signaling pathways.

Antitumor effect of selenium-rich Brazil nuts and selenomethionine dietary supplementation on pre-existing 4T1 mammary tumor growth in mice

Selenium (Se) is an essential micronutrient known to play an important role in the antioxidant system that can potentially influence tumor growth. We aimed to investigate the effects of dietary Se supplementation after detection of 4T1 mammary tumor growth in BALB/c mice. Thirty female mice received subcutaneous inoculation of 4T1 cells. After five days, all animals presenting palpable tumors were randomly assigned to three groups: a control group (Se-control) receiving a diet with adequate Se (0.15 mg/kg) and two other groups that received Se-supplemented diets (1.4 mg/kg of total Se) with either Brazilian nuts (Se-Nuts) or selenomethionine (SeMet). Data were assessed by either One or Two-way ANOVA followed by Tukey's HSD or Bonferroni's post hoc tests, respectively. Both Se-supplemented diets reduced tumor volume from the thirteenth day of feeding compared with the Se-adequate (control) diet (p < 0.05). The SeMet group presented a higher Se blood concentration (p < 0.05) than the Se-control group, with the Se-Nuts group presenting intermediate values. Selenoprotein P gene expression in the liver was higher in the Se-Nuts group than in the Se-control group (p < 0.05), while the SeMet group presented intermediate expression. Dietary Se supplementation, starting after detection of 4T1 palpable lesions, reduced tumor volume in mice.

Reduced infiltration of regulatory T cells in tumours from mice fed daily with gamma-tocotrienol supplementation

Gamma-tocotrienol (γT3) is an analogue of vitamin E with beneficial effects on the immune system, including immune-modulatory properties. This study reports the immune-modulatory effects of daily supplementation of γT3 on host T helper (Th) and T regulatory cell (Treg ) populations in a syngeneic mouse model of breast cancer. Female BALB/c mice were fed with either γT3 or vehicle (soy oil) for 2 weeks via oral gavage before they were inoculated with syngeneic 4T1 mouse mammary cancer cells (4T1 cells). Supplementation continued until the mice were euthanized. Mice (n = 6) were euthanized at specified time-points for various analysis (blood leucocyte, cytokine production and immunohistochemistry). Tumour volume was measured once every 7 days. Gene expression studies were carried out on tumour-specific T lymphocytes isolated from splenic cultures. Supplementation with γT3 increased CD4+ (p < 0.05), CD8+ (p < 0.05) T-cells and natural killer cells (p < 0.05) but suppressed Treg cells (p < 0.05) in peripheral blood when compared to animals fed with the vehicle. Higher interferon (IFN)-γ and lower transforming growth factor (TGF)-ꞵ levels were noted in the γT3 fed mice. Immunohistochemistry findings revealed higher infiltration of CD4+ cells, increased expression of interleukin-12 receptor-beta-2 (IL-12ꞵ2R), interleukin (IL)-24 and reduced expression of cells that express the forkhead box P3 (FoxP3) in tumours from the γT3-fed animals. Gene expression studies showed the down-regulation of seven prominent genes in splenic CD4+ T cells isolated from γT3-fed mice. Supplementation with γT3 from palm oil-induced T cell-dependent cell-mediated immune responses and suppressed T cells in the tumour microenvironment in a syngeneic mouse model of breast cancer.

Submicron particle docetaxel intratumoral injection in combination with anti-mCTLA-4 into 4T1-Luc orthotopic implants reduces primary tumor and metastatic pulmonary lesions

We describe here characterization of the response of local and metastatic disease and immunomodulation following intratumoral (IT) injection of submicron particle docetaxel (SPD) administered alone or in combination with systemic antibody anti-mCTLA-4 (anti-mCTLA-4) in the metastatic 4T1-Luc2-1A4 (4T1) murine breast cancer model. In-life assessments of treatment tolerance, tumor volume (TV), and metastasis were performed (n = 10 animals/group). At study end, immune cell populations in tumor-site tissues and peripheral blood were analyzed using flow cytometry. Signs of distress typical of this aggressive tumor model occurred across all animals except for the combination treated which were asymptomatic and gained weight. TV at study end was significantly reduced in the combination group versus untreated [43% reduced (p < 0.05)] and vehicle controls [54% reduced (p < 0.0001)]. No evidence of thoracic metastasis was found in 40% of combination group animals and thoracic bioluminescence imaging (BLI) was reduced vs. untreated controls (p < 0.01). Significant elevations (p < 0.05) in CD4 + T, CD4 + helper T, Treg, and NKT cells were found in tumor and blood in SPD or combination treatment compared to controls or anti-mCTLA-4. Combination treatment increased tumor-associated CD8 + T cells (p < 0.01), peripheral B cells (p < 0.01), and tumor associated and circulating dendritic cells (DC) (p < 0.05). Tumor-associated NK cells were significantly increased in SPD ± anti-mCTLA-4 treatments (p < 0.01). Myeloid-derived suppressor cells (MDSC) were reduced in bloods in SPD ± anti-mCTLA-4 groups (p < 0.05). These data demonstrate that both SPD and anti-mCTLA-4 produce local anti-tumor effects as well as reductions in metastasis which are significantly enhanced when administered in combination.

Influence of Paclitaxel and Doxorubicin Therapy of ßIII-Tubulin, Carbonic Anhydrase IX, and Survivin in Chemically Induced Breast Cancer in Female Rat

Breast cancer is the most common cancer in females. The aim of this study was to determine the effect of paclitaxel (PTX) and doxorubicin (DOX) therapy on the βIII-tubulin, carbonic anhydrase IX (CA IX), and survivin expression in chemically-induced rat mammary tumors. Animals with induced mammary carcinogenesis were randomly divided into treatment groups and an untreated group. The total proportion of tumors, the proportion of carcinoma in situ (CIS), and invasive carcinoma (IC) were evaluated. Protein expression in tumor tissue was determined using IHC. Statistical analysis of the data, evaluated by Fisher-exact test and unpaired t-test. Significantly increased levels of proteins in the tumor cells were confirmed using the IHC method for all studied proteins. The expression of βIII-tubulin, CA IX, and survivin increased significantly after treatment with both cytostatics (PTX and DOX). Depending on the type of tumor, a significant increase in all proteins was observed in IC samples after PTX treatment, and CA IX expression after DOX treatment. In CIS samples, a significant increase of βIII-tubulin and survivin expression was observed after a DOX treatment. The results suggest that βIII-tubulin, survivin, and CA IX may be significant drug resistance markers and the clinical regulation of their activity may be an effective means of reversing this resistance.

Cholesteryl Ester Promotes Mammary Tumor Growth in MMTV-PyMT Mice and Activates Akt-mTOR Pathway in Tumor Cells

The association between intratumoral cholesteryl ester (CE) and tumor progression has been reported previously. The objective of our study was to investigate a causal effect of CE on mammary tumor progression. Using MMTV-PyMT (MMTV-polyoma virus middle T) transgenic mice and breast tumor cell MCF-7, we show that both exogenous and endogenous CE can increase mammary tumor growth, that CE upregulates the AKT/mTOR pathway, and that CE synthesis blockade suppresses this signaling pathway. Our data suggest that SOAT1, a sterol O-acyltransferase, may be a potential target for the treatment of breast cancer.

Proteomics Approach of Rapamycin Anti-Tumoral Effect on Primary and Metastatic Canine Mammary Tumor Cells In Vitro

Rapamycin is an antifungal drug with antitumor activity and acts inhibiting the mTOR complex. Due to drug antitumor potential, the aim of this study was to evaluate its effect on a preclinical model of primary mammary gland tumors and their metastases from female dogs. Four cell lines from our cell bank, two from primary canine mammary tumors (UNESP-CM1, UNESP-CM60) and two metastases (UNESP-MM1, and UNESP-MM4) were cultured in vitro and investigated for rapamycin IC₅₀. Then, cell lines were treated with rapamycin IC₅₀ dose and mRNA and protein were extracted in treated and non-treated cells to perform AKT, mTOR, PTEN and 4EBP1 gene expression and global proteomics by mass spectrometry. MTT assay demonstrated rapamycin IC₅₀ dose for all different tumor cells between 2 and 10 μM. RT-qPCR from cultured cells, control versus treated group and primary tumor cells versus metastatic tumor cells, did not shown statistical differences. In proteomics were found 273 proteins in all groups, and after data normalization 49 and 92 proteins were used for statistical analysis for comparisons between control versus rapamycin treatment groups, and metastasis versus primary tumor versus metastasis rapamycin versus primary tumor rapamycin, respectively. Considering the two statistical analysis, four proteins, phosphoglycerate mutase, malate dehydrogenase, l-lactate dehydrogenase and nucleolin were found in decreased abundance in the rapamycin group and they are related with cellular metabolic processes and enhanced tumor malignant behavior. Two proteins, dihydrolipoamide dehydrogenase and superoxide dismutase, also related with metabolic processes, were found in higher abundance in rapamycin group and are associated with apoptosis. The results suggested that rapamycin was able to inhibit cell growth of mammary gland tumor and metastatic tumors cells in vitro, however, concentrations needed to reach the IC₅₀ were higher when compared to other studies.

Genistein Reduces the Risk of Local Mammary Cancer Recurrence and Ameliorates Alterations in the Gut Microbiota in the Offspring of Obese Dams

The risk of recurrence of estrogen receptor-positive breast cancer remains constant, even 20 years after diagnosis. Recurrence may be more likely in patients pre-programmed for it already in the womb, such as in the daughters born to obese mothers. Maternal obesity persistently alters offspring’s gut microbiota and impairs tumor immune responses. To investigate if the gut dysbiosis is linked to increased risk of mammary cancer recurrence in the offspring of obese rat dams, we fed adult offspring genistein which is known to have beneficial effects on the gut bacteria. However, the effects of genistein on breast cancer remain controversial. We found that genistein intake after tamoxifen response prevented the increased risk of local recurrence in the offspring of obese dams but had no effect on the control offspring. A significant increase in the abundance of inflammatory Prevotellaceae and Enterobacteriaceae, and a reduction in short-chain fatty acid producing Clostridiaceae was observed in the offspring of obese dams. Genistein supplementation reversed these changes as well as reversed increased gut metabolite N-acetylvaline levels which are linked to increased all-cause mortality. Genistein supplementation also reduced genotoxic tyramine levels, increased metabolites improving pro-resolving phase of inflammation, and reversed the elevated tumor mRNA expression of multiple immunosuppressive genes in the offspring of obese dams. If translatable to breast cancer patients, attempts to prevent breast cancer recurrences might need to focus on dietary modifications which beneficially modify the gut microbiota.

Evaluation of metronomic chemotherapy response using diffusion and dynamic contrast-enhanced MRI

PURPOSE

To investigate the feasibility of using diffusion MRI (dMRI) and dynamic contrast-enhanced (DCE) MRI to evaluate the treatment response of metronomic chemotherapy (MCT) in the 4T1 mammary tumor model of locally advanced breast cancer.

METHODS

Twelve Balb/c mice with metastatic breast cancer were divided into treated and untreated (control) groups. The treated group (n = 6) received five treatments of anti-metabolite agent 5-Fluorouracil (5FU) in the span of two weeks. dMRI and DCE-MRI were acquired for both treated and control groups before and after MCT. Immunohistochemically staining and measurements were performed after the post-MRI measurements for comparison.

RESULTS

The control mice had significantly (p<0.005) larger tumors than the MCT treated mice. The DCE-MRI analysis showed a decrease in contrast enhancement for the control group, whereas the MCT mice had a more stable enhancement between the pre-chemo and post-chemo time points. This confirms the antiangiogenic effects of 5FU treatment. Comparing amplitude of enhancement revealed a significantly (p<0.05) higher enhancement in the MCT tumors than in the controls. Moreover, the MCT uptake rate was significantly (p<0.001) slower than the controls. dMRI analysis showed the MCT ADC values were significantly larger than the control group at the post-scan time point.

CONCLUSION

dMRI and DCE-MRI can be used as potential biomarkers for assessing the treatment response of MCT. The MRI and pathology observations suggested that in addition to the cytotoxic effect of cell kills, the MCT with a cytotoxic drug, 5FU, induced changes in the tumor vasculature similar to the anti-angiogenic effect.

Leptin Modulates the Metastasis of Canine Inflammatory Mammary Adenocarcinoma Cells Through Downregulation of Lysosomal Protective Protein Cathepsin A (CTSA)

Canine malignant mammary gland tumors present with a poor prognosis due to metastasis to other organs, such as lung and lymph node metastases. Unlike in human studies where obesity has been shown to increase the risk of breast cancer, this has not been well studied in veterinary science. In our preliminary study, we discovered that leptin downregulated cathepsin A, which is responsible for lysosomal-associated membrane protein 2a (LAMP2a) degradation. LAMP2a is a rate-limiting factor in chaperone-mediated autophagy and is highly active in malignant cancers. Therefore, in this study, alterations in metastatic capacity through cathepsin A by leptin, which are secreted at high levels in the blood of obese patients, were investigated. We used a canine inflammatory mammary gland adenocarcinoma (CHMp) cell line cultured with RPMI-1640 and 10% fetal bovine serum. The samples were then subjected to real-time polymerase chain reaction, Western blot, immunocytochemistry, and lysosome isolation to investigate and visualize the metastasis and chaperone-mediated autophagy-related proteins. Results showed that leptin downregulated cathepsin A expression at both transcript and protein levels, whereas LAMP2a, the rate-limiting factor of chaperone-mediated autophagy, was upregulated by inhibition of LAMP2a degradation. Furthermore, leptin promoted LAMP2a multimerization through the lysosomal mTORC2 (mTOR complex 2)/PH domain and leucine rich repeat protein phosphatase 1 (PHLPP1)/AKT1 (Serine/threonine-protein kinase 1) pathway. These findings suggest that targeting leptin receptors can alleviate mammary gland cancer cell metastasis in dogs.

Unmodified Rose Bengal photosensitizer conjugated with NaYF4:Yb,Er upconverting nanoparticles for efficient photodynamic therapy

In photodynamic therapy (PDT), photosensitizer (PS) molecules are irradiated by light to generate reactive oxygen species (ROS), the presence of which subsequently leads to cell death. At present, the modality is limited to the treatment of skin diseases because of the low tissue penetration of visible or ultraviolet light required for producing ROS. To increase tissue penetration and extend the therapeutic possibilities of PDT to the treatment of deep-seated cancer, rare-earth doped nanoparticles capable of up-converting infrared to visible light are investigated. These up-converting nanoparticles (UCNPs) are conjugated with PS molecules to efficiently generate ROS. In this work, we employ hexagonal β-NaYF₄:Yb^3 +,Er^3 + as UCNPs and Rose Bengal (RB) as PS molecules and demonstrate efficient in vitro PDT using this nanoformulation. Covalent bonding of the RB molecules is accomplished without their functionalization-an approach which is expected to increase the efficiency of ROS generation by 30%. Spectroscopic studies reveal that our approach results in UCNP surface fully covered with RB molecules. The energy transfer from UCNPs to RB is predominantly non-radiative as evidenced by luminescence lifetime measurements. As a result, ROS are generated as efficiently as under visible light illumination. The in vitro PDT is tested on murine breast 4T1 cancer cells incubated with 250 µg ml^-1 of the nanoparticles and irradiated with NIR light under power density of 2 W cm^-2 for 10 minutes. After 24 hours, the cell viability decreased to 33% demonstrating a very good treatment efficiency. These results are expected to simplify the protocols for preparation of the PDT agents and lead to improved therapeutic effects.

The Assessment of the Combined Treatment of 5-ALA Mediated Photodynamic Therapy and Thalidomide on 4T1 Breast Carcinoma and 2H11 Endothelial Cell Line

Photodynamic therapy (PDT) is a low-invasive method of treatment of various diseases, mainly neoplastic conditions. PDT has been experimentally combined with multiple treatment methods. In this study, we tested a combination of 5-aminolevulinic acid (5-ALA) mediated PDT with thalidomide (TMD), which is a drug presently used in the treatment of plasma cell myeloma. TMD and PDT share similar modes of action in neoplastic conditions. Using 4T1 murine breast carcinoma and 2H11 murine endothelial cells lines as an experimental tumor model, we tested 5-ALA-PDT and TMD combination in terms of cytotoxicity, apoptosis, Vascular Endothelial Growth Factor (VEGF) expression, and, in 2H11 cells, migration capabilities by wound healing assay. We have found an enhancement of cytotoxicity in 4T1 cells, whereas, in normal 2H11 cells, this effect was not statistically significant. The addition of TMD decreased the production of VEGF after PDT in 2H11 cell line. Our results reveal enhanced effectiveness of 5-ALA-PDT with TMD treatment compared to 5-ALA-PDT or TMD treatment alone. The addition of TMD may be a promising proceeding of the anti-tumor effect of PDT by decreasing the VEGF concentration in the culture medium. Further studies, including testing on different cell lines, are needed to confirm this assumption.

Vitamin D Metabolite Profile in Cholecalciferol- or Calcitriol-Supplemented Healthy and Mammary Gland Tumor-Bearing Mice

To analyze if the prometastatic activity of calcitriol (active vitamin D₃ metabolite), which was previously observed in a 4T1 breast cancer model, is also found in other breast cancers, and to assess the impact of various schemes of vitamin D supply, we used 4T1 and E0771 mouse metastatic and 67NR nonmetastatic cells in this study. BALB/c and C57BL/6 healthy and tumor-bearing mice were exposed to a control (1000 IU), low- (100 IU), and high- (5000 IU) vitamin D₃ diets. Additionally, from day 7 of tumor transplantation, the 1000 and 100 IU groups were gavaged with calcitriol (+cal). After 8 weeks of feeding, plasma levels of 25(OH)D₃, 24,25(OH)₂D₃, and 3-epi-25(OH)D₃ were significantly lower in calcitriol-treated and vitamin D-deficient groups than in the control, whereas the levels of all metabolites were increased in the 5000 IU group. The ratio of 25(OH)D₃:24,25(OH)₂D₃ was increased in both calcitriol-treated groups, whereas the ratio of 25(OH)D₃:3-epi-25(OH)D₃ was increased only in the 100 IU group but decreased in the 5000 IU group. In contrast to E0771, 4T1 lung metastasis was accelerated in all vitamin D-supplemented mice, as well as in the deficient group with an increased inflammatory response. 67NR tumor growth was transiently inhibited in the 1000 IU+cal group, but single metastases were observed in the 5000 and 100 IU groups. Based on the results, we conclude that various schemes of vitamin D supply and vitamin D deficiency led to similar metabolite profiles irrespective of the mice strain and tumor burden. However, depending on the type of breast cancer, different effects on tumor growth and metastasis were noticed.

Enhanced in vivo targeting of estrogen receptor alpha signaling in murine mammary adenocarcinoma by nilotinib/rosuvastatin novel combination

The development of resistance to endocrine therapy of estrogen receptor alpha (ERα)-positive breast cancer is inevitable, necessitating the introduction of alternative treatment strategies. Therefore, the current study was carried out to investigate the in vivo efficacy and tolerability of nilotinib/rosuvastatin novel combination against ERα-positive breast carcinoma. Results showed that treatment of tumor-bearing mice with nilotinib/rosuvastatin exerted a significant antitumor activity. Mechanistically, the combination treatment efficiently inhibited the in vivo ERα protein expression, whereas ERα mRNA levels were unaffected suggesting a posttranslational regulation. In addition, the combination treatment markedly downregulated the expression of two ERα downstream target genes: C3 and pS2 confirming the inhibition of ERα signaling in vivo. Further, nilotinib/rosuvastatin combination strongly induced apoptosis evidenced by a marked caspase-3 cleavage and downregulation of tumor nitric oxide levels. Moreover, histopathology showed significant declines in mitotic figures and tumor giant cells implying the in vivo capability of the combination treatment to interfere with cancer cell proliferation and persistence. Of note, the combination treatment abrogated nilotinib-induced hypercholesterolemia and did not adversely affect the liver function or body weight. Overall, the present study provided evidences that warrant further assessment of nilotinib/rosuvastatin combination as an alternative therapeutic modality for ERα-positive breast cancer.

EPA and DHA Fatty Acids Induce a Remodeling of Tumor Vasculature and Potentiate Docetaxel Activity

n-3 long chain Polyunsaturated Fatty Acids (n-3 LCPUFA) have been shown to improve the efficacy of conventional chemotherapies used for breast cancer treatment. In addition to their reported ability to increase the chemosensitivity of cancer cells, we hypothesized that n-3 LCPUFA could induce a remodeling of the vascular network in mammary tumors. A contrast-enhanced ultrasound method was used to monitor the vascular architecture during docetaxel treatment of mammary tumors in rats fed either a control or an n-3 LCPUFA-enriched diet (docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA)). The vascular network was remodeled in favor of smaller vessels (microvascularization), which represented 54% of the vasculature in n-3 LCPUFA tumors but only 26% in control tumors after 2 weeks of chemotherapy. Importantly, vascularization changes occurred both before and during docetaxel treatment. The density of smaller vessels quantified before chemotherapy was correlated with improved tumor size reduction by docetaxel treatment. Furthermore, transcript levels of the angiogenesis-specific genes epiregulin and amphiregulin were reduced by ~4.5- and twofold in tumors obtained from rats fed an n-3 LCPUFA-enriched diet compared to those of rats fed a control diet, respectively. Their expression levels were negatively correlated with tumor regression after chemotherapy. Taken together, this preclinical data strengthen the potential usefulness of n-3 LCPUFA as a complementary clinical strategy to improve drug efficiency via remodeling of the tumor vasculature.

Tumors Resistant to Checkpoint Inhibitors Can Become Sensitive after Treatment with Vascular Disrupting Agents

Immune therapy improves cancer outcomes, yet many patients do not respond. This pre-clinical study investigated whether vascular disrupting agents (VDAs) could convert an immune unresponsive tumor into a responder. CDF1 mice, with 200 mm³ C3H mammary carcinomas in the right rear foot, were intraperitoneally injected with combretastatin A-4 phosphate (CA4P), its A-1 analogue OXi4503, and/or checkpoint inhibitors (anti-PD-1, PD-L1, or CTLA-4 antibodies), administered twice weekly for two weeks. Using the endpoint of tumor growth time (TGT5; time to reach five times the starting volume), we found that none of the checkpoint inhibitors (10 mg/kg) had any effect on TGT5 compared to untreated controls. However, CA4P (100 mg/kg) or OXi4503 (5–50 mg/kg) did significantly increase TGT5. This further significantly increased by combining the VDAs with checkpoint inhibitors, but was dependent on the VDA, drug dose, and inhibitor. For CA4P, a significant increase was found when CA4P (100 mg/kg) was combined with anti-PD-L1, but not with the other two checkpoint inhibitors. With OXi4503 (50 mg/kg), a significant enhancement occurred when combined with anti-PD-L1 or anti-CTLA-4, but not anti-PD-1. We observed no significant improvement with lower OXi4503 doses (5–25 mg/kg) and anti-CTLA-4, although 30% of tumors were controlled at the 25 mg/kg dose. Histological assessment of CD4/CD8 expression actually showed decreased levels up to 10 days after treatment with OXi4503 (50 mg/kg). Thus, the non-immunogenic C3H mammary carcinoma was unresponsive to checkpoint inhibitors, but became responsive in mice treated with VDAs, although the mechanism remains unclear.

Ce6/Mn2+-chelated polydopamine@black-TiO2 nanoprobes for enhanced synergistic phototherapy and magnetic resonance imaging in 4T1 breast cancer

Black titanium dioxide (TiO2) nanoparticles have attracted great attention due to their application in photothermal therapy (PTT). However, single-mode phototherapy has the risk of recurrence, and the high-dose laser usually imposed to improve the PTT performance can bring a potential threat to security. Here, polydopamine (PDA)-coated black TiO2 (b-P25@PDA) nanoparticles with a core-shell structure were synthesized for enhanced PTT; then, synergistic phototherapy nanoprobes (b-P25@PDA-Ce6 (Mn)) were constructed by coupling chlorin e6 (Ce6) and chelating Mn2+ for simultaneous photodynamic therapy (PDT)/PTT and magnetic resonance (MR) imaging, in which a low-dose laser was used and imaging-guided phototherapy with high efficiency and high safety was achieved. The prepared nanoprobes showed high photothermal conversion efficiency (32.12%), high reactive oxygen generation and excellent MR imaging. In the 4T1 tumor-bearing nude mouse model, the tumors completely disappeared under the combination of PDT/PTT with a low-dose laser but were only partially inhibited by single PDT and single PTT. The current work developed a multifunctional black TiO2-based nanoprobe for enhanced synergistic PDT/PTT and MR imaging, which will be important for the safe and efficient visualized theranostics of cancers.

A strong CD8+ T cell-stimulating supramolecular hydrogel

The development of molecules with immune stimulatory properties is crucial for cancer immunotherapy. In this work, we combined two peptide-based molecules, tuftsin (TKPR) and Nap-GDFDFDY, to develop a novel self-assembling molecule Nap-GDFDFDYTKPR (Comp.3), which has strong CD8+ T cell stimulatory properties. Comp.3 could self-assemble into nanofibers and hydrogels, which significantly improved the stability of tuftsin against enzyme digestion. The nanofibers of Comp.3 enhanced the phagocytic activity of macrophages, promoted the maturation of DCs, and stimulated the expression of cytokines. In addition, it demonstrated an excellent anti-tumor efficacy in vivo by eliciting a strong CD8+ T immune response. Taken together, our observations revealed a powerful immune stimulating nanomaterial that is a promising compound for cancer immunotherapy.

Triggered All-Active Metal Organic Framework: Ferroptosis Machinery Contributes to the Apoptotic Photodynamic Antitumor Therapy

Nanoscale photodynamic therapy (PDT) is an appealing antitumor modality for which apoptosis is the major mechanism of toxicity induction. It was postulated that the highly reactive singlet oxygen in PDT could deplete glutathione (GSH) and activate ferroptosis, the extent to which could be further manipulated by a redox-responsive nanocarrier. To validate this, a disulfide-bearing imidazole ligand coordinated with zinc to form an all-active metal organic framework (MOF) nanocarrier where a photosensitizer (chlorin e6/Ce6) was encapsulated. Regardless of light irradiation, the Ce6-loaded nanocarrier caused the depletion of intracellular GSH via the disulfide-thiol exchange reaction in a murine mammary carcinoma cell line (4T1). The GSH depletion further caused the inactivation of glutathione peroxide 4 (GPX4) and the enhancement of cytotoxicity that was alleviated by ferroptosis inhibitors. The superior in vivo antitumor efficacy of the all-active nanocarrier was corroborated in a 4T1 tumor-bearing mice model regarding tumor growth suppression and animal survival rate. The coadministration of an iron chelator weakened the antitumor potency of the nanocarrier due to ferroptosis inhibition, which was supported by the fact of tumor growth upsurge and the recovered GPX4 activity. The current work highlights the contribution of ferroptotic machinery to antitumor PDT via an activatable, adaptable, all-active MOF nanocarrier.

Redox-Activated Porphyrin-Based Liposome Remote-Loaded with Indoleamine 2,3-Dioxygenase (IDO) Inhibitor for Synergistic Photoimmunotherapy through Induction of Immunogenic Cell Death and Blockage of IDO Pathway

Immunotherapy through stimulating the host immune system has emerged as a powerful therapeutic strategy for various malignant and metastatic tumors in the clinic. However, harnessing the immune system for cancer treatment often fails to obtain a durable response rate due to the poor immunogenicity and the strong immunosuppressive milieu in the tumor site. Herein, a redox-activated liposome was developed from the self-assembly of the porphyrin-phospholipid conjugate and coencapsulation of indoleamine 2,3-dioxygenase (IDO) inhibitor into the interior lumen via remote-loading for simultaneous induction of immunogenic cell death (ICD) and reversing of suppressive tumor microenvironment. The nanoparticle exhibited prolonged blood circulation and enhanced tumor accumulation in the 4T1 tumor-bearing mice after intravenous injection. The nanovesicle could render exponential activation of fluorescence signal and photodynamic therapy (PDT) activity (>100-fold) in response to the high level of intracellular glutathione after endocytosed by tumor cells, thereby achieving effective inhibition of tumor growth and reduced phototoxicity to normal tissues owing to the activatable design of the nanoparticle. More importantly, redox-activated PDT induced intratumoral infiltration of cytotoxic T lymphocytes by induction of ICD of tumor cells. After combining with the IDO inhibitor, the systemic antitumor immune response was further augmented. Hence, we believe that the present nanovesicle strategy has the potential for the synergistic immunotherapy of the metastatic cancers.

Liposomes of Quantum Dots Configured for Passive and Active Delivery to Tumor Tissue

The majority of developed and approved anticancer nanomedicines have been designed to exploit the dogma of the enhanced permeability and retention (EPR) effect, which is based on the leakiness of the tumor's blood vessels accompanied by impeded lymphatic drainage. However, the EPR effect has been under scrutiny recently because of its variable manifestation across tumor types and animal species and its poor translation to human cancer therapy. To facilitate the EPR effect, systemically injected NPs should overcome the obstacle of rapid recognition and elimination by the mononuclear phagocyte system (MPS). We hypothesized that circulating monocytes, major cells of the MPS that infiltrate the tumor, may serve as an alternative method for achieving increased tumor accumulation of NPs, independent of the EPR effect. We describe here the accumulation of liposomal quantum dots (LipQDs) designed for active delivery via monocytes, in comparison to LipQDs designed for passive delivery (via the EPR effect), following IV administration in a mammary carcinoma model. Hydrophilic QDs were synthesized and entrapped in functionalized liposomes, conferring passive ("stealth" NPs; PEGylated, neutral charge) and active (monocyte-mediated delivery; positively charged) properties by differing in their lipid composition, membrane PEGylation, and charge (positively, negatively, and neutrally charged). The various physicochemical parameters affecting the entrapment yield and optical stability were examined in vitro and in vivo. Biodistribution in the blood, various organs, and in the tumor was determined by the fluorescence intensity and Cd analyses. Following the treatment of animals (intact and mammary-carcinoma-bearing mice) with disparate formulations of LipQDs (differing by their lipid composition, neutrally and positively charged surfaces, and hydrophilic membrane), we demonstrate comparable tumor uptake of QDs delivered by the passive and the active routes (mainly by Ly-6C^hi monocytes). Our findings suggest that entrapping QDs in nanosized liposomal formulations, prepared by a new facile method, imparts superior structural and optical stability and a suitable biodistribution profile leading to increased tumor uptake of fluorescently stable QDs.

EZH2 Is Overexpressed in BRCA1-like Breast Tumors and Predictive for Sensitivity to High-Dose Platinum-Based Chemotherapy

PURPOSE

BRCA1-deficient breast cancers carry a specific DNA copy-number signature ("BRCA1-like") and are hypersensitive to DNA double-strand break (DSB) inducing compounds. Here, we explored whether (i) EZH2 is overexpressed in human BRCA1-deficient breast tumors and might predict sensitivity to DSB-inducing drugs; (ii) EZH2 inhibition potentiates cisplatin efficacy in Brca1-deficient murine mammary tumors.

EXPERIMENTAL DESIGN

EZH2 expression was analyzed in 497 breast cancers using IHC or RNA sequencing. We classified 370 tumors by copy-number profiles as BRCA1-like or non-BRCA1-like and examined its association with EZH2 expression. Additionally, we assessed BRCA1 loss through mutation or promoter methylation status and investigated the predictive value of EZH2 expression in a study population of breast cancer patients treated with adjuvant high-dose platinum-based chemotherapy compared with standard anthracycline-based chemotherapy. To explore whether EZH2 inhibition by GSK126 enhances sensitivity to platinum drugs in EZH2-overexpressing breast cancers we used a Brca1-deficient mouse model.

RESULTS

The highest EZH2 expression was found in BRCA1-associated tumors harboring a BRCA1 mutation, BRCA1-promoter methylation or were classified as BRCA1 like. We observed a greater benefit from high-dose platinum-based chemotherapy in BRCA1-like and non-BRCA1-like patients with high EZH2 expression. Combined treatment with the EZH2 inhibitor GSK126 and cisplatin decreased cell proliferation and improved survival in Brca1-deficient mice in comparison with single agents.

CONCLUSIONS

Our findings demonstrate that EZH2 is expressed at significantly higher levels in BRCA1-deficient breast cancers. EZH2 overexpression can identify patients with breast cancer who benefit significantly from intensified DSB-inducing platinum-based chemotherapy independent of BRCA1-like status. EZH2 inhibition improves the antitumor effect of platinum drugs in Brca1-deficient breast tumors in vivo.

Dietary baker's yeast sensitizes Ehrlich mammary adenocarcinoma to paclitaxel in mice bearing tumor

Baker's yeast, Saccharomyces cerevisiae, has been shown to sensitize a variety of breast cancer cell (BCC) lines to paclitaxel chemotherapy in vitro. The present study evaluated the ability of S. cerevisiae to sensitize BCCs to paclitaxel in animals bearing Ehrlich ascites carcinoma (EAC). Mice bearing EAC were intratumorally injected with dead S. cerevisiae (1x107 cells/ml) in the presence or absence of low- and high-dose paclitaxel [paclitaxel-L, 2 mg/kg body weight (BW) and paclitaxel-H, 10 mg/kg BW, respectively]. At 30 days post tumor inoculation, co-treatment with yeast plus paclitaxel-L showed improvements over paclitaxel-H alone, as measured by tumor weight (-64 vs. -53%), DNA damage (+79 vs. +62%), tumor cell apoptosis (+217 vs. +177%), cell proliferation (-56 vs. -42%) and Ki-67 marker (+95 vs. +40%). Histopathology and ultra-structural examinations showed that yeast plus paclitaxel-L enhanced apoptosis in EAC more than paclitaxel-H alone and caused comparable tumor necrosis. We conclude that baker's yeast may be used with low-dose chemotherapy to achieve the same potency as high-dose chemotherapy in mice bearing EAC. This suggests that baker's yeast may be an anticancer adjuvant and may have clinical implications for the treatment of breast cancer.

Identifying the murine mammary cell target of metformin exposure

The heterogeneity of breast cancer makes current therapies challenging. Metformin, the anti-diabetic drug, has shown promising anti-cancer activities in epidemiological studies and breast cancer models. Yet, how metformin alters the normal adult breast tissue remains elusive. We demonstrate metformin intake at a clinically relevant dose impacts the hormone receptor positive (HR+) luminal cells in the normal murine mammary gland. Metformin decreases total cell number, progenitor capacity and specifically reduces DNA damage in normal HR+ luminal cells, decreases oxygen consumption rate and increases cell cycle length of luminal cells. HR+ luminal cells demonstrate the lowest levels of mitochondrial respiration and capacity to handle oxidative stress compared to the other fractions, suggesting their intrinsic susceptibility to long-term metformin exposure. Uncovering HR+ luminal cells in the normal mammary gland as the major cell target of metformin exposure could identify patients that would most benefit from repurposing this anti-diabetic drug for cancer prevention/therapy purposes.

Effect of dihydroartemisinin on epithelial-to-mesenchymal transition in canine mammary tumour cells

Epithelial-to-mesenchymal transition (EMT) is a process by which epithelial cells acquire mesenchymal properties, generating metastases. Dihydroartemisinin (DHA) exhibits potent anti-cancer activities. CMTs is a potential suitable model for studies in human breast cancer research. In the present study, we separated DHA-untreated cells from CMTs cells to be a control group, the rest of the CMTs cells treated by DHA which were composed of three concentrations 5,10 as well as 20 μM. After that we cultivate the cells severally under the condition of 24, 48 and 72 h at 37 °C. CMTs cells were evaluated by Cell viability assay, Wound healing assay, Invasion assay and RT-PCR analysis for the expression of Slug, ZEB1, ZEB2 and Twist. Our results showed that DHA increased the inhibitory rate of CMTs cell and restrain TGF-β1-induced migration and invasion of cells in a time and concentration reliant manner efficaciously. Our result also show DHA inhibits the expression of Slug, ZEB1, ZEB2 and Twist at the mRNA in vitro, the media concentration DHA (10 μM) decreased the expression level of the Slug, ZEB1, ZEB2 mRNA significantly. In conclusion, DHA inhibits canine mammary tumours cells migration and invasiveness by regulating the expression of EMT-related genes.

Enhanced Drug Delivery by Nanoscale Integration of a Nitric Oxide Donor To Induce Tumor Collagen Depletion

Delivery of therapeutics into the solid tumor microenvironment is a major challenge for cancer nanomedicine. Administration of certain exogenous enzymes which deplete tumor stromal components has been proposed as a method to improve drug delivery. Here we present a protein-free collagen depletion strategy for drug delivery into solid tumors, based on activating endogenous matrix metalloproteinases (MMP-1 and -2) using nitric oxide (NO). Mesoporous silica nanoparticles (MSN) were loaded with a chemotherapeutic agent, doxorubicin (DOX) as well as a NO donor ( S-nitrosothiol) to create DN@MSN. The loaded NO results in activation of MMPs which degrade collagen in the tumor extracellular matrix. Administration of DN@MSN resulted in enhanced tumor penetration of both the nanovehicle and cargo (DOX), leading to significantly improved antitumor efficacy with no overt toxicity observed.

Quinic Acid-Conjugated Nanoparticles Enhance Drug Delivery to Solid Tumors via Interactions with Endothelial Selectins

Current nanoparticle (NP) drug carriers mostly depend on the enhanced permeability and retention (EPR) effect for selective drug delivery to solid tumors. However, in the absence of a persistent EPR effect, the peritumoral endothelium can function as an access barrier to tumors and negatively affect the effectiveness of NPs. In recognition of the peritumoral endothelium as a potential barrier in drug delivery to tumors, poly(lactic-co-glycolic acid) (PLGA) NPs are modified with a quinic acid (QA) derivative, synthetic mimic of selectin ligands. QA-decorated NPs (QA-NP) interact with human umbilical vein endothelial cells expressing E-/P-selectins and induce transient increase in endothelial permeability to translocate across the layer. QA-NP reach selectin-upregulated tumors, achieving greater tumor accumulation and paclitaxel (PTX) delivery than polyethylene glycol-decorated NPs (PEG-NP). PTX-loaded QA-NP show greater anticancer efficacy than Taxol or PTX-loaded PEG-NP at the equivalent PTX dose in different animal models and dosing regimens. Repeated dosing of PTX-loaded QA-NP for two weeks results in complete tumor remission in 40-60% of MDA-MB-231 tumor-bearing mice, while those receiving control treatments succumb to death. QA-NP can exploit the interaction with selectin-expressing peritumoral endothelium and deliver anticancer drugs to tumors to a greater extent than the level currently possible with the EPR effect.

G-Quadruplex-Based Nanoscale Coordination Polymers to Modulate Tumor Hypoxia and Achieve Nuclear-Targeted Drug Delivery for Enhanced Photodynamic Therapy

Photodynamic therapy (PDT) is a light-triggered therapy used to kill cancer cells by producing reactive oxygen species (ROS). Herein, a new kind of DNA nanostructure based on the coordination between calcium ions (Ca²⁺) and AS1411 DNA G quadruplexes to form nanoscale coordination polymers (NCPs) is developed via a simple method. Both chlorine e6 (Ce6), a photosensitizer, and hemin, an iron-containing porphyrin, can be inserted into the G-quadruplex structure in the obtained NCPs. With further polyethylene glycol (PEG) modification, we obtain Ca-AS1411/Ce6/hemin@pHis-PEG (CACH-PEG) NCP nanostructure that enables the intranuclear transport of photosensitizer Ce6 to generate ROS inside cell nuclei that are the most vulnerable to ROS. Meanwhile, the inhibition of antiapoptotic protein B-cell lymphoma 2 (Bcl-2) expression by AS1411 allows for greatly improved PDT-induced cell apoptosis. Furthermore, the catalase-mimicking DNAzyme function of G-quadruplexes and hemin in those NCPs could decompose tumor endogenous H₂O₂ to in situ generate oxygen so as to further enhance PDT by overcoming the hypoxia-associated resistance. This work develops a simple yet general method with which to fabricate DNA-based NCPs and presents an interesting concept of a nanoscale drug-delivery system that could achieve the intranuclear delivery of photosensitizers, the down-regulation of anti-apoptotic proteins, and the modulation of the unfavorable tumor microenvironment simultaneously for improved cancer therapy.

Unique Photochemo-Immuno-Nanoplatform against Orthotopic Xenograft Oral Cancer and Metastatic Syngeneic Breast Cancer

Sophisticated self-assembly may endow materials with a variety of unique functions that are highly desirable for therapeutic nanoplatform. Herein, we report the coassembly of two structurally defined telodendrimers, each comprised of hydrophilic linear PEG and hydrophobic cholic acid cluster as a basic amphiphilic molecular subunit. One telodendrimer has four added indocyanine green derivatives, leading to excellent photothermal properties; the other telodendrimer has four sulfhydryl groups designed for efficient intersubunit cross-linking, contributing to superior stability during circulation. The coassembled nanoparticle (CPCI-NP) possesses superior photothermal conversion efficiency as well as efficient encapsulation and controlled release of cytotoxic molecules and immunomodulatory agents. CPCI-NP loaded with doxorubicin has proven to be a highly efficacious combination photothermal/chemotherapeutic nanoplatform against orthotopic OSC-3 oral cancer xenograft model. When loaded with imiquimod, a potent small molecule immunostimulant, CPCI-NP is found to be highly effective against 4T1 syngeneic murine breast cancer model, particularly when photothermal/immuno-therapy is given in combination with PD-1 checkpoint blockade antibody. Such triple therapy not only eradicates the light-irradiated primary tumors, but also activates systemic antitumor immunoactivity, causing tumor death at light-unexposed distant tumor sites. This coassembled multifunctional, versatile, and easily scalable photothermal immuno-nanoplatform shows great promise for clinical translation.

The effect of naltrexone as a carboplatin chemotherapy-associated drug on the immune response, quality of life and survival of dogs with mammary carcinoma

The objective of this study was to evaluate the effect of low-dose naltrexone (LDN) as a carboplatin chemotherapy-associated drug in female dogs with mammary carcinoma in benign mixed tumors (MC-BMT) after mastectomy and to assess its association with quality of life and survival rates. Sixty female dogs were included in this study, all of which had histopathological diagnosis of MC-BMT and were divided into three groups: G1 (control), consisting of animals submitted only to mastectomy with or without regional metastasis; G2, composed of treated animals that did not present with metastasis; and G3, treated dogs that presented with metastasis. G2 and G3 were also subdivided according to the treatment administered: chemotherapy alone (MC-BMT(-) C/MC-BMT(+) C) or LDN and chemotherapy (MC-BMT(-) C+LDN/MC-BMT(+) C+LDN). All animals were subjected to clinical evaluation, mastectomy, peripheral blood lymphocyte immunophenotyping, beta-endorphin and met-enkephalin quantification, and evaluation of survival rates and quality of life scores. The results showed higher serum concentrations of beta-endorphin and met-enkephalin, fewer chemotherapy-related side effects, and better quality of life and survival rates in the LDN-treated groups than in LDN-untreated groups (P < 0.05). Evaluation of clinical and pathological parameters indicated a significant association between the use of LDN and both prolonged survival and enhanced quality of life. These results indicate that LDN is a viable chemotherapy-associated treatment in female dogs with MC-BMT, maintaining their quality of life and prolonging survival rates.

Anti-EGFR Affibodies with Site-Specific Photo-Cross-Linker Incorporation Show Both Directed Target-Specific Photoconjugation and Increased Retention in Tumors

A significant challenge for solid tumor treatment is ensuring that a sufficient concentration of therapeutic agent is delivered to the tumor site at doses that can be tolerated by the patient. Biomolecular targeting can bias accumulation in tumors by taking advantage of specific interactions with receptors overexpressed on cancerous cells. However, while antibody-based immunoconjugates show high binding to specific cells, their low dissociation constants ( KD) and large Stokes radii hinder their ability to penetrate deep into tumor tissue, leading to incomplete cell killing and tumor recurrence. To address this, we demonstrate the design and production of a photo-cross-linkable affibody that can form a covalent bond to epidermal growth factor receptor (EGFR) under near UV irradiation. Twelve cysteine mutations were created of an EGFR affibody and conjugated with maleimide-benzophenone. Of these only one exhibited photoconjugation to EGFR, as demonstrated by SDS-PAGE and Western blot. Next this modified affibody was shown to not only bind EGFR expressing cells but also show enhanced retention in a 3D tumor spheroid model, with minimal loss up to 24 h as compared to either unmodified EGFR-binding affibodies or nonbinding, photo-cross-linkable affibodies. Finally, in order to show utility of photo-cross-linking at clinically relevant wavelengths, upconverting nanoparticles (UCNPs) were synthesized that could convert 980 nm light to UV and blue light. In the presence of UCNPs, both direct photoconjugation to EGFR and enhanced retention in tumor spheroids could be obtained using near-infrared illumination. Thus, the photoactive affibodies developed here may be utilized as a platform technology for engineering new therapy conjugates that can penetrate deep into tumor tissue and be retained long enough for effective tumor therapy.

Near-Infrared Photoactivatable Nitric Oxide Donors with Integrated Photoacoustic Monitoring

Photoacoustic (PA) tomography is a noninvasive technology that utilizes near-infrared (NIR) excitation and ultrasonic detection to image biological tissue at centimeter depths. While several activatable small-molecule PA sensors have been developed for various analytes, the use of PA molecules for deep-tissue analyte delivery and monitoring remains an underexplored area of research. Herein, we describe the synthesis, characterization, and in vivo validation of photoNOD-1 and photoNOD-2, the first organic, NIR-photocontrolled nitric oxide (NO) donors that incorporate a PA readout of analyte release. These molecules consist of an aza-BODIPY dye appended with an aryl N-nitrosamine NO-donating moiety. The photoNODs exhibit chemostability to various biological stimuli, including redox-active metals and CYP450 enzymes, and demonstrate negligible cytotoxicity in the absence of irradiation. Upon single-photon NIR irradiation, photoNOD-1 and photoNOD-2 release NO as well as rNOD-1 or rNOD-2, PA-active products that enable ratiometric monitoring of NO release. Our in vitro studies show that, upon irradiation, photoNOD-1 and photoNOD-2 exhibit 46.6-fold and 21.5-fold ratiometric turn-ons, respectively. Moreover, unlike existing NIR NO donors, the photoNODs do not require encapsulation or multiphoton activation for use in live animals. In this study, we use PA tomography to monitor the local, irradiation-dependent release of NO from photoNOD-1 and photoNOD-2 in mice after subcutaneous treatment. In addition, we use a murine model for breast cancer to show that photoNOD-1 can selectively affect tumor growth rates in the presence of NIR light stimulation following systemic administration.

Activation of B-1 Cells Promotes Tumor Cell Killing in the Peritoneal Cavity

Metastatic cancer involving spread to the peritoneal cavity is referred to as peritoneal carcinomatosis and has a very poor prognosis. Activating the antitumor immune response in the characteristically immune-suppressive peritoneal environment presents a potential strategy to treat this disease. In this study, we show that a toll-like receptor (TLR) and C-type lectin receptor (CLR) agonist pairing of monophosphoryl lipid A (MPL) and trehalose-6,6'-dicorynomycolate (TDCM) effectively inhibits tumor growth and ascites development in a mouse model of aggressive mammary cancer-induced peritoneal carcinomatosis. MPL/TDCM treatment similarly inhibited peritoneal EL4 tumor growth and ascites development. These effects were not observed in mice lacking B cells or mice lacking CD19, which are deficient in B-1a cells, an innate-like B-cell population enriched in the peritoneal cavity. Remarkably, adoptive transfer of B-1a cells, but not splenic B cells from WT mice, restored MPL/TDCM-induced protection in mice with B-cell defects. Treatment induced B-1 cells to rapidly produce high levels of natural IgM reactive against tumor-associated carbohydrate antigens. Consistent with this, we found significant deposition of IgM and C3 on peritoneal tumor cells as early as 5 days post-treatment. Mice unable to secrete IgM or complement component C4 were not protected by MPL/TDCM treatment, indicating tumor killing was mediated by activation of the classical complement pathway. Collectively, our findings reveal an unsuspected role for B-1 cell-produced natural IgM in providing protection against tumor growth in the peritoneal cavity, thereby highlighting potential opportunities to develop novel therapeutic strategies for the prevention and treatment of peritoneal metastases. SIGNIFICANCE: This work identifies a critical antitumor role for innate-like B cells localized within the peritoneal cavity and demonstrates a novel strategy to activate their tumor-killing potential.See related commentary by Tripodo, p. 5.

Anti‑cancer effects of fisetin on mammary carcinoma cells via regulation of the PI3K/Akt/mTOR pathway: In vitro and in vivo studies

Fisetin, a natural flavonoid found in a variety of edible and medical plants, has been suggested to inhibit the proliferation of various tumor cells and to induce apoptosis. However, the effects of fisetin on breast cancer have rarely been reported and the underlying mechanism is still undefined. The present study explored the anti‑cancer effects of fisetin on mammary carcinoma cells and the underlying mechanisms. Following treatment with fisetin, viability of 4T1, MCF‑7 and MDA‑MB‑231 cells were measured by MTT assay. The inhibitory effects of fisetin on proliferation, migration and invasion were evaluated in 4T1 cells using proliferation array, wound‑healing assay, and HUV‑EC‑C‑cell barrier based on electrical cell‑substrate impedance sensing platform. Cell apoptosis was analyzed by flow cytometry, and western blotting analysis was performed to identify target molecules. A 4T1 orthotopic mammary tumor model was used to assess the fisetin‑inhibition on tumor growth in vivo. Test kits were used to examine the liver and kidney function of tumor‑bearing mice. The results suggest that fisetin suppressed the proliferation of breast cancer cells, suppressed the metastasis and invasiveness of 4T1 cells, and induced the apoptosis of 4T1 cells in vitro. The potent anti‑cancer effect of fisetin was associated with the regulation of the phosphatidylinositol‑3‑kinase/protein kinase B/mammalian target of rapamycin pathway. In vivo experiments demonstrated that fisetin suppressed the growth of 4T1 cell‑derived orthotopic breast tumors and enhanced tumor cell apoptosis, and the evaluated alanine amino transferase and aspartate amino transferase levels in serum of tumor‑bearing mice suggested that fisetin may lead to side effects on liver biochemical function. The present study confirms that fisetin exerted an anti‑mammary carcinoma effect. However, in vivo experiments also revealed that fisetin had low solubility and low bioavailability. Further investigation is required to determine the clinical value of fisetin.

The Effects of Combinatorial Genistein and Sulforaphane in Breast Tumor Inhibition: Role in Epigenetic Regulation

Dietary compounds that possess the properties of altering epigenetic processes are gaining popularity as targets for cancer prevention studies. These compounds when administered at optimal concentrations and especially in combination can have enhanced effects in cancer prevention or therapy. It is important to study the interaction of two or more compounds in order to assess their role in enhancing prevention. Genistein (GEN), found in soy, has been extensively studied for its role as an epigenetic modifier especially as a DNA methyltransferase (DNMT) inhibitor and sulforaphane (SFN), found in cruciferous vegetables, is known as a histone deacetylase (HDAC) inhibitor. However, very little is known about the effects of these two compounds in conjunction in breast cancer prevention or therapy. In our current study, we determined that, at certain doses, the compounds have synergistic effects in decreasing cellular viability of breast cancer cell lines. Our results indicate that the combination of GEN and SFN is much more effective than their single doses in increasing the rate of apoptosis and lowering the colony forming potential of these cells. We determined that these compounds inhibit cell cycle progression to G2 phase in MDA-MB-231 and G1 phase in MCF-7 breast cancer cell lines. Additionally, we determined that the combination is effective as an HDAC and histone methyltransferase (HMT) inhibitor. Furthermore, we demonstrated that this combination downregulates the levels of HDAC2 and HDAC3 both at the mRNA and protein levels. We also found that these compounds have the potential to downregulate KLF4 levels, which plays an important role in stem cell formation. The combination of GEN and SFN is also effective in downregulating hTERT levels, which is known to be activated when KLF4 binds to its promoter region. Our hypothesis is further strengthened by in vivo studies, where the combination is administered to transgenic mice in the form of genistein and SFN-enriched broccoli sprouts. We have demonstrated that the combination is more effective in preventing or treating mammary cancer via extending tumor latency and reducing tumor volumes/sizes than either of these dietary components administered alone. These results are consistent with our in vitro study suggesting potential preventive and therapeutic effects of this novel dietary combinatorial approach against breast cancer.

Autophagy promotes the survival of dormant breast cancer cells and metastatic tumour recurrence

Cancer recurrence after initial diagnosis and treatment is a major cause of breast cancer (BC) mortality, which results from the metastatic outbreak of dormant tumour cells. Alterations in the tumour microenvironment can trigger signalling pathways in dormant cells leading to their proliferation. However, processes involved in the initial and the long-term survival of disseminated dormant BC cells remain largely unknown. Here we show that autophagy is a critical mechanism for the survival of disseminated dormant BC cells. Pharmacologic or genetic inhibition of autophagy in dormant BC cells results in significantly decreased cell survival and metastatic burden in mouse and human 3D in vitro and in vivo preclinical models of dormancy. In vivo experiments identify autophagy gene autophagy-related 7 (ATG7) to be essential for autophagy activation. Mechanistically, inhibition of the autophagic flux in dormant BC cells leads to the accumulation of damaged mitochondria and reactive oxygen species (ROS), resulting in cell apoptosis.

The effect of size and polymer architecture of doxorubicin-poly(ethylene) glycol conjugate nanocarriers on breast duct retention, potency and toxicity

Although systemic administration of chemotherapeutic agents is routinely used for treating invasive breast cancer, the only therapeutic options for ductal carcinoma in situ (DCIS) are surgery and radiation. Treating DCIS by delivering drugs locally to the affected milk duct offers significant advantages over systemic administration, including reduced systemic and breast toxicities, as well as a greatly reduced need for surgery and radiation. In this study, mammary gland retention and toxicity of intraductally administered poly(ethylene) glycol-doxorubicin (PEG-DOX) polymeric conjugate nanocarriers of varying molecular sizes and architectures were investigated. Nanocarriers were formed by conjugating one or more copies of doxorubicin to PEG polymers, of varying molecular weights (5, 10, 20, and 40 kDa) and architectures (linear, four-arm and eight-arm). Cytotoxicity against MCF7 cells, a human breast cancer cell line, was assessed, and IC₅₀ values were calculated. The nanocarriers were intraductally administered into the mammary glands of female retired breeder Sprague-Dawley rats. Whole body images were captured using in vivo optical imaging, and changes in ductal structure as well local inflammation were monitored. Fluorescence intensities were monitored, over time, to evaluate nanocarrier mammary gland retention half-lives (t_1/2). The IC₅₀ values of PEG-DOX nanocarriers against MCF7 cells were 40 kDa PEG-(DOX)₄ (1.23 μM) < 5 kDa PEG-DOX (1.76 μM) < 40 kDa PEG-(DOX)₈ (3.49 μM) < 10 kDa PEG-DOX (3.86 μM) < 20 kDa PEG-DOX (8.96 μM) < 40 kDa PEG-DOX (18.11 μM), whereas the IC₅₀ of free DOX was only 0.14 μM. The t_1/2 of linear 5, 20, and 40 kDa nanocarriers were 2.2 ± 0.3, 3.6 ± 0.6, and 13.1 ± 3.4 h, whereas the retention t_1/2 of 4- and 8-arm 40 kDa nanocarriers were 14.9 ± 5.6 h and 11.9 ± 2.9 h, respectively. The retention t_1/2 of free doxorubicin was 2.0 ± 0.4 h, which was significantly shorter than that of the linear and branched 40 kDa PEG-DOX nanocarriers. Increased molecular weight and decreased branching both demonstrated a strong correlation to enhanced mammary gland retention. Intraductally administered free doxorubicin resulted in ductal damage, severe inflammation and generation of atypical cell neoplasms, whereas PEG-DOX nanocarriers induced only minor and transient inflammation (i.e., damaged epithelial cells and detached cellular debris). The 40 kDa 4-arm PEG-DOX nanocarrier demonstrated the longest ductal retention half-life, the lowest IC₅₀ (i.e., most potent), and minimal ductal damage and inflammation. The current results suggest that PEG-DOX nanocarriers with prolonged ductal retention may present the best option for intraductal treatment of DCIS, due to their low local toxicity and potential for sustained therapeutic effect.

Anti-inflammatory and anti-tumor effects of α-l-guluronic acid (G2013) on cancer-related inflammation in a murine breast cancer model

Cancer-related inflammation (CRI) is associated with the malignant progression of several cancer types. Targeting these pathways is a novel promising strategy for cancer prevention and treatment. In this present study, we evaluated the efficacy of ?-l-guluronic acid (ALG), a potent anti-inflammatory agent on breast cancer-related inflammation both in vitro and in vivo conditions. Our results indicated that ALG can effectively inhibit the CRI and tumor-promoting mediators (COX-2, MMP2, MMP9, VEGF and proinflammatory cytokines) without direct toxic effects on the cells. Moreover, it was found that, ALG can effectively inhibit the tumor cell adhesion to extracellular matrix, seeding in implantation tissue, reduce accumulation of immunosuppressive and inflammatory cells in tumor-bearing mice. These findings were associated with decreased tumor growth, metastasis, angiogenesis and prolonged mice survival. In conclusion, our data provide a cellular and molecular justification for the use of nonsteroidal anti-inflammatory drugs (NSAIDs) in treating cancer and imply the potential anti-tumor activity of ALG therapy via inhibition of CRI. These findings could lead to the establishment of novel NSAID-based cancer therapy in the near future and open a new horizon for cancer treatment.

Differential Gene Regulation and Tumor-Inhibitory Activities of Alpha-, Delta-, and Gamma-Tocopherols in Estrogen-Mediated Mammary Carcinogenesis

Despite experimental evidence elucidating the antitumor activities of tocopherols, clinical trials with α-tocopherol (α-T) have failed to demonstrate its beneficial effects in cancer prevention. This study compared the chemopreventive efficacy of individual tocopherols (α-, δ-, and γ-T) and a γ-T-rich tocopherol mixture (γ-TmT) in the August-Copenhagen Irish (ACI) rat model of estrogen-mediated mammary cancer. Female ACI rats receiving 17β-estradiol (E2) implants were administered with 0.2% α-T, δ-T, γ-T, or γ-TmT for 30 weeks. Although α-T had no significant effects on mammary tumor growth in ACI rats, δ-T, γ-T, and γ-TmT reduced mammary tumor volume by 51% (P < 0.05), 60% (P < 0.01), and 59% (P < 0.01), respectively. Immunohistochemical analysis revealed that δ-T, γ-T, and γ-TmT reduced levels of the cell proliferation marker, proliferating cell nuclear antigen, in the rat mammary tumors. To gain further insight into the biological functions of different forms of tocopherols, RNA-seq analysis of the tumors was performed. Treatment with γ-T induced robust gene expression changes in the mammary tumors of ACI rats. Ingenuity Pathway Analysis identified "Cancer" as a top disease pathway and "Tumor growth" and "Metastasis" as the top signaling pathways modulated by γ-T. Although the results need further functional validation, this study presents an unbiased attempt to understand the differences between biological activities of individual forms of tocopherols at the whole transcriptome level. In conclusion, δ-T and γ-T have superior cancer preventive properties compared to α-T in the prevention of estrogen-mediated mammary carcinogenesis. Cancer Prev Res; 10(12); 694-703. ©2017 AACR.

Doubling Down on BRCA-Mutated Cancer

Immunotherapy is changing the landscape of cancer treatment. Nonetheless, not all malignancies respond, possibly due to low mutational load. Recent work in a TP53^-/-BRCA1-mutant murine breast cancer model indicates that double blockade with two immune checkpoint inhibitors increases the number of tumor-infiltrating lymphocytes and overall survival after DNA damaging chemotherapy, whereas single blockade does not. These findings suggest an approach to enhance the impact of immune checkpoint blockade in BRCA-mutated tumors.

In Vitro Validation of the Hippo Pathway as a Pharmacological Target for Canine Mammary Gland Tumors

Canine mammary tumors (CMTs) are the most common neoplasms in intact female dogs. Some clinical and molecular similarities between certain CMT subtypes and breast cancer make them a potential model for the study of the human disease. As misregulated Hippo signaling is thought to play an important role in breast cancer development and also occurs in CMTs, we sought to determine if Hippo represents a valid pharmacological target for the treatment of CMTs. Six CMT cell lines were assessed for their expression of the Hippo pathway effectors YAP and TAZ and for their sensitivity to verteporfin, an inhibitor of YAP-mediated transcriptional coactivation. Four cell lines that expressed YAP (CMT-9, -12, -28, -47) were found to be very sensitive to verteporfin treatment, which killed the cells through induction of apoptosis with ED50 values of 14-79 nM. Conversely, two YAP-negative cell lines (CF-35, CMT-25) were an order of magnitude more resistant to verteporfin. Verteporfin suppressed the expression of YAP/TAZ target genes, particularly CYR61 and CTGF, which play important roles in breast cancer development. Verteporfin was also able to inhibit cell migration and anchorage-independent growth. Likewise, verteporfin efficiently suppressed tumor cell invasiveness in the CMT-28 and -47 lines, but not in CF-35 cells. Together, our findings provide proof of principle that pharmacological targeting of the Hippo pathway compromises the viability and attenuates the malignant behavior of CMT cells. These results will serve as the basis for the development of novel chemotherapeutic approaches for CMTs that could translate to human medicine.