Mammary Cancer Cells Research Articles

Long-term exposure to BAY2416964 reduces proliferation, migration and recapitulates transcriptional changes induced by AHR loss in PyMT-induced mammary tumor cells.

The aryl hydrocarbon receptor (AHR) is a ligand activated transcription factor which in certain cancer types drives pro-survival processes that facilitate tumorigenesis, malignant cell migration, invasion, and metastasis. Much of AHR's pro-tumorigenic action is due to its activation by the oncometabolite, kynurenine. Because of this AHR antagonists are being actively investigated as new anti-tumor therapy. In this study we compared the effects of treatment with the AHR antagonists, BAY2416964 and GNF351, to that of AHR knockout in PyMT murine mammary cancer cells. BAY2416964 and GNF351 effectively inhibited kynurenine-dependent increases in Cyp1a1 and Cyp1b1 mRNA levels. CRISPR/Cas9-generated PyMT AhrKO cells exhibited reduced cell proliferation compared with controls, but treatment with 1 μM BAY2416964 for 96h had no effect on the proliferation of wildtype cells. To further examine the differences between AHR knockout and short term BAY2416964, we generated long-term BAY2416964 (LT-BAY) cells by exposing wildtype cells to 1 μM BAY2416964 for at least 6 weeks. Similar to AhrKO cells, LT-BAY cells exhibited reduced cell proliferation and migration compared with wildtype cells. No differentially expressed genes (DEGs) were identified in wildtype cells exposed to 1 μM BAY2416964 for 24h; however, 46.4% of DEGs overlapped between AhrKO and LT-BAY cells including gene regulated cell proliferation. Our data reveal long-term pharmacological inhibition of AHR by BAY2416964 closely resembles AHR loss in a mouse model of breast cancer.

A new vision of photothermal therapy assisted with gold nanorods for the treatment of mammary cancers in adult female rats.

Over the past decade, the therapeutic landscape has markedly changed for patients with breast cancers (BCs), yet few studies have evaluated the power of the photothermal therapy (PTT) technique. The present study aimed to assess the potency of 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary cancer treatment with this technique. In total, forty-two adult virgin female Wistar rats were categorized into seven groups, negative control, polyvinylpyrrolidone-capped gold nanorods (PVP-AuNRs) positive control (400 μL per rat ∼ 78 ppm), NIR laser irradiation 808 nm positive control with an intensity of (808 nm NIR CW diode laser, 200 mW cm-2 for 5 min), DMBA-treatment, DMBA-induced mammary cancer group treated with polyvinylpyrrolidone-capped gold nanorods, DMBA-induced mammary cancer group treated with NIR laser irradiation, and DMBA-induced mammary cancer group treated with polyvinylpyrrolidone-capped gold nanorods and NIR laser irradiation. Treatment with polyvinylpyrrolidone-capped gold nanorods and/or NIR laser irradiation was performed after three weeks of DMBA-induced mammary cancer. The mammary tumor lesions in the rat model induced with DMBA are highly invasive. Synthesis and characterization of gold nanorods (AuNRs) with an aspect ratio ranging from 2.8 to 3 were employed to validate the nanostructure and polyvinylpyrrolidone capping and their stability in absorbing near-infrared light. As a result, the therapy strategy, DMBA + PVP-AuNRs + NIR, effectively treated the tumor and halted its growth. The mammary glands were dissected and subjected to biochemical analysis for serum and tissue. Our treatment technique improved the histological aspects of mammary cancer in various forms of mammary cancer detected. Immuno-histochemical localization and TEM images supported these results reflecting the efficacy of this technique. Finally, our findings uncover for the first time the revolutionary effect of the PTT strategy using PVP-capped AuNRs in selectively destroying mammary cancer cells in rats.

Spectral fingerprinting of cellular lipid droplets using stimulated Raman scattering microscopy and chemometric analysis.

Hyperspectral stimulated Raman scattering (SRS) microscopy is a powerful method for direct visualisation and compositional analysis of cellular lipid droplets. Here we report the application of spectral phasor analysis as a convenient method for the segmentation of lipid droplets using the hyperspectral SRS spectrum in the high wavenumber and fingerprint region of the spectrum. Spectral phasor analysis was shown to discriminate six fatty acids based on vibrational spectroscopic features in solution. The methodology was then applied to studying fatty acid metabolism and storage in a mammalian cancer cell model and during drug-induced steatosis in a hepatocellular carcinoma cell model. The accumulation of fatty acids into cellular lipid droplets was shown to vary as a function of the degree of unsaturation, whilst in a model of drug-induced steatosis, the detection of increased saturated fatty acid esters was observed. Taking advantage of the fingerprint and high wavenumber regions of the SRS spectrum has yielded a greater insight into lipid droplet composition in a cellular context. This approach will find application in the label-free profiling of intracellular lipids in complex disease models.

Inhalable dry powders of microRNA-laden extracellular vesicles prepared by thin-film freeze-drying

Extracellular vesicles (EVs) are endogenous vesicles that comprise a variety of submicron vesicular structures. Among these, exosomes have been widely investigated as delivery systems for small and large molecules. Herein, the thin-film freeze-drying technology was utilized to engineer aerosolizable dry powders of miR-335-laden induced EVs (iEV-335) generated in B cells for potential delivery into the lung to treat primary lung cancer and/or pulmonary metastases. The size distribution, structure, and morphology of iEV-335 were preserved after they were subjected to thin-film freeze-drying with the proper excipients. Importantly, iEV-335, in liquid or reconstituted from thin-film freeze-dried powders, were equally effective in downregulating SOX4 gene expression in LM2 human triple-negative mammary cancer cells. The iEV-335 dry powder compositions showed mass median aerodynamic diameters (MMAD) of around 1.2 µm with > 60 % of the emitted doses had an MMAD of ≤ 3 µm, indicating that the powders can potentially achieve efficient deposition within the alveolar region following oral inhalation, which is desirable for treatment of primary lung cancer and pulmonary metastases. Overall, it is concluded that it is feasible to apply thin-film freeze-drying to prepare aerosolizable dry powders of iEVs for pulmonary delivery.

A naturally occurring polyacetylene isolated from carrots promotes health and delays signatures of aging

To ameliorate or even prevent signatures of aging in ultimately humans, we here report the identification of a previously undescribed polyacetylene contained in the root of carrots (Daucus carota), hereafter named isofalcarintriol, which we reveal as potent promoter of longevity in the nematode C. elegans. We assign the absolute configuration of the compound as (3 S,8 R,9 R,E)-heptadeca-10-en-4,6-diyne-3,8,9-triol, and develop a modular asymmetric synthesis route for all E-isofalcarintriol stereoisomers. At the molecular level, isofalcarintriol affects cellular respiration in mammalian cells, C. elegans, and mice, and interacts with the α-subunit of the mitochondrial ATP synthase to promote mitochondrial biogenesis. Phenotypically, this also results in decreased mammalian cancer cell growth, as well as improved motility and stress resistance in C. elegans, paralleled by reduced protein accumulation in nematodal models of neurodegeneration. In addition, isofalcarintriol supplementation to both wild-type C57BL/6NRj mice on high-fat diet, and aged mice on chow diet results in improved glucose metabolism, increased exercise endurance, and attenuated parameters of frailty at an advanced age. Given these diverse effects on health parameters in both nematodes and mice, isofalcarintriol might become a promising mitohormesis-inducing compound to delay, ameliorate, or prevent aging-associated diseases in humans.

Abstract LB_C10: An orally available small molecule inhibitor for synthetic lethal targeting of MYC expressing tumors

Abstract The potential for synthetic lethality occurs when the same oncogenic events that promote carcinogenesis, also create vulnerabilities for cancer cells. Targeting cancers with these vulnerabilities, but not resident normal tissues, is the promise of synthetic lethal therapies. The compound LC30 is a potent and orally bioavailable compound that is synthetic lethal with deregulated MYC. No off-target liabilities have been demonstrated by kinome and safety profiling and long-term treatment is well tolerated by rodents and canines. LC30 is active against a wide spectrum of cell line xenografts derived from both liquid and solid cancers, including B and T cell malignancies, lung, colon, gastric, mammary and liver cancer cell lines, with efficacy that correlates with levels of MYC. Experiments aimed at unlocking the key to LC30’s synthetic lethality have revealed that LC30 is active in both resting cells and during cell division, so it is not simply an anti-mitotic compound. In resting cells, LC30 disrupts golgi structure, a phenotype that possibly relates to MYC control of centrosomal gene expression. Anti-angiogenic effects are observed in xenografts and have been confirmed using in vitro assays of endothelial cell migration and tubule formation. We speculate that the golgi phenotype and resulting faulty trafficking of secretory vesicles containing pro-angiogenic factors may underly the vascular phenotype. In dividing cells, LC30 potently deregulates the positioning of the chromosomal passenger protein complex (CPPC), a mitotic complex comprised of a catalytic subunit, Aurora B kinase (AURKB), the scaffolding protein inner centromere protein (INCENP) as well as survivin and borealin. The CPPC is dynamically relocated during mitotic progression so that AURKB activity can be localized to specific locations where activity is required. The phenotypic effects of LC30 treatment are consistent with this compound functioning as an inhibitor of the localization, but not catalytic activity of the CPPC. This includes the induction of multipolar spindles, micronuclei and polyploidy, leading to mitotic arrest and both mitotic and post-mitotic apoptosis. This unique mode-of-action, to disrupt CPPC passage in the mitotic cell, is a key component of the MYC synthetic lethality as cells without MYC overexpression do not develop multipolar spindles, lethal polyploidy and apoptose with treatment. LC30 represents a new class of anticancer compound that is a non-kinase, synthetic lethal inhibitor that unlocks MYC-induced vulnerabilities in cancer cells. Citation Format: Qiong Shi, Ting Zhang, Julia Kalashova, Jinhua Li, Chenglu Yang, Hongmei Li, Xiaohu Zhou, Yan Long, Yidan Xia Abuliezi, Gang Lv, Duo Yu, Shenqiu Zhang, Jing Zhang, Thaddeus D Allen, Hong Liu, Dun Yang. An orally available small molecule inhibitor for synthetic lethal targeting of MYC expressing tumors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr LB_C10.

VEGF-C-expressing TAMs rewire the metastatic fate of breast cancer cells

The expression of pro-lymphangiogenic VEGF-C in primary tumors is associated with sentinel lymph node metastasis in most solid cancer types. However, the impact of VEGF-C on distant organ metastasis remains unclear. Perivascular tumor-associated macrophages (TAMs) play a crucial role in guiding hematogenous spread of cancer cells by establishing metastatic pathways within the tumor microenvironment. This process supports breast cancer cell intravasation and metastatic dissemination. We show here that VEGF-C-expressing TAMs reduce the dissemination of mammary cancer cells to the lungs while concurrently increasing lymph node metastasis. These TAMs express podoplanin and interact with normalized tumor blood vessels expressing VEGFR3. Moreover, clinical data suggest inverse association between VEGF-C-expressing TAMs and breast cancer malignancy. Thus, our study elucidates the paradoxical role of VEGF-C-expressing TAMs in redirecting cancer cells to preferentially disseminate to lymph nodes rather than to lungs, partially achieved by normalizing tumor blood vessels and promoting lymphangiogenesis.

Abstract B041: Defining the Determinants of Immune Response in DNA Homologous Recombination Deficient Tumors

Abstract Immune checkpoint blockade (ICB) has shown unprecedented success in improving clinical outcomes for numerous cancer patients, but many patients still fail to respond to treatment. Studies have demonstrated that the tumor microenvironment, tumor mutational burden, and patient DNA Damage Repair (DDR) deficiency may play a key role in determining response to ICB. To better characterize this and define key determinants of ICB response, we created an isogenic knockout BRCA2 in a murine 4T1 metastatic TNBC background to model these differential clinical responses and to assess how these tumor-intrinsic programs influence the tumor immune microenvironment to poise tumors for immunotherapy response. Differential immune landscapes were found via scRNAseq at baseline and with ICB driven by tumor DDR status with notable differences in the myeloid compartment and CXCR3-expressing T cell, NK, pDC, DCs, and plasma cells. Differential expression and interferon stimulated gene (ISG) metagene analysis showed notable differences in ISG expression in DDR-deficient samples at baseline, particularly in clusters containing monocytes and macrophages. Additionally, differential expression of CXCL10 in monocytes/macrophages and assessment of ligand-receptor interactions by CellChat similarly showed enhanced contribution CXCL10-CXCR3. Parallel bulk RNAseq analysis showed increased production of T cell trafficking chemokines that would poise the tumor for response to ICB. Our lab established a genetic interferon reporter system to measure both tumor intrinsic interferon-driven inflammation in cis and in trans with tumor associated macrophages, which enables multidimensional tracking of bidirectional signaling between tumor cells and macrophages by flow. This system enabled screening of inhibitors and tumor knockout cell lines to identify that tumor-intrinsic cGAS/STING and IFNb1 reinforce production of tumor and myeloid CXCL10/11 to poise the tumor for response to ICB. Further assessment of tumor cell lines via cellular fractionation experiments identified the presence of both gDNA and R-loops in the cytoplasm of BRCA2-mutant mammary cancer cell lines that may be detected as damage associated molecular patterns by tumor cells or myeloid cells in the tumor bed. Future studies aim at validating this DDR-driven production of IFNb1 as a driver of T cell chemokines in vivo; tumor-intrinsic knockout of IFNb1 and other T cell promoting chemokines (CXCL10/11/CCL5) to assess tumor or myeloid driven nature of this response to ICB and depletion of myeloid cells are being performed in parallel to assess contribution of tumor and myeloid cells, respectively. Taken together, our results have important implications for understanding the key drivers of ICB response in the tumor microenvironment and how patient-intrinsic mutations differentially poise the microenvironment for immunotherapy response. Citation Format: Natalie Vaninov, Robert Samstein. Defining the Determinants of Immune Response in DNA Homologous Recombination Deficient Tumors [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr B041.

Differentiation-inducing factor-1 reduces lipopolysaccharide-induced vascular cell adhesion molecule-1 by suppressing mTORC1-S6K signaling in vascular endothelial cells

AimsDifferentiation-inducing factor-1 (DIF-1), a compound in Dictyostelium discoideum, exhibits anti-cancer effects by inhibiting cell proliferation and motility of various mammalian cancer cells in vitro and in vivo. In addition, DIF-1 suppresses lung colony formation in a mouse model, thus impeding cancer metastasis. However, the precise mechanism underlying its anti-metastatic effect remains unclear. In the present study, we aim to elucidate this mechanism by investigating the adhesion of circulating tumor cells to blood vessels using in vitro and in vivo systems. Main methodsMelanoma cells (1.0 × 105 cells) were injected into the tail vein of 8-week-old male C57BL/6 mice after administration of DIF-1 (300 mg/kg per day) and/or lipopolysaccharide (LPS: 2.5 mg/kg per day). To investigate cell adhesion and molecular mechanisms, cell adhesion assay, western blotting, immunofluorescence staining, and flow cytometry were performed. Key findingsIntragastric administration of DIF-1 suppressed lung colony formation. DIF-1 also substantially inhibited the adhesion of cancer cells to human umbilical vein endothelial cells. Notably, DIF-1 did not affect the expression level of adhesion-related proteins in cancer cells, but it did decrease the expression of vascular cell adhesion molecule-1 (VCAM-1) in human umbilical vein endothelial cells by suppressing its mRNA-to-protein translation through inhibition of mTORC1-p70 S6 kinase signaling. SignificanceDIF-1 reduced tumor cell adhesion to blood vessels by inhibiting mTORC1-S6K signaling and decreasing the expression of adhesion molecule VCAM-1 on vascular endothelial cells. These findings highlight the potential of DIF-1 as a promising compound for the development of anti-cancer drugs with anti-metastatic properties.

Doxorubicin as a Potential Treatment Option in Canine Mammary Tumors.

Canine mammary tumors represent one of the leading malignant pathologies in female dogs, displaying the importance of efficient therapeutic findings, besides the golden-standard surgery, able to limit the development of the disease. Studies in human cancers demonstrated that Doxorubicin presents a good effect in different biological processes like apoptosis, autophagy, the cell cycle, cell invasion, and the epithelial-to-mesenchymal transition. This study followed the effects of Doxorubicin on two canine mammary cancer cell lines P114 and CMT-U27. Doxorubicin treatment in both cell lines shows an inhibitory effect in cell proliferation and an alteration in expression of the EMT-related genes. The obtained results provide valuable information for revealing the link between Doxorubicin, phenotypic changes, and proliferation dynamics in canine mammary tumor models.

Anti-tumor activity of a recombinant measles virus against canine lung cancer cells

Canine primary lung cancer with metastasis has a poor prognosis with no effective treatment. We previously generated a recombinant measles virus (MV) that lost binding affinity to a principal receptor, SLAM, to eliminate its virulence as a new cancer treatment strategy. The virus, rMV-SLAMblind, targets nectin-4, recently listed as a tumor marker, and exerts antitumor activity against nectin-4-positive canine mammary cancer and urinary bladder transitional cell carcinoma cells. However, the effectivity of rMV-SLAMblind for other types of canine cancers is still unknown. Here we evaluated the antitumor effect of rMV-SLAMblind to canine lung cancer. Nectin-4 is expressed on three canine lung cancer cell lines (CLAC, AZACL1, AZACL2) and rMV-SLAMblind was able to infect these cell lines. CLAC cells showed reduced cell viability after virus infection. In the CLAC xenograft nude mouse model, intratumoral administration of rMV-SLAMblind significantly suppressed tumor growth. In rMV-SLAMblind-treated mice, natural killer cells were activated, and Cxcl10 and Il12a levels were significantly increased in comparison with levels in the control group. In addition, the depletion of NK cells reduced the anti-tumor effect. To understand difference in efficacy among canine lung cancer cell lines, we compared virus growth and gene expression pattern after virus treatment in the three canine lung cancer cell lines; virus growth was highest in CLAC cells compared with the other cell lines and the induction of interferon (IFN)-beta and IFN-stimulated genes was at lower levels in CLAC cells. These results suggested that rMV-SLAMblind exhibits oncolytic effect against some canine lung cancer cells and the cellular response after the virus infection may influence its efficacy.

Dicalcin suppresses invasion and metastasis of mammalian ovarian cancer cells by regulating the ganglioside-Erk1/2 axis

Metastasis, a multistep process including cancer cell migration and invasion, is the major cause of mortality in patients with cancer. Here, we investigated the effect of dicalcin, a Ca2+-binding protein, on the invasion and metastasis of ovarian cancer (OC) cells. Extracellularly administered dicalcin bound to the membrane of OV2944 cells, mouse OC cells, and suppressed their migration in vitro; however, cell viability or proliferation were unaffected. Repeated intraperitoneal injection of a partial peptide of dicalcin (P6) prolonged the survival, and reduced the number of microcolonies in the livers of cancer-bearing mice. P6 bound to the ganglioside GM1b in a solid-phase assay; treatment with P6 inhibited the constitutive activation of Erk1/2 in OC cells, whereas excess administration of GM1b augmented Erk activity and cancer cell migration in vitro. Thus, dicalcin, a novel suppressor of invasion and metastasis of OC cells, acts via the GM1b-Erk1/2 axis to regulate their migration.

Antioxidant, Antiproliferative, Pro-apoptotic and cell cycle arrest properties of crude extract and biofractions of Hybanthus enneaspermus Linn. to combat breast cancer

Objective: According to the World Health Organisation, breast cancer is presently the most common cancer diagnosed in women globally. Polyphenolic compounds act as antioxidants, improve health, and reduce risk and proliferation of various types of cancers. Hybanthus enneaspermus Linn. is a beneficial medicinal plant, reported to possess antimicrobial, antioxidant, anti-inflammatory, neuroprotective, cardioprotective, and nephroprotective properties etc. Methods: The current study involved the evaluation the antioxidant, antiproliferative, apoptotic and cell cycle arrest potential of the ethanolic leaf extract of Hybathus enneaspermus Linn. (EEHE), its toluene soluble, toluene insoluble, ethyl acetate and methanol soluble biofractions viz. TFHE, ITHE, EFHE, and MFHE to combat breast cancer. In vitro antioxidant activities were evaluated using DPPH, Hydrogen peroxide, Nitric oxide and ABTS free radical scavenging assays. In vitro antiproliferative activity against MCF-7 cells was assayed using the Sulforhodamine method, while apoptosis and cell cycle assays were analysed by flow cytometry. Results: MFHE exhibited significant in vitro antioxidant activity with IC50 values of 21.10±0.39 μg/mL and 25.99±4.66μg/mL, when compared against standard ascorbic acid with IC50 values of 11.19±1.09 μg/mL and 9.30±0.26μg/mL in DPPH and nitric oxide assays respectively. EFHE displayed substantial antioxidant potential in ABTS and hydrogen peroxide assays with IC50 values of 40.38±0.88μg/mL and 99.11± 13.59μg/mL, while ITHE showed considerable activity with IC50 < 100μg/mL in DPPH, nitric oxide and ABTS assays. TFHE demonstrated significant antiproliferative activity by sulforhodamine assay, with GI50 value of 10.22 6.72µg/mL, while EEHE and ITHE showed substantial activity with GI50 values of 41.42±3.74µg/mL and 64.37±7.07µg/mL respectively, as against the standard drug Adriamycin (GI50 < 10µg/mL) used. In the apoptosis assay, ITHE showed 11.31±0.82% cells in late apoptosis and 34.48±1.57 % cells in necrosis as compared to standard Adriamycin indicated 13.67±1.02 % cells in late apoptosis and 8.58±0.65 % cells in necrosis. In cell cycle analysis, ITHE displayed significant apoptotic activity with 20.15±1.37 % cells in SubG1 phase and 13.99±1.65 % cells arrested in G2-M phase as compared to the control. Conclusion: The study thus revealed that MFHE, EFHE and ITHE biofractions showed significant antioxidant activities, while EEHE, TFHE and ITHE exhibited substantial antiproliferative activity against mammary cancer cells. Additionally, ITHE induced remarkable apoptotic activity and cell cycle arrest in the MCF-7 cells. The therapeutic benefits may be credited to the bioactive constituents present in the ITHE fraction viz. polyphenolics, flavonoids etc.; however, the molecular mechanisms may need to be evaluated further.

Cystine/glutamate antiporter xCT deficiency reduces metastasis without impairing immune system function in breast cancer mouse models

BackgroundThe upregulation of antioxidant mechanisms is a common occurrence in cancer cells, as they strive to maintain balanced redox state and prevent oxidative damage. This includes the upregulation of the cystine/glutamate antiporter xCT, which plays a crucial role in protecting cancer cells from oxidative stress. Consequently, targeting xCT has become an attractive strategy for cancer treatment. However, xCT is also expressed by several types of immune cells where it has a role in proliferation and effector functions. In light of these observations, a comprehensive understanding of the specific role of xCT in the initiation and progression of cancer, as well as its potential impact on the immune system within the tumor microenvironment and the anti-tumor response, require further investigation.MethodsWe generated xCTnull BALB/c mice to investigate the role of xCT in the immune system and xCTnull/Erbb2-transgenic BALB-neuT mice to study the role of xCT in a mammary cancer-prone model. We also used mammary cancer cells derived from BALB-neuT/xCTnull mice and xCTKO 4T1 cells to test the contribution of xCT to malignant properties in vitro and in vivo.ResultsxCT depletion in BALB-neuT/xCTnull mice does not alter autochthonous tumor initiation, but tumor cells isolated from these mice display proliferation and redox balance defects in vitro. Although xCT disruption sensitizes 4T1 cells to oxidative stress, it does not prevent transplantable tumor growth, but reduces cell migration in vitro and lung metastasis in vivo. This is accompanied by an altered immune cell recruitment in the pre-metastatic niche. Finally, systemic depletion of xCT in host mice does not affect transplantable tumor growth and metastasis nor impair the proper mounting of both humoral and cellular immune responses in vivo.ConclusionsxCT is dispensable for proper immune system function, thus supporting the safety of xCT targeting in oncology. Nevertheless, xCT is involved in several processes required for the metastatic seeding of mammary cancer cells, thus broadening the scope of xCT-targeting approaches.

Inhibition of Dipeptidyl Peptidase-4 Activates Autophagy to Promote Survival of Breast Cancer Cells via the mTOR/HIF-1α Pathway.

Autophagy plays a complex role in breast cancer cell survival, metastasis, and chemotherapeutic resistance. Dipeptidyl peptidase (DPP)-4, a therapeutic target for type 2 diabetes mellitus, is also involved in autophagic flux. The potential influence of DPP-4 suppression on cancer biology remains unknown. Here, we report that DPP-4 deficiency promotes breast cancer cell survival via the induction of autophagy by the C-X-C motif chemokine 12 (CXCL12)/C-X-C receptor 4 (CXCR4)/mammalian target of rapamycin (mTOR)/hypoxia inducible factor (HIF)-1α axis. DPP-4 knockdown and DPP-4 inhibitor KR62436 (KR) treatment both increased the levels of LC3II and HIF-1α in cultured human breast and mouse mammary cancer cells. The KR-induced autophagic phenotype in cancer cells was inhibited by treatment with the CXCR4 inhibitor AMD3100 and rapamycin. HIF-1α knockdown also suppressed breast cancer autophagy induced by KR. The autophagy inhibitor 3-methyladenine significantly blocked the KR-mediated suppression of cleaved caspase-3 levels and apoptosis in breast cancer cell lines. Finally, we found that the metformin-induced apoptosis of DPP-4-deficient 4T1 mammary cancer cells was associated with the suppression of autophagy. Our findings identify a novel role for DPP-4 inhibition in the promotion of breast cancer survival by inducing CXCL12/CXCR4/mTOR/HIF-1α axis-dependent autophagy. Metformin is a potential drug that counteracts the breast cancer cell survival system.

Hg(II)/Fe(III) Turn‐On Fluorescence Response of Rhodamine‐Anthracene Derivatives with Variable Diamine Chain Length

AbstractTwo rhodamine‐anthracene derivative probes (RA1 and RA2) were designed and synthesized to incorporate different lengths of diamine chains between the rhodamine and anthracene moieties. Among the 16 different metal ions tested, RA1 exhibited the highest fluorescence enhancement in response to Hg2+ with a limit of detection (LOD) of 3.76×10−7 M, while RA2 showed the greatest fluorescence enhancement in the presence of Fe3+ with the LOD of 2.41×10−7 M. Notably, RA1 effectively eliminated the interference caused by Fe3+ during Hg2+ detection, whereas RA2 successfully eliminated the interference of Hg2+ during Fe3+ determination. This response difference between the two ions holds particular importance in scenarios where both heavy metal ions coexist. Additionally, fluorescence microscopy imaging of mouse mammary cancer cells (4T1) under the influence of Fe3+ demonstrated the potential applications of the probe. This study highlights the significance of a simple molecular design approach in tailoring probe selectivity by modifying the intramolecular flexible chain length.

Investigating malignancy-dependent mechanical properties of breast cancer cells.

Cancer invasiveness significantly impacts cellular mechanical properties which regulate cell motility and, subsequently, cell metastatic potential. Understanding the adhesion forces and stiffness/rigidity of cancer cells can provide better insights into their mechanical adaptability related to their degree of invasiveness. Here, we used single-cell force spectroscopy in conjunction with quartz crystal microbalance-with dissipation measurements to compare the mechanical properties of mammary epithelial cancer cells with different metastatic potentials, namely MCF-7 (non-invasive) and MDA-MB-231 (aggressive and highly invasive). Our results showed that MCF-7 exhibits larger adhesion forces, stronger intercellular forces, and a considerably stiff/rigid phenotype, contrary to MDA-MB-231. The biomechanical properties obtained are associated with the malignant potential of these cells such that the forces of adhesion and viscoelasticity are inversely proportional to cell invasiveness. This study integrates a new quantitative tool with real-time measurements to provide better insights into the mechanics of cancer cells across metastatic stages.

Unprecedented Antimicrobial and Cytotoxic Polyketides from Cultures of Diaporthe africana sp. nov.

Four unprecedented polyketides named isoprenylisobenzofuran B (2), isoprenylisobenzofuran C1/C2 (3), diaporisoindole F1/F2 (4), and isochromophilonol A1/A2 (7) were isolated from ethyl acetate extracts of the newly described endophytic fungus Diaporthe africana. Additionally, the previously reported cyclic depsipeptide eucalactam B (1) was also identified, along with the known compounds diaporisoindole A/B (5), tenellone B (6) and beauvericin (8). The taxonomic identification of the fungus was accomplished using a polyphasic approach combining multi-gene phylogenetic analysis and microscopic morphological characters. The structures 1-8 were determined by a detailed analysis of their spectral data, namely high-resolution electrospray ionization mass spectrometry (HR-ESIMS), 1D/2D nuclear magnetic resonance (NMR) spectroscopy, as well as electronic circular dichroism (ECD) spectra. In addition, chemical methods such as Marfey's analysis were also employed to determine the stereochemistry in compound 1. All the compounds obtained were evaluated for antimicrobial and in vitro cytotoxic properties. Compounds 3-8 were active against certain fungi and Gram-positive bacteria with MIC values of 8.3 to 66.6 µg/mL. In addition, 3-5 displayed cytotoxic effects (22.0 ≤ IC50 ≤ 59.2 µM) against KB3.1 and L929 cell lines, whereas compounds 6-8 inhibited the growth of seven mammalian cancer cell lines with IC50 ranging from 17.7 to 49.5 µM (6), 0.9 to 12.9 µM (7) and 1.9 to 4.3 µM (8).

Cancer Cell Membrane Wrapped Nanoparticles for the Delivery of a Bcl-2 Inhibitor to Triple-Negative Breast Cancer.

Overexpression of the antiapoptotic protein B-cell lymphoma 2 (Bcl-2) is correlated with poor survival outcomes in triple-negative breast cancer (TNBC), making Bcl-2 inhibition a promising strategy to treat this aggressive disease. Unfortunately, Bcl-2 inhibitors developed to date have limited clinical success against solid tumors, owing to poor bioavailability, insufficient tumor delivery, and off-target toxicity. To circumvent these problems, we loaded the Bcl-2 inhibitor ABT-737 in poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) that were wrapped with phospholipid membranes derived from 4T1 murine mammary cancer cells, which mimic the growth and metastasis of human TNBC. We show that the biomimetic cancer cell membrane coating enabled the NPs to preferentially target 4T1 TNBC cells over noncancerous mammary epithelial cells in vitro and significantly increased NP accumulation in orthotopic 4T1 tumors in mice after intravenous injection by over 2-fold compared to poly(ethylene glycol)-poly(lactide-co-glycolic) (PEG-PLGA) copolymer NPs. Congruently, the ABT-737 loaded, cancer cell membrane-wrapped PLGA NPs (ABT CCNPs) induced higher levels of apoptosis in TNBC cells in vitro than ABT-737 delivered freely or in PEG-PLGA NPs. When tested in a syngeneic spontaneous metastasis model, the ABT CCNPs significantly increased apoptosis (evidenced by elevated active caspase-3 and decreased Bcl-2 staining) and decreased proliferation (denoted by reduced Ki67 staining) throughout tumors compared with saline or ABT-loaded PEG-PLGA NP controls. Moreover, the ABT CCNPs did not alter animal weight or blood composition, suggesting that the specificity afforded by the TNBC cell membrane coating mitigated the off-target adverse effects typically associated with ABT-737. Despite these promising results, the low dose of ABT CCNPs administered only modestly reduced primary tumor growth and metastatic nodule formation in the lungs relative to controls. We posit that increasing the dose of ABT CCNPs, altering the treatment schedule, or encapsulating a more potent Bcl-2 inhibitor may yield more robust effects on tumor growth and metastasis. With further development, drug-loaded biomimetic NPs may safely treat solid tumors such as TNBC that are characterized by Bcl-2 overexpression.

The Carnitine Palmitoyltransferase 1A Inhibitor Teglicar Shows Promising Antitumour Activity against Canine Mammary Cancer Cells by Inducing Apoptosis.

Canine mammary tumours (CMTs) are the most common cancer in intact female dogs. In addition to surgery, additional targeted and non-targeted therapies may offer survival benefits to these patients. Therefore, exploring new treatments for CMT is a promising area in veterinary oncology. CMT cells have an altered lipid metabolism and use the oxidation of fatty acids for their energy needs. Here we investigated the tumoricidal effects of teglicar, a reversible inhibitor of carnitine palmitoyl transferase 1A (CPT1A), the rate-limiting enzyme for fatty acid import into mitochondria, on two CMT cells, P114 and CMT-U229. Viability and apoptosis were examined in CMT cells using the crystal violet assay, trypan blue assay, and flow cytometry analysis. The expression of mediators of apoptosis signalling (e.g., caspase-9, caspase-8, and caspase-3) was assessed by quantitative real-time polymerase chain reaction and western blot analyses. Teglicar was able to decrease cell viability and induce apoptosis in P114 and CMT-U229 cells. At the molecular level, the effect of teglicar was associated with an upregulation of the mRNA expression levels of caspase-9, caspase-8, and caspase-3 and an increase in their protein levels. In summary, our results show that teglicar has a potential effect against CMTs through the induction of apoptotic cell death, making it a promising therapeutic agent against CMTs.