Breast Tumor Cells Research Articles

Cell cycle plasticity underlies fractional resistance to palbociclib in ER+/HER2− breast tumor cells

The CDK4/6 inhibitor palbociclib blocks cell cycle progression in Estrogen receptor-positive, human epidermal growth factor 2 receptor-negative (ER+/HER2-) breast tumor cells. Despite the drug's success in improving patient outcomes, a small percentage of tumor cells continues to divide in the presence of palbociclib-a phenomenon we refer to as fractional resistance. It is critical to understand the cellular mechanisms underlying fractional resistance because the precise percentage of resistant cells in patient tissue is a strong predictor of clinical outcomes. Here, we hypothesize that fractional resistance arises from cell-to-cell differences in core cell cycle regulators that allow a subset of cells to escape CDK4/6 inhibitor therapy. We used multiplex, single-cell imaging to identify fractionally resistant cells in both cultured and primary breast tumor samples resected from patients. Resistant cells showed premature accumulation of multiple G1 regulators including E2F1, retinoblastoma protein, and CDK2, as well as enhanced sensitivity to pharmacological inhibition of CDK2 activity. Using trajectory inference approaches, we show how plasticity among cell cycle regulators gives rise to alternate cell cycle "paths" that allow individual tumor cells to escape palbociclib treatment. Understanding drivers of cell cycle plasticity, and how to eliminate resistant cell cycle paths, could lead to improved cancer therapies targeting fractionally resistant cells to improve patient outcomes.

Metabolic Responses of Lung Adenocarcinoma Cells to Survive under Stressful Conditions Associated with Tumor Microenvironment.

Solid tumors frequently present a heterogeneous tumor microenvironment. Because tumors have the potential to proliferate quickly, the consequence is a reduction in the nutrients, a reduction in the pH (<6.8), and a hypoxic environment. Although it is often assumed that tumor clones show a similar growth rate with little variations in nutrient consumption, the present study shows how growth-specific rate (µ), the specific rates of glucose, lactate, and glutamine consumption (qS), and the specific rates of lactate and glutamate production (qP) of 2D-cultured lung tumor cells are affected by changes in their environment. We determined in lung tumor cells (A427, A549, Calu-1, and SKMES-1) the above mentioned kinetic parameters during the exponential phase under different culture conditions, varying the predominant carbon source, pH, and oxygen tension. MCF-7 cells, a breast tumor cell line that can consume lactate, and non-transformed fibroblast cells (MRC-5) were included as controls. We also analyzed how cell-cycle progression and the amino acid transporter CD98 expression were affected. Our results show that: (1) In glucose presence, μ increased, but qS Glucose and qP Lactate decreased when tumor cells were cultured under acidosis as opposed to neutral conditions; (2) most lung cancer cell lines consumed lactate under normoxia or hypoxia; (3) although qS Glutamine diminished under hypoxia or acidosis, it slightly increased in lactate presence, a finding that was associated with CD98 upregulation; and (4) under acidosis, G0/G1 arrest was induced in A427 cancer cells, although this phenomenon was significantly increased when glucose was changed by lactate as the predominant carbon-source. Hence, our results provide an understanding of metabolic responses that tumor cells develop to survive under stressful conditions, providing clues for developing promising opportunities to improve traditional cancer therapies.

Abstract A044: P2Y2 signaling disruption reduces ATP-dependent calcium elevation and actin localization to promote breast tumor cell dissemination

Abstract The tumor microenvironment and wound healing after injury both contain extremely high concentrations of the extracellular signaling molecule, adenosine triphosphate (ATP) compared to normal tissue. P2Y2 receptor, an ATP-activated purinergic receptor, is typically associated with pulmonary, endothelial, and neural cell signaling. Here we report the importance of ATP-dependent P2Y2 signaling in breast epithelial cells and how it is altered in metastatic breast cancer. In response to ATP activation, P2Y2 receptor signaling causes an increase of intracellular calcium (Ca2+) in non-tumorigenic breast epithelial cells, while their tumorigenic and metastatic counterparts have significantly reduced Ca2+ responses. The non-tumorigenic cells respond to increased Ca2+ with actin polymerization and localization to cell edges, while the metastatic cells remained unaffected. The increase in intracellular Ca2+ after ATP stimulation was blunted using a P2Y2 antagonist, which also prevented actin mobilization and caused cell dissemination from spheroids in non-tumorigenic breast epithelial cells. Furthermore, the lack of Ca2+ concentration changes and actin mobilization in the metastatic breast cancer cells could be due to reduced P2Y2 expression, which correlates with poorer overall survival in breast cancer patients. This study elucidates rapid changes that occur after elevated intracellular Ca2+ in breast epithelial cells and how metastatic cancer cells have adapted to evade this cellular response. Citation Format: Makenzy Mull, Stephen Pratt, Keyata Thompson, David Annis, Julia Ju, Megan Stemberger, Liron Boyman, Michele Vitolo, W. Jonathan Lederer, Stuart Martin. P2Y2 signaling disruption reduces ATP-dependent calcium elevation and actin localization to promote breast tumor cell dissemination [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr A044.

Abstract B046: Exploring the potential of commensal polyomavirus as a promising approach for breast cancer treatment

Abstract Cancer is a leading cause of mortality worldwide, accounting for nearly one in six deaths. Our understanding of the immune system role in cancer control has increased dramatically in recent decades, facilitating the recent development of effective cancer immunotherapies, which have significantly improved the survival of cancer patients. However, current immunotherapies can induce overactive immune responses with severe even fatal outcomes. Moreover, immunotherapy may not work in every scenario, especially in ‘cold’ tumors that lack immune cell infiltration. Thus, more effective immunotherapies with fewer side effects are under active investigation. Viruses are one of the most abundant biological entities in the world; about 12% to 20% of human cancers are associated with viral infections. Viral antigens can increase tumor immunogenicity, triggering T cell immunity against tumor cells. Polyomaviruses are small, nonenveloped double-stranded DNA viruses that are widespread. In immunocompetent hosts, polyomaviruses remain at a low persistent level in the host after the primary infection, which appears to cause little or no symptoms. Previous studies have shown high polyomavirus seroprevalence and the frequent presence of polyomavirus-specific T cells in healthy adult blood donors. In the elderly population, Merkel cell polyomavirus (MCPyV) infection is linked to Merkel cell carcinoma (MCC), a rare, aggressive skin cancer associated with immunosuppression. MCPyV integration into the genome is the primary oncogenic event in ~80% of MCC cases, and the remaining virus-negative MCC cases are associated with ultraviolet (UV) radiation. MCPyV-induced MCCs are associated with more intratumor immune cells and better responses to cancer therapy. Moreover, BK and JC polyomavirus positive lymphoma patients showed a trend toward significantly better overall survival. These clinical data suggest that polyomavirus in tumors may increase tumor immunogenicity. Thus, polyomavirus presents an intriguing opportunity to develop a novel strategy to enhance cancer immunogenicity. We utilized mouse polyomavirus (MPyV) to colonize typically ‘cold’ breast tumor cell line E0771 breast cancer cells in mice. MPyV infection blocked the growth of tumors in immunocompetent mice and promoted immune cell infiltration when intratumorally delivered to the tumor. The tumor rejection activity of polyomavirus is depend on CD4 and CD8 T cells. Unlike conventional oncolytic viruses which directly lyse the infected cells and trigger a nonspecific inflammatory response, polyomavirus does not lyse the colonized cells, and it induces a relatively low level of inflammation. Instead, polyomavirus stimulates viral antigen expression in tumors that boosts T cell response leading to epitope spreading to tumor-associated antigens. The outcomes of this research will establish the utility of commensal polyomavirus as a novel agent for cancer immunotherapy. Citation Format: YUN XIA. Exploring the potential of commensal polyomavirus as a promising approach for breast cancer treatment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr B046.

Secretomics reveals hormone-therapy of breast cancer may induce survival by facilitating hypercoagulation and immunomodulation in vitro

Tumour cell haematogenous dissemination is predicated on molecular changes that enhance their capacity for invasion and preparation of the pre-metastatic niche. It is increasingly evident that platelets play an essential role in this transformation. The systemic nature of signalling molecules and extravascular factors that participate in mediating platelet-tumour cell interactions led to the development of an in vitro co-culture using whole blood and breast tumour cells, allowing us to decipher the impact of hormone-therapy on tumour cells and associated changes in the plasma proteome. Using mass spectrometry, we determined dysregulation of proteins associated with maintaining an invasive tumour phenotype. Tumour changes in genes associated with EMT and survival were documented. This is postulated to be induced via tumour cell interactions with the coagulatory and immune systems. Results highlight tumour cell adaptability to both treatment and blood resulting in a pro-tumorigenic response and a hypercoagulatory state. We illustrate that the breast cancer cell secretome can be altered by hormone-therapy, subject to the tumour subphenotype and linked to platelet activation. More sophisticated co-culture systems are required to recapitulate these interactions to better understand tumorigenesis. Moreover, deeper plasma profiling, using abundant protein depleted and/or vesicle enriched strategies, will likely reveal additional secretory proteins related to tumour cell-platelet interactions.

CYP1-Activation and Anticancer Properties of Synthetic Methoxylated Resveratrol Analogues.

Naturally occurring stilbenoids, such as the (E)-stilbenoid resveratrol and the (Z)-stilbenoid combretastatin A4, have been considered as promising lead compounds for the development of anticancer drugs. The antitumour properties of stilbenoids are known to be modulated by cytochrome P450 enzymes CYP1A1 and CYP1B1, which contribute to extrahepatic phase I xenobiotic and drug metabolism. Thirty-four methyl ether analogues of resveratrol were synthesised, and their anticancer properties were assessed, using the MTT cell proliferation assay on a panel of human breast cell lines. Breast tumour cell lines that express CYP1 were significantly more strongly affected by the resveratrol analogues than the cell lines that did not have CYP1 activity. Metabolism studies using isolated CYP1 enzymes provided further evidence that (E)-stilbenoids can be substrates for these enzymes. Structures of metabolic products were confirmed by comparison with synthetic standards and LC-MS co-elution studies. The most promising stilbenoid was (E)-4,3',4',5'-tetramethoxystilbene (DMU212). The compound itself showed low to moderate cytotoxicity, but upon CYP1-catalysed dealkylation, some highly cytotoxic metabolites were formed. Thus, DMU212 selectively affects proliferation of cells that express CYP1 enzymes.

ZO-1 regulates the migration of mesenchymal stem cells in cooperation with α-catenin in response to breast tumor cells

sMesenchymal stem cells are recruited from the bone marrow into breast tumors, contributing to the creation of a tumor microenvironment that fosters tropism for breast tumors. However, the intrinsic mechanisms underlying the recruitment of bone marrow-derived mesenchymal stem cells (MSCs) into the breast tumor microenvironment are still under investigation. Our discoveries identified zonula occludens-1 (ZO-1) as a specific intrinsic molecule that plays a vital role in mediating the collective migration of MSCs towards breast tumor cells and transforming growth factor beta (TGF-β), which is a crucial factor secreted by breast tumor cells. Upon migration in response to MDA-MB-231 cells and TGF-β, MSCs showed increased formation of adherens junction-like structures (AJs) expressing N-cadherin and α-catenin at their cell-cell contacts. ZO-1 was found to be recruited into the AJs at the cell-cell contacts between MSCs. Additionally, ZO-1 collaborated with α-catenin to regulate AJ formation, dependently on the SH3 and GUK domains of the ZO-1 protein. ZO-1 knockdown led to the impaired migration of MSCs in response to the stimuli and subsequent downregulation of AJs formation at the cell-cell contacts during MSCs migration. Overall, our study highlights the novel role of ZO-1 in guiding MSC migration towards breast tumor cells, suggesting its potential as a new strategy for controlling and re-engineering the breast tumor microenvironment.

Assessment of IL-9/IL-9R Expression and Therapeutic Effect of IL-9 Blockade in a Mouse Breast Cancer Model

Background and Hypothesis:IL-9 is a cytokine produced by TH9, mast cells, and innate lymphoid cells. IL-9 acts on the IL-9 receptor (IL-9R) and is primarily involved in parasitic immunity and allergic inflammation. IL-9 has anti-tumor effects in solid tumors such as melanoma. IL-9 also has pro-tumor effects in various cancer types, including lung cancer. Previous studies have shown that increased serum IL-9 in breast cancer patients correlates with tumor metastasis. Therefore, we hypothesize that IL9 signaling contributes to breast tumor metastasis and blocking IL-9 may have a therapeutic benefit in reducing metastasis.&#x0D; Methods:Mice were orthotopically implanted with 4T1 breast tumor cells. Organs were harvested after 28 days. Total RNA was extracted and expression of IL-9/IL-9R and leukocyte markers were assessed. To test therapeutic effect of IL-9 blockade, tumor-bearing mice were treated with anti-IL-9 monoclonal antibody (αIL-9). Tumor sizes were monitored every 4 days. On day 28, tumor tissue was harvested and weighed. Lung was also harvested and stained with H&amp;E for metastasis analysis.&#x0D; Results:Primary tumor growth was not altered by αIL-9. The effect of αIL-9 treatment on lung metastasis is pending pathological analysis. We further examined IL-9R to define how tumor burden alters expression of IL-9 and IL-9R across tissues. Lymphoid organs, such as the thymus, spleen, and inguinal lymph node (inguinal LN), exhibit high levels of IL-9R. Additionally, the small intestine is notably enriched with IL-9R. The thymus exhibited the highest IL-9 expression.&#x0D; Conclusion and Future Directions:Although blockade of IL-9 did not impact tumor growth in this model, this will be examined in other models to confirm the findings. Further research is needed to investigate the potential therapeutic benefits of αIL-9 with other established therapies. We observed that there is altered IL-9 and IL-9R expression in tumor bearing mice and the physiological significance of that finding remains to be determined.

Aptamer-Based Recognition of Breast Tumor Cells: A New Era for Breast Cancer Diagnosis.

Breast cancer is one of the leading causes of death among women worldwide and can be classified into four major distinct molecular subtypes based on the expression of specific receptors. Despite significant advances, the lack of biomarkers for detailed diagnosis and prognosis remains a major challenge in the field of oncology. This study aimed to identify short single-stranded oligonucleotides known as aptamers to improve breast cancer diagnosis. The Cell-SELEX technique was used to select aptamers specific to the MDA-MB-231 tumor cell line. After selection, five aptamers demonstrated specific recognition for tumor breast cell lines and no binding to non-tumor breast cells. Validation of aptamer specificity revealed recognition of primary and metastatic tumors of all subtypes. In particular, AptaB4 and AptaB5 showed greater recognition of primary tumors and metastatic tissue, respectively. Finally, a computational biology approach was used to identify potential aptamer targets, which indicated that CSKP could interact with AptaB4. These results suggest that aptamers are promising in breast cancer diagnosis and treatment due to their specificity and selectivity.

Orbygnia martiana: Immunomodulation, oxidative stress and induction of apoptosis in breast tumor cells

Studies have demonstrated the ability of Orbygnia martiana to alter apoptosis and necrosis in tumor cells, but the results are still controversial. Thus, this study aimed to evaluate the effects of Orbygnia martiana under the mechanisms of oxidative stress in coculture between human peripheral blood mononuclear cells and breast tumor cells and its association with cell death mechanisms.

METTL18 functions as a Phenotypic Regulator in Src-Dependent Oncogenic Responses of HER2-Negative Breast Cancer.

Methyltransferase-like (METTL)18 has histidine methyltransferase activity on the RPL3 protein and is involved in ribosome biosynthesis and translation elongations. Several studies have reported that actin polymerization serves as a Src regulator, and HSP90 is involved in forming polymerized actin bundles. To understand the role of METTL18 in breast cancer and to demonstrate the importance of METTL18 in HER-2 negative breast cancer metastasis, we used biochemical, molecular biological, and immunological approaches in vitro (breast tumor cell lines), in vivo (tumor xenograft model), and in samples of human breast tumors. A gene expression comparison of 31 METTL series genes and 22 methyltransferases in breast cancer patients revealed that METTL18 is highly amplified in human HER2-negative breast cancer. In addition, elevated levels of METTL18 expression in patients with HER2-negative breast cancer are associated with poor prognosis. Loss of METTL18 significantly reduced the metastatic responses of breast tumor cells in vitro and in vivo. Mechanistically, METTL18 indirectly regulates the phosphorylation of the proto-oncogene tyrosine-protein kinase Src and its downstream molecules in MDA-MB-231 cells via METTL18-mediated RPL3 methylation, which is also involved in determining HSP90 integrity and protein levels. In confocal microscopy and F/G-actin assays, METTL18 was found to induce actin polymerization via HSP90. Molecular events involving METTL18, RPL3, HSP90, and actin polymerization yielded Src phosphorylated at both tyrosine 419 and tyrosine 530 with kinase activity and oncogenic functions. Therefore, it is suggested that the METTL18-HSP90-Actin-Src regulatory axis plays critical oncogenic roles in the metastatic responses of HER2-negative breast cancer and could be a promising therapeutic target.

Elemental biomapping of human tissues suggests toxic metals such as mercury play a role in the pathogenesis of cancer.

Toxic metals such as mercury, lead, and cadmium have multiple carcinogenic capacities, including the ability to damage DNA and incite inflammation. Environmental toxic metals have long been suspected to play a role in the pathogenesis of cancer, but convincing evidence from epidemiological studies that toxic metals are risk factors for common neoplasms has been difficult to gain. Another approach is to map the location of potentially toxic elements in normal human cells where common cancers originate, as well as in the cancers themselves. In this Perspective, studies are summarized that have used elemental biomapping to detect toxic metals such as mercury in human cells. Two elemental biomapping techniques, autometallography and laser ablation-inductively coupled-mass spectrometry imaging, have shown that multiple toxic metals exist in normal human cells that are particularly prone to developing cancer, and are also seen in neoplastic cells of breast and pancreatic tumors. Biomapping studies of animals exposed to toxic metals show that these animals take up toxic metals in the same cells as humans. The finding of toxic metals such as mercury in human cells prone to cancer could explain the increasing global incidence of many cancers since toxic metals continue to accumulate in the environment. The role of toxic metals in cancer remains to be confirmed experimentally, but to decrease cancer risk a precautionary approach would be to reduce emissions of mercury and other toxic metals into the environment from industrial and mining activities and from the burning of fossil fuels.

Benzo[a]pyrene exposure prevents high fat diet-induced obesity in the 4T1 model of mammary carcinoma.

Tumor metastasis is the main cause of death in triple-negative breast cancer (TNBC) patients. TNBC is the most aggressive subtype of breast cancer lacking the expression of estrogen, progesterone, and human epidermal growth factor 2 receptors, thereby rendering it insensitive to targeted therapies. It has been well-established that excess adiposity contributes to the progression of TNBC; however, due to the aggressive nature of this breast cancer subtype, it is imperative to determine how multiple factors can contribute to progression. Therefore, we aimed to investigate if exposure to an environmental carcinogen could impact a pre-existing obesity-promoted cancer. We utilized a spontaneous lung metastatic mouse model where 4T1 breast tumor cells are injected into the mammary gland of BALB/c mice. Feeding a high fat diet (HFD) in this model has been shown to promote tumor growth and metastasis. Herein, we tested the effects of both a HFD and benzo(a)pyrene (B[a]P) exposure. Our results indicate that diet and B[a]P had no tumor promotional interaction. However, unexpectedly, our findings reveal an inhibitory effect of B[a]P on body weight, adipose tissue deposition, and tumor volume at time of sacrifice specifically under HFD conditions.

Quantitative determination and subcellular mapping of Pt-based drugs in single breast tumour cells via laser ablation-ICP-mass spectrometry

This study utilizes LA-ICP-MS to reveal the distribution and determine the concentration of Pt in MDA-MB-231 cells, providing insight into the mechanism and efficacy of Pt-based chemotherapeutic drugs.

Heterogeneous Response of Tumor Cell Lines to Inhibition of Aspartate β-hydroxylase.

Background: Cancer development involves alterations in key cellular pathways, with aspartate β-hydroxylase (ASPH) emerging as an important player in tumorigenesis. ASPH is upregulated in various cancer types, where it promotes cancer progression mainly by regulating the Notch1 and SRC pathways. Methods: This study explored the responses of various human cervical, pharyngeal, and breast tumor cell lines to second- and third-generation ASPH inhibitors (MO-I-1151 and MO-I-1182) using proliferation, migration, and invasion assays; western blotting; and cell cycle analysis. Results: ASPH inhibition significantly reduced cell proliferation, migration, and invasion and disrupted both the canonical and noncanonical Notch1 pathways. The noncanonical pathway was particularly mediated by AKT signaling. Cell cycle analysis revealed a marked reduction in cyclin D1 expression, further confirming the inhibitory effect of ASPH inhibitors on cell proliferation. Additional analysis revealed G0/G1 arrest and restricted progression into S phase, highlighting the regulatory impact of ASPH inhibitors on the cell cycle. Furthermore, ASPH inhibition induced distinctive alterations in nuclear morphology. The high heterogeneity in the responses of individual tumor cell lines to ASPH inhibitors, both quantitatively and qualitatively, underscores the complex network of mechanisms that are regulated by ASPH and influence the efficacy of ASPH inhibition. The effects of ASPH inhibitors on Notch1 pathway activity, cyclin D1 expression, and nuclear morphology contribute to the understanding of the multifaceted effects of these inhibitors on cancer cell behavior. Conclusion: This study not only suggests that ASPH inhibitors are effective against tumor cell progression, in part through the induction of cell cycle arrest, but also highlights the diverse and heterogeneous effects of these inhibitors on the behavior of tumor cells of different origins.

Crosstalk between breast cancer-derived microRNAs and brain microenvironmental cells in breast cancer brain metastasis.

Breast cancer is the most frequent malignancy in women, constituting 15.2% of all new cancers diagnosed in the United States. Distant breast cancer metastasis accounts for the majority of breast cancer-related deaths; brain metastasis is the third most common site for metastatic breast cancer but is associated with worst prognosis of approximately eight months of survival. Current treatment options for breast cancer brain metastasis (BCBM) are limited and ineffective. To help identify new and effective therapies for BCBM, it is important to investigate the mechanisms by which breast cancer cells metastasize to the brain and thrive in the brain microenvironment. To this end, studies have reported that primary breast tumor cells can prime brain microenvironmental cells, including, astrocytes and microglia, to promote the formation of BCBM through the release of extracellular vesicle-microRNAs (miRNAs). Breast tumor-derived miRNAs can also promote breast cancer cell invasion through the blood-brain barrier by disrupting the integrity of the brain microvascular endothelial cells. In this review, we summarize current literature on breast cancer-derived BCBM-promoting miRNAs, cover their roles in the complex steps of BCBM particularly their interactions with microenvironmental cells within the brain metastatic niche, and finally discuss their therapeutic applications in the management of BCBM.

Vitis vinifera Kyoho-derived exosome-like nanoparticles-based drug delivery and therapeutic modalities for breast cancer therapy

Fruit-derived exosomes have the capability to deliver drugs and target disease cells. In this primary, Vitis vinifera Kyoho-isolated exosome-like nanoparticles (VKENPs) were extracted and delivered with and without multiple drugs to investigate therapeutic modalities for drug delivery and in vitro breast tumor (BT) treatment. For this purpose, VKENPs were isolated through simple single-step centrifugation and 0.22 μm pore size filtration method and ultra-centrifugation at 100,000×g. Multiple drugs such as metformin, doxorubicin, and tamoxifen were loaded and delivered to the BT cells to assess cellular internalization time, viability, cytotoxicity, ROS generation, and apoptosis. The isolated VKENP's average size was 40 nm with a good polydispersity (113.1 ± 0.117 PDI Mw) and zeta potential (−23 mV), negligibly cytotoxic to healthy tissues (10 % cytotoxicity) along with rapid cellular internalization (within 6 h), and are biased towards tumors by killing 56 % 4T1 cells at 72 h. Moreover, VKEMDT induced 90 % cell death in BT cells via enhancing ROS generation level and inducing apoptosis and necrosis cell death channels. Therefore, the prepared VKENPs successfully induced cell death and have the potential to load multiple drugs with effective targeting of tumor cells. Thus, VKENPs may expand the scope of drug therapies while reducing the off-target effects.

MRI-Based Interstitial Fluid Velocity Analysis for Drug Delivery Efficiency Evaluation in Tumor.

There are many flow behaviors in solid tumors, including intravascular, bloodstream, and interstitial convection. Studies have shown that tumor interstitial fluid (TIF) is an important part of tumor microenvironment regulation and affects drug delivery and metabolism between tumor cells. Magnetic resonance imaging (MRI) is suitable for detecting the flow rates of liquids in tissues. Clinical phase contrast PC-MRI technology has been designed to observe the blood flow in large vessels such as arteries and veins; however, it is not sensitive enough to deal with slow flow velocity. Our previously developed vertical plane echo PC-MRI technology, the Velocity Mapping sequence, improved the signal-to-noise ratio (SNR) for measuring slow interstitial fluid rate. In this study, this sequence was used to determine the TIF flow rate in MDA-MB-231 human breast tumor cells used in BALB/c nude male mice. Two different sizes of contrast agents were intravenously injected, and the relationship between their distribution and the TIF flow rate was studied for the first time. Combining the results of clinical scanning showed that small-molecule DTPA-Gd (diethylenetriaminepentaacetic acid-gadolinium) was distributed immediately around the tumor margin after the injection. This distribution was positively correlated to the high flow rate area of the TIF before administration. In contrast, nanoparticles NaGdF4-PEG (polyethylene glycol) entered the tumor and reached their peak at 3 h. Drug distribution was negatively correlated with the high-flow-rate region of the TIF. Investigation of the TIF velocity can help better understand the fluid behavior in tumors and its role in drug delivery.

Evaluation of the Synergistic Effect of the Combination of Doxorubicin and Vorinostat on Breast Tumor Cells Using the Loewe Model

The combination of two or more medications is increasingly more common in the development of new treatment guidelines for common diseases. Thus, the use of combinations of histone deacetylase inhibitors with chemotherapeutic agents is a current trend in solid tumor treatment. The aim of this study was to investigate an effective vorinostat (SAHA) to doxorubicin (DOX) ratio for the treatment of different subtypes of breast cancer. The survival of HCC-1954, SKBR-3, MCF-7, MCF-7/ADR, MDA-MB-231 cell lines was assessed under incubation conditions with 64 variants of SAHA and DOX combinations using the MTT assay. This made it possible to determine the effect of interactions of SAHA/DOX combinations (antagonistic, additive, synergistic), as well as calculate the SAHA/DOX synergy index using the Loewe additivity model. The effect of SAHA/DOX ratios with the highest synergistic index for each tumor cell line was confirmed using the Chou-Talalay method. It was shown that the SAHA/DOX combination exhibited the greatest synergism in relation to HCC-1954, MCF-7/ADR and SKBR-3 cell lines belonging to the HER2-positive subtype. The average value of SAHA/DOX ratio with the highest synergy against breast cancer cells was 30:1 (SAHA to DOX, respectively). The ability of SAHA/DOX combination to effectively trigger apoptosis was confirmed in the most sensitive to SAHA/DOX therapy HCC-1954 cells. Thus, the Loewe model made it possible to identify the drug combination with the highest synergistic anticancer effect, which was confirmed using Chou-Talalay method. The data obtained demonstrates great potential of SAHA/DOX combination (30:1) for the treatment of HER2-positive breast cancer.

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.