Triple negative breast cancer (TNBC) is an aggressive variant of breast cancer that lacks the expression of estrogen, progesterone, and human epithelial growth factor receptors. Due to the scarce availability of receptor‐targeted or hormonal treatments, TNBC patients are submitted to taxane‐based chemotherapies like paclitaxel. Patients initially respond to paclitaxel, but 4 out of 10 patients may develop tumor recurrence along with high metastasis and mortality rates. Several studies demonstrate that paclitaxel may induce chemoresistance and metastasis through the activation of Toll‐Like Receptor 4 (TLR4)/NFKB signaling pathway, a known cancer prognostic marker in breast cancer. Hence, new treatments are needed to improve TNBC prognosis in patients. Recently, our laboratory and collaborators developed MBQ‐167, a potent Rac and Cdc42 inhibitor that decreases tumor burden, cell proliferation, and metastasis in TNBC mouse models. In preliminary studies with TNBC mice, we observed that MBQ‐167/Paclitaxel combination treatment prevented metastasis progression compared to paclitaxel treatment alone. This led us to hypothesize that MBQ‐167 chemosensitizes aggressive breast cancer cells and reduces metastasis by blocking Rac/Cdc4, hence decreasing their downstream target NfkB activity. This research project aims to evaluate cellular and molecular events that explain how MBQ‐167 prevents paclitaxel‐induced metastasis. Here, we generated TLR4‐knockdowns (TLR4‐KD) in MDA‐MB‐231 TNBC cell lines using lentiviral particles with shRNAs against the TLR4 mRNA. After knockdown validation with western blot analysis (WB), Wildtype (MDA‐MB‐231), Scramble control knockdowns (Sc‐KD), and TLR4‐KD cells were treated with different concentrations of MBQ‐167, paclitaxel, doxorubicin, or combinations. After treatments, we evaluated the effect on cell viability from MTT assays at 96 and 120 hours, cell apoptosis through Caspase‐Glo 3/7 Assays at 48 hours, and cellular migration through scratch wound healing assays. Our results demonstrate that partial inhibition of TLR4 decreases the cell viability of cells, increases apoptosis, and decreases cell migration after treatment with MBQ‐167 (250 nM and 500 nM), Paclitaxel (5 nM and 10 nM), or Doxorubicin (250 nM and 500 nM). We also observed an additive response upon combinatorial treatments with MBQ‐167/Paclitaxel and MBQ‐167/Doxorubicin when TLR4‐KD cells were compared to wild‐type and Sc‐KD cells. Altogether, these results suggest that TLR4‐KD chemosensitizes cells to Paclitaxel and Doxorubicin chemotherapies. In addition, TLR4 inhibition improves cellular response to Rac/Cdc42 inhibitor, MBQ‐167. Therefore, TLR4‐KD may reduce Rac and NfkB signaling, improving treatment response to MBQ‐167, MBQ‐167/Paclitaxel, and MBQ‐167/Doxorubicin. Other cellular studies, including Rac and NfkB activation assays, are being evaluated in our laboratory.
Triple-negative breast cancer (TNBC) is an aggressive and recurrent type of breast cancer that accounts for over 15% of new diagnoses yearly. Patients with TNBC have limited response to hormonal or targeted therapies due to the lack of ER, PR, and HER2. Therefore, the standard treatment for TNBC is anthracycline/taxane-based chemotherapies, paclitaxel (PXL), and doxorubicin (DOX), for which patients often develop chemoresistance. PXL, particularly, induces metastasis in TNBC patients by activating the Toll-Like Receptor 4 (TLR4)/NFkB signaling pathway. Since there are few targeted therapies for TNBC, there is an urgent need to identify new “druggable” molecular targets. The oncogenic GTPases Rac and Cdc42, and their downstream effector, p-21 Activated Kinase (PAK), play critical roles in TNBC development and metastatic cancer progression. Therefore, we developed MBQ-167 as a potent Rac/Cdc42 inhibitor that decreases tumor cell growth and metastasis in TNBC mouse models with no apparent toxicity. To test the hypothesis that inhibiting Rac/Cdc42 with MBQ-167 will chemosensitize TNBC cells to PXL and DOX, we treated TNBC human cell lines MDA-MB-231 and MDA-MB-468 with different concentrations of MBQ-167 (250 nM-500 nM), PXL (5 nM-10 nM), DOX (250 nM-500 nM), and their combinations. The efficacy of single and combined treatments was determined on cell proliferation with the MTT assay, apoptosis with the Caspase-Glo 3/7 assay, and cell migration with the wound healing assay. In addition, we evaluated the effect of single or combined MBQ-167 (per oral 50 mg/kg, 5X a week) and PXL (IP 10mg/kg, 1X a week) on tumor growth and metastasis in an orthotopic Luciferase tagged-MDA-MB-468 TNBC mouse model. Our in vitro results demonstrate that treatments with MBQ-167, PXL, DOX, and their respective combinations, decreased TNBC cell viability and increased apoptosis compared to vehicle controls. Both combination treatments reduced cell viability and increased apoptosis compared to PXL or DOX alone. Moreover, MBQ-167 was more effective than PXL at reducing MDA-MB-231 cell migration. DOX treatment did not affect cell migration, while combination treatment of DOX with MBQ-167 decreased migration. Moreover, in the mouse model, MBQ-167 significantly reduced MDA-MB-468 mammary tumor growth by 85% compared to vehicle treatments. This decrease in tumor growth was comparable to PXL treatment alone and in combination with MBQ-167. As expected, PXL treatment increased metastasis to the lungs and liver, while MBQ-167 prevented lung and liver metastases and reduced PXL-induced metastasis. Therefore, inhibiting Rac/Cdc42 with MBQ-167 improves the responses to current TNBC chemotherapies, PXL and Dox, and reduces PXL-induced metastasis, making MBQ-167 a potential adjuvant treatment against TNBC. This conclusion will be tested since we recently obtained IND approval from the US FDA for MBQ-167 and plan to conduct clinical trials in TNBC patients. Citation Format: Nilmary Grafals-Ruiz, Ailed M. Cruz-Collazo, Anamaris Torres-Sánchez, Surangani Dharmawardhane. MBQ-167 chemosensitizes triple-negative breast cancer cells to current chemotherapies and reduces paclitaxel-induced metastasis [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-01-05.
Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal forms of cancer. To date, there are few therapies that are efficient against this disease, and patients often develop therapy resistance. The homologous Rho GTPases, Rac and Cdc42, are overexpressed in pancreatic cancer and correlated with poor prognosis. Rho GTPases regulate cell migration/invasion, cell morphology/polarity, and cell survival/viability. Rac and Cdc42 are essential Rho GTPases in oncogenic transformation and invasiveness and govern invasion in both cancer cells and tumor-associated macrophages (TAMs). TAMs are immunosuppressive cells that exacerbate cancer progression via inflammatory responses and crosstalk signaling with malignant cancer cells to promote invasion and immunesuppression. Our laboratory has developed a dual Rac/Cdc42 inhibitor, MBQ-167 (IC50 100nM), as an anticancer agent that recently received IND approval from the US FDA due to its safety and efficacy in breast cancer models. The hypothesis tested in this study is that MBQ-167 will simultaneously target the migration and activity of pancreatic cancer cells and immunosuppressive cells in the tumor microenvironment (TME). To evaluate this, we performed pulldown assays for Rac and Cdc42 activation, MTT cell viability assays, wound-healing assays for cell migration, and phagocytosis assays using human and rat macrophage and human pancreatic cancer cell lines. Results show that MBQ-167 is not toxic to macrophages even at concentrations as high as 10uM. MBQ-167 inhibited Rac1activation by 75% and Cdc42 activation by 40% in THP-1 human macrophages at 500nM. MBQ-167 reduced macrophage migration by 67% at 150nM, and decreased pancreatic cancer cell migration by 60% at 250nM. In addition, MBQ-167 reduced macrophage phagocytosis by 56% at 500nM. This study demonstrates the utility of Rac/Cdc42 inhibition to reduce pancreatic cancer progression in the TME. Citation Format: Anamaris Torres-Sánchez, Michael Rivera-Robles, Stephanie Dorta-Estremera, Suranganie Dharmawardhane. Rac and Cdc42 inhibition on macrophage function in the pancreatic tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2617.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.