Therapeutic and Mechanistic Perspectives of Protein Complexes in Breast Cancer

Targeting HER2 in solid tumors: Unveiling the structure and novel epitopes

Human epidermal growth factor receptor-2 (HER2) is overexpressed in various solid tumor types, acting as an established therapeutic target. Over the last three decades, the fast-paced development of diverse HER2-targeted agents, notably marked by the introduction of the antibody-drug conjugate (ADC), yielding substantial improvements in survival rates. However, resistance to anti-HER2 treatments continues to pose formidable challenges. The complex structure and dynamic dimerization properties of HER2 create significant hurdles in the development of novel targeted therapeutics. In this review, we synthesize the latest insights into the structural intricacies of HER2 and present an unprecedented overview of the epitope characteristics of HER2-targeted antibodies and their derivatives. Furthermore, we delve into the correlation between anti-HER2 antibody binding epitopes and their respective functions, with a particular focus on their efficacy against resistant tumors. In addition, we highlight the potential of emerging anti-HER2 agents that target specific sites or non-overlapping epitopes, poised to transform the therapeutic landscape for HER2-positive tumors in the foreseeable future.

PROTAC: Novel degradable approach for different targets to treat breast cancer

The revolutionary Proteolysis Targeting Chimera (PROTACs) have the exciting potential to reshape the pharmaceutical industry landscape by leveraging the ubiquitin-proteasome system for targeted protein degradation. Breast cancer, the most prevalent cancer in women, could be treated using PROTAC therapy. Although substantial work has been conducted, there is not yet a comprehensive overview or progress update on PROTAC therapy for breast cancer. Hence, in this article, we've compiled recent research progress focusing on different breast cancer target proteins, such as estrogen receptor (ER), BET, CDK, HER2, PARP, EZH2, etc. This resource aims to serve as a guide for future PROTAC-based breast cancer treatment design.

Exploratory comparisons between different anti-mitotics in clinically-used drug combination in triple negative breast cancer

Triple-negative breast cancer (TNBC) constitutes a very aggressive type of breast cancer with few options of cytotoxic chemotherapy available for them. A chemotherapy regimen comprising of doxorubicin hydrochloride and cyclophosphamide, followed by paclitaxel, known as AC-T, is approved for usage as an adjuvant treatment for this type of breast cancer. In this study we aimed to elucidate the role of KIF11 in TNBC progression throughout its inhibition by two synthetic small molecules containing the DHPM core (dihydropyrimidin-2(1H)-ones or -thiones), with the hypothesis that these inhibitors could be an interesting option of antimitotic drug used alone or as adjuvant therapy in association with AC. For this purpose, we evaluated the efficacy of DHPMs used as monotherapy or in combination with doxorubicin and cyclophosphamide, in Balbc-nude mice bearing breast cancer induced by MDA-MB-231, having AC-T as positive control. Our data provide extensive evidence to demonstrate that KIF11 inhibitors showed pronounced antitumor activity, acting in key points of tumorigenesis and cancer progression in in vivo xenograft model of triple negative breast cancer, like down-regulation of KIF11 and ALDH1-A1. Moreover, they didn’t show the classic peripheral neuropathy characterized by impaired mobility, as it is common with paclitaxel use. These results suggest that the use of a MAP inhibitor in breast cancer regimen treatment could be a promising strategy to keep antitumoral activity reducing the side effects.

Long Noncoding RNA TCONS_00068220 Promotes Breast Cancer Progression by Regulating Epithelial-Mesenchymal Transition Marker E-Cadherin

BACKGROUND Long noncoding RNAs (lncRNAs) play essential roles in the regulation of breast cancer development. We herein investigated the potential role of lncRNA TCONS_00068220 in breast cancer pathogenesis. MATERIAL AND METHODS The expression levels of TCONS_00068220 in breast cancer tissues were measured by qRT-PCR. Afterwards, TCONS_00068220 was (1) overexpressed in MCF-7 breast cancer cells, and (2) silenced in MDA-MB-231 cells. Then, CCK-8 and transwell assays were conducted to detect the impact of TCONS_00068220 on cell proliferation, migration, and invasion. The expression of the epithelial-mesenchymal transition (EMT) marker E-cadherin was detected by western blot assay after upregulation or downregulation of TCONS_00068220. RESULTS TCONS_00068220 was remarkably upregulated in breast cancer tissues compared with non-cancerous tissues. In addition, TCONS_00068220 level was significantly correlated with lymphatic metastasis, Ki67 index, clinical stage, and differentiation grade. All breast cancer cell lines displayed a higher expression level of TCONS_00068220 compared with the normal breast epithelial cell line MCF-10A. Furthermore, enhanced expression of TCONS_00068220 in MCF-7 cells promoted cell proliferation, migration, invasion, and EMT, whereas TCONS_00068220 knockdown in MDA-MB-231 cells led to the opposite results. E-cadherin was negatively regulated by TCONS_00068220 in both breast cancer tissues and cell lines. Finally, TCONS_00068220 regulated MCF-7 and MDA-MB-231 cell behaviors by downregulating E-cadherin. CONCLUSIONS TCONS_00068220 promotes breast cancer cell proliferation, migration, and invasion, while facilitating the process of EMT by interacting with E-cadherin and suppressing its expression. Therefore, it may potentially serve as an oncogene in breast cancer progression.