BRCA1 deficiency in triple-negative breast cancer: Protein stability as a basis for therapy

Molecular Subtypes and Mechanisms of Breast Cancer: Precision Medicine Approaches for Targeted Therapies

Breast cancer remains one of the most prevalent diseases worldwide, primarily affecting women. Its heterogeneous nature poses a significant challenge in the development of effective and targeted treatments. Molecular characterization has enabled breast cancer to be classified into four main subtypes: luminal A, luminal B, HER2-positive, and triple-negative breast cancer, based on hormone receptor expression and HER2 status. A deeper understanding of these molecular markers and their associated signaling pathways, such as MAPK and PI3K/AKT, is essential for improving prognosis and optimizing treatment strategies. Currently, several therapeutic agents are utilized in neoadjuvant and adjuvant therapies, often in combination with surgical interventions. However, emerging evidence highlights the growing challenge of drug resistance, which significantly limits the efficacy of existing treatments. Addressing this issue may require innovative approaches, including combination therapies and precision medicine strategies, tailored to the molecular profile of each patient. Therefore, a comprehensive understanding of the pathophysiologic mechanisms driving breast cancer progression and resistance is crucial for the development of advanced targeted therapies with greater precision and efficacy. This review aims to explore recent advancements in molecular research related to breast cancer subtypes and provide a critical analysis of current therapeutic approaches within the framework of precision medicine.

Recent Advances in Immunotherapy and Targeted Therapy of Triple Negative Breast Cancer

The truancy of representation of the estrogen, progesterone, and human epidermal growth factor receptors occurs during TNBC. TNBC is recognized for the upper reappearance and has a poorer diagnosis compared with rest breast cancer (BC) types. Presently, as such, no targeted therapy is approved for TNBC and treatment options are subjected to chemotherapy and surgery, which have high mortality rates. Hence, the current article focuses on the scenario of TNBC vital pathways and discusses the latest advances in TNBC treatment, including immune checkpoint inhibitors (ICIs), PARP suppressors, and cancer vaccines. Immunotherapy and ICIs, like PD 1 and PD L1 suppressors, displayed potential in clinical trials (CTs). These suppressors obstruct the mechanisms which allow tumor cells to evade the system thereby boosting the body's defense against TNBC. Immunotherapy, either alone or combined with chemotherapy has demonstrated patient outcomes such as increased survival rates and reduced treatment-related side effects. Additionally, targeted therapy approaches include BRCA/2 mutation poly ribose polymerase inhibitors, Vascular Endothelial Growth Factor Receptor (VEGFR) inhibitors, Epidermal growth factor receptor inhibitors, Fibroblast growth factor inhibitors, Androgen Receptor inhibitors, PIK3/AKT/mTOR pathway inhibitors, Cyclin-dependent kinase (CDK) inhibitors, Notch signaling pathway inhibitors, Signal transducer and activator of transcription 3 (STAT3) signaling pathway inhibitors, Chimeric antigen receptor T (CAR-T) cell therapy, Transforming growth factor (TGF) -β inhibitors, Epigenetic modifications (EPM), Aurora Kinase inhibitors and antibody-drug conjugates. We also highlight ongoing clinical trials and potential future directions for TNBC therapy. Despite the challenges in treating TNBC, recent developments in understanding the molecular and immune characteristics of TNBC have opened up new opportunities for targeted therapies, which hold promise for improving outcomes in this aggressive disease.

Phosphorylation of BRCA1 at serine 1387 plays a critical role in cathepsin S-mediated radiation resistance via BRCA1 degradation and BCL2 stabilization

There is evidence that BRCA1, particularly cytoplasmic BRCA1, plays a significant role in initiating apoptosis through various mechanisms. Maintaining the stability of BRCA1 in cancer cells may be a promising therapeutic strategy for breast cancer, especially in cases of triple-negative breast cancer (TNBC) lacking appropriate therapeutic targets. Previously, it was reported that cathepsin S (CTSS) interacts with the BRCT domain of BRCA1, leading to ubiquitin-mediated degradation. We further investigated the critical role of BRCA1 phosphorylation at Ser1387, which is mediated by ionizing radiation (IR)-induced activation of ATM. This phosphorylation event was identified as a key factor in CTSS-mediated ubiquitin degradation of BRCA1. The functional inhibition of CTSS, using small molecules or a knockdown system, sensitized TNBC cells when exposed to IR by restoring the stability of cytoplasmic BRCA1. The increase in cytoplasmic BRCA1 led to the degradation of anti-apoptotic BCL2, which was responsible for the radiosensitization effect observed with CTSS inhibition. These results suggest that inhibiting CTSS may be an effective strategy for radiosensitization in TNBC cells through BCL2 degradation that is mediated by inhibition of CTSS-induced BRCA1 degradation.

Molecular Docking: An Emerging Tool for Target-Based Cancer Therapy

Molecular docking is a structure-based computational technique that plays a major role in drug discovery. Molecular docking enhances the efficacy of determining the metabolic interaction between two molecules, i.e., the small molecule (ligand) and the target molecule (protein), to find the best orientation of a ligand to its target molecule with minimal free energy in forming a stable complex. By stimulating drug-target interactions, docking helps identify small molecules that might inhibit cancer-promoting proteins, aiding in the development of novel targeted therapies. Molecular docking enables researchers to screen vast reorganization, identifying potential anti-cancer drugs with enhanced specificity and reduced toxicity. The growing importance of molecular docking underscores its potential to revolutionize cancer treatment by accelerating the identification of novel drugs and improving clinical outcomes. As a wide approach, this computational drug design technique can be considered more effective and timesaving than other cancer treatment methods. In this review, we showcase brief information on the role of molecular docking and its importance in cancer research for drug discovery and target identification. Therefore, in recent years, it can be concluded that molecular docking can be scrutinized as one of the novel strategies at the leading edge of cancer-targeting drug discovery.

A non-inferiority, phase III trial of gemcitabine plus capecitabine versus gemcitabine plus carboplatin as first-line therapy and tumor-infiltrating lymphocytes as a prognostic biomarker in patients with advanced triple-negative breast cancer

Background

Gemcitabine plus capecitabine (GX) shows survival benefit and manageable safety in patients with advanced triple-negative breast cancer (TNBC) but there is a paucity of phase III trial evidence. We aimed to compare the efficacy and safety of GX with gemcitabine plus carboplatin (GC) as first-line treatment for patients with advanced TNBC and validate the prognostic value of tumor-infiltrating lymphocytes (TILs).

Methods

Patients with advanced TNBC were randomly assigned 1:1 to receive gemcitabine (1000 mg/m2) on days 1 and 8 plus oral capecitabine (1000 mg/m2 twice a day) on days 1-14, or gemcitabine (1000 mg/m2) on days 1 and 8 plus carboplatin area under curve 2 on days 1 and 8. The primary endpoint was progression-free survival (PFS). TILs were analyzed by immunohistochemistry. The margin used to establish non-inferiority was 1.2.

Results

In all, 187 patients were randomly assigned, with 93 in GX and 94 in GC. Median PFS was 6.1 months in the GX arm compared with 6.3 months in the GC arm. The hazard ratio for PFS was 1.148, and a 95% CI was 0.856-1.539, exceeding the non-inferiority margin of 1.2. The median overall survival (OS) was 21.0 months in the GX arm compared with 21.5 months in the GC arm. The safety profile for the GX regimen was superior to the GC regimen, especially regarding hematological toxicity. Patients with high CD8+ TILs had significantly longer PFS and OS compared with patients with low CD8+ TILs. In the high CD8+ TIL group, the GC arm had prolonged PFS and OS compared with the GX arm.

Conclusion

The trial did not meet the prespecified criteria for the primary endpoint of PFS in patients with advanced TNBC. Moreover, the GC regimen showed better efficacy compared with the GX regimen in patients with high CD8+ TILs. However, the GX regimen should be considered in patients who cannot tolerate hematological toxicity.

Trial registration

ClinicalTrials.gov identifier: NCT02207335.

Triple-Action Therapy: Combining Machine Learning, Docking, and Dynamics to Combat BRCA1-Mutated Breast Cancer

Breast cancer dominates women's mortality, and among other factors, mutations in the BRCA1 gene are significant risk factors. Several approaches are followed to treat the BRCA1 affected cancer patients. However, specific BRCA1 inhibitors are not available till date due to its structural complexity. In addition, there are several limitations associated with the existing drugs used to treat BRCA1-related breast cancer and some side effects. The side effects include symptoms such as hot flashes, joint pain, nausea, fatigue, hair loss, diarrhea, chills, fever, and others. Therefore, advanced approaches needed that can overcome all the limitations and side effects of the current inhibitors. In this study, we adopted a multistep approach to identify potential inhibitors for BRCA1-mutated breast cancer. We used our developed machine learning models to screen potential inhibitors. Molecular docking approach was carried out for the screened hit compounds with BRCA1 and its mutated forms. Two ligands, β-amyrin and Narirutin, has shown significant performance in multiple scoring schemes such as molecular docking and RF score calculations. Molecular dynamics simulations demonstrated the stability of the complexes formed by β-amyrin and Narirutin with BRCA1, with lower RMSD values and less RMSF fluctuations at the binding site locations. Principal component analysis (PCA) and free energy landscape (FEL) further confirmed the compactness and favorable binding of β-Amyrin and Narirutin to BRCA1. These findings suggest that β-amyrin and Narirutin have potential as therapeutic agents against BRCA1-mutated breast cancer.

Advancements in Early Detection and Screening Strategies for Pancreatic Cancer: From Genetic Susceptibility to Novel Biomarkers

Pancreatic cancer is a rare but lethal cancer due to its biologically aggressive nature, advanced stage at the time of diagnosis, and poor response to oncologic therapies. The risk of pancreatic cancer is significantly higher to 5% in certain high-risk individuals with inherited genetic susceptibility. Screening for pancreatic cancer in these individuals from high-risk groups can help with the early detection of pancreatic cancer as well as the detection of precursor lesions leading to early surgical resection and improved overall outcomes. The advancements in radiological imaging as well as advanced endoscopic procedures has made a significant impact on the early diagnosis, surveillance, and staging of pancreatic cancer. There is also a significant advancement in the development of biomarkers for the early detection of pancreatic cancer, which has also led to the development of liquid biopsy, allowing for microRNA detection in serum and circulating tumor cells. Various societies and organizations have provided guidelines for pancreatic cancer screening and surveillance in high-risk individuals. In this review, we aim to discuss the hereditary risk factors for developing pancreatic cancer, summarize the screening recommendations by different societies, and discuss the development of novel biomarkers and areas for future research in pancreatic cancer screening for high-risk individuals.

Aqueous Extracts of Ocimum gratissimum Sensitize Hepatocellular Carcinoma Cells to Cisplatin through BRCA1 Inhibition

Ocimum gratissimum (O. gratissimum), a medicinal herb with antifungal and antiviral activities, has been found to prevent liver injury and liver fibrosis and induce apoptosis in hepatocellular carcinoma (HCC) cells. In this study, we evaluated the effect of aqueous extracts of O. gratissimum (OGE) on improving the efficacy of chemotherapeutic drugs in HCC cells. Proteomic identification and functional assays were used to uncover the critical molecules responsible for OGE-induced sensitization mechanisms. The antitumor activity of OGE in combination with a chemotherapeutic drug was evaluated in a mouse orthotopic tumor model, and serum biochemical tests were further utilized to validate liver function. OGE sensitized HCC cells to the chemotherapeutic drug cisplatin. Proteomic analysis and Western blotting validation revealed the sensitization effect of OGE, likely achieved through the inhibition of breast cancer type 1 susceptibility protein (BRCA1). Mechanically, OGE treatment resulted in BRCA1 protein instability and increased proteasomal degradation, thereby synergistically increasing cisplatin-induced DNA damage. Moreover, OGE effectively inhibited cell migration and invasion, modulated epithelial-to-mesenchymal transition (EMT), and impaired stemness properties in HCC cells. The combinatorial use of OGE enhanced the efficacy of cisplatin and potentially restored liver function in a mouse orthotopic tumor model. Our findings may provide an alternate approach to improving chemotherapy efficacy in HCC.

Radiosensitizing effect of a novel CTSS inhibitor by enhancing BRCA1 protein stability in triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) patients harboring wild-type breast cancer susceptibility gene 1 (BRCA1) account for most TNBC patients but lack adequate targeted therapeutic options. Although radiotherapy (RT) is the primary treatment modality for TNBC patients, radioresistance is one of the major challenges. RT-induced increase in cathepsin S (CTSS) causes radioresistance through suppressing BRCA1-mediated apoptosis of tumor cells, which was induced by CTSS-mediated degradation of BRCA1. Targeting CTSS may provide a novel therapeutic opportunity for TNBC patients. Publicly available data and human tissue microarray slides were analyzed to investigate the relationship between CTSS and BRCA1 in breast cancer patients. A CTSS enzyme assay and in silico docking analysis were conducted to identify a novel CTSS inhibitor. RO5461111 was used first to confirm the concept of targeting CTSS for radiosensitizing effects. The MDA-MB-231 TNBC cell line was used for in vitro and in vivo assays. Western blotting, promoter assay, cell death assay, clonogenic survival assay, and immunohistochemistry staining were conducted to evaluate novel CTSS inhibitors. CTSS inhibitors were further evaluated for their additional benefit of inhibiting cell migration. A novel CTSS inhibitor, TS-24, increased BRCA1 protein levels and showed radiosensitization in TNBC cells with wild-type BRCA1 and in vivo in a TNBC xenograft mouse model. These effects were attributed by BRCA1-mediated apoptosis facilitated by TS-24. Furthermore, TS-24 demonstrated the additional effect of inhibiting cell migration. Our study suggests that employing CTSS inhibitors for the functional restoration of BRCA1 to enhance RT-induced apoptosis may provide a novel therapeutic opportunity for TNBC patients harboring wild-type BRCA1.

maGENEgerZ: An Efficient Artificial Intelligence-Based Framework Can Extract More Expressed Genes and Biological Insights Underlying Breast Cancer Drug Response Mechanism

Understanding breast cancer drug response mechanisms can play a crucial role in improving treatment outcomes and survival rates. Existing bioinformatics-based approaches are far from perfect and do not adopt computational methods based on advanced artificial intelligence concepts. Therefore, we introduce a novel computational framework based on an efficient support vector machine (esvm) working as follows: First, we downloaded and processed three gene expression datasets related to breast cancer responding and non-responding to treatments from the gene expression omnibus (GEO) according to the following GEO accession numbers: GSE130787, GSE140494, and GSE196093. Our method esvm is formulated as a constrained optimization problem in its dual form as a function of λ. We recover the importance of each gene as a function of λ, y, and x. Then, we select p genes out of n, which are provided as input to enrichment analysis tools, Enrichr and Metascape. Compared to existing baseline methods, including deep learning, results demonstrate the superiority and efficiency of esvm, achieving high-performance results and having more expressed genes in well-established breast cancer cell lines, including MD-MB231, MCF7, and HS578T. Moreover, esvm is able to identify (1) various drugs, including clinically approved ones (e.g., tamoxifen and erlotinib); (2) seventy-four unique genes (including tumor suppression genes such as TP53 and BRCA1); and (3) thirty-six unique TFs (including SP1 and RELA). These results have been reported to be linked to breast cancer drug response mechanisms, progression, and metastasizing. Our method is available publicly on the maGENEgerZ web server.

Chemoresistance to additive PARP/PI3K dual inhibition in triple-negative breast cancer cell lines is associated with adaptive stem cell-like prevalence

Cancer stem-like cells (CSCs) are posited to exhibit specialized oncogenic capacity to drive malignancies. CSCs are distinguished by enhanced hallmarks of cancer, including apoptosis avoidance, phenotypic plasticity and aberrant growth pathway signaling. Standard-of-care chemotherapies targeted to rapidly cycling cells routinely fail to eliminate this resistant subpopulation, leading to disease recurrence and metastasis. Triple-negative breast cancer (TNBC), a highly aggressive subtype of breast cancer, is enriched for tumor-propagating CD44+/CD24-/low CSCs, which are poorly ablated by chemotherapeutics and are associated with poor prognosis. CD44 governs sustained PI3K signaling in breast cancer, which is essential for CSC maintenance. PI3K inhibition can elicit DNA damage and down-regulate BRCA1 expression, which in turn enhance the synthetic lethality of PARP inhibitors. Here, we examined a dual chemotherapeutic approach targeting these pathways by combining a pan-PI3K inhibitor (Buparlisib) and a PARP1 inhibitor (Olaparib) on a panel of TNBC cell lines with distinct mutational profiles and proportions of CSCs. We observed differential sensitivity to this dual inhibition strategy and varying cellular stress and resistance responses across eight TNBC lines. The dual chemotherapeutic effect is associated with a reduction in S-phase cells, an increased in apoptotic cells and elevated expression of cleaved PARP, indicating a provoked replicative stress response. We observed that PARP/PI3K inhibition efficacy was potentiated by repeated administration in some TNBC lines and identified critical treatment schedules, which further potentiated the dual chemotherapeutic effect. Dual inhibition induced small but significant increases in CSC relative abundance as marked by CD44+/CD24-/low or ALDH1+ cells and increased stress and survival signaling in multiple TNBC cell lines, suggesting this sub-population contributes to TNBC chemoresistance. These results suggest the additive effects of PARP and PI3K inhibition against CSC phenotypes may be enhanced by temporally-staged administration in TNBC cells.

Updates on Triple-Negative Breast Cancer in Type 2 Diabetes Mellitus Patients: From Risk Factors to Diagnosis, Biomarkers and Therapy

Triple-negative breast cancer (TNBC) is usually the most malignant and aggressive mammary epithelial tumor characterized by the lack of expression for estrogen receptors and progesterone receptors, and the absence of epidermal growth factor receptor (HER)2 amplification. Corresponding to 15-20% of all breast cancers and well-known by its poor clinical outcome, this negative receptor expression deprives TNBC from targeted therapy and makes its management therapeutically challenging. Type 2 diabetes mellitus (T2DM) is the most common ageing metabolic disorder due to insulin deficiency or resistance resulting in hyperglycemia, hyperinsulinemia, and hyperlipidemia. Due to metabolic and hormonal imbalances, there are many interplays between both chronic disorders leading to increased risk of breast cancer, especially TNBC, diagnosed in T2DM patients. The purpose of this review is to provide up-to-date information related to epidemiology and clinicopathological features, risk factors, diagnosis, biomarkers, and current therapy/clinical trials for TNBC patients with T2DM compared to non-diabetic counterparts. Thus, in-depth investigation of the diabetic complications on TNBC onset, development, and progression and the discovery of biomarkers would improve TNBC management through early diagnosis, tailoring therapy for a better outcome of T2DM patients diagnosed with TNBC.