Nrh L11R single nucleotide polymorphism, a new prediction biomarker in breast cancer, impacts endoplasmic reticulum-dependent Ca2+ traffic and response to neoadjuvant chemotherapy

The BCL2 family: from apoptosis mechanisms to new advances in targeted therapy

The B cell lymphoma 2 (BCL2) protein family critically controls apoptosis by regulating the release of cytochrome c from mitochondria. In this cutting-edge review, we summarize the basic biology regulating the BCL2 family including canonical and non-canonical functions, and highlight milestones from basic research to clinical applications in cancer and other pathophysiological conditions. We review laboratory and clinical development of BH3-mimetics as well as more recent approaches including proteolysis targeting chimeras (PROTACs), antibody-drug conjugates (ADCs) and tools targeting the BH4 domain of BCL2. The first BCL2-selective BH3-mimetic, venetoclax, showed remarkable efficacy with manageable toxicities and has transformed the treatment of several hematologic malignancies. Following its success, several chemically similar BCL2 inhibitors such as sonrotoclax and lisaftoclax are currently under clinical evaluation, alone and in combination. Genetic analysis highlights the importance of BCL-XL and MCL1 across different cancer types and the possible utility of BH3-mimetics targeting these proteins. However, the development of BH3-mimetics targeting BCL-XL or MCL1 has been more challenging, with on-target toxicities including thrombocytopenia for BCL-XL and cardiac toxicities for MCL1 inhibitors precluding clinical development. Tumor-specific BCL-XL or MCL1 inhibition may be achieved by novel targeting approaches using PROTACs or selective drug delivery strategies and would be transformational in many subtypes of malignancy. Taken together, we envision that the targeting of BCL2 proteins, while already a success story of translational research, may in the foreseeable future have broader clinical applicability and improve the treatment of multiple diseases.

BCL-B Promotes Lung Cancer Invasiveness by Direct Inhibition of BOK

Expression of BCL-B, an anti-apoptotic BCL-2 family member, is correlated with worse survival in lung adenocarcinomas. Here, we show that BCL-B can mitigate cell death initiation through interaction with the effector protein BOK. We found that this interaction can promote sublethal mitochondrial outer membrane permeabilization (MOMP) and consequently generate apoptosis-flatliners, which represent a source of drug-tolerant persister cells (DTPs). The engagement of endothelial-mesenchymal-transition (EMT) further promotes cancer cell invasiveness in such DTPs. Our results reveal that BCL-B fosters cancer cell aggressiveness by counteracting complete MOMP.

Recent advances in canonical versus non-canonical Ca2+-signaling-related anti-apoptotic Bcl-2 functions and prospects for cancer treatment

Cell fate is tightly controlled by a continuous balance between cell survival and cell death inducing mechanisms. B-cell lymphoma 2 (Bcl-2)-family members, composed of effectors and regulators, not only control apoptosis at the level of the mitochondria but also by impacting the intracellular Ca2+ homeostasis and dynamics. On the one hand, anti-apoptotic protein Bcl-2, prevents mitochondrial outer membrane permeabilization (MOMP) by scaffolding and neutralizing proapoptotic Bcl-2-family members via its hydrophobic cleft (region composed of BH-domain 1-3). On the other hand, Bcl-2 suppress pro-apoptotic Ca2+ signals by binding and inhibiting IP3 receptors via its BH4 domain, which is structurally exiled from the hydrophobic cleft by a flexible loop region (FLR). As such, Bcl-2 prevents excessive Ca2+ transfer from ER to mitochondria. Whereas regulation of both pathways requires different functional regions of Bcl-2, both seem to be connected in cancers that overexpress Bcl-2 in a life-promoting dependent manner. Here we discuss the anti-apoptotic canonical and non-canonical role, via calcium signaling, of Bcl-2 in health and cancer and evolving from this the proposed anti-cancer therapies with their shortcomings. We also argue how some cancers, with the major focus on diffuse large B-cell lymphoma (DLBCL) are difficult to treat, although theoretically prime marked for Bcl-2-targeting therapeutics. Further work is needed to understand the non-canonical functions of Bcl-2 also at organelles beyond the mitochondria, the interaction partners outside the Bcl-2 family as well as their ability to target or exploit these functions as therapeutic strategies in diseases.

Causal effects and metabolites mediators between immune cell and risk of breast cancer: a Mendelian randomization study

Introduction: The incidence and mortality of female breast cancer remain high, and the immune microenvironment of breast cancer has undergone significant alterations. However, the impact of blood immune cell levels on the risk of breast cancer is not fully understood. Therefor this study aims to investigate the causal relationship between blood immune cell levels and the risk of breast cancer. Methods: A Mendelian randomization (MR) analysis was employed to assess the causal relationship between immune cells and the risk of breast cancer, as along with their potential mediating factors. Genetic statistics of metabolites breast cancer and immune cells were obtained from the GWAS Catalog, while the genome-wide association study (GWAS) statistics of breast cancer were extracted from the UK biobank. Two-sample MR analysis were performed using inverse-variance weighted (IVW) to ascertain the causal association between immune cells and the risk of breast cancer. Furthermore, 1,400 metabolites were analyzed for their mediating role between immune cells and the risk of breast cancer. Results: MR analysis through IVW method revealed that genetically predicted CD24+ CD27+ B cells were associated with a decreased risk of breast cancer (OR = 0.9978, 95% CI: 0.996-0.999, p = 0.001), while IgD- CD38+ B cells were linked to an increased risk of breast cancer (OR = 1.002, 95% CI: 1.001-1.004, p = 0.005). Additional CD14+ CD16+ monocytes were associated with an increased risk of breast cancer (OR = 1.000, 95% CI: 1.000-1.001, p = 0.005). Mediation analysis revealed a positive causal relationship between IgD- CD38+ B cells and Glycerate levels, with the latter also exhibiting a positive causal relationship with the risk of breast cancer (p < 0.05). Conversely, IgD- CD38+ B cells displayed a negative causal relationship with Succinoyltaurine levels, and the latter also demonstrated a negative causal relationship with the risk of breast cancer (p < 0.05). Conclusion: This MR study provides novel genetic evidence supporting a causal relationship between IgD- CD38+ B cells and the risk of BC. Moreover, it is identified that IgD- CD38+ B cells contribute to an increased risk of BC through both positive and negative mediation effects involving Glycerate and Succinoyltaurine.

Bcl-B: an "unknown" protein of the Bcl-2 family

Bcl-B is a poorly understood protein of the Bcl-2 family that is highly expressed in many healthy tissues and tumor types. Bcl-B is considered an antiapoptotic protein, but many reports have revealed its contradictory roles in different cancer types. In this mini-review, we elucidate the functions of Bcl-B in normal conditions and various pathologies, its regulation of programmed cell death, its oncogene/oncosuppressor activity in tumorigenesis, its impact on drug-acquired resistance, and possible approaches to inhibit Bcl-B.