Bcl-3 regulates UVB-induced apoptosis

Enhancing cell death in B-cell malignancies through targeted inhibition of Bcl-3

The t(14;19)(q32;q13) is a rare recurring translocation found in B-cell lymphoproliferative malignancies, involving the Bcl-3 gene. This chromosomal translocation is often found in patients under the age of 50 and causes a more progressive disease. The Bcl-3 gene encodes a protein belonging to the IκB family of proteins, which tightly regulates NFκB signaling by acting as an activator or repressor of transcription. Previously, we developed a second-generation Bcl-3 inhibitor that could directly interfere with Bcl-3 signaling pathway, resulting in reduced melanoma cell proliferation, invasion, and migration. The present study aimed to investigate the effect of a Bcl-3 inhibitor on B-cell lymphoma and leukemia cells. It was found that treatment of cells with this inhibitor caused a decrease in cell proliferation and cell survival. Furthermore, Bcl-3 inhibition in B-cell malignant cells resulted in the loss of mitochondrial membrane potential and functionality, as well as the increased expression of cleaved caspase 3, indicating that cell death occurs through the intrinsic apoptotic pathway. This observation is further supported by reduced expression of cIAP1 protein 1 (cIAP1) upon treatment of cancer cells. Given the current lack of clinical advancements targeting Bcl-3 in oncology, this opens a novel avenue for the development and investigation of highly specific therapeutic interventions against B-cell malignancies.

Multifaceted roles for BCL3 in cancer: a proto-oncogene comes of age

In the early 1990's a group of unrelated genes were identified from the sites of recurring translocations in B-cell lymphomas. Despite sharing the nomenclature 'Bcl', and an association with blood-borne cancer, these genes have unrelated functions. Of these genes, BCL2 is best known as a key cancer target involved in the regulation of caspases and other cell viability mechanisms. BCL3 on the other hand was originally identified as a non-canonical regulator of NF-kB transcription factor pathways - a signaling mechanism associated with important cell outcomes including many of the hallmarks of cancer. Most of the early investigations into BCL3 function have since focused on its role in NF-kB mediated cell proliferation, inflammation/immunity and cancer. However, recent evidence is coming to light that this protein directly interacts with and modulates a number of other signaling pathways including DNA damage repair, WNT/β-catenin, AKT, TGFβ/SMAD3 and STAT3 - all of which have key roles in cancer development, metastatic progression and treatment of solid tumours. Here we review the direct evidence demonstrating BCL3's central role in a transcriptional network of signaling pathways that modulate cancer biology and treatment response in a range of solid tumour types and propose common mechanisms of action of BCL3 which may be exploited in the future to target its oncogenic effects for patient benefit.

BCL-3 loss sensitises colorectal cancer cells to DNA damage by targeting homologous recombination

The proto-oncogene BCL-3 is upregulated in a subset of colorectal cancers (CRC), where it has been shown to enhance tumour cell survival. However, although increased expression correlates with poor patient prognosis, the role of BCL-3 in determining therapeutic response remains largely unknown. In this study, we use combined approaches in multiple cell lines and pre-clinical mouse models to investigate the function of BCL-3 in the DNA damage response. We show that suppression of BCL-3 increases γH2AX foci formation and decreases homologous recombination in CRC cells, resulting in reduced RAD51 foci number and increased sensitivity to PARP inhibition. Importantly, a similar phenotype is seen in Bcl3-/- mice, where Bcl3-/- mouse crypts also exhibit sensitivity to DNA damage with increased γH2AX foci compared to wild type mice. Additionally, Apc.Kras-mutant x Bcl3-/- mice are more sensitive to cisplatin chemotherapy compared to wild type mice. Taken together, our results identify BCL-3 as a regulator of the cellular response to DNA damage and suggests that elevated BCL-3 expression, as observed in CRC, could increase resistance of tumour cells to DNA damaging agents including radiotherapy. These findings offer a rationale for targeting BCL-3 in CRC as an adjunct to conventional therapies and suggest that BCL-3 expression in tumours could be a useful biomarker in stratification of rectal cancer patients for neo-adjuvant chemoradiotherapy.

Bcl-3: A Double-Edged Sword in Immune Cells and Inflammation

The NF-κB transcription factor family controls the transcription of many genes and regulates a number of pivotal biological processes. Its activity is regulated by the IκB family of proteins. Bcl-3 is an atypical member of the IκB protein family that regulates the activity of nuclear factor NF-κB. It can promote or inhibit the expression of NF-κB target genes according to the received cell type and stimulation, impacting various cell functions, such as proliferation and differentiation, induction of apoptosis and immune response. Bcl-3 is also regarded as an environment-dependent cell response regulator that has dual roles in the development of B cells and the differentiation, survival and proliferation of Th cells. Moreover, it also showed a contradictory role in inflammation. At present, in addition to the work aimed at studying the molecular mechanism of Bcl-3, an increasing number of studies have focused on the effects of Bcl-3 on inflammation, immunity and malignant tumors in vivo. In this review, we focus on the latest progress of Bcl-3 in the regulation of the NF-κB pathway and its extensive physiological role in inflammation and immune cells, which may help to provide new ideas and targets for the early diagnosis or targeted treatment of various inflammatory diseases, immunodeficiency diseases and malignant tumors.

5-HTP decreases goat mammary epithelial cells apoptosis through MAPK/ERK/Bcl-3 pathway

Serotonin (5-HT) is a monoamine and it could regulate cell growth by its receptors working on signaling pathways. 5-HTP is the precursor of 5-HT that help 5-HT synthesis. B cell leukemia/lymphoma 3 (Bcl-3) involved in cell death and proliferation through mitogen activated protein kinase (MAPK) pathway. However, there is little information about the effects of MAPK/Bcl-3 on apoptosis of goat mammary gland epithelial cells (GMECs). The aim of this study is to explore the interaction among 5-HTP, MAPK and Bcl-3 in GMEC apoptosis. In this study, 5-HTP treatment decreased cell apoptosis and promoted phosphorylation of ERK1/2 in GMEC. We also found that the activation and inhibition of ERK1/2 could affect GMEC apoptosis. The Annexin V-FITC/PI staining and western blotting results suggested that 5-HTP decreased GMEC apoptosis through ERK1/2 signaling pathway. And the results of RT-qPCR and western blotting demonstrated that both 5-HTP and ERK1/2 positively regulated Bcl-3 expression. Sum up all the results, we could draw the conclusion that 5-HTP decreased GMEC apoptosis through MAPK/ERK/Bcl-3 pathway.

De novo transcriptome analysis and gene expression profiling of fish scales isolated from Carassius auratus during space flight: Impact of melatonin on gene expression in response to space radiation

Astronauts are inevitably exposed to two major risks during space flight, microgravity and radiation. Exposure to microgravity has been discovered to lead to rapid and vigorous bone loss due to elevated osteoclastic activity. In addition, long‑term exposure to low‑dose‑rate space radiation was identified to promote DNA damage accumulation that triggered chronic inflammation, resulting in an increased risk for bone marrow suppression and carcinogenesis. In our previous study, melatonin, a hormone known to regulate the sleep‑wake cycle, upregulated calcitonin expression levels and downregulated receptor activator of nuclear factor‑κB ligand expression levels, leading to improved osteoclastic activity in a fish scale model. These results indicated that melatonin may represent a potential drug or lead compound for the prevention of bone loss under microgravity conditions. However, it is unclear whether melatonin affects the biological response induced by space radiation. The aim of the present study was to evaluate the effect of melatonin on the expression levels of genes responsive to space radiation. In the present study, to support the previous data regarding de novo transcriptome analysis of goldfish scales, a detailed and improved experimental method (e.g., PCR duplicate removal followed by de novo assembly, global normalization and calculation of statistical significance) was applied for the analysis. In addition, the transcriptome data were analyzed via global normalization, functional categorization and gene network construction to determine the impact of melatonin on gene expression levels in irradiated fish scales cultured in space. The results of the present study demonstrated that melatonin treatment counteracted microgravity‑ and radiation‑induced alterations in the expression levels of genes associated with DNA replication, DNA repair, proliferation, cell death and survival. Thus, it was concluded that melatonin may promote cell survival and ensure normal cell proliferation in cells exposed to space radiation.

The role of B-Cell Lymphoma-3 (BCL-3) in enabling the hallmarks of cancer: implications for the treatment of colorectal carcinogenesis

With its identification as a proto-oncogene in chronic lymphocytic leukaemia and central role in regulating NF-κB signalling, it is perhaps not surprising that there have been an increasing number of studies in recent years investigating the role of BCL-3 (B-Cell Chronic Lymphocytic Leukaemia/Lymphoma-3) in a wide range of human cancers. Importantly, this work has begun to shed light on our mechanistic understanding of the function of BCL-3 in tumour promotion and progression. Here, we summarize the current understanding of BCL-3 function in relation to the characteristics or traits associated with tumourigenesis, termed ‘Hallmarks of Cancer’. With the focus on colorectal cancer, a major cause of cancer related mortality in the UK, we describe the evidence that potentially explains why increased BCL-3 expression is associated with poor prognosis in colorectal cancer. As well as promoting tumour cell proliferation, survival, invasion and metastasis, a key emerging function of this proto-oncogene is the regulation of the tumour response to inflammation. We suggest that BCL-3 represents an exciting new route for targeting the Hallmarks of Cancer; in particular by limiting the impact of the enabling hallmarks of tumour promoting inflammation and cell plasticity. As BCL-3 has been reported to promote the stem-like potential of cancer cells, we suggest that targeting BCL-3 could increase the tumour response to conventional treatment, reduce the chance of relapse and hence improve the prognosis for cancer patients.