BCLAF1 binds SPOP to stabilize PD-L1 and promotes the development and immune escape of hepatocellular carcinoma.

Interaction between programmed death-1 (PD-1) ligand 1 (PD-L1) on tumor cells and PD-1 on T cells allows tumor cells to evade T cell-mediated immune surveillance. Strategies targeting PD-1/PD-L1 have shown clinical benefits in a variety of cancers. However, limited response rates in hepatocellular carcinoma (HCC) have prompted us to investigate the molecular regulation of PD-L1. Here, we identify B cell lymphoma-2-associated transcription factor 1 (BCLAF1) as a key PD-L1 regulator in HCC. Specifically, BCLAF1 interacts with SPOP, an E3 ligase that mediates the ubiquitination and degradation of PD-L1, thereby competitively inhibiting SPOP-PD-L1 interaction and subsequent ubiquitination and degradation of PD-L1. Furthermore, we determined an SPOP-binding consensus (SBC) motif mediating the BCLAF1-SPOP interaction on BCLAF1 protein and mutation of BCLAF1-SBC motif disrupts the regulation of the SPOP-PD-L1 axis. In addition, BCLAF1 expression was positively correlated with PD-L1 expression and negatively correlated with biomarkers of T cell activation, including CD3 and CD8, as well as with the level of immune cell infiltration in HCC tissues. Besides, BCLAF1 depletion leads to a significant reduction of PD-L1 expression in vitro, and this reduction of PD-L1 promoted T cell-mediated cytotoxicity. Notably, overexpression of BCLAF1 sensitized tumor cells to checkpoint therapy in an in vitro HCC cells-Jurkat cells co-culture model, whereas BCLAF1-SBC mutant decreased tumor cell sensitivity to checkpoint therapy, suggesting that BCLAF1 and its SBC motif serve as a novel therapeutic target for enhancing anti-tumor immunity in HCC.

Bclaf1 regulates c-FLIP expression and protects cells from TNF-induced apoptosis and tissue injury.

TNF stimulation generates pro-survival signals through activation of NF-κB that restrict the build-in death signaling triggered by TNF. The competition between TNF-induced survival and death signals ultimately determines the fate of a cell. Here, we report the identification of Bclaf1 as a novel component of the anti-apoptotic program of TNF. Bclaf1 depletion in multiple cells sensitizes cells to TNF-induced apoptosis but not to necroptosis. Bclaf1 exerts its anti-apoptotic function by promoting the transcription of CFLAR, a caspase 8 antagonist, downstream of NF-κB activation. Bclaf1 binds to the p50 subunit of NF-κB, which is required for Bclaf1 to stimulate CFLAR transcription. Finally, in Bclaf1 siRNA administered mice, TNF-induced small intestine injury is much more severe than in control mice with aggravated signs of apoptosis and pyroptosis. These results suggest Bclaf1 is a key regulator in TNF-induced apoptosis, both in vitro and in vivo.

Pan-Cancer Analysis Identifies BCLAF1 as a Potential Biomarker for Renal Cell Carcinoma.

B-cell lymphoma-2-associated transcription factor 1 (BCLAF1) is a versatile protein involved in the regulation of gene transcription and post-transcriptional processing. Although BCLAF1 exerts a broad tumor suppressor effect or tumor promoter effect in many cancer types, the specific roles concerning its expression levels, and its impact on tumorigenesis in Renal cell carcinoma (RCC) remain unclear. Here, we utilized the Cancer Genome Atlas (TCGA) and Genotype Tissue Expression (GTEx) datasets alongside R software and online tools to unravel the specific roles of BCLAF1 in 33 cancer types, including its expression levels, tumor immune and molecular subtypes, and its correlation with prognosis, diagnosis, DNA methylation, and immune microenvironment. Additionally, we carried out cell biology experiments to independently investigate the expression of BCLAF1 in RCC and its effects on tumor progression. BCLAF1 was differentially expressed in tumor tissues compared to normal tissues across various cancer types and was also differentially expressed in different immune and molecular subtypes. In RCC, patients with high BCLAF1 expression had a better prognosis and BCLAF1 was tightly correlated with the stage, gender, and histological grade of patients. Furthermore, BCLAF1 had higher DNA methylation levels and higher immune infiltration levels in tumor tissues. Additionally, cell functional experiments confirmed the low expression of BCLAF1 in RCC and that BCLAF1 significantly inhibited the proliferation, migration, and invasion, while inducing apoptosis and cell cycle arrest in RCC cells in vitro. Our study under-scored the potential of BCLAF1 as an important actor in tumorigenesis, especially concerning RCC where it may serve as an effective prognostic marker.

BCLAF1 is Expressed as a Potential Anti-oncogene in Bile Duct Cancer.

Validating the role of BCLAF1 in the development of Bile Duct Cancer. Differential expression of BCLAF1 in Bile Duct Cancer and normal tissues was analyzed bioinformatically, and immuno-infiltration analysis was performed by R. We also derived the correlation between the expression of BCLAF1 and HIF-1α by bioinformatics analysis and validated it by Western Blotting, qRT-PCR and scratch assays before and after hypoxia. Through bioinformatics analysis, we found that BCLAF1 mRNA was significantly higher in the tumor tissues of Bile Duct Cancer. The high expression of BCLAF1 implied a more advanced stage but a lower mortality rate. KEGG and GO enrichment analysis showed that BCLAF1 overexpression in Bile Duct Cancer was mainly associated with histone modification, peptidyl lysine modification, and macromolecular methylation. We used the TIMER algorithm to show that BCLAF1 expression in Bile Duct Cancer is associated with immune cell infiltration, which affects tumor progression and patient prognosis. We confirmed by normoxia and hypoxia qRT-PCR, Western Blotting and scratch assays that BCLAF1 and HIF-1α expression are positively correlated and that BCLAF1 may be expressed as anti-oncogene in Bile Duct Cancer. These findings demonstrate that BCLAF1 may act as anti-oncogene in Bile Duct Cancer and may be involved in immune cell infiltration in Bile Duct Cancer, suppressing the expression of HIF-1α.

TET2-BCLAF1 transcription repression complex epigenetically regulates the expression of colorectal cancer gene Ascl2 via methylation of its promoter.

Ascl2 has been shown to be involved in tumorigenesis in colorectal cancer (CRC), although its epigenetic regulatory mechanism is largely unknown. Here, we found that methylation of the Ascl2 promoter (bp -1670 ∼ -1139) was significantly increased compared to the other regions of the Ascl2 locus in CRC cells and was associated with elevated Ascl2 mRNA expression. Furthermore, we found that promoter methylation was predictive of CRC patient survival after analyzing DNA methylation data, RNA-Seq data, and clinical data of 410 CRC patient samples from the MethHC database, the MEXPRESS database, and the Cbioportal website. Using the established TET methylcytosine dioxygenase 2 (TET2) knockdown and ectopic TET2 catalytic domain-expression cell models, we performed glucosylated hydroxymethyl-sensitive quatitative PCR (qPCR), real-time PCR, and Western blot assays to further confirm that hypermethylation of the Ascl2 promoter, and elevated Ascl2 expression in CRC cells was partly due to the decreased expression of TET2. Furthermore, BCLAF1 was identified as a TET2 interactor in CRC cells by LC-MS/MS, coimmunoprecipitation, immunofluorescence colocalization, and proximity ligation assays. Subsequently, we found the TET2-BCLAF1 complex bound to multiple elements around CCGG sites at the Ascl2 promoter and further restrained its hypermethylation by inducing its hydroxymethylation using chromatin immunoprecipitation-qPCR and glucosylated hydroxymethyl-qPCR assays. Finally, we demonstrate that TET2-modulated Ascl2-targeted stem gene expression in CRC cells was independent of Wnt signaling. Taken together, our data suggest an additional option for inhibiting Ascl2 expression in CRC cells through TET2-BCLAF1-mediated promoter methylation, Ascl2-dependent self-renewal of CRC progenitor cells, and TET2-BCLAF1-related CRC progression.

BCLAF1-induced HIF-1α accumulation under normoxia enhances PD-L1 treatment resistances via BCLAF1-CUL3 complex.

Bcl-2-associated transcription factor-1 (BCLAF1), an apoptosis-regulating protein of paramount significance, orchestrates the progression of various malignancies. This study reveals increased BCLAF1 expression in hepatocellular carcinoma (HCC) patients, in whom elevated BCLAF1 levels are linked to escalated tumor grades and diminished survival rates. Moreover, novel BCLAF1 expression is particularly increased in HCC patients who were not sensitive to the combined treatment of atezolizumab and bevacizumab, but not in patients who had tumors that responded to the combined regimen. Notably, overexpression of BCLAF1 increases HCC cell proliferation in vitro and in vivo, while the conditioned medium derived from cells overexpressing BCLAF1 strikingly enhances the tube-formation capacity of human umbilical vein endothelial cells. Furthermore, compelling evidence demonstrates that BCLAF1 attenuates the expression of prolyl hydroxylase domain protein 2 (PHD2) and governs the stability of hypoxia-inducible factor-1α (HIF-1α) under normoxic conditions without exerting any influence on transcription, as determined by Western blot and RT‒qPCR analyses. Subsequently, employing coimmunoprecipitation and immunofluorescence, we validated the reciprocal interaction between BCLAF1 and Cullin 3 (CUL3), through which BCLAF1 actively upregulates the ubiquitination and degradation of PHD2. The Western blot and RT‒qPCR results suggests that programmed death ligand-1 (PD-L1) is one of the downstream responders to HIF-1α in HCC. Thus, we reveal the pivotal role of BCLAF1 in promoting PD-L1 transcription and, through binding to CUL3, in promoting the accumulation of HIF-1α under normoxic conditions, thereby facilitating the ubiquitination and degradation of PHD2.

Role of BCLAF-1 in PD-L1 stabilization in response to ionizing irradiation.

Programmed cell death ligand 1 (PD-L1) is a major immunosuppressive checkpoint protein expressed by tumor cells to subvert anticancer immunity. Recent studies have shown that ionizing radiation (IR) upregulates the expression of PD-L1 in tumor cells. However, whether an IR-induced DNA damage response (DDR) directly regulates PD-L1 expression and the functional significance of its upregulation are not fully understood. Here, we show that IR-induced upregulation of PD-L1 expression proceeds through both transcriptional and post-translational mechanisms. Upregulated PD-L1 was predominantly present on the cell membrane, resulting in T-cell apoptosis in a co-culture system. Using mass spectrometry, we identified PD-L1 interacting proteins and found that BCLAF1 (Bcl2 associated transcription factor 1) is an important regulator of PD-L1 in response to IR. BCLAF1 depletion decreased PD-L1 expression by promoting the ubiquitination of PD-L1. In addition, we show that CMTM6 is upregulated in response to IR and participates in BCLAF1-dependent PD-L1 upregulation. Finally, we demonstrated that the ATM/BCLAF1/PD-L1 axis regulated PD-L1 stabilization in response to IR. Together, our findings reveal a novel regulatory mechanism of PD-L1 expression in the DDR.

Bcl-2-associated transcription factor 1 Ser290 phosphorylation mediates DNA damage response and regulates radiosensitivity in gastric cancer.

BACKGROUND: DNA damage response plays critical roles in tumor pathogenesis and radiotherapy resistance. Protein phosphorylation is a critical mechanism in regulation of DNA damage response; however, the key mediators for radiosensitivity in gastric cancer still needs further exploration. METHODS: A quick label-free phosphoproteomics using high-resolution mass spectrometry and an open search approach was applied to paired tumor and adjacent tissues from five patients with gastric cancer. The dysregulated phosphoproteins were identified and their associated-pathways analyzed using Gene Set Enrichment Analysis (GSEA). The mostly regulated phosphoproteins and their potential functions were validated by the specific antibodies against the phosphorylation sites. Specific protein phosphorylation was further analyzed by functional and clinical approaches. RESULTS: 832 gastric cancer-associated unique phosphorylated sites were identified, among which 25 were up- and 52 down-regulated. Markedly, the dysregulated phosphoproteins were primarily enriched in DNA-damage-response-associated pathways. Particularly, the phosphorylation of Bcl-2-associated transcription factor 1 (BCLAF1) at Ser290 was significantly upregulated in tumor. The upregulation of BCLAF1 Ser290 phosphorylation (pBCLAF1 (Ser290)) in tumor was confirmed by tissue microarray studies and further indicated in association with poor prognosis of gastric cancer patients. Eliminating the phosphorylation of BCLAF1 at Ser290 suppressed gastric cancer (GC) cell proliferation. Upregulation of pBCLAF1 (Ser290) was found in association with irradiation-induced γ-H2AX expression in the nucleus, leading to an increased DNA damage repair response, and a marked inhibition of irradiation-induced cancer cell apoptosis. CONCLUSIONS: The phosphorylation of BCLAF1 at Ser290 is involved in the regulation of DNA damage response, indicating an important target for the resistance of radiotherapy.

Platelet-derived microparticles promote endothelial cell proliferation in hypertension via miR-142-3p.

Endothelial cells (ECs) are located at the interface between flowing blood and the vessel wall, and abnormal EC proliferation induced by pathologic environments plays an important role in vascular remodeling in hypertensive conditions. Exchanges of information between blood components and ECs are important for EC function. Hence, the present study sought to determine how platelets induce EC dysfunction under hypertensive conditions. EC proliferation was increased in renal hypertensive rats established by abdominal aortic coarctation compared with control rats and that elevated thrombin in plasma promoted platelet activation, which may induce the release of platelet-derived microparticles (PMPs). MicroRNA (MiR) array and qPCR revealed a higher level of miR-142-3p in platelets and PMPs. In vitro, PMPs delivered miR-142-3p into ECs and enhanced their proliferation via Bcl-2-associated transcription factor (BCLAF)1 and its downstream genes. These results indicate that PMPs deliver miR-142-3p from activated platelets into ECs and that miR-142-3p may play important roles in EC dysfunction in hypertensive conditions and may be a novel therapeutic target for maintaining EC homeostasis in hypertension.-Bao, H., Chen, Y.-X., Huang, K., Zhuang, F., Bao, M., Han, Y., Chen, X.-H., Shi, Q., Yao, Q.-P., Qi, Y.-X. Platelet-derived microparticles promote endothelial cell proliferation in hypertension via miR-142-3p.

B-cell lymphoma-2-associated transcription factor 1 is overexpressed and contributes to sorafenib resistance in hepatocellular carcinoma.

AIM: B-cell lymphoma-2-associated transcription factor 1 (BCLAF1) is involved in various biological processes including tumorigenesis, but its function and expression in hepatocellular carcinoma (HCC) is little known, and its clinical value in HCC has not yet been defined. METHODS: The protein level of BCLAF1 in HCC specimens and paired adjacent normal tissues was examined by immunohistochemical staining. The effects of BCLAF1 on autophagy in HCC cells were detected by confocal microscopy, transmission electron microscopy, and western blot analysis. Cell proliferation and tumorigenicity assays were carried out in vitro and in vivo. Flow cytometry assay was used to determine the apoptosis level of HCC cells. The correlation of BCLAF1 and sorafenib resistance in HCC was analyzed by the Kaplan-Meier survival method. RESULTS: High expression of BCLAF1 was found in HCC tissues compared with adjacent normal tissues, and higher BCLAF1 expression was correlated with higher tumor-node-metastasis stage, worse differentiation, and worse prognosis of HCC patients. BCLAF1 could induce autophagy in HCC cells in response to starvation and BCLAF1-mediated autophagy could enhance cell proliferation and impede cell apoptosis under stress conditions. Animal experiments indicated that BCLAF1 promoted tumorigenicity of HCC cells in vivo. More importantly, high expression of BCLAF1 might contribute to sorafenib resistance in HCC patients. CONCLUSIONS: BCLAF1 is a potential oncogene in HCC by inducing autophagy to maintain tumor cell growth in response to stress conditions, and it could serve as a potential biomarker for predicting the prognosis of HCC patients and screening patients who are suitable for sorafenib therapy.

Role of the DNA Damage Response in Human Papillomavirus RNA Splicing and Polyadenylation.

Human papillomaviruses (HPVs) have evolved to use the DNA repair machinery to replicate its DNA genome in differentiated cells. HPV activates the DNA damage response (DDR) in infected cells. Cellular DDR factors are recruited to the HPV DNA genome and position the cellular DNA polymerase on the HPV DNA and progeny genomes are synthesized. Following HPV DNA replication, HPV late gene expression is activated. Recent research has shown that the DDR factors also interact with RNA binding proteins and affects RNA processing. DDR factors activated by DNA damage and that associate with HPV DNA can recruit splicing factors and RNA binding proteins to the HPV DNA and induce HPV late gene expression. This induction is the result of altered alternative polyadenylation and splicing of HPV messenger RNA (mRNA). HPV uses the DDR machinery to replicate its DNA genome and to activate HPV late gene expression at the level of RNA processing.

Upregulated SMYD3 promotes bladder cancer progression by targeting BCLAF1 and activating autophagy.

The recent discovery of a large number of histone methyltransferases reveals important roles of these enzymes in regulating tumor development and progression. SMYD3, a histone methyltransferase, is associated with poor prognosis of patients with prostate and gastric cancer. In the study, we attempted to investigate its putative oncogenic role on bladder cancer. Here, we report that SMYD3 frequently amplified in bladder cancer is correlated with bladder cancer progression and poor prognosis. Overexpression of SMYD3 promotes bladder cancer cell proliferation and invasion, whereas SMYD3 knockdown inhibits cancer cell growth and invasion. Mechanically, SMYD3 positively regulates the expression of BCL2-associated transcription factor 1 (BCLAF1). SMYD3 physically interacts with the promoter of BCLAF1 and upregulates its expression by accumulating di- and trimethylation of H3K4 at the BCLAF1 locus. We further show that SMYD3 overexpression in bladder cancer cells promotes autophagy activation, whereas BCLAF1 depletion inhibits SMYD3-induced autophagy. Finally, we demonstrate that SMYD3 promotes bladder cancer progression, at least in part by increasing BCLAF1 expression and activating autophagy. Our results establish a function for SMYD3 in autophagy activation and bladder cancer progression and suggest its candidacy as a new prognostic biomarker and target for clinical management of bladder cancer.

Involvement of Bcl-2-associated transcription factor 1 in the differentiation of early-born retinal cells.

Retinal progenitor proliferation and differentiation are tightly controlled by extrinsic cues and distinctive combinations of transcription factors leading to the generation of retinal cell type diversity. In this context, we have characterized Bcl-2-associated transcription factor (Bclaf1) during rodent retinogenesis. Bclaf1 expression is restricted to early-born cell types, such as ganglion, amacrine, and horizontal cells. Analysis of developing retinas in Bclaf1-deficient mice revealed a reduction in the numbers of retinal ganglion cells, amacrine cells and horizontal cells and an increase in the numbers of cone photoreceptor precursors. Silencing of Bclaf1expression by in vitro electroporation of shRNA in embryonic retina confirmed that Bclaf1 serves to promote amacrine and horizontal cell differentiation. Misexpression of Bclaf1 in late retinal progenitors was not sufficient to directly induce the generation of amacrine and horizontal cells. Domain deletion analysis indicated that the N-terminal domain of Bclaf1 containing an arginine-serine-rich and a bZip domain is required for its effects on retinal cell differentiation. In addition, analysis revealed that Bclaf1 function occurs independently of its interaction with endogenous Bcl-2-related proteins. Altogether, our data demonstrates that Bclaf1expression in postmitotic early-born cells facilitates the differentiation of early retinal precursors into retinal ganglion cells, amacrine cells, and horizontal cells rather than into cone photoreceptors.

Identification and classification of glioma subtypes based on RNA-binding proteins.

BACKGROUND: Glioma is a common and aggressive primary malignant cancer known for its high morbidity, mortality, and recurrence rates. Despite this, treatment options for glioma are currently restricted. The dysregulation of RBPs has been linked to the advancement of several types of cancer, but their precise role in glioma evolution is still not fully understood. This study sought to investigate how RBPs may impact the development and prognosis of glioma, with potential implications for prognosis and therapy. METHODS: RNA-seq profiles of glioma and corresponding clinical data from the CGGA database were initially collected for analysis. Unsupervised clustering was utilized to identify crucial tumor subtypes in glioma development. Subsequent time-series analysis and MS model were employed to track the progression of these identified subtypes. RBPs playing a significant role in glioma progression were then pinpointed using WGCNA and Lasso Cox regression models. Functional analysis of these key RBP-related genes was conducted through GSEA. Additionally, the CIBERSORT algorithm was utilized to estimate immune infiltrating cells, while the STRING database was consulted to uncover potential mechanisms of the identified biomarkers. RESULTS: Six tumor subgroups were identified and found to be highly homogeneous within each subgroup. The progression stages of these tumor subgroups were determined using time-series analysis and a MS model. Through WGCNA, Lasso Cox, and multivariate Cox regression analysis, it was confirmed that BCLAF1 is correlated with survival in glioma patients and is closely linked to glioma progression. Functional annotation suggests that BCLAF1 may impact glioma progression by influencing RNA splicing, which in turn affects the cell cycle, Wnt signaling pathway, and other cancer development pathways. CONCLUSIONS: The study initially identified six subtypes of glioma progression and assessed their malignancy ranking. Furthermore, it was determined that BCLAF1 could serve as an RBP-related prognostic marker, offering significant implications for the clinical diagnosis and personalized treatment of glioma.

BCLAF1 drives esophageal squamous cell carcinoma progression through regulation of YTHDF2-dependent SIX1 mRNA degradation.

Esophageal cancer ranks among the most prevalent malignant tumors, and esophageal squamous cell carcinoma (ESCC) constitutes its predominant histological form. Despite its impact, a thorough insight into the molecular intricacies of ESCC's development is still incomplete, which hampers the advancement of targeted molecular diagnostics and treatments. Recently, B-cell lymphoma-2-associated transcription factor 1 (BCLAF1) has come under investigation for its potential involvement in tumor biology, yet its specific role and mechanism in ESCC remain unclear. In this study, we observed a marked increase in BCLAF1 expression in ESCC tissues, correlating with advanced tumor stages and inferior patient outcomes. Our comprehensive in vitro and in vivo studies show that BCLAF1 augments glycolytic activity and the proliferation, invasion, and spread of ESCC cells. By employing mass spectrometry, we identified YTHDF2 as a key protein interacting with BCLAF1 in ESCC, with further validation provided by colocalization, co-immunoprecipitation, and GST pull-down assay. Further investigations involving MeRIP-seq and RIP-seq, alongside transcriptomic analysis, highlighted SIX1 mRNA as a molecule significantly upregulated and modified by N6-methyladenosine (m6A) in BCLAF1 overexpressing cells. BCLAF1 was found to reduce the tumor-suppressive activities of YTHDF2, and its effects on promoting glycolysis and cancer progression were shown to hinge on SIX1 expression. This research establishes that BCLAF1 fosters glycolysis and tumor progression in ESCC through the YTHDF2-SIX1 pathway in an m6A-specific manner, suggesting a potential target for future therapeutic intervention.

CircZFR promotes colorectal cancer progression via stabilizing BCLAF1 and regulating the miR-3127-5p/RTKN2 axis.

Aberrant expression of circular RNAs (circRNAs) is frequently linked to colorectal cancer (CRC). Here, we identified circZFR as a promising biomarker for CRC diagnosis and prognosis. CircZFR was upregulated in CRC tissues and serum exosomes and its level was linked to cancer incidence, advanced-stages, and metastasis. In both in vitro and in vivo settings, circZFR promoted the growth and spread while suppressing apoptosis of CRC. Exosomes with circZFR overexpression promoted the proliferation and migration of cocultured CRC cells. Mechanistically, epithelial splicing regulatory protein 1 (ESRP1) in CRC cells may enhance the production of circZFR. BCL2-associated transcription factor 1 (BCLAF1) bound to circZFR, which prevented its ubiquitinated degradation. Additionally, circZFR sponged miR-3127-5p to boost rhotekin 2 (RTKN2) expression. Our TCP1-CD-QDs nanocarrier was able to carry and deliver circZFR siRNA (si-circZFR) to the vasculature of CRC tissues and cells, which inhibited the growth of tumors in patient-derived xenograft (PDX) models. Taken together, our results show that circZFR is an oncogenic circRNA, which promotes the development and spread of CRC in a BCLAF1 and miR-3127-5p-dependent manner. CircZFR is a possible serum biopsy marker for the diagnosis and a desirable target for further treatment of CRC.

Phosphoproteomic and proteomic profiling in post-infarction chronic heart failure.

Background: Post-infarction chronic heart failure is the most common type of heart failure. Patients with chronic heart failure show elevated morbidity and mortality with limited evidence-based therapies. Phosphoproteomic and proteomic analysis can provide insights regarding molecular mechanisms underlying post-infarction chronic heart failure and explore new therapeutic approaches. Methods and results: Global quantitative phosphoproteomic and proteomic analysis of left ventricular tissues from post-infarction chronic heart failure rats were performed. A total of 33 differentially expressed phosphorylated proteins (DPPs) and 129 differentially expressed proteins were identified. Bioinformatic analysis indicated that DPPs were enriched mostly in nucleocytoplasmic transport and mRNA surveillance pathway. Bclaf1 Ser658 was identified after construction of Protein-Protein Interaction Network and intersection with Thanatos Apoptosis Database. Predicted Upstream Kinases of DPPs based on kinase-substrate enrichment analysis (KSEA) app showed 13 kinases enhanced in heart failure. Proteomic analysis showed marked changes in protein expression related to cardiac contractility and metabolism. Conclusion: The present study marked phosphoproteomics and proteomics changes in post-infarction chronic heart failure. Bclaf1 Ser658 might play a critical role in apoptosis in heart failure. PRKAA1, PRKACA, and PAK1 might serve as potential therapeutic targets for post-infarction chronic heart failure.

Function of BCLAF1 in human disease.

Originally identified as a regulator of apoptosis and transcription, B-cell lymphoma-2-associated transcription factor 1 (BCLAF1) has since been shown to be associated with a multitude of biological processes, such as DNA damage response, splicing and processing of pre-mRNA, T-cell activation, lung development, muscle cell proliferation and differentiation, autophagy, ischemia-reperfusion injury, and viral infection. In recent years, an increasing amount of evidence has shown that BCLAF1 acts as either a tumor promoter or tumor suppressor in tumorigenesis depending on the cellular context and the type of cancer. Even in the same tumor type, BCLAF1 may have opposite effects. In the present review, the subcellular localization, structural features, mutations within BCLAF1 will be described, then the regulation of BCLAF1 and its downstream targets will be analyzed. Furthermore, the different roles and possible mechanisms of BCLAF1 in tumorigenesis will also be highlighted and discussed. Finally, BCLAF1 may be considered as a potential target for cancer therapy in the future.

BCLAF1, a functional partner of BACH1, participates in DNA damage response.

BACH1 (Brca1-Associated C-terminal Helicase) is an important DNA damage response factor, which is involved in DNA damage repair and maintenance of genomic stability. In this study, by using tandem protein affinity purification, we have identified BCLAF1 as a novel functional partner of BACH1. BCLAF1 constitutively interacts with BACH1 regardless of DNA damage. However, in response to DNA damage, along with BACH1, BCLAF1 is recruited to the DNA damage sites and the recruitment of BCLAF1 was regulated by BACH1 and BRCA1. Interestingly, BCLAF1 deficient cells are deficient for DSB-initiated HR, but RAD51 foci formation is intact following IR treatment. Taken together, these findings reveal that BCLAF1 is a functional binding partner of BACH1 playing a key role in DNA damage response.

Curcumin induces mitochondrial apoptosis in human hepatoma cells through BCLAF1-mediated modulation of PI3K/AKT/GSK-3ß signaling.

Curcumin is a yellow pigment extracted from the rhizome of turmeric, a traditional Chinese medicine. Here, we tested the hypothesis that curcumin-mediated downregulation of BCLAF1 triggers mitochondrial apoptosis in hepatoma cells by inhibiting PI3K/AKT/GSK-3ß signaling. Treatment of the human hepatoma cell lines, HepG2 and SK-Hep-1, with various concentrations of curcumin revealed a time-dependent and concentration-dependent inhibition of cell proliferation, increased apoptosis, cell cycle arrest at the G0/G1 phase, reduced mitochondrial membrane potential, and reduced expression levels of PI3K, p-PI3K, AKT, p-AKT, GSK-3ß, and p-GSK-3ß. Additionally, curcumin suppressed the levels of apoptotic factors after treating the cells with LY294002, a PI3K inhibitor. Curcumin also suppressed the expression of BCLAF1. Treating stable BCLAF1 knockout HepG2 and SK-Hep-1 cells with curcumin further enhanced apoptosis and increased the number of cells in G0/G1 cell cycle arrest, while inhibiting the downregulation of PI3K/AKT/GSK-3ß pathway-related proteins. Treatment of a nude mouse xenograft model bearing HepG2 cells with curcumin inhibited tumor growth, disrupted the cellular structure of the tumor tissue, and suppressed the expression of BCLAF1 and PI3K/AKT/GSK-3ß proteins. In summary, our in vitro and in vivo analyses show that curcumin downregulates BCLAF1 expression, inhibits the activation of the PI3K/AKT/GSK-3ß pathway, and triggers mitochondrial apoptosis in HCC. These findings uncover a potential therapeutic strategy leveraging the antitumor effects of curcumin against HCC.