Bif-1 and Bax expression in cutaneous Merkel cell carcinoma

Bif‑1 inhibits activation of inflammasome through autophagy regulatory mechanism

Inflammasome activation is a crucial mechanism in inflammatory responses. Bax‑interacting factor 1 (Bif‑1) is required for the normal formation of autophagosomes, but its ability to exert an inflammatory regulatory effect remains unclear. The aim of the present study was to explore the role of Bif‑1 in inflammation, possibly mediated through autophagy regulation. Using a lipopolysaccharide (LPS)/adenosine triphosphate (ATP)‑induced inflammatory model in J774A.1 cells, the effect of Bif‑1 on inflammasome activation and the underlying mechanisms involving autophagy regulation were investigated. Elevated levels of NLR family pyrin domain containing protein 3 inflammasome and interleukin‑1β (IL‑1β) proteins were observed in J774A.1 cells after LPS/ATP induction. Furthermore, Bif‑1 and autophagy activity were significantly upregulated in inflammatory cells. Inhibition of autophagy resulted in inflammasome activation. Silencing Bif‑1 expression significantly upregulated IL‑1β levels and inhibited autophagy activity, suggesting a potential anti‑inflammatory role of Bif‑1 mediated by autophagy. Additionally, inhibition of the nuclear factor‑κB (NF‑κB) signaling pathway downregulated Bif‑1 and inhibited autophagy activity, highlighting the importance of NF‑κB in the regulation of Bif‑1 and autophagy. In summary, the current study revealed that Bif‑1 is a critical anti‑inflammatory factor against inflammasome activation mediated by a mechanism of autophagy regulation, indicating its potential as a therapeutic target for inflammatory regulation.

BIF-1 inhibits both mitochondrial and glycolytic ATP production: its downregulation promotes melanoma growth

Endophilin B1, also known as BAX-interacting protein 1 (BIF-1), is part of the endophilin B protein family, and is a multifunctional protein involved in the regulation of apoptosis, autophagy, and mitochondrial morphology. The role of BIF-1 in cancer is controversial since previous reports indicated to both tumor-promoting and tumor-suppressive roles, perhaps depending on the cancer cell type. In the present study, we report that BIF-1 is significantly downregulated in both primary and metastatic melanomas, and that patients with high levels of BIF-1 expression exhibited a better overall survival. Depleting BIF-1 using CRISPR/Cas9 technology in melanoma cells resulted in higher proliferation rates both in vitro and in vivo, a finding that was associated with increased ATP production, metabolic acidification, and mitochondrial respiration. We also observed mitochondrial hyperpolarization, but no increase in the mitochondrial content of BIF-1-knockout melanoma cells. In contrast, such knockout melanoma cells were equally sensitive to anticancer drug- or UV irradiation-induced cell death, and exhibited similar autophagic activities as compared with control cells. Taken together, it appears that downregulation of BIF-1 contributes to tumorigenesis in cutaneous melanoma by upregulating mitochondrial respiration and metabolism, independent of its effect on apoptosis and autophagy.

The Genetic and Molecular Determinants of Juvenile Nasopharyngeal Angiofibroma: A Systematic Review

Objective:

Juvenile nasopharyngeal angiofibroma (JNA) is a rare vascular tumor of unknown etiology. Studies investigating the molecular and genetic determinants of JNA are limited by small sample size and inconsistent approaches. The purpose of this study is to examine all eligible JNA studies in aggregate, applying qualitative analysis to highlight areas of particular relevance, including potential targets for therapeutic intervention.

Methods:

The PubMed, MEDLINE, Embase, Web of Science, Cochrane, and CINAHL databases were screened with inclusion and exclusion criteria applied to all citations. Manuscripts investigating the genetic determinants, histopathogenesis, and heritability of juvenile nasopharyngeal angiofibroma were included. Non-English studies, case reports, and articles focusing on clinical management without original data were excluded. Full text articles were obtained. A qualitative synthesis of data was performed.

Results:

A total of 59 articles met criteria for inclusion. These were divided into 6 categories based on the primary topic or target discussed, (1) steroid hormone receptors, (2) chromosomal abnormalities, (3) growth factors, (4) genetic targets, (5) molecular targets, (6) Wnt cell signaling, and (7) studies that overlapped multiple of the aforementioned categories. Although relatively low n values prevent definitive conclusions to be drawn, a predominance of certain molecular targets such as vascular endothelial growth factor (VEGF) and Wnt/β-catenin pathway intermediaries is apparent.

Conclusions:

Although the etiology of JNA remains elusive, contemporary molecular genetic investigation holds promise for risk stratification and could form the basis of a modernized staging system. A multicenter clinical registry and linked tissue bank would further promote the search for JNA specific biomarkers.

Bax-interacting factor-1 inhibits cell proliferation and promotes apoptosis in prostate cancer cells

Prostate cancer (PCa) is one of the most common malignant tumors and the second leading cause of cancer-related death among males. Bax-interacting factor-1 (Bif-1) is a member of Endophilin family, which binds to and activates the BAX protein in response to the apoptosis signaling pathway. Loss of Bif-1 may suppress the intrinsic pathway of apoptosis and promote tumorigenesis, but there is also converse evidence that Bif-1 could in part be responsible for the tumorigenesis and the role of Bif-1 in PCa development is not clear. In the present study, we aimed to understand the relationships between Bif-1 expression and PCa development. The mRNA and protein expression levels of Bif-1 in PCa cell lines, benign prostatic hyperplasia (BPH) (n=100) and PCa tissues (n=100, including low Gleason-scored PCa n=43 and high Gleason-scored PCa n=57) were detected and the effects of Bif-1 overexpression on the apoptosis, proliferation and migration in LNCaP cells were explored. Bif-1 mRNA levels of PCa cell lines were analyzed by real-time PCR and the protein levels were detected by western blotting. Bif-1 expression in BPH and PCa samples was detected by immunohistochemistry. To build Bif-1 overexpression PCa cells, Bif-1 gene was transfected into LNCaP cells by pcDNA3.1(+)‑Bif-1 vector. Cell apoptosis was detected by flow cytometric analysis, cell proliferation measured by 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide (MTT) assay and cell migration was analyzed by wound‑healing assay. The results proved that Bif-1 is downregulated in both PCa cell lines (P<0.01) and clinical samples (P<0.05), and Bif-1 expression is suppressed with the cancer progression (BPH vs. PCa P<0.01, and low Gleason-scored PCa vs. high Gleason-scored PCa P<0.05). Overexpression of Bif-1 could significantly inhibit cell proliferation (P<0.05) and enhancing PCa cell apoptosis (P<0.05), but it did not affect the migration ability (P>0.05). Our findings give strong evidence that Bif-1 is involved in PCa tumorigenesis and acts as a suppressor in PCa progression, and may have significance in understanding the process of PCa development.

Bif-1 promotes tumor cell migration and metastasis via Cdc42 expression and activity

Tumor metastasis is the process by which tumor cells disseminate from tumors and enter nearby and distant microenvironments for new colonization. Bif-1 (BAX-interacting factor 1), which has a BAR domain and an SH3 domain, has been reported to be involved in cell growth, apoptosis and autophagy. However, the influence of Bif-1 on metastasis has been less studied. To understand the role of Bif-1 in metastasis, we studied the expression levels of Bif-1 in human HCC specimens using immunohistochemistry, a tissue microarray and quantitative PCR. The function of Bif-1 was assessed in migration and translocation assays and the pulmonary metastatic animal model. The relationship between Bif-1 and the Rho family was determined using immunoblot analyses and chromatin immunoprecipitation. The results showed that the expression of Bif-1 was higher in hepatocellular carcinoma (HCC) than matched adjacent non-tumor liver tissues. Increased Bif-1 expression was associated with tumor size and the intercellular spread and metastasis of HCC. Analysis of the relationship between Bif-1 expression and patients' clinical characteristics revealed that patients with higher levels of Bif-1 had shorter disease-free and overall survival rates. Knockdown of Bif-1 with RNAi suppressed the migration of HCC cells and pulmonary metastasis and decreased the expression of Cdc42, a member of the Rho family. Bif-1 localized to the cytosol and nucleus and interacted with the promoter transcription region of Cdc42, which may regulate Cdc42 expression. Our results demonstrate a novel role of Bif-1 in HCC, in which Bif-1 promotes cell metastasis by regulating Cdc42 expression and activity.

Bif-1 is overexpressed in hepatocellular carcinoma and correlates with shortened patient survival

Bax-interacting factor-1 (Bif-1) interacts with Beclin1 [the mammalian ortholog of yeast autophagy-related gene 6 (Atg6)] and affects the formation of autophagosomes during autophagy. The aim of this study was to explore Bif-1 expression and its prognostic significance in comparison with various clinicopathological predictors of survival. Bif-1 protein expression was determined by immunohistochemistry in 206 hepatocellular carcinomas. Cytoplasmic immunoreactivity was scored semi-quantitatively. The results were analyzed in correlation with various clinicopathological characteristics, including patient survival. The Chi-square test and Kaplan-Meier survival analysis were applied. The expression of Bif-1 was significantly higher in the hepatocellular cancers than in the adjacent matched non-tumor tissues (51.5 vs. 33.0%, P<0.01). Increased expression of Bif-1 in hepatocellular carcinomas was significantly correlated with a low grade of differentiation and a shortened overall survival (P<0.05). No significant differences were found between the expression of Bif-1 and age, gender, tumor size, damage of capsule, expression of hepatitis B surface antigen (HBs-Ag) and portal venous invasion. Our data demonstrated that Bif-1 is frequently expressed in hepatocellular carcinoma. Overexpression of Bif-1 is a new independent prognostic marker, which is associated with poor differentiation as well as shortened overall survival.