Expression and functional characterization of INPP4B in gallbladder cancer patients and gallbladder cancer cells

Background Inositol polyphosphate 4-phosphatase type II (INPP4B) is a negative regulator of the PI3K-Akt signalling pathway and plays a contradictory role in different types of cancers. However, the its biological role played by INPP4B in human gallbladder cancer (GBC) has not been elucidated. In this study, we investigated the expression, clinical significance and biological function of INPP4B in GBC patients and cell lines. Methods The INPP4B protein expression levels in gallbladder cancer tissues and normal gallbladder tissues were detected by immunohistochemistry, and the clinical significance of INPP4B was analysed. Knockdown and overexpression of INPP4B in GBC-SD and SGC-996 cells followed by cell proliferation, clonogenic, apoptosis detection, scratch wound-healing and transwell assays were used to identify INPP4B function in vitro. Results INPP4B was up-regulated in human GBC tissues compared with normal gallbladder tissues and was related to histopathological differentiation (p = 0.026). Here, we observed that INPP4B was highly expressed in high-moderately differentiated tumours compared with low-undifferentiated tumours (p = 0.022). Additionally, we found that INPP4B expression was not associated with overall survival of GBC patients (p = 0.071) and was not an independent prognostic factor. Furthermore, when we stratified the relationship between INPP4B expression and the prognosis of GBC based on histopathological differentiation, we found that INPP4B played a contradictory role in GBC progression depending on the degree of differentiation. In addition, INPP4B knockdown inhibited the proliferation, colony formation, migration and invasion in GBC cells, while INPP4B overexpression had the opposite effects in vitro, which indicates its role as an oncoprotein. Conclusions These findings suggested that INPP4B may play a dual role in the prognosis of GBC depending on the degree of differentiation and that INPP4B might act as an oncogene in gallbladder cancer cells.

A pro-endocrine pancreatic transcriptional program established during development is retained in human gallbladder epithelial cells

ObjectivePancreatic islet β-cells are factories for insulin production; however ectopic expression of insulin is also well recognized. The gallbladder is a next-door neighbour to the developing pancreas. Here, we wanted to understand if gallbladders contain functional insulin-producing cells.DesignWe compared developing and adult mouse as well as human gallbladder epithelial cells and islets using immunohistochemistry, flow cytometry, ELISAs, RNA-sequencing, real-time PCR, chromatin immunoprecipitation and functional studies.ResultsWe demonstrate that the epithelial lining of developing, as well as adult mouse and human gallbladders naturally contain interspersed cells that retain the capacity to actively transcribe, translate, package, and release insulin. We show for the first time that human gallbladders also contain functional insulin-secreting cells with the potential to naturally respond to glucose in vitro and in situ. Notably, in a NOD mouse model of type 1 diabetes, we observed that insulin-producing cells in the gallbladder are not targeted by autoimmune cells. Conclusion: In summary, our biochemical, transcriptomic, and functional data in human gallbladder epithelial cells collectively demonstrate their potential for insulin-production under pathophysiological conditions, and open newer areas for type 1 diabetes research and therapy.Significance of the studyWhat is already known about this subject?Developing pancreas and gallbladder are next-door neighbours and share similar developmental pathways.Human Gallbladder-derived progenitor cells were shown to differentiate into insulin-producing cells.What are the new findings?Gallbladder epithelium contains interspersed cells that can transcribe, translate, package and secrete insulin.Insulin-producing cells in the gallbladder are not destroyed by immune cells in an animal model of type 1 diabetes (T1D).Our studies demonstrating the absence of insulin splice variants in human gallbladder cells, and higher splice forms in human islets, suggest a potential mechanism (via defective ribosomal products) in escaping islet autoimmunity.How might it impact clinical practice?Deciphering mechanisms of protection of insulin-producing cells from immune cells in the gallbladder could help in developing strategies to prevent islet autoimmunity in T1D.

Isorhamnetin Inhibits Human Gallbladder Cancer Cell Proliferation and Metastasis via PI3K/AKT Signaling Pathway Inactivation

Gallbladder cancer (GBC) is the most common biliary tract tumor with a poor prognosis. Isorhamnetin is a flavonoid compound extracted from Hippophae rhamnoides L. and has several pharmacological effects including anti-inflammatory and anti-cancer properties. We treated GBC-SD and NOZ of GBC cell lines with different isorhamnetin concentrations in vitro. A cell counting kit-8 (CCK-8) assay, transwell assay, Hoechst 33342 stain assay, flow cytometric analysis, and a colony-forming assay were performed to investigate the effect of isorhamnetin on the proliferation, apoptosis, metastasis, and cycle arrest of GBC cells. A western blotting assay was conducted to explore the related protein expression level of GBC cells. A mice xenograft model and immunohistochemistry staining were employed to assess the effect of isorhamnetin in vivo. Isorhamnetin was found to suppress cell proliferation and metastasis, and trigger apoptosis and arrest the G2/M phase in GBC cells via the inactivation of the PI3K/AKT signaling cascade. Our findings are of clinical significance in providing a novel treatment approach for GBC.

Expression and Functional Identification of INPP4B in Gallbladder Cancer Patients and Gallbladder Cancer Cells

Purpose: Inositol polyphosphate 4-phosphatase type II (INPP4B) is a negative regulator of PI3K-Akt signaling pathway and plays a contradictory role in different types of cancers. However, its biological role in human gallbladder cancer (GBC) remain unclear. Here we aimed to investigate the expression, clinical significance and biological function of INPP4B in GBC clinical dates and GBC cell lines. Methods: The INPP4B protein expression levels in gallbladder cancer tissues and normal gallbladder tissues were detected by immunohistochemistry, and the clinical significance of INPP4B was analyzed. Knockdown and overexpression of INPP4B on GBC-SD and SGC-996 cells were used to identify INPP4B function in vitro, using cell proliferation assay, clonogenic assay, apoptosis detection, cratch wound-healing assay and transwell assay.Results: INPP4B was up-regulated in human GBC tissues compared with normal gallbladder tissues, and was related to histopathological differentiation. Here, we observed that INPP4B was highly expressed in high-moderate differentiated compared to low-undifferentiated. Additionally, we found that INPP4B expression was not associated with overall survival in GBC patients and was not an independent prognostic factor. Furthermore, when we stratified the relationship between INPP4B expression and prognosis of GBC from histopathological differentiation, we found that INPP4B played a contradictory role in GBC progression at different degrees of differentiation. In addition, INPP4B knockdown inhibited tumorigenicity in vitro, and INPP4B overexpression induced tumorigenicity in vitro, which may play a role as an oncoprotein.Conclusions: These findings implicated that INPP4B may play a dual role in the prognosis of GBC with different degrees of differentiation, and might act as an oncogene in gallbladder cancer cells.

Genotoxic Effect of Salmonella Paratyphi A Infection on Human Primary Gallbladder Cells

ABSTRACT Carcinoma of the gallbladder (GBC) is the most frequent tumor of the biliary tract. Despite epidemiological studies showing a correlation between chronic infection with Salmonella enterica Typhi/Paratyphi A and GBC, the underlying molecular mechanisms of this fatal connection are still uncertain. The murine serovar Salmonella Typhimurium has been shown to promote transformation of genetically predisposed cells by driving mitogenic signaling. However, insights from this strain remain limited as it lacks the typhoid toxin produced by the human serovars Typhi and Paratyphi A. In particular, the CdtB subunit of the typhoid toxin directly induces DNA breaks in host cells, likely promoting transformation. To assess the underlying principles of transformation, we used gallbladder organoids as an infection model for Salmonella Paratyphi A. In this model, bacteria can invade epithelial cells, and we observed host cell DNA damage. The induction of DNA double-strand breaks after infection depended on the typhoid toxin CdtB subunit and extended to neighboring, non-infected cells. By cultivating the organoid derived cells into polarized monolayers in air-liquid interphase, we could extend the duration of the infection, and we observed an initial arrest of the cell cycle that does not depend on the typhoid toxin. Non-infected intoxicated cells instead continued to proliferate despite the DNA damage. Our study highlights the importance of the typhoid toxin in causing genomic instability and corroborates the epidemiological link between Salmonella infection and GBC. IMPORTANCE Bacterial infections are increasingly being recognized as risk factors for the development of adenocarcinomas. The strong epidemiological evidence linking Helicobacter pylori infection to stomach cancer has paved the way to the demonstration that bacterial infections cause DNA damage in the host cells, initiating transformation. In this regard, the role of bacterial genotoxins has become more relevant. Salmonella enterica serovars Typhi and Paratyphi A have been clinically associated with gallbladder cancer. By harnessing the stem cell potential of cells from healthy human gallbladder explant, we regenerated and propagated the epithelium of this organ in vitro and used these cultures to model S. Paratyphi A infection. This study demonstrates the importance of the typhoid toxin, encoded only by these specific serovars, in causing genomic instability in healthy gallbladder cells, posing intoxicated cells at risk of malignant transformation.