Mutant p53 driven-LINC00857, a protein scaffold between FOXM1 and deubiquitinase OTUB1, promotes the metastasis of pancreatic cancer.

Tumour metastasis is the major adverse factor for recurrence and death in pancreatic cancer (PC) patients. P53 mutations are considered to be the second most common type of mutation in PC and significantly promote PC metastasis. However, the molecular mechanisms underlying the effects of p53 mutations, especially the regulatory relationship of the protein with long noncoding RNAs (lncRNAs), remain unclear. In the present study, we demonstrated that the lncRNA LINC00857 exhibits a significantly elevated level in PC and that it is associated with poor prognosis; furthermore, TCGA data showed that LINC00857 expression was significantly upregulated in the mutant p53 group compared with the wild-type p53 group. Gain- and loss-of-function experiments showed that LINC00857 promotes the metastasis of PC cells. We further found that LINC00857 upregulates FOXM1 protein expression and thus accelerates metastasis in vitro and in vivo. Mechanistically, LINC00857 bound simultaneously to FOXM1 and to the deubiquitinase OTUB1, thereby serving as a protein scaffold and enhancing the interaction between FOXM1 and OTUB1, which inhibits FOXM1 degradation through the ubiquitin-proteasome pathway. Interestingly, we found that mutant p53 promotes LINC00857 transcription by binding to its promoter region. Finally, atorvastatin, a commonly prescribe lipid-lowering drug, appeared to inhibit PC metastasis by inhibiting the mutant p53-LINC00857 axis. Taken together, our results provide new insights into the biology driving PC metastasis and indicate that the mutant p53-LINC00857 axis might represent a novel therapeutic target for PC metastasis.

Huaier suppresses pancreatic cancer progression via activating cell autophagy induced ferroptosis.

Purpose: The anti-tumour effect of Huaier has been demonstrated in a variety of tumours. Ferroptosis is a newly identified type of programmed cell death accompanied by the accumulation of reactive oxygen species (ROS) and iron in cells and plays a key role in the therapeutic process against malignant tumours. We aimed to explore the potential therapeutic role of Huaier in pancreatic cancer and uncover the relationship between Huaier and ferroptosis. Methods: CCK8 and colony formation assays were used to determine the proliferation of pancreatic cancer cells (PCs). The levels of cellular ROS were analysed by a fluorescence probe, and the accumulation of cellular iron was showed by Prussian blue staining. The autophagosomes and mitochondrial morphology were characterised by transmission electron microscopy (TEM). The levels of intracellular glutathione (GSH) and lipid peroxidation were measured by the corresponding kits. Results: The growth inhibitory effect of Huaier on PCs was concentration- and time-dependent, but this effect was significantly attenuated by ferroptosis inhibitors. In addition, Huaier effectively inhibited the GSH-GPX4 antioxidation system and resulted in the massive accumulation of ROS in PCs As shown by TEM, Huaier-treated PCs exhibited a decrease in mitochondrial cristae and a smaller mitochondrion, accompanied by an increase in autophagosomes. Indeed, we found that autophagy can induce ferroptosis in PCs and that Huaier-induced ferroptosis can be suppressed by the autophagosome inhibitor, Wortmannin. Conclusion: Huaier can activate ferroptosis by inducing autophagy in PCs.

Mechanically activated ion channel Piezo1 contributes to melanoma malignant progression through AKT/mTOR signaling.

Melanoma is a highly aggressive cancer that can metastasize at early stage. The aim of this study is to clarify the role of Piezo1 and its potential mechanism in regulating the malignant phenotypes of melanoma. In the present study, we first showed that Piezo1 was abnormally expressed in melanoma, which accelerated the malignant progression by activating AKT/mTOR signaling. Firstly, we found that Piezo1 was upregulated in melanoma and associated with poor survival. Additionally, Piezo1 knockdown significantly weakened intracellular calcium signal and viability of melanoma cells. Furthermore, Piezo1 knockdown inhibited the transendothelial migration and invasion in vitro, as well as metastasis in vivo. Mechanistically, we found that Piezo1 activated AKT/mTOR signaling to maintain malignant phenotypes of melanoma. Therefore, Piezo1 acts as an oncogene in melanoma cells and provides a novel candidate for melanoma diagnosis and treatment.

Thiostrepton induces ferroptosis in pancreatic cancer cells through STAT3/GPX4 signalling.

Ferroptosis is a new form of regulated cell death that is mediated by intracellular iron and ester oxygenase, and glutathione-dependent lipid hydroperoxidase glutathione peroxidase 4 (GPX4) prevents ferroptosis by converting lipid hydroperoxides into nontoxic lipid alcohols. Although thiostrepton (TST) has been reported to exert antitumor effects, its role in pancreatic cancer and the underlying mechanisms remain unclear. In this study, we found that TST reduced the viability and clonogenesis of pancreatic cancer cell lines, along with intracellular iron overload, increasing reactive oxygen species (ROS) accumulation, malondialdehyde (MDA) overexpression, and glutathione peroxidase (GSH-PX) depletion. Mechanistically, chromatin immunoprecipitation (ChIP) and dual luciferase reporter gene assays were used to confirm that signal transducer and activator of transcription 3 (STAT3) binds to the GPX4 promoter region and promotes its transcription, whereas TST blocked GPX4 expression by regulating STAT3. Finally, in vivo experiments revealed that TST inhibited the growth of subcutaneously transplanted tumours and had considerable biosafety. In conclusion, our study identified the mechanism by which TST-induced ferroptosis in pancreatic cancer cells through STAT3/GPX4 signalling.

RASAL2 mediated the enhancement of YAP1/TIAM1 signaling promotes malignant phenotypes of pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a high incidence of metastasis and dismal prognosis. As a member of Gas-Gap gene, RASAL2 is involved in the hydrolysis of RAS-GTP to RAS-GDP and abnormal expression in human cancers. Here we firstly described the function of RASAL2 on PDAC to enrich the knowledge of RAS family.We interestingly observed that RASAL2 expression was upregulated in PDAC at both mRNA and protein levels, and high expression of RASAL2 predicted a poor prognosis in PDAC patients. Additionally, RASAL2 promoted malignant behaviors of PDAC in vitro and in vivo. To determine the mechanistic roles of RASAL2 signaling and its potential as a therapeutic target in PDAC, we clarified that RASAL2 could accumulate the TIAM1 expression in different level through inhibiting YAP1 phosphorylation, increased TIAM1 mRNA expression and suppressed ubiquitination of TIAM1 protein. In conclusion, RASAL2 enhances YAP1/TIAM1 signaling and promotes PDAC development and progression.

Autophagic Schwann cells promote perineural invasion mediated by the NGF/ATG7 paracrine pathway in pancreatic cancer.

BACKGROUND: Perineural invasion (PNI) and autophagy are two common features in the tumor microenvironment of pancreatic cancer (PanCa) and have a negative effect on prognosis. Potential mediator cells and the molecular mechanism underlying their relationships need to be fully elucidated. METHODS: To investigate the autophagy of Schwann cells (SCs) in PNI, we reproduced the microenvironment of PNI by collecting clinical PNI tissue, performing sciatic nerve injection of nude mice with cancer cells and establishing a Dorsal root ganglion (DRG) coculture system with cancer cell lines. Autophagy was detected by IHC, IF, transmission electron microscopy (TEM) and western blotting assays. Apoptosis was detected by IF, TEM and western blotting. NGF targeting molecular RO 08-2750(RO) and the autophagy inhibitor Chloroquine (CQ) were utilized to evaluate the effect on autophagy and apoptosis in SCs and PanCa cells in PNI samples. RESULTS: SC autophagy is activated in PNI by paracrine NGF from PanCa cells. Autophagy-activated Schwann cells promote PNI through a) enhanced migration and axon guidance toward PanCa cells and b) increased chemoattraction to PanCa cells. The NGF-targeting reagent RO and autophagy inhibitor CQ inhibited Schwann cell autophagic flux and induced Schwann cell apoptosis. Moreover, RO and CQ could induce PanCa cell apoptosis and showed good therapeutic effects in the PNI model. CONCLUSIONS: PanCa cells can induce autophagy in SCs through paracrine pathways such as the NGF/ATG7 pathway. Autophagic SCs exert a "nerve-repair like effect", induce a high level of autophagy of cancer cells, provide a "beacon" for the invasion of cancer cells to nerve fibers, and induce directional growth of cancer cells. Targeting NGF and autophagy for PNI treatment can block nerve infiltration and is expected to provide new directions and an experimental basis for the research and treatment of nerve infiltration in pancreatic cancer.

High­glucose microenvironment promotes perineural invasion of pancreatic cancer via activation of hypoxia inducible factor 1α.

Pancreatic cancer (PC) is one of the most lethal diseases, with a 5­year survival rate of <9%. Perineural invasion (PNI) is a common pathological hallmark of PC and is correlated with a poor prognosis in this disease. Hyperglycemia has been shown to promote the invasion and migration of PC cells; however, the effect of hyperglycemia on the PNI of PC and its underlying mechanism remains unclear. In the present study, Western blotting was utilized to detect the expression of hypoxia inducible factor 1α (HIF1α) and nerve growth factor (NGF). Transwell and wound­healing assays were performed to detect the influence of hyperglycemia on the invasion and migration ability of PC cells. An in vitro PC­dorsal root ganglion (DRG) co­culture system and an in vivo PNI sciatic nerve­infiltrating tumor model were used to evaluate the severity of PNI in hyperglycemic conditions. In the results, hyperglycemia promoted the invasion/migration ability and elevated the expression of NGF in PC by upregulating HIF1α. Moreover, in vitro short­term hyperglycemia caused little damage on the DRG axons and accelerated both the PNI of the PC and the outgrowth of the DRGs by increasing the expression of NGF via activation of HIF1α. Indeed, in vivo long­term hyperglycemia promoted the infiltration and growth of PC, and then disrupted the function of the sciatic nerve in a HIF1α­dependent manner. In conclusion, a high­glucose microenvironment promotes PNI of PC via activation of HIF1α.

Honokiol Suppresses Perineural Invasion of Pancreatic Cancer by Inhibiting SMAD2/3 Signaling.

BACKGROUND: Perineural invasion (PNI) is an important pathologic feature of pancreatic cancer, and the incidence of PNI in pancreatic cancer is 70%-100%. PNI is associated with poor outcome, metastasis, and recurrence in pancreatic cancer patients. There are very few treatments for PNI in pancreatic cancer. Honokiol (HNK) is a natural product that is mainly obtained from Magnolia species and has been indicated to have anticancer activity. HNK also has potent neurotrophic activity and may be effective for suppressing PNI. However, the potential role of HNK in the treatment of PNI in pancreatic cancer has not been elucidated. METHODS: In our study, pancreatic cancer cells were treated with vehicle or HNK, and the invasion and migration capacities were assessed by wound scratch assays and Transwell assays. A cancer cell-dorsal root ganglion coculture model was established to evaluate the effect of HNK on the PNI of pancreatic cancer. Western blotting was used to detect markers of EMT and neurotrophic factors in pancreatic tissue. Recombinant TGF-ß1 was used to activate SMAD2/3 to verify the effect of HNK on SMAD2/3 and neurotrophic factors. The subcutaneous tumor model and the sciatic nerve invasion model, which were established in transgenic engineered mice harboring spontaneous pancreatic cancer, were used to investigate the mechanism by which HNK inhibits EMT and PNI in vivo. RESULTS: We found that HNK can inhibit the invasion and migration of pancreatic cancer cells. More importantly, HNK can inhibit the PNI of pancreatic cancer. The HNK-mediated suppression of pancreatic cancer PNI was partially mediated by inhibition of SMAD2/3 phosphorylation. In addition, the inhibitory effect of HNK on PNI can be reversed by activating SMAD2/3. In vivo, we found that HNK can suppress EMT in pancreatic cancer. HNK can also inhibit cancer cell migration along the nerve, reduce the damage to the sciatic nerve caused by tumor cells and protect the function of the sciatic nerve. CONCLUSION: Our results demonstrate that HNK can inhibit the invasion, migration, and PNI of pancreatic cancer by blocking SMAD2/3 phosphorylation, and we conclude that HNK may be a new strategy for suppressing PNI in pancreatic cancer.

Matrix stiffness and its influence on pancreatic diseases.

The matrix stiffness of the extracellular matrix(ECM), which is the slow elastic force on cells, has gradually become investigated. And a higher stiffness could induce changes in cell biological behaviors and activation of internal signaling pathways. Imbalanced stiffness of ECM is associated with a number of diseases, including pancreatic disease. In this review, we discuss the components of the ECM and the increased stiffness caused by unbalanced ECM changes. Next, we describe how matrix stiffness transmits mechanical signals and what signaling pathways are altered within the cell in detail. Finally, we discuss the effect of ECM on the behavior of pancreatic diseases from the perspective of matrix stiffness.

Transcriptional Profiling Reveals the Regulatory Role of DNER in Promoting Pancreatic Neuroendocrine Neoplasms.

Wnt/ß-catenin and NOTCH signaling contribute to the pathogenesis and growth of (PanNENs). The wnt and Notch signaling pathways form an integrated signaling device termed "wntch" and regulate stochastic cell fate decisions, suggesting the essentiality of Wnt/Notch interactions in disease progression. However, the function of Wnt/Notch interactions in PanNENs is unclear. We analyzed RNA sequencing (RNA-seq) data to identify differentially expressed lncRNAs, mRNAs and pathways according to enriched Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways associated with PanNENs. RNA-seq analysis revealed that the levels of the lncRNA XLOC_221242 and the mRNA encoding Delta/Notch-like epidermal growth factor (EGF)-related receptor (DNER) were significantly increased in tumor tissues compared with normal tissues (n = 3). Protein-protein interaction (PPI) prediction combined with transcriptional profiling data analysis revealed that DNER expression levels were positively correlated with those of DNA-binding factor (RBPJ), S phase kinase-associated protein 1 (Skp1), CTNNB1 and Cadherin-2 (CDH2), which promote PanNEN tumorigenesis and progression. These results were consistent with those of immunohistochemical analysis of DNER, RBPJ, SKP1, CTNNB1, and CDH2 expression (n = 15). These findings provide compelling clinical and molecular evidence supporting the conclusion that DNER and the related RBPJ, SKP1, CTNNB1, and CDH2 signaling contribute to PanNEN tumorigenesis and progression by activating wnt/Notch interactions.

Targeting MUC15 Protein in Cancer: Molecular Mechanisms and Therapeutic Perspectives.

MUC15, a member of the mucin family, is a heavily glycosylated transmembrane protein with the primary functions of lubricating surfaces, establishing a selective molecular barrier at the epithelium and mediating signal transduction. Aberrant expression of MUC15 plays a crucial role in the progression of multiple diseases, including malignant tumors. MUC15 has been identified as a tumor suppressor, but current evidence indicate its function as an oncogene in different types of cancers. MUC15 has been shown to be involved in the development of cancer and influence cellular growth, adhesion, invasion, metastasis and immune immunomodulation. However, the precise role of MUC15 in tumour development has not been thoroughly clarified. Here, we systematically summarize the structure and function of MUC15 in cancer, and discuss its potential role in cancer treatment.

The JAM-B/c-src/MMP9 pathway is associated with progression and regulates the invasion of pancreatic cancer.

Junctional adhesion molecule B (JAM-B) is a multifunctional transmembrane protein that plays an important role in tumor progression. JAM-B is significantly upregulated in gastric cancer, melanoma cell metastasis and oral squamous cell carcinoma. JAM-2 may also function as a putative tumor suppressor in the progression and metastasis of colorectal cancer. The inconsistency of the results in different cancers has led to uncertainty regarding the role of JAM-B in carcinogenesis. For this purpose, the expression levels of JAM-B in pancreatic cancer (PanCa) tissues were associated with T stage and lymph node involvement with significant differences. A relatively high expression of JAM-B was found in PanCa cell lines by immunohistochemistry and western blot analysis. By cell transfection, JAM-B was silenced in tumor cell lines to determine cell invasion and migration abilities. Scratch wound assays and Transwell assays revealed that shJAM-B significantly decreased Panc-1 cell migration and invasion. Experiments were also conducted using a subcutaneous PanCa nude mouse model. A significant difference in tumor diameter at the injection site was found between the control group and the JAM-B low expression group. The expression levels of c-Src and MMP9 were also significantly reduced compared to that in the control group by immunohistochemistry. In conclusion, our results suggest that JAM-B secreted by cancer cells can promote progression and invasion in PanCa by upregulating the c-Src signal and related downstream proteins.

NLRP3 Inflammasome and Inflammatory Diseases.

Almost all human diseases are strongly associated with inflammation, and a deep understanding of the exact mechanism is helpful for treatment. The NLRP3 inflammasome composed of the NLRP3 protein, procaspase-1, and ASC plays a vital role in regulating inflammation. In this review, NLRP3 regulation and activation, its proinflammatory role in inflammatory diseases, interactions with autophagy, and targeted therapeutic approaches in inflammatory diseases will be summarized.