MiR-200b-3p elevates 5-FU sensitivity in cholangiocarcinoma cells via autophagy inhibition by targeting KLF4.

Cholangiocarcinoma is one of the most lethal human cancers, and chemotherapy failure is a major cause of recurrence and poor prognosis. We previously demonstrated that miR-200 family members are downregulated in clinical samples of cholangiocarcinoma and inhibit cholangiocarcinoma tumorigenesis and metastasis. However, the role of differentially expressed miR-200b-3p in 5-fluorouracil chemosensitivity remains unclear. Here, we examined how miR-200b-3p modulates 5-fluorouracil chemosensitivity in cholangiocarcinoma. We observed that miR-200b-3p was associated with 5-fluorouracil sensitivity in cholangiocarcinoma and increased 5-fluorouracil-induced mitochondrial apoptosis in cholangiocarcinoma cells. Mechanistically, miR-200b-3p suppressed autophagy in cholangiocarcinoma cells to mediate 5-fluorouracil sensitivity. Further, we identified KLF4 as an essential target of miR-200b-3p in cholangiocarcinoma. Notably, the miR-200b-3p/KLF4/autophagy pathway augmented the chemosensitivity of cholangiocarcinoma cells to 5-fluorouracil. Our findings underscore the key role of miR-200b-3p in chemosensitivity to 5-fluorouracil and highlight the miR-200b-3p/KLF4/autophagy axis as a potential therapeutic target for cholangiocarcinoma.

METTL3 Deficiency Aggravates Hepatic Ischemia/Reperfusion Injury in Mice by Activating the MAPK Signaling Pathway.

Background: Inflammatory responses, apoptosis, and oxidative stress, are key factors that contribute to hepatic ischemia/reperfusion (I/R) injury, which may lead to the failure of liver surgeries, such as hepatectomy and liver transplantation. The N6-methyladenosine (m6A) modification has been implicated in multiple biological processes, and its specific role and mechanism in hepatic I/R injury require further investigation. Methods: Dot blotting analysis was used to profile m6A levels in liver tissues at different reperfusion time points in hepatic I/R mouse models. Hepatocyte-specific METTL3 knockdown (HKD) mice were used to determine the function of METTL3 during hepatic I/R. RNA sequencing and western blotting were performed to assess the potential signaling pathways involved with the deficiency of METTL3. Finally, AAV8-TBG-METTL3 was injected through the tail vein to further elucidate the role of METTL3 in hepatic I/R injury. Results: The m6A modification levels and the expression of METTL3 were upregulated in mouse livers during hepatic I/R injury. METTL3 deficiency led to an exacerbated inflammatory response and increased cell death during hepatic I/R, whereas overexpression of METTL3 reduced the extent of liver injury. Bioinformatic analysis revealed that the MAPK pathway was significantly enriched in the livers of METTL3-deficient mice. METTL3 protected the liver from I/R injury, possibly by inhibiting the phosphorylation of JNK and ERK, but not P38. Conclusions: METTL3 deficiency aggravates hepatic I/R injury in mice by activating the MAPK signaling pathway. METTL3 may be a potential therapeutic target in hepatic I/R injury.

TRIM21-Promoted FSP1 Plasma Membrane Translocation Confers Ferroptosis Resistance in Human Cancers.

Ferroptosis, an iron-dependent form of regulated cell death driven by excessive accumulation of lipid peroxides, has become a promising strategy in cancer treatment. Cancer cells exploit antioxidant proteins, including Ferroptosis Suppressor Protein 1 (FSP1), to prevent ferroptosis. In this study, it is found that the E3 ubiquitin ligase TRIM21 bound to FSP1 and mediated its ubiquitination on K322 and K366 residues via K63 linkage, which is essential for its membrane translocation and ferroptosis suppression ability. It is further verified the protective role of the TRIM21-FSP1 axis in RSL3-induced ferroptosis in cancer cells and a subcutaneous tumor model. Moreover, TRIM21 is highly expressed in multiple gastrointestinal (GI) tumors, and its expression is further stimulated upon ferroptosis induction in cancer cells and the KPC mouse model. In summary, This study identifies TRIM21 as a negative regulator of ferroptosis through K63 ubiquitination of FSP1, which can serve as a therapeutic target to enhance the chemosensitivity of tumors based on ferroptosis induction.

A self-amplifying USP14-TAZ loop drives the progression and liver metastasis of pancreatic ductal adenocarcinoma.

With a 5-year survival rate of approximately 10%, pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid malignancies in humans. A poor understanding of the underlying biology has resulted in a lack of effective targeted therapeutic strategies. Tissue microarray and bioinformatics analyses have revealed that the downstream transcriptional coactivator of the Hippo pathway, transcriptional coactivator with PDZ-binding motif (TAZ), might be a therapeutic target in PDAC. Since pharmacological inhibition of TAZ is challenging, we performed unbiased deubiquitinase (DUB) library screening to explore the pivotal regulators of TAZ ubiquitination as potential targets in PDAC models. We found that USP14 contributed to Yes-associated protein (YAP)/TAZ transcriptional activity and stabilized TAZ but not YAP. Mechanistically, USP14 catalyzed the K48-linked deubiquitination of TAZ to promote TAZ stabilization. Moreover, TAZ facilitated the transcription of USP14 by binding to the TEA domain transcription factor (TEAD) 1/4 response element in the promoter of USP14. USP14 was found to modulate the expression of TAZ downstream target genes through a feedback mechanism and ultimately promoted cancer progression and liver metastasis in PDAC models in vitro and in vivo. In addition, depletion of USP14 led to proteasome-dependent degradation of TAZ and ultimately arrested PDAC tumour growth and liver metastasis. A strong positive correlation between USP14 and TAZ expression was also detected in PDAC patients. The small molecule inhibitor of USP14 catalytic activity, IU1, inhibited the development of PDAC in subcutaneous xenograft and liver metastasis models. Overall, our data strongly suggested that the self-amplifying USP14-TAZ loop was a previously unrecognized mechanism causing upregulated TAZ expression, and identified USP14 as a viable therapeutic target in PDAC.

Hypoxia activated HGF expression in pancreatic stellate cells confers resistance of pancreatic cancer cells to EGFR inhibition.

BACKGROUND: Epidermal growth factor receptor (EGFR) is an essential target for cancer treatment. However, EGFR inhibitor erlotinib showed limited clinical benefit in pancreatic cancer therapy. Here, we showed the underlying mechanism of tumor microenvironment suppressing the sensitivity of EGFR inhibitor through the pancreatic stellate cell (PSC). METHODS: The expression of alpha-smooth muscle actin (α-SMA) and hypoxia marker in human pancreatic cancer tissues were detected by immunohistochemistry, and their correlation with overall survival was evaluated. Human immortalized PSC was constructed and used to investigate the potential effect on pancreatic cancer cell lines in hypoxia and normoxia. Luciferase reporter assay and Chromatin immunoprecipitation were performed to explore the potential mechanisms in vitro. The combined inhibition of EGFR and Met was evaluated in an orthotopic xenograft mouse model of pancreatic cancer. FINDINGS: We found that high expression levels of α-SMA and hypoxia markers are associated with poor prognosis of pancreatic cancer patients. Mechanistically, we demonstrated that hypoxia induced the expression and secretion of HGF in PSC via transcription factor HIF-1α. PSC-derived HGF activates Met, the HGF receptor, suppressing the sensitivity of pancreatic cancer cells to EGFR inhibitor in a KRAS-independent manner by activating the PI3K-AKT pathway. Furthermore, we found that the combination of EGFR inhibitor and Met inhibitor significantly suppressed tumor growth in an orthotopic xenograft mouse model. INTERPRETATION: Our study revealed a previously uncharacterized HIF1α-HGF-Met-PI3K-AKT signaling axis between PSC and cancer cells and indicated that EGFR inhibition plus Met inhibition might be a promising strategy for pancreatic cancer treatment. FUNDING: This study was supported by The National Natural Science Foundation of China.

LncRNA FAM83H-AS1 promotes the malignant progression of pancreatic ductal adenocarcinoma by stabilizing FAM83H mRNA to protect ß-catenin from degradation.

BACKGROUND: Pancreatic ductal adenocarcinoma is prone to metastasis, resulting in short survival and low quality of life. LncRNAs are pivotal orchestrators that participate in various tumor progress. The underlying role and mechanism of lncRNA FAM83H-AS1 is still unknown in PDAC progression. METHODS: To address this issue, firstly, we profiled and analyzed the aberrant lncRNA expression in TCGA database and identified FAM83H-AS1 as the most effective one in promoting the migration of pancreatic cancer cells. Then, the expression levels of FAM83H-AS1 in patient's serum, tumor tissues and PDAC cells were detected using RT-qPCR, and FAM83H-AS1 distribution in PDAC cells was determined by performing FISH and RT-qPCR. Next, a series of in vivo and in vitro functional assays were conducted to elucidate the role of FAM83H-AS1 in cell growth and metastasis in PDAC. The regulatory relationship between FAM83H-AS1 and FAM83H (the homologous gene of FAM83H-AS1) was verified by performing protein and RNA degradation assays respectively. Co-IP assays were performed to explore the potential regulatory mechanism of FAM83H to ß-catenin. Rescue assays were performed to validate the regulation of the FAM83H-AS1/FAM83H/ß-catenin axis in PDAC progression. RESULTS: FAM83H-AS1 was highly expressed in the tumor tissues and serum of patients with PDAC, and was correlated with shorter survival. FAM83H-AS1 significantly promoted the proliferation, invasion and metastasis of PDAC cells, by protecting FAM83H mRNA from degradation. Importantly, FAM83H protein manifested the similar malignant functions as that of FAM83H-AS1 in PDAC cells, and could bind to ß-catenin. Specifically, FAM83H could decrease the ubiquitylation of ß-catenin, and accordingly activated the effector genes of Wnt/ß-catenin signaling. CONCLUSIONS: Collectively, FAM83H-AS1 could promote FAM83H expression by stabilizing its mRNA, allowing FAM83H to decrease the ubiquitylation of ß-catenin, thus resulted in an amplified FAM83H-AS1/FAM83H/ß-catenin signal axis to promote PDAC progression. FAM83H-AS1 might be a novel prognostic and therapeutic target for combating PDAC.

Inhibition of PI3K/AKT signaling via ROS regulation is involved in Rhein-induced apoptosis and enhancement of oxaliplatin sensitivity in pancreatic cancer cells.

Several natural products have been demonstrated to both enhance the anti-tumor efficacy and alleviate the side effects of conventional chemotherapy drugs. Rhein, a main constituent of the Chinese herb rhubarb, has been shown to induce apoptosis in various cancer types. However, the exact pharmacological mechanisms controlling the influence of Rhein on chemotherapy drug effects in pancreatic cancer (PC) remain largely undefined. In this study, we found that Rhein inhibited the growth and proliferation of PC cells through G1 phase cell cycle arrest. Moreover, Rhein induced caspase-dependent mitochondrial apoptosis of PC cells through inactivation of the PI3K/AKT pathway. Combination treatment of Rhein and oxaliplatin synergistically enhanced apoptosis of PC cells through increased generation of intracellular reactive oxygen species (ROS) and inactivation of the PI3K/AKT pathway. Pre-treatment with the ROS scavenger N-acetyl-L-cysteine attenuated the combined treatment-induced apoptosis and restored the level of phosphorylated AKT, indicating that ROS is an upstream regulator of the PI3K/AKT pathway. The combination therapy also exhibited stronger anti-tumor effects compared with single drug treatments in vivo. Taken together, these data demonstrate that Rhein can induce apoptosis and enhance the oxaliplatin sensitivity of PC cells, suggesting that Rhein may be an effective strategy to overcome drug resistance in the chemotherapeutic treatment of PC.

PINK1/Parkin-Mediated Mitophagy Regulation by Reactive Oxygen Species Alleviates Rocaglamide A-Induced Apoptosis in Pancreatic Cancer Cells.

Pancreatic cancer (PC) is one of the most lethal diseases, and effective treatment of PC patients remains an enormous challenge. Rocaglamide A (Roc-A), a bioactive molecule extracted from the plant Aglaia elliptifolia, has aroused considerable attention as a therapeutic choice for numerous cancer treatments. Nevertheless, the effects and underlying mechanism of Roc-A in PC are still poorly understood. Here, we found that Roc-A inhibited growth and stimulated apoptosis by induction of mitochondria dysfunction in PC. Moreover, Roc-A accelerated autophagosome synthesis and triggered mitophagy involving the PTEN-induced putative kinase 1 (PINK1)/Parkin signal pathway. We also demonstrated that inhibition of autophagy/mitophagy can sensitize PC cells to Roc-A. Finally, Roc-A treatment results in an obvious accumulation of reactive oxygen species (ROS), and pretreatment of cells with the reactive oxygen species scavenger N-acetylcysteine reversed the apoptosis and autophagy/mitophagy induced by Roc-A. Together, our results elucidate the potential mechanisms of action of Roc-A. Our findings indicate Roc-A as a potential therapeutic agent against PC and suggest that combination inhibition of autophagy/mitophagy may be a promising therapeutic strategy in PC.

TFEB-driven autophagy potentiates TGF-ß induced migration in pancreatic cancer cells.

BACKGROUND: Pancreatic ductal adenocarcinoma is one of the most aggressive cancers, with a 5-year survival rate of less than 8%. The complicated tumor microenvironment, particularly TGF-ß, provides possible convenience for the progression of PC cells. TGF-ß regulates critical cellular processes, including autophagy. However, the mechanism and effects of TGF-ß-mediated autophagy are still poorly understood. METHODS: Bioinformatics analysis, western blot, transmission electron microscopy and confocal microscopy were used to identify that TFEB is the key factors in TGF-ß-induced autophagy. The biological effects of TFEB-driven autophagy were investigated in vitro using transwell and wound healing assays and in vivo using liver metastasis and LSL-KrasG12D/Pdx1-Cre mice models. Luciferase assays and motif analysis were used to assess regulation of RAB5A gene promoter activity by TGF-ß-induced TFEB. TFEB levels were measured by real-time PCR, western blot and immunohistochemical staining in clinical pancreatic ductal adenocarcinoma tissues. RESULTS: We demonstrated that TGF-ß induces TFEB expression via the canonical smad pathway in Smad4-positive PC cells and facilitates TFEB-mediated autophagic activation. TFEB-driven autophagy caused by TGF-ß regulates RAB5A-dependent endocytosis of Itgα5 and promotes progression of PC cells. We further showed that enhanced TFEB expression and its direct target RAB5A both predict poor prognosis in PC patients. CONCLUSIONS: Our findings reveal TFEB-driven autophagy is required for TGF-ß induced migration and metastasis of PC cells by promoting endocytosis of Itgα5ß1 and focal adhesion disassembly through the TGF-ß-TFEB-RAB5A axis. Our results highlight the potential utility of suppressing TFEB-driven autophagy to block PC metastasis.

Danthron suppresses autophagy and sensitizes pancreatic cancer cells to doxorubicin.

In contrast to the steady increase in survival observed for most cancer types, advances have been slow for pancreatic cancers. Current chemotherapy has limited benefits for patients with pancreatic cancer. Therefore, there is an urgent need for effective pancreatic cancer treatment strategies. At present, targeting the autophagic pathway is regarded as a promising new strategy for cancer treatment. Danthron (1,8-dihydroxyanthrquinone), a component from Rheum palmatum L. (polygonaceae), has several biological activities. However, the inhibition of autophagy by danthron has never been recognized, previously.Here we find that danthron may prevent autophagy, inhibit proliferation and induce apoptosis in pancreatic cancer cells in vitro. Autophagy induced by doxorubicin plays a protective role in pancreatic cancer cells and inhibition of autophagy by chloroquine or silencing autophagy protein 5 (Atg5) may chemosensitize pancreatic cancer cell lines to doxorubicin. Similarly, inhibition of autophagy by danthron also enhances toxicity of doxorubicin to pancreatic cancer cells. These results indicate that danthron has an anticancer effect and can sensitize the chemotherapeutic effect of doxorubicin on pancreatic cancer cells. These findings also suggest that inhibition of autophagy may be an effective way to promote the chemotherapy of pancreatic cancer.

Meta-analysis on resected pancreatic cancer: a comparison between adjuvant treatments and gemcitabine alone.

BACKGROUND: Pancreatic cancer is a highly malignant tumor with a poor prognosis. Chemotherapy such as gemcitabine is still an important treatment. Gemcitabine (Gem) may prolong survival time and delay the development of recurrent disease after complete resection of pancreatic cancer. Currently, some control studies have been performed between certain drugs and gemcitabine monotherapy after pancreatic cancer surgery, but the outcomes were uncertain. Here, we implemented meta-analysis to compare the efficacy between adjuvant treatments and gemcitabine monotherapy in patients with resected pancreatic cancer. METHODS: PubMed, Embase and the Central Registry of Controlled Trials of the Cochrane Library searches were undertaken to identify randomized controlled trials (RCTs). Date of search ranged from January 1997 to December 2017. The meta-analysis included six RCTs. The major endpoints involved overall survival (OS), disease-free survival/progress free survival/relapse-free survival (DFS/PFS/RFS) and grade 3-4 toxicity. RESULTS: Pooled meta-analytic estimates were derived using random-effects model. Subgroup analysis used fixed-effects model. The outcome showed that there was no difference in OS (hazard ratio (HR), 0.87; 95% CI, 0.70-1.07; P = 0.19) and DFS (HR, 0.85; 95% CI, 0.71-1.02; P = 0.08) between the adjuvant treatments group (fluorouracil+folinic acid, S-1, gemcitabine+capecitabine, gemcitabine+erlotinib and gemcitabine+uracil/tegafur) and Gem monotherapy group. However, the subgroup analysis showed that only S-1 chemotherapy, which is an oral fluoropyrimidine agent containing tegafur, gimeracil and oteracil, was significant in OS (HR, 0.59; 95% CI, 0.46-0.74; P < 0.0001) and DFS (HR, 0.63; 95% CI, 0.52-0.75; P < 0.00001) compared with Gem alone. Toxicity analysis showed there was an increased incidence of grade 3/4 diarrhea (risk ratio (RR), 5.11; 95%CI, 3.24-8.05; P < 0.00001) and decreased incidence of grade 3/4 leucopenia (RR, 0.55; 95%CI, 0.31-0.98; P = 0.04), thrombocytopenia (RR, 0.61; 95%CI, 0.39-0.97; P = 0.04) in adjuvant treatments group. Neutropenia (RR, 0.69; 95%CI, 0.36-1.29; P = 0.24) and fatigue (RR, 1.29; 95%CI, 0.95-1.77; P = 0.11) for patients between the two groups were not significantly different. CONCLUSIONS: In our meta-analysis, a significant survival benefit is only observed in the S-1 regimen, but the results are yet to be determined. Optimal cytotoxicity or targeted drug regimens need further validation in clinical trials in the future.

Alantolactone induces apoptosis and improves chemosensitivity of pancreatic cancer cells by impairment of autophagy-lysosome pathway via targeting TFEB.

The lysosome is emerging as a central regulator of the autophagic process, which plays a critical role in tumor growth and chemoresistance. Alantolactone, which is a natural compound produced by Inula helenium, has been shown to induce apoptosis in numerous cancer types. However, the mechanism by which alantolactone regulates apoptosis is still poorly understood. In this work, we observed that alantolactone caused the accumulation of autophagosomes due to impaired autophagic degradation and substantially inhibited the activity and expression of CTSB/CTSD proteins that when depleted caused lysosomal dysfunction. Furthermore, we found that alantolactone inhibited the proliferation of pancreatic cancer cells in vitro and in vivo and enhanced the chemosensitivity of pancreatic cancer cells to oxaliplatin. In addition, a reduction in TFEB levels was a critical event in the apoptosis and cell death caused by alantolactone. Our data demonstrated that alantolactone, which impaired autophagic degradation, was a pharmacological inhibitor of autophagy in pancreatic cancer cells and markedly enhanced the chemosensitivity of pancreatic cancer cells to oxaliplatin.

A Five-microRNA Signature for Survival Prognosis in Pancreatic Adenocarcinoma based on TCGA Data.

Novel biomarkers for pancreatic adenocarcinoma are urgently needed because of its poor prognosis. Here, by using The Cancer Genome Atlas (TCGA) RNA-seq data, we evaluated the prognostic values of the differentially expressed miRNAs and constructed a five-miRNA signature that could effectively predict patient overall survival (OS). The Kaplan-Meier overall survival curves of two groups based on the five miRNAs were notably different, showing overall survival in 10.2% and 47.8% at five years for patients in high-risk and low-risk groups, respectively. The ROC curve analysis achieved AUC of 0.775, showing good sensitivity and specificity of the five-miRNA signature model in predicting pancreatic adenocarcinoma patient survival risk. The functional enrichment analysis suggested that the target genes of the miRNA signature may be involved in various pathways related to cancer, including PI3K-Akt, TGF-ß, and pluripotent stem cell signaling pathways. Finally, we analyzed expression of the five specific miRNAs in the miRNA signature, and validated the reliability of the results in 20 newly diagnosed pancreatic adenocarcinoma patients using qRT-PCR. The expression results of qRT-PCR were consistent with the TCGA results. Taken together, these findings suggested that the five-miRNA signature (hsa-miR-203, hsa-miR-424, hsa-miR-1266 hsa-miR-1293, and hsa-miR-4772) could be used as a prognostic marker for pancreatic adenocarcinoma.