Gemcitabine resistance in pancreatic ductal adenocarcinoma. Drug Resist Updat. 2015;23:55-68. [PMID: 26690340 DOI: 10.1016/j.drup.2015.10.002]

New Therapy Options for Neuroendocrine Carcinoma of the Pancreas—The Emergent Substance GP-2250 and Gemcitabine Prove to Be Highly Effective without the Development of Secondary Resistances In Vitro and In Vivo

Simple Summary

Neuroendocrine carcinoma of the pancreas is a highly aggressive form of neuroendocrine tumor associated with poor survival and increasing occurrence. GP-2250 is an emergent substance showing antineoplastic properties, especially in combination with Gemcitabine. This study was the first to evaluate the antineoplastic effects of GP-2250 on pancreatic neuroendocrine carcinoma. The combination of GP-2250 and Gemcitabine showed highly synergistic effects in a cell culture model, as well as in mice, without the development of secondary resistances. These findings form the basis for further clinical evaluation of a highly promising combination therapy.

Abstract

Neuroendocrine carcinoma of the pancreas (pNEC) is an aggressive form of neuroendocrine tumor characterized by a rising incidence without an increase in survival rates. GP-2250 is an oxathiazinane derivate possessing antineoplastic effects, especially in combination with Gemcitabine on the pancreatic adenocarcinoma. The cytotoxic effects of the monotherapy of GP-2250 (GP-2250_mono) and Gemcitabine (Gem_mono), as well as the combination therapy of both, were studied in vitro using an MTT-assay on the QGP-1 and BON-1 cell lines, along with in vivo studies on a murine xenograft model of QGP-1 and a patient-derived xenograft model (PDX) of Bo99. In vitro, Gem_mono and GP-2250_mono showed a dose-dependent cytotoxicity. The combination of GP-2250 and Gemcitabine exhibited highly synergistic effects. In vivo, the combination therapy obtained a partial response in QGP-1, while GP-2250_mono and Gem_mono showed progressive disease or stable disease, respectively. In Bo99 PDX, the combination therapy led to a partial response, while the monotherapy resulted in progressive disease. No development of secondary resistances was observed, as opposed to monotherapy. This study was the first to evaluate the effects of the emerging substance GP-2250 on pNEC. The substance showed synergism in combination with Gemcitabine. The combination therapy proved to be effective in vitro and in vivo, without the development of secondary resistances.

Gemcitabine-Loaded Albumin Nanoparticle Exerts An Antitumor Effect on Gemcitabine-Resistant Pancreatic Cancer Cells Induced by MDR1 and MRP1 Overexpression in Vitro

Purpose

Gemcitabine (GEM) is the first-line chemotherapeutic drug for pancreatic cancer treatment in clinical practice. However, many reasons can reduce the efficacy of GEM, among which the high expression of ATP-binding cassette (ABC) transporters is a significant factor. In this study, we aimed to investigate the antitumor effect of gemcitabine-loaded human serum albumin nanoparticle (GEM-HSA-NP) on GEM-resistant pancreatic cancer cells induced by the high expression of ABC transporters, namely multidrug resistance protein 1/P-gp/ABCB1 (MDR1) and multidrug resistance-associated protein 1/ ABCC1 (MRP1).

Methods

MDR1 and MRP1 were stably overexpressed via lentiviral transduction in the pancreatic cancer cell lines BxPC3 and PANC1. Proliferation inhibition assays, cell cycle arrest and apoptosis analyses were conducted to examine the antitumor effect of GEM-HSA-NP. In addition, intracellular ATP levels were determined to explore the potential mechanisms implicated preliminarily.

Results

When administered to GEM-resistant cancer cells, GEM-HSA-NP displayed its antitumor effect by promoting the inhibition of proliferation, cell cycle arrest, and apoptosis induction. Intracellular ATP depletion, caused by the albumin component of GEM-HSA-NP was proposed to be potentially involved in the modulation of ABC transporter activity.

Conclusion

GEM-HSA-NP can effectively overcome GEM-resistance induced by MDR1 and MRP1 overexpression, which highlights its potential value in a clinical setting.

Hsa-miR-3178/RhoB/PI3K/Akt, a novel signaling pathway regulates ABC transporters to reverse gemcitabine resistance in pancreatic cancer

BACKGROUND

Although gemcitabine has been considered as the first-line drug for advanced pancreatic cancer (PC), development of resistance to gemcitabine severely limits the effectiveness of this chemotherapy, and the underlying mechanism of gemcitabine resistance remains unclear. Various factors, such as ATP binding cassette (ABC) transporters, microRNAs and their downstream signaling pathways are included in chemoresistance to gemcitabine. This study investigated the potential mechanisms of microRNAs and ABC transporters related signaling pathways for PC resistance to gemcitabine both in vivo and in vitro.

METHODS

Immunohistochemistry and Western blotting were applied to detect the expression of ABC transporters. Molecular docking analysis was performed to explore whether gemcitabine interacted with ABC transporters. Gain-of-function and loss-of-function analyses were performed to investigate the functions of hsa-miR-3178 in vitro and in vivo. Bioinformatics analysis, Western blotting and dual-luciferase reporter assay were used to confirm the downstream regulatory mechanisms of hsa-miR-3178.

RESULTS

We found that P-gp, BCRP and MRP1 were highly expressed in gemcitabine-resistant PC tissues and cells. Molecular docking analysis revealed that gemcitabine can bind to the ABC transporters. Hsa-miR-3178 was upregulated in gemcitabine resistance PANC-1 cells as compared to its parental PANC-1 cells. Moreover, we found that hsa-miR-3178 promoted gemcitabine resistance in PC cells. These results were also verified by animal experiments. RhoB was down-regulated in gemcitabine-resistant PC cells and it was a downstream target of hsa-miR-3178. Kaplan-Meier survival curve showed that lower RhoB expression was significantly associated with poor overall survival in PC patients. Rescue assays demonstrated that RhoB could reverse hsa-miR-3178-mediated gemcitabine resistance. Interestingly, hsa-miR-3178 promoted gemcitabine resistance in PC by activating the PI3K/Akt pathway-mediated upregulation of ABC transporters.

CONCLUSIONS

Our results indicate that hsa-miR-3178 promotes gemcitabine resistance via RhoB/PI3K/Akt signaling pathway-mediated upregulation of ABC transporters. These findings suggest that hsa-miR-3178 could be a novel therapeutic target for overcoming gemcitabine resistance in PC.

c-Myc-PD-L1 Axis Sustained Gemcitabine-Resistance in Pancreatic Cancer

Pancreatic cancer ranks fourth among cancer-related deaths, with a 5-years overall survival rate being below 10%. Gemcitabine (dFdC) has been considered the first-line drug for patients with pancreatic cancer. However, the clinical effectiveness is less than 20% due to drug resistance. Most importantly, overwhelming evidence suggested c-Myc and PD-L1 were generally highly expressed in pancreatic cancer patients. However, whether dFdC-resistant pancreatic cancer is associated with c-Myc and PD-L1 has not been elucidated. In our present study, we found that the expression of c-Myc and PD-L1 was markedly increased in pancreatic tumor tissues compared with adjacent tissues. Similarly, c-Myc and PD-L1 expression were also remarkably elevated in dFdC-resistant Panc-1 cells compared with parental cells. In addition, dFdC sensitivity was enhanced by the combination of dFdC and c-Myc inhibitors in Panc-1 cells. Interestingly, its sensitivity was reduced when c-Myc was overexpressed. Moreover, PD-L1 protein expression was dramatically down-regulated when treated with c-Myc inhibitors. Furthermore, artesunate (ARTS) screened from 18 compounds could reverse dFdC resistance in combination with dFdC in dFdC-resistant Panc-1 cells in vitro and suppressed DMBA-induced pancreatic cancer in vivo. In summary, our data revealed that the mechanism of dFdC resistance may be that c-Myc overexpression contributed to increased PD-L1 expression, and ARTS could overcome dFdC-resistant pancreatic cancer by inhibiting c-Myc and PD-L1. Our findings not only suggest c-Myc and PD-L1 as novel prognostic biomarkers in dFdC-resistant pancreatic cancer, but also provide ARTS as a promising candidate for overcoming dFdC resistance.

RhoGDI2 induced malignant phenotypes of pancreatic cancer cells via regulating Snail expression

BACKGROUND

Rho GDP dissociation inhibitor 2 (RhoGDI2) has been shown to contribute to the aggressive phenotypes of human cancers, such as tumor metastasis and chemoresistance.

OBJECTIVE

This study aimed to assess the effects of RhoGDI2 on tumor progression and chemoresistance in pancreatic cancer cells.

METHODS

The expression of RhoGDI2 in pancreatic cancer cells was detected by Western blot analysis. Gain-of-function and loss-of-function approaches were done to examine the malignant phenotypes of the RhoGDI2-expressing or RhoGDI2-depleting cells. The correlation between RhoGDI2 and Snail was also analyzed.

RESULTS

Differential expression of RhoGDI2 protein in pancreatic cancer cell lines was identified. Gain-of-function and loss-of-function experiments showed that RhoGDI2 induced the malignant phenotypes of pancreatic cancer cells, including proliferation, migration, invasion, and gemcitabine (GEM) chemoresistance. The upregulation of RhoGDI2 stimulated the expression of Snail, resulting in the altered expression of epithelial marker E-cadherin and mesenchymal marker Vimentin, which were characteristics of the tumorigenic activity of epithelial-mesenchymal transition. The expression of RhoGDI2 and Snail was upregulated in clinical tumor samples, and higher expression of RhoGDI2 or Snail was significantly associated with poor patient survival in pancreatic ductal adenocarcinoma (PDAC).

CONCLUSION

The findings indicated that RhoGDI2 promoted GEM resistance and tumor progression in pancreatic cancer and that RhoGDI2 might be a potential therapeutic target in patients with PDAC.

Redox-responsive self-assembled polymeric nanoprodrug for delivery of gemcitabine in B-cell lymphoma therapy

Gemcitabine, as a standard and classic strategy for B-cell lymphoma in the clinic, is limited by its poor pharmacodynamics. Although stimuli-responsive polymeric nanodelivery systems have been widely investigated in the past decade, issues such as complicated procedures, low loading capacity, and uncontrollable release kinetics still hinder their clinical translation. In view of the above considerations, we attempt to construct hyperbranched polyprodrug micelles with considerable drug loading via simple procedures and make use of the particularity of the tumor microenvironment to ensure that the micelles are "inactivated" in normal tissues and "activated" in the tumor microenvironment. Hence, in this work, a redox-responsive polymeric gemcitabine-prodrug (GEM-S-S-PEG) was one-pot synthesized via facile esterification and acylation. The self-assembled subsize (< 100 nm) GEM-S-S-PEG (GSP NPs) with considerable loading capacity (≈ 24.6%) exhibited on-demand and accurate control of gemcitabine release under a simulated tumor microenvironment and thus significantly induced the apoptosis of B-cell lymphoma in vitro. Moreover, in the A20 tumor xenograft murine model, GSP NPs efficiently decreased the expansion of tumor tissues with minimal systemic toxicity. In summary, these redox-responsive and self-assembling GSP NPs with a facile one-pot synthesis procedure may hold great potency in clinical translation for enhanced chemotherapy of B-cell lymphoma. STATEMENT OF SIGNIFICANCE: A redox-responsive polymeric gemcitabine-prodrug (GEM-S-S-PEG) was one-pot synthesized via facile esterification and acylation. The self-assembled subsize (< 100 nm) GEM-S-S-PEG (GSP NPs) exhibited significant tumor therapeutic effects in vitro and in vivo. The polyprodrug GEM-S-S-PEG prepared in this study shows the great potential of redox-responsive nanodrugs for antitumor activity, which provides a reference value for the optimization of the design of functional polyprodrugs.

Long Non-Coding RNAs in Pancreatic Cancer: Biologic Functions, Mechanisms, and Clinical Significance

Despite tremendous efforts devoted to research in pancreatic cancer (PC), the mechanism underlying the tumorigenesis and progression of PC is still not completely clear. Additionally, ideal biomarkers and satisfactory therapeutic strategies for clinical application in PC are still lacking. Accumulating evidence suggests that long non-coding RNAs (lncRNAs) might participate in the pathogenesis of diverse cancers, including PC. The abnormal expression of lncRNAs in PC is considered a vital factor during tumorigenesis that affects tumor cell proliferation, migration, invasion, apoptosis, angiogenesis, and drug resistance. With this review of relevant articles published in recent years, we aimed to summarize the biogenesis mechanism, classifications, and modes of action of lncRNAs and to review the functions and mechanisms of lncRNAs in PC. Additionally, the clinical significance of lncRNAs in PC was discussed. Finally, we pointed out the questions remaining from recent studies and anticipated that further investigations would address these gaps in knowledge in this field.

Circular RNA circ-MTHFD1L induces HR repair to promote gemcitabine resistance via the miR-615-3p/RPN6 axis in pancreatic ductal adenocarcinoma

BACKGROUND

Chemoresistance of pancreatic cancer is the main reason for the poor treatment effect of pancreatic cancer patients. Exploring chemotherapy resistance-related genes has been a difficult and hot topic of oncology. Numerous studies implicate the key roles of circular RNAs (circRNAs) in the development of pancreatic cancer. However, the regulation of circRNAs in the process of pancreatic ductal adenocarcinoma (PDAC) chemotherapy resistance is not yet fully clear.

METHODS

Based on the cross-analysis of the Gene Expression Omnibus (GEO) database and the data of our center, we explored a new molecule, hsa_circ_0078297 (circ-MTHFD1L), related to chemotherapy resistance. QRT-PCR was used to detect the expression of circRNAs, miRNAs, and mRNAs in human PDAC tissues and their matched normal tissues. The interaction between circ-MTHFD1L and miR-615-3p/RPN6 signal axis was confirmed by a series of experiments such as Dual-luciferase reporter assay, fluorescence in situ hybridization (FISH) RNA immunoprecipitation (RIP) assays.

RESULTS

Circ-MTHFD1L was significantly increased in PDAC tissues and cells. And in PDAC patients, the higher the expression level of circ-MTHFD1L, the worse the prognosis. Mechanism analysis showed that circ-MTHFD1L, as an endogenous miR-615-3p sponge, upregulates the expression of RPN6, thereby promoting DNA damage repair and exerting its effect on enhancing gemcitabine chemotherapy resistance. More importantly, we also found that Silencing circ-MTHFD1L combined with olaparib can increase the sensitivity of pancreatic cancer to gemcitabine.

CONCLUSION

Circ-MTHFD1L maintains PDAC gemcitabine resistance through the miR-615-3p/RPN6 signal axis. Circ-MTHFD1L may be a molecular marker for the effective treatment of PDAC.

Potential roles of exosomal non-coding RNAs in chemoresistance in pancreatic cancer

Pancreatic cancer (PC) is one of the deadliest digestive system tumors in the world, primarily attributed to difficulty in early diagnosis, early metastasis, and insen-sitivity to chemotherapy. The survival of advanced PC patients can be improved by chemotherapy, including gemcitabine, platinum drugs, and 5-fluorouracil, and targeted therapy such as PARP inhibitors. Nevertheless, primary or acquired drug resistance ultimately leads to treatment failure and poor prognosis in patients with PC. The mechanism underlying drug resistance in PC is complex and has not been fully elucidated. Recent studies have indicated that exsomes are the best natural carrier of non-coding RNAs (ncRNAs). They can regulate drug resistance by transporting ncRNAs. Accumulating evidence has demonstrated that exosomal ncRNAs, including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), play an crucial role in regulating resistance to chemotherapy drugs in PC. In this review, we systematically focus on the emerging role and regulatory mechanisms of exosomal ncRNAs in influencing chemotherapy resistance in PC. We believe that exosomal ncRNAs can be considered as potential biomarkers for the diagnosis and prognosis of PC as well as new therapeutic targets.

4-Acetylantroquinonol B enhances cell death and inhibits autophagy by downregulating the PI3K/Akt/MDR1 pathway in gemcitabine-resistant pancreatic cancer cells

Gemcitabine (GEM) is a typical chemotherapeutic drug used to treat pancreatic cancer, but GEM resistance develops within weeks after chemotherapy. Hence, the development of a new strategy to overcome drug resistance is urgent. 4-Acetylantroquinonol B (4-AAQB), a ubiquinone derived from Taiwanofungus camphoratus, has hepatoprotective, anti-obesity, and antitumor activities. However, the role of 4-AAQB in enhancing GEM sensitivity is unclear. This study aimed to determine the underlying mechanisms by which 4-AAQB enhances cytotoxicity and GEM sensitivity. Cell viability was dramatically reduced by 4-AAQB (2 and 5 µM) treatment in the MiaPaCa-2 and GEM-resistant MiaPaCa-2 (MiaPaCa-2GEMR) human pancreatic cancer cells. 4-AAQB led to cell cycle arrest, upregulated the levels of reactive oxygen species (ROS), promoted apoptosis, and inhibited autophagy, which subsequently enhanced GEM chemosensitivity by suppressing the receptor for advanced glycation end products (RAGE)/high mobility group box 1 (HMGB1)-initiated PI3K/Akt/multidrug resistance protein 1 (MDR1) signaling pathway in both cell lines. Vascular endothelial growth factor A (VEGFA) expression, cell migration, and invasion were also inhibited by the 4-AAQB incubation. Overall, this combination treatment strategy might represent a novel approach for GEM-resistant pancreatic cancer.

Lucidone inhibits autophagy and MDR1 via HMGB1/RAGE/PI3K/Akt signaling pathway in pancreatic cancer cells

Gemcitabine (GEM) drug resistance remains a difficult challenge in pancreatic ductal adenocarcinoma (PDAC) treatment. Therefore, identifying a safe and effective treatment strategy for PDAC is urgent. Lucidone is a natural compound extracted from the fruits of Lindera erythrocarpa Makino. However, the role of lucidone in PDAC inhibition remains unclear. In addition, high-mobility group box 1 (HMGB1) and receptor for advanced glycation end products (RAGE) are involved in multidrug resistance protein 1 (MDR1) regulation and GEM resistance. Thus, this study aimed to explore the function of lucidone in tumor cytotoxicity and chemosensitivity through the suppression of RAGE-initiated signaling in PDAC cells. The data showed that lucidone significantly promoted apoptotic cell death and inhibited the expression of autophagic proteins (Atg5, Beclin-1, LC3-II, and Vps34) and MDR1 by inhibiting the HMGB1/RAGE/PI3K/Akt axis in both MIA Paca-2 cells and MIA Paca-2GEMR cells (GEM-resistant cells). Notably, convincing data were also obtained in experiments involving RAGE-specific siRNA transfection. In addition, remarkable cell proliferation was observed after treatment with lucidone combined with GEM, particularly in MIA Paca-2GEMR cells, indicating that lucidone treatment enhanced chemosensitivity. Collectively, this study provided the underlying mechanism by which lucidone treatment inhibited HMGB1/RAGE-initiated PI3K/Akt/MDR1 signaling and consequently enhanced chemosensitivity in PDAC.

Coumarin-Palladium(II) Complex Acts as a Potent and Non-Toxic Anticancer Agent against Pancreatic Carcinoma Cells

Pancreatic carcinoma still represents one of the most lethal malignant diseases in the world although some progress has been made in treating the disease in the past decades. Current multi-agent treatment options have improved the overall survival of patients, however, more effective treatment strategies are still needed. In this paper we have characterized the anticancer potential of coumarin-palladium(II) complex against pancreatic carcinoma cells. Cells viability, colony formation and migratory potential of pancreatic carcinoma cells were assessed in vitro, followed by evaluation of apoptosis induction and in vivo testing on zebrafish. Presented results showed remarkable reduction in pancreatic carcinoma cells growth both in vitro and in vivo, being effective at micromolar concentrations (0.5 μM). Treatments induced apoptosis, increased BAX/BCL-2 ratio and suppressed the expression of SOX9 and SOX18, genes shown to be significantly up-regulated in pancreatic ductal adenocarcinoma. Importantly, treatments of the zebrafish-pancreatic adenocarcinoma xenografts resulted in significant reduction in tumor mass, without provoking any adverse toxic effects including hepatotoxicity. Presented results indicate the great potential of the tested compound and the perspective of its further development towards pancreatic cancer therapy.

LEM domain containing 1 promotes pancreatic cancer growth and metastasis by p53 and mTORC1 signaling pathway

Pancreatic cancer (PC) is a common type of malignancy originating from the epithelium of the pancreatic duct, with the most lethal feature and worst prognosis. LEM domain containing 1 (LEMD1) is overexpressed in multiple tumor tissues and plays a key role in cancer carcinogenesis and progression. However, little is known about the potential of LEMD1 in PC. In this study, we explored the clinical values, as well as the potential roles and mechanisms of LEMD1 in PC. We, for the first time, showed that LEMD1 was upregulated in PC and negatively correlated with the overall and disease-free survival of patients with PC. Of the function, LEMD1 knockdown inhibited cancer cell growth, migration and invasion, while LEMD1 overexpression promoted tumor aggressiveness. The tumor-promoting influences of LEMD1 in PC were also proved by in vivo assays. Mechanistically, GSEA identified that LEMD1 promoted PC aggressiveness, as well as affecting cell cycle dysregulation and apoptosis resistance, by p53 suppression and the activation of the mTORC1 signal pathway. In short, LEMD1 could serve as a valuable prognostic candidate and a potential therapeutic target of PC.Abbreviations: ATCC: American Type Culture Collection; CCK-8: Cell counting kit 8; CDK: Cyclin-dependent kinases; CTA: Cancer-testis antigen; DMEM: Dulbecco's Modified Eagle's Medium; ECL: enhanced chemiluminescence; FBS: Fetal bovine serum; GEO: Gene Expression Omnibus; LEMD1: LEM domain containing 1; mTOR: mammalian target of rapamycin; NC: Negative control; PC: Pancreatic cancer; PVDF: Polyvinylidene difluoride membranes; qRT-PCR: Quantitative real-time polymerase chain reaction; SDS-PAGE: Sodium dodecyl sulfate polyacrylamide gel electrophoresis; SD: Standard deviation; SKP2: S-Phase kinase-associated protein 2; TAA: Tumor-associated antigen; TBST: Tris-buffered Saline Tween-20; TCGA: The Cancer Genome Atlas.

Recent advances in targeted drug delivery for the treatment of pancreatic ductal adenocarcinoma

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) has become a serious health problem with high impact worldwide. The heterogeneity of PDAC makes it difficult to apply drug delivery systems (DDS) used in other cancer models, for example, the poorly developed vascular system makes anti-angiogenic therapy ineffective. Due to its various malignant pathological changes, drug delivery against PDAC is a matter of urgent concern. Based on this situation, various drug delivery strategies specially designed for PDAC have been generated.

AREAS COVERED

This review will briefly describe how delivery systems can be designed through nanotechnology and formulation science. Most research focused on penetrating the stromal barrier, exploiting and alleviating the hypoxic microenvironment, targeting immune cells, or designing vaccines, and combination therapies. This review will summarize the ways to reverse the malignant pathological features of PDAC and hopefully provide ideas for subsequent studies.

EXPERT OPINION

Drug delivery systems designed to achieve penetrating functions or to alleviate hypoxia and activate immunity have achieved good therapeutic results in animal models in several studies. In future studies, there is a need to deliver PDAC therapeutics in a more precise manner, or the use of drug carriers for multiple functions simultaneously, are potential therapeutic strategy.

Identification of a Pyroptosis-Related Gene Signature and Effect of Silencing the CHMP4C and CASP4 in Pancreatic Adenocarcinoma

Background

Pancreatic adenocarcinoma (PAAD) is a highly malignant tumor with an extremely poor prognosis. Pyroptosis has been demonstrated to play an important role in tumor prognosis. However, the expression of pyroptosis-related genes in PAAD and their correlations with prognosis remains unclear.

Methods

In this study, the 36 pyroptosis-related genes that were differentially expressed between normal pancreatic tissues and PAAD tissues were identified via the “limma” R package. Based on these differentially expressed genes (DEGs), a five-gene signature was established by applying the least absolute shrinkage and selection operator Cox regression in the TCGA cohort and was validated in the GEO cohort. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses of DEGs based on the risk model indicated that immune-associated biological processes and pathways were enriched. In vivo, we detected the expressions of CASP4 and CHMP4C by immunohistochemistry in tumor tissues and adjacent normal tissues. In vitro, we silenced CASP4 and CHMP4C to explore their effects on pancreatic cancer cells.

Results

PAAD patients in the low-risk group showed significantly higher survival possibilities than those in the high-risk group. The expressions of CASP4 and CHMP4C in tumor tissue were higher than those in the adjacent normal tissues in vivo. The knockdown of CASP4 significantly inhibited the invasion and migration but not the proliferation of PANC-1 cells. The knockdown of CHMP4C obviously inhibited the proliferation, migration, and invasion of PANC-1 cells.

Conclusion

Pyroptosis-related genes play important roles in predicting the prognosis of PAAD, and CASP4 and CHMP4C affect the metastasis of PAAD.

A Novel Small Molecular Prostaglandin Receptor EP4 Antagonist, L001, Suppresses Pancreatic Cancer Metastasis

Metastatic pancreatic cancer remains a major clinical challenge, emphasizing the urgent need for the exploitation of novel therapeutic approaches with superior response. In this study, we demonstrate that the aberrant activation of prostaglandin E₂ (PGE₂) receptor 4 (EP4) is a pro-metastatic signal in pancreatic cancer. To explore the therapeutic role of EP4 signaling, we developed a potent and selective EP4 antagonist L001 with single-nanomolar activity using a panel of cell functional assays. EP4 antagonism by L001 effectively repressed PGE₂-elicited cell migration and the invasion of pancreatic cancer cells in a dose-dependent manner. Importantly, L001 alone or combined with the chemotherapy drug gemcitabine exhibited remarkably anti-metastasis activity in a pancreatic cancer hepatic metastasis model with excellent tolerability and safety. Mechanistically, EP4 blockade by L001 abrogated Yes-associated protein 1 (YAP)-driven pro-metastatic factor expression in pancreatic cancer cells. The suppression of YAP’s activity was also observed upon L001 treatment in vivo. Together, these findings support the notions that EP4–YAP signaling axis is a vital pro-metastatic pathway in pancreatic cancer and that EP4 inhibition with L001 may deliver a therapeutic benefit for patients with metastatic pancreatic cancer.

Circular RNAs and Drug Resistance in Genitourinary Cancers: A Literature Review

In recent years, systematic treatment has made great progress in genitourinary tumors. However, some patients develop resistance to the treatments, resulting in an increase in mortality. Circular RNAs (circRNAs) form a class of non-coding RNAs with high stability and significant clinical relevance. Accumulating evidence indicates that circRNAs play a vital role in cancer development and tumor chemotherapy resistance. This review summarizes the molecular and cellular mechanisms of drug resistance mediated by circRNAs to common drugs used in the treatment of genitourinary tumors. Several circRNAs were identified to regulate the responsiveness to systemic treatments in genitourinary tumors, including chemotherapies such as cisplatin and targeted therapies such as enzalutamide. Canonically, cicrRNAs participate in the competing endogenous RNA (ceRNA) network, or in some cases directly interact with proteins, regulate downstream pathways, and even some circRNAs have the potential to produce proteins or polypeptides. Several cellular mechanisms were involved in circRNA-dependent drug resistance, including autophagy, cancer stem cells, epithelial-mesenchymal transition, and exosomes. The potential clinical prospect of circRNAs in regulating tumor drug resistance was also discussed.

The Role of Ferroptosis Signature in Overall Survival and Chemotherapy of Pancreatic Adenocarcinoma

Studies have shown that ferroptosis, an iron-dependent regulated cell death, is related to prognosis and chemotherapy, but the role of ferroptosis in pancreatic adenocarcinoma (PAAD) is still unclear. We aimed at constructing a ferroptosis-related gene (FRGs) model to predict the PAAD patients' overall survival (OS) and at exploring their values in chemotherapy. We downloaded the mRNA-sequencing data and corresponding clinical data of patients with PAAD from The Cancer Genome Atlas. Lasso-penalized Cox regression analysis was utilized to construct a prognostic risk model, including spermidine/spermine N1-acetyltransferase 1 (SAT1), SAT2, TFRC, SLC39A8, MAP1LC3A, ALOX15, and PROM2. Receiver operating characteristic curves were used to evaluate the prognostic model. International Cancer Genome Consortium cohorts were used to validate this model. Then, we used Genomics of Drug Sensitivity in Cancer and Gene Expression Omnibus databases to analyze the correlation between FRGs and drug sensitivity. Notably, SAT1 showed significant influence in cisplatin and gemcitabine resistance. Finally, in vitro experiments demonstrated that the combination of gemcitabine and cisplatin could induce ferroptosis in AsPC1 cells, probably through elevated SAT1 expression. Taken together, Our 7-gene signature has significant values in predicting the PAAD patients' OS, and it may help inform the clinical treatment of PAAD.

Pancreatic Ductal Adenocarcinoma Cortical Mechanics and Clinical Implications

Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest cancers due to low therapeutic response rates and poor prognoses. Majority of patients present with symptoms post metastatic spread, which contributes to its overall lethality as the 4th leading cause of cancer-related deaths. Therapeutic approaches thus far target only one or two of the cancer specific hallmarks, such as high proliferation rate, apoptotic evasion, or immune evasion. Recent genomic discoveries reveal that genetic heterogeneity, early micrometastases, and an immunosuppressive tumor microenvironment contribute to the inefficacy of current standard treatments and specific molecular-targeted therapies. To effectively combat cancers like PDAC, we need an innovative approach that can simultaneously impact the multiple hallmarks driving cancer progression. Here, we present the mechanical properties generated by the cell’s cortical cytoskeleton, with a spotlight on PDAC, as an ideal therapeutic target that can concurrently attack multiple systems driving cancer. We start with an introduction to cancer cell mechanics and PDAC followed by a compilation of studies connecting the cortical cytoskeleton and mechanical properties to proliferation, metastasis, immune cell interactions, cancer cell stemness, and/or metabolism. We further elaborate on the implications of these findings in disease progression, therapeutic resistance, and clinical relapse. Manipulation of the cancer cell’s mechanical system has already been shown to prevent metastasis in preclinical models, but it has greater potential for target exploration since it is a foundational property of the cell that regulates various oncogenic behaviors.

Gene Therapy Using Nanocarriers for Pancreatic Ductal Adenocarcinoma: Applications and Challenges in Cancer Therapeutics

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers worldwide, and its incidence is increasing. PDAC often shows resistance to several therapeutic modalities and a higher recurrence rate after surgical treatment in the early localized stage. Combination chemotherapy in advanced pancreatic cancer has minimal impact on overall survival. RNA interference (RNAi) is a promising tool for regulating target genes to achieve sequence-specific gene silencing. Here, we summarize RNAi-based therapeutics using nanomedicine-based delivery systems that are currently being tested in clinical trials and are being developed for the treatment of PDAC. Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) genome editing has been widely used for the development of cancer models as a genetic screening tool for the identification and validation of therapeutic targets, as well as for potential cancer therapeutics. This review discusses current advances in CRISPR/Cas9 technology and its application to PDAC research. Continued progress in understanding the PDAC tumor microenvironment and nanomedicine-based gene therapy will improve the clinical outcomes of patients with PDAC.

Aptamers: an emerging navigation tool of therapeutic agents for targeted cancer therapy

Chemotherapeutic agents have been used for the treatment of numerous cancers, but due to poor selectivity and severe systemic side effects, their clinical application is limited. Single-stranded DNA (ssDNA) or RNA aptamers could conjugate with highly toxic chemotherapy drugs, toxins, therapeutic RNAs or other molecules as novel aptamer-drug conjugates (ApDCs), which are capable of significantly improving the therapeutic efficacy and reducing the systemic toxicity of drugs and have great potential in clinics for targeted cancer therapy. In this review, we have comprehensively discussed and summarized the current advances in the screening approaches of aptamers for specific cancer biomarker targeting and development of the aptamer-drug conjugate strategy for targeted drug delivery. Moreover, considering the huge progress in artificial intelligence (AI) for protein and RNA structure predictions, automatic design of aptamers using deep/machine learning techniques could be a powerful approach for rapid and precise construction of biopharmaceutics (i.e., ApDCs) for application in cancer targeted therapy.

Nanomedicine in Pancreatic Cancer: Current Status and Future Opportunities for Overcoming Therapy Resistance

Simple Summary

Despite access to a vast arsenal of anticancer agents, many fail to realise their full therapeutic potential in clinical practice. One key determinant of this is the evolution of multifaceted resistance mechanisms within the tumour that may either pre-exist or develop during the course of therapy. This is particularly evident in pancreatic cancer, where limited responses to treatment underlie dismal survival rates, highlighting the urgent need for new therapeutic approaches. Here, we discuss the major features of pancreatic tumours that contribute to therapy resistance, and how they may be alleviated through exploitation of the mounting and exciting promise of nanomedicines; a unique collection of nanoscale platforms with tunable and multifunctional capabilities that have already elicited a widespread impact on cancer management.

Abstract

The development of drug resistance remains one of the greatest clinical oncology challenges that can radically dampen the prospect of achieving complete and durable tumour control. Efforts to mitigate drug resistance are therefore of utmost importance, and nanotechnology is rapidly emerging for its potential to overcome such issues. Studies have showcased the ability of nanomedicines to bypass drug efflux pumps, counteract immune suppression, serve as radioenhancers, correct metabolic disturbances and elicit numerous other effects that collectively alleviate various mechanisms of tumour resistance. Much of this progress can be attributed to the remarkable benefits that nanoparticles offer as drug delivery vehicles, such as improvements in pharmacokinetics, protection against degradation and spatiotemporally controlled release kinetics. These attributes provide scope for precision targeting of drugs to tumours that can enhance sensitivity to treatment and have formed the basis for the successful clinical translation of multiple nanoformulations to date. In this review, we focus on the longstanding reputation of pancreatic cancer as one of the most difficult-to-treat malignancies where resistance plays a dominant role in therapy failure. We outline the mechanisms that contribute to the treatment-refractory nature of these tumours, and how they may be effectively addressed by harnessing the unique capabilities of nanomedicines. Moreover, we include a brief perspective on the likely future direction of nanotechnology in pancreatic cancer, discussing how efforts to develop multidrug formulations will guide the field further towards a therapeutic solution for these highly intractable tumours.

MiR-489-3p Reduced Pancreatic Cancer Proliferation and Metastasis By Targeting PKM2 and LDHA Involving Glycolysis

Introduction

Malignant proliferation and metastasis are some of the causes of high mortality in pancreatic cancer. MicroRNAs have been a hot spot in cancer research and are involved in tumor formation and metabolic stress responses. However, the biology function and underlying mechanism of miRNA regulating pancreatic cancer progress is remained uncleared.

Methods

RNA-seq analysis the glycolysis associated miRNAs and verified miRNA-489-3p was involving in glycolysis. We used RNA in situ hybridization (ISH) and qRT-PCR to analyze the differential expression of miR-489-3p in pancreatic cancer tissues and adjacent tissues and cell lines. Then the function assay of in vivo and in vitro were used to evaluated the role of miR-489-3p in the proliferation, metastasis and glucose metabolism of pancreatic cancer. Furthermore, dual luciferase reporter and rescue experiments were performed to explore the mechanism underlying in the role of miRNA-489-3p.

Results

We determined that glycolysis associated miRNA miR-489-3p was downregulated in pancreatic cancer tissues and cell lines. The gain and loos of function experiments confirmed that miR-489-3p could inhibit the proliferation, metastasis and glucose metabolism of pancreatic cancer. Further, we found that miR-489-3p could target regulating LDHA and PKM through the luciferase report experiment. Finally, in vivo experiment confirmed that highly expressed miR-489-3p inhibited the growth of pancreatic cancer.

Conclusion

In short, this study identified miR-489-3p as a novel therapy target for pancreatic cancer which was involving in the proliferation, metastasis and glycolysis, but its diagnostic value deserves further study.

Intraperitoneal siRNA Nanoparticles for Augmentation of Gemcitabine Efficacy in the Treatment of Pancreatic Cancer

Pancreatic ductal adenocarcinoma is a deadly disease with limited treatment options due to late diagnosis and resistance to conventional chemotherapy. Among emerging therapeutic targets, the CXCR4 chemokine receptor and polo-like kinase 1 (PLK1) play critical roles in the progression, metastasis, and chemoresistance of pancreatic cancer. Here, we tested the hypothesis that combining CXCR4 inhibition by a polymeric CXCR4 antagonist PAMD-CHOL with PLK1 knockdown by siRNA will enhance the therapeutic effect of gemcitabine (GEM) in the orthotopic model of metastatic pancreatic cancer. We formulated nanoparticles with cholesterol-modified PAMD and siPLK1 and found strong synergism when combined with GEM treatment in vitro in both murine and human pancreatic cancer cell lines. The biodistribution of the nanoparticles in orthotopic pancreatic cancer models revealed strong accumulation in primary and metastatic tumors, with limited hepatic disposition. The cholesterol-containing nanoparticles showed not only increased tumor accumulation than the cholesterol-lacking control but also deeper penetration into the tumors. In a therapeutic study in vivo, the triple combination of PAMD-CHOL/siPLK1 and GEM showed superior anticancer activity when compared with single and dual combination controls. In conclusion, PAMD-CHOL/siPLK1 nanoparticles synergistically enhance anticancer activity of GEM in pancreatic cancer and represent a promising addition to the treatment arsenal.

Role of the microbiome in systemic therapy for pancreatic ductal adenocarcinoma (Review)

A large body of evidence has revealed that the microbiome serves a role in all aspects of cancer, particularly cancer treatment. To date, studies investigating the relationship between the microbiome and systemic therapy for pancreatic ductal adenocarcinoma (PDAC) are lacking. PDAC is a high‑mortality malignancy (5‑year survival rate; <9% for all stages). Systemic therapy is one of the most important treatment choices for all patients; however, resistance or toxicity can affect its efficacy. Studies have supported the hypothesis that the microbiome is closely associated with the response to systemic therapy in PDAC, including the induction of drug resistance, or toxicity and therapy‑related changes in microbiota composition. The present review comprehensively summarized the role of the microbiome in systemic therapy for PDAC and the associated molecular mechanisms in an attempt to provide a novel direction for the improvement of treatment response and proposed potential directions for in‑depth research.

MiR-199 Reverses the Resistance to Gemcitabine in Pancreatic Cancer by Suppressing Stemness through Regulating the Epithelial-Mesenchymal Transition

PURPOSE

the present study aims to investigate the function of miR-199 on gemcitabine (GEM)-resistance in pancreatic cancer, as well as the underlying mechanism.

METHODS

the GEM-resistant SW1990 cell line (SW1990/SZ) was established. The CCK-8 assay was used to detect the cell viability. The self-renewal of SW1990/SZ cells was evaluated by sphere formation and the colony formation assay. The apoptosis was detected by flow cytometry and the migration ability was measured by the transwell assay. The dual-luciferase gene reporter assay was utilized to confirm the binding between miR-199 and Snail. The expression level of CD44, ALDH1, Nanog, E-cadherin, Vimentin, β-catenin, and Snail was determined by the Western blotting assay.

RESULTS

the cell sphere formation rate, number of spheres, and expression level of CD44, ALDH1, and Nanog in GEM-treated SW1990/SZ cells were significantly suppressed by miR-199, accompanied by declined proliferation ability, an increased apoptotic rate, inhibited migration ability, and suppressed EMT progression. The binding site between miR-199 and 3'-UTR of Snail was predicted and confirmed. The inhibitory effect of miR-199 on self-renewal of SW1990/GZ cells and the faciliating property of miR-199 on the inhibitory effect of GEM against the proliferation ability, migration ability, and EMT progression were abolished by overexpressing Snail.

CONCLUSION

MiR-199 reversed the resistance to GEM in pancreatic cancer by suppressing stemness through regulating the EMT.

Epigenetic activation of the elongator complex sensitizes gallbladder cancer to gemcitabine therapy

Background

Gallbladder cancer (GBC) is known for its high malignancy and multidrug resistance. Previously, we uncovered that impaired integrity and stability of the elongator complex leads to GBC chemotherapy resistance, but whether its restoration can be an efficient therapeutic strategy for GBC remains unknown.

Methods

RT-qPCR, MS-qPCR and ChIP-qPCR were used to evaluate the direct association between ELP5 transcription and DNA methylation in tumour and non-tumour tissues of GBC. EMSA, chromatin accessibility assays, and luciferase assays were utilized to analysis the DNA methylation in interfering PAX5-DNA interactions. The functional experiments in vitro and in vivo were performed to investigate the effects of DNA demethylating agent decitabine (DAC) on the transcription activation of elongator complex and the enhanced sensitivity of gemcitabine in GBC cells. Tissue microarray contains GBC tumour tissues was used to evaluate the association between the expression of ELP5, DNMT3A and PAX5.

Results

We demonstrated that transcriptional repression of ELP5 in GBC was highly correlated with hypermethylation of the promoter. Mechanistically, epigenetic analysis revealed that DNA methyltransferase DNMT3A-catalysed hypermethylation blocked transcription factor PAX5 activation of ELP5 by disrupting PAX5-DNA interaction, resulting in repressed ELP5 transcription. Pharmacologically, the DNA demethylating agent DAC eliminated the hypermethylated CpG dinucleotides in the ELP5 promoter and then facilitated PAX5 binding and reactivated ELP5 transcription, leading to the enhanced function of the elongator complex. To target this mechanism, we employed a sequential combination therapy of DAC and gemcitabine to sensitize GBC cells to gemcitabine-therapy through epigenetic activation of the elongator complex.

Conclusions

Our findings suggest that ELP5 expression in GBC is controlled by DNA methylation-sensitive induction of PAX5. The sequential combination therapy of DAC and gemcitabine could be an efficient therapeutic strategy to overcome chemotherapy resistance in GBC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02186-0.

OXCT1 Enhances Gemcitabine Resistance Through NF-κB Pathway in Pancreatic Ductal Adenocarcinoma

Background

Pancreatic ductal adenocarcinoma (PDAC) is a type of malignant tumor with a five-year survival rate of less than 10%. Gemcitabine (GEM) is the most commonly used drug for PDAC chemotherapy. However, a vast majority of patients with PDAC develop resistance after GEM treatment.

Methods

We screened for GEM resistance genes through bioinformatics analysis. We used immunohistochemistry to analyze 3-oxoacid CoA-transferase 1 (OXCT1) expression in PDAC tissues. The survival data were analyzed using the Kaplan–Meier curve. The expression levels of the genes related to OXCT1 and the NF-κB signaling pathway were quantified using real−time quantitative PCR and western blot analyses. We performed flow cytometry to detect the apoptosis rate. Colony formation assay was performed to measure the cell proliferation levels. The cytotoxicity assays of cells were conducted using RTCA. The downstream pathway of OXCT1 was identified via the Gene Set Enrichment Analysis. Tumor growth response to GEM in vivo was also determined in mouse models.

Results

Bioinformatics analysis revealed that OXCT1 is the key gene leading to GEM resistance. Patients with high OXCT1 expression exhibited short relapse-free survival under GEM treatment. OXCT1 overexpression in PDAC cell lines exerted inhibitory effect on apoptosis after GEM treatment. However, the down-regulation of OXCT1 showed the opposite effect. Blocking the NF-κB signaling pathway also reduced GEM resistance of PDAC cells. Tumor growth inhibition induced by GEM in vivo reduced after OXCT1 overexpression. Moreover, the effect of OXCT1 on GEM refractoriness in PDAC cell lines was reversed through using an NF-κB inhibitor.

Conclusion

OXCT1 promoted GEM resistance in PDAC via the NF-κB signaling pathway both in vivo and in vitro. Our results suggest that OXCT1 could be used as a potential therapeutic target for patients with PDAC.

One-shot dual gene editing for drug-resistant pancreatic cancer therapy

It is challenging to diagnose patients with pancreatic ductal adenocarcinoma (PDAC) early on, and their treatment is often complex. Gemcitabine (GEM) is the first-line treatment for PDAC, but its efficacy is limited in most patients due to the GEM resistance from KRAS and P53 gene mutations. We describe the correction of a double gene mutation and therapeutic effect for the GEM resistant PDAC. Bio-available nanoliposomes (NL) possessing Cas9-ribonucleoproteins and adenine-base editors were developed to conduct KRAS and P53 mutation gene editing directly. NLs were conjugated with EGFR antibodies to tumor-specific delivery, and the anti-cancer effect was verified in vitro and in vivo Model. Our GEM-combinatorial therapeutic strategies using double gene editing systems with one-shot may be a potent therapy for PDAC, overcoming chemoresistance.

LncRNA HIF1A-AS1 Promotes Gemcitabine Resistance of Pancreatic Cancer by Enhancing Glycolysis through Modulating the AKT/YB1/HIF1α Pathway

Gemcitabine (GEM) resistance is a major challenge for chemotherapy of pancreatic cancer. Previous studies have reported on the role of long noncoding RNA (lncRNA) in tumorigenesis of pancreatic cancer, however, the involvement of lncRNA in the development of GEM resistance of pancreatic cancer remains unclear. In the present study, we demonstrated that the antisense RNA1 of HIF1α (HIF1A-AS1) was significantly elevated in the GEM-resistant pancreatic cancer cells. Gain- and lost-of-function experiments validated that HIF1A-AS1 promoted GEM resistance of pancreatic cancer cells both in vitro and vivo. We further revealed that HIF1A-AS1 upregulated HIF1α expression and thus promoted glycolysis to enhance GEM resistance of pancreatic cancer cells. Mechanistically, HIF1A-AS1 facilitated the interaction between serine/threonine kinase AKT and Y-box-binding protein 1 (YB1), which promoted phosphorylation of YB1 (pYB1). Meanwhile, HIF1A-AS1 recruited pYB1 to HIF1α mRNA that consequently promoted translation of HIF1α. Furthermore, HIF1α promoted HIF1A-AS1 transcription by directly binding to the HIF1α response element in the promoter area of HIF1A-AS1 to form a positive feedback. Consistently, both HIF1A-AS1 and HIF1α were upregulated in pancreatic cancer tissues and associated with poor overall survival. Together, our results underline a reciprocal loop of HIF1A-AS1 and HIF1α that contributes to GEM resistance of pancreatic cancer and indicate that HIF1A-AS1 might serve as a novel therapeutic target for GEM resistance of pancreatic cancer. SIGNIFICANCE: These findings show that a reciprocal feedback of HIF1A-AS1 and HIF1α promotes gemcitabine resistance of pancreatic cancer, which provides an applicable therapeutic target.

MicroRNAs in Pancreatic Cancer and Chemoresistance

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading malignancies affecting human health, largely because of the development of resistance to chemotherapy/radiotherapy. There are many mechanisms that mediate the development of drug resistance, such as the transport of antineoplastic agents into cells, shifts in energy metabolism and environment, antineoplastic agent-induced DNA damage, and genetic mutations. MicroRNAs are short, noncoding RNAs that are 20 to 24 nucleotides in length and serve several biological functions. They bind to the 3'-untranslated regions of target genes and induce target degradation or translational inhibition. MicroRNAs can regulate several target genes and mediate PDAC chemotherapy/radiotherapy resistance. The detection of novel microRNAs would not only reveal the molecular mechanisms of PDAC and resistance to chemotherapy/radiotherapy but also provide new approaches to PDAC therapy. MicroRNAs are thus potential therapeutic targets for PDAC and might be essential in uncovering new mechanisms of the disease.

CD95L Inhibition Impacts Gemcitabine-Mediated Effects and Non-Apoptotic Signaling of TNF-α and TRAIL in Pancreatic Tumor Cells

Despite the potential apoptotic functions, the CD95/CD95L system can stimulate survival as well as pro-inflammatory signaling, particularly through the activation of NFκB. This holds true for the TNF/TNFR and the TRAIL/TRAILR systems. Thus, signaling pathways of these three death ligands converge, yet the specific impact of the CD95/CD95L system in this crosstalk has not been well studied. In this study, we show that gemcitabine stimulates the expression of pro-inflammatory cytokines, such as IL6 and IL8, under the influence of the CD95/CD95L system and the pharmacological inhibitor, sCD95Fc, substantially reduced the expression in two PDAC cell lines, PancTuI-luc and A818-4. The stem cell phenotype was reduced when induced upon gemcitabine as well by sCD95Fc. Moreover, TNF-α as well as TRAIL up-regulate the expression of CD95 and CD95L in both cell lines. Conversely, we detected a significant inhibitory effect of sCD95Fc on the expression of both IL8 and IL6 induced upon TNF-α and TRAIL stimulation. In vivo, CD95L inhibition reduced xeno-transplanted recurrent PDAC growth. Thus, our findings indicate that inhibition of CD95 signaling altered the chemotherapeutic effects of gemcitabine, not only by suppressing the pro-inflammatory responses that arose from the CD95L-positive tumor cells but also from the TNF-α and TRAIL signaling in a bi-lateral crosstalk manner.

Ferroptosis: At the Crossroad of Gemcitabine Resistance and Tumorigenesis in Pancreatic Cancer

The overall five-year survival rate of pancreatic cancer has hardly changed in the past few decades (less than 10%) because of resistance to all known therapies, including chemotherapeutic drugs. In the past few decades, gemcitabine has been at the forefront of treatment for pancreatic ductal adenocarcinoma, but more strategies to combat drug resistance need to be explored. One promising possibility is ferroptosis, a form of a nonapoptotic cell death that depends on intracellular iron and occurs through the accumulation of lipid reactive oxygen species, which are significant in drug resistance. In this article, we reviewed gemcitabine-resistance mechanisms; assessed the relationship among ferroptosis, tumorigenesis and gemcitabine resistance, and explored a new treatment method for pancreatic cancer.

Enhancement of gemcitabine efficacy by K73-03 via epigenetically regulation of miR-421/SPINK1 in gemcitabine resistant pancreatic cancer cells

BACKGROUND

Gemcitabine (GCB) is a first-line chemotherapeutic drug for pancreatic cancer (PCa). However, the resistance begins developing within weeks of chemotherapy. SPINK1 overexpression enhances resistance to chemotherapy. In a recent study, our laboratory established that the oleanolic acid (OA) derivative, K73-03, had a strong inhibitory effect on a SPINK1 overexpressed PCa cells.

PURPOSE

In our current study, we studied the enhancement of GCB inhibitory effect by K73-03, a new novel OA derivative, alone or in combination with GCB on the GCB-resistant PCa cells by mitochondrial damage through regulation of the miR-421/SPINK1.

METHODS

We detected the binding between miR-421 and SPINK1-3'-UTR in GCB-resistant PCa cells using Luciferase reporter assays. Cells viability, apoptosis, migration, and mitochondrial damage were investigated.

RESULTS

The results demonstrated that the combination of K73-03 and GCB suppressed the growth of AsPC-1 and MIA PaCa-2 cells synergistically, with or without GCB resistance. Mechanistic findings showed that a combination of K73-03 and GCB silences SPINK1 epigenetically by miR-421 up-regulating, which leads to mitochondrial damage and inducing apoptosis in GCB-resistant PCa cells.

CONCLUSION

We found an interesting finding that the 73-03 in combination with GCB can improve GCB efficacy and decrease PCa resistance, which induced apoptosis and mitochondrial damage through epigenetic inhibition of SPINK1 transcription by miR-421 up-regulation. This was the first study that used OA derivatives on GCB-resistant PCa cells, so this combined strategy warrants further investigation.

Epithelial-to-Mesenchymal Transition Is Not a Major Modulating Factor in the Cytotoxic Response to Natural Products in Cancer Cell Lines

Numerous natural products exhibit antiproliferative activity against cancer cells by modulating various biological pathways. In this study, we investigated the potential use of eight natural compounds (apigenin, curcumin, epigallocatechin gallate, fisetin, forskolin, procyanidin B2, resveratrol, urolithin A) and two repurposed agents (fulvestrant and metformin) as chemotherapy enhancers and mesenchymal-to-epithelial (MET) inducers of cancer cells. Screening of these compounds in various colon, breast, and pancreatic cancer cell lines revealed anti-cancer activity for all compounds, with curcumin being the most effective among these in all cell lines. Although some of the natural products were able to induce MET in some cancer cell lines, the MET induction was not related to increased synergy with either 5-FU, irinotecan, gemcitabine, or gefitinib. When synergy was observed, for example with curcumin and irinotecan, this was unrelated to MET induction, as assessed by changes in E-cadherin and vimentin expression. Our results show that MET induction is compound and cell line specific, and that MET is not necessarily related to enhanced chemosensitivity.

Histone acetyltransferase 1 promotes gemcitabine resistance by regulating the PVT1/EZH2 complex in pancreatic cancer

The poor prognosis of pancreatic cancer is primarily due to the development of resistance to therapies, including gemcitabine. The long noncoding RNA PVT1 (lncRNA PVT1) has been shown to interact with enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2), promoting gemcitabine resistance in pancreatic cancer. In this study, we found histone acetyltransferase 1 (HAT1) enhanced the tolerance of pancreatic cancer cells to gemcitabine and HAT1-mediated resistance mechanisms were regulated by PVT1 and EZH2. Our results showed that the aberrant HAT1 expression promoted gemcitabine resistance, while silencing HAT1 restored gemcitabine sensitivity. Moreover, HAT1 depletion caused a notable increase of gemcitabine sensitivity in gemcitabine-resistant pancreatic cancer cell lines. Further research found that HAT1 increased PVT1 expression to induce gemcitabine resistance, which enhanced the binding of bromodomain containing 4 (BRD4) to the PVT1 promoter, thereby promoting PVT1 transcription. Besides, HAT1 prevented EZH2 degradation by interfering with ubiquitin protein ligase E3 component n-recognin 4 (UBR4) binding to the N-terminal domain of EZH2, thus maintaining EZH2 protein stability to elevate the level of EZH2 protein, which also promoted HAT1-mediated gemcitabine resistance. These results suggested that HAT1 induced gemcitabine resistance of pancreatic cancer cells through regulating PVT1/EZH2 complex. Given this, Chitosan (CS)-tripolyphosphate (TPP)-siHAT1 nanoparticles were developed to block HAT1 expression and improve the antitumor effect of gemcitabine. The results showed that CS-TPP-siHAT1 nanoparticles augmented the antitumor effects of gemcitabine in vitro and in vivo. In conclusion, HAT1-targeted therapy can improve observably gemcitabine sensitivity of pancreatic cancer cells. HAT1 is a promising therapeutic target for pancreatic cancer.

Gemcitabine synergizes with cisplatin to inhibit nasopharyngeal carcinoma cell proliferation and tumor growth

In a recently published phase III clinical trial, gemcitabine (GEM) plus cisplatin (DDP) induction chemotherapy significantly improved recurrence-free survival and overall survival and became the standard of care among patients with locoregionally advanced NPC. However, the molecular mechanisms of GEM synergized with DPP in NPC cells remain elucidated. These findings prompt us to explore the effect of the combination between GEM and DDP in NPC cell lines through proliferative phenotype, immunofluorescence, flow cytometry, and western blotting assays. In vitro studies reveal that GEM or DPP treated alone induces cell cycle arrest, promotes cell apoptosis, forces DNA damage response, and GEM synergism with DDP significantly increases the above effects in NPC cells. In vivo studies indicate that GEM or DPP treated alone significantly inhibits the tumor growth and prolongs the survival time of mice injected with SUNE1 cells compared to the control group. Moreover, the mice treated with GEM combined with DDP have smaller tumors and survive longer than those in GEM or DPP treated alone group. In addition, P-gp may be the key molecule that regulates the synergistic effect of gemcitabine and cisplatin. GEM synergizes with DPP to inhibit NPC cell proliferation and tumor growth by inducing cell cycle arrest, cell apoptosis, and DNA damage response, which reveals the mechanisms of combined GEM and DDP induction chemotherapy in improving locoregionally advanced NPC.

Crosstalk between Environmental Inflammatory Stimuli and Non-Coding RNA in Cancer Occurrence and Development

Simple Summary

Increasing evidence has indicated that chronic inflammatory processes have an influence on tumor occurrence and all stages of tumor development. A dramatic increase of studies into non-coding RNAs (ncRNAs) biology has shown that ncRNAs act as oncogenic drivers and tumor suppressors in various inflammation-induced cancers. Thus, this complex network of inflammation-associated cancers and ncRNAs offers targets for prevention from the malignant transformation from inflammation and treatment of malignant diseases.

Abstract

There is a clear relationship between inflammatory response and different stages of tumor development. Common inflammation-related carcinogens include viruses, bacteria, and environmental mutagens, such as air pollutants, toxic metals, and ultraviolet light. The expression pattern of ncRNA changes in a variety of disease conditions, including inflammation and cancer. Non-coding RNAs (ncRNAs) have a causative role in enhancing inflammatory stimulation and evading immune responses, which are particularly important in persistent pathogen infection and inflammation-to-cancer transformation. In this review, we investigated the mechanism of ncRNA expression imbalance in inflammation-related cancers. A better understanding of the function of inflammation-associated ncRNAs may help to reveal the potential of ncRNAs as a new therapeutic strategy.

Repositioning of duloxetine to target pancreatic stellate cells

Pancreatic cancer cells (PCCs) are surrounded by an abundant stroma, which is produced by pancreatic stellate cells (PSCs). PSCs promote tumor cell proliferation and invasion. The objective of the current study was to identify compounds that suppress PSC activation. Gene expression profiles of cancer-derived fibroblasts and normal fibroblasts were used, and the pathway analysis suggested altered pathways that were chosen for validation. It was found that the ‘neuroactive ligand-receptor interaction’ pathway from the Kyoto Encyclopedia of Genes and Genomes pathway analysis was one of the altered pathways. Several compounds related with this pathway were chosen, and changes in PSC activity were investigated using fluorescence staining of lipid droplets, reverse transcription-quantitative PCR, western blotting, and invasion and migration assays. Among these candidates, duloxetine, a serotonin-noradrenaline reuptake inhibitor, was found to suppress PSC activation and disrupt tumor-stromal interaction. Thus, duloxetine may be a potential drug for suppressing PSC activation and pancreatic cancer growth.

The enhancement of Tetrandrine to gemcitabine-resistant PANC-1 cytochemical sensitivity involves the promotion of PI3K/Akt/mTOR-mediated apoptosis and AMPK-regulated autophagy

BACKGROUND

In the process of tumor development, the resistance of pancreatic cancer cells to gemcitabine (GEM) is mainly due to the suppression and dysregulation of apoptosis signals to a large extent. Therefore, it is very necessary to develop pro-apoptotic drugs for combined treatment of pancreatic cancer to increase the activity of GEM and improve the prognosis of pancreatic cancer.

METHODS AND RESULTS

GEM-resistant PANC-1 cells were treated with increasing doses of GEM. The effects of GEM and TET on apoptosis were evaluated by flow cytometry and Hoechst 33258 staining. We also evaluated the expression of survivin by real-time PCR, and the expression levels of proteins involved in apoptosis, autophagy, and PI3K/Akt/mTOR signaling were detected by western blotting. The results showed that TET downregulated expression of survivin by inhibiting the PI3K/Akt/mTOR signaling pathway to promote pancreatic cancer cell apoptosis, thereby enhancing pancreatic cancer cell sensitivity to GEM. Moreover, TET enhanced cytotoxic and autophagy-dependent cell death by upregulating the AMPK-autophagy axis, and this effect was reversed by inhibition of AMPK.

CONCLUSIONS

TET promotes apoptosis by inhibiting the PI3K/Akt/mTOR signaling pathway and promotes autophagy via up-regulating the AMPK signaling pathway to play an anti-tumor effect in GEM-resistant pancreatic cancer cells, which represents a new therapeutic strategy for the treatment of GEM-resistant pancreatic cancer.

GSK3β as a novel promising target to overcome chemoresistance in pancreatic cancer

Pancreatic cancer is an aggressive malignancy with increasing incidence and poor prognosis due to its late diagnosis and intrinsic chemoresistance. Most pancreatic cancer patients present with locally advanced or metastatic disease characterized by inherent resistance to chemotherapy. These features pose a series of therapeutic challenges and new targets are urgently needed. Glycogen synthase kinase 3 beta (GSK3β) is a conserved serine/threonine kinase, which regulates key cellular processes including cell proliferation, DNA repair, cell cycle progression, signaling and metabolic pathways. GSK3β is implicated in non-malignant and malignant diseases including inflammation, neurodegenerative diseases, diabetes and cancer. GSK3β recently emerged among the key factors involved in the onset and progression of pancreatic cancer, as well as in the acquisition of chemoresistance. Intensive research has been conducted on key oncogenic functions of GSK3β and its potential as a druggable target; currently developed GSK3β inhibitors display promising results in preclinical models of distinct tumor types, including pancreatic cancer. Here, we review the latest findings about GSK-3β biology and its role in the development and progression of pancreatic cancer. Moreover, we discuss therapeutic agents targeting GSK3β that could be administered as monotherapy or in combination with other drugs to surmount chemoresistance. Several studies are also defining potential gene signatures to identify patients who might benefit from GSK3β-based therapeutic intervention. This detailed overview emphasizes the urgent need of additional molecular studies on the impact of GSK3β inhibition as well as structural analysis of novel compounds and omics studies of predictive biomarkers.

Microorganisms in chemotherapy for pancreatic cancer: An overview of current research and future directions

Pancreatic cancer is a malignant tumor of the digestive system with a very high mortality rate. While gemcitabine-based chemotherapy is the predominant treatment for terminal pancreatic cancer, its therapeutic effect is not satisfactory. Recently, many studies have found that microorganisms not only play a consequential role in the occurrence and progression of pancreatic cancer but also modulate the effect of chemotherapy to some extent. Moreover, microorganisms may become an important biomarker for predicting pancreatic carcinogenesis and detecting the prognosis of pancreatic cancer. However, the existing experimental literature is not sufficient or convincing. Therefore, further exploration and experiments are imperative to understanding the mechanism underlying the interaction between microorganisms and pancreatic cancer. In this review, we primarily summarize and discuss the influences of oncolytic viruses and bacteria on pancreatic cancer chemotherapy because these are the two types of microorganisms that are most often studied. We focus on some potential methods specific to these two types of microorganisms that can be used to improve the efficacy of chemotherapy in pancreatic cancer therapy.

The role of FOLFIRINOX in metastatic pancreatic cancer: a meta-analysis

Background

The prognosis of pancreatic cancer (PC) is extremely poor, and most patients with metastatic PC still receive palliative care. Here, we report the efficacy and safety of FOLFIRINOX (oxaliplatin, irinotecan, leucovorin, 5-fluorouracil) in the treatment of metastatic PC.

Methods

We searched PubMed, Web of Science, EBSCO, and Cochrane library databases for articles that described efficacy and safety of FOLFIRINOX in patients with metastatic PC, from January 1996 to July 2020. The primary outcomes targeted included overall survival (OS) and progression-free survival (PFS).

Results

We found that FOLFIRINOX could directly improve OS rate of patients with metastatic PC (HR 0.76, 95% Cl 0.67–0.86, p<0.001) but had no benefit on PFS. Results from subgroup analyses showed that FOLFIRINOX had superior benefits than monochemotherapy (HR 0.59, 95% Cl 0.52–0.67, p<0.001), followed by FOLFIRINOX versus combination chemotherapy (HR 0.76, 95% Cl 0.61–0.95, p<0.001). The result of FOLFIRINOX versus nab-paclitaxel + gemcitabine had no benefit (HR 0.91, 95% Cl 0.82–1.02, p>0.05). The main adverse events (AEs) targeted hematological toxicity and the gastrointestinal system, and included febrile neutropenia, a reduction in white blood cells and appetite, as well as diarrhea.

Conclusion

These findings indicated that FOLFIRINOX has potential benefits for the prognosis of patients with metastatic PC. Furthermore, there is no difference between the regimen of FOLFIRINOX and nab-paclitaxel + gemcitabine in this study. The application of FOLFIRINOX should be according to the actual situation of the patients and the experience of the doctors.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02291-6.

Synergistic Pharmacodynamic Effects of Gemcitabine and Fibroblast Growth Factor Receptor Inhibitors on Pancreatic Cancer Cell Cycle Kinetics and Proliferation

Median survival of pancreatic ductal adenocarcinoma cancer (PDAC) is 6 months, with 9% 5-year survival. Standard-of-care gemcitabine (Gem) provides only modest survival benefits, and combination therapies integrating novel targeted agents could improve outcomes. Fibroblast growth factor (FGF) receptors (FGFRs) play important roles in PDAC growth and invasion. Therefore, FGFR inhibitors (FGFRi) merit further investigation. Efficacy of Gem combined with NVP-BGJ398, a pan-FGFRi, was investigated in multiple PDAC cell lines exposed to the drugs alone and combined. Cell cycle distribution and cell numbers were quantified over time. Two pharmacodynamic models were developed to investigate Gem/BGJ398 interactions quantitatively: a drug-mediated cell proliferation/death model, and a drug-perturbed cell cycle progression model. The models captured temporal changes in cell numbers, cell cycle progression, and cell death during drug exposure. Simultaneous fitting of all data provided reasonable parameter estimates. Therapeutic efficacy was then evaluated in a PDAC mouse model. Compared with Gem alone, combined Gem + FGFRi significantly downregulated ribonucleotide-diphosphate reductase large subunit 1 (RRM1), a gemcitabine resistance (GemR) biomarker, suggesting the FGFRi inhibited GemR emergence. The cell proliferation/death pharmacodynamic model estimated the drug interaction coefficient ψ death = 0.798, suggesting synergistic effects. The mechanism-based cell cycle progression model estimated drug interaction coefficient ψ cycle = 0.647, also suggesting synergy. Thus, FGFR inhibition appears to synergize with Gem in PDAC cells and tumors by sensitizing cells to Gem-mediated inhibition of proliferation and cell cycle progression. SIGNIFICANCE STATEMENT: An integrated approach of quantitative modeling and experimentation was employed to investigate the nature of fibroblast growth factor receptor inhibitor (FGFRi)/gemcitabine (Gem) interaction, and to identify mechanisms by which FGFRi exposure reverses Gem resistance in pancreatic cancer cells. The results show that FGFRi interacts synergistically with Gem to sensitize pancreatic cancer cells and tumors to Gem-mediated inhibition of proliferation and cell cycle progression. Thus, addition of FGFRi to standard-of-care Gem treatment could be a clinically deployable approach to enhance therapeutic benefit to pancreatic cancer patients.

A redox probe screens MTHFD1 as a determinant of gemcitabine chemoresistance in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a type of solid tumor derived from the bile duct epithelium that features universal gemcitabine resistance. Here, we utilized a gene-encoded ROS biosensor probe (HyPer3 probe) to sort subpopulations with different redox statuses from CCA cells. The isolated HyPer-low subpopulation CCA cells, which exhibited relatively lower cellular ROS levels, exhibited higher chemoresistance to gemcitabine than HyPer-high subpopulation CCA cells in vitro and in vivo. Mechanistically, increased expression of MTHFD1 was found in HyPer-low cells. Knocking down MTHFD1 in HyPer-low cells enhanced cellular ROS and restored sensitivity to gemcitabine. Furthermore, the MTHFD1 inhibitor antifolate compound methotrexate (MTX) increased cellular ROS, and combining gemcitabine with MTX effectively suppressed cholangiocarcinoma cell growth. In summary, the MTHFD1 level mediated the heterogeneous cellular redox status in CCA, which resulted in chemoresistance to gemcitabine. Our data suggest a novel strategy for CCA chemotherapy.

Zebularine suppressed gemcitabine-induced senescence and improved the cellular and plasma pharmacokinetics of gemcitabine, augmented by liposomal co-delivery

Chemoresistance is a major factor driving cancer recurrence. This study investigated the potential of zebularine, a dual cytidine deaminase (CDA)/epigenetic inhibitor, to circumvent gemcitabine-resistance in pancreatic cancer using a nanomedicine co-delivery approach. The mRNA expression of key metabolic enzymes, including CDA for gemcitabine deactivation in a gemcitabine-resistant cell line Gr2000 and its parental MIA PaCa-2 was compared using quantitative reverse transcription polymerase chain reaction. A highly gemcitabine-resistant population (HRP) in Gr2000 were characterised for their growth pattern, β-galactosidase activity (a hallmark of senescence) and chemosensitivity to zebularine after isolation. The CDA inhibition effects of zebularine on the intracellular gemcitabine accumulation and pharmacokinetics in rats when co-delivered with pH-sensitive liposomes (pSL) were investigated. Gr2000 had a 3-time upregulated mRNA expression and enzyme activity for CDA. The HRP (28% of bulk Gr2000) were predominately senescent cells which re-proliferated following a growth arrest for a week. Zebularine suppressed the regrowth of senescent cells, meanwhile enhanced cellular gemcitabine concentration by 2-fold. When co-delivered with pSL, zebularine increased cellular gemcitabine concentration by 4-fold, and extended the half-life of gemcitabine in plasma by 22-fold in rats. In conclusion, multiple mechanisms including therapy-induced senescence were identified with gemcitabine-resistance. Co-delivery of zebularine using liposomes could provide multifaceted benefits in gemcitabine therapy for pancreatic cancer treatment.

LAMC2 promotes cancer progression and gemcitabine resistance through modulation of EMT and ATP-binding cassette transporters in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with poor prognosis. Gemcitabine remains an effective option for the majority of PDAC patients. Unfortunately, currently no reliable prognostic and predictive biomarkers of therapeutic response are available for the patients with PDAC. Laminin γ2 (LAMC2) is overexpressed in several cancers, and its high expression facilitates cancer development and chemoresistance. However, its functional role in PDAC remains unclear, and a better understanding of this will likely help improve the prognosis of PDAC patients. This study aimed to elucidate the clinical and biological role of LAMC2 in PDAC. We first analyzed the expression levels of LAMC2 by real-time reverse transcription PCR in a cohort of 114 PDAC patients. Interestingly, higher expression of LAMC2 significantly correlated with poor survival in PDAC cohort. In addition, elevated LAMC2 expression served as a potential prognostic marker for survival. Subsequently, functional characterization for the role of LAMC2 in PDAC was performed by small interfering RNA knockdown in pancreatic cancer (PC) cell lines. Interestingly, inhibition of LAMC2 in PC cells enhanced the gemcitabine sensitivity and induction of apoptosis. Moreover, it inhibited colony formation ability, migration and invasion potential. Furthermore, LAMC2 regulated the expression of epithelial-mesenchymal transition (EMT) phenotype. In addition, LAMC2 significantly correlated with genes associated with the expression of ATP-binding cassette (ABC) transporters in PC cells and PDAC patients. In conclusion, these results suggest that LAMC2 regulates gemcitabine sensitivity through EMT and ABC transporters in PDAC and may be a novel therapeutic target in PDAC patients.