ERK-mediated transcriptional activation of Dicer is involved in gemcitabine resistance of pancreatic cancer

Vilazodone Alleviates Neurogenesis-Induced Anxiety in the Chronic Unpredictable Mild Stress Female Rat Model: Role of Wnt/β-Catenin Signaling

Defective β-catenin signaling is accompanied with compensatory neurogenesis process that may pave to anxiety. β-Catenin has a distinct role in alleviating anxiety in adolescence; however, it undergoes degradation by the degradation complex Axin and APC. Vilazodone (VZ) is a fast, effective antidepressant with SSRI activity and 5-HT1A partial agonism that amends somatic and/or psychic symptoms of anxiety. Yet, there is no data about anxiolytic effect of VZ on anxiety-related neurogenesis provoked by stress-reduced β-catenin signaling. Furthermore, females have specific susceptibility toward psychopathology. The aim of the present study is to uncover the molecular mechanism of VZ relative to Wnt/β-catenin signaling in female rats. Stress-induced anxiety was conducted by subjecting the rats to different stressful stimuli for 21 days. On the 15th day, stressed rats were treated with VZ(10 mg/kg, p.o.) alone or concomitant with the Wnt inhibitor: XAV939 (0.1 mg/kg, i.p.). Anxious rats showed low β-catenin level turned over by Axin-1 with unanticipated reduction of APC pursued with elevated protein levels of neurogenesis-stimulating proteins: c-Myc and pThr183-Erk likewise gene expressions of miR-17-5p and miR-18. Two weeks of VZ treatment showed anxiolytic effect figured by alleviation of hippocampal histological examination. VZ protected β-catenin signal via reduction in Axin-1 and elevation of APC conjugated with modulation of β-catenin downstream targets. The cytoplasmic β-catenin turnover by Axin-1 was restored by XAV939. Herein, VZ showed anti-anxiety effect, which may be in part through regaining the balance of the reduced β-catenin and its subsequent exaggerated response of p-Erk, c-Myc, Dicer-1, miR-17-5p, and miR-18.

Silencing of Dicer enhances dacarbazine resistance in melanoma cells by inhibiting ADSL expression

Dacarbazine (DTIC) is the primary first-line treatment for advanced-stage metastatic melanoma; thus, DTIC resistance is poses a major challenge. Therefore, investigating the mechanism underlying DTIC resistance must be investigated. Dicer, a type III cytoplasmic endoribonuclease, plays a pivotal role in the maturation of miRNAs. Aberrant Dicer expression may contribute to tumor progression, clinical aggressiveness, and poor prognosis in various tumors. Dicer inhibition led to a reduction in DTIC sensitivity and an augmentation in stemness in melanoma cells. Clinical analyses indicated a low Dicer expression level as a predictor of poor prognosis factor. Metabolic alterations in tumor cells may interfere with drug response. Adenylosuccinate lyase (ADSL) is a crucial enzyme in the purine metabolism pathway. An imbalance in ADSL may interfere with the therapeutic efficacy of drugs. We discovered that DTIC treatment enhanced ADSL expression and that Dicer silencing significantly reduced ADSL expression in melanoma cells. Furthermore, ADSL overexpression reversed Dicer silencing induced DTIC resistance and cancer stemness. These findings indicate that Dicer-mediated ADSL regulation influences DTIC sensitivity and stemness in melanoma cells.

The Link between Diabetes, Pancreatic Tumors, and miRNAs-New Players for Diagnosis and Therapy?

Despite significant progress in medicine, pancreatic cancer is one of the most tardily diagnosed cancer and is consequently associated with a poor prognosis and a low survival rate. The asymptomatic clinical picture and the lack of relevant diagnostic markers for the early stages of pancreatic cancer are believed to be the major constraints behind an accurate diagnosis of this disease. Furthermore, underlying mechanisms of pancreatic cancer development are still poorly recognized. It is well accepted that diabetes increases the risk of pancreatic cancer development, however the precise mechanisms are weakly investigated. Recent studies are focused on microRNAs as a causative factor of pancreatic cancer. This review aims to provide an overview of the current knowledge of pancreatic cancer and diabetes-associated microRNAs, and their potential in diagnosis and therapy. miR-96, miR-124, miR-21, and miR-10a were identified as promising biomarkers for early pancreatic cancer prediction. miR-26a, miR-101, and miR-200b carry therapeutic potential, as they not only regulate significant biological pathways, including the TGF-β and PI3K/AKT, but their re-expression contributes to the improvement of the prognosis by reducing invasiveness or chemoresistance. In diabetes, there are also changes in the expression of microRNAs, such as in miR-145, miR-29c, and miR-143. These microRNAs are involved, among others, in insulin signaling, including IRS-1 and AKT (miR-145), glucose homeostasis (hsa-miR-21), and glucose reuptake and gluconeogenesis (miR-29c). Although, changes in the expression of the same microRNAs are observed in both pancreatic cancer and diabetes, they exert different molecular effects. For example, miR-181a is upregulated in both pancreatic cancer and diabetes mellitus, but in diabetes it contributes to insulin resistance, whereas in pancreatic cancer it promotes tumor cell migration, respectively. To conclude, dysregulated microRNAs in diabetes affect crucial cellular processes that are involved in pancreatic cancer development and progression.

KRAS Hijacks the miRNA Regulatory Pathway in Cancer

Extensive studies have focused on the misregulation of individual miRNAs in cancer. More recently, mutations in the miRNA biogenesis and processing machinery have been implicated in several malignancies. Such mutations can lead to global miRNA misregulation, which may promote many of the well-known hallmarks of cancer. Interestingly, recent evidence also suggests that oncogenic Kristen rat sarcoma viral oncogene homolog (KRAS) mutations act in part by modulating the activity of members of the miRNA regulatory pathway. Here, we highlight the vital role mutations in the miRNA core machinery play in promoting malignant transformation. Furthermore, we discuss how mutant KRAS can simultaneously impact multiple steps of miRNA processing and function to promote tumorigenesis. Although the ability of KRAS to hijack the miRNA regulatory pathway adds a layer of complexity to its oncogenic nature, it also provides a potential therapeutic avenue that has yet to be exploited in the clinic. Moreover, concurrent targeting of mutant KRAS and members of the miRNA core machinery represents a potential strategy for treating cancer.

Phosphomimetic Dicer S1016E triggers a switch to glutamine metabolism in gemcitabine-resistant pancreatic cancer

Objective

Dicer is an enzyme that processes microRNAs (miRNAs) precursors into mature miRNAs, which have been implicated in various aspects of cancer progressions, such as clinical aggressiveness, prognosis, and survival outcomes. We previously showed that high expression of Dicer is associated with gemcitabine (GEM) resistance in pancreatic ductal adenocarcinoma (PDAC); thus, in this study, we aimed to focus on how Dicer is involved in GEM resistance in PDAC, including cancer prognosis, cell proliferation, and metabolic regulation.

Methods

We generated stable shRNA knockdown of Dicer in GEM-resistant PANC-1 (PANC-1 GR) cells and explored cell viability by MTT and clonogenicity assays. Metabolomic profiling was employed to investigate metabolic changes between parental cells, PANC-1, and PANC-1 GR cells, and further implied to compare their sensitivity to the glutaminase inhibitor, CB839, and GEM treatments. To identify putative phosphorylation site involves with Dicer and its effects on GEM resistance in PDAC cells, we further generated phosphomimetic or phosphomutant Dicer at S1016 site and examined the changes in drug sensitivity, metabolic alteration, and miRNA regulation.

Results

We observed that high Dicer levels in pancreatic ductal adenocarcinoma cells were positively correlated with advanced pancreatic cancer and acquired resistance to GEM. Metabolomic analysis indicated that PANC-1 GR cells rapidly utilised glutamine as their major fuel and increased levels of glutaminase (GLS): glutamine synthetase (GLUL) ratio which is related to high Dicer expression. In addition, we found that phosphomimetic Dicer S1016E but not phosphomutant Dicer S1016A facilitated miRNA maturation, causing an imbalance in GLS and GLUL and resulting in an increased response to GLS inhibitors.

Conclusion

Our results suggest that phosphorylation of Dicer on site S1016 affects miRNA biogenesis and glutamine metabolism in GEM-resistant pancreatic cancer.

•

Dicer expression is positively correlated with advanced pancreatic cancer.

•

Dicer expression is significantly correlated with high level of GLS and GLS/GLUL ratio.

•

Phosphomimetic Dicer S1016E enhances glutamine consumption and GLS inhibitor sensitivity.

•

Phosphomimetic Dicer S1016E facilitates miRNAs maturation to increase GLS/GLUL ratio.

Dicer-mediated miR-200b expression contributes to cell migratory/invasive abilities and cancer stem cells properties of breast cancer cells

Distant metastasis is the leading cause of death in patients with breast cancer. Despite considerable treatment advances, the clinical outcomes of patients with metastatic breast cancer remain poor. CSCs can self-renew, enhancing cancer progression and metastasis. Dicer, a microRNA (miRNA) processing–related enzyme, is required for miRNA maturation. Imbalanced Dicer expression may be pivotal in cancer progression. However, whether and how Dicer affects the stemness of metastatic breast cancer cells remains unclear. Here, we hypothesized that Dicer regulates the migration, invasion, and stemness of breast cancer cells. We established highly invasive cell lines (MCF-7/I-3 and MDA-MB-231/I-3) and observed that Dicer expression was conspicuously lower in the highly invasive cells than in the parental cells. The silencing of Dicer significantly enhanced the cell migratory/invasive abilities and CSCs properties of the breast cancer cells. Conversely, the overexpression of Dicer in the highly invasive cells reduced their migration, invasion, and CSCs properties. Our bioinformatics analyses demonstrated that low Dicer levels were correlated with increased breast cancer risk. Suppression of Dicer inhibited miR-200b expression, whereas miR-200b suppression recovered Dicer knockdown–induced migration, invasion, and cancer stem cells (CSCs) properties of the breast cancer cells. Thus, our findings reveal that Dicer is a crucial regulator of the migration, invasion, and CSCs properties of breast cancer cells and is significantly associated with poor survival in patients with breast cancer.

Genome-Wide CRISPR Screening Identifies DCK and CCNL1 as Genes That Contribute to Gemcitabine Resistance in Pancreatic Cancer

Simple Summary

Pancreatic cancer is one of the most lethal cancers. Although complete surgical resection is the only curative treatment for pancreatic cancer, a late diagnosis is common and makes surgical treatment infeasible. Therefore, most patients receive chemotherapy to reduce the tumor burden. Gemcitabine has been the main chemotherapy for pancreatic cancer for over a decade; however, chemoresistance has emerged as a significant challenge to the efficacy of chemotherapy. In this study, we applied genome-wide CRISPR/Cas9 loss-of-function screening with gemcitabine treatment to identify DCK and CCNL1 as genes that contribute to gemcitabine resistance in pancreatic cancer and explored the mechanism of CCNL1-related gemcitabine resistance.

Abstract

Pancreatic cancer is one of the most lethal cancers. Due to the difficulty of early diagnosis, most patients are diagnosed with metastasis or advanced-stage cancer, limiting the possibility of surgical treatment. Therefore, chemotherapy is applied to improve patient outcomes, and gemcitabine has been the primary chemotherapy drug for pancreatic cancer for over a decade. However, drug resistance poses a significant challenge to the efficacy of chemotherapy. The CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) gene-editing system is a powerful tool, and researchers have developed CRISPR/Cas9 library screening as a means to identify the genes associated with specific phenotype changes. We performed genome-wide CRISPR/Cas9 knockout screening in the mouse pancreatic cancer cell line TB32047 with gemcitabine treatment and identified deoxycytidine kinase (DCK) and cyclin L1 (CCNL1) as the top hits. We knocked out DCK and CCNL1 in the TB32047 and PANC1 cell lines and confirmed that the loss of DCK or CCNL1 enhanced gemcitabine resistance in pancreatic cells. Many researchers have addressed the mechanism of DCK-related gemcitabine resistance; however, no study has focused on CCNL1 and gemcitabine resistance. Therefore, we explored the mechanism of CCNL1-related gemcitabine resistance and found that the loss of CCNL1 activates the ERK/AKT/STAT3 survival pathway, causing cell resistance to gemcitabine treatment.

Current and Future Therapies for Pancreatic Ductal Adenocarcinoma

Simple Summary

Pancreatic cancer is the fourth leading cause of cancer-related mortality worldwide. The poor survival associated with this disease is due to delayed diagnosis, a lack of reliable biomarkers, and tumour resistance to treatment. Currently, surgery is the only curative treatment option, but few patients are eligible for this procedure. Developing resistance to current chemotherapies such as gemcitabine has led to a reduction in effective therapy options for patients and an urgent requirement for the development of novel therapeutic avenues. Potential success has been noted in therapeutic approaches such as synthetic lethality and immunotherapy. An array of clinical trials are currently recruiting, primarily in the area of monoclonal antibodies in combination with other therapies such as chemotherapy and immune checkpoint inhibitors. This review article aims to highlight the potential these therapies have to improve patient prognosis and survival.

Abstract

Pancreatic cancer is one of the leading causes of cancer-related death worldwide. This is due to delayed diagnosis and resistance to traditional chemotherapy. Delayed diagnosis is often due to the broad range of non-specific symptoms that are associated with the disease. Resistance to current chemotherapies, such as gemcitabine, develops due to genetic mutations that are either intrinsic or acquired. This has resulted in poor patient prognosis and, therefore, justifies the requirement for new targeted therapies. A synthetic lethality approach, that targets specific loss-of-function mutations in cancer cells, has shown great potential in pancreatic ductal adenocarcinoma (PDAC). Immunotherapies have also yielded promising results in the development of new treatment options, with several currently undergoing clinical trials. The utilisation of monoclonal antibodies, immune checkpoint inhibitors, adoptive cell transfer, and vaccines have shown success in several neoplasms such as breast cancer and B-cell malignancies and, therefore, could hold the same potential in PDAC treatment. These therapeutic strategies could have the potential to be at the forefront of pancreatic cancer therapy in the future. This review focuses on currently approved therapies for PDAC, the challenges associated with them, and future directions of therapy including synthetically lethal approaches, immunotherapy, and current clinical trials.

Pressure Loading Induces DNA Damage in Human Hepatocyte Line L02 Cells via the ERK1/2-Dicer Signaling Pathway

Alteration of liver tissue mechanical microenvironment is proven to be a key factor for causing hepatocyte injury and even triggering the occurrence of hepatocellular carcinoma; however, the underlying mechanisms involved are not fully understood. In this study, using a customized, pressure-loading device, we assess the effect of pressure loading on DNA damage in human hepatocytes. We show that pressure loading leads to DNA damage and S-phase arresting in the cell cycle, and activates the DNA damage response in hepatocytes. Meanwhile, pressure loading upregulates Dicer expression, and its silencing exacerbates pressure-induced DNA damage. Moreover, pressure loading also activates ERK1/2 signaling molecules. Blockage of ERK1/2 signaling inhibits pressure-upregulated Dicer expression and exacerbates DNA damage by suppressing DNA damage response in hepatocytes. Our findings demonstrate that compressive stress loading induces hepatocyte DNA damage through the ERK1/2–Dicer signaling pathway, which provides evidence for a better understanding of the link between the altered mechanical environment and liver diseases.

Calcium channel blockers potentiate gemcitabine chemotherapy in pancreatic cancer

There is currently no effective treatment for pancreatic ductal adenocarcinoma (PDAC). While palliative chemotherapy offers a survival benefit to most patients, nearly all will eventually progress on treatment and long-term survivability remains poor. Given the lack of subsequent line treatment options, in this study, we sought to identify novel strategies to prevent, delay, or overcome resistance to gemcitabine, one of the most widely used medications in PDAC. Using a combination of single-cell RNA sequencing and high-throughput proteomic analysis, we identified a subset of gemcitabine-resistant tumor cells enriched for calcium/calmodulin signaling. Pharmacologic inhibition of calcium-dependent calmodulin activation led to the rapid loss of drug-resistant phenotypes in vitro, which additional single-cell RNA sequencing identified was due to impaired activation of the RAS/ERK signaling pathway. Consistent with these observations, calcium chelation or depletion of calcium in the culture media also impaired ERK activation in gemcitabine-resistant cells, and restored therapeutic responses to gemcitabine in vitro. We observed similar results using calcium channel blockers (CCBs) such as amlodipine, which inhibited prosurvival ERK signaling in vitro and markedly enhanced therapeutic responses to gemcitabine in both orthotopic xenografts and transgenic models of PDAC. Combined, these results offer insight into a potential means of gemcitabine resistance and suggest that select CCBs may provide a clinical benefit to PDAC patients receiving gemcitabine-based chemotherapy.

Noncoding RNAs and their therapeutics in paclitaxel chemotherapy: Mechanisms of initiation, progression, and drug sensitivity

The identification of agents that can reverse drug resistance in cancer chemotherapy, and enhance the overall efficacy is of great interest. Paclitaxel (PTX) belongs to taxane family that exerts an antitumor effect by stabilizing microtubules and inhibiting cell cycle progression. However, PTX resistance often develops in tumors due to the overexpression of drug transporters and tumor-promoting pathways. Noncoding RNAs (ncRNAs) are modulators of many processes in cancer cells, such as apoptosis, migration, differentiation, and angiogenesis. In the present study, we summarize the effects of ncRNAs on PTX chemotherapy. MicroRNAs (miRNAs) can have opposite effects on PTX resistance (stimulation or inhibition) via influencing YES1, SK2, MRP1, and STAT3. Moreover, miRNAs modulate the growth and migration rates of tumor cells in regulating PTX efficacy. PIWI-interacting RNAs, small interfering RNAs, and short-hairpin RNAs are other members of ncRNAs regulating PTX sensitivity of cancer cells. Long noncoding RNAs (LncRNAs) are similar to miRNAs and can modulate PTX resistance/sensitivity by their influence on miRNAs and drug efflux transport. The cytotoxicity of PTX against tumor cells can also be affected by circular RNAs (circRNAs) and limitation is that oncogenic circRNAs have been emphasized and experiments should also focus on onco-suppressor circRNAs.

DICER activates autophagy and promotes cisplatin resistance in non-small cell lung cancer by binding with let-7i-5p

OBJECTIVE

Drug resistance is the main obstacle in the treatment of non-small cell lung cancer (NSCLC). This study aimed to explore the mechanism of DICER in NSCLC resistance and its downstream signaling pathways.

METHODS

The A549 cisplatin (DDP)-resistant strain A549/DDP was established. A549/DDP cells were transfected with DICER- and let-7i-5p-related vectors, and treated with autophagy activator rapamycin. The cell viability and apoptosis were tested by CCK-8 assay and flow cytometry, respectively. The formation of autophagosomes was observed with a transmission electron microscopy. RT-qPCR and Western blot assay were conducted to detect expression levels of DICER, let-7i-5p, autophagy-related proteins, and the PI3K/AKT/mTOR pathway-related proteins. The dual luciferase reporter gene assay was implemented to confirm the targeted binding of DICER and let-7i-5p.

RESULTS

DICER was highly expressed in DDP-resistant NSCLC tissues and cells, and DICER could target and negatively regulate the expression of let-7i-5p. DDP treatment could inhibit the viability and promote cell apoptosis of A549/DDP cells. Downregulation of DICER in A549/DDP cells exhibited a decrease of cell viability, a decreased ratio of LC3-II/LC3-I and autophagosomes, together with an elevation of cell apoptosis rate and the phosphorylation levels of PI3K/AKT/mTOR. Treatment of rapamycin and let-7i-5p inhibitor reversed the effects of downregulated DICER in cell viability, ratio of LC3-II/LC3-I, autophagosomes, cell apoptosis rate and the phosphorylation levels of PI3K/AKT/mTOR in A549/DDP cells.

CONCLUSION

Our research suggests that DICER promotes autophagy and DDP resistance in NSCLC through downregulating let-7i-5p, and inhibits the activation of PI3K/AKT/mTOR pathway.

MicroRNAs: The Link between the Metabolic Syndrome and Oncogenesis

Metabolic syndrome (MetS) represents a cluster of disorders that increase the risk of a plethora of conditions, in particular type two diabetes, cardiovascular diseases, and certain types of cancers. MetS is a complex entity characterized by a chronic inflammatory state that implies dysregulations of adipokins and proinflammatory cytokins together with hormonal and growth factors imbalances. Of great interest is the implication of microRNA (miRNA, miR), non-coding RNA, in cancer genesis, progression, and metastasis. The adipose tissue serves as an important source of miRs, which represent a novel class of adipokines, that play a crucial role in carcinogenesis. Altered miRs secretion in the adipose tissue, in the context of MetS, might explain their implication in the oncogenesis. The interplay between miRs expressed in adipose tissue, their dysregulation and cancer pathogenesis are still intriguing, taking into consideration the fact that miRNAs show both carcinogenic and tumor suppressor effects. The aim of our review was to discuss the latest publications concerning the implication of miRs dysregulation in MetS and their significance in tumoral signaling pathways. Furthermore, we emphasized the role of miRNAs as potential target therapies and their implication in cancer progression and metastasis.