Autophagy regulated by miRNAs in colorectal cancer progression and resistance

Epigenetic modulation of autophagy pathway by small molecules in colorectal cancer: a systematic review

PURPOSE

Colorectal cancer (CRC) remains a global health challenge with limited treatment success due to drug resistance. Recent research highlights the potential of small molecules to modulate CRC by targeting epigenetics or autophagy pathways. This systematic review explores the epigenetic effect of small molecules on autophagy in CRC, aiming to identify novel therapeutic strategies.

METHODS

Following PRISMA guidelines, we systematically reviewed 508 studies from PubMed, Scopus, and Web of Science databases until August 13, 2023.

RESULTS

Eight studies met inclusion criteria, examining the role of small molecules as epigenetic modulators (Histone acetylation/deacetylation, DNA methylation/demethylation and gene expression regulation by miRNAs) influencing the autophagy pathway in CRC. The studies encompassed in vitro and animal model in vivo studies. Small molecules exhibited diverse effects on autophagy in CRC. For instance, panobinostat promoted autophagy leading to CRC cell death, while aspirin inhibited autophagy flux, reducing aspirin-mediated CRC cell death. The epigenetic modulation of autophagy by various small molecules differently affects their anticancer effect, which underscores the complexity of therapeutic interventions.

CONCLUSION

Understanding the intricate dynamics among small molecules, epigenetic modifications, and autophagy in CRC is crucial for developing targeted therapeutic strategies. Considering the dual role of autophagy in tumorigenesis and tumor suppression, administration of these small molecules may differently affect the cancer cell fate and drug response or resistance based on their effect on the autophagy pathway. Therefore, recognition of the epigenetics mechanism of anticancer small molecules on autophagy may contribute to deciding how to prescribe them for better CRC treatment.

Autophagy: Dual roles and perspective for clinical treatment of colorectal cancer

Colorectal cancer (CRC) raises concerns to people because of its high recurrence and metastasis rate, diagnosis challenges, and poor prognosis. Various studies have shown the association of altered autophagy with tumorigenesis, tumor-stroma interactions, and resistance to cancer therapy in CRC. Autophagy is a highly conserved cytosolic catabolic process in eukaryotes that plays distinct roles in CRC occurrence and progression. In early tumorigenesis, autophagy may inhibit tumor growth through diverse mechanisms, whereas it exhibits a tumor promoting function in CRC progression. This different functions of autophagy in CRC occurrence and progression make developing therapies targeting autophagy complicated. In this review, we discuss the classification and process of autophagy as well as its dual roles in CRC, functions in the tumor microenvironment, cross-talk with apoptosis, and potential usefulness as a CRC therapeutic target.

Blockage of Nrf2 and autophagy by L-selenocystine induces selective death in Nrf2-addicted colorectal cancer cells through p62-Keap-1-Nrf2 axis

Persistent Nrf2 activation is typically noted in many cancers, including colorectal cancer (CRC), aiding cancer cells in overcoming growth stress and promoting cancer progression. Sustained Nrf2 activation, which is beneficial for cancer cells, is called "Nrf2 addiction"; it is closely associated with malignancy and poor prognosis in patients with cancer. However, Nrf2 inhibitors may have adverse effects on normal cells. Here, we found that the selenocompound L-selenocystine (SeC) is selectively cytotoxic in the Nrf2-addicted CRC cell line WiDr cells, but not in non-Nrf2-addicted mesenchymal stem cells (MSCs) and normal human colon cells. Another CRC cell line, C₂BBe₁, which harbored lower levels of Nrf2 and its downstream proteins were less sensitive to SeC, compared with the WiDr cells. We further demonstrated that SeC inhibited Nrf2 and autophagy activation in the CRC cells. Antioxidant GSH pretreatment partially rescued the CRC cells from SeC-induced cytotoxicity and Nrf2 and autophagy pathway inhibition. By contrast, SeC activated Nrf2 and autophagy pathway in non-Nrf2-addicted MSCs. Transfecting WiDr cells with Nrf2-targeting siRNA decreased persistent Nrf2 activation and alleviated SeC cytotoxicity. In KEAP1-knockdown C₂BBe₁ cells, Nrf2 pathway activation increased SeC sensitivity and cytotoxicity. In conclusion, SeC selectively attacks cancer cells with constitutively activated Nrf2 by reducing Nrf2 and autophagy pathway protein expression through the P62-Nrf2-antioxidant response element axis and eventually trigger cell death.

Employing bioinformatics analysis to identify hub genes and microRNAs involved in colorectal cancer

The third leading cause of cancer-related deaths in the world, colorectal cancer (CRC) is a global health issue that should be addressed in both diagnostics and therapeutics to improve patient survival rate. Today, microarray data analysis is increasingly being used as a novel and effective method for classification of malignancies and making prognostic assessments. Built upon the concept of microarray data analysis and aimed at the identification of CRC-associated genes, our study has adopted an integrative analysis for the gene expression patterns of four microarray datasets in gene expression omnibus (GEO) and microRNAs (miRNAs) expression profiles. We downloaded four gene expression profiles, i.e., GSE37182, GSE25070, GSE10950, and GSE113513, miRNAs gene expression profiles and differentially expressed genes (DEGs). We used R software, the DAVID database, protein-protein interaction (PPI) networks, the Cytoscape program and receiver operating characteristic (ROC) curve for data analysis. Out of the four gene expression profiles, a total of 43 common DEGs were identified, including 10 hub genes, SLC26A3, CLCA1, GUCA2A, MS4A12, CLCA4, GUCA2B, KRT20, AQP8, MAOA, and ADH1A, and four differentially expressed miRNAs, miR-552, miR-423-5p, miR-502-3p, and miR-490-5p. The highly enriched modes of the signaling pathways among these DEGs were speculated to be involved in various processes including nitrogen metabolism, mineral absorption, pancreatic secretions, and tyrosine metabolism in Kyoto encyclopedia of genes and genomes (KEGG) database. According to our bioinformatics analysis, the DEGs identified in the present study could be considered as significant hallmarks in the molecular mechanisms of CRC development. Our findings may assist scientists with developing novel strategies not only for prediction of CRC, but also for screening and early diagnosis, and treatment of CRC patients.

Autophagy Paradox of Cancer: Role, Regulation, and Duality

Autophagy, a catabolic process, degrades damaged and defective cellular materials through lysosomes, thus working as a recycling mechanism of the cell. It is an evolutionarily conserved and highly regulated process that plays an important role in maintaining cellular homeostasis. Autophagy is constitutively active at the basal level; however, it gets enhanced to meet cellular needs in various stress conditions. The process involves various autophagy-related genes that ultimately lead to the degradation of targeted cytosolic substrates. Many factors modulate both upstream and downstream autophagy pathways like nutritional status, energy level, growth factors, hypoxic conditions, and localization of p53. Any problem in executing autophagy can lead to various pathological conditions including neurodegeneration, aging, and cancer. In cancer, autophagy plays a contradictory role; it inhibits the formation of tumors, whereas, during advanced stages, autophagy promotes tumor progression. Besides, autophagy protects the tumor from various therapies by providing recycled nutrition and energy to the tumor cells. Autophagy is stimulated by tumor suppressor proteins, whereas it gets inhibited by oncogenes. Due to its dynamic and dual role in the pathogenesis of cancer, autophagy provides promising opportunities in developing novel and effective cancer therapies along with managing chemoresistant cancers. In this article, we summarize different strategies that can modulate autophagy in cancer to overcome the major obstacle, i.e., resistance developed in cancer to anticancer therapies.

The interaction mechanism between autophagy and apoptosis in colon cancer

Autophagy and apoptosis play crucial roles in tumorigenesis. Recent studies have shown that autophagy and apoptosis have a cross-talk relationship in anti-tumor therapy. It is well established that apoptosis is one of the main pathways of tumor cell death. While autophagy can occurs in tumors with opposite function: protective autophagy and lethal autophagy. Protective autophagy can inhibit tumor apoptosis induced by anticancer drugs, while lethal autophagy can induce tumor cell apoptosis in cooperation with anticancer drugs. Hence, autophagy and apoptosis have synergistic and antagonistic effects in tumor. Colorectal cancer is a common malignant tumor with high morbidity and mortality. In recent years, colorectal carcinoma has achieved improved clinical efficacy with drug treatment. Nonetheless, increasing drug-resistance limit the treatment efficacy, highlighting the urgency of exploring the molecular events that drive drug resistance. Researchers have found that autophagy is one of the major factors leading to drug resistance in colon cancer. Therefore, elucidating the interaction between autophagy and apoptosis is helpful to improve the efficacy of anticancer drugs in clinical treatment of colorectal cancer. This review attaches great importance to the relationship between autophagy and apoptosis and related factors in colorectal cancer.

Exosome-transmitted miR-567 reverses trastuzumab resistance by inhibiting ATG5 in breast cancer

Trastuzumab is commonly used in the treatment of human epidermal growth factor receptor-2 positive (HER-2+) breast cancer, but its efficacy is often limited by the emergence of chemoresistance. Recent studies indicate that exosomes act as vehicles for exchange of genetic cargo between heterogeneous populations of tumor cells, engendering a transmitted drug resistance for cancer development and progression. However, the specific contribution of breast cancer-derived exosomes is poorly understood. In this study, publicly available expression profiling data from breast cancer and bioinformatics analyses were used to screen potential miRNAs in trastuzumab resistance. A series of gain- or loss-functional assays were performed to define the function of miR-567 and ATG5 in trastuzumab resistance and autophagy, both in vitro and in vivo. Our results showed that miR-567 was significantly decreased in trastuzumab-resistant patients compared with responding patients. Moreover, miR-567 was also downregulated in trastuzumab-resistant cells compared with parental cells. Overexpression of miR-567 reversed chemoresistance, whereas silence of miR-567 induced trastuzumab resistance, both in vitro and in vivo. In addition, enhanced miR-567 could be packaged into exosomes, incorporated into receipt cells, suppressing autophagy and reversed chemoresistance by targeting ATG5. To conclude, exosomal miR-567 plays a key role in reversing trastuzumab resistance via regulating autophagy, indicating it may be a promising therapeutic target and prognostic indicator for breast cancer patients.

Development of microRNA-based therapy for pancreatic cancer

Despite extensive research efforts on diagnosis and treatment, pancreatic ductal adenocarcinoma (PDAC) remains a devastating disease and the third leading cause of cancer-related death in the United States. Resistance to current therapeutic approaches is a major reason for the poor survival of pancreatic patients. In order to overcome this major challenge and improve patient outcomes, we are in desperate need of novel therapeutic approaches. PDAC chemoresistance mechanisms are complex and multifaceted. Novel therapeutics must be equipped to deal with this challenge. microRNAs (miRNAs) have emerged as strong candidates to fill this role due to their multitargeted function. miRNAs have been shown to have important roles in pancreatic cancer resistance. In this review, we summarize the recent advancement in miRNA research related to PDAC therapeutic resistance mechanisms and the potential of miRNAs as therapeutic agents for future clinical management of PDAC.

The Role of Extracellular Vesicles as Modulators of the Tumor Microenvironment, Metastasis and Drug Resistance in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide, with high morbidity and mortality rates. A number of factors including modulation of the tumor microenvironment, high metastatic capability, and resistance to treatment have been associated with CRC disease progression. Recent studies have documented that tumor-derived extracellular vesicles (EVs) play a significant role in intercellular communication in CRC via transfer of cargo lipids, proteins, DNA and RNAs to the recipient tumor cells. This transfer influences a number of immune-related pathways leading to activation/differentiation/expression of immune cells and modulation of the tumor microenvironment that plays a significant role in CRC progression, metastasis, and drug resistance. Furthermore, tumor-derived EVs are secreted in large amounts in biological fluids of CRC patients and as such the expression analysis of EV cargoes have been associated with prognosis or response to therapy and may be a source of therapeutic targets. This review aims to provide a comprehensive insight into the role of EVs in the modulation of the tumor microenvironment and its effects on CRC progression, metastasis, and drug resistance. On the other hand, the potential role of CRC derived EVs as a source of biomarkers of response and therapeutic targets will be discussed in detail to understand the dynamic role of EVs in CRC diagnosis, treatment, and management.

Autophagy in exposure to environmental chemicals

Autophagy is a catabolic pathway, which breaks down old and damaged cytoplasmic material into basic biomolecules through lysosome-mediated digestion thereby recycling cellular material. In this way, autophagy prevents the accumulation of damaged cellular components inside cells and reduces metabolic stress and toxicity. The basal level of autophagy is generally low but essential for maintaining the turnover of proteins and other molecules. The level is, however, increased in response to various stress conditions including chemical stress. This elevation in autophagy is intended to restore energy balance and improve cell survival in stress conditions. However, aberrant and/or deficient autophagy may also be involved in the aggravation of chemical-caused insults. Thus, the overall role of autophagy in chemical-induced toxicity is complex and only a limited number of environmental chemicals have been studied from this point of view. Autophagy is associated with many of the chemical-caused cytotoxic mechanisms, including mitochondrial dysfunction, DNA damage, oxidative stress, changes in the endoplasmic reticulum, impairment of lysosomal functions, and inflammation. This mini-review describes autophagy and its involvement in the responses to some common environmental exposures including airborne particulate matter, nanoparticles and tobacco smoke as well as to some common single environmental chemicals.

Decreased Expression of MicroRNA-107 in B Lymphocytes of Patients with Antibody-Mediated Renal Allograft Rejection

MicroRNAs (miRNAs) are small noncoding RNA molecules that participate in normal B cell lineage development through posttranscriptional gene regulation. Antibody-mediated renal allograft rejection (ABMR) is emerging as one of the most common serious threats to renal transplant patients. In this study, we explored the role of miRNAs in the pathogenesis of ABMR. The differentially expressed miRNAs were identified by Affymetrix miRNA microarray analysis using B lymphocytes from 5 recipients and 5 volunteers. Based on quantitative RT-PCR, the expression levels of miR-107 were lower in the B lymphocytes from recipients than in those from volunteers. Computational analysis predicted that 3'-untranslated region of the autophagy-related protein 12 (ATG12) mRNA was targeted by miR-107, and we identified ATG12 as a target of miR-107 by Luciferase assay. Importantly, the expression levels of ATG12 in B lymphocytes of recipients were higher than those in the volunteer group, and miR-107 mimic significantly decreased ATG12 expression and formation of autolysosomes in B lymphocytes of recipients. Furthermore, we observed that levels of autophagy in B lymphocytes of transplant recipients were higher than those in B cells from volunteers. These findings suggest that miR-107 may contribute to the regulation of autophagy via targeting ATG12. Lastly, treatment with an miR-107 mimic caused the decrease in the secretion of IgG and IgM antibodies from B lymphocytes of transplant recipients, indicating that deregulated miR-107 could be involved in the pathogenesis of ABMR. Taken together, we propose that decreased miR-107 expression is associated with autophagy activation in B lymphocytes from patients with ABMR.

Role of DDX53 in taxol-resistance of cervix cancer cells in vitro

Cancer/Testis antigen DDX53 shows high expression level in various tumors and is involved in anti-cancer drug resistance. However, the functional study of DDX53 in cervix cancer remains unknown. In this study, the role of DDX53 in taxol-resistance of cervix cancer cells was investigated. In taxol-resistant Hela^TR cells, DDX53 was significantly increased as compared to the parental HeLa cells. Hela^TR cells also showed upregulation of multidrug resistant gene MDR1, invasive characteristics and decreased apoptosis. In addition, increased autophagy level was observed in Hela^TR cells. Overexpression of DDX53 in HeLa and SiHa markedly led to greater resistance to taxol and cisplatin, whereas knockdown of DDX53 in Hela^TR cells restored sensitivity, demonstrating that DDX53 regulated taxol resistance in cervix cancer cells. DDX53 overexpression in HeLa and SiHa cells enhanced invasion, migration and anchorage independent growth, DDX53 knockdown showed inverse effects in HeLa^TR cells. When DDX53 expression was suppressed by siRNA, autophagic flux and drug resistance of Hela^TR cells were decreased. In addition, DDX53 was upregulated in cervix cancer tissues from patient with a glassy cell carcinoma of cervix. Taken together, these results suggest that DDX53 plays a critical role in taxol-resistance by activating autophagy and a potential therapeutic target for the treatment of taxol-resistant cervix cancer.

Autophagy in health and disease: A comprehensive review

Autophagy, a conserved catabolic process, plays an immensely significant role in a variety of diseases. However, whether it imparts a protective function in diseases remains debatable. During aging, autophagy gradually subsides, manifested by the reduced formation of autophagic vacuoles and improper fusion of these vacuoles with the lysosomes. Similarly, in neurodegenerative disorders, accumulation of tau and synuclein proteins has been attributed to the decline in the autophagic removal of proteins. Equivalently, lysosomal disorders show an impairment of the autophagic process leading to the accumulation of lipid molecules within lysosomes. On the other hand, activation of the autophagic pathway has also proved beneficial in evading various foreign pathogens, thereby contributing to the innate immunity. In the context of cancer, autophagy has shown to play a puzzling role where it serves as a tumor suppressor during initial stages but later protects the tumor cells from the immune system defense mechanisms. Similarly, muscular and heart disorders have been shown to be positively and negatively regulated by autophagy, respectively. In the present review, we, therefore, present a comprehensive review on the role of autophagy in various diseases and their corresponding outcomes.

Barbaloin loaded polydopamine-polylactide-TPGS (PLA-TPGS) nanoparticles against gastric cancer as a targeted drug delivery system: Studies in vitro and in vivo

Gastric cancer is the third leading cause of cancer-associated death worldwide. Although a decrease in its incidence is observed, gastric cancer still poses a major clinical challenge due to poor prognosis and limited treatments. Barbaloin (BBL) is a main medicinal composition of the Chinese traditional medicine aloe vera. BBL has various bioactivities, including anti-oxidant, anti-inflammatory and anti-tumor properties. Polydopamine (pD)-based surface modification is easy to functionalize polymeric nanoparticles (NPs) surfaces with ligands and/or additional polymeric layers. In the present study, BBL-loaded formulations was developed with pD-modified NPs, which was synthesized by polylactide-TPGS (PLA-TPGS) (pD-PLA-TPGS/NPs). And galactosamine (Gal) was conjugated on the prepared NPs (Gal-pD-PLA-TPGS/NPs) for targeting the gastric cancer cells. Here, we found that BBL-loaded Gal-pD-PLA-TPGS/NPs showed the highest cellular uptake efficacy in gastric cancer cells. Gal-pD-PLA-TPGS/NPs more significantly reduced the gastric cancer cell viability. Further, greater apoptosis, autophagy and ROS generation was induced by Gal-pD-PLA-TPGS/NPs in gastric cancer cells. Additionally, compared to the other two NPs, Gal-pD-PLA-TPGS/NPs most markedly decreased ATP levels in gastric cancer cells. In vivo, Gal-pD-PLA-TPGS/NPs were specifically targeted to tumor site. Moreover, Gal-pD-PLA-TPGS/NPs exhibited the most anti-tumor effects, as evidenced by the lowest tumor volume and tumor weight. Of note, there was no significant difference was observed in body and liver weight, as well as the histological changes in major organs isolated from each group of mice. Together, the findings indicated that BBL-loaded Gal-pD-PLA-TPGS/NPs could be targeted to gastric cancer cells to suppress tumor progression without toxicity.

MiR-22-3p Regulates Cell Proliferation and Inhibits Cell Apoptosis through Targeting the eIF4EBP3 Gene in Human Cervical Squamous Carcinoma Cells

Background: MicroRNAs (miRNAs) are non-coding small RNAs that function as negative regulators of gene expression and are involved in tumour biology. The eIF4E-binding proteins (eIF4EBPs) play essential roles in preventing translation initiation and inhibiting protein synthesis at a global or message-specific level in a variety of tumours. Methods: According to comparative miRNA profiles of clinical cervical cancer and non-cancerous cervical tissue specimens, several miRNAs were aberrantly expressed in the cervical cancer samples. C33a and SiHa cell proliferation and apoptosis were detected using methyl thiazolyl tetrazolium (MTT) and flow cytometry assays, respectively. Results: Among the aberrantly expressed miRNAs, miR-22-3p was significantly differentially expressed in cervical cancer tissues and was highly associated with cervical cancer cell growth regulation. In addition, bioinformatic predictions and experimental validation were used to identify whether eIF4E-binding protein 3 (eIF4EBP3) was a direct target of miR-22-3p; eIF4EBP3 protein levels were generally low in the cervical cancer tissues. Furthermore, functional studies revealed that either a miR-22-3p inhibitor or eIF4EBP3 overexpression could induce apoptosis in cervical cancer cells in vitro. Importantly, we found that eIF4EBP3 accumulation could significantly attenuate cervical cancer cell proliferation triggered by a miR-22-3p mimic as well as enhance apoptosis in cervical cancer cells. Conclusion: Taken together, our data provide primary proof that miR-22-3p can induce cervical cancer cell growth at least in part by up-regulating its expression to decrease eIF4EBP3 expression levels; miR-22-3p thus holds promise as a prognostic biomarker and potential therapeutic target for treating cervical cancer.