miR-503-5p confers drug resistance by targeting PUMA in colorectal carcinoma

Exosomal non-coding RNAs: Blueprint in colorectal cancer metastasis and therapeutic targets

Colorectal cancer (CRC) is ranked as the world's third-most prevalent cancer, and metastatic CRC considerably increases cancer-related fatalities globally. A number of complex mechanisms that are strictly controlled at the molecular level are involved in metastasis, which is the primary reason for death in people with CRC. Recently, it has become clear that exosomes, which are small extracellular vesicles released by non-tumorous and tumorigenic cells, play a critical role as communication mediators among tumor microenvironment (TME). To facilitate communication between the TME and cancer cells, non-coding RNAs (ncRNAs) play a crucial role and are recognized as potent regulators of gene expression and cellular processes, such as metastasis and drug resistance. NcRNAs are now recognized as potent regulators of gene expression and many hallmarks of cancer, including metastasis. Exosomal ncRNAs, like miRNAs, circRNAs, and lncRNAs, have been demonstrated to influence a number of cellular mechanisms that contribute to CRC metastasis. However, the molecular mechanisms that link exosomal ncRNAs with CRC metastasis are not well understood. This review highlights the essential roles that exosomal ncRNAs play in the progression of CRC metastatic disease and explores the therapeutic choices that are open to patients who have CRC metastases. However, exosomal ncRNA treatment strategy development is still in its early phases; consequently, additional investigation is required to improve delivery methods and find novel therapeutic targets as well as confirm the effectiveness and safety of these therapies in preclinical and clinical contexts.

P53‑microRNA interactions regulate the response of colorectal tumor cells to oxaliplatin under normoxic and hypoxic conditions

Oxaliplatin (OXA)‑containing regimens are used as first‑line chemotherapy in colorectal cancer (CRC). However, OXA resistance remains a major challenge in CRC treatment. CRC cells that adapt to hypoxia can potentially develop OXA resistance, and the underlying molecular mechanisms still need to be further investigated. In the current study, the OXA drug sensitivity of two CRC cell lines, HCT116 (TP53WT) and HT29 (TP53MT), was compared under both normoxic and hypoxic conditions. It was found that under normoxic condition, HCT116 cells showed significantly higher OXA sensitivity than HT29 cells. However, both cell lines showed remarkable OXA resistance under hypoxic conditions. It was also revealed that P53 levels were increased after OXA and hypoxia treatment in HCT116 cells but not in HT29 cells. Notably, knocking down P53WT decreased normoxic but increased hypoxic OXA sensitivity in HCT116 cells, which did not exist in HT29 cells. Molecular analysis indicated that P53WT activated microRNA (miR)‑26a and miR‑34a in OXA treatment and activated miR‑23a in hypoxia treatment. Cell proliferation experiments indicated that a high level of miR‑23a decreased OXA sensitivity and that a high level of miR‑26a or miR‑34a increased OXA sensitivity in HCT116 cells. Additionally, it was demonstrated that miR‑26a, miR‑34a and miR‑23a affect cell apoptosis through regulation of MCL‑1, EZH2, BCL‑2, SMAD 4 and STAT3. Taken together, the present findings revealed the dual function of P53 in regulating cellular chemo‑sensitivity and highlighted the role of P53‑miR interactions in the response of CRC cells to OXA chemotherapy under normoxic and hypoxic conditions.

Exosome-delivered circRNA circSYT15 contributes to cisplatin resistance in cervical cancer cells through the miR-503-5p/RSF1 axis

The development of chemotherapy resistance is a major obstacle for cervical cancer (CC) patients. Exosome-mediated transfer of circular RNAs (circRNAs) was found to have relevance to the CC. This study is designed to explore the role and mechanism of exosomal circRNA synaptotagmin 15 (circSYT15) on cisplatin (DDP) resistance in CC. Cell proliferation ability and apoptosis rate were detected by Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), colony formation, and flow cytometry assays. CircSYT15, microRNA-503-5p (miR-503-5p), Remodeling spacing factor 1 (RSF1) levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). Exosomes were analyzed by a transmission electron microscope and nanoparticle tracking analysis. CD63, CD81, TSC101, Bcl-2, Bax, C-caspase 3, and RSF1 protein levels were examined by western blot assay. The binding between miR-503-5p and circSYT15 or RSF1 was predicted by circBank or Starbase and then verified by a dual-luciferase reporter and RNA Immunoprecipitation (RIP). The biological role of exosomal circSYT15 in DDP resistance of CC in vivo. CircSYT15 was upregulated in the DDP-resistant CC cells and exosomes isolated from DDP-resistant CC cells. CircSYT15 knockdown repressed the proliferation and drug resistance of CC and induced apoptosis in CC cells. Exosomes shuttled circSYT15 act as a sponge to affect RSF1 expression, thereby promoting proliferation and drug resistance and repressing apoptosis of sensitive CC cells. Exosomal circSYT15 boost DDP resistance of cervical cancer in vivo. Exosome-mediated transfer of circSYT15 enhanced DDP resistance in CC partly by targeting the miR-503-5p/RSF1 axis, providing a foundation for future clinical applications of CC drug resistance.

Hsa-miR-503-5p regulates CTDSPL to accelerate cisplatin resistance and angiogenesis of lung adenocarcinoma cells

The study aimed to assess the role of hsa-miR-503-5p in cisplatin resistance and angiogenesis in LUAD and its underlying mechanisms. Hsa-miR-503-5p expression in LUAD and the target gene downstream of hsa-miR-503-5p was predicted by bioinformatics analysis. Binding relationship between the two genes was verified by dual-luciferase reporter assay. qRT-PCR was conducted for detecting gene expression in cells, CCK-8 for IC50 value, angiogenesis assay for human umbilical vein endothelial cell (HUVEC) angiogenic ability, flow cytometry for apoptosis ability, transwell assay for migration ability, and western blot for detecting the protein expression of vascular endothelial growth factor receptor 1 (VEGFR1), VEGFR2, and CTD small phosphatase like (CTDSPL). The results showed that hsa-miR-503-5p showed high expression, while its target gene CTDSPL presented decreased expression in LUAD. Hsa-miR-503-5p also had high expression in cisplatin-resistant LUAD cells. Knockdown of hsa-miR-503-5p resensitized LUAD cells to cisplatin, inhibited angiogenesis of drug-resistant cells, and reduced the protein expression of VEGFR1, VEGFR2, and EMT-related targets in cisplatin-resistant LUAD cells, but promoted the apoptosis ability. Hsa-miR-503-5p bound to CTDSPL gene and promoted cisplatin resistance and malignant progression of LUAD cells by negatively regulating CTDSPL. Our results revealed that hsa-miR-503-5p and CTDSPL may be novel targets for overcoming cisplatin resistance in LUAD.

Emerging roles of non-coding RNAs in colorectal cancer oxaliplatin resistance and liquid biopsy potential

Colorectal cancer (CRC) is one of the most common malignancies of the digestive tract, with the annual incidence and mortality increasing consistently. Oxaliplatin-based chemotherapy is a preferred therapeutic regimen for patients with advanced CRC. However, most patients will inevitably develop resistance to oxaliplatin. Many studies have reported that non-coding RNAs (ncRNAs), such as microRNAs, long non-coding RNAs, and circular RNAs, are extensively involved in cancer progression. Moreover, emerging evidence has revealed that ncRNAs mediate chemoresistance to oxaliplatin by transcriptional and post-transcriptional regulation, and by epigenetic modification. In this review, we summarize the mechanisms by which ncRNAs regulate the initiation and development of CRC chemoresistance to oxaliplatin. Furthermore, we investigate the clinical application of ncRNAs as promising biomarkers for liquid CRC biopsy. This review provides new insights into overcoming oxaliplatin resistance in CRC by targeting ncRNAs.

Genome wide analysis of circulating miRNAs in growth hormone secreting pituitary neuroendocrine tumor patients’ plasma

Background

Circulating plasma miRNAs have been increasingly studied in the field of pituitary neuroendocrine tumor (PitNET) research. Our aim was to discover circulating plasma miRNAs species associated with growth hormone (GH) secreting PitNETs versus assess how the plasma levels of discovered miRNA candidates are impacted by SSA therapy and whether there is a difference in their levels between GH secreting PitNETs versus other PitNET types and healthy individuals.

Design

We compared plasma miRNA content and levels before and after surgery focusing on GH secreting PitNET patients. Selected miRNA candidates from our data and literature were then tested in a longitudinal manner in somatostatin analogues (SSA) treatment group. Additionally, we validated selected targets in an independent GH secreting PitNET group.

Methods

miRNA candidates were discovered using the whole miRNA sequencing approach and differential expression analysis. Selected miRNAs were then analyzed using real-time polymerase chain reaction (qPCR).

Results

Whole miRNA sequencing discovered a total of 16 differentially expressed miRNAs (DEMs) in GH secreting PitNET patients’ plasma 24 hours after surgery and 19 DEMs between GH secreting PitNET patients’ plasma and non-functioning (NF) PitNET patients’ plasma. Seven miRNAs were selected for further testing of which miR-625-5p, miR-503-5p miR-181a-2-3p and miR-130b-3p showed a significant downregulation in plasma after 1 month of SSA treatment. mir-625-5p was found to be significantly downregulated in plasma of GH secreting PitNET patients vs. NF PitNET patients. miR-625-5p alongside miR-130b-3p were also found to be downregulated in GH PitNETs compared to healthy individuals.

Conclusions

Our study suggests that expression of plasma miRNAs miR-625-5p, miR-503-5p miR-181a-2-3p and miR-130b-3p in GH secreting PitNETs is affected by SSA treatment. Additionally, miR-625-5p can distinguish GH secreting PitNETs from other PitNET types and healthy controls warranting further research on these miRNAs for treatment efficacy.

Ultrasound microbubble-mediated miR-503-5p downregulation suppressed in vitro CRC progression via promoting SALL1 expression

BACKGROUND

This study compared the effect of ultrasound microbubble-mediated miR-503-5p downregulation with that of pure liposome-mediated miR-503-5p downregulation on colorectal cancer (CRC) progression and explored the downstream mechanism.

METHODS

Bioinformatics tools were utilized to predict miR-503-5p-targeted genes and CRC progression-associated genes. MiR-503-5p and sal-like 1 (SALL1) expressions in CRC cells and tissues were analyzed by qRT-PCR and/or bioinformatics tools; their correlations with overall survival and clinicopathological features of CRC patients were presented, and their interaction was validated by dual-luciferase reporter assay. CRC cells received ultrasound microbubble-mediated miR-503-5p downregulation and/or liposome-mediated miR-503-5p downregulation or SALL1 silencing. Cell phenotype changes were evaluated by flow cytometry, as well as MTT, Wound healing, Transwell and tube formation assays. E-cadherin, N-cadherin, Vimentin, B-cell lymphoma (Bcl)- 2, Cleaved caspase-3, and SALL1 expressions in cells were analyzed by Western blot.

RESULTS

Upregulated miR-503-5p in CRC tissues and cells was detected, associated with poorer cell differentiation, easier lymph node metastasis and higher TNM stages, and related to poorer prognoses of CRC patients. Ultrasound microbubble-mediated miR-503-5p downregulation relative to pure liposome-mediated miR-503-5p downregulation better decreased viability, inhibited migration, invasion and tube formation, enhanced apoptosis, upregulated SALL1, E-cadherin and Cleaved caspase-3, and downregulated miR-503-5p, N-cadherin, Vimentin and Bcl-2 in CRC cells. SALL1 was targeted by miR-503-5p, low-expressed in CRC tissues and cells and positively related to CRC patients' survival. Silencing SALL1 exerted the opposite effects, which reversed the effects of ultrasound microbubble-mediated miR-503-5p downregulation and vice versa.

CONCLUSION

Ultrasound microbubble-mediated miR-503-5p downregulation suppressed in vitro CRC progression via promoting SALL1 expression.

The Effect of Dynamic, In Vivo-like Oxaliplatin on HCT116 Spheroids in a Cancer-on-Chip Model Is Representative of the Response in Xenografts

The cancer xenograft model in which human cancer cells are implanted in a mouse is one of the most used preclinical models to test the efficacy of novel cancer drugs. However, the model is imperfect; animal models are ethically burdened, and the imperfect efficacy predictions contribute to high clinical attrition of novel drugs. If microfluidic cancer-on-chip models could recapitulate key elements of the xenograft model, then these models could substitute the xenograft model and subsequently surpass the xenograft model by reducing variation, increasing sensitivity and scale, and adding human factors. Here, we exposed HCT116 colorectal cancer spheroids to dynamic, in vivo-like, concentrations of oxaliplatin, including a 5 day drug-free period, on-chip. Growth inhibition on-chip was comparable to existing xenograft studies. Furthermore, immunohistochemistry showed a similar response in proliferation and apoptosis markers. While small volume changes in xenografts are hard to detect, in the chip-system, we could observe a temporary growth delay. Lastly, histopathology and a pharmacodynamic model showed that the cancer spheroid-on-chip was representative of the proliferating outer part of a HCT116 xenograft, thereby capturing the major driver of the drug response of the xenograft. Hence, the cancer-on-chip model recapitulated the response of HCT116 xenografts to oxaliplatin and provided additional drug efficacy information.

MicroRNAs and drug resistance in colorectal cancer with special focus on 5-fluorouracil

Colorectal cancer is globally one of the most common cancers in all age groups. The current chemotherapy combinations for colorectal cancer treatment include 5-fluorouracil-based regimens; however, drug resistance remains one of the main reasons for chemotherapy failure and disease recurrence. Many studies have determined colorectal cancer chemoresistance mechanisms such as drug efflux, cell cycle arrest, DNA damage repair, apoptosis, autophagy, vital enzymes, epigenetic, epithelial-mesenchymal transition, stem cells, and immune system suppression. Several microRNAs affect drug resistance by regulating the drug resistance-related target genes in colorectal cancer. These drug resistance-related miRNAs may be used as promising biomarkers for predicting drug response or as potential therapeutic targets for treating patients with colorectal cancer. This work reviews and discuss the role of selected microRNAs in 5-fluorouracil resistance and their molecular mechanisms in colorectal cancer.

The role of non-coding RNAs in chemotherapy for gastrointestinal cancers

Gastrointestinal (GI) cancers, including colorectal, gastric, hepatic, esophageal, and pancreatic tumors, are responsible for large numbers of deaths around the world. Chemotherapy is the most common approach used to treat advanced GI cancer. However, chemoresistance has emerged as a critical challenge that prevents successful tumor elimination, leading to metastasis and recurrence. Chemoresistance mechanisms are complex, and many factors and pathways are involved. Among these factors, non-coding RNAs (ncRNAs) are critical regulators of GI tumor development and subsequently can induce resistance to chemotherapy. This occurs because ncRNAs can target multiple signaling pathways, affect downstream genes, and modulate proliferation, apoptosis, tumor cell migration, and autophagy. ncRNAs can also induce cancer stem cell features and affect the epithelial-mesenchymal transition. Thus, ncRNAs could possibly act as new targets in chemotherapy combinations to treat GI cancer and to predict treatment response.

MicroRNA and Alternative mRNA Splicing Events in Cancer Drug Response/Resistance: Potent Therapeutic Targets

Cancer is a multifaceted disease that involves several molecular mechanisms including changes in gene expression. Two important processes altered in cancer that lead to changes in gene expression include altered microRNA (miRNA) expression and aberrant splicing events. MiRNAs are short non-coding RNAs that play a central role in regulating RNA silencing and gene expression. Alternative splicing increases the diversity of the proteome by producing several different spliced mRNAs from a single gene for translation. MiRNA expression and alternative splicing events are rigorously regulated processes. Dysregulation of miRNA and splicing events promote carcinogenesis and drug resistance in cancers including breast, cervical, prostate, colorectal, ovarian and leukemia. Alternative splicing may change the target mRNA 3'UTR binding site. This alteration can affect the produced protein and may ultimately affect the drug affinity of target proteins, eventually leading to drug resistance. Drug resistance can be caused by intrinsic and extrinsic factors. The interplay between miRNA and alternative splicing is largely due to splicing resulting in altered 3'UTR targeted binding of miRNAs. This can result in the altered targeting of these isoforms and altered drug targets and drug resistance. Furthermore, the increasing prevalence of cancer drug resistance poses a substantial challenge in the management of the disease. Henceforth, molecular alterations have become highly attractive drug targets to reverse the aberrant effects of miRNAs and splicing events that promote malignancy and drug resistance. While the miRNA-mRNA splicing interplay in cancer drug resistance remains largely to be elucidated, this review focuses on miRNA and alternative mRNA splicing (AS) events in breast, cervical, prostate, colorectal and ovarian cancer, as well as leukemia, and the role these events play in drug resistance. MiRNA induced cancer drug resistance; alternative mRNA splicing (AS) in cancer drug resistance; the interplay between AS and miRNA in chemoresistance will be discussed. Despite this great potential, the interplay between aberrant splicing events and miRNA is understudied but holds great potential in deciphering miRNA-mediated drug resistance.

Identification of Circular RNAs Associated With Chemoresistance in Colorectal Cancer

Chemoresistance is a major clinical obstacle for the treatment of colorectal cancer (CRC). Circular RNAs (circRNAs) are a new type of non-coding RNA that participated in the development of chemoresistance. However, the profiles and effects of circRNAs in 5-fluorouracil (5-Fu) and cisplatin resistance of CRC are still unclear and need to be elucidated. In the present study, the profiles of circRNAs in CRC chemoresistant (HCT8/5-Fu and HCT8/DDP) and chemosensitive (HCT8) cell lines were identified via RNA-sequencing. In total, 48 and 90 differentially expressed (DE)-circRNAs were detected in HCT8/5-Fu and HCT8/DDP cell lines, respectively. Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analysis were conducted on the host genes of DE-circRNAs; the results showed that the most significant enrichment pathways in HCT8/5-Fu and HCT8/DDP cell lines were base excision repair and Hippo signaling pathway, respectively. In addition, 11 common DE-circRNAs in the two drug-resistant cell lines (two are upregulated and nine are downregulated) were screened and verified by quantitative real-time PCR; hsacirc_023607 and hsacirc_007420 were found to be the circRNAs with the highest upregulation and downregulation fold changes. However, functional studies showed hsacirc_023607 has no effect on CRC chemoresistance. Therefore, the regulatory networks of targeted miRNAs related to 5-Fu or cisplatin resistance were predicted and constructed, in which hsacirc_002482 was identified as a hub gene, and its overexpression could suppress HCT8/5-Fu and HCT8/DDP cell proliferation and promote cell apoptosis, and enhance cell chemosensitivity. Taken together, these results of the study suggested that hsacirc_002482 may play important roles in chemoresistance of CRC.

Screening and Bioinformatics Analysis of Competitive Endogenous RNA Regulatory Network --Related to Circular RNA in Breast Cancer

Purpose

Circular RNA as a competitive endogenous RNA (ceRNA) plays a significant role in the pathogenesis and progression of breast cancer. In this study, a circular RNA-related ceRNA regulatory network was constructed, which provides new biomarkers and therapeutic targets for the treatment of breast cancer. Materials and methods. The expression profile datasets (GSE101123, GSE143564, GSE50428) of circRNAs, miRNAs, and mRNAs were downloaded from the GEO database, and then differentially expressed RNAs (DEcircRNAs, DEmiRNAs, DEmRNAs) were obtained through the CSCD, TargetScan, miRDB, and miRTarBase databases. CircRNA-miRNA pairs and miRNA-mRNA pairs were constructed. Finally, a ceRNA regulatory network was established. Downstream analysis of the ceRNA network included GO, KEGG analysis, survival analysis, sub-network construction, the BCIP, and qRT-PCR verification.

Results

In total, 144 differentially expressed (DE) DEcircRNA, 221 DEmiRNA, and 1211 DEmRNA were obtained, and 96 circRNA-miRNA pairs and 139 miRNA-mRNA pairs were constructed by prediction. The ceRNA regulatory network (circRNA-miRNA-mRNA) was constructed, which included 42 circRNA, 36miRNA, and 78 mRNA. GO function annotation showed genes were mainly enriched in receptor activity activated by transforming growth factor beta (TGF-beta) and in the regulation of epithelial cell apoptosis. KEGG analysis showed genes were mainly enriched in the TGF-beta signaling, PI3K-Akt signaling, and Wnt signaling pathways. Four genes associated with survival and prognosis of breast cancer were obtained by survival analysis, the prognostic sub-network included 4 circRNA, 4 miRNA, and 4 mRNA. BCIP analysis and qRT-PCR verification confirmed that relative mRNA expression levels were consistent with those in the GEO database.

Conclusion

A circRNA-related ceRNA regulatory network was constructed for breast cancer in this study and key genes affecting pathogenesis and progression were identified. These findings may help better understand and further explore the molecular mechanisms that affect the progression and pathogenesis of breast cancer.

Extracellular-vesicle containing miRNA-503-5p released by macrophages contributes to atherosclerosis

Endothelial dysfunction, and the differentiation of smooth muscle cells (SMCs) into proliferative, secretory phenotypes, are two major pathophysiological processes in atherosclerosis. SMCs have the potential to recruit macrophages in atherosclerotic plaques, in which macrophages drive inflammatory responses. In this study, we found that microRNA-503-5p (miR-503-5p) was enriched in either extracellular vesicles (EVs), secreted by oxidized low-density lipoprotein-treated macrophages, or the EVs from peripheral blood mononuclear cells of atherosclerosis patients. miR-503-5p was transferred intercellularly from macrophages to the co-cultured human coronary artery endothelial cells (HCAECs) and HCASMCs via EVs, thus reducing the proliferative and angiogenic abilities of HCAECs and accelerating the proliferative and migrating abilities of HCASMCs. Smad family members 1, 2 and 7 were negatively regulated by miR-503-5p in HCAECs and HCASMCs. miR-503-5p was verified as an enhancer of inflammatory cytokines and adhesion molecules released by macrophages, in part via the down-regulation of smad family members 1, 2 and 7. The inhibition of miR-503-5p by lentivirus reduced atherosclerotic lesion formations in the aorta of atherosclerotic mice. Our work demonstrated a miR-503-5p- and EV-mediated mechanism for macrophage communication with HCAECs and HCASMCs in atherosclerosis. miR-503-5p is pro-atherosclerotic stimuli that may be a therapeutic target for atherosclerosis treatment.

HDAC2 interacts with microRNA-503-5p to regulate SGK1 in osteoarthritis

Background

Osteoarthritis (OA) is a disabling joint disease that causes articular cartilage degeneration. It has been implicated that altered expression of histone deacetylase 2 (HDAC2) is found in patients with OA. However, the specific role of HDAC2 in the development of OA still remains enigmatic. Hence, we sought to characterize the functional relevance of HDAC2 in the development of OA.

Methods

Anterior cruciate ligament surgery was performed to generate the rat model of OA. Luciferase assay was performed to evaluate the relationship between microRNA-503-5p (miR-503-5p) and serum- and glucocorticoid-inducible kinase-1 (SGK1). Functional experiments were conducted to examine the functional significance of miR-503-5p, histone deacetylase 2 (HDAC2), and SGK1 on the progression of OA by determining proliferation, apoptosis, and expression of apoptosis-associated proteins and inflammatory cytokines.

Results

HDAC2 could inhibit miR-503-5p expression. SGK1 was the target gene of miR-503-5p. Upregulation of miR-503-5p or silencing of HDAC2 contributed to enhanced proliferation, suppressed apoptosis (reduced expression of Caspase-3 and Bax but elevated expression of Bcl2), and promoted inflammation in chondrocytes of OA rats.

Conclusion

In conclusion, our study demonstrated that HDAC2 could promote OA through miR-503-5p/SGK1 axis, which might function as a therapeutic target for OA treatment.

MicroRNA-Based Therapeutics for Drug-Resistant Colorectal Cancer

Although therapeutic approaches for patients with colorectal cancer (CRC) have improved in the past decades, the problem of drug resistance still persists and acts as a major obstacle for effective therapy. Many studies have shown that drug resistance is related to reduced drug uptake, modification of drug targets, and/or transformation of cell cycle checkpoints. A growing body of evidence indicates that several microRNAs (miRNAs) may contribute to the drug resistance to chemotherapy, targeted therapy, and immunotherapy by regulating the drug resistance-related target genes in CRC. These drug resistance-related miRNAs may be used as promising biomarkers for predicting drug response or as potential therapeutic targets for treating patients with CRC. In this review, we summarized the recent discoveries regarding anti-cancer drug-related miRNAs and their molecular mechanisms in CRC. Furthermore, we discussed the challenges associated with the clinical application of miRNAs as biomarkers for the diagnosis of drug-resistant patients and as therapeutic targets for CRC treatment.

Dihydromyricetin reverses MRP2-induced multidrug resistance by preventing NF-κB-Nrf2 signaling in colorectal cancer cell

BACKGROUD

Dihydromyricetin (DMY), a natural flavonoid compound from the leaves of the Chinese medicinal herb Vitis heyneana, has been shown to have the potential to combat chemoresistance by inhibiting Nrf2/MRP2 signaling in colorectal cancer (CRC) cells. However, the precise underlying molecular mechanism and its therapeutic target are not well understood.

PURPOSE

Our study aims to investigate the effects of DMY on multidrug resistance (MDR), and elucidate the underlying mechanisms.

STUDY DESIGN

In vitro, HCT116/OXA and HCT8/VCR cells were employed as our MDR models. The cells were treated with DMY (50 µM) or MK-571 (50 µM) plus oxaliplatin (OXA) (10 µM) or vincristine (VCR) (10 µM) for 48 h. In vivo, we used BALB/c mice as a CRC xenograft mouse model. BALB/c mice were given DMY (100 mg/kg), OXA (5 mg/kg) and DMY (100 mg/kg) combined with OXA (5 mg/kg) via intraperitoneal route every 2 days per week for 4 weeks.

METHODS

We used MTT and colony forming assays to detect DMY's ability to reverse MDR. Flow cytometric analysis was used to detect apoptosis. Immunocytochemistry was used to detect the localization of Nrf2 and NF-κB/p65. Western blot, qRT-PCR and reporter gene assays were employed to measure the protein and gene transcriptional levels (MRP2, Nrf2, NF-κB/p65). Moreover, chromatin immunoprecipitation (ChIP) assay was used to investigate the endogenous promoter occupancy of NF-κB/p65. Finally, immunohistochemistry and TUNEL staining were used to detect protein expression and apoptosis in vivo.

RESULTS

DMY restored chemosensitivity (OXA and VCR) by inhibiting both MRP2 expression and its promoter activity in HCT116/OXA and HCT8/VCR cell lines. Furthermore, DMY could inhibit NF-κB/p65 expression, reducing NF-κB/p65 translocation to the nucleus to silence Nrf2 signaling, which is necessary for MRP2 expression. Overexpressing NF-κB/p65 expression reduced the reversal effect of DMY. In addition, NF-κB/p65 regulated Nrf2 expression by directly binding to its specific promoter region and activating its transcription. Finally, we proved that the combination of OXA and DMY has a synergistic tumor suppression effect in vivo.

CONCLUSION

Our study provided a novel mechanism of DMY boosted chemosensitivity in human CRC. The downstream signals of DMY, NF-κB or Nrf2 could also be potential targets for the treatment of CRC.

Flavonoid display ability to target microRNAs in cancer pathogenesis

MicroRNAs (miRNAs) are non-coding, conserved, single-stranded nucleotide sequences involved in physiological and developmental processes. Recent evidence suggests an association between miRNAs' deregulation with initiation, promotion, progression, and drug resistance in cancer cells. Besides, miRNAs are known to regulate the epithelial-mesenchymal transition, angiogenesis, autophagy, and senescence in different cancer types. Previous reports proposed that apart from the antioxidant potential, flavonoids play an essential role in miRNAs modulation associated with changes in cancer-related proteins, tumor suppressor genes, and oncogenes. Thus, flavonoids can suppress proliferation, help in the development of drug sensitivity, suppress metastasis and angiogenesis by modulating miRNAs expression. In the present review, we summarize the role of miRNAs in cancer, drug resistance, and the chemopreventive potential of flavonoids mediated by miRNAs. The potential of flavonoids to modulate miRNAs expression in different cancer types demonstrate their selectivity and importance as regulators of carcinogenesis. Flavonoids as chemopreventive agents targeting miRNAs are extensively studied in vitro, in vivo, and pre-clinical studies, but their efficiency in targeting miRNAs in clinical studies is less investigated. The evidence presented in this review highlights the potential of flavonoids in cancer prevention/treatment by regulating miRNAs, although further investigations are required to validate and establish their clinical usefulness.

The microRNA-424/503 cluster: A master regulator of tumorigenesis and tumor progression with paradoxical roles in cancer

MicroRNAs (miRNAs) are a group of non-coding RNAs that play a crucial role in post-transcriptional gene regulation and act as indispensable mediators in several critical biological processes, including tumorigenesis, tissue homeostasis, and regeneration. MiR-424 and miR-503 are intragenic miRNAs that are clustered on human chromosome Xq26.3. Previous studies have reported that both miRNAs are dysregulated and play crucial but paradoxical roles in tumor initiation and progression, involving different target genes and molecular pathways. Moreover, these two miRNAs are concomitantly expressed in several cancer cells, indicating a coordinating function as a cluster. In this review, the roles and regulatory mechanisms of miR-424, miR-503, and miR-424/503 cluster are summarized in different types of cancers.

Molecular mechanisms and clinical implications of miRNAs in drug resistance of colorectal cancer

Systemic chemotherapy is identified as a curative approach to prolong the survival time of patients with colorectal cancer (CRC). Although great progress in therapeutic approaches has been achieved during the last decades, drug resistance still extensively persists and serves as a major hurdle to effective anticancer therapy for CRC. The mechanism of multidrug resistance remains unclear. Recently, mounting evidence suggests that a great number of microRNAs (miRNAs) may contribute to drug resistance in CRC. Certain of these miRNAs may thus be used as promising biomarkers for predicting drug response to chemotherapy or serve as potential targets to develop personalized therapy for patients with CRC. This review mainly summarizes recent advances in miRNAs and the molecular mechanisms underlying miRNA-mediated chemoresistance in CRC. We also discuss the potential role of drug resistance-related miRNAs as potential biomarkers (diagnostic and prognostic value) and envisage the future orientation and challenges in translating the findings on miRNA-mediated chemoresistance of CRC into clinical applications.

Cellular Mechanisms Accounting for the Refractoriness of Colorectal Carcinoma to Pharmacological Treatment

Simple Summary

Colorectal cancer (CRC) causes a high number (more than 800,000) of deaths worldwide each year. Better methods for early diagnosis and the development of strategies to enhance the efficacy of the therapeutic approaches used to complement or substitute surgical removal of the tumor are urgently needed. Currently available pharmacological armamentarium provides very moderate benefits to patients due to the high resistance of tumor cells to respond to anticancer drugs. The present review summarizes and classifies into seven groups the cellular and molecular mechanisms of chemoresistance (MOC) accounting for the failure of CRC response to the pharmacological treatment.

Abstract

The unsatisfactory response of colorectal cancer (CRC) to pharmacological treatment contributes to the substantial global health burden caused by this disease. Over the last few decades, CRC has become the cause of more than 800,000 deaths per year. The reason is a combination of two factors: (i) the late cancer detection, which is being partially solved by the implementation of mass screening of adults over age 50, permitting earlier diagnosis and treatment; (ii) the inadequate response of advanced unresectable tumors (i.e., stages III and IV) to pharmacological therapy. The latter is due to the existence of complex mechanisms of chemoresistance (MOCs) that interact and synergize with each other, rendering CRC cells strongly refractory to the available pharmacological regimens based on conventional chemotherapy, such as pyrimidine analogs (5-fluorouracil, capecitabine, trifluridine, and tipiracil), oxaliplatin, and irinotecan, as well as drugs targeted toward tyrosine kinase receptors (regorafenib, aflibercept, bevacizumab, cetuximab, panitumumab, and ramucirumab), and, more recently, immune checkpoint inhibitors (nivolumab, ipilimumab, and pembrolizumab). In the present review, we have inventoried the genes involved in the lack of CRC response to pharmacological treatment, classifying them into seven groups (from MOC-1 to MOC-7) according to functional criteria to identify cancer cell weaknesses. This classification will be useful to pave the way for developing sensitizing tools consisting of (i) new agents to be co-administered with the active drug; (ii) pharmacological approaches, such as drug encapsulation (e.g., into labeled liposomes or exosomes); (iii) gene therapy interventions aimed at restoring the impaired function of some proteins (e.g., uptake transporters and tumor suppressors) or abolishing that of others (such as export pumps and oncogenes).

Controlled pharmacokinetic anti-cancer drug concentration profiles lead to growth inhibition of colorectal cancer cells in a microfluidic device

We present a microfluidic device to expose cancer cells to a dynamic, in vivo-like concentration profile of a drug, and quantify efficacy on-chip. About 30% of cancer patients receive drug therapy. In conventional cell culture experiments drug efficacy is tested under static concentrations, e.g. 1 μM for 48 hours, whereas in vivo, drug concentration follows a pharmacokinetic profile with an initial peak and a decline over time. With the rise of microfluidic cell culture models, including organs-on-chips, there are opportunities to more realistically mimic in vivo-like concentrations. Our microfluidic device contains a cell culture chamber and a drug-dosing channel separated by a transparent membrane, to allow for shear stress-free drug exposure and label-free growth quantification. Dynamic drug concentration profiles in the cell culture chamber were controlled by continuously flowing controlled concentrations of drug in the dosing channel. The control over drug concentrations in the cell culture chambers was validated with fluorescence experiments and numerical simulations. Exposure of HCT116 colorectal cancer cells to static concentrations of the clinically used drug oxaliplatin resulted in a sensible dose-effect curve. Dynamic, in vivo-like drug exposure also led to statistically significant lower growth compared to untreated control. Continuous exposure to the average concentration of the in vivo-like exposure seems more effective than exposure to the peak concentration (Cmax) only. We expect that our microfluidic system will improve efficacy prediction of in vitro models, including organs-on-chips, and may lead to future clinical optimization of drug administration schedules.

Circ_0010220-mediated miR-503-5p/CDCA4 axis contributes to osteosarcoma progression tumorigenesis

CircRNAs are reported to exert a significant role in modulating genes in cancers, including osteosarcoma progression. Up to now, the function of circ_0010220 in osteosarcoma is still poorly known. The aim of our work was to figure out the potential mechanism of circ_0010220/miR-503-5p/CDCA4 axis in osteosarcoma progression. Firstly, quantitative RT-qPCR was utilized to measure the expression of circ_0010220 in osteosarcoma cells. Then, osteosarcoma cell proliferation, apoptosis, cell cycle, migration and invasion after loss of circ_0010220 were evaluated using CCK-8, flow cytometry, transwell migration, invasion and tumorigenesis experiments respectively. Circ_0010220 expression was markedly increased in osteosarcoma cells. Additionally, knockdown of circ_0010220 significantly depressed tumor growth. CCK-8 analysis indicated that down-regulation of circ_0010220 inhibited osteosarcoma cells proliferation. Flow cytometry assay showed that knockdown of circ_0010220 induced cell apoptosis and blocked cell cycle in the G1 phase. Meanwhile, cell migration an invasion was reduced by circ_0010220. Furthermore, miR-503-5p was predicted as the target for circ_0010220 and miR-503-5p inhibitors reversed cell growth suppressed through silencing circ_0010220. Then, our study demonstrated that Cell Division Cycle-Associated protein 4 (CDCA4) could be a downstream target of miR-503-5p. Additionally, circ_0010220 down-regulation reduced CDCA4 expression level and the inhibitors of miR-503-5p reversed that. In conclusion, we indicated circ_0010220 can be an important biomarker for osteosarcoma via regulating miR-503-5p and CDCA4.

GOLPH3 inhibition reverses oxaliplatin resistance of colon cancer cells via suppression of PI3K/AKT/mTOR pathway

OBJECTIVE

To explore whether GOLPH3 regulated oxaliplatin (L-OHP) resistance of colon cancer cells via PI3K/AKT/mTOR pathway.

METHODS

HCT116/L-OHP cells were divided into Blank, Control/GOLPH3 shRNA, BEZ235 (a PI3K/AKT/mTOR inhibitor), and GOLPH3 + BEZ235 groups followed by the detection with MTT, soft agar colony formation, flow cytometry and TUNEL assays. Mice bearing HCT116/L-OHP xenografts were randomized into Control, L-OHP, NC/GOLPH3 shRNA, L-OHP + NC/GOLPH3 shRNA groups. The expressions of Ki67, Caspase-3, and PI3K/AKT/mTOR pathway proteins were examined by immunohistochemistry.

RESULTS

HCT116/L-OHP cells had increased GOLPH3 expression compared to HCT116 cells, which positively regulated PI3K/AKT/mTOR pathway in HCT116/L-OHP cells. BEZ235 declined IC50 of HCT116/L-OHP cells to L-OHP, decreased the expressions of ABCB1, ABCC1, ABCG2, ATP7A, ATP7B, MATE1, p-gp, MRP1 and BCRP, induced cell apoptosis, reduced cell proliferation, and arrested cells at G0/G1, which was reversed by GOLPH3 overexpression. L-OHP and GOLPH3 shRNA decreased tumor volume and reduced expression of Ki67 in tumor tissues with the increased Caspase-3. Meanwhile, the combined treatment had the better treatment effect.

CONCLUSION

GOLPH3 inhibition reduced proliferation and promoted apoptosis of HCT116/L-OHP cells, and also reversed the L-OHP resistance of HCT116/L-OHP, which may be associated with the suppression of P13K/AKT/mTOR pathway.

hsa_circ_0072387 Suppresses Proliferation, Metastasis, and Glycolysis of Oral Squamous Cell Carcinoma Cells by Downregulating miR-503-5p

Background: Oral squamous cell carcinoma (OSCC) is the most common malignant tumor of the oral cavity. It was determined that circular RNAs were related to the development and progression of various cancers, including OSCC. The purpose of our study was to define the role and potential mechanism of hsa_circ_0072387 in OSCC progression. Materials and Methods: Thirty-five patients with OSCC were involved in this study. Real-time quantitative polymerase chain reaction was used to evaluate the expression levels of hsa_circ_0072387 and microRNA (miR)-503-5p. Cell proliferation, migration, and invasion abilities were assessed by Cell Counting Kit-8 (CCK-8) and Transwell assays, respectively. The abundance of cell proliferation marker Ki-67, epithelial-mesenchymal transition (EMT) markers E-cadherin, N-cadherin, and vimentin was analyzed by Western blot assay. Glycolysis was evaluated using commercial kits. The interaction between hsa_circ_0072387 and miR-503-5p was confirmed by bioinformatics analysis, RNA immunoprecipitation (RIP) assay, and dual-luciferase reporter assay. Results: hsa_circ_0072387 expression was significantly downregulated, and miR-503-5p was upregulated in OSCC cells and tissues. Gain of hsa_circ_0072387 or knockdown of miR-503-5p suppressed the cell proliferation, migration and invasion, EMT, and glycolysis in OSCC SCC-4 and HSC-3 cells. hsa_circ_0072387 targeted miR-503-5p and inversely regulated miR-503-5p expression. Moreover, upregulation of miR-503-5p could partially revert the tumor-suppressive effects of hsa_circ_0072387 on OSCC cells. Conclusion: hsa_circ_0072387 inhibited OSCC progression by downregulating miR-503-5p, explicating that hsa_circ_0072387 could function as a novel potential therapeutic target for OSCC.

MicroRNA-663b enhances migration and invasion by targeting adenomatous polyposis coli 2 in colorectal carcinoma cells

Colorectal carcinoma (CRC) is one of the leading causes of cancer-associated mortality worldwide. Dysregulation of microRNA (miR)-663b has been reported in a variety of diseases. However, the specific biological function of miR-663b in CRC requires further investigation. The aim of the present study was to elucidate the role and underlying molecular mechanism of action of miR-663b in CRC. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis and western blot analysis were employed to measure the expression of miR-663b at the RNA and protein level, respectively. Flow cytometry was used to detect cell apoptosis. Cell proliferation, migration and invasion were evaluated by the Cell Counting Kit-8, wound healing and Transwell assays, respectively. A dual-luciferase reporter assay was used to validate the potential target gene of miR-663b. The expression of miR-663b was identified to be markedly upregulated in CRC cells. Ectopic miR-663b expression promoted CRC cell proliferation, migration and invasion, and inhibited apoptosis. The dual-luciferase reporter assay identified adenomatous polyposis coli 2 (APC2) as a direct target of miR-663b in CRC cells. Further investigation indicated that miR-663b was involved in CRC cell invasion through the Wnt/β-catenin pathway. Therefore, overexpression of miR-663b was able to promote CRC cell proliferation, migration and invasion by regulating the Wnt/β-catenin pathway through targeting APC2, suggesting that miR-663b may be a useful target for the diagnosis and treatment of CRC.

β-Sitosterol Reverses Multidrug Resistance via BCRP Suppression by Inhibiting the p53-MDM2 Interaction in Colorectal Cancer

Phytosterols are widely present in vegetable oils, nuts, cereal products, fruits, and berries. Phytosterol-induced treatment sensitivity has recently shed light on alleviating multidrug resistance in cancer therapy. Here, we demonstrated that β-sitosterol, the most common dietary phytosterol, recovers oxaliplatin (OXA) sensitivity in drug-resistant colorectal cancer (CRC) cells by inhibiting breast cancer resistance protein (BCRP) expression. We further showed evidence that β-sitosterol could activate p53 by disrupting the p53-MDM2 interaction, leading to an increase in p53 translocation to the nucleus and silencing the nuclear factor-κB (NF-κB) pathway, which is necessary for BCRP expression. Finally, we suggested that the combination of OXA and β-sitosterol has a synergistic tumor suppression effect in vivo using a xenograft mouse model. These results revealed that β-sitosterol is able to mediate the p53/NF-κB/BCRP signaling axis to regulate the response of CRC to chemotherapy. The combined application of β-sitosterol and OXA can be a potential way to improve CRC treatment.

Targeting CD133 reverses drug-resistance via the AKT/NF-κB/MDR1 pathway in colorectal cancer

BACKGROUND

Recent studies have shown that multidrug resistance may be induced by the high stemness of cancer cells. Following prolonged chemotherapy, MDR protein 1 (MDR1) and CD133 increase in CRC, but the relationship between them is unclear.

METHODS

The relationship between MDR and CSC properties in CRC was determined via CCK-8 assay, apoptosis assay, DOX uptake and retention, immunohistochemistry, immunofluorescence and flow cytometry. The correlations between their expression levels were evaluated using Spearman's rank statistical test and the Mann-Whitney test. Furthermore, the effect of CD133 on the repression of the AKT/NF-κB/MDR1 signalling pathway was investigated in vitro and in vivo.

RESULTS

We found that CD133 increased with the emergence of drug-resistance phenotypes, and the high expression of MDR1/P-gp was consistently accompanied by positive expression of CD133 as demonstrated by the analysis of patient samples. Up- or downregulation of CD133 could regulate MDR via AKT/NF-κB/MDR1 signalling in CRC. A rescue experiment showed that the AKT/NF-κB signalling pathway is the main mechanism by which CD133 regulates MDR1/P-gp expression in CRC.

CONCLUSIONS

Taken together, our results suggest that targeting CD133 reverses drug resistance via the AKT/NF-κB/MDR1 pathway and that this pathway might serve as a potential therapeutic target to reverse MDR in CRC.

MIR210HG promotes cell proliferation and invasion by regulating miR-503-5p/TRAF4 axis in cervical cancer

Long non-coding RNAs (lncRNAs) play important roles in the progression of cervical cancer (CC). However, the roles and underlying molecular mechanisms of lncRNAs in CC remain unclear. In the current study, we discovered a new lncRNA MIR210HG which was upregulated in CC tissues through microarray. The upregulation of MIR210HG was associated with advanced FIGO stage, metastasis, and poor prognosis in CC patients. Function assays showed that MIR210HG inhibition significantly suppressed the proliferation, invasion, and epithelial-mesenchymal transition (EMT) processes in CC and reduced tumor growth in vivo. Mechanistically, we identified that MIR210HG might serve as a competing endogenous RNA (ceRNA) of miR-503-5p to relieve the repressive effect of miR-503-5p on TRAF4 expression in CC cells. In conclusion, we demonstrated that MIR210HG promoted CC progression through regulating the MIR210HG/miR-503-5p/TRAF4 axis, indicating that MIR210HG might act as a novel insight into CC treatment.

Long Non-Coding RNA LINC00525 Promotes the Stemness and Chemoresistance of Colorectal Cancer by Targeting miR-507/ELK3 Axis

Background and Objectives

This study aims to explore the effects of a long non-coding RNA, LINC00525, on colorectal cancer (CRC) and its underlying molecular mechanisms.

Methods

The qPCR, MTT, colony formation, Western blotting, Luciferase reporter and biotin pull-down, shRNA knockdown and DNA fragmentation assays were performed in this study.

Results

High expressions of LINC00525 were associated with poor prognosis of CRC patients. LINC00525 knockdown decreased stemness properties and increased sensitivities to oxaliplatin. MiR-507 was a direct target of LINC00525 and overexpression of miR-507 significantly decreased abilities of tumorsphere formation and cell growth. Overexpression of miR-507 resulted in a decrease of expression of cancer stem cell markers and the increase of apoptosis rates. MiR-507 regulated the expression of ELK3. In addition, LINC00525 knockdown decreased the expression of ELK3. Restoration of ELK3 expression abrogated the effects of LINC00525 knockdown. LINC00525 could be served as prognostic marker of CRC.

Conclusions

LINC00525 enhanced stemness properties and increased sensitivities of CRC cells to oxaliplatin by targeting miR-507/ELK3 axis.

miR-126-3p down-regulation contributes to dabrafenib acquired resistance in melanoma by up-regulating ADAM9 and VEGF-A

Background

Development of resistance to inhibitors of BRAF (BRAFi) and MEK (MEKi) remains a great challenge for targeted therapy in patients with BRAF-mutant melanoma. Here, we explored the role of miRNAs in melanoma acquired resistance to BRAFi.

Methods

miRNA expression in two BRAF-mutant melanoma cell lines and their dabrafenib-resistant sublines was determined using Affymetrix GeneChip® miRNA 3.1 microarrays and/or qRT-PCR. The effects of miR-126-3p re-expression on proliferation, apoptosis, cell cycle, ERK1/2 and AKT phosphorylation, dabrafenib sensitivity, invasiveness and VEGF-A secretion were evaluated in the dabrafenib-resistant sublines using MTT assays, flow cytometry, immunoblotting, invasion assays in Boyden chambers and ELISA. ADAM9, PIK3R2, MMP7 and CXCR4 expression in the sensitive and dabrafenib-resistant cells was determined by immunoblotting. Small RNA interference was performed to investigate the consequence of VEGFA or ADAM9 silencing on proliferation, invasiveness or dabrafenib sensitivity of the resistant sublines. Long-term proliferation assays were carried out in dabrafenib-sensitive cells to assess the effects of enforced miR-126-3p expression or ADAM9 silencing on resistance development. VEGF-A serum levels in melanoma patients treated with BRAFi or BRAFi+MEKi were evaluated at baseline (T0), after two months of treatment (T2) and at progression (TP) by ELISA.

Results

miR-126-3p was significantly down-regulated in the dabrafenib-resistant sublines as compared with their parental counterparts. miR-126-3p replacement in the drug-resistant cells inhibited proliferation, cell cycle progression, phosphorylation of ERK1/2 and/or AKT, invasiveness, VEGF-A and ADAM9 expression, and increased dabrafenib sensitivity. VEGFA or ADAM9 silencing impaired proliferation and invasiveness of the drug-resistant sublines. ADAM9 knock-down in the resistant cells increased dabrafenib sensitivity, whereas miR-126-3p enforced expression or ADAM9 silencing in the drug-sensitive cells delayed the development of resistance. At T0 and T2, statistically significant differences were observed in VEGF-A serum levels between patients who responded to therapy and patients who did not. In responder patients, a significant increase of VEGF-A levels was observed at TP versus T2.

Conclusions

Strategies restoring miR-126-3p expression or targeting VEGF-A or ADAM9 could restrain growth and metastasis of dabrafenib-resistant melanomas and increase their drug sensitivity. Circulating VEGF-A is a promising biomarker for predicting patients’ response to BRAFi or BRAFi+MEKi and for monitoring the onset of resistance.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1238-4) contains supplementary material, which is available to authorized users.

Current Evidence on miRNAs as Potential Theranostic Markers for Detecting Chemoresistance in Colorectal Cancer: A Systematic Review and Meta-Analysis of Preclinical and Clinical Studies

BACKGROUND

Findings from observational clinical studies examining the relationship between biomarker expression and theranosis in colorectal cancer (CRC) have been conflicting.

OBJECTIVE

We conducted this systematic review and meta-analysis to summarise the existing evidence to demonstrate the involvement of microRNAs (miRNAs) in chemoresistance and sensitivity in CRC through drug genetic pathways.

METHODS

Using PRISMA guidelines, we systematically searched PubMed and Science Direct for relevant studies that took place between 2012 and 2017. A random-effects model of meta-analysis was applied to evaluate the pooled effect size of hazard ratios (HRs) across the included studies. Cochran's Q test and the I² statistic were used to detect heterogeneity. A funnel plot was used to assess potential publication bias.

RESULTS

Of the 4700 studies found, 39 studies comprising 2822 patients with CRC met the inclusion criteria. The included studies used one or a combination of 14 chemotherapy drugs, including 5-fluorouracil and oxaliplatin. Of the 60 miRNAs, 28 were associated with chemosensitivity, 20 with chemoresistance, and one with differential expression and radiosensitivity; ten miRNAs were not associated with any impact on chemotherapy. The results outline the importance of 34 drug-regulatory pathways of chemoresistance and sensitivity in CRC. The mean effect size was 0.689 (95% confidence interval 0.428-1.110), indicating that the expression of miRNAs decreased the likelihood of death by about 32%.

CONCLUSION

Studies have consistently shown that multiple miRNAs could act as clinical predictors of chemoresistance and sensitivity. An inclusion of supplementary miRNA estimation in CRC routine practice needs to be considered to evaluate the efficacy of chemotherapy after confirming our findings with large-scale prospective cohort studies.

PROSPERO REGISTRATION NUMBER

CRD42017082196.

Interactions among lncRNAs, miRNAs and mRNA in colorectal cancer

Long non-coding RNAs (lncRNAs) are longer than 200 nts non-coding transcripts and have recently emerged as one of the largest and significantly diverse RNA families whereas microRNAs (miRNAs) are highly conserved short single-stranded ncRNAs (∼18-22 nucleotides). As families of small and long evolutionarily conserved ncRNAs, lncRNAs activate and repress genes via a variety of mechanisms at both transcriptional and translational levels, while miRNAs regulate protein-coding gene expression mainly through mRNA degradation or silencing, These ncRNAs have been proved to be involved in multiple biological functions, such as proliferation, differentiation, migration, angiogenesis and apoptosis. Today, while majority of studies have focused on defining the regulatory functions of lncRNAs and miRNAs, limited information have now available for the mutual regulations of lncRNAs, miRNAs and mRNA. Thus, the underlying molecular mechanisms, in particularly the interactions among lncRNAs, miRNAs and mRNA in development, growth, metastasis and therapeutic potential of cancer still remain obscure. Colorectal cancer (CRC) is known as the third most common and fourth leading cancer death worldwide. Increasing evidence showed the close correlations among aberrant expressions of lncRNAs, miRNAs and the occurrence, development of CRC. This review summarize the potential links among these RNAs in following three areas: 1, The biogenesis and roles of miRNAs in CRC; 2, The biogenesis and functions of lncRNAs in CRC; 3, The interactions among lncRNAs, miRNAs and mRNA in tumorigensis, growth, progression, EMT formation, chemoradiotherapy resistance, and therapeutic potential in CRC. We believe that identifying diverging lncRNAs, miRNAs and relevant genes, their interactions and complex molecular regulatory networks will provide important clues for understanding the mechanism and developing novel diagnostic and therapeutic strategies for CRC. Further efforts are warranted to bring the promise of regulating their activities into clinical utilities.

The role and mechanisms of action of microRNAs in cancer drug resistance

MicroRNAs (miRNAs) are small non-coding RNAs with a length of about 19–25 nt, which can regulate various target genes and are thus involved in the regulation of a variety of biological and pathological processes, including the formation and development of cancer. Drug resistance in cancer chemotherapy is one of the main obstacles to curing this malignant disease. Statistical data indicate that over 90% of the mortality of patients with cancer is related to drug resistance. Drug resistance of cancer chemotherapy can be caused by many mechanisms, such as decreased antitumor drug uptake, modified drug targets, altered cell cycle checkpoints, or increased DNA damage repair, among others. In recent years, many studies have shown that miRNAs are involved in the drug resistance of tumor cells by targeting drug-resistance-related genes or influencing genes related to cell proliferation, cell cycle, and apoptosis. A single miRNA often targets a number of genes, and its regulatory effect is tissue-specific. In this review, we emphasize the miRNAs that are involved in the regulation of drug resistance among different cancers and probe the mechanisms of the deregulated expression of miRNAs. The molecular targets of miRNAs and their underlying signaling pathways are also explored comprehensively. A holistic understanding of the functions of miRNAs in drug resistance will help us develop better strategies to regulate them efficiently and will finally pave the way toward better translation of miRNAs into clinics, developing them into a promising approach in cancer therapy.

MicroRNA expression profiling of adult hippocampal neural stem cells upon cell death reveals an autophagic cell death-like pattern

Adult hippocampal neural (HCN) stem cells promptly undergo irreversible autophagic cell death (ACD) if deprived of insulin in culture. Small, non-coding microRNAs (miRNA) play an important role in regulating biological processes, including proliferation and cell death. However, there have been no reports thus far regarding miRNA involvement in the induction of adult HCN stem cell death under insulin-deprived conditions, for which we performed a microarray-based analysis to examine the expression signature of miRNAs in adult rat HCN stem cells. Three independent specimens per culture condition either with or without insulin were prepared and a miRNA microarray analysis carried out. A total of 12 exhibited significantly altered expression levels upon cell death due to the absence of insulin when compared to HCN stem cells cultured with insulin present (cut-off limit; p < 0.05 and fold-change >1.3) The resulting volcano plot showed that, among these miRNAs, seven were upregulated and five were downregulated. The upregulated miRNAs were capable of modulating HCN stem cell death. Caspase-3 activity analysis, LC3 conversion, and TEM of autophagosome formation consistently suggested that ACD, not apoptosis, was most likely the mechanism affecting HCN cell death. As such, we have come to term these miRNAs, "HCN stem cell-specific autophagic cell death regulators." Taken together, our data suggest that the miRNA expression profile of HCN stem cells is altered during ACD occurring due to insulin deprivation and that differentially expressed miRNAs are involved in HCN stem cell viability. Detailed explorations of the underlying mechanisms regarding HCN stem cell viability modulation by these miRNAs would be beneficial in further understanding the physiological features of adult HCN stem cells and are currently being investigated.

CircHMGCS1 is upregulated in colorectal cancer and promotes proliferation of colorectal cancer cells by targeting microRNA-503-5p

This study aims to explore the regulatory mechanism of circHMGCS1/microRNA-503-5p (miR-503-5p) axis during colorectal cancer (CRC) development and progression. Real-time quantitative polymerase chain reaction (RT-qPCR) was applied to evaluate the expression of circHMGCS1 and miR-503-5p in CRC samples and their adjacent non-tumor specimen. Then, cell proliferation and cell apoptosis and migration and invasion of circHMGCS1-knocked down cells were further detected, using cell counting kit-8 (CCK-8), flow cytometry, Transwell assay, and western blotting assays. CircHMGCS1 was found to be significantly upregulated in CRC, and its high expression was closely correlated with the poor clinical parameter. In addition, the knockdown of circHMGCS1 could significantly inhibit CRC cells’ growth promoting apoptosis, as suggested by the expression of apoptosis pathway-related proteins, which changed consistently. Furthermore, miR-503-5p inhibitors were able to reverse the suppression of cell proliferation induced by silencing circHMGCS1. Therefore, circHMGCS1 might serve as a promising bio-marker and treatment target for CRC.

miR-122 enhances sensitivity of hepatocellular carcinoma to oxaliplatin via inhibiting MDR1 by targeting Wnt/β-catenin pathway

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the primary causes of cancer-related death and resistance to cytotoxic chemotherapy is the major cause of mortality in HCC patients. miR-122 is a liver specific miRNA and is found to be reduced in HCC, however, the function of miR-122 in HCC chemosensitivity remains elusive.

METHODS

We used qRT-PCR to measure expressions of miR-122, β-catenin and MDR1 in four HCC cell lines. And we assessed the effects of miR-122 or β-catenin on cell viability and apoptosis upon oxaliplatin (OXA) treatment by MTT assay and flow cytometry. In addition, we validated the interactions of miR-122/β-catenin and β-catenin/MDR1 by dual luciferase reporter assay and chromatin immunoprecipitation (ChIP). Western blotting was used to determine the protein levels of β-catenin, Wnt1 and MDR1. In the end, we verified the anti-tumor effect of miR-122 in vivo by using mouse tumor xenograft model.

RESULTS

We found that miR-122 was down-regulated in HCC cells. Up-regulation of miR-122 or inhibition of Wnt/β-catenin signaling promoted HCC cells apoptosis and increased the sensitivity of HCC cells to OXA. On the molecular level, we showed that miR-122 directly targeted and suppressed Wnt/β-catenin pathway while β-catenin bound with MDR1 promoter and activated its transcription. Overexpression of miR-122 inhibited MDR1 expression via directly suppressing Wnt/β-catenin pathway.

CONCLUSION

Our study fully demonstrated that miR-122 inhibits MDR1 expression via suppression of Wnt/β-catenin pathway, thereby enhancing HCC sensitivity to OXA. Therefore, miR-122 could serve as a novel potential therapeutic target for HCC.

MicroRNA-transcription factor network analysis reveals miRNAs cooperatively suppress RORA in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) represents over 90% of oral cancer incidence, while its mechanisms of tumorigenesis remain poorly characterized. In this study, we applied RNA-seq and microRNA-seq methodologies in four pairs of cancer and adjacent normal tissues to profile the contribution of miRNAs to tumorigenesis-altered functional pathways by constructing a comprehensive miRNA-mediated mRNA regulatory network. There were 213 differentially expressed (DE) miRNAs and 2172 DE mRNAs with the involvement of negative miRNA-mRNA interactions identified by at least two pairs of cancerous tissues. GO analysis revealed that the upregulated microRNAs significantly contributed to a global down-regulation of a number of transcription factors (TFs) in OSCC. Among the negative regulatory networks between the selected miRNAs (133) and TFs (167), circadian rhythm genes (RORA, RORB, RORC, and CLOCK) simultaneously regulated by multiple microRNAs were of particular interest. For instance, RORA transcript was predicted to be targeted by 25 co-upregulated miRNAs, of which, miR-503-5p, miR-450b-5p, miR-27a-3p, miR-181a-5p and miR-183-5p were further validated to directly target RORA, resulting in a stronger effect on RORA suppression together. In addition, we showed that the mRNA and protein expression levels of RORα were significantly decreased in most OSCC samples, associated with advanced clinical stage and poor prognosis. RORα significantly suppressed the proliferation of OSCC cells in vitro and in vivo. Attenuated RORα decreased p53 protein expression and suppressed p53 phosphorylation activity. Altogether, our results strongly suggest the importance of the role of miRNAs in regulating the activity of circadian rhythm-related TFs network during OSCC tumorigenesis, and provide further clues to understand the clinical link between circadian rhythm and cancer therapy.

Effects of miR-503-5p on apoptosis of human pulmonary microvascular endothelial cells in simulated microgravity

Recent studies have shown that microRNA (miRNAs) can play important roles in the regulation of endothelial cell (EC) function. However, the expression profile of miRNAs and their effects on the apoptosis of ECs under microgravity conditions remains unclear. In this study, the apoptosis of human pulmonary microvascular endothelial cells (HPMECs) under simulated microgravity was identified by Annexin V and propidium iodide double staining and transmission electron microscopy. miRNA microarray assay was used to screen the differentially expressed miRNAs in HPMECs under simulated microgravity, and eight differentially expressed miRNAs were identified. Specifically, miR-503-5p, which was found to be most significantly upregulated in both microarray and quantitative reverse-transcription polymerase chain reaction assays, was selected for further functional investigation. Overexpression of miR-503-5p induced apoptosis of HPMECs under normal gravity and aggravated the negative effects of simulated microgravity on HPMECs. Furthermore, silencing of miR-503-5p expression effectively attenuated the negative effects of simulated microgravity on HPMECs. Further experiments showed that the mRNA and protein expression of anti-apoptotic factor B-cell lymphoma-2 (Bcl-2), which has been confirmed as a direct target of miR-503-5p, was inhibited by the upregulation of miR-503-5p and increased by the downregulation of miR-503-5p. Taken together, our findings demonstrate, for the first time, that miR-503-5p can induce apoptosis of HPMECs under simulated microgravity through, at least in part, inhibiting the expression of Bcl-2.

Ipatasertib, a novel Akt inhibitor, induces transcription factor FoxO3a and NF-κB directly regulates PUMA-dependent apoptosis

Colon cancer is one of the three common malignant tumors, with a lower survival rate. Ipatasertib, a novel highly selective ATP-competitive pan-Akt inhibitor, shows a strong antitumor effect in a variety of carcinoma, including colon cancer. However, there is a lack of knowledge about the precise underlying mechanism of clinical therapy for colon cancer. We conducted this study to determine that ipatasertib prevented colon cancer growth through PUMA-dependent apoptosis. Ipatasertib led to p53-independent PUMA activation by inhibiting Akt, thereby activating both FoxO3a and NF-κB synchronously that will directly bind to PUMA promoter, up-regulating PUMA transcription and Bax-mediated intrinsic mitochondrial apoptosis. Remarkably, Akt/FoxO3a/PUMA is the major pathway while Akt/NF-κB/PUMA is the secondary pathway of PUMA activation induced by ipatasertib in colon cancer. Knocking out PUMA eliminated ipatasertib-induced apoptosis both in vitro and in vivo (xenografts). Furthermore, PUMA is also indispensable in combinational therapies of ipatasertib with some conventional or novel drugs. Collectively, our study demonstrated that PUMA induction by FoxO3a and NF-κB is a critical step to suppress the growth of colon cancer under the therapy with ipatasertib, which provides some theoretical basis for clinical assessment.

Non-Coding RNAs and Resistance to Anticancer Drugs in Gastrointestinal Tumors

Non-coding RNAs are important regulators of gene expression and transcription. It is well established that impaired non-coding RNA expression especially the one of long non-coding RNAs and microRNAs is involved in a number of pathological conditions including cancer. Non-coding RNAs are responsible for the development of resistance to anticancer treatments as they regulate drug resistance-related genes, affect intracellular drug concentrations, induce alternative signaling pathways, alter drug efficiency via blocking cell cycle regulation, and DNA damage response. Furthermore, they can prevent therapeutic-induced cell death and promote epithelial-mesenchymal transition (EMT) and elicit non-cell autonomous mechanisms of resistance. In this review, we summarize the role of non-coding RNAs for different mechanisms resulting in drug resistance (e.g., drug transport, drug metabolism, cell cycle regulation, regulation of apoptotic pathways, cancer stem cells, and EMT) in the context of gastrointestinal cancers.

Beta-elemene increases chemosensitivity to 5-fluorouracil through down-regulating microRNA-191 expression in colorectal carcinoma cells

Colorectal carcinoma is a common malignant tumor occurring in the alimentary system. Despite developments of modern medicine, developed resistance to 5-fluorouracil (5-FU) may lead to poor prognosis. Herein, we aimed to explore the effects of beta-elemene on colorectal carcinoma cells (HCT116 and HT29) as well as the underlying mechanisms. Beta-elemene reduced cell viability and induced apoptosis in HCT116 and HT29 cells. Increased apoptosis following beta-elemene exposure was due to enhanced sensitivity to 5-FU through down-regulating miR-191. Expression of key kinases, including Wnt3a, and β-catenin, were down-regulated by beta-elemene through a miR-191 mechanism. Moreover, beta-elemene might improve resistance of colorectal carcinoma cells to 5-FU by down-regulating miR-191, thereby inhibiting the Wnt/β-catenin pathway.

Distinct apoptotic blocks mediate resistance to panHER inhibitors in HER2+ breast cancer cells

Despite the development of novel targeted therapies, de novo or acquired chemoresistance remains a significant factor for treatment failure in breast cancer therapeutics. Neratinib and dacomitinib are irreversible panHER inhibitors, which block their autophosphorylation and downstream signaling. Moreover, neratinib and dacomitinib have been shown to activate cell death in HER2-overexpressing cell lines. Here we showed that increased MCL1 and decreased BIM and PUMA mediated resistance to neratinib in ZR-75-30 and SKBR3 cells while increased BCL-XL and BCL-2 and decreased BIM and PUMA promoted neratinib resistance in BT474 cells. Cells were also cross-resistant to dacomitinib. BH3 profiles of HER2+ breast cancer cells efficiently predicted antiapoptotic protein dependence and development of resistance to panHER inhibitors. Reactivation of ERK1/2 was primarily responsible for acquired resistance in SKBR3 and ZR-75-30 cells. Adding specific ERK1/2 inhibitor SCH772984 to neratinib or dacomitinib led to increased apoptotic response in neratinib-resistant SKBR3 and ZR-75-30 cells, but we did not detect a similar response in neratinib-resistant BT474 cells. Accordingly, suppression of BCL-2/BCL-XL by ABT-737 was required in addition to ERK1/2 inhibition for neratinib- or dacomitinib-induced apoptosis in neratinib-resistant BT474 cells. Our results showed that different mitochondrial apoptotic blocks mediated acquired panHER inhibitor resistance in HER2+ breast cancer cell lines as well as highlighted the potential of BH3 profiling assay in prediction of panHER inhibitor resistance in breast cancer cells.

miR-503 suppresses the proliferation and metastasis of esophageal squamous cell carcinoma by triggering autophagy via PKA/mTOR signaling

MicroRNA (miR)-503 is involved in the regulation of the malignant phenotype in multiple tumor types, and has been proven to be a novel diagnostic and therapeutic target; however, its function and mechanisms of action have not yet been fully elucidated in esophageal squamous cell carcinoma (ESCC). In the current study, we detected miR‑503 expression by RT‑qPCR and found that miR‑503 expression was increased in ESCC, but negatively correlated with lymph node metastasis, TNM stage and tumor differentiation. Functionally, we confirmed that miR‑503 inhibited the proliferation and metastasis of ESCC cells by triggering cellular autophagy. Mechanistically, we confirmed that miR‑503 exerted its biological effects by targeting protein kinase CAMP‑activated catalytic subunit alpha (PRKACA) in ESCC by dual luciferase reporter assay. Moreover, miR‑503 was found to trigger autophagy in ESCC cells through the protein kinase A (PKA)/mammalian target of rapamycin (mTOR) pathway. Taken together, our results demonstrate that miR‑503 suppresses the proliferation and metastasis of ESCC via the activation of autophagy, mediated by the PKA/mTOR signaling pathway.

Drug-resistance in doxorubicin-resistant FL5.12 hematopoietic cells: elevated MDR1, drug efflux and side-population positive and decreased BCL2-family member expression

Chemotherapeutic drug treatment can result in the emergence of drug-resistant cells. By culturing an interleukin-3 (IL-3)-dependent cell line, FL5.12 cells in the presence of the chemotherapeutic drug doxorubicin, we isolated FL/Doxo cells which are multi-drug resistant. Increased levels of drug efflux were detected in FL/Doxo cells which could be inhibited by the MDR1 inhibitor verapamil but not by the MRP1 inhibitor MK571. The effects of TP53 and MEK1 were examined by infection of FL/Doxo cells with retroviruses encoding either a dominant negative TP-53 gene (FL/Doxo+ TP53 (DN) or a constitutively-activated MEK-1 gene (FL/Doxo + MEK1 (CA). Elevated MDR1 but not MRP1 mRNA transcripts were detected by quantitative RT-PCR in the drug-resistant cells while transcripts encoding anti-apoptotic genes such as: BCL2, BCLXL and MCL1 were observed at higher levels in the drug-sensitive FL5.12 cells. The percentage of cells that were side-population positive was increased in the drug-resistant cells compared to the parental line. Drug-resistance and side-positive population cells have been associated with cancer stem cells (CSC). Our studies suggest mechanisms which could allow the targeting of these molecules to prevent drug-resistance.

Expression and clinical significance of ATM and PUMA gene in patients with colorectal cancer

The expression of ataxia-telangiectasia mutated (ATM) and p53 upregulated modulator of apoptosis (PUMA) genes in patients with colorectal cancer were investigated, to explore the correlation between the expression of ATM and PUMA and tumor development, to evaluate the clinical significance of ATM and PUMA in the treatment of colorectal cancer. Quantitative real-time PCR was used to detect the expression of ATM and PUMA in tumor tissue and adjacent healthy tissue of 67 patients with colorectal cancer and in normal colorectal tissue of 33 patients with colorectal polyps at mRNA level. The expression level of ATM mRNA in colorectal cancer tissues was significantly higher than that in normal mucosa tissues and adjacent non-cancerous tissue (P≤0.05), while no significant differences in expression level of ATM mRNA were found between normal mucosa tissues and adjacent noncancerous tissue (P=0.07). There was a negative correlation between the expression of ATM mRNA and the degree of differentiation of colorectal cancer (r= -0.312, P=0.013), while expression level of ATM mRNA was not significantly correlated with the age, sex, tumor invasion, lymph node metastasis or clinical stage (P>0.05). Expression levels of PUMA mRNA in colorectal cancer tissues, adjacent noncancerous tissue and normal tissues were 0.68±0.07, 0.88±0.04 and 1.76±0.06, respectively. Expression level of PUMA mRNA in colorectal cancer tissues and adjacent noncancerous tissue was significantly lower than that in normal colorectal tissues (P<0.05). The results showed that ATM mRNA is expressed abnormally in colorectal cancer tissues. Expression of PUMA gene in colorectal carcinoma is downregulated, and is negatively correlated with the occurrence of cancer.

Targeting signaling and apoptotic pathways involved in chemotherapeutic drug-resistance of hematopoietic cells

A critical problem in leukemia as well as other cancer therapies is the development of chemotherapeutic drug-resistance. We have developed models of hematopoietic drug resistance that are based on expression of dominant-negative TP53 [TP53 (DN)] or constitutively-active MEK1 [MEK1(CA)] oncogenes in the presence of chemotherapeutic drugs. In human cancer, functional TP53 activity is often lost in human cancers. Also, activation of the Raf/MEK/ERK pathway frequently occurs due to mutations/amplification of upstream components of this and other interacting pathways. FL5.12 is an interleukin-3 (IL−3) dependent hematopoietic cell line that is sensitive to doxorubicin (a.k.a Adriamycin). FL/Doxo is a derivative cell line that was isolated by culturing the parental FL5.12 cells in doxorubicin for prolonged periods of time. FL/Doxo + TP53 (DN) and FL/Doxo + MEK1 (CA) are FL/Doxo derivate cell lines that were infected with retrovirus encoding TP53 (DN) or MEK1 (CA) and are more resistant to doxorubicin than FL/Doxo cells. This panel of cell lines displayed differences in the sensitivity to inhibitors that suppress mTORC1, BCL2/BCLXL, MEK1 or MDM2 activities, as well as, the proteasomal inhibitor MG132. The expression of key genes involved in cell growth and drug-resistance (e.g., MDM2, MDR1, BAX) also varied in these cells. Thus, we can begin to understand some of the key genes that are involved in the resistance of hematopoietic cells to chemotherapeutic drugs and targeted therapeutics.

Dynamics of cytotoxic T cell subsets during immunotherapy predicts outcome in acute myeloid leukemia

Preventing relapse after chemotherapy remains a challenge in acute myeloid leukemia (AML). Eighty-four non-transplanted AML patients in first complete remission received relapse-preventive immunotherapy with histamine dihydrochloride and low-dose interleukin-2 in an international phase IV trial (ClinicalTrials.gov; NCT01347996). Blood samples were drawn during cycles of immunotherapy and analyzed for CD8+ (cytotoxic) T cell phenotypes in blood. During the first cycle of therapy, a re-distribution of cytotoxic T cells was observed comprising a reduction of T effector memory cells and a concomitant increase of T effector cells. The dynamics of T cell subtypes during immunotherapy prognosticated relapse and survival, in particular among older patients and remained significantly predictive of clinical outcome after correction for potential confounders. Presence of CD8+ T cells with specificity for leukemia-associated antigens identified patients with low relapse risk. Our results point to novel aspects of T cell-mediated immunosurveillance in AML and provide conceivable biomarkers in relapse-preventive immunotherapy.