MicroRNA‐93‐5p expression in tumor tissue and its tumor suppressor function via targeting programmed death ligand‐1 in colorectal cancer

The 3' Non-Coding Sequence Negatively Regulates PD-L1 Expression, and Its Regulators Are Systematically Identified in Pan-Cancer

The 3'-untranslated region (3'-UTR) of PD-L1 is significantly longer than the coding sequences (CDSs). However, its role and regulators have been little studied. We deleted whole 3'-UTR region by CRISPR-Cas9. Prognostic analysis was performed using online tools. Immune infiltration analysis was performed using the Timer and Xcell packages. Immunotherapy response prediction and Cox regression was performed using the R software. MicroRNA network analysis was conducted by the Cytoscape software. The level of PD-L1 was significantly and dramatically up-regulated in cells after deleting the 3'-UTR. Additionally, we discovered a panel of 43 RNA-binding proteins (RBPs) whose expression correlates with PD-L1 in the majority of cancer cell lines and tumor tissues. Among these RBPs, PARP14 is widely associated with immune checkpoints, the tumor microenvironment, and immune-infiltrating cells in various cancer types. We also identified 38 microRNAs whose individual expressions are associated with PD-L1 across different cancers. Notably, miR-3139, miR-4761, and miR-15a-5p showed significant associations with PD-L1 in most cancer types. Furthermore, we revealed 21 m6A regulators that strongly correlate with PD-L1. Importantly, by combining the identified RBP and m6A regulators, we established an immune signature consisting of RBMS1, QKI, ZC3HAV1, and RBM38. This signature can be used to predict the responsiveness of cancer patients to immune checkpoint blockade treatment. We demonstrated the critical role of the 3'-UTR in the regulation of PD-L1 and identified a significant number of potential PD-L1 regulators across various types of cancer. The biomarker signature generated from our findings shows promise in predicting patient prognosis. However, further biological investigation is necessary to explore the potential of these PD-L1 regulators.

MiRNA-93: a novel signature in human disorders and drug resistance

miRNA-93 is a member of the miR-106b-25 family and is encoded by a gene on chromosome 7q22.1. They play a role in the etiology of various diseases, including cancer, Parkinson's disease, hepatic injury, osteoarthritis, acute myocardial infarction, atherosclerosis, rheumatoid arthritis, and chronic kidney disease. Different studies have found that this miRNA has opposing roles in the context of cancer. Recently, miRNA-93 has been downregulated in breast cancer, gastric cancer, colorectal cancer, pancreatic cancer, bladder cancer, cervical cancer, and renal cancer. However, miRNA-93 is up-regulated in a wide variety of malignancies, such as lung, colorectal, glioma, prostate, osteosarcoma, and hepatocellular carcinoma. The aim of the current review is to provide an overview of miRNA-93's function in cancer disorder progression and non-cancer disorders, with a focus on dysregulated signaling pathways. We also give an overview of this miRNA's function as a biomarker of prognosis in cancer and emphasize how it contributes to drug resistance based on in vivo, in vitro, and human studies. Video Abstract.

Multifunctional Mesoporous Silica-Coated Gold Nanorods Mediate Mild Photothermal Heating-Enhanced Gene/Immunotherapy for Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer worldwide and the second leading cause of cancer-related deaths in the world. It is urgent to search for safe and effective therapies to address the CRC crisis. The siRNA-based RNA interference targeted silencing of PD-L1 has extensive potential in CRC treatment but is limited by the lack of efficient delivery vectors. In this work, the novel cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODNs)/siPD-L1 co-delivery vectors AuNRs@MS/CpG ODN@PEG-bPEI (ASCP) were successfully prepared by two-step surface modification of CpG ODNs-loading and polyethylene glycol-branched polyethyleneimine-coating around mesoporous silica-coated gold nanorods. ASCP promoted dendritic cells (DCs) maturation by delivering CpG ODNs, exhibiting excellent biosafety. Next, mild photothermal therapy (MPTT) mediated by ASCP killed tumor cells and released tumor-associated antigens, further promoting DC maturation. Furthermore, ASCP exhibited mild photothermal heating-enhanced performance as gene vectors, resulting in an increased PD-L1 gene silencing effect. Enhanced DCs maturity and enhanced PD-L1 gene silencing significantly promoted the anti-tumor immune response. Finally, the combination of MPTT and mild photothermal heating-enhanced gene/immunotherapy effectively killed MC38 cells, leading to strong inhibition of CRC. Overall, this work provided new insights into the design of mild photothermal/gene/immune synergies for tumor therapy and may contribute to translational nanomedicine for CRC treatment.

MicroRNAs with Multiple Targets of Immune Checkpoints, as a Potential Sensitizer for Immune Checkpoint Inhibitors in Breast Cancer Treatment

Breast cancer is the most common cancer type and the leading cause of cancer-associated mortality in women worldwide. In recent years, immune checkpoint inhibitors (ICIs) have made significant progress in the treatment of breast cancer, yet there are still a considerable number of patients who are unable to gain lasting and ideal clinical benefits by immunotherapy alone, which leads to the development of a combination regimen as a novel research hotspot. Furthermore, one miRNA can target several checkpoint molecules, mimicking the therapeutic effect of a combined immune checkpoint blockade (ICB), which means that the miRNA therapy has been considered to increase the efficiency of ICIs. In this review, we summarized potential miRNA therapeutics candidates which can affect multiple targets of immune checkpoints in breast cancer with more therapeutic potential, and the obstacles to applying miRNA therapeutically through the analyses of the resources available from a drug target perspective. We also included the content of "too many targets for miRNA effect" (TMTME), combined with applying TargetScan database, to discuss adverse events. This review aims to ignite enthusiasm to explore the application of miRNAs with multiple targets of immune checkpoint molecules, in combination with ICIs for treating breast cancer.

Loss of SATB2 expression correlates with cytokeratin 7 and PD-L1 tumor cell positivity and aggressiveness in colorectal cancer

Colorectal carcinoma (CRC) is a disease that causes significant morbidity and mortality worldwide. To improve treatment, new biomarkers are needed to allow better patient risk stratification in terms of prognosis. This study aimed to clarify the prognostic significance of colonic-specific transcription factor special AT-rich sequence-binding protein 2 (SATB2), cytoskeletal protein cytokeratin 7 (CK7), and immune checkpoint molecule programmed death-ligand 1 (PD-L1). We analyzed a cohort of 285 patients with surgically treated CRC for quantitative associations among the three markers and five traditional prognostic indicators (i.e., tumor stage, histological grade, variant morphology, laterality, and mismatch-repair/MMR status). The results showed that loss of SATB2 expression had significant negative prognostic implications relative to overall survival (OS) and cancer-specific survival (CSS), significantly shortened 5 years OS and CSS and 10 years CSS in patients with CRC expressing CK7, and borderline insignificantly shortened OS in patients with PD-L1 + CRC. PD-L1 showed a significant negative impact in cases with strong expression (membranous staining in 50-100% of tumor cells). Loss of SATB2 was associated with CK7 expression, advanced tumor stage, mucinous or signet ring cell morphology, high grade, right-sided localization but was borderline insignificant relative to PD-L1 expression. CK7 expression was associated with high grade and SATB2 loss. Additionally, a separate analysis of 248 neoadjuvant therapy-naïve cases was performed with mostly similar results. The loss of SATB2 and CK7 expression were significant negative predictors in the multivariate analysis adjusted for associated parameters and patient age. In summary, loss of SATB2 expression and gain of CK7 and strong PD-L1 expression characterize an aggressive phenotype of CRC.

Interplay between programmed death-ligand 1 and non-coding RNAs

Programmed death-ligand 1 (PD-L1) is a transmembrane protein with essential roles in the suppression of adaptive immune responses. As an immune checkpoint molecule, PD-L1 can be exploited by cancer cells to evade the anti-tumor attacks initiated by the immune system. Thus, blockade of the PD1/PD-L1 axis can eliminate the suppressive signals and release the antitumor immune responses. Identification of the underlying mechanisms of modulation of the activity of the PD1/PD-L1 axis would facilitate the design of more efficacious therapeutic options and better assignment of patients for each option. Recent studies have confirmed the interactions between miRNAs/lncRNAs/circ-RNAs and the PD1/PD-L1 axis. In the current review, we give a summary of interactions between these transcripts and PD-L1 in the context of cancer. We also overview the consequences of these interactions in the determination of the response of patients to anti-cancer drugs.

m6A Modification of Long Non-Coding RNA HNF1A-AS1 Facilitates Cell Cycle Progression in Colorectal Cancer via IGF2BP2-Mediated CCND1 mRNA Stabilization

Background: Long non-coding RNAs modulate tumor occurrence through different molecular mechanisms. It had been reported that HNF1A-AS1 (HNF1A Antisense RNA 1) was differently expressed in multiple tumors. The role of HNF1A-AS1 in colorectal cancer was less analyzed, and the mechanism of regulating the cell cycle has not been completely elucidated. Methods: Differentially expressed lncRNAs were screened out from the TCGA database. HNF1A-AS1 was examined in CRC clinical samples and cell lines by RT-qPCR. CCK8 assay, colony formation assay, flow cytometry, transwell assays, tube forming assay and vivo experiments were performed to study the function of HNF1A-AS1 in CRC tumor progression. Bioinformatic analysis, luciferase report assay, RNA pull-down and RIP assays were carried out to explore proteins binding HNF1A-AS1 and the potential downstream targets. Results: Our results showed that HNF1A-AS1 was upregulated in CRC and associated with unfavorable prognosis. HNF1A-AS1 promoted proliferation, migration and angiogenesis, accelerated cell cycle and reduced cell apoptosis in CRC. Bioinformatics prediction and further experiments proved that HNF1A-AS1 could promote CCND1 expression by suppressing PDCD4 or competitively sponging miR-93-5p. Meanwhile, METTL3 mediated HNF1A-AS1 m⁶A modification and affected its RNA stability. HNF1A-AS1/IGF2BP2/CCND1 may act as a complex to regulate the stability of CCND1. Conclusion: In summary, our result reveals the novel mechanism in which m⁶A-mediated HNF1A-AS1/IGF2BP2/CCND1 axis promotes CRC cell cycle progression, along with competitively sponging miR-93-5p to upregulate CCND1, demonstrating its significant role in cell cycle regulation and suggesting that HNF1A-AS1 may act as a potential prognostic marker of colorectal cancer in the future.

The Role and Interactions of Programmed Cell Death 4 and its Regulation by microRNA in Transformed Cells of the Gastrointestinal Tract

Data from GLOBOCAN 2020 estimates that there were 19.3 million new cases of cancer and 10.0 million cancer-related deaths in 2020 and that this is predicted to increase by 47% in 2040. The combined burden of cancers of the gastrointestinal (GI) tract, including oesophageal-, gastric- and colorectal cancers, resulted in 22.6% of the cancer-related deaths in 2020 and 18.7% of new diagnosed cases. Understanding the aetiology of GI tract cancers should have a major impact on future therapies and lessen this substantial burden of disease. Many cancers of the GI tract have suppression of the tumour suppressor Programmed Cell Death 4 (PDCD4) and this has been linked to the expression of microRNAs which bind to the untranslated region of PDCD4 mRNA and either inhibit translation or target the mRNA for degradation. This review highlights the properties of PDCD4 and documents the evidence for the regulation of PDCD4 expression by microRNAs in cancers of the GI tract.

Functions of non-coding RNAs in regulating cancer drug targets

With the development of precision medicine, the efficiency of tumor treatment has been significantly improved. More attention has been paid to targeted therapy and immunotherapy as the key to precision treatment of cancer. Targeting epidermal growth factor receptor (EGFR) has become one of the most important targeted treatments for various cancers. Comparing with traditional chemotherapy drugs, targeting EGFR is highly selective in killing tumor cells with better safety, tolerability and less side effect. In addition, tumor immunotherapy has become the fourth largest tumor therapy after surgery, radiotherapy and chemotherapy, especially immune checkpoint inhibitors. However, these treatments still produce a certain degree of drug resistance. Non-coding RNAs (ncRNAs) were found to play a key role in carcinogenesis, treatment and regulation of the efficacy of anticancer drugs in the past few years. Therefore, in this review, we aim to summarize the targeted treatment of cancers and the functions of ncRNAs in cancer treatment.

MiR-93-5p regulates tumorigenesis and tumor immunity by targeting PD-L1/CCND1 in breast cancer

Background

Challenges in medical care posed by rapid tumor progression, individualized responses to therapy, and the heterogeneous characteristics of breast cancer (BRCA) highlight the urgent need for new treatment strategies, as well as therapeutic and prognostic markers. Accumulating evidence has revealed that microRNAs broadly participate in carcinogenesis, but our understanding of the role of miR-93-5p in BRCA remains limited.

Methods

The prognosis of miR-93-5p, programmed cell death-ligand 1 (PD-L1) and CCND1 were analyzed by datasets. Freshly excised breast cancer tissues (N=33) and adjacent noncancerous tissues (N=18) were collected to detect the expression of CCND1 and PD-L1 by immunohistochemistry (IHC). Quantitative real-time PCR (qRT-PCR) and Western blot were used to test the expression of miR-93-5p, PD-L1 and CCND1 after transfected mimics or inhibitors. Dual-luciferase reporter assay indicates the direct targeting between miR-93-5p and PD-L1.

Results

Bioinformatics analysis demonstrated that miR-93-5p plays differential roles in various tumors, and further verification using qRT-PCR revealed that the expression levels of miR-93-5p were lower in MDA-MB-231 cells than in noncancerous breast cells. In addition, we confirmed that PD-L1 and CCND1 generated mutual effects, and miR-93-5p directly targets the PD-L1/CCND1 signaling pathway to influence their accumulation and distribution in the cell membrane, nucleus, and cytoplasm, mediating tumor progression and immune regulation in BRCA.

Conclusions

Taken together, miR-93-5p could regulate tumorigenesis and tumor immunity by targeting PD-L1/CCND1 in BRCA and our research provides a rationale for therapy with miR-93-5p to overcome immune escape and improve risk stratification.

A scoping review on the potentiality of PD-L1-inhibiting microRNAs in treating colorectal cancer: Toward single-cell sequencing-guided biocompatible-based delivery

Tumoral programmed cell death ligand 1 (PD-L1) has been implicated in the immune evasion and development of colorectal cancer. Although monoclonal immune checkpoint inhibitors can exclusively improve the prognosis of patients with microsatellite instability-high (MSI-H) and tumor mutational burden-high (TMB-H) colorectal cancer, specific tumor-suppressive microRNAs (miRs) can regulate multiple oncogenic pathways and inhibit the de novo expression of oncoproteins, like PD-L1, both in microsatellite stable (MSS) and MSI-H colorectal cancer cells. This scoping review aimed to discuss the currently available evidence regarding the therapeutic potentiality of PD-L1-inhibiting miRs for colorectal cancer. For this purpose, the Web of Science, Scopus, and PubMed databases were systematically searched to obtain peer-reviewed studies published before 17 March 2021. We have found that miR-191-5p, miR-382-3p, miR-148a-3p, miR-93-5p, miR-200a-3p, miR-200c-3p, miR-138-5p, miR-140-3p, and miR-15b-5p can inhibit tumoral PD-L1 in colorectal cancer cells. Besides inhibiting PD-L1, miR-140-3p, miR-382-3p, miR-148a-3p, miR-93-5p, miR-200a-3p, miR-200c-3p, miR-138-5p, and miR-15b-5p can substantially reduce tumor migration, inhibit tumor development, stimulate anti-tumoral immune responses, decrease tumor viability, and enhance the chemosensitivity of colorectal cancer cells regardless of the microsatellite state. Concerning the specific, effective, and safe delivery of these miRs, the single-cell sequencing-guided biocompatible-based delivery of these miRs can increase the specificity of miR delivery, decrease the toxicity of traditional nanoparticles, transform the immunosuppressive tumor microenvironment into the proinflammatory one, suppress tumor development, decrease tumor migration, and enhance the chemosensitivity of tumoral cells regardless of the microsatellite state.

High density of cytotoxic T-lymphocytes is linked to tumoral PD-L1 expression regardless of the mismatch repair status in colorectal cancer

BACKGROUND

Immune checkpoint-inhibitors targeting the PD-1/PD-L1 system are FDA approved in microsatellite instable (MSI) or mismatch repair deficient (dMMR) colorectal cancer (CRC). PD-L1 expression is tightly linked to features connected to immune checkpoint inhibitor response, but studies on large subsets of cancers analyzing the correlation between different status of MSI/dMMR, tumor infiltrating lymphocytes and PD-L1 expression are still lacking.

METHODS

More than 1800 CRC were analyzed for PD-L1 by immunohistochemistry in a tissue microarray format. Data were compared to MMR, the number of intratumoral CD8⁺ cytotoxic T-cells, and adverse clinico-pathological parameters. Different cutoff levels for defining PD-L1 positivity in tumor cells (1%, 5%, 10%, and 50%) yielded comparable results.

RESULTS

At a cutoff level of 5%, PD-L1 positivity was seen in 5.1% of tumors. PD-L1 was more often positive in dMMR (18.6%) than in MMR proficient (pMMR) cancers (4.1%; p < 0.0001). The number of intratumoral CD8⁺ lymphocytes was strikingly higher in PD-L1 positive (939.5 ± 118.2) than in PD-L1 negative cancers (310.5 ± 24.8). A higher number of intratumoral CD8⁺ lymphocytes was found in dMMR CRC (PD-L1 positive: 1999.7 ± 322.0; PD-L1 negative: 398.6 ± 128.0; p < 0.0001) compared to pMMR CRC (PD-L1 positive: 793.2 ± 124.8; PD-L1 negative: 297.2 ± 24.2; p < 0.0001). In dMMR and pMMR CRC, PD-L1 expression in tumor cells was unrelated to tumor stage, lymph node status or lymphatic/venous invasion. PD-L1 positivity in tumor associated immune cells was seen in 47.5% of cases and was significantly linked to high numbers of tumor infiltrating CD8⁺, low tumor stage, and absence of lymph node metastasis and lymphatic/venous invasion (p < 0.0001 each).

CONCLUSION

The data support the previously suggested fact that PD-L1 expression in tumor cells is driven by extensive cytotoxic T-cell infiltration in highly immunogenic dMMR and pMMR CRC. Frequent and intense PD-L1 expression in tumor cells of dMMR CRC may contribute to the high response rates of dMMR CRC to immune checkpoint-inhibitors.

miRNA Clusters with Up-Regulated Expression in Colorectal Cancer

Simple Summary

As miRNAs show the capacity to be used as CRC biomarkers, we analysed experimentally validated data about frequently up-regulated miRNA clusters in CRC tissue. We identified 15 clusters that showed increased expression in CRC: miR-106a/363, miR-106b/93/25, miR-17/92a-1, miR-181a-1/181b-1, miR-181a-2/181b-2, miR-181c/181d, miR-183/96/182, miR-191/425, miR-200c/141, miR-203a/203b, miR-222/221, mir-23a/27a/24-2, mir-29b-1/29a, mir-301b/130b and mir-452/224. Cluster positions in the genome are intronic or intergenic. Most clusters are regulated by several transcription factors, and by long non-coding RNAs. In some cases, co-expression of miRNA with other cluster members or host gene has been proven. miRNA expression patterns in cancer tissue, blood and faeces were compared. The members of the selected clusters target 181 genes. Their functions and corresponding pathways were revealed with the use of Panther analysis. Clusters miR-17/92a-1, miR-106a/363, miR-106b/93/25 and miR-183/96/182 showed the strongest association with metastasis occurrence and poor patient survival, implicating them as the most promising targets of translational research.

Abstract

Colorectal cancer (CRC) is one of the most common malignancies in Europe and North America. Early diagnosis is a key feature of efficient CRC treatment. As miRNAs can be used as CRC biomarkers, the aim of the present study was to analyse experimentally validated data on frequently up-regulated miRNA clusters in CRC tissue and investigate their members with respect to clinicopathological characteristics of patients. Based on available data, 15 up-regulated clusters, miR-106a/363, miR-106b/93/25, miR-17/92a-1, miR-181a-1/181b-1, miR-181a-2/181b-2, miR-181c/181d, miR-183/96/182, miR-191/425, miR-200c/141, miR-203a/203b, miR-222/221, mir-23a/27a/24-2, mir-29b-1/29a, mir-301b/130b and mir-452/224, were selected. The positions of such clusters in the genome can be intronic or intergenic. Most clusters are regulated by several transcription factors, and miRNAs are also sponged by specific long non-coding RNAs. In some cases, co-expression of miRNA with other cluster members or host gene has been proven. miRNA expression patterns in cancer tissue, blood and faeces were compared. Based on experimental evidence, 181 target genes of selected clusters were identified. Panther analysis was used to reveal the functions of the target genes and their corresponding pathways. Clusters miR-17/92a-1, miR-106a/363, miR-106b/93/25 and miR-183/96/182 showed the strongest association with metastasis occurrence and poor patient survival, implicating them as the most promising targets of translational research.

MicroRNAs as important contributors in the pathogenesis of colorectal cancer

Colorectal cancer (CRC) is the third most fatal and fourth most frequently diagnosed neoplasm in the world. Numerous non-coding RNAs have been shown to contribute in the development of CRC. MicroRNAs (miRNAs) are among the mostly assessed non-coding RNAs in CRC. These transcripts influence expression and activity of TGF-β, Wnt/β-catenin, MAPK, PI3K/AKT and other CRC-related pathways. In the context of CRC, miRNAs interact with long non-coding RNAs to influence CRC course. Stool and serum levels of miRNAs have been used to distinguish CRC patients from healthy controls, indicating diagnostic roles of these transcripts in CRC. Therapeutic application of miRNAs in CRC has been assessed in animal models, yet has not been verified in clinical settings. In the current review, we have provided a recent update on the role of miRNAs in CRC development as well as diagnostic and prognostic approaches.

HOXD Antisense Growth-Associated Long Noncoding RNA Promotes Triple-Negative Breast Cancer Progression by Activating Wnt Signaling Pathway

PURPOSE

Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer owing to high heterogeneity, aggressive nature, and lack of treatment options, which has a substantial deleterious effect on patients' lives. HOXD antisense growth-associated long noncoding RNA (lncRNA) (HAGLR) plays tumor-promoting roles in many cancers. In this study, we aimed to explore the role of HAGLR in TNBC.

METHODS

Quantitative real-time polymerase chain reaction assays were used to examine the expression of RNAs. Functional experiments were conducted to test the biological behavior of TNBC cells. Moreover, MS2-RNA immunoprecipitation, luciferase reporter, and RNA pull-down assays were conducted to verify the binding relationship between HAGLR, microRNA-143-5p (miR-143-5p), and serine- and arginine-rich splicing factor 1 (SRSF1).

RESULTS

HAGLR was found to be highly expressed in TNBC tissues and cells, and inhibiting HAGLR suppressed cell proliferation, migration, and invasion and promoted cell apoptosis in TNBC. Meanwhile, miR-93-5p was shown to bind to HAGLR and SRSF1. In addition, SRSF1 plays an oncogenic role in TNBC. Importantly, HAGLR could activate the Wnt signaling pathway by sponging miR-93-5p to upregulate SRSF1; thus, accelerating TNBC progression.

CONCLUSION

HAGLR could promote the progression of TNBC through the miR-93-5p/SRSF1 axis to activate the Wnt signaling pathway.

Downregulating Long Non-coding RNAs CTBP1-AS2 Inhibits Colorectal Cancer Development by Modulating the miR-93-5p/TGF-β/SMAD2/3 Pathway

Background: Colorectal cancer (CRC), the most commonly diagnosed cancer in the world, has a high mortality rate. In recent decades, long non-coding RNAs (lncRNAs) have been proven to exert an important effect on CRC growth. However, the CTBP1-AS2 expression and function in CRC are largely unknown.

Materials and Methods: The CTBP1-AS2 and miR-93-5p expression in CRC and para-cancerous tissues was detected by reverse transcription-PCR. The expression of CTBP1-AS2, miR-93-5p and the transforming growth factor-beta (TGF-β)/small mothers against decapentaplegic 2/3 (SMAD2/3) pathway was selectively regulated to study the correlation between CTBP1-AS2 expression and prognosis of patients with CRC. CRC cell proliferation, apoptosis, and invasion were measured in vivo and in vitro. In addition, bioinformatics was applied to explore the targeting relationship between CTBP1-AS2 and miR-93-5p. The targeting binding sites between CTBP1-AS2 and miR-93-5p, as well as between miR-93-5p and TGF-β, were verified by the dual-luciferase reporter assay and the RNA immunoprecipitation experiment.

Results: Compared with normal para-cancerous tissues, CTBP1-AS2 was considerably overexpressed in CRC tissues and was closely associated with worse survival of patients with CRC. Functionally, gain and loss in experiments illustrated that CTBP1-AS2 accelerated CRC cell proliferation and invasion and inhibited cell apoptosis. Mechanistically, CTBP1-AS2 regulated the malignant phenotype of tumor cells through the TGF-β/SMAD2/3 pathway. Moreover, miR-93-5p, as an endogenous competitive RNA of CTBP1-AS2, attenuated the oncogenic effects mediated by CTBP1-AS2.

Conclusion: CTBP1-AS2 promotes the TGF-β/SMAD2/3 pathway activation by inhibiting miR-93-5p, thereby accelerating CRC development.

miR-93 regulates liver tumor initiating cells expansion and predicts chemotherapeutic response of patients

Tumor initiating cells (T-ICs) play an important role in tumorigenesis, progression, metastasis, recurrence and drug resistance, but the underlying mechanism was not clearly elucidated. In our study, we found that miR-93 was highly expressed in liver T-ICs. Self-renewal and tumorigenesis ability of liver T-ICs were enhanced by miR-93 overexpression and attenuated by miR-93 interference. Mechanically, miR-93 regulated liver T-ICs by binding to 3'-UTR of myotubularin-related protein 3 (MTMR3). In addition, miR-93 was found highly expressed in cisplatin or sorafenib-resistant liver cancer tissues. Interference of miR-93 sensitizes hepatoma cells to cisplatin or sorafenib treatment. Clinical cohort analysis showed that Hepatocellular carcinoma (HCC) patients with low miR-93 were benefit more from TACE or sorafenib treatment. In conclusion, our study demonstrates a new regulation mechanism of liver T-ICs, a new target for HCC, and a biomarker for postoperative TACE or sorafenib.

MiR-93/HMGB3 regulatory axis exerts tumor suppressive effects in colorectal carcinoma cells

OBJECTIVE

MicroRNA (miR)-93 has been proven to mediate the initiation and progression of colorectal carcinoma (CRC); however, the mechanisms by which miR-93 mediates CRC development need deeper elucidation. The present study is designed to investigate the association between miR-93 and high mobility group box 3 (HMGB3), as well as the functions of miR-93, in CRC.

METHODS

miR-93 expression was quantified by RT-qPCR. CRC cells were transfected or cotransfected with miR-93 mimic, miR-93 inhibitor, pcDNA3.1-HMGB3 and sh-HMGB3, and then the proliferative, migratory and invasive capacities were detected in addition to the apoptotic rate. Western blotting assessed the expression levels of HMGB3, PI3K, p-PI3K, AKT and p-AKT. The interaction between miR-93 and HMGB3 was identified.

RESULTS

In CRC tissues, miR-93 was downregulated and HMGB3 was upregulated. LOVO and SW480 cells transfected with miR-93 mimic exhibited reduced proliferation, invasion and migration as well as increased apoptosis. The ratios of p-PI3K/PI3K and p-AKT/AKT were declined after miR-93 mimic was introduced into the CRC cell lines. miR-93 negatively downregulated HMGB3, and introduction of pcDNA3,1-HMGB3 could counteract, in part, the inhibitory effects of miR-93 on the malignant properties of CRC cells as well as the ratios of p-PI3K/PI3K and p-AKT/AKT.

CONCLUSION

miR-93 targeted HMGB3 to block the activation of the PI3K/AKT pathway and thus enhance CRC cell apoptosis.

MicroRNA-15a Carried by Mesenchymal Stem Cell-Derived Extracellular Vesicles Inhibits the Immune Evasion of Colorectal Cancer Cells by Regulating the KDM4B/HOXC4/PD-L1 Axis

The relevance of microRNA-15a (miR-15a) to autoimmunity has been reported. Herein, we intended to probe the potential roles of miR-15a shuttled by adipose-derived mesenchymal stem cells (adMSCs)-derived extracellular vesicles (Evs) in colorectal cancer (CRC). Initially, CRC cells were treated with interferon gamma (IFN-γ) to screen out differentially expressed genes by transcriptome sequencing. Following a 24-h co-culture with 20 μM adMSCs-derived Evs, CRC cell viability, migration, invasion, and apoptosis were assessed. After the determination of histone lysine demethylase 4B (KDM4B) as our target, its regulatory miRNA was predicted by the bioinformatics websites and verified by dual-luciferase and RNA pull-down assays. Intriguingly, KDM4B downregulated homeobox C4 (HOXC4) expression, while HOXC4 bound to the promoter sequence of programmed death-ligand 1 (PD-L1). Thus, we conducted rescue experiments to study the role of KDM4B and HOXC4. Finally, we evaluated the effects of adMSCs on CRC cell growth and immune evasion through in vivo tumorigenesis experiments. AdMSCs-derived Evs overexpressing miR-15a repressed proliferation, migration, and invasion, while it promoted the apoptosis of CRC cells via downregulation of KDM4B. These in vivo findings were reproduced in vitro on CRC immune evasion. Collectively, adMSCs-derived Evs overexpressing miR-15a restricted the immune evasion of CRC via the KDM4B/HOXC4/PD-L1 axis.

HDAC1 regulates the chemosensitivity of laryngeal carcinoma cells via modulation of interleukin-8 expression

Chemotherapies such as 5-fluorouracil (5-FU) and cisplatin (CDDP) have been widely used to treat laryngeal squamous cell carcinoma (LSCC), the second most common head and neck squamous cell carcinoma. However, chemoresistance seriously impairs chemotherapeutic efficacy. Our present study reveals that 5-FU and CDDP treatment increase the expression of histone deacetylase 1 (HDAC1) in LSCC cells. Consistently, increased levels of HDAC1 are observed in chemoresistant cells. Knockdown of HDAC1 significantly restores the sensitivity of LSCC cells, as HDAC1 increases the expression of interleukin-8 (IL-8), which is essential for LSCC chemoresistance. Mechanistically, HDAC1 directly initiates the transcription of IL-8 though binding to its promoter. Simultaneously, si-HDAC1 increases the levels of miR-93, which binds to the 3'UTR of IL-8 mRNA to trigger its degradation. In summary, the HDAC1/IL-8 axis can confer chemotherapeutic resistance to LSCC cells.

NSE, positively regulated by LINC00657-miR-93-5p axis, promotes small cell lung cancer (SCLC) invasion and epithelial-mesenchymal transition (EMT) process

Background: Neuron specific enolase (NSE) is a specific biomarker for SCLC. However, the biological roles and aberrant expression of NSE in SCLC have not been well illustrated. Methods: The expression of NSE, miR-93-5p and LINC00657 in SCLC tissues and cell lines were detected using real time quantitative PCR (qRT-PCR) or immunohistochemistry. CCK8 assay was performed to detect cell proliferation. Cell migration and invasion capabilities were investigated by transwell assay. Epithelial-mesenchymal transition (EMT) process was verified by detecting epithelial marker E-cadherin and mesenchymal marker N-cadherin. The direct interactions between miR-93-5p and NSE or LINC00657 were predicted by bioinformatics tools and verified using dual luciferase reporter assay. Results: Upregulated expression of NSE in SCLC tumor tissues were positively associated with advanced tumor stage, distant metastasis and poor overall survival. Overexpression of NSE promoted cell proliferation, migration, invasion and EMT in SCLC cells, while silence of NSE inhibited these effects. Mechanically, NSE expression was positively correlated with LINC00657, and negatively correlated with miR-93-5p. Moreover, NSE was positively regulated by LINC00657 through sponging of miR-93-5p. LINC00657 and miR-93-5p promoted SCLC cell migration, invasion and EMT by NSE-mediated manner. Conclusion: Overall, our study revealed a novel role of NSE in SCLC. NSE was positively regulated by LINC00657 through competitively interacting with miR-93-5p, which may be potential targets for SCLC patients.

MicroRNA -383-5p restrains the proliferation and migration of breast cancer cells and promotes apoptosis via inhibition of PD-L1

AIMS

MicroRNAs (miRs) play pivotal roles in breast cancer development. The dysregulation of miRs has been associated with PD-L1-mediated immune suppression. This study aimed to examine the effect of transfected miR-383-5p on breast cancer cells and T-cells and its association with clinicopathological features in affected patients.

MAIN METHODS

Initially, miR-383-5p and PD-L1 expression levels were investigated in breast cancer tissues. Then, MDA-MB-231 cells were transfected with miR-383-5p mimics to perform analyses. Cell viability was investigated using the MTT assay, and the annexin V/PI staining assay was performed to examine apoptosis induction. Furthermore, the effect of miR-383-5p on cell migration and cell cycle progression was analyzed using the wound-healing assay and flow cytometry, respectively. Gene and protein expressions were studied using qRT-PCR and western blotting. Finally, the effect of miR-383-5p on T-cells, which were co-cultured with cancer cells, was investigated.

KEY FINDINGS

Compared to non-malignant tissues, PD-L1 was up-regulated, and miR-383-5p expression was downregulated in breast cancer tissues. Moreover, miR-383-5p reduced breast cancer cell viability via inducing apoptosis and modulating the expression of apoptosis-related genes. Besides, miR-383-5p could inhibit the migration of breast cancer cells via down-regulating metastasis-related genes. Besides, transfected miR-383-5p induced the secretion of pro-inflammatory cytokines from T-cells. Furthermore, the results showed that miR-383-5p might exert its tumor-suppressive effect via inhibiting the PI3K/AKT/mTOR pathway. The inhibitory effect of transfected miR-383-5p on the PI3K/AKT/mTOR pathway might be the underlying mechanism for inhibiting tumoral PD-L1 expression.

SIGNIFICANCE

Overall, miR-383-5p can be a promising therapeutic agent for treating breast cancer.

A meta-analysis of CD274 (PD-L1) assessment and prognosis in colorectal cancer and its role in predicting response to anti-PD-1 therapy

BACKGROUND

PD-1 checkpoint inhibitors are novel therapeutic agents in colorectal cancer (CRC). Immunohistochemical staining for CD274 assessment is standardised in upper GI cancer, but not in CRC.

METHODS

Methodologies of relevant studies were scrutinized and meta-analysis of survival and CD274/PDCD1 performed. Furthermore, anti-PD-1 therapy clinical trial results in CRC were assessed with particular emphasis on CD274 assessment.

RESULTS

24 studies were included. CD274 on immune cells was associated with good prognosis. CD274 on tumour cells has heterogenous outcomes and does not meet requirements of a prognostic marker. As a marker of response to anti-PD-1 therapy, CD274 assessment is not standardised in CRC.

CONCLUSION

CD274 does not appear useful as a prognostic marker. As a marker of response to anti-PD-1 therapy, assessment methodology requires standardisation. As the Combined Positive Score (CPS) is used in upper GI cancer, this seems a logical method to adopt. Thresholds for CRC remain to be determined.

MicroRNAs: Multifaceted Regulators of Colorectal Cancer Metastasis and Clinical Applications

Colorectal cancer (CRC) is the third-commonest malignant cancer, and its metastasis is the major reason for cancer-related death. The process of metastasis is highly coordinated and involves a complex cascade of multiple steps. In recent years, miRNAs, as highly conserved, endogenous, noncoding, single-stranded RNA, has been confirmed to be involved in the development of various cancers. Considering that miRNA is also involved in a series of biological behaviors, regulating CRC occurrence and development, we review and summarize the role of miRNAs and related signaling pathways in several CRC-metastasis stages, including invasion and migration, mobility, metabolism, epithelial–mesenchymal transition, tumor-microenvironment communication, angiogenesis, anoikis, premetastatic–niche formation, and cancer stemness. In addition, we review the application of miRNAs as diagnostic CRC markers and in clinical treatment resistance. This review can contribute to understanding of the mechanism of miRNAs in CRC progression and provide a theoretical basis for clinical CRC treatment.