MicroRNA miR-29a Inhibits Colon Cancer Progression by Downregulating B7-H3 Expression: Potential Molecular Targets for Colon Cancer Therapy

B7-H3 at the crossroads between tumor plasticity and colorectal cancer progression: a potential target for therapeutic intervention

B7-H3 (B7 homology 3 protein) is an important transmembrane immunoregulatory protein expressed in immune cells, antigen-presenting cells, and tumor cells. Studies reveal a multifaceted role of B7-H3 in tumor progression by modulating various cancer hallmarks involving angiogenesis, immune evasion, and tumor microenvironment, and it is also a promising candidate for cancer immunotherapy. In colorectal cancer (CRC), B7-H3 has been associated with various aspects of disease progression, such as evasion of tumor immune surveillance, tumor-node metastasis, and poor prognosis. Strategies to block or interfere with B7-H3 in its immunological and non-immunological functions are under investigation. In this study, we explore the role of B7-H3 in tumor plasticity, emphasizing tumor glucose metabolism, angiogenesis, epithelial-mesenchymal transition, cancer stem cells, apoptosis, and changing immune signatures in the tumor immune landscape. We discuss how B7-H3-induced tumor plasticity contributes to immune evasion, metastasis, and therapy resistance. Furthermore, we delve into the most recent advancements in targeting B7-H3-based tumor immunotherapy as a potential approach to CRC treatment.

High expression of B7-H3 on monocyte/macrophages in tumor microenvironment promotes lung cancer progression by inhibiting apoptosis

Monocyte/macrophages constitute a significant population of tumor-infiltrating immune cells and play a crucial role in tumor growth, invasion, and metastasis. B7-H3, has immune regulatory functions, however, it is unclear whether B7-H3 expressed on monocyte/macrophages plays a significance role in tumor progression. We found B7-H3 was high-expressed on monocyte/macrophages in tumor microenvironment compared with adjacent tissues in lung cancer, and its expression level was positively correlated with the number of monocyte/macrophages. Furthermore, the expression of B7-H3 was related to clinical stage and lymph node metastasis. Moreover, miR-29a-3p negatively regulated B7-H3, and the expression of B7-H3 on THP-1-derived macrophages was regulated by secreting exosomes containing miR-29a-3p. In addition, knockdown of B7-H3 promoted macrophage apoptosis under hypoxia. Mechanistically, B7-H3 enhanced the antiapoptotic ability of macrophage by up-regulating HIF-1ɑ via activating NF-κB. Taken together, these results imply that B7-H3 as a therapeutic target could hold promise for enhancing anti-tumor immune responses in individuals diagnosed with lung cancer.

N6-methyladenosine modification of B7-H3 mRNA promotes the development and progression of colorectal cancer

B7-H3 is a common oncogene found in various cancer types. However, the molecular mechanisms underlying abnormal B7-H3 expression and colorectal cancer (CRC) progression need to be extensively explored. B7-H3 was upregulated in human CRC tissues and its abnormal expression was correlated with a poor prognosis in CRC patients. Notably, gain- and loss-of-function experiments revealed that B7-H3 knockdown substantially inhibited cell proliferation, migration, and invasion in vitro, whereas exogenous B7-H3 expression yielded contrasting results. In addition, silencing of B7-H3 inhibited tumor growth in a xenograft mouse model. Mechanistically, our study demonstrated that the N6-methyladenosine (m6A) binding protein YTHDF1 augmented B7-H3 expression in an m6A-dependent manner. Furthermore, rescue experiments demonstrated that reintroduction of B7-H3 considerably abolished the inhibitory effects on cell proliferation and invasion induced by silencing YTHDF1. Our results suggest that the YTHDF1-m6A-B7-H3 axis is crucial for CRC development and progression and may represent a potential therapeutic target for CRC treatment.

New Emerging Targets in Cancer Immunotherapy: The Role of B7-H3

Immune checkpoints (ICs) are molecules implicated in the fine-tuning of immune response via co-inhibitory or co-stimulatory signals, and serve to secure minimized host damage. Targeting ICs with various therapeutic modalities, including checkpoint inhibitors/monoclonal antibodies (mAbs), antibody-drug conjugates (ADCs), and CAR-T cells has produced remarkable results, especially in immunogenic tumors, setting a paradigm shift in cancer therapeutics through the incorporation of these IC-targeted treatments. However, the large proportion of subjects who experience primary or secondary resistance to available IC-targeted options necessitates further advancements that render immunotherapy beneficial for a larger patient pool with longer duration of response. B7-H3 (B7 Homolog 3 Protein, CD276) is a member of the B7 family of IC proteins that exerts pleiotropic immunomodulatory effects both in physiologic and pathologic contexts. Mounting evidence has demonstrated an aberrant expression of B7-H3 in various solid malignancies, including tumors less sensitive to current immunotherapeutic options, and has associated its expression with advanced disease, worse patient survival and impaired response to IC-based regimens. Anti-B7-H3 agents, including novel mAbs, bispecific antibodies, ADCs, CAR-T cells, and radioimmunotherapy agents, have exhibited encouraging antitumor activity in preclinical models and have recently entered clinical testing for several cancer types. In the present review, we concisely present the functional implications of B7-H3 and discuss the latest evidence regarding its prognostic significance and therapeutic potential in solid malignancies, with emphasis on anti-B7-H3 modalities that are currently evaluated in clinical trial settings. Better understanding of B7-H3 intricate interactions in the tumor microenvironment will expand the oncological utility of anti-B7-H3 agents and further shape their role in cancer therapeutics.

MicroRNAs and colorectal cancer: clinical potential and regulatory networks

Colorectal cancer (CRC) is a serious global health concern, with a high incidence and mortality rate. Although there have been advancements in the early detection and treatment of CRC, therapy resistance is common. MicroRNAs (miRNAs), a type of small non-coding RNA that regulates gene expression, are key players in the initiation and progression of CRC. Recently, there has been growing attention to the complex interplay of miRNAs in cancer development. miRNAs are powerful RNA molecules that regulate gene expression and have been implicated in various physiological and pathological processes, including carcinogenesis. By identifying current challenges and limitations of treatment strategies and suggesting future research directions, this review aims to contribute to ongoing efforts to enhance CRC diagnosis and treatment. It also provides a comprehensive overview of the role miRNAs play in CRC carcinogenesis and explores the potential of miRNA-based therapies as a treatment option. Importantly, this review highlights the exciting potential of targeted modulation of miRNA function as a therapeutic approach for CRC.

The role of miRNA in colorectal cancer diagnosis: A pilot study

Despite recent advances in diagnosis and treatment, colorectal cancer (CRC) remains the third most common cancer worldwide, and has both a poor prognosis and a high recurrence rate, thus indicating the need for new, sensitive and specific biomarkers. MicroRNAs (miRNAs/miRs) are important regulators of gene expression, which are involved in numerous biological processes implicated in tumorigenesis. The objective of the present study was to investigate the expression of miRNAs in plasma and tissue samples from patients with CRC, and to examine their potential as CRC biomarkers. Using reverse transcription-quantitative PCR, it was revealed that miR-29a, miR-101, miR-125b, miR-146a and miR-155 were dysregulated in the formalin-fixed paraffin-embedded tissues of patients with CRC, compared with the surrounding healthy tissue, and these miRNAs were associated with several pathological features of the tumor. Bioinformatics analysis of overlapping target genes identified AGE-RAGE signaling as a putative joint regulatory pathway. miR-146a was also upregulated in the plasma of patients with CRC, compared with the healthy control group, and had a fair discriminatory power (area under the curve, 0.7006), with 66.7% sensitivity and 77.8% specificity. To the best of our knowledge, this distinct five-miRNA deregulation pattern in tumor tissue, and upregulation of plasma miR-146a, were shown for the first time in patients with CRC; however, studies on larger patient cohorts are warranted to confirm their potential to be used as CRC diagnostic biomarkers.

Targeting B7-H3-A Novel Strategy for the Design of Anticancer Agents for Extracranial Pediatric Solid Tumors Treatment

Recent scientific data recognize the B7-H3 checkpoint molecule as a potential target for immunotherapy of pediatric solid tumors (PSTs). B7-H3 is highly expressed in extracranial PSTs such as neuroblastoma, rhabdomyosarcoma, nephroblastoma, osteosarcoma, and Ewing sarcoma, whereas its expression is absent or very low in normal tissues and organs. The influence of B7-H3 on the biological behavior of malignant solid neoplasms of childhood is expressed through different molecular mechanisms, including stimulation of immune evasion and tumor invasion, and cell-cycle disruption. It has been shown that B7-H3 knockdown decreased tumor cell proliferation and migration, suppressed tumor growth, and enhanced anti-tumor immune response in some pediatric solid cancers. Antibody-drug conjugates targeting B7-H3 exhibited profound anti-tumor effects against preclinical models of pediatric solid malignancies. Moreover, B7-H3-targeting chimeric antigen receptor (CAR)-T cells demonstrated significant in vivo activity against different xenograft models of neuroblastoma, Ewing sarcoma, and osteosarcoma. Finally, clinical studies demonstrated the potent anti-tumor activity of B7-H3-targeting antibody-radioimmunoconjugates in metastatic neuroblastoma. This review summarizes the established data from various PST-related studies, including in vitro, in vivo, and clinical research, and explains all the benefits and potential obstacles of targeting B7-H3 by novel immunotherapeutic agents designed to treat malignant extracranial solid tumors of childhood.

A Group of Tumor-Suppressive micro-RNAs Changes Expression Coordinately in Colon Cancer

MicroRNAs (miRNAs) are molecules with a role in the post-transcriptional regulation of messenger RNA, being involved in a wide range of biological and pathological processes. In the present study, we aim to characterize the behavior of a few miRNAs with roles in the cell cycle and differentiation of colon cancer (CC) cells. The present work considers miRNAs as reflections of the complex cellular processes in which they are generated, their observed variations being used to characterize the molecular networks in which they are part and through which cell proliferation is achieved. Tumoral and adjacent normal tissue samples were obtained from 40 CC patients, and the expression of miR-29a, miR-146a, miR-215 and miR-449 were determined by qRT-PCR analysis. Subsequent bioinformatic analysis was performed to highlight the transcription factors (TFs) network that regulate the miRNAs and functionally characterizes this network. There was a significant decrease in the expression of all miRNAs in tumor tissue. All miRNAs were positively correlated with each other. The analysis of the TF network showed tightly connected functional modules related to the cell cycle and associated processes. The four miRNAs are downregulated in CC; they are strongly correlated, showing coherence within the cellular network that regulates them and highlighting possible approach strategies.

MiR-29a-3p: a potential biomarker and therapeutic target in colorectal cancer

Cancer is frequently caused by microRNAs, which control post-transcriptional levels of gene expression by binding to target mRNAs. MiR-29a-3p has recently been shown to play a twofold function in the majority of malignancies, including colorectal cancer (CRC), according to mounting evidence. Here, we not only briefly summarize such connection between miR-29a-3p and cancers, but aslo primarily evaluate the miR-29a-3p expression pattern, clinical applicability, and molecular mechanisms in CRC to provide a guide for future studies. This review established the diagnostic and prognostic value of miR-29a-3p abnormalty in a variety of clinical samples for CRC. Furthermore, current molecular mechanisms of miR-29a-3p for regulating cancerous biological processes such growth, invasion, metastasis, the epithelial-mesenchymal transformation process, and immunomodulation through its upstream regulatory factors and downstream targeted genes were briefly explored. More specifically, miR-29a-3p has been linked to a few medications that have been shown to have anticancer benefits. To sum up, miR-29a-3p is a promising biomarker and prospective therapeutic target for the diagnosis and prognosis of CRC, but further research is still needed to establish a theoretical basis for more practical applications.

The Features of Immune Checkpoint Gene Regulation by microRNA in Cancer

Currently, the search for new promising tools of immunotherapy continues. In this regard, microRNAs (miRNAs) that influence immune checkpoint (IC) gene expression in tumor and T-cells and may be important regulators of immune cells are considered. MiRNAs regulate gene expression by blocking mRNA translation. An important feature of miRNA is its ability to affect the expression of several genes simultaneously, which corresponds to the trend toward the use of combination therapy. The article provides a list of miRNAs acting simultaneously on several ICs and miRNAs that, in addition to IC, can regulate the expression of targeted therapy genes. There is dependence of miRNA interactions with IC genes on the type of cancer. The analysis of the accumulated data demonstrates that only about 14% (95% CI: 9.8–20.1%) of the studied miRNAs regulate the expression of specific IC in more than one type of cancer. That is, there is tumor specificity in the miRNA action on ICs. A number of miRNAs demonstrated high efficiency in vitro and in vivo. This indicates the potential of miRNAs as promising agents for cancer immunotherapy. Additional studies of the miRNA–gene interaction features and the search for an optimal miRNA mimic structure are necessary.

Predicting miRNA-disease associations based on graph attention network with multi-source information

BACKGROUND

There is a growing body of evidence from biological experiments suggesting that microRNAs (miRNAs) play a significant regulatory role in both diverse cellular activities and pathological processes. Exploring miRNA-disease associations not only can decipher pathogenic mechanisms but also provide treatment solutions for diseases. As it is inefficient to identify undiscovered relationships between diseases and miRNAs using biotechnology, an explosion of computational methods have been advanced. However, the prediction accuracy of existing models is hampered by the sparsity of known association network and single-category feature, which is hard to model the complicated relationships between diseases and miRNAs.

RESULTS

In this study, we advance a new computational framework (GATMDA) to discover unknown miRNA-disease associations based on graph attention network with multi-source information, which effectively fuses linear and non-linear features. In our method, the linear features of diseases and miRNAs are constructed by disease-lncRNA correlation profiles and miRNA-lncRNA correlation profiles, respectively. Then, the graph attention network is employed to extract the non-linear features of diseases and miRNAs by aggregating information of each neighbor with different weights. Finally, the random forest algorithm is applied to infer the disease-miRNA correlation pairs through fusing linear and non-linear features of diseases and miRNAs. As a result, GATMDA achieves impressive performance: an average AUC of 0.9566 with five-fold cross validation, which is superior to other previous models. In addition, case studies conducted on breast cancer, colon cancer and lymphoma indicate that 50, 50 and 48 out of the top fifty prioritized candidates are verified by biological experiments.

CONCLUSIONS

The extensive experimental results justify the accuracy and utility of GATMDA and we could anticipate that it may regard as a utility tool for identifying unobserved disease-miRNA relationships.

Long Non-coding RNA CBR3 Antisense RNA 1 is Downregulated in Colorectal Cancer and Inhibits miR-29a-Mediated Cell Migration and Invasion

Although CBR3 Antisense RNA 1 (CBR3-AS1) has been characterized as an oncogenic long non-coding RNA (lncRNA) in several cancers, a recent study reported the downregulation of CBR3-AS1 in colorectal cancer (CRC). Therefore, we analyzed its role in CRC. CBR3-AS1 and microRNA-29a (miR-29a) expression in tissue samples from CRC patients were analyzed by RT-qPCR. The interaction between CBR3-AS1 and miR-29a was predicted by IntaRNA and validated by RNA pull-down assay. The location of CBR3-AS1 was analyzed by nuclear fractionation assay. CBR3-AS1 overexpression was performed to analyze its role in miR-29a expression. The roles of CBR3-AS1 and miR-29a in CRC cell migration and invasion were analyzed by Transwell assay. CBR3-AS1 was downregulated, and miR-29a was upregulated in CRC. CBR3-AS1 and miR-29a directly interacted with each other. CBR3-AS1 was localized in both nucleus and cytoplasm fractions. CBR3-AS1 overexpression failed to alter miR-29a expression but reduced its enhancing effects on cell invasion and migration. CBR3-AS1 is downregulated in CRC and inhibits miR-29a-mediated cell migration and invasion by sponging miR-29a.