RNA methylation, a prevalent post-transcriptional modification, has garnered considerable attention in research circles. It exerts regulatory control over diverse biological functions by modulating RNA splicing, translation, transport, and stability. Notably, studies have illuminated the substantial impact of RNA methylation on tumor immunity. The primary types of RNA methylation encompass N6-methyladenosine (m6A), 5-methylcytosine (m5C), N1-methyladenosine (m1A), and N7-methylguanosine (m7G), and 3-methylcytidine (m3C). Compelling evidence underscores the involvement of RNA methylation in regulating the tumor microenvironment (TME). By affecting RNA translation and stability through the "writers", "erasers" and "readers", RNA methylation exerts influence over the dysregulation of immune cells and immune factors. Consequently, RNA methylation plays a pivotal role in modulating tumor immunity and mediating various biological behaviors, encompassing proliferation, invasion, metastasis, etc. In this review, we discussed the mechanisms and functions of several RNA methylations, providing a comprehensive overview of their biological roles and underlying mechanisms within the tumor microenvironment and among immunocytes. By exploring how these RNA modifications mediate tumor immune evasion, we also examine their potential applications in immunotherapy. This review aims to provide novel insights and strategies for identifying novel targets in RNA methylation and advancing cancer immunotherapy efficacy.
1 January 2022 in International Journal of Biological Sciences
Hepatocellular carcinoma (HCC) is one of the most lethal tumors in China and worldwide, although first-line therapies for HCC, such as atezolizumab and bevacizumab, have been effective with good results, the researches on new therapies have attracted much attention. With the deepening research on tumor immunology, the role and operation mechanism of immune cells in the tumor microenvironment (TME) of HCC have been explained, such as programmed cell death protein 1 (PD-1) binding to ligand could cause T cell exhaustion and reduce IFN-γ T cell secretion, cytotoxic T lymphocyte 4 (CTLA-4) and CD28 mediate immunosuppression by competing for B7 protein and disrupting CD28 signal transduction pathway, which also lays the foundation for the development and application of more new immune checkpoint inhibitors (ICIs). The biological behavior of various immune checkpoints has been proved in HCC, such as PD-1, programmed cell death ligand 1 (PD-L1), CTLA-4 and so on, leading to a series of clinical trials. Currently, FDA approved nivolumab, pembrolizumab and nivolumab plus ipilimumab for the treatment of HCC. However, the treatment of ICI has the disadvantages of low response rate and many side effects, so the combination of ICIs and various other therapies (such as VEGF or VEGFR inhibition, neoadjuvant and adjuvant therapy, locoregional therapies) has been derived. Further studies on immune checkpoint mechanisms may reveal new therapeutic targets and new combination therapies in the future.
The prognosis of colorectal cancer (CRC) is largely dependent on the early detection of hepatic metastases. With the advantages of nonradioactivity and the availability of multiple scanning sequences, the efficacy of magnetic resonance imaging (MRI) in the detection of colorectal liver metastases (CRLM) is not yet clear. We performed this meta-analysis to address this issue. PubMed, Embase, and the Cochrane Library were searched for studies reporting diagnostic performance of MRI for CRLM. Descriptive and quantitative data were extracted. The study quality was evaluated for the identified studies and a random effects model was used to determine the integrated diagnosis estimation. Meta-regression and subgroup analyses were implemented to investigate the potential contributors to heterogeneity. As a result, seventeen studies were included for analysis (from the year 1996 to 2018), comprising 1121 patients with a total of 3279 liver lesions. The pooled sensitivity, specificity, and diagnostic odds ratio were 0.90 (95% confidence intervals (CI): 0.81–0.95), 0.88 (0.80–0.92), and 62.19 (23.71–163.13), respectively. The overall weighted area under the curve was 0.94 (0.92–0.96). Using two or more imaging planes and a quantitative/semiquantitative interpretation method showed higher diagnostic performance, although only the latter demonstrated statistical significance (P < 0.05). Advanced scanning sequences with DWI and liver-specific contrast media tended to increase the sensitivity for CRLM detection. We therefore concluded that contemporary MRI has high sensitivity and specificity for screening CRLM, especially for those with advanced scanning sequences. Using two or more imaging planes and adopting a quantitative/semiquantitative imaging interpretation may further improve diagnosis. However, the MRI results should be interpreted with caution because of substantial heterogeneity among studies.
Cancer immune checkpoint inhibitors (ICIs) have brought breakthroughs, but only about one‐third of cancer patients benefit from ICIs. In recent years, targeting non‐apoptotic regulated cell death (RCD) subtypes, such as ferroptosis, necroptosis, autophagy, cuproptosis, and pyroptosis, has emerged as a novel strategy in cancer therapy due to their ability to release damage‐associated molecular patterns (DAMPs), enhance antigen presentation, and remodel the tumor immune microenvironment, thereby activating anti‐tumor immune responses. A number of studies have shown that precise induction of these pathways by small molecules or nanoparticles can reverse the resistance to chemoradiotherapy and ICIs, promote the transformation of “cold tumors” to “hot tumors,” and ultimately establish durable immune memory. This article systematically reviewed the key mechanisms and immunomodulatory functions of five types of non‐apoptotic RCD (ferroptosis, necroptosis, autophagy, cuproptosis, and pyroptosis), discussed the related treatment strategies, and prospects for the future application in combination with existing immunotherapy.
The lncRNA tumor suppressor candidate 8 (TUSC8) plays a critical role in the development of several cancers. However, the biological functions and underlying molecular mechanisms of TUSC8 with respect to breast cancer remain largely unclear. Here, we found that TUSC8 was significantly down-regulated in breast cancer tissues and its high expression predicted better prognosis of breast cancer patients. Functionally, knock-down of TUSC8 drastically promoted the proliferation, migration and invasion of breast cancer cells in vitro and facilitated tumorigenicity and metastasis in vivo. Mechanistically, the results of luciferase reporter, RIP and RNA pull-down assays proved that TUSC8 functioned as molecular sponge for miR-190b-5p. Furthermore, we showed that TUSC8 served as a competing endogenous RNA (ceRNA) of myosin regulatory light chain interacting protein (MYLIP) through competitively binding with miR-190b-5p and suppressed breast cancer metastasis through regulating the expression of epithelial-mesenchymal transition (EMT) related markers. Clinically, the receiver operating characteristic curve (ROC) analyses revealed that the combination usage of TUSC8 and MYLIP might become novel promising diagnostic biomarkers for breast cancer. Taken together, these results suggested that TUSC8 inhibited breast cancer growth and metastasis via miR-190b-5p/MYLIP axis, providing us new insights into developing potential therapeutic targets for breast cancer patients.