A Review of Recent Research on the Role of MicroRNAs in Renal Cancer

MicroRNAs as promising diagnostic and prognostic markers for the human genitourinary cancer

Genitourinary cancer (GUC) represents more than one fifth of all human cancers. This makes the development of approaches to its early diagnosis an important task of modern biomedicine. Circulating microRNAs, short (17-25 nucleotides) non-coding RNA molecules found in human biological fluids and performing a regulatory role in the cell, are considered as promising diagnostic and prognostic biomarkers of cancers, including GUC. In this review we have considered the current state of research aimed at assessing microRNAs as biomarkers of such human GUC types as malignant tumors of the bladder, kidney, prostate, testicles, ovaries, and cervix. A special attention has been paid to studies devoted to the identification of microRNAs in urine as a surrogate "liquid biopsy" that may provide the simplest and cheapest approach to mass non-invasive screening of human GUC. The use of microRNA panels instead of single types of microRNA generally leads to higher sensitivity and specificity of the developed diagnostic tests. However, to date, work on the microRNAs assessment as biomarkers of human GUC is still of a research nature, and the further introduction of diagnostic tests based on microRNAs into practice requires successful clinical trials.

Expression of hsa-miRNA-15b, -99b, -181a and Their Relationship to Angiogenesis in Renal Cell Carcinoma

BACKGROUND

MicroRNAs (miRNAs) play a regulatory role in various human cancers. The roles of hsa-miR-15a-5p, hsa-miR-99b-5p, and hsa-miR-181a-5p have not been fully explored in the angiogenesis of renal cell carcinoma (RCC).

AIMS

The present study aimed to evaluate the expression of these miRNAs in tumorous and adjacent healthy tissues of RCC.

METHODS

Paired tumorous and adjacent normal kidney tissues from 20 patients were studied. The expression levels of hsa-miR-15b-5p, hsa-miR-99b-5p, and hsa-miR-181a-5p were quantified by TaqMan miRNA Assays. Putative targets were analyzed by qRT-PCR.

RESULTS

Significant downregulation of all three miRNAs investigated was observed in tumorous samples compared to adjacent normal kidney tissues. Spearman analysis showed a negative correlation between the expression levels of miRNAs and the pathological grades of the patients. Increased expression of vascular endothelial growth factor-A (VEGF-A) and hypoxia-inducible factor-1α (HIF-1α), a tissue inhibitor of metalloproteinases-1 (TIMP-1), was observed in tumorous samples compared to adjacent normal tissues. Depletion of tissue inhibitors of metalloproteinase-2 (TIMP-2) and metalloproteinase-2 (MMP-2) was detected compared to normal adjacent tissues. The examined miRNAs might function as contributing factors to renal carcinogenesis. However, more prospective studies are warranted to evaluate the potential role of miRNAs in RCC angiogenesis.

Clinical utility of keratin 14 expression measurement in reflecting the tumor properties and prognosis in patients with renal cell carcinoma: a study with long-term follow-up

PURPOSE

Keratin 14 (KRT14) is hypothesized to be involved in the pathogenesis of renal cell carcinoma (RCC) based on its tumorigenic role in various cancers and its relationship with the prognosis of other urinary system malignancies. This study aimed to evaluate the correlation of KRT14 with tumor properties and prognosis in RCC patients.

METHODS

Data from 180 RCC patients who received tumor resection were retrospectively reviewed. The KRT14 was assessed by immunohistochemistry (IHC) staining in tumor tissues and non-tumor tissues.

RESULTS

KRT14 was insufficiently expressed in both tumor and non-tumor tissues, with median (interquartile range) IHC score of 2.0 (0.0-3.4) and 1.0 (0.0-2.0), respectively. While it was relatively higher in tumor versus non-tumor tissues (P < 0.001). Besides, tumor KRT14 was positively correlated with the pathological grade (P = 0.038), tumor size (P = 0.012), T stage (P = 0.006), and TNM stage (P = 0.018). Interestingly, tumor KRT14 high predicted shorter accumulating recurrence-free survival (RFS) (P = 0.003) and accumulating overall survival (OS) (P = 0.001), which was further verified by the multivariate Cox's regression analysis (both P < 0.05). Furthermore, tumor KRT14 high estimated shorter RFS and OS from the Gene Expression Profiling Interactive Analysis and Human Protein ATLAS databases (all P < 0.05). Subgroup analyses indicated that the correlation of tumor KRT14 with accumulating RFS and accumulating OS was more pronounced in RCC patients with better physical status (such as age < 65 years and better eastern cooperative oncology group performance status) and higher tumor stages (such as higher pathological grade).

CONCLUSION

High KRT14 in tumor tissue could reflect an advanced tumor features and unsatisfying survival in RCC patients.

The Role MicroRNA-135a in Suppressing Tumor Growth in Kidney Cancer Through the Regulation of Phosphoprotein Phosphatase2A and the Activation of the AKT and ERK1/2 Signaling Pathways

Background: Kidney cancer is a frequently occurring malignant tumor in the urinary system, with rising morbidity and mortality rates in recent times. Developing new biomarkers and therapeutic targets is essential to improve the prognosis of patients affected by kidney cancer. In recent years, miRNAs' role in tumorigenesis and development has received growing attention. miRNAs constitute a group of small non-coding RNA molecules that regulate gene expression, affecting various biological processes, including cell proliferation, differentiation, and apoptosis. Of the many miRNAs, miR-135a plays a pivotal role in several cancers. Nevertheless, the precise mechanisms and functions concerning miR-135a in renal cancer remain incompletely understood. Therefore, this study aims to analyze the effects of miR-135a on renal cancer replication and migration and its possible mechanisms, and to provide new strategies for the diagnosis and treatment of renal cancer. Methods: Renal cell lines (ACHN, A498) with stable hyperexpression of miR-135a and reduced expression of miR-135a were constructed by lentivirus packaging. The changes of replication, clone formation and migration ability of overexpressed miR-135a and overexpressed miR-135a in ACHN and A498 renal cell lines were detected. The possible mechanism of miR-135a affecting the replication of kidney cancer was analyzed by target gene prediction, double luciferase test, Western blotting and subcutaneous tumorigenicity assay in nude mice. Results: Hyperexpression of miR-135a can inhibit kidney cancer replication, whereas miR-135a knockdown potentially enhances replication. However, neither hyperexpression nor knockdown of miR-135a affects the migration ability of kidney cancer cells. The protein expression of PP2A-B56-γ, PP2A-Cα and PP2A-Cβ in renal cell line decreased after hyperexpression of miR-135a, while the protein expression of PP2A-B56-γ, PP2A-Cα and PP2A-Cβ increased after knockdown of miR-135a. In addition, the protein expression of p-Akt and p-ERK1/2 proteins in kidney cancer cells after hyperexpression of miR-135a were down-regulated, while the protein expression of p-Akt and p-ERK1/2 were up-regulated in kidney cancer cells after knockdown of miR-135a. In subcutaneous tumor formation experiments in nude mice, tumor size within nude mice in the miR-135a group was significantly smaller than in the control group. Conclusion: MiR-135a could suppress the replication of kidney cancer by modulating PP2A and AKT, ERK1/2 signaling pathways.

N6-methyladenosine methylation in kidney injury

Multiple mechanisms are involved in kidney damage, among which the role of epigenetic modifications in the occurrence and development of kidney diseases is constantly being revealed. However, N6-methyladenosine (M6A), a well-known post-transcriptional modification, has been regarded as the most prevalent epigenetic modifications in higher eukaryotic, which is involved in various biological processes of cells such as maintaining the stability of mRNA. The role of M6A modification in the mechanism of kidney damage has attracted widespread attention. In this review, we mainly summarize the role of M6A modification in the progression of kidney diseases from the following aspects: the regulatory pattern of N6-methyladenosine, the critical roles of N6-methyladenosine in chronic kidney disease, acute kidney injury and renal cell carcinoma, and then reveal its potential significance in the diagnosis and treatment of various kidney diseases. A better understanding of this field will be helpful for future research and clinical treatment of kidney diseases.

Overview of miR-106a Regulatory Roles: from Cancer to Aging

MicroRNAs (miRNAs) comprise a class of non-coding RNA with extensive regulatory functions within cells. MiR-106a is recognized for its super-regulatory roles in vital processes. Hence, the analysis of its expression in association with diseases has attracted considerable attention for molecular diagnosis and drug development. Numerous studies have investigated miR-106 target genes and shown that this miRNA regulates the expression of some critical cell cycle and apoptosis factors, suggesting miR-106a as an ideal diagnostic and prognostic biomarker with therapeutic potential. Furthermore, the reported correlation between miR-106a expression level and cancer drug resistance has demonstrated the complexity of its functions within different tissues. In this study, we have conducted a comprehensive review on the expression levels of miR-106a in various cancers and other diseases, emphasizing its target genes. The promising findings surrounding miR-106a suggest its potential as a valuable biomolecule. However, further validation assessments and overcoming existing limitations are crucial steps before its clinical implementation can be realized.

Targeting integrin α5β1 in urological tumors: opportunities and challenges

Urological tumors, such as prostate cancer, renal cell carcinoma, and bladder cancer, have shown a significant rise in prevalence in recent years and account for a significant proportion of malignant tumors. It has been established that metastasis to distant organs caused by urological tumors is the main cause of death, although the mechanisms underlying metastasis have not been fully elucidated. The fibronectin receptor integrin α5β1 reportedly plays an important role in distant metastasis and is closely related to tumor development. It is widely thought to be an important cancer mediator by interacting with different ligands, mediating tumor adhesion, invasion, and migration, and leading to immune escape. In this paper, we expound on the relationship and regulatory mechanisms of integrin α5β1 in these three cancers. In addition, the clinical applications of integrin α5β1 in these cancers, especially against treatment resistance, are discussed. Last but not least, the possibility of integrin α5β1 as a potential target for treatment is examined, with new ideas for future research being proposed.

Role of microRNA carried by small extracellular vesicles in urological tumors

Small extracellular vesicles (sEVs) are minute vesicles secreted by various cells that are capable of transporting cargo, including microRNAs, between donor and recipient cells. MicroRNAs (miRNAs), small non-coding RNAs approximately 22 nucleotides in length, have been implicated in a wide array of biological processes, including those involved in tumorigenesis. Emerging evidence highlights the pivotal role of miRNAs encapsulated in sEVs in both the diagnosis and treatment of urological tumors, with potential implications in epithelial-mesenchymal transition, proliferation, metastasis, angiogenesis, tumor microenvironment and drug resistance. This review provides a brief overview of the biogenesis and functional mechanisms of sEVs and miRNAs, followed by a summarization of recent empirical findings on miRNAs encapsulated in sEVs from three archetypal urologic malignancies: prostate cancer, clear cell renal cell carcinoma, and bladder cancer. We conclude by underscoring the potential of sEV-enclosed miRNAs as both biomarkers and therapeutic targets, with a particular focus on their detection and analysis in biological fluids such as urine, plasma, and serum.

A novel prognostic signature for clear cell renal cell carcinoma constructed using necroptosis-related miRNAs

Background

This work aims to analyze the relationship between necroptosis-related microRNAs (miRNAs) and the prognosis of clear cell renal cell carcinoma (ccRCC).

Methods

The miRNAs expression profiles of ccRCC and normal renal tissues from The Cancer Genome Atlas (TCGA) database were used to construct a matrix of the 13 necroptosis-related miRNAs. Cox regression analysis was used to construct a signature to predict the overall survival of ccRCC patients. The genes targeted by the necroptosis-related miRNAs in the prognostic signature were predicted using miRNA databases. Gene Ontology (Go) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to investigate the genes targeted by the necroptosis-related miRNAs. The expression levels of selected miRNAs in 15 paired samples (of ccRCC tissues and adjacent normal renal tissues) were investigated using reverse transcriptase quantitative polymerase chain reaction (RT-qPCR).

Results

Six necroptosis-related miRNAs were found to differentially expressed between ccRCC and normal renal tissues. A prognostic signature consisting of miR-223-3p, miR-200a-5p, and miR-500a-3p was constructed using Cox regression analysis and risk scores were calculated. Multivariate Cox regression analysis showed that the hazard ratio was 2.0315 (1.2627–3.2685, P = 0.0035), indicating that the risk score of the signature was an independent risk factor. The receiver operating characteristic (ROC) curve showed that the signature has a favorable predictive capacity and the Kaplan-Meier survival analysis indicated that ccRCC patients with higher risk scores had worse prognoses (P < 0.001). The results of the RT-qPCR verified that all three miRNAs used in the signature were differentially expressed between ccRCC and normal tissues (P < 0.05).

Conclusion

The three necroptosis-related-miRNAs used in this study could be a valuable signature for the prognosis of ccRCC patients. Necroptosis-related miRNAs should be further explored as prognostic indicators for ccRCC.

miR-378a-3p promotes renal cell carcinoma proliferation, migration, and invasion by targeting TOB2

PURPOSE

Renal cell carcinoma (RCC) is one of the most common malignant tumors of the urinary system, which has high metastasis. MicroRNAs (miRNAs) have been reported to participate in RCC progression. The present study aimed to understand the biological role and mechanism of miR-378a-3p in RCC.

METHODS

RT-qPCR assay was used to assess miR-378a-3p and transducer of ERBB2 (TOB2) expression in RCC tissues and cell lines. CCK-8, clone formation, scratch, and transwell assays were carried out to evaluate cell proliferation, migration, and invasion. Furthermore, the target genes of miR-378a-3p were predicted by the online bioinformatics databases. Dual-luciferase reporter assay was used to validate the relationship between miR-378a-3p and TOB2.

RESULTS

miR-378a-3p was highly expressed in RCC tissues and RCC cell lines. Besides, miR-378a-3p accelerated the progression of RCC by mediating cell proliferation, migration and invasion. More importantly, TOB2 was confirmed as a potential target gene of miR-378a-3p. The results of loss-of-function experiments showed that inhibition of TOB2 reversed the inhibitory roles of miR-378a-3p inhibitor on RCC progression.

CONCLUSIONS

miR-378a-3p promoted cell proliferation, migration and invasion through regulating TOB2 in RCC, which indicated a promising target for the treatment of RCC.

Characterization of the basement membrane in kidney renal clear cell carcinoma to guide clinical therapy

Background

Renal cell carcinoma (RCC) is the most common kidney cancer in adults. According to the histological features, it could be divided into several subtypes, of which the most common one is kidney renal clear cell carcinoma (KIRC), which contributed to more than 90% of cases for RCC and usually ends with a dismal outcome. Previous studies suggested that basement membrane genes (BMGs) play a pivotal role in tumor development. However, the significance and prognostic value of BMGs in KIRC still wrap in the mist.

Methods

KIRC data were downloaded from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases. A prognostic risk score (PRS) model based on BMGs was established using univariate and least absolute shrinkage and selection operator (LASSO) and the Cox regression analysis was performed for prognostic prediction. The Kaplan-Meier analysis, univariate Cox regression, multivariate Cox regression, receiver operating characteristic (ROC) curves, nomogram, and calibration curves were utilized to evaluate and validate the PRS model. All KIRC cases were divided into the high-risk score (HRS) group and the low-risk score (LRS) group according to the median risk scores. In addition, single-sample gene set enrichment analysis (ssGSEA), immune analysis, tumor microenvironment (TME) analysis, principal component analysis (PCA), and half-maximal inhibitory concentration (IC50) were also applied. Expression levels of BMGs were confirmed by qRT-PCR in both human renal cancer cell lines and tissues.

Results

We established the BMGs-based prognostic model according to the following steps. Within the TCGA cohort, patients’ prognosis of the HRS group was significantly worse than that of the LRS group, which was consistent with the analysis results of the GEO cohort. PCA patterns were significantly distinct for LRS and HRS groups and pathological features of the HRS group were more malignant compared with the LRS group. Correlation analysis of the PRS model and TME features, such as immune cell scores, stromal cell scores, and ESTIMATE values, revealed a higher immune infiltration in the HRS group compared with the LRS group. The chemotherapeutic response was also evaluated in KIRC treatment. It showed that the HRS group exhibited stronger chemoresistance to chemotherapeutics like FR-180204, GSK1904529A, KIN001-102, and YM201636. The therapeutic reactivity of the other 27 chemotherapeutic agents was summarized as well. Furthermore, the FREM2 level was measured in both human kidney tissues and associated cell lines, which suggested that lower FREM2 expression prompts a severer pathology and clinical ending.

Conclusions

Our study showed that KIRC is associated with a unique BMG expression pattern. The risk scores related to the expression levels of 10 BMGs were assessed by survival status, TME, pathological features, and chemotherapeutic resistance. All results suggested that FREM2 could be a potential candidate for KIRC prognosis prediction. In this study, we established a valid model and presented new therapeutic targets for the KIRC prognosis prediction as well as the clinical treatment recommendation, and finally, facilitated precision tumor therapy for every single individual.

miR‑5590‑3p inhibits the proliferation and metastasis of renal cancer cells by targeting ROCK2 to inhibit proliferation, migration and invasion

The present study aimed to clarify the role of microRNA (miR)-5590-3p in the progression of renal cell carcinoma (RCC) and investigate the underlying mechanisms. The expression levels of miR-5590-3p, Rho-associated protein kinase (ROCK)2 and β-catenin in RCC cells were measured by reverse transcription-quantitative PCR and western blot analysis. Following overexpression of miR-5590-3p and ROCK2 by transfection of miR-5590-3p mimics and GV367-ROCK2, respectively, changes in the proliferation, migration and invasion of RCC cells were determined through colony-formation, wound-healing and Transwell assays, respectively. The direct binding interaction between miR-5590-3p and ROCK2, initially predicted using Targetscan, was validated by a dual-luciferase reporter assay. The results indicated that miR-5590-3p was downregulated in RCC. Overexpression of miR-5590-3p led to downregulation of ROCK2 and β-catenin and inhibited the proliferation, migration and invasion of RCC cells. The dual-luciferase reporter assay confirmed the binding relationship between miR-5590-3p and ROCK2. Of note, overexpression of ROCK2 effectively reversed the regulatory effects of miR-5590-3p on RCC cells. In conclusion, miR-5590-3p inhibits the proliferation, migration and invasion of RCC cells by targeting ROCK2, which is a potential molecular biomarker and therapeutic target for RCC.

Effects of Quantitative Nursing Combined with Psychological Intervention in Operating Room on Stress Response, Psychological State, and Prognosis of Patients Undergoing Laparoscopic Endometrial Cancer Surgery

Objective

To investigate the effects of quantitative nursing and psychological interventions on stress response, mental health, and prognosis in endometrial cancer patients having laparoscopic surgery.

Methods

The random number table approach was used to identify and split 98 patients with endometrial cancer undergoing laparoscopic surgery at our hospital's Obstetrics and Gynecology Hospital (n = 49) into observation and control groups (n = 49) from May 2020 to February 2022. Both groups received standard care in the operating room, while those in the observation group received quantitative and psychological interventions in the operating room. Both groups were compared for perioperative markers, stress indicators, coping strategies, and pain levels.

Results

In terms of age, TNM stage, or pathology, there was no statistically significant difference between the two groups (P > 0.05). Both the observation and control groups experienced statistically significant (P < 0.05) reductions in the perioperative markers of operation time, intraoperative blood loss, and overall hospital stay. Both groups' SAS and SDS scores were lower than they had been prior to surgery, but the observation group had lower scores than the control group, and these differences were statistically significant (P < 0.05). Postsurgery, the observation group's cortisol and adrenaline levels were lower than those of the control group, and both groups' levels were higher than before surgery, with statistical significance (P < 0.05) in both groups. Neither coping style nor pain level differed significantly between the two groups before surgery (P > 0.05). Postoperatively, while yield item scores were lower and faces scores were higher than the control group, the observation group's avoidance item score was lower than the control group. All with statistical significance. There were substantial differences in NRS SCORE between observers and controls.

Conclusion

After laparoscopic surgery to remove endometrial cancer, patients may benefit from the combination of quantitative nursing and psychological intervention in the operating room to alleviate postoperative anxiety and sadness and reduce stress reaction.

MiRNAs in renal cell carcinoma

MicroRNAs (miRNAs) are small RNA sequences that act as post-transcriptional regulatory genes to control many cellular processes through pairing bases with a complementary messenger RNA (mRNA). A single miRNA molecule can regulate more than 200 different transcripts and the same mRNA can be regulated by multiple miRNAs. In this review, we highlight the importance of miRNAs and collect the existing evidence on their relationship with kidney cancer.

Association of Androgenic Regulation and MicroRNAs in Acinar Adenocarcinoma of Prostate

Background: Prostate cancer represents 3.8% of cancer deaths worldwide. For most prostate cancer cells to grow, androgens need to bind to a cellular protein called the androgen receptor (AR). This study aims to demonstrate the expression of five microRNAs (miRs) and its influence on the AR formation in patients from the northern region of Brazil. Material and Methods: Eighty-four tissue samples were investigated, including nodular prostatic hyperplasia (NPH) and acinar prostatic adenocarcinoma (CaP). Five miRs (27a-3p, 124, 130a, 488-3p, and 506) were quantified using the TaqMan^® Real Time PCR method and AR was measured using Western blotting. Results: Levels of miRs 124, 130a, 488-3p, and 506 were higher in NPH samples. Conversely, in the CaP cases, higher levels of miR 27a-3p and AR were observed. Conclusion: In the future, these microRNAs may be tested as markers of CaP at the serum level. The relative expression of AR was 20% higher in patients with prostate cancer, which suggests its potential as a biomarker for prostate malignancy.

TGF‑β1 affects the renal cancer miRNome and regulates tumor cells proliferation

TGF-β1 is a pleiotropic cytokine that can either promote or inhibit cancer development and progression. It was previously found that TGF-β1 can regulate the expression of several microRNAs (miR or miRNA) involved in the progression of renal cell carcinoma (RCC). Therefore, the present study aimed to analyze the effects of TGF-β1 on the global RCC miRNome. It was found that TGF-β1 can regulate a complex network consisting of miRNAs and mRNAs involved in RCC transformation. In particular, TGF-β1 was revealed to regulate the proliferation of RCC cells while concomitantly modifying the expression of oncogenic regulators, including avian erythroblastosis virus E26 (V-Ets) oncogene homolog-1 (ETS1). In addition, TGF-β1 was demonstrated to regulate the expression of a number of miRNAs including miR-30c-5p, miR-155-5p, miR-181a-5p and miR-181b-5p. By contrast, TGF-β1 reciprocally modified the expression of genes encoding TGF-β1 receptors and SMADs, indicating a novel regulatory feedback mechanism mediated through the miRNAs. These data suggested that ETS1 served different roles in different subtypes of RCC tumors, specifically by functioning as an oncogene in clear cell RCC while as a tumor suppressor in papillary RCC.

Effects of HMGA2 gene silencing on cell cycle and apoptosis in the metastatic renal carcinoma cell line ACHN

Objective

To explore the role of high mobility group AT-hook 2 (HMGA2) in the regulation of the cell cycle and apoptosis.

Methods

The renal carcinoma cell line ACHN was transiently transfected with small interfering RNA to knock down the expression of the HMGA2 gene. Cell cycle analysis was undertaken using flow cytometry. The mRNA and protein levels of HMGA2, E2F transcription factor 1 (E2F1), cyclin D1, cyclin dependent kinase 6 (CDK6), B-cell lymphoma-2 (Bcl-2), caspase-3 and caspase-9 were analysed using reverse transcription quantitative real-time polymerase chain reaction and Western blot analysis.

Results

The mRNA and protein levels of HMGA2 were significantly higher in renal carcinoma cell lines compared with the human renal proximal tubular epithelial cell line HKC. After HMGA2 gene-specific silencing, more cells entered the G₀/G₁ phase, while fewer cells entered the G₂/M phase; and the cells exhibited early and late apoptosis. HMGA2 gene-specific silencing significantly reduced the mRNA and protein levels of E2F1, cyclin D1, CDK6 and Bcl-2; and increased the mRNA and protein levels of caspase-3 and caspase-9.

Conclusion

The HMGA2 gene may be involved in the tumorigenesis and development of renal cancer, thus inhibiting HMGA2 gene expression might provide a potential therapeutic target in the future.

Epigenetic inactivation of ACAT1 promotes epithelial-mesenchymal transition of clear cell renal cell carcinoma

BACKGROUND

Acetyl-CoA acyltransferase 1 (ACAT1) is a key enzyme catalyzing the production of mitochondrial ketone bodies. We have shown that ACAT1 is down-regulated in kidney renal clear cell carcinoma (KIRC) previously.

OBJECTIVE

To investigate the reasons for downregulation of ACAT1 in KIRC and explore the underlying mechanisms involved in metastatic inhibition regulated by ACAT1.

METHODS

The Gene Expression Omnibus (GEO) database was queried for meta-analysis of ACAT1 mRNA expression in KIRC. The UALCAN website was used to compare the methylation levels of the ACAT1 promoter region in KIRC and normal tissues. RT-qPCR was used to quantitate ACAT1 transcription levels. The GCBI and Tarbase V.8 databases were used to predict miRNAs that may target the mRNA of ACAT1. The correlation between mRNA expression of ACAT1, MMP7 (matrix metallopeptidase 7), CDH1 (E-cadherin), EpCAM (epithelial cell adhesion molecule), and VIM (vimentin) was analyzed. Extracellular MMP7 protein was quantitated using an ELISA assay.

RESULTS

The methylation level of the ACAT1 promoter region in KIRC was significantly higher than that in the normal kidney tissues. The ACAT1 mRNA expression in the KIRC cell lines was restored after treatment with 5-aza-dC (p < 0.05). MiR-21-5p is a conserved microRNA targeting ACAT1. It is expressed at a significantly higher level in KIRC than in normal tissues (p < 0.001). MiR-21-5p miRNA expression negatively correlates with ACAT1 mRNA expression. The expression of miR-21-5p is higher at the T3-T4 stages and in the histologic grades G3-G4. Patients with high miR-21-5p expression tended to have lower overall survival, suggesting that miR-21-5p could serve as a potentially valuable diagnostic biomarker for KIRC (AUC = 0.957; p < 0.001). A mimetic of miR-21-5p inhibited the expression of ACAT1 mRNA and protein. In addition, ACAT1 mRNA expression positively correlates with CDH1 and EpCAM but is negatively correlated with VIM. Overexpression of ACAT1 suppresses the secretion of MMP7 in KIRC cells.

CONCLUSION

Expression of ACAT1 in KIRC is controlled at two levels, firstly by the hypermethylation of the ACAT1 promoter region and secondly by overexpression of miR-21-5p. Downregulation of ACAT1 expression correlates with epithelial-mesenchymal transition (EMT).