The Ambivalent Role of miRNAs in Carcinogenesis: Involvement in Renal Cell Carcinoma and Their Clinical Applications

The role of natural products versus miRNA in renal cell carcinoma: implications for disease mechanisms and diagnostic markers

Natural products are chemical compounds produced by living organisms. They are isolated and purified to determine their function and can potentially be used as therapeutic agents. The ability of some bioactive natural products to modify the course of cancer is fascinating and promising. In the past 50 years, there have been advancements in cancer therapy that have increased survival rates for localized tumors. However, there has been little progress in treating advanced renal cell carcinoma (RCC), which is resistant to radiation and chemotherapy. Oncogenes and tumor suppressors are two roles played by microRNAs (miRNAs). They are involved in important pathogenetic mechanisms like hypoxia and epithelial-mesenchymal transition (EMT); they control apoptosis, cell growth, migration, invasion, angiogenesis, and proliferation through target proteins involved in various signaling pathways. Depending on their expression pattern, miRNAs may identify certain subtypes of RCC or distinguish tumor tissue from healthy renal tissue. As diagnostic biomarkers of RCC, circulating miRNAs show promise. There is a correlation between the expression patterns of several miRNAs and the prognosis and diagnosis of patients with RCC. Potentially high-risk primary tumors may be identified by comparing original tumor tissue with metastases. Variations in miRNA expression between treatment-sensitive and therapy-resistant patients' tissues and serum allow for the estimation of responsiveness to target therapy. Our knowledge of miRNAs' function in RCC etiology has a tremendous uptick. Finding and validating their gene targets could have an immediate effect on creating anticancer treatments based on miRNAs. Several miRNAs have the potential to be used as biomarkers for diagnosis and prognosis. This review provides an in-depth analysis of the current knowledge regarding natural compounds and their modes of action in combating cancer. Also, this study aims to give information about the diagnostic and prognostic value of miRNAs as cancer biomarkers and their involvement in the pathogenesis of RCC.

KL is a favorable prognostic factor related immune for clear cell renal cell carcinoma

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is a prevalent cancer in adult urology, often leading to metastasis and poor prognosis. Recently, advances in tumor immunology and aging research have opened up new possibilities for the treatment of kidney cancer. Therefore, the identification of potential targets and prognostic biomarkers for immunotherapy has become increasingly urgent.

METHODS

Using GSE168845 data, we identified immune-aging-associated differentially expressed genes (IAR-DEGs) by intersecting differentially expressed immune-related genes and aging-related genes. The prognostic value of IAR-DEGs was determined via univariate and multivariate Cox regression analysis, revealing KL as an independent prognostic factor for ccRCC. We also investigated the correlation between KL and various immune-related factors, including immune cell infiltration, immune score, immune checkpoint, MSI, and TIED score. To confirm the expression of KL in ccRCC, we conducted qRT-PCR assays on both ccRCC cell lines and clinical tissue samples, and compared KL expression levels between normal kidney cell line (HK-2) and ACHN, a ccRCC cell line. Finally, we assessed KL protein expression levels in tissues using immunohistochemistry (IHC).

RESULTS

In this study, we utilized Venn diagram analysis to identify 17 co-expressed immune-aging related DEGs from GSE168845, import database, and MSigDB database. GO and KEGG analysis revealed that the functions of the 17 IAR-DEGs were primarily related to "aging". Univariate and multivariate Cox analysis validated these 17 genes, and KL was determined to be an independent prognostic factor for ccRCC. The downregulation of KL was observed in ccRCC tissues and was negatively associated with T stage, M stage, pathological stage, and histologic grade (p < 0.05). This downregulation indicated disease deterioration and a shortened overall survival period. Our calibration curves and nomogram demonstrated the excellent predictive potential of KL. GSEA analysis showed that KL gene mediated immune and aging-related pathways, and was significantly correlated with immune infiltration and MS and TIED score. More research has revealed a significant reduction in KL mRNA expression levels in human renal cancer cells, particularly in ccRCC tissues compared to adjacent normal kidney tissues. Moreover, immunohistochemistry data have demonstrated a marked decrease in KL protein expression levels in ccRCC cells when compared to adjacent normal tissues.

CONCLUSIONS

KL was a potential aging-related target for immunotherapy and valid prognostic biomarker for ccRCC patients.

Chasing the Role of miRNAs in RCC: From Free-Circulating to Extracellular-Vesicle-Derived Biomarkers

Renal cell carcinoma (RCC) is the second most common cancer of the urinary system. The current therapeutic strategies are based on partial or total nephrectomy and/or targeted therapies based on immune checkpoint inhibitors to which patients are often refractory. Preventive and screening strategies do not exist and the few available biomarkers for RCC are characterized by a lack of sensitivity, outlining the need for novel noninvasive and sensitive biomarkers for early diagnosis and better disease monitoring. Blood liquid biopsy (LB) is a non- or minimally invasive procedure for a more representative view of tumor heterogeneity than a tissue biopsy, potentially allowing the real-time monitoring of cancer evolution. Growing interest is focused on the extracellular vesicles (EVs) secreted by either healthy or tumoral cells and recovered in a variety of biological matrices, blood included. EVs are involved in cell-to-cell crosstalk transferring their mRNAs, microRNAs (miRNAs), and protein content. In particular, transferred miRNAs may regulate tumorigenesis and proliferation also impacting resistance to apoptosis, thus representing potential useful biomarkers. Here, we present the latest efforts in the identification of circulating miRNAs in blood samples, focusing on the potential use of EV-derived miRNAs as RCC diagnostic and prognostic markers.

Critical Evaluation of a microRNA-Based Risk Classifier Predicting Cancer-Specific Survival in Renal Cell Carcinoma with Tumor Thrombus of the Inferior Vena Cava

(1) Background: Clear cell renal cell carcinoma extending into the inferior vena cava (ccRCCIVC) represents a clinical high-risk setting. However, there is substantial heterogeneity within this patient subgroup regarding survival outcomes. Previously, members of our group developed a microRNA(miR)-based risk classifier—containing miR-21-5p, miR-126-3p and miR-221-3p expression—which significantly predicted the cancer-specific survival (CSS) of ccRCCIVC patients. (2) Methods: Examining a single-center cohort of tumor tissue from n = 56 patients with ccRCCIVC, we measured the expression levels of miR-21, miR-126, and miR-221 using qRT-PCR. The prognostic impact of clinicopathological parameters and miR expression were investigated via single-variable and multivariable Cox regression. Referring to the previously established risk classifier, we performed Kaplan–Meier analyses for single miR expression levels and the combined risk classifier. Cut-off values and weights within the risk classifier were taken from the previous study. (3) Results: miR-21 and miR-126 expression were significantly associated with lymphonodal status at the time of surgery, the development of metastasis during follow-up, and cancer-related death. In Kaplan–Meier analyses, miR-21 and miR-126 significantly impacted CSS in our cohort. Moreover, applying the miR-based risk classifier significantly stratified ccRCCIVC according to CSS. (4) Conclusions: In our retrospective analysis, we successfully validated the miR-based risk classifier within an independent ccRCCIVC cohort.

The Emerging Role of MicroRNAs and Autophagy Mechanism in Pancreatic Cancer Progression: Future Therapeutic Approaches

Pancreatic cancer constitutes the fourth most frequent cause of death due to malignancy in the US. Despite the new therapeutic modalities, the management of pancreatic ductal adenocarcinoma (PDAC) is considered a difficult task for clinicians due to the fact that is usually diagnosed in already advanced stages and it is relatively resistant to the current chemotherapeutic agents. The molecular background analysis of pancreatic malignant tumors, which includes various epigenetic and genetic alterations, opens new horizons for the development of novel diagnostic and therapeutic strategies. The interplay between miRNAs, autophagy pathway, and pancreatic carcinogenesis is in the spotlight of the current research. There is strong evidence that miRNAs take part in carcinogenesis either as tumor inhibitors that combat the oncogene expression or as promoters (oncomiRs) by acting as oncogenes by interfering with various cell functions such as proliferation, programmed cell death, and metabolic and signaling pathways. Deregulation of the expression levels of various miRNAs is closely associated with tumor growth, progression, and dissemination, as well as low sensitivity to chemotherapeutic agents. Similarly, autophagy despite constituting a pivotal homeostatic mechanism for cell survival has a binary role in PDAC, either as an inhibitor or promoter of carcinogenesis. The emerging role of miRNAs in autophagy gets a great deal of attention as it opens new opportunities for the development of novel therapeutic strategies for the management of this aggressive and chemoresistant malignancy. In this review, we will shed light on the interplay between miRNAs and the autophagy mechanism for pancreatic cancer development and progression.

MicroRNA-613 Enhances Nasopharyngeal Carcinoma Cell Radiosensitivity via the DNA Methyltransferase 3B/Tissue Inhibitor of Matrix Metalloproteinase-3/Signal Transducer and Activator of Transcription-1/Forkhead Box O-1 Axis

Nasopharyngeal carcinoma (NPC) is a common malignancy of the nasopharynx, and radioresistant represents the main obstacle in NPC treatment. Malignant transformation of normal cells is driven by genetic and epigenetic changes, which are primarily manifested as changes in miRNA levels and DNA methylation status. microRNA (miR)-613 plays an inhibitory role in several types of cancer. Herein, the current study sought to explore the roles of miR-613 in NPC cell radiosensitivity. miR-613 expression patterns in NPC tissues were detected, and its correlation with clinical indexes was analyzed. NP-69 and C666-1 cell lines were selected for cellular experimentation. Radioresistant cell line C666-1R was obtained by fractionated radiation. Cell viability, survival fraction, and apoptosis were detected by CCK-8, colony formation assay, and flow cytometry. The binding relation between miR-613 and DNMT3B was verified by dual-luciferase and RIP assays. miR-613 was lowly expressed in NPC tissues and cells, with lower expression levels in C666-1R than C666-1, and further correlated with lymph node metastasis, tumor size, and tumor metastasis. miR-613 overexpression reduced C666-1R cell viability and survival fraction and increased apoptosis, while C666-1 cells with silencing miR-613 presented the opposite trends. miR-613 targeted DNMT3B. miR-613 and DNMT3B overexpression led to enhanced C666-1R cell viability and survival fraction and decreased apoptosis. miR-613 reduced TIMP3 methylation and elevated TIMP3 protein level by inhibiting DNMT3B. miR-613 enhanced NPC radiosensitivity by inhibiting the DNMT3B/TIMP3/STAT1/FOXO1 pathway. Collectively, miR-613 inhibited DNMT3B, reduced TIMP3 methylation, and increased TIMP3 protein level, thus inhibiting the STAT1/FOXO1 pathway and enhancing the radiosensitivity of NPC cells.

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.

Role of Complement in Regulating Inflammation Processes in Renal and Prostate Cancers

For decades, the complement system, the central pillar of innate immune response, was recognized as a protective mechanism against cancer cells and the manipulation of complement effector functions in cancer setting offered a great opportunity to improve monoclonal antibody-based cancer immunotherapies. Similarly, cellular senescence, the process of cell cycle arrest that allow DNA and tissue repair has been traditionally thought to be able to suppress tumor progression. However, in recent years, extensive research has identified the complement system and cellular senescence as two main inducers of tumour growth in the context of chronic, persistent inflammation named inflammaging. Here, we discuss the data describing the ambivalent role of senescence in cancer with a particular focus on tumors that are strongly dependent on complement activation and can be understood by a new, senescence-related point of view: prostate cancer and renal cell carcinoma.

The Pathogenic Role of PI3K/AKT Pathway in Cancer Onset and Drug Resistance: An Updated Review

The PI3K/AKT pathway is one of the most frequently over-activated intracellular pathways in several human cancers. This pathway, acting on different downstream target proteins, contributes to the carcinogenesis, proliferation, invasion, and metastasis of tumour cells. A multi-level impairment, involving mutation and genetic alteration, aberrant regulation of miRNAs sequences, and abnormal phosphorylation of cascade factors, has been found in multiple cancer types. The deregulation of this pathway counteracts common therapeutic strategies and contributes to multidrug resistance. In this review, we underline the involvement of this pathway in patho-physiological cell survival mechanisms, emphasizing its key role in the development of drug resistance. We also provide an overview of the potential inhibition strategies currently available.