PI3K/AKT/mTOR Dysregulation and Reprogramming Metabolic Pathways in Renal Cancer: Crosstalk with the VHL/HIF Axis

Decoding PTEN regulation in clear cell renal cell carcinoma: Pathway for biomarker discovery and therapeutic insights

Renal cell carcinoma is the most common adult renal solid tumor and the deadliest urological cancer, with clear cell renal cell carcinoma (ccRCC) being the predominant subtype. The PI3K/AKT signaling pathway assumes a central role in ccRCC tumorigenesis, wherein its abnormal activation confers a highly aggressive phenotype, leading to swift resistance against current therapies and distant metastasis. Thus, treatment resistance and disease progression remain a persistent clinical challenge in managing ccRCC effectively. PTEN, an antagonist of the PI3K/AKT signaling axis, emerges as a crucial factor in tumor progression, often experiencing loss or inactivation in ccRCC, thereby contributing to elevated mortality rates in patients. Therefore, understanding the molecular mechanisms underlying PTEN suppression in ccRCC tumors holds promise for the discovery of biomarkers and therapeutic targets, ultimately enhancing patient monitoring and treatment outcomes. The present review aims to summarize these mechanisms, emphasizing their potential prognostic, predictive, and therapeutic value in managing ccRCC.

PLAUR facilitates the progression of clear cell renal cell carcinoma by activating the PI3K/AKT/mTOR signaling pathway

Background

PLAUR has been found upregulated in various tumors and closely correlated with the malignant phenotype of tumor cells. The aim of this study was to investigate the relationship between PLAUR and clear cell renal cell carcinoma (ccRCC) and its potential mechanism of promoting tumor progression.

Methods

The expression levels and clinical significance of PLAUR, along with the associated signaling pathways, were extensively investigated in ccRCC samples obtained from The Cancer Genome Atlas (TCGA). PLAUR expression in 20 pairs of ccRCC tumor tissues and the adjacent tissues was assessed using qRT-PCR and IHC staining. Additionally, a series of in vitro experiments were conducted to investigate the impact of PLAUR suppression on cellular proliferation, migration, invasion, cell cycle progression, and apoptosis in ccRCC. The Western blot analysis was employed to investigate the expression levels of pivotal genes associated with the PI3K/AKT/mTOR signaling pathway.

Results

The expression of PLAUR was significantly upregulated in ccRCC compared to normal renal tissues, and higher PLAUR expression in ccRCC was associated with a poorer prognosis than low expression. The in-vitro functional investigations demonstrated that knockdown of PLAUR significantly attenuated the proliferation, migration, and invasion capabilities of ccRCC cells. Concurrently, PLAUR knockdown effectively induced cellular apoptosis, modulated the cell cycle, inhibited the EMT process, and attenuated the activation of the PI3K/AKT/mTOR signaling pathway. PLAUR may represent a key mechanism underlying ccRCC progression.

Conclusions

The involvement of PLAUR in ccRCC progression may be achieved through the activation of the PI3K/AKT/mTOR signaling pathway, making it a reliable biomarker for the identification and prediction of ccRCC.

Targeting PI3K/AKT/mTOR signaling to overcome drug resistance in cancer

This review comprehensively explores the challenge of drug resistance in cancer by focusing on the pivotal PI3K/AKT/mTOR pathway, elucidating its role in oncogenesis and resistance mechanisms across various cancer types. It meticulously examines the diverse mechanisms underlying resistance, including genetic mutations, feedback loops, and microenvironmental factors, while also discussing the associated resistance patterns. Evaluating current therapeutic strategies targeting this pathway, the article highlights the hurdles encountered in drug development and clinical trials. Innovative approaches to overcome resistance, such as combination therapies and precision medicine, are critically analyzed, alongside discussions on emerging therapies like immunotherapy and molecularly targeted agents. Overall, this comprehensive review not only sheds light on the complexities of resistance in cancer but also provides a roadmap for advancing cancer treatment.

Involvement of lncRNAs in the regulation of aerobic glycolysis in hepatocellular carcinoma: Main functions, regulatory mechanisms and potential therapeutic implications (Review)

Even under aerobic conditions, tumor cells can reprogram their metabolism to preferentially metabolize glucose into lactic acid. This abnormal metabolic pattern, known as the 'Warburg' effect or aerobic glycolysis, promotes cancer progression. Long non‑coding RNAs (lncRNAs) are RNAs that are >200 nucleotides in length and do not have protein‑coding capabilities. However, these RNAs play a key role in tumor development. There is increasing evidence to indicate that lncRNAs regulate glucose metabolism in tumor cells by affecting metabolic enzymes and some signaling pathways, thereby regulating the occurrence and progression of hepatocellular carcinoma (HCC). Therefore, it is crucial to understand which lncRNAs play a regulatory role in HCC glycolysis and to determine the related molecular mechanisms. The present review summarized and discussed the functions of lncRNAs, focusing on the regulatory mechanisms of lncRNAs in the process of glycolysis in HCC. In addition, the present review suggests the importance of lncRNAs as future therapeutic targets for antitumor cell metabolism.

Circulating microRNA-155-3p levels predicts response to first line immunotherapy in patients with metastatic renal cell carcinoma

Predictive biomarkers of response to immune checkpoint-based therapies (ICI) remain a critically unmet need in the management of advanced renal cell carcinoma (RCC). The complex interplay of the tumour microenvironment (TME) and the circulating immune response has proven to be challenging to decipher. MicroRNAs have gained increasing attention for their role in post-transcriptional gene expression regulation, particularly because they can have immunomodulatory properties. We evaluated the presence of immune-specific extracellular vesicle (EV) microRNAs in the plasma of patients with metastatic RCC (mRCC) prior to initiation of ICI. We found significantly lower levels of microRNA155-3p (miR155) in responders to ICI, when compared to non-responders. This microRNA has unique immunomodulatory properties, thus providing potential biological rationale for our findings. Our results support further work in exploring microRNAs as potential biomarkers of response to immunotherapy.

Clinical research progress of ridaforolimus (AP23573, MK8668) over the past decade: a systemic review

Rapamycin, an established mTOR inhibitor in clinical practice, is widely recognized for its therapeutic efficacy. Ridaforolimus, a non-prodrug rapalog, offers improved aqueous solubility, stability, and affinity compared to rapamycin. In recent years, there has been a surge in clinical trials involving ridaforolimus. We searched PubMed for ridaforolimus over the past decade and selected clinical trials of ridaforolimus to make a summary of the research progress of ridaforolimus in clinical trials. The majority of these trials explored the application of ridaforolimus in treating various tumors, including endometrial cancer, ovarian cancer, prostate cancer, breast cancer, renal cell carcinoma, and other solid tumors. These trials employed diverse drug combinations, incorporating agents such as ponatinib, bicalutamide, dalotuzumab, MK-2206, MK-0752, and taxanes. The outcomes of these trials unveiled the diverse potential applications of ridaforolimus in disease treatment. Our review encompassed analyses of signaling pathways, ridaforolimus as a single therapeutic agent, its compatibility in combination with other drugs, and an assessment of adverse events (AEs). We conclude by recommending further research to advance our understanding of ridaforolimus's clinical applications.

miR-1182-mediated ALDH3A2 inhibition affects lipid metabolism and progression in ccRCC by activating the PI3K-AKT pathway

In clear cell renal cell carcinoma (ccRCC), dysregulated lipid metabolism plays a pivotal role in tumor initiation and progression. This study delves into the unexplored landscape of Dysregulated Aldehyde Dehydrogenase 3 Family Member A2 (ALDH3A2) in ccRCC. Using a combination of "fatty acid metabolism" dataset analysis and differentially expressed genes (DEGs) derived from Gene Expression Omnibus (GEO) database, potential metabolic regulators in ccRCC were identified. Subsequent investigations utilizing public databases, clinical samples, and in vitro experiments revealed that ALDH3A2 was down-regulated in ccRCC, mediated by miR-1182, highlighting its role as an independent prognostic factor for patient survival. Functionally, ALDH3A2 exhibited tumor-suppressive properties, impacting ccRCC cell phenotypes and influencing epithelial-mesenchymal transition. Mechanistically, silencing ALDH3A2 promoted lipid accumulation in ccRCC cells by activating the PI3K-AKT pathway, thereby promoting tumor progression. These findings shed light on the critical role of the miR-1182/ALDH3A2 axis in ccRCC tumorigenesis, emphasizing the potential for targeting lipid metabolism as a promising anti-cancer strategy.

The Impact of 8 Weeks of Combined Physical Exercise Training on SIRT3 and mTOR in Lymphocytes, and on Lipid Peroxidation

The sirtuins (SIRT) protein family and the mechanistic/mammalian target of rapamycin (mTOR) are intracellular molecules that have been involved in the regulation of several biological processes, as well as in various aging-related processes. This pilot study, in small scale, aimed to analyze the effects of an 8-week physical exercise program on SIRT3 and mTOR levels in lymphocytes, as well as on lipid peroxidation in middle aged and older men. A total of 9 participants aged between 56 and 73 years were enrolled in an 8-week physical exercise program comprising cardiovascular and high-intensity interval training. The program involved three sessions per week, each lasting 45-60 min, conducted on non-consecutive days. Tests were conducted before and after the experimental period (pre- and post-training). Assessments included a vertical jump, 20 m velocity, ball throwing, and an aerobic capacity test. Lipid peroxidation (MDA) was measured in plasma as an oxidative stress biomarker. Additionally, sirtuin 3 (SIRT3/β-actin) and mTOR (mTOR/β-actin) levels were measured in isolated lymphocytes extracted from venous blood. Following the exercise training period, our results demonstrated a significant improvement in aerobic capacity (pre-training: 615.4 ± 45.3 m; post-training: 687.2 ± 34.6 m; t = -2.521; p = 0.012) and 20 m velocity (pre-training: 4.6 ± 0.5 s; post-training: 4.3 ± 0.3 s; t = -2.023; p = 0.04). Concerning blood variables, there was a significant decrease in mTOR levels (pre-training: 0.857 ± 0.593; post-training: 0.214 ± 0.097; t = -2.547; p = 0.011), while no changes were observed in SIRT3 (pre-training: 0.608 ± 0.404; post-training: 0.516 ± 0.390; t = 0.533; p = 0.594) and MDA (pre-training: 8420 ± 4615; post-training: 8800 ± 3163; t = -0.533; p = 0.594). The notable reduction in mTOR levels in lymphocytes following the 8-week physical exercise program suggests a potential role of exercise in modulating immune cell dynamics, particularly in middle-aged and older individuals. Furthermore, the exercise regimen resulted in improvements in physical function, including enhanced aerobic capacity and walking velocity.

ZNF471 Interacts with BANP to Reduce Tumour Malignancy by Inactivating PI3K/AKT/mTOR Signalling but is Frequently Silenced by Aberrant Promoter Methylation in Renal Cell Carcinoma

Background: Renal cell carcinoma (RCC) is one of the most common malignant tumours of the urinary system. However, the aetiology and pathogenesis of RCC remain unclear. The C2H2 zinc finger protein (ZNF) family is the largest transcriptional regulatory factor family found in mammals, and Krüppel-associated box domain-containing zinc finger proteins (KRAB-ZFPs) constitute the largest subfamily of the C2H2 zinc finger protein family and play an important role in the occurrence and development of tumours. The aim of this study was to explore the role of abnormal methylation of ZNF471 in the development of renal carcinoma. Methods: In this study, we first used the TCGA and EWAS Data Hub databases to analyse the expression and methylation levels of ZNF471 in renal carcinoma tissues and adjacent normal tissues. Second, we collected samples of renal cancer and adjacent normal tissues at Peking University First Hospital to investigate the expression and methylation level of ZNF471 in renal cancer tissues and the relationships between these levels and the clinicopathological features and prognosis of patients with renal cancer. Next, we investigated the effects of ZNF471 on the proliferation, metastasis, cell cycle progression, and apoptosis of renal cell carcinoma cells by cell biology experiments. Finally, we elucidated the underlying molecular mechanisms of ZNF471 in renal cell carcinoma by transcriptome sequencing, bioinformatics analysis and molecular biology experiments. Results: The expression of ZNF471 in renal carcinoma tissues and cell lines was significantly lower than that in adjacent normal tissues and cell lines due to abnormal promoter CpG methylation. Furthermore, the expression of ZNF471 in renal carcinoma tissues was negatively correlated with tumour stage and grade in patients with renal carcinoma. The results of the cell biology experiments showed that ZNF471 could significantly inhibit the proliferation, migration and cell cycle progression of renal cell carcinoma cells and promote apoptosis in these cells. In addition, ZNF471 could interact with BANP and suppress the malignant phenotype of RCC by inactivating the PI3K/AKT/mTOR signalling pathway. Conclusions: As an important tumour suppressor, ZNF471 can interact with BANP in renal cancer cells and inhibit the activation of the PI3K/AKT/mTOR signalling pathway, thereby inhibiting the occurrence and development of renal cancer.

Genetic and Epigenetic Characteristics in Isolated Pancreatic Metastases of Clear-Cell Renal Cell Carcinoma

Isolated pancreatic metastases of renal cell carcinoma (IsPMRCC) are a rare manifestation of metastatic, clear-cell renal cell carcinoma (RCC) in which distant metastases occur exclusively in the pancreas. In addition to the main symptom of the isolated occurrence of pancreatic metastases, the entity surprises with additional clinical peculiarities: (a) the unusually long interval of about 9 years between the primary RCC and the onset of pancreatic metastases; (b) multiple pancreatic metastases occurring in 36% of cases; (c) favourable treatment outcomes with a 75% 5-year survival rate; and (d) volume and growth-rate dependent risk factors generally accepted to be relevant for overall survival in metastatic surgery are insignificant in isPMRCC. The genetic and epigenetic causes of exclusive pancreatic involvement have not yet been investigated and are currently unknown. Conversely, according to the few available data in the literature, the following genetic and epigenetic peculiarities can already be identified as the cause of the protracted course: 1. high genetic stability of the tumour cell clones in both the primary tumour and the pancreatic metastases; 2. a low frequency of copy number variants associated with aggressiveness, such as 9p, 14q and 4q loss; 3. in the chromatin-modifying genes, a decreased rate of PAB1 (3%) and an increased rate of PBRM1 (77%) defects are seen, a profile associated with a favourable course; 4. an increased incidence of KDM5C mutations, which, in common with increased PBRM1 alterations, is also associated with a favourable outcome; and 5. angiogenetic biomarkers are increased in tumour tissue, while inflammatory biomarkers are decreased, which explains the good response to TKI therapy and lack of sensitivity to IT.

PI3K/AKT/mTOR signaling transduction pathway and targeted therapies in cancer

The PI3K/AKT/mTOR (PAM) signaling pathway is a highly conserved signal transduction network in eukaryotic cells that promotes cell survival, cell growth, and cell cycle progression. Growth factor signalling to transcription factors in the PAM axis is highly regulated by multiple cross-interactions with several other signaling pathways, and dysregulation of signal transduction can predispose to cancer development. The PAM axis is the most frequently activated signaling pathway in human cancer and is often implicated in resistance to anticancer therapies. Dysfunction of components of this pathway such as hyperactivity of PI3K, loss of function of PTEN, and gain-of-function of AKT, are notorious drivers of treatment resistance and disease progression in cancer. In this review we highlight the major dysregulations in the PAM signaling pathway in cancer, and discuss the results of PI3K, AKT and mTOR inhibitors as monotherapy and in co-administation with other antineoplastic agents in clinical trials as a strategy for overcoming treatment resistance. Finally, the major mechanisms of resistance to PAM signaling targeted therapies, including PAM signaling in immunology and immunotherapies are also discussed.