Epithelial to Mesenchymal Transition in Renal Cell Carcinoma: Implications for Cancer Therapy

Circular RNA AGAP1 Stimulates Immune Escape and Distant Metastasis in Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most representative subtype of renal cancer, with a highly aggressive phenotype and extremely poor prognosis. Immune escape is one of the main reasons for ccRCC growth and metastasis, in which circular RNAs (circRNAs) play critical roles. Therefore, this research studied circAGAP1-associated mechanisms in immune escape and distant metastasis in ccRCC. circAGAP1/miR-216a-3p/MKNK2 was overexpressed or down-regulated by cell transfection. EdU assay, colony formation assay, scratch assay, Transwell assay, immunoblotting, and flow cytometry were used to evaluate cell proliferation, migration, invasion, EMT, and immune escape, respectively. Dual-luciferase reporting assay and RIP assay were used to evaluate the targeting relationship between circAGAP1/miR-216a-3p/MKNK2. Xenotransplantation in nude mice was used to evaluate the growth of ccRCC tumors in vivo. Here, circAGAP1 high expression was positively correlated with higher histological grade and distant metastasis and was a prognostic indicator for ccRCC. Depleting circAGAP1 effectively hampered the proliferative, invasive, and migratory capacities, EMT, and immune escape of ccRCC cells. Correspondingly, silencing circAGAP1 delayed tumor growth, distant metastasis, and immune escape in vivo. Mechanistically, circAGAP1 sponged the tumor suppressor miR-216a-3p, thereby preventing miR-216a-3p from inhibiting MAPK2. Collectively, our findings demonstrate that circAGAP1 exerts a tumor suppressor function through miR-216a-3p/MKNK2 during the immune escape and distant metastasis in ccRCC, and suggest that circAGAP1 may be a novel prognostic marker and therapeutic target for ccRCC.

Diagnostic and prognostic value of circulating tumor cells in renal cell cancer: A systematic review and meta-analysis

Renal cell carcinoma (RCC) is a type of tumor with high morbidity and recurrence rates. The application of circulating tumor cells (CTCs) in RCC remains controversial. Hence, we performed a meta-analysis to elucidate the diagnostic and prognostic value of CTCs in RCC. To obtain a precise conclusion, a systematic search was conducted in Pubmed, Cochrane Database, Embase and Web of Science up to Dec 01, 2022. We also further identified the references in relevant studies. The diagnostic accuracy variables (sensitivity, specificity) and odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were used to access precise of CTCs and relationship between CTCs and disease stages, respectively. Heterogeneity test, sensitivity analysis, meta-regression and publishing bias were also applied. A total of 12 studies involving 767 patients were considered to be included in the final meta-analysis. The results revealed that the overall sensitivity, specificity of CTC detection in RCC were 45% (95%CI, 32-60%) and 99% (95%CI, 97-100%), respectively. In subgroup analysis, diagnostic sensitivity of CTCs in clear cell renal cell carcinoma (ccRCC) (69%, 95%CI; 50-88%) was significantly higher than other RCC subtypes (34%, 95%CI; 21-48%) (p<0.05). Meanwhile, advanced diseases (stage III-IV) were more likely to find CTCs than localized diseases (stage I-II) (OR, 2.29; 95%CI, 1.37-3.83; p = 0.002). This systematic review and meta-analysis demonstrated that CTC detection could be considered as a promising auxiliary diagnostic and staging method for RCC, especially ccRCC subtype. Meanwhile, the presence of cytokeratin-positive CTCs is highly likely associated with increased risk of poor prognosis in RCC.

Abnormal expression of FOXM1 in carcinogenesis of renal cell carcinoma: From experimental findings to clinical applications

Renal cell carcinoma (RCC) is a prevalent malignancy within the genitourinary system. At present, patients with high-grade or advanced RCC continue to have a bleak prognosis. Mounting research have emphasized the significant involvement of Forkhead box M1 (FOXM1) in RCC development and progression. Therefore, it is imperative to consolidate the existing evidence regarding the contributions of FOXM1 to RCC tumorigenesis through a comprehensive review. This study elucidated the essential functions of FOXM1 in promoting RCC growth, invasion, and metastasis by regulating cell cycle progression, DNA repair, angiogenesis, and epithelial-mesenchymal transition (EMT). Also, FOXM1 might serve as a novel diagnostic and prognostic biomarker as well as a therapeutic target for RCC. Clinical findings demonstrated that the expression of FOXM1 was markedly upregulated in RCC samples, while a high level of FOXM1 was found to be associated with a poor overall survival rate of RCC. Furthermore, it is worth noting that FOXM1 may have a significant impact on the resistance of renal cell carcinoma (RCC) to radiotherapy. This observation suggests that inhibiting FOXM1 could be a promising strategy to impede the progression of RCC and enhance its sensitivity to radiotherapy. The present review highlighted the pivotal role of FOXM1 in RCC development. FOXM1 has the capacity to emerge as not only a valuable diagnostic and prognostic tool but also a viable therapeutic option for unresectable RCC.

Mechanisms of tyrosine kinase inhibitor resistance in renal cell carcinoma

Renal cell carcinoma (RCC), the most prevalent type of kidney cancer, is a significant cause of cancer morbidity and mortality worldwide. Antiangiogenic tyrosine kinase inhibitors (TKIs), in combination with immune checkpoint inhibitors (ICIs), are among the first-line treatment options for patients with advanced RCC. These therapies target the vascular endothelial growth factor receptor (VEGFR) tyrosine kinase pathway and other kinases crucial to cancer proliferation, survival, and metastasis. TKIs have yielded substantial improvements in progression-free survival (PFS) and overall survival (OS) for patients with advanced RCC. However, nearly all patients eventually progress on these drugs as resistance develops. This review provides an overview of TKI resistance in RCC and explores different mechanisms of resistance, including upregulation of alternative proangiogenic pathways, epithelial-mesenchymal transition (EMT), decreased intracellular drug concentrations due to efflux pumps and lysosomal sequestration, alterations in the tumor microenvironment including bone marrow-derived cells (BMDCs) and tumor-associated fibroblasts (TAFs), and genetic factors such as single nucleotide polymorphisms (SNPs). A comprehensive understanding of these mechanisms opens the door to the development of innovative therapeutic approaches that can effectively overcome TKI resistance, thereby improving outcomes for patients with advanced RCC.

Construction of EMT related prognostic signature for kidney renal clear cell carcinoma, through integrating bulk and single-cell gene expression profiles

Introduction: Kidney renal clear cell carcinoma (KIRC), as a main type of malignant kidney cancers, has a poor prognosis. Epithelial-mesenchymal transformation (EMT) exerts indispensable role in tumor progression and metastasis, including in KIRC. This study aimed to mine more EMT related details and build prognostic signature for KIRC. Methods: The KIRC scRNA-seq data and bulk data were downloaded from GEO and TCGA databases, respectively. The cell composition in KIRC was calculated using CIBERSORT. Univariate Cox regression analysis and LASSO Cox regression analysis were combined to determine the prognostic genes. Gene set variation analysis and cell-cell communication analysis were conducted to obtain more functional information. Additionally, functional analyses were conducted to determine the biological roles of si-LGALS1 in vitro. Results: We totally identified 2,249 significant differentially expressed genes (DEGs) in KIRC samples, meanwhile a significant distinct expression pattern was found in KIRC, involving Epithelial Mesenchymal Transition pathway. Among all cell types, significantly higher proportion of epithelial cells were observed in KIRC, and 289 DEGs were identified in epithelial cells. After cross analysis of all DEGs and 970 EMT related genes, SPARC, TMSB10, LGALS1, and VEGFA were optimal to build prognostic model. Our EMT related showed good predictive performance in KIRC. Remarkably, si-LGALS1 could inhibit migration and invasion ability of KIRC cells, which might be involved in suppressing EMT process. Conclusion: A novel powerful EMT related prognostic signature was built for KIRC patients, based on SPARC, TMSB10, LGALS1, and VEGFA. Of which, si-LGALS1 could inhibit migration and invasion ability of KIRC cells, which might be involved in suppressing EMT process.

Formin-related protein 1 facilitates proliferation and aggressive phenotype of clear cell renal cell carcinoma through MAPK/MMP2 pathway

BACKGROUND

Formin-related protein-1(FRL1) has reportedly been overexpressed in a variety of malignancies, such as clear cell renal cell carcinoma (ccRCC). However, the clinical value and molecular mechanisms underlying ccRCC tumorigenesis and progression in association with FRL1 remain poorly understood.

METHODS

Immunohistochemical analysis was performed on 119 paraffin-embedded RCC tissue samples to detect FRL1 expression and analyze its prognostic value. Colony formation, the CCK-8 assay, flow cytometry, and in vivo nude mice subcutaneous experiments were used to identify the effects of FRL1 on growth and proliferation. In vitro tests for wound healing, migration, and invasion were used to assess the involvement of FRL1 in invasion and metastatic potential. The process of epithelial-mesenchymal transition process (EMT) and the MMP2 expression were detected in stably transfected RCC cells via western blotting, as well as in tumor tissue paraffin sections from xenograft model.

RESULTS

Both FRL1 mRNA and protein levels were noticeably elevated in ccRCC cell lines and samples. Aberrant overexpression of FRL1 was associated with unfavorable clinicopathological features of ccRCC and indicated poor prognosis. Ectopic overexpression of FRL1 increased the growth-promoting traits of ccRCC cells as well as the migratory and invasive capacity of RCC cells, whereas FRL1-silencing caused the opposite results. In addition, FRL1 promoted epithelial-mesenchymal transition (EMT) and upregulated the expression of matrix metalloproteinase 2 (MMP2). Finally, overexpression of FRL1 upregulated phosphorylation level of ERK1/2 with no effect on total level of ERK1/2 in the RCC cells. MAPK/ERK inhibitor reversed the promotional effects of FRL1.

CONCLUSION

FRL1 was overexpressed in ccRCC tissues and predicted poor prognosis. FRL1 contributes to invasion and aggressive phenotype of ccRCC by facilitating EMT through MAPK/MMP2 axis.

Long-chain perfluoroalkyl carboxylates induce cytoskeletal abnormalities and activate epithelial-mesenchymal transition in both renal cell carcinoma 3D cultures and Caki-1 xenografted mouse model

Exposure to perfluorooctanoate (PFOA; a type of perfluoroalkyl carboxylates [PFACs]) may be correlated with the incidence of kidney cancer in individuals exposed to high levels of PFOA. However, mechanistic studies on the influence of PFACs on renal cell carcinoma (RCC) development are lacking. We explored the effects of five types of PFACs on RCC using in vitro and in vivo models to fill this knowledge gap and provide information for environmental/usage regulations. Using 2D/3D cultures of Caki-1 cells, a human clear cell RCC line, we examined the effects of short-chain (SC) PFACs and long-chain (LC) PFACs on RCC physio/pathological markers, including the cytoskeleton, epithelial-mesenchymal transition (EMT)-related proteins, and Na+/K+-ATPase. We also administered three different PFACs orally to mice harboring Caki-1 xenografts to assess the impact of these compounds on engrafted RCC in vivo. Compared with the effects of SCPFACs, mice with Caki-1 xenografts treated with LCPFACs showed increased EMT-related protein expression and exhibited liver toxicity. Therefore, LCPFACs induced EMT, influencing cancer metastasis activity, and displayed higher toxicity in vivo compared with SCPFACs. These findings improve our understanding of the effects of PFACs on RCC development and their corresponding in vivo toxicity, which is crucial for regulating these substances to protect public health.

Hsa_circ_0057105 modulates a balance of epithelial-mesenchymal transition and ferroptosis vulnerability in renal cell carcinoma

BACKGROUND

The incidence of renal cell carcinoma (RCC) has increased in recent years. Metastatic RCC is common and remains a major cause of mortality. A regulatory role for circular RNAs (circRNAs) in the occurrence and progression of RCC has been identified, but their function, molecular mechanisms, and potential clinical applications remain poorly understood.

METHODS

High-throughput RNA sequencing was used to explore the differential expression of circRNAs and their related pathways in RCC patients. Transwell and CCK-8 assays were used to assess the function of hsa_circ_0057105 in RCC cells. The clinical relevance of hsa_circ_0057105 was evaluated in a cohort of RCC patients. The hsa_circ_0057105 regulatory axis was defined using RNA pull-down, luciferase reporter assays, and fluorescence in situ hybridization assays, and the in vivo effect of hsa_circ_0057105 was validated using animal experiments.

RESULTS

Single-sample gene set enrichment analysis and correlation analysis of RNA-seq data showed that hsa_circ_0057105 was potentially oncogenic and may serve to regulate epithelial-mesenchymal transition (EMT) activation in RCC. Hsa_circ_0057105 expression was associated with advanced TNM stages and was an independent prognostic factor for poor RCC patient survival. Phenotypic studies show that hsa_circ_0057105 can enhance the migration and invasion abilities of RCC cells. Further, hsa_circ_0057105 was shown to inhibit the expression of miR-577, a miRNA that regulated the expression of both COL1A1, which induced EMT activation, and VDAC2, which modulated ferroptosis sensitivity. The dual regulatory roles of hsa_circ_0057105 on EMT and ferroptosis sensitivity were verified using rescue experiments. Animal studies confirmed that hsa_circ_0057105 increased the metastatic ability and ferroptosis sensitivity of RCC cells in vivo.

CONCLUSIONS

In RCC, hsa_circ_0057105 regulates COL1A1 and VDAC2 expression through its sponge effect on miR-577, acting like a 'double-edged sword'. These findings provide new insight into the relationship between EMT and ferroptosis in RCC and provide potential biomarkers for RCC surveillance and treatment.

Free-Fatty Acid Receptor-4 (FFA4/GPR120) differentially regulates migration, invasion, proliferation and tumor growth of papillary renal cell carcinoma cells

Kidney cancer is among the 10 most common cancers, and renal cell carcinoma (RCC), which represent 90% of all kidney cancers, has the highest mortality rate of all genitourinary cancers. Papillary RCC (pRCC) is the second most frequent subtype of RCC and demonstrates distinct characteristics compared to other subtypes, including a high degree of metastasis and resistance to treatments against the more common clear cell RCC (ccRCC) subtype. Here, we demonstrate that the Free-Fatty Acid Receptor-4 (FFA4), a G protein-coupled receptor that is endogenously activated by medium-to-long chain free-fatty acids, is upregulated in pRCC compared to patient-matched normal kidney tissue, and that the expression of FFA4 increases with the degree of pathological grading of pRCC. Our data also show that FFA4 transcript is not expressed in ccRCC cell lines, but is expressed in the well-characterized metastatic pRCC cell line ACHN. Furthermore, we show that agonism of FFA4 with the selective agonist cpdA positively regulates ACHN cell migration and invasion in a manner dependent on PI3K/AKT/NF-κB signaling to COX-2 and MMP-9, with partial-dependence on EGFR transactivation. Our results also demonstrate that FFA4 agonism induces STAT-3-driven epithelial-mesenchymal transition, suggesting a significant role for FFA4 in pRCC metastasis. On the contrary, FFA4 agonism significantly reduces cell proliferation and tumor growth, suggesting that the receptor may have opposing effects on pRCC cell growth and migration. Together, our data demonstrate that FFA4 has significant functional roles in pRCC cells and may be an attractive target for study of pRCC and development of RCC pharmacotherapeutics.

Free-fatty acid receptor-1 (FFA1/GPR40) promotes papillary RCC proliferation and tumor growth via Src/PI3K/AKT/NF-κB but suppresses migration by inhibition of EGFR, ERK1/2, STAT3 and EMT

BACKGROUND

Papillary renal cell carcinoma (pRCC) is a highly metastatic genitourinary cancer and is generally irresponsive to common treatments used for the more prevalent clear-cell (ccRCC) subtype. The goal of this study was to examine the novel role of the free fatty-acid receptor-1 (FFA1/GPR40), a cell-surface expressed G protein-coupled receptor that is activated by medium-to-long chained dietary fats, in modulation of pRCC cell migration invasion, proliferation and tumor growth.

METHODS

We assessed the expression of FFA1 in human pRCC and ccRCC tumor tissues compared to patient-matched non-cancerous controls, as well as in RCC cell lines. Using the selective FFA1 agonist AS2034178 and the selective FFA1 antagonist GW1100, we examined the role of FFA1 in modulating cell migration, invasion, proliferation and tumor growth and assessed the FFA1-associated intracellular signaling mechanisms via immunoblotting.

RESULTS

We reveal for the first time that FFA1 is upregulated in pRCC tissue compared to patient-matched non-cancerous adjacent tissue and that its expression increases with pRCC cancer pathology, while the inverse is seen in ccRCC tissue. We also show that FFA1 is expressed in the pRCC cell line ACHN, but not in ccRCC cell lines, suggesting a unique role in pRCC pathology. Our results demonstrate that FFA1 agonism promotes tumor growth and cell proliferation via c-Src/PI3K/AKT/NF-κB and COX-2 signaling. At the same time, agonism of FFA1 strongly inhibits migration and invasion, which are mechanistically mediated via inhibition of EGFR, ERK1/2 and regulators of epithelial-mesenchymal transition.

CONCLUSIONS

Our data suggest that FFA1 plays oppositional growth and migratory roles in pRCC and identifies this receptor as a potential target for modulation of pathogenesis of this aggressive cancer.

Cellular and Molecular Players in the Tumor Microenvironment of Renal Cell Carcinoma

Globally, clear-cell renal cell carcinoma (ccRCC) represents the most prevalent type of kidney cancer. Surgery plays a key role in the treatment of this cancer, although one third of patients are diagnosed with metastatic ccRCC and about 25% of patients will develop a recurrence after nephrectomy with curative intent. Molecular-target-based agents, such as tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs), are recommended for advanced cancers. In addition to cancer cells, the tumor microenvironment (TME) includes non-malignant cell types embedded in an altered extracellular matrix (ECM). The evidence confirms that interactions among cancer cells and TME elements exist and are thought to play crucial roles in the development of cancer, making them promising therapeutic targets. In the TME, an unfavorable pH, waste product accumulation, and competition for nutrients between cancer and immune cells may be regarded as further possible mechanisms of immune escape. To enhance immunotherapies and reduce resistance, it is crucial first to understand how the immune cells work and interact with cancer and other cancer-associated cells in such a complex tumor microenvironment.

ApoM suppresses kidney renal clear cell carcinoma growth and metastasis via the Hippo-YAP signaling pathway

Renal cell carcinoma is one of the most common malignancies worldwide, and kidney renal clear cell carcinoma (KIRC) is the most common histopathological type of renal cell carcinoma. However, the mechanism of KIRC progression remains poorly understood. Apolipoprotein M (ApoM) is a plasma apolipoprotein and a member of the lipid transport protein superfamily. Lipid metabolism is essential for tumor progression, and its related proteins can be used as therapeutic targets for tumors. ApoM influences the development of several cancers, but its relationship with KIRC remains unclear. In this study, we aimed to investigate the biological function of ApoM in KIRC and to reveal its potential molecular mechanisms. We found that ApoM expression was significantly reduced in KIRC and was strongly correlated with patient prognosis. ApoM overexpression significantly inhibited KIRC cell proliferation in vitro, suppressed the epithelial mesenchymal transition (EMT) of KIRC cells, and decreased their metastatic capacity. Additionally, the growth of KIRC cells was inhibited by ApoM overexpression in vivo. In addition, we found that overexpression of ApoM in KIRC attenuated Hippo-YAP protein expression and YAP stability and thus inhibited KIRC growth and progression. Therefore, ApoM may be a potential target for the treatment of KIRC.

Correlation Between Tumor-Associated Collagen Signature and Fibroblast Activation Protein Expression With Prognosis of Clear Cell Renal Cell Carcinoma Patient

Background

Despite recent promising findings from immunotherapy and other targeted medicines, individuals with metastatic clear cell renal cell carcinoma (mCCRCC) still have a poor prognosis. Biomarkers associated with metastatic status in CCRCC are important for early detection and for the identification of new therapeutic targets. The expression of fibroblast activation protein (FAP) is associated with the development of early metastases and worse cancer-specific survival. Tumor-associated collagen signature (TACS) is a type of collagen that develops during tumor growth and is associated with tumor invasion.

Methods

Twenty-six mCCRCC patients that underwent nephrectomy were admitted to this study. Data regarding age, sex, Fuhrman's grade, tumor diameter, staging, FAP expression, and TACS grading were collected. Spearman rho test was used to correlate FAP expression and TACS grading in both primary tumors and metastases and with the patient's age and sex.

Results

FAP manifestation correlated positively with TACS degree (Spearman rho test r = 0.51; P = 0.0001). FAP was positive in 25 (96%) of all intratumor samples and positive in 22 (84%) of all stromal samples.

Conclusions

FAP can be used as a prognostic factor in mCCRCC; its presence can predict the aggressiveness of mCRCC and poorer outcome in the patient. Furthermore, TACS can also be used for the prediction of aggressiveness and metastasis due to the changes necessary for a tumor to invade other organs.

Proteoglycan SPOCK1 as a Poor Prognostic Marker Promotes Malignant Progression of Clear Cell Renal Cell Carcinoma via Triggering the Snail/Slug-MMP-2 Axis-Mediated Epithelial-to-Mesenchymal Transition

Sparc/osteonectin, cwcv, and kazal-like domains proteoglycan 1 (SPOCK1) has been reported to play an oncogenic role in certain cancer types; however, the role of SPOCK1 in the progression of clear cell renal cell carcinoma (ccRCC) remains elusive. Here, higher SPOCK1 transcript and protein levels were observed in ccRCC tissues compared to normal tissues and correlated with advanced clinical stages, larger tumor sizes, and lymph node and distal metastases. Knockdown and overexpression of SPOCK1 in ccRCC cells led to decreased and increased cell clonogenic and migratory/invasive abilities in vitro as well as lower and higher tumor growth and invasion in vivo, respectively. Mechanistically, the gene set enrichment analysis (GSEA) database was used to identify the gene set of epithelial-to-mesenchymal transition (EMT) pathways enriched in ccRCC samples with high SPOCK1 expression. Further mechanistic investigations revealed that SPOCK1 triggered the Snail/Slug-matrix metalloproteinase (MMP)-2 axis to promote EMT and cell motility. Clinical ccRCC samples revealed SPOCK1 to be an independent prognostic factor for overall survival (OS), and positive correlations of SPOCK1 with MMP-2 and mesenchymal-related gene expression levels were found. We observed that patients with SPOCK1^high/MMP2^high tumors had the shortest OS times compared to others. In conclusion, our findings reveal that SPOCK1 can serve as a useful biomarker for predicting ccRCC progression and prognosis, and as a promising target for treating ccRCC.

WY-14643 attenuates lipid deposition via activation of the PPARα/CPT1A axis by targeting Gly335 to inhibit cell proliferation and migration in ccRCC

Background

Histologically, cytoplasmic deposits of lipids and glycogen are common in clear cell renal cell carcinoma (ccRCC). Owing to the significance of lipid deposition in ccRCC, numerous trials targeting lipid metabolism have shown certain therapeutic potential. The agonism of peroxisome proliferator-activated receptor-α (PPARα) via ligands, including WY-14,643, has been considered a promising intervention for cancers.

Methods

First, the effects of WY-14,643 on malignant behaviors were investigated in ccRCC in vitro. After RNA sequencing, the changes in lipid metabolism, especially neutral lipids and glycerol, were further evaluated. Finally, the underlying mechanisms were revealed.

Results

Phenotypically, the proliferation and migration of ccRCC cells treated with WY-14,643 were significantly inhibited in vitro. A theoretical functional mechanism was proposed in ccRCC: WY-14,643 mediates lipid consumption by recognizing carnitine palmitoyltransferase 1 A (CPT1A). Activation of PPARα using WY-14,643 reduces lipid deposition by increasing the CPT1A level, which also suppresses the NF-κB signaling pathway. Spatially, WY-14,643 binds and activates PPARα by targeting Gly335.

Conclusion

Overall, WY-14,643 suppresses the biological behaviors of ccRCC in terms of cell proliferation, migration, and cell cycle arrest. Furthermore, its anticancer properties are mediated by the inhibition of lipid accumulation, at least in part, through the PPARα/CPT1A axis by targeting Gly335, as part of the process, NF-κB signaling is also suppressed. Pharmacological activation of PPARα might offer a new treatment option for ccRCC.

Downregulation of Crystallin Lambda 1 is a New Independent Prognostic Marker in Clear Cell Renal Cell Carcinoma

Background

Clear cell renal cell carcinoma (ccRCC), the most prevalent kidney cancer subtype, has a high mortality rate. Crystallin lambda 1 (CRYL1) encodes an enzyme that catalyzes the dehydrogenation of L-gulonate into dehydro-L-gulonate in uronate cycle. CRYL1 dysregulation has been linked to the progression of several cancers. This research aimed to evaluate the prognostic significance of CRYL1 expression in ccRCC prognosis.

Methods

Clinical data and gene expression profiles on ccRCC were retrieved from the University of California Santa Cruz Xena platform. Differences (variations) in the expression profiles of CRYL1 in ccRCC and healthy tissues were found using RNA-sequencing data, and these findings were validated using qPCR with real-world samples. CRYL1 expression levels were also linked to clinicopathological characteristics, survival, and immune microenvironments. The potential pathway via which CRYL1 expression levels impact the prognosis of patients with ccRCC was investigated using gene set enrichment analysis (GSEA).

Results

In ccRCC tissues, CRYL1 expression levels were lower compared to healthy renal tissues in TCGA cohort (n = 535, P < 0.001), which was validated in another real-world cohort (n = 14, P < 0.001). Lower CRYL1 expression levels were linked to unfavorable clinicopathological characteristics and prognoses (P < 0.001). According to multivariate Cox regression analysis (P < 0.001), CRYL1 expression levels in patients with ccRCC could serve as an independent prognostic indicator. Furthermore, a strong link between CRYL1 expression levels and immune microenvironment was observed (P < 0.001). Finally, GSEA revealed that CRYL1 expression levels (P < 0.001) were associated with fatty acid metabolism, G2M checkpoint delays, and epithelial-mesenchymal transitions in ccRCC.

Conclusion

Our study found that lower levels of CRYL1 expression were linked to unfavorable clinicopathological characteristics and worse prognoses, and CRYL1 could serve as a new target for the treatment of ccRCC, which is useful for personalized medicine.

Isolation and Genomic Analysis of Single Circulating Tumor Cell Using Human Telomerase Reverse Transcriptase and Desmoglein-2

As epithelial cells in the circulation are considered to originate from the tumor, the epithelial cell adhesion molecule has been commonly used as a standard marker for circulating tumor cells (CTCs) isolation. However, it seems to disappear after the epithelial-mesenchymal transition that most cancer cells undergo for intravasation. Thus, more advanced techniques for CTC detection are needed to better understand the clinical significance of CTCs. A cancer cell-specifically-infecting or replicating virus that codes a fluorescent monitor gene can be a solution to efficiently detect CTCs. Thus, the authors designed an adenovirus to bind to desmoglein-2, which is highly expressed in most cancer cells. A cancer-specific human telomerase reverse transcriptase promoter is inserted to control a viral E1 region. The adenovirus is utilized to compare the number of CTCs from renal cell carcinoma and prostate cancer patients before and after surgery. The isolated two or three CTCs are eligible for whole genome sequencing. The genomic analysis proves the difference of variants between primary tumors and CTCs. Taken together, it is a fast and exact serial method for CTC isolation and the enriched genome sequencing may be used to determine the prognosis and as a point-of-care system for patients with cancer.

Molecular Characterization of Clear Cell Renal Cell Carcinoma Reveals Prognostic Significance of Epithelial-mesenchymal Transition Gene Expression Signature

BACKGROUND

There is an ongoing need to develop prognostic biomarkers to improve the management of clear cell renal cell carcinoma (ccRCC).

OBJECTIVE

To leverage enriched pathways in ccRCC to improve risk-stratification.

DESIGN, SETTING, AND PARTICIPANTS

We retrospectively identified two complementary discovery cohorts of patients with ccRCC who underwent (1) radical nephrectomy (RNx) with inferior vena cava tumor thrombectomy (patients = 5, samples = 24) and (2) RNx for localized disease and developed recurrence versus no recurrence (n = 36). Patients with localized ccRCC (M0) in The Cancer Genome Atlas (TCGA, n = 386) were used for validation.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

A differential expression gene (DEG) analysis was performed on targeted RNA next-generation sequencing data from both discovery cohorts. Using TCGA for validation, Kaplan-Meier survival analysis and multivariable Cox proportional hazard testing were utilized to investigate the prognostic impact of DEGs, cell cycle proliferation (CCP), and a novel epithelial-mesenchymal transition (EMT) score on progression-free (PFS) and disease-specific (DSS) survival.

RESULTS AND LIMITATIONS

In the discovery cohorts, we observed overexpression of WT1 and CCP genes in the tumor thrombus versus the primary tumor, as well as in patients with recurrence versus those without recurrence. A hallmark pathway analysis demonstrated enrichment of the EMT- and CCP-related pathways in patients with high WT1 expression in the TCGA (validation) ccRCC cohort. CCP and EMT scores were derived in the validation cohort, which was stratified into four risk groups using Youden Index cut points: CCP^low/EMT^low, CCP^low/EMT^high, CCP^high/EMT^low, and CCP^high/EMT^high. The CCP^high/EMT^high risk group was associated with the worst PFS and DSS (both p < 0.001). In a multivariable analysis, CCP^high/EMT^high was independently associated with poor PFS and DSS (hazard ratio = 4.6 and 10.3, respectively; p < 0.001).

CONCLUSIONS

We demonstrate the synergistic prognostic impact of EMT in tumors with a high CCP score. Our novel EMT score has the potential to improve risk stratification and provide potential novel therapeutic targets.

PATIENT SUMMARY

Genes involved in epithelial-mesenchymal transition provides important prognostic information for patients with clear cell renal cell carcinoma.

LncRNAs in the Regulation of Genes and Signaling Pathways through miRNA-Mediated and Other Mechanisms in Clear Cell Renal Cell Carcinoma

The fundamental novelty in the pathogenesis of renal cell carcinoma (RCC) was discovered as a result of the recent identification of the role of long non-coding RNAs (lncRNAs). Here, we discuss several mechanisms for the dysregulation of the expression of protein-coding genes initiated by lncRNAs in the most common and aggressive type of kidney cancer-clear cell RCC (ccRCC). A model of competitive endogenous RNA (ceRNA) is considered, in which lncRNA acts on genes through the lncRNA/miRNA/mRNA axis. For the most studied oncogenic lncRNAs, such as HOTAIR, MALAT1, and TUG1, several regulatory axes were identified in ccRCC, demonstrating a number of sites for various miRNAs. Interestingly, the LINC00973/miR-7109/Siglec-15 axis represents a novel agent that can suppress the immune response in patients with ccRCC, serving as a valuable target in addition to the PD1/PD-L1 pathway. Other mechanisms of action of lncRNAs in ccRCC, involving direct binding with proteins, mRNAs, and genes/DNA, are also considered. Our review briefly highlights methods by which various mechanisms of action of lncRNAs were verified. We pay special attention to protein targets and signaling pathways with which lncRNAs are associated in ccRCC. Thus, these new data on the different mechanisms of lncRNA functioning provide a novel basis for understanding the pathogenesis of ccRCC and the identification of new prognostic markers and targets for therapy.

Circular RNAs and their role in renal cell carcinoma: a current perspective

Circular RNAs (circRNAs) are a new class of long non-coding RNAs, that results from a special type of alternative splicing referred to as back-splicing. They are widely distributed in eukaryotic cells and demonstrate tissue-specific expression patterns in humans. CircRNAs actively participate in various important biological activities like gene transcription, pre-mRNA splicing, translation, sponging miRNA and proteins, etc. With such diverse biological functions, circRNAs not only play a crucial role in normal human physiology, as well as in multiple diseases, including cancer. In this review, we summarized our current understanding of circRNAs and their role in renal cell carcinoma (RCC), the most common cancer of kidneys. Studies have shown that the expression level of several circRNAs are considerably varied in RCC samples and RCC cell lines suggesting the potential role of these circRNAs in RCC progression. Several circRNAs promote RCC development and progression mostly via the miRNA/target gene axis making them ideal candidates for novel anti-cancer therapy. Apart from these, there are a few circRNAs that are significantly downregulated in RCC and overexpression of these circRNAs leads to suppression of RCC growth. Differential expression patterns and novel functions of circRNAs in RCC suggest that circRNAs can be utilized as potential biomarkers and therapeutic targets for RCC therapy. However, our current understanding of the role of circRNA in RCC is still in its infancy and much comprehensive research is needed to achieve clinical translation of circRNAs as biomarkers and therapeutic targets in developing effective treatment options for RCC.

Transgelin Contributes to a Poor Response of Metastatic Renal Cell Carcinoma to Sunitinib Treatment

Renal cell carcinoma (RCC) represents about 2-3% of all cancers with over 400,000 new cases per year. Sunitinib, a vascular endothelial growth factor tyrosine kinase receptor inhibitor, has been used mainly for first-line treatment of metastatic clear-cell RCC with good or intermediate prognosis. However, about one-third of metastatic RCC patients do not respond to sunitinib, leading to disease progression. Here, we aim to find and characterize proteins associated with poor sunitinib response in a pilot proteomics study. Sixteen RCC tumors from patients responding (8) vs. non-responding (8) to sunitinib 3 months after treatment initiation were analyzed using data-independent acquisition mass spectrometry, together with their adjacent non-cancerous tissues. Proteomics analysis quantified 1996 protein groups (FDR = 0.01) and revealed 27 proteins deregulated between tumors non-responding vs. responding to sunitinib, representing a pattern of deregulated proteins potentially contributing to sunitinib resistance. Gene set enrichment analysis showed an up-regulation of epithelial-to-mesenchymal transition with transgelin as one of the most significantly abundant proteins. Transgelin expression was silenced by CRISPR/Cas9 and RNA interference, and the cells with reduced transgelin level exhibited significantly slower proliferation. Our data indicate that transgelin is an essential protein supporting RCC cell proliferation, which could contribute to intrinsic sunitinib resistance.

Antitumor effects of the multi-target tyrosine kinase inhibitor cabozantinib: a comprehensive review of the preclinical evidence

INTRODUCTION

Altered receptor tyrosine kinase (RTK) signaling contributes to tumorigenesis and suppression of immune-mediated destruction of cancer cells. Cabozantinib is an oral tyrosine kinase inhibitor that inhibits several RTKs involved in tumorigenesis, and is approved for the treatment of patients with progressive metastatic medullary thyroid cancer, advanced renal cell carcinoma, and hepatocellular carcinoma that has been previously treated with sorafenib.

AREAS COVERED

We present an up-to-date evaluation of preclinical evidence for RTK inhibition with cabozantinib, specifically VEGFR, MET, KIT, RET, AXL, FLT3, and associated antitumor effects. Preclinical investigations of cabozantinib in combination with other anticancer drugs are also reviewed.

EXPERT OPINION

Preclinical evidence shows that cabozantinib has antitumor activity against various cancer cells and exhibits synergy with other anticancer agents, including immune checkpoint inhibitors and hormone receptor or metabolic pathway inhibitors. Further optimization of cabozantinib treatment requires the identification of biomarkers of response and resistance, and exploration of complementary drug targets. Investigation of mechanisms of adaptive resistance, such as epithelial to mesenchymal transition (cancer intrinsic) and immunomodulation by the tumor microenvironment (cancer extrinsic), as well as identification of novel drug targets based on characterization of cancer stem cell metabolomic phenotypes, appear to be promising approaches.

Cabozantinib in Pretreated Patients with Metastatic Renal Cell Carcinoma with Sarcomatoid Differentiation: A Real-World Study

BACKGROUND

Renal cell carcinoma with sarcomatoid differentiation is a highly aggressive form of kidney cancer.

OBJECTIVE

We aimed to analyze the outcomes of patients treated with cabozantinib for metastatic renal cell carcinoma with sarcomatoid features.

METHODS

We retrospectively collected data from 16 worldwide centers. Overall survival and progression-free survival were analyzed using Kaplan-Meier curves. Cox proportional models were used for univariate and multivariate analyses.

RESULTS

We collected data from 66 patients with metastatic sarcomatoid renal cell carcinoma receiving cabozantinib as second-line (51%) or third-line (49%) therapy. The median progression-free survival from the start of cabozantinib was 7.59 months (95% confidence interval [CI] 5.75-17.49) and was longer in male patients (8.81 vs 5.95 months, p = 0.042) and in patients without bone metastases (7.59 vs 5.11 months, p = 0.010); the median overall survival was 9.11 months (95% CI 7.13-23.80). At the multivariate analysis, female sex (hazard ratio = 1.81; 95% CI 1.02-3.37, p = 0.046), bone metastases (hazard ratio = 2.62; 95% CI 1.34-5.10, p = 0.005), and International Metastatic Renal Cell Carcinoma Database Consortium criteria (hazard ratio = 3.04; 95% CI 1.54-5.99, p = 0.001) were significant predictors of worse overall survival.

CONCLUSIONS

Our data show that cabozantinib is active in pretreated patients with sarcomatoid renal cell carcinoma. Biomarkers are needed in this field to select patients for multi-kinase inhibitors or other options.

Ginsenoside compound K exerts antitumour effects in renal cell carcinoma via regulation of ROS and lncRNA THOR

Renal cell carcinoma (RCC) is a common type of kidney cancer that lacks effective therapeutic options. Ginsenoside compound K (CK), an active metabolite of ginsenosides, has been reported to induce apoptosis in various types of cancer cells. However, the effects of CK in RCC remain to be elucidated. Thus, the aim of the present study was to investigate the antitumor effects of CK on RCC cells. The effects of CK on the proliferation, migration, invasion, cell cycle and apoptosis of RCC cell lines (Caki-1 and 768-O) were investigated using MTT, wound healing, Transwell and flow cytometry assays, respectively. Changes in the expression levels of long non-coding RNAs (lncRNAs) and proteins were measured via reverse transcription-quantitative PCR and western blotting, respectively. Transfections with testis associated oncogenic (THOR) small interfering RNA and pcDNA were performed to knock down and overexpress lncRNA THOR, respectively. It was found that CK could effectively inhibit the proliferation, migration and invasion of RCC cells. CK also induced cell cycle arrest and caspase-dependent apoptosis in RCC cells. Furthermore, the generation of reactive oxygen species and inhibition of the lncRNA THOR played important roles in the antitumour effects of CK in RCC cells. The present data revealed that CK was a potent antitumour agent against RCC.

Synergistic Effects of TW-37 and ABT-263 on Renal Cell Carcinoma Cells

Background

Renal cell carcinoma (RCC) is a common urological system malignancy lack of effective therapeutic options. Upregulation of the Bcl-2 proteins was correlated with poor prognosis of RCC, suggesting that BH-3 mimetics may be a promising treatment option. ABT-263 is a BH3 mimetic that possesses anti-tumor effects. TW-37 is another inhibitor of Bcl-2 family protein with potential anti-tumor activities. However, since their effect as single agent is limited, combination treatment represents a strategy to improve the efficiency. We studied the ABT-263 in combination with TW-37 and analyzed the molecular mechanisms of action in RCC cells.

Methods

MTT and colony formation assays were used to measure the proliferation of RCC cells. Transwell assay was used to assay the migration and invasion of RCC cells. Cell cycle distribution and apoptosis were measured using the flow cytometry and apoptotic nucleosome assay, respectively. Western blotting was performed to measure the change of proteins. The anti-tumor effects of ABT-263, TW-37 and their combination were also evaluated in vivo.

Results

Cotreatment of TW-37 and ABT-263 synergistically repressed the proliferation of RCC cells. TW-37 and ABT-263 also synergistically inhibited the migration and invasion of RCC cells It was also showed that TW-37 and ABT-263 synergistically induced cell cycle arrest at the G2/M phase. Furthermore, increased apoptosis was observed after exposure to TW-37 and ABT-263. Mechanism investigation showed that TW-37 and ABT-263 synergistically induced apoptosis via the mitochondrial pathway and relied on the activation of Bax and caspases. Furthermore, ERK signaling pathway activation was detected after treated with TW-37 and ABT-263. Finally, TW-37 and ABT-263 also synergistically repressed the growth of RCC cells in xenograft mice.

Conclusion

In summary, our data demonstrated that combined treatment with TW-37 and ABT-263 exhibited synergistic RCC cell death and this combination may be applied as an effective therapeutic strategy against RCC.

Upregulation of TMEM45A Promoted the Progression of Clear Cell Renal Cell Carcinoma in vitro

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is the most common and aggressive type of primary kidney cancer worldwide. Transmembrane protein 45A (TMEM45A) has been reported to be closely associated with the progression of several cancers. However, the role of TMEM45A in ccRCC remains unclear. Our study intended to explore the potential role of TMEM45A in ccRCC.

METHODS

Data on the expression of TMEM45A were obtained from multiple databases, including UCSC, GEPIA2, Oncomine and TIMER. Real-world samples of ccRCC and paired normal renal tissues were used to confirm the information obtained from the databases. In addition, the prognostic value of TMEM45A was evaluated. Loss-of-function assays were performed using TMEM45A-targeting lentivirus to evaluate the biological role of TMEM45A in renal cancer cells. Gene set enrichment analysis (GSEA) was performed to investigate the potential molecular mechanisms.

RESULTS

TMEM45A was significantly overexpressed in patients with ccRCC and correlated with poor overall survival and disease-free survival. In addition, the expression of TMEM45A was closely associated with various clinicopathological parameters such as histological grade and TNM stage. Knockdown of TMEM45A inhibited the proliferation and migration and promoted the apoptosis of ccRCC cells in vitro. The results of the GSEA suggested that TMEM45A was potentially involved in the promotion of epithelial-mesenchymal transition (EMT) and inflammatory response in ccRCC.

CONCLUSION

TMEM45A was overexpressed and associated with poor survival and acted as a tumour promoter in ccRCC; therefore, might be a potential prognostic marker and therapeutic target.

Expression of apolipoprotein C1 in clear cell renal cell carcinoma: An oncogenic gene and a prognostic marker

This study aimed to explore whether APOC1 expression has a function in the biological behavior of clear cell renal cell carcinoma (ccRCC) cells and its possible mechanism. Bioinformatics analysis of data TCGA and OnComine was conducted to explore the expression pattern and prognostic value of APOC1, as well as the relationship between APOC1 expression and clinical indicators. Loss- and gain- of APOC1 function assays were carried out to assess the biological functions of APOC1. Western blotting was applied to detect protein expression. We revealed that APOC1 was upregulated in ccRCC tissues. APOC1 expression was related to gender, grade, pathologic-T, pathologic-stage, and pathologic-M in patients with ccRCC. Meanwhile, Kaplan-Meier analysis evidenced that the high APOC1 expression indicated unfavorable outcomes of ccRCC. Functional experiments in vitro revealed that upregulation of APOC1 in UT33A cells promoted cell proliferation, invasion, and migration, while downregulation of APOC1 in 786-O cells had the opposite effect. Furthermore, epithelial mesenchymal transition (EMT) was activated in cells with upregulated APOC1 but inhibited in cells with down-regulated APOC1. Collectively, our data suggested that APOC1 was overexpressed in ccRCC cells and promoted the malignant biological behaviors and EMT of ccRCC cells.

GLIPR2 is a negative regulator of autophagy and the BECN1-ATG14-containing phosphatidylinositol 3-kinase complex

A key mediator of macroautophagy/autophagy induction is the class III phosphatidylinositol 3-kinase complex I (PtdIns3K-C1) consisting of PIK3C3/VPS34, PIK3R4/VPS15, BECN1, and ATG14. Although several proteins are known to enhance or decrease PtdIns3K-C1 activity, our understanding of the molecular regulation of PtdIns3K-C1 is still incomplete. Previously, we identified a Golgi-associated protein, GLIPR2, in a screen for proteins that interact with amino acids 267–284 of BECN1, a region of BECN1 sufficient to induce autophagy when fused to a cell penetrating leader sequence. In this study, we used CRISPR-Cas9-mediated depletion of GLIPR2 in cells and mice to investigate the role of GLIPR2 in the regulation of autophagy and PtdIns3K-C1 activity. Depletion of GLIPR2 in HeLa cells increased autelophagic flux and generation of phosphatidylinositol 3-phosphate (PtdIns3P). GLIPR2 knockout resulted in less compact Golgi structures, which was also observed in autophagy-inducing conditions such as amino acid starvation or Tat-BECN1 peptide treatment. Importantly, the binding of GLIPR2 to purified PtdIns3K-C1 inhibited the in vitro lipid kinase activity of PtdIns3K-C1. Moreover, the tissues of glipr2 knockout mice had increased basal autophagic flux as well as increased recruitment of the PtdIns3P-binding protein, WIPI2. Taken together, our findings demonstrate that GLIPR2 is a negative regulator of PtdIns3K-C1 activity and basal autophagy.

Abbreviations: ATG14: autophagy related 14; Baf A1: bafilomycin A₁; BARA: β-α repeated, autophagy-specific; CQ: chloroquine; GFP: green fluorescent protein; GLIPR2: GLI pathogenesis related 2; HBSS: Hanks’ balanced salt solution; KO: knockout; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; PBS: phosphate-buffered saline; PtdIns3K-C1: phosphatidylinositol 3-kinase complex I; PtdIns3P: phosphatidylinositol-3-phosphate; SEM: standard error of the mean; WIPI2: WD repeat domain, phosphoinositide interacting 2

Role of the KEAP1-NRF2 Axis in Renal Cell Carcinoma

NRF2 is a transcription factor that coordinates the antioxidant response in many different tissues, ensuring cytoprotection from endogenous and exogenous stress stimuli. In the kidney, its function is essential in appropriate cellular response to oxidative stress, however its aberrant activation supports progression, metastasis, and resistance to therapies in renal cell carcinoma, similarly to what happens in other nonrenal cancers. While at the moment direct inhibitors of NRF2 are not available, understanding the molecular mechanisms that regulate its hyperactivation in specific tumor types is crucial as it may open new therapeutic perspectives. Here, we focus our attention on renal cell carcinoma, describing how NRF2 hyperactivation can contribute to tumor progression and chemoresistance. Furthermore, we highlight the mechanism whereby the many pathways that are generally altered in these tumors converge to dysregulation of the KEAP1-NRF2 axis.

Curcumin Negatively Regulates Cigarette Smoke-Induced Renal Cell Carcinoma Epithelial-Mesenchymal Transition Through the ERK5/AP-1 Pathway

Background

So far, little research has been conducted regarding the underlying mechanism of renal carcinogenesis at molecular level. Epithelial–mesenchymal transition (EMT) exerts an important part during tumor genesis as well as the development through mitogen-activated protein kinase (MAPK) pathways. Therefore, we hypothesized that EMT could promote renal cell carcinoma (RCC) progression via the ERK5/AP-1pathway.

Materials and Methods

The RCC cell lines were utilized to be the models with in vitro exposure to cigarette smoke extract (CSE). We used the curcumin for the EMT intervention study. In the present study, immunohistochemistry (IHC), Western blotting, and real-time quantitative reverse transcription PCR had been used to determine the experimental results. EMT phenotypic alterations were assessed by changes in cell morphology, invasion and transfer ability, as well as expression of epithelial and mesenchymal markers.

Results

In human renal cell carcinoma tissue, E-cadherin expression within the smoking renal cancer patients was down-regulated compared with that among the non-smokers. However, Vimentin, N-cadherin, and TWIST levels increased (P<0.05). Significantly, we clarified that ERK5/AP-1 exerted positive regulation on the renal cell carcinoma EMT mediated by CS, which was suggested based on the results of CS activating the ERK5/AP-1 pathway, as well as ERK5 inhibition via XMD8-92 reversed AP-1 protein levels and the EMT process. Furthermore, curcumin showed the same inhibitory effect as XMD8-92 and significantly reversed CS-induced EMT through inhibiting the ERK5/AP-1 signaling pathway.

Conclusion

The above results indicated that ERK5/AP-1 signaling pathway exerts a vital part for CS-associated RCC development and cancer intervention.

Practicability of clinical application of bladder cancer molecular classification and additional value of epithelial-to-mesenchymal transition: prognostic value of vimentin expression

BACKGROUND

Bladder cancer (BlCa) taxonomy has proved its impact in patient outcome and selection for targeted therapies, but such transcriptomic-based classification has not yet translated to routine practice. Moreover, epithelial-to-mesenchymal transition (EMT) has shown relevance in acquisition of more aggressive BlCa phenotype. We aimed to test the usefulness of the molecular classification, as defined by immunohistochemistry (a routinely performed and easy-to-implement technique), in a well-defined BlCa cohort of both non-muscle invasive (NMIBC) and muscle invasive (MIBC) disease. Also, we aimed to assess the additional prognostic value of the mesenchymal marker vimentin to the stratification strategy.

METHODS

A total of 186 samples were available. Immunohistochemistry/RT-qPCR for luminal markers GATA3/FOXA1, basal markers KRT5/KRT6A and vimentin were performed.

RESULTS

mRNA expression levels of the markers positively correlated with immunoexpression scores. We found substantial overlapping in immunoexpression of luminal and basal markers, evidencing tumor heterogeneity. In MIBC, basal tumors developed recurrence more frequently. NMIBC patients with higher vimentin immunoexpression endured poorer disease-free survival, and increased expression was observed from normal bladder-NMIBC-MIBC-metastases.

CONCLUSIONS

The classification has the potential to be implemented in routine, but further adjustments in practical scoring should be defined; focusing on additional markers, including those related to EMT, may further refine BlCa molecular taxonomy.

Serum response factor increases renal cell carcinoma migration and invasion through promoting epithelial-mesenchymal transition

OBJECTIVE

To explore the regulation and function of serum response factor in epithelial-mesenchymal transition in renal cell carcinoma.

METHODS

First, bioinformatics analysis of human renal cell carcinoma tissues was carried out. Then, the expression of serum response factor, mesenchymal markers (N-cadherin, vimentin and fibronectin) and epithelial markers (zonula occludens-1 and epithelial cadherin) was examined in 786-O cells (a human renal cell carcinoma cell line). Serum response factor was overexpressed with pcDNA-serum response factor plasmid, and suppressed by CCG-1423 (a small molecule inhibitor of serum response factor) to study how serum response factor affects epithelial-mesenchymal transition in renal cell carcinoma. A xenograft nude mouse model was established to explore whether serum response factor affected the tumorigenic ability of renal cell carcinoma cells.

RESULTS

Serum response factor interacted with several important differentially expressed genes in renal cell carcinoma. In 786-O cells, serum response factor, N-cadherin, vimentin and fibronectin were upregulated, whereas zonula occludens-1 and epithelial cadherin were downregulated. Serum response factor upregulation in 786-O cells increased the Snail expression. Serum response factor suppression reduced Snail induction, and migration and invasion in renal cell carcinoma, which decreased the xenograft tumor volume.

CONCLUSIONS

Serum response factor is a critical transcription factor in human renal cell carcinoma. Increased serum response factor activity induces epithelial-mesenchymal transition, migration and invasion in 786-O cells, and facilitates the progression of renal cell carcinoma. Targeting serum response factor with CCG-1423 might be an attractive therapeutic strategy for renal cell carcinoma.

Prognostic significance of proteomics and multi-omics studies in renal carcinoma

INTRODUCTION

Renal carcinoma, and in particular its most common variant, the clear cell subtype, is often diagnosed incidentally through abdominal imaging and frequently, the tumor is discovered at an early stage. However, 20% to 40% of patients undergoing nephrectomy for clinically localized renal cancer, even after accurate histological and clinical classification, will develop metastasis or recurrence, justifying the associated mortality rate. Therefore, even if renal carcinoma is not among the most frequent nor deadly cancers, a better prognostication is needed.

AREAS COVERED

Recently proteomics or other omics combinations have been applied to both cancer tissues, on the neoplasia itself and surrounding microenvironment, cultured cells, and biological fluids (so-called liquid biopsy) generating a list of prognostic molecular tools that will be reviewed in the present paper.

EXPERT OPINION

Although promising, none of the approaches listed above has been yet translated in clinics. This is likely due to the peculiar genetic and phenotypic heterogeneity of this cancer, which makes nearly each tumor different from all the others. Attempts to overcome this issue will be also revised. In particular, we will discuss how the application of omics-integrated approaches could provide the determinants of response to the different targeted drugs.

Inhibition of BRD4 prevents proliferation and epithelial-mesenchymal transition in renal cell carcinoma via NLRP3 inflammasome-induced pyroptosis

BRD4 has long been implicated in many different pathological processes, in particular, the development of cancer and inflammation. Pyroptosis is a newly recognized type of inflammatory programmed cell death. However, the correlation between BRD4 and pyroptosis in renal cell carcinoma (RCC) remains elusive. The present study demonstrates that BRD4 expression levels are markedly upregulated, while pyroptosis-associated proteins are significantly reduced, in RCC tissues and cells. Inhibition of BRD4, via either genetic knockdown or use of bromodomain inhibitor JQ1, prevented cell proliferation and epithelial-mesenchymal transition (EMT) progression and induced caspase-1-dependent pyroptosis in RCC both in vitro and in vivo. In addition, BRD4 inhibition suppressed proliferation and EMT though pyroptosis in vitro and in vivo. Moreover, NLRP3, which mediates caspase-1-dependent pyroptosis, was increased upon BRD4 inhibition. Furthermore, the transcriptional activity of NLRP3 was enhanced by BRD4 inhibition, and this enhancement was blocked by activation of NF-κB phosphorylation, indicating that NF-κB is an upstream regulator of NLRP3. Collectively, these results show that BRD4 inhibition prevents cell proliferation and EMT, and exerts an antitumor effect in RCC by activating the NF-κB-NLRP3-caspase-1 pyroptosis signaling pathway. Thus, BRD4 is a potential target for RCC treatment, and JQ1 shows promise as a therapeutic agent for this disease.

TNFAIP8 promotes the migration of clear cell renal cell carcinoma by regulating the EMT

Background: Clear cell renal cell carcinoma (ccRCC) is characterized by high metastatic potential, and the epithelial-mesenchymal transition (EMT) has been shown to play a key role in multiple cancer progression, migration and metastasis and is the leading cause of poor prognosis. Currently, tumor necrosis factor-α-induced protein 8 (TNFAIP8/TIPE) is a newly discovered tumorigenesis factor, and TNFAIP8 and the EMT influence the migration of renal cancer cells.

Methods: In this study, we first analyzed the relationship between TNFAIP8 and ccRCC using bioinformatics, followed by immunohistochemistry to evaluate the relationship between the two in clinical samples. Subsequently, reverse transcription PCR and western blotting confirmed the expression of TNFAIP8 in ccRCC cells. Furthermore, we measured the migration and invasion abilities by using wound healing and transwell assays after overexpression or knockdown of TNFAIP8 in cells. In addition, we verified whether TNFAIP8 affects the EMT process in ccRCC by quantitative real-time PCR, western blotting, immunohistochemistry and immunofluorescence experiments.

Results: Through database analysis, we found that TNFAIP8 was highly expressed in ccRCC patients and was positively correlated with tumor stage and grade, indicating that TNFAIP8 is associated with the development of advanced ccRCC and poor prognosis. We subsequently confirmed that TNFAIP8 was abnormally overexpressed in clinical samples and ccRCC cell lines and that TNFAIP8 promoted ccRCC cell migration and invasion in vitro. Finally, we found that TNFAIP8 regulated EMT-related molecule expression and regulated the EMT process.

Conclusion: High expression of TNFAIP8 reinforces migration and regulates the EMT in ccRCC, conferring the metastatic potential of ccRCC and suggesting that TNFAIP8 may be a potential therapeutic target for the treatment of advanced ccRCC.

Silibinin inhibits epithelial‑mesenchymal transition of renal cell carcinoma through autophagy‑dependent Wnt/β‑catenin signaling

Silibinin is a flavonoid extracted from milk thistle seeds which has been widely used as a hepatoprotective and antioxidant agent. Recently, accumulating evidence has demonstrated the anti-cancer effects of silibinin in various cancer models. It was previously reported that silibinin induced apoptosis and decreased metastasis by activating autophagy in renal cell carcinoma (RCC). However, the underlying molecular mechanisms by which silibinin regulates autophagy remain largely unknown. The aim of the present study was to investigate the effects of silibinin on RCC metastasis in vitro and in vivo, with a focus on autophagy-dependent Wnt/β-catenin signaling. Human RCC 786-O and ACHN cell lines were used as the model system in vitro and RCC xenografts of nude mice were used for in vivo studies. Silibinin inhibited metastasis and epithelial-mesenchymal transition (EMT) of RCC in vitro and in vivo, by regulating the Wnt/β-catenin signaling pathway. Furthermore, silibinin inhibited the Wnt/β-catenin signaling pathway in an autophagy-dependent manner. Autophagic degradation of β-catenin induced by silibinin was associated with the anti-metastatic effects of silibinin against RCC. These findings identify a novel mechanism by which silibinin inhibits EMT and metastasis of RCC, highlighting a potential novel strategy for treating metastatic RCC.

Histone deacetylase inhibitors dysregulate DNA repair proteins and antagonize metastasis-associated processes

Purpose

We set out to determine whether clinically tested epigenetic drugs against class I histone deacetylases (HDACs) affect hallmarks of the metastatic process.

Methods

We treated permanent and primary renal, lung, and breast cancer cells with the class I histone deacetylase inhibitors (HDACi) entinostat (MS-275) and valproic acid (VPA), the replicative stress inducer hydroxyurea (HU), the DNA-damaging agent cis-platinum (L-OHP), and the cytokine transforming growth factor-β (TGFβ). We used proteomics, quantitative PCR, immunoblot, single cell DNA damage assays, and flow cytometry to analyze cell fate after drug exposure.

Results

We show that HDACi interfere with DNA repair protein expression and trigger DNA damage and apoptosis alone and in combination with established chemotherapeutics. Furthermore, HDACi disrupt the balance of cell adhesion protein expression and abrogate TGFβ-induced cellular plasticity of transformed cells.

Conclusion

HDACi suppress the epithelial–mesenchymal transition (EMT) and compromise the DNA integrity of cancer cells. These data encourage further testing of HDACi against tumor cells.

Electronic supplementary material

The online version of this article (10.1007/s00432-019-03118-4) contains supplementary material, which is available to authorized users.

Cadmium and Lead Decrease Cell-Cell Aggregation and Increase Migration and Invasion in Renca Mouse Renal Cell Carcinoma Cells

Metastatic renal cell carcinoma (RCC) remains an important clinical issue; the 5-year survival rate of patients with metastasis is approximately 12%, while it is 93% in those with localized disease. There is evidence that blood cadmium and lead levels are elevated in RCC. The current studies were designed to assess the impact of cadmium and lead on the progression of RCC. The disruption of homotypic cell-cell adhesion is an essential step in epithelial-to-mesenchymal transition and tumor metastasis. Therefore, we examined the impact of cadmium and lead on the cadherin/catenin complex in Renca cells-a mouse RCC cell line. Lead, but not cadmium, induced a concentration-dependent loss of E-cadherin, while cadmium, but not lead, increased p120-catenin expression, specifically isoform 1 expression. Lead also induced a substantial increase in matrix metalloproteinase-9 levels. Both cadmium and lead significantly decreased the number of Renca cell aggregates, consistent with the disruption of the cadherin/catenin complex. Both metals enhanced wound healing in a scratch assay, and increased cell migration and invasion. These data suggest that cadmium and lead promote RCC progression.

Genitourinary Tumors: Update on Molecular Biomarkers for Diagnosis, Prognosis and Prediction of Response to Therapy

BACKGROUND

Research of biomarkers in genitourinary tumors goes along with the development of complex emerging techniques ranging from next generation sequencing platforms, applied to archival pathology specimens, cytological samples, liquid biopsies, and to patient-derived tumor models.

METHODS

This contribution is an update on molecular biomarkers for diagnosis, prognosis and prediction of response to therapy in genitourinary tumors. The following major topics are dealt with: Immunological biomarkers, including the microbiome, and their potential role and caveats in renal cell carcinoma, bladder and prostate cancers and testicular germ cell tumors; Tissue biomarkers for imaging and therapy, with emphasis on Prostate-specific membrane antigen in prostate cancer; Liquid biomarkers in prostate cancer, including circulating tumor cell isolation and characterization in renal cell carcinoma, bladder cancer with emphasis on biomarkers detectable in the urine and testicular germ cell tumors; and Biomarkers and economic sustainability.

CONCLUSION

The identification of effective biomarkers has become a major focus in cancer research, mainly due to the necessity of selecting potentially responsive patients in order to improve their outcomes, as well as to reduce the toxicity and costs related to ineffective treatments.

Vascular Endothelial Growth Inhibitor, a Cytokine of the Tumor Necrosis Factor Family, is Associated With Epithelial-Mesenchymal Transition in Renal Cell Carcinoma

Previous studies have revealed that the activation of the epithelial-mesenchymal transition (EMT) endows metastatic properties upon cancer cells to promote invasion and migration. In this study, immunohistochemical analysis was performed in 50 cases of clear cell renal cell carcinoma (RCC) and paired normal kidney tissues. We detected the expression of vascular endothelial growth inhibitor (VEGI) and EMT markers (E-cadherin, fibronectin, and Slug) and recorded the clinical, pathologic, and follow-up (median follow-up: 79.0 mo) information. The expression of VEGI and E-cadherin was significantly lower in RCC tissues compared with normal kidney tissues (P<0.001). However, the expression of fibronectin and Slug was higher in RCC tissues (P<0.05). VEGI and EMT marker expression marginally differed in tumor size and stage. Significant differences were found in the pathologic grade (P<0.05). The Spearman correlation analysis suggested a positive correlation between VEGI and E-cadherin (r=0.451, P<0.01). A negative correlation was shown between VEGI and fibronectin (r=-0.465, P<0.01). There was also a negative correlation between VEGI and Slug (r=-0.758, P<0.01). During the 79.0 months (range, 7 to 119 mo) of follow-up, 6 patients died due to RCC, and the tumor-free survival rate was 88% (44/50). We did not find a significant correlation between VEGI/EMT markers (E-cadherin, fibronectin, and Slug) and overall survival (P>0.05). Our findings indicate that VEGI plays an important role in EMT in RCC. It suggests that VEGI may be investigated as a disease biomarker and therapeutic target in RCC.

Impact of eIF4E phosphorylation at Ser209 via MNK2a on tumour recurrence after curative surgery in localized clear cell renal cell carcinoma

Background: We investigated the roles of eIF4E phosphorylation (Ser209) in tumour recurrence after curative nephrectomy for localized clear cell renal cell carcinoma (ccRCC).

Methods: Expression of eIF4E, p eIF4E and MNKs (MAPK interacting kinases), was evaluated in surgical specimens obtained from consecutive non metastatic ccRCC patients (n = 290) by immunohistochemistry (IHC), immunoblotting, and qRT PCR at the protein and mRNA levels. In human RCC cell lines, the effects of eIF4E phosphorylation were examined using immunoblotting, proliferation, migration and invasion assays with pharmacological inhibitors (CGP57380 or ETP45835) and specific small interfering (si) RNAs against MNK1/2(a/b).

Results: In postoperative follow-up (median, 7.9 y), 40 patients experienced metastatic recurrence. In multivariate Cox analyses, higher IHC expression of p eIF4E in ccRCC significantly predicted a longer recurrence-free interval. eIF4E is phosphorylated mainly by MNK2a in tumour specimens and cell lines. In 786-O and A-498 cell lines, pharmacological inhibition of MNKs decreased p-eIF4E and increased vimentin and N cadherin but did not influence proliferation. Similarly, MNK2 or MNK2a inhibition with siRNA reduced p-eIF4E and enhanced vimentin translation, cell migration and invasion in the cell lines.

Conclusions: MNK2a-induced eIF4E phosphorylation may suppress metastatic recurrence of ccRCC, partially due to vimentin downregulation at the translational level, consequently leading to inhibition of epithelial–mesenchymal transition.

Allosteric and ATP-Competitive Inhibitors of mTOR Effectively Suppress Tumor Progression-Associated Epithelial-Mesenchymal Transition in the Kidneys of Tsc2+/- Mice

In tuberous sclerosis (TSC)–associated tumors, mutations in the TSC genes lead to aberrant activation of the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway. mTORC1 signaling impacts many biological processes including the epithelial-mesenchymal transition (EMT), which is suggested to promote tumor progression and metastasis in various types of cancer. In this study, we report hybrid cells with epithelial and mesenchymal features in angiomyolipomas and partial EMT in carcinomas from TSC patients and describe a new model of EMT activation during tumor progression from cyst to papillary adenoma to solid carcinoma in the kidneys of Tsc2^+/− mice. Features of EMT occurred infrequently in TSC-associated cysts but increased as the lesions progressed through papillary adenoma to solid carcinoma where epithelial-mesenchymal hybrid cells were abundant, indicating partial EMT. We also compared the effects of the novel ATP-competitive mTOR inhibitor AZD2014 with the allosteric mTOR inhibitor rapamycin on EMT and tumor burden. Both AZD2014 and rapamycin potently suppressed EMT of renal tumors and effectively blocked tumor progression in Tsc2^+/− mice. These results suggest that partial EMT is a shared feature of TSC-associated renal tumors in humans and mice and occurs during TSC-associated tumor progression. EMT-related signaling pathways may represent therapeutic targets for tumors associated with mutations in the TSC genes.

Limitations to the Therapeutic Potential of Tyrosine Kinase Inhibitors and Alternative Therapies for Kidney Cancer

Background: Renal cell carcinomas (RCCs) are the most common primary renal tumor. RCCs have a high rate of metastasis and have the highest mortality rate of all genitourinary cancers. They are often diagnosed late when metastases have developed, and these metastases are difficult to treat successfully. Since 2006, the standard first-line treatment for patients with metastatic RCC has been multitargeted tyrosine kinase inhibitors (TKIs) that include mammalian target of rapamycin (mTOR) inhibitors. RCCs are highly vascularized tumors, and their angiogenesis is controlled by tyrosine kinases that play a vital role in growth factor signaling to stimulate this process. TKI therapy was introduced for direct targeting of angiogenesis in RCC. TKIs have been moderately successful in the treatment of metastatic RCC and initially increased cancer-specific survival times. However, RCC rapidly becomes resistant to TKIs, and no current drug has produced a cure for advanced RCC. Methods: We provide an overview of RCC, explain some reasons for therapy resistance in RCC, and describe some therapies that may overcome resistance to TKIs. The key pathways that determine therapy resistance are illustrated. Results: Factors involved in the development and progression of RCC include genetic mutations, activation of hypoxia-inducible factor and related proteins, cellular metabolism, the tumor microenvironment, and growth factors and their receptors. Resistance to the therapeutic potential of TKIs can be acquired or intrinsic. Alternative therapies include other small molecule drugs and immunotherapy based on immune checkpoint blockade. Conclusion: The treatment of RCC is undergoing a paradigm shift from sole use of small molecule antiangiogenesis TKIs as first-line therapy to include newly approved agents for second-line and third-line therapy that now involve the mTOR pathway and immune checkpoint blockade drugs for patients with advanced RCC.

Molecular Mechanisms in Clear Cell Renal Cell Carcinoma: Role of miRNAs and Hypermethylated miRNA Genes in Crucial Oncogenic Pathways and Processes

Clear cell renal cell carcinoma (ccRCC) is the third most common urological cancer, and it has the highest mortality rate. The increasing drug resistance of metastatic ccRCC has resulted in the search for new biomarkers. Epigenetic regulatory mechanisms, such as genome-wide DNA methylation and inhibition of protein translation by interaction of microRNA (miRNA) with its target messenger RNA (mRNA), are deeply involved in the pathogenesis of human cancers, including ccRCC, and may be used in its diagnosis and prognosis. Here, we review oncogenic and oncosuppressive miRNAs, their putative target genes, and the crucial pathways they are involved in. The contradictory behavior of a number of miRNAs, such as suppressive and anti-metastatic miRNAs with oncogenic potential (for example, miR-99a, miR-106a, miR-125b, miR-144, miR-203, miR-378), is examined. miRNAs that contribute mostly to important pathways and processes in ccRCC, for instance, PI3K/AKT/mTOR, Wnt-β, histone modification, and chromatin remodeling, are discussed in detail. We also separately consider their participation in crucial oncogenic processes, such as hypoxia and angiogenesis, metastasis, and epithelial-mesenchymal transition (EMT). The review also considers the interactions of long non-coding RNAs (lncRNAs) and miRNAs of significance in ccRCC. Recent advances in the understanding of the role of hypermethylated miRNA genes in ccRCC and their usefulness as biomarkers are reviewed based on our own data and those available in the literature. Finally, new data and perspectives concerning the clinical applications of miRNAs in the diagnosis, prognosis, and treatment of ccRCC are discussed.

LncRNA PVT1 promotes proliferation, invasion and epithelial-mesenchymal transition of renal cell carcinoma cells through downregulation of miR-16-5p

Background

LncRNAs have recently emerged as vital regulators in the pathogenesis and development of various cancers. LncRNA PVT1 is reported to function as an oncogene in some tumors. However, the role of PVT1 in RCC remains unknown.

Purpose

To explore the potential effects of lncPVT1 on the development of renal cell carcinoma.

Methods

The expression of PVT1 in renal cancer cell lines and tissues was measured by qRT-PCR. The endogenous PVT1 was silenced by RNAi. Cell viabilities were measured by the MTT assay. The migration and invasion of cells were investigated by the transwell assay. The apoptosis of cells was measured by the Nucleosome ELISA and caspase-3 activity assays. The levels of proteins were measured by the western blot.

Results

We found that PVT1 was upregulated in RCC tissues compared with the adjacent normal tissues. PVT1 expression was closely correlated with TNM stage, Fuhrman grade, lymph node metastasis and tumor size. Kaplan–Meier analysis revealed that high expression of PVT1 was significantly associated with poor overall survival. In accordance, overexpression of PVT1 was observed in RCC cells comto HK-2 cell. Silencing of PVT1 significantly repressed cell viability, induced apoptosis and inhibited cell migration and invasion in vitro. Furthermore, bioinformatic analysis and luciferase reporter assay confirmed that miR-16-5p was a target of PVT1. Silencing of miR-16-5p mostly reversed the regulatory effects on RCC cells induced by downregulation of PVT1.

Conclusion

In summary, our study indicates that targeting PVT1 might represent a rational therapeutic strategy for RCC.

TGF-β inducible epithelial-to-mesenchymal transition in renal cell carcinoma

Epithelial-to-mesenchymal transition (EMT) is a crucial step in cancer progression and the number one reason for poor prognosis and worse overall survival of patients. Although this essential process has been widely studied in many solid tumors as e.g. melanoma and breast cancer, more detailed research in renal cell carcinoma (RCC) is required, especially for the major EMT-inducer transforming growth factor beta (TGF-β). Here, we provide a study of six different RCC cell lines of two different RCC subtypes and their response to recombinant TGF-β1 treatment. We established a model system shifting the cells to a mesenchymal cell type without losing their mesenchymal character even in the absence of the external stimulus. This model system forms a solid basis for future studies of the EMT process in RCCs to better understand the molecular basis of this process responsible for cancer progression.

NDNF inhibits the migration and invasion of human renal cancer cells through epithelial-mesenchymal transition

Neuron-derived neurotrophic factor (NDNF) is a glycosylated, disulfide-bonded secretory protein that contains a fibronectin type III domain. NDNF has been identified as a neurotrophic factor; however, its role in carcinogenesis has not yet been identified. To investigate the expression and role of NDNF in carcinogenesis, the expression of NDNF in human Renal cell carcinoma (RCC) cell lines and tissues was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis. Cell proliferation was investigated using CCK-8 and colony formation assays, and the cell invasion and immigration capacity was evaluated using the transwell assay. The results demonstrated that NDNF expression was downregulated in RCC cell lines and RCC tissues. Restoring NDNF expression significantly inhibited the proliferation, migration and invasion of RCC cells. The study also demonstrated that the inhibitory effect of NDNF on invasive ability was mediated by suppressing the epithelial-mesenchymal transition (EMT) in RCC cells. NDNF may therefore be considered an important regulator of EMT in RCC progression and may represent a novel promising target for antimetastatic therapy.