Strategy For Renal Cell Carcinoma Research Articles

Multiple factors influence decision making for the surgical treatment in patients with renal cell carcinoma.

Surgical strategy in renal cell carcinoma (RCC) is considered based on the renal function. Partial nephrectomy (PN) preserves kidney function better than radical nephrectomy (RN), lowering risk of chronic kidney disease (CKD). The aim was to evaluate whether renal function and other clinical variables were important for surgical treatment selection. Patients with RCC, surgically treated between 1994 and 2018 were included. There were 663 patients in all stages, 265 women and 398 men, mean age 66 years. estimated glomerular filtration rate (eGFR), WHO performance status (WHO-PS), Charlson comorbidity index (CCI), surgery, T-stage, M-stage, RCC type, tumor size, age, and gender were extracted from the medical records. Statistical analysis included Mann-Whitney U, X2-test, and logistic regression analysis. Of 663 patients, 455 were treated with RN and 208 with PN. In all patients, preoperative eGFR was significantly higher in PN (80.8) than in RN (77.1, p = 0.015). Using logistic regression tumor size (odds ratio [OR]: 0.96; 95% confidence interval [CI]: 0.95-0.98, T-stage (OR: 0.46; 95% CI: 0.33-0.65), WHO-PS (OR: 0.39; 95% CI: 0.04-0.57), and CCI (OR: 1.23; 95% CI: 1.05-1.44), associated to treatment selection, while eGFR, M-stage, age, and gender did not. In cTa subgroup, eGFR was also higher in PN (84.6) than in RN (75.0, p = 0.007). Using logistic regression, tumor size (OR: 0.93; 95% CI: 0.83-0.98) and WHO-PS (OR: 0.36; 95% CI: 0.20-0.66) associated to treatment selection, while eGFR, CCI, age, and gender did not. Tumor size, CCI scores, T-stage, and WHO-PS, all had an impact on the surgical strategy for all RCC patients. In patients with T1a RCC, tumor size and WHO-PS associated independently with treatment decision. After adjusted analysis, renal function lost its independent association with the treatment strategy in RCC patients.

Smarca4 deficiency induces Pttg1 oncogene upregulation and hyperproliferation of tubular and interstitial cells during kidney development.

Kidney formation and nephrogenesis are controlled by precise spatiotemporal gene expression programs, which are coordinately regulated by cell-cycle, cell type-specific transcription factors and epigenetic/chromatin regulators. However, the roles of epigenetic/chromatin regulators in kidney development and disease remain poorly understood. In this study, we investigated the impact of deleting the chromatin remodeling factor Smarca4 (Brg1), a human Wilms tumor-associated gene, in Wnt4-expressing cells. Smarca4 deficiency led to severe tubular defects and a shortened medulla. Through unbiased single-cell RNA sequencing analyses, we identified multiple types of Wnt4 Cre-labeled interstitial cells, along with nephron-related cells. Smarca4 deficiency increased interstitial cells but markedly reduced tubular cells, resulting in cells with mixed identity and elevated expression of cell-cycle regulators and genes associated with extracellular matrix and epithelial-to-mesenchymal transition/fibrosis. We found that Smarca4 loss induced a significant upregulation of the oncogene Pttg1 and hyperproliferation of Wnt4 Cre-labeled cells. These changes in the cellular state could hinder the cellular transition into characteristic tubular structures, eventually leading to fibrosis. In conclusion, our findings shed light on novel cell types and genes associated with Wnt4 Cre-labeled cells and highlight the critical role of Smarca4 in regulating tubular cell differentiation and the expression of the cancer-causing gene Pttg1 in the kidney. These findings may provide valuable insights into potential therapeutic strategies for renal cell carcinoma resulting from SMARCA4 deficiency.

Targeting Alpha-Ketoglutarate Disruption Overcomes Immunoevasion and Improves PD-1 Blockade Immunotherapy in Renal Cell Carcinoma.

The Warburg effect-related metabolic dysfunction of the tricarboxylic acid (TCA) cycle has emerged as a hallmark of various solid tumors, particularly renal cell carcinoma (RCC). RCC is characterized by high immune infiltration and thus recommended for immunotherapeutic interventions at an advanced stage in clinical guidelines. Nevertheless, limited benefits of immunotherapy have prompted investigations into underlying mechanisms, leading to the proposal of metabolic dysregulation-induced immunoevasion as a crucial contributor. In this study, a significant decrease is found in the abundance of alpha-ketoglutarate (αKG), a crucial intermediate metabolite in the TCA cycle, which is correlated with higher grades and a worse prognosis in clinical RCC samples. Elevated levels of αKG promote major histocompatibility complex-I (MHC-I) antigen processing and presentation, as well as the expression of β2-microglobulin (B2M). While αKG modulates broad-spectrum demethylation activities of histone, the transcriptional upregulation of B2M is dependent on the demethylation of H3K4me1 in its promoter region. Furthermore, the combination of αKG supplementation and PD-1 blockade leads to improved therapeutic efficacy and prolongs survival in murine models when compared to monotherapy. Overall, the findings elucidate the mechanisms of immune evasion in anti-tumor immunotherapies and suggest a potential combinatorial treatment strategy in RCC.

HOOK1 Inhibits the Progression of Renal Cell Carcinoma via TGF-β and TNFSF13B/VEGF-A Axis.

Accumulating evidence shows HOOK1 disordered in human malignancies. However, the clinicopathological and biological significance of HOOK1 in renal cell carcinoma (RCC) remains rarely studied. In this study, the authors demonstrate that HOOK1 is downregulated in RCC samples with predicted poorer clinical prognosis. Mechanistically, HOOK1 inhibits tumor growth and metastasis via canonical TGF-β/ALK5/p-Smad3 and non-canonical TGF-β/MEK/ERK/c-Myc pathway. At the same time, HOOK1 inhibits RCC angiogenesis and sunitinib resistance by promoting degradation of TNFSF13B through the ubiquitin-proteasome pathway. In addition, HOOK1 is transcriptionally regulated by nuclear factor E2F3 in VHL dependent manner. Notably, an agonist of HOOK1, meletin, is screened and it shows antitumor activity more effectively when combined with sunitinib or nivolumab than it is used alone. The findings reveal a pivotal role of HOOK1 in anti-cancer treatment, and identify a novel therapeutic strategy for renal cell carcinoma.

New insights into fibrotic signaling in renal cell carcinoma.

Fibrotic signaling plays a pivotal role in the development and progression of solid cancers including renal cell carcinoma (RCC). Intratumoral fibrosis (ITF) and pseudo-capsule (PC) fibrosis are significantly correlated to the disease progression of renal cell carcinoma. Targeting classic fibrotic signaling processes such as TGF-β signaling and epithelial-to-mesenchymal transition (EMT) shows promising antitumor effects both preclinically and clinically. Therefore, a better understanding of the pathogenic mechanisms of fibrotic signaling in renal cell carcinoma at molecular resolution can facilitate the development of precision therapies against solid cancers. In this review, we systematically summarized the latest updates on fibrotic signaling, from clinical correlation and molecular mechanisms to its therapeutic strategies for renal cell carcinoma. Importantly, we examined the reported fibrotic signaling on the human renal cell carcinoma dataset at the transcriptome level with single-cell resolution to assess its translational potential in the clinic.

Research Progress on Ferroptosis as a Therapeutic Strategy in Renal Cell Carcinoma

Renal cell carcinoma (RCC) is a common type of kidney cancer in adults and constitutes approximately 90% of all renal malignancies. Although advancements have been made in the treatment of RCC, the 5 -year survival rate is still low, and new treatment modalities are still required. Ferroptosis is an iron-dependent programmed cell death caused by the accumulation of lipid peroxide products. Recent studies revealed the involvement of ferroptosis metabolism, lipid peroxidation, and System XC-GSH-GPX4 shafts as major mechanisms closely related to RCC progression. Nanoparticles in combination with small molecular ferroptosis induction agents have the advantages of solubility, targeted enhancement, low systemic toxicity, controllable drug control, and synergy advantage in emerging combination therapies. In the future, it is possible to be used in nano treatment. The relationship between ferroptosis-related mechanisms and RCC progression and its role in the treatment could provide novel treatment strategies for patients with advance-stage RCC.

In vivo characterization of glutamine metabolism identifies therapeutic targets in clear cell renal cell carcinoma.

Targeting metabolic vulnerabilities has been proposed as a therapeutic strategy in renal cell carcinoma (RCC). Here, we analyzed the metabolism of patient-derived xenografts (tumorgrafts) from diverse subtypes of RCC. Tumorgrafts from VHL-mutant clear cell RCC (ccRCC) retained metabolic features of human ccRCC and engaged in oxidative and reductive glutamine metabolism. Genetic silencing of isocitrate dehydrogenase-1 or isocitrate dehydrogenase-2 impaired reductive labeling of tricarboxylic acid (TCA) cycle intermediates in vivo and suppressed growth of tumors generated from tumorgraft-derived cells. Glutaminase inhibition reduced the contribution of glutamine to the TCA cycle and resulted in modest suppression of tumorgraft growth. Infusions with [amide-15N]glutamine revealed persistent amidotransferase activity during glutaminase inhibition, and blocking these activities with the amidotransferase inhibitor JHU-083 also reduced tumor growth in both immunocompromised and immunocompetent mice. We conclude that ccRCC tumorgrafts catabolize glutamine via multiple pathways, perhaps explaining why it has been challenging to achieve therapeutic responses in patients by inhibiting glutaminase.

Capsaicin inhibits the migration, invasion and EMT of renal cancer cells by inducing AMPK/mTOR-mediated autophagy

Capsaicin (CAP), extracted from Capsicum fruits, has been reported to exhibit antitumor effects in various lines of cancer cells. However, the mechanism underlying its antitumor efficiency is not fully understood. Autophagy is a fundamental self-degradation process of cells that maintains homeostasis and plays a controversial role in tumor initiation and progression. The EMT is defined as a system regulating cells transformed from an epithelial-like phenotype into a mesenchymal phenotype by several internal and external factors, following the metastatic performance of the cells developed. The present study aimed to investigate the potential role of autophagy in CAP-induced antitumor effects in renal cell carcinoma (RCC) 786-O and CAKI-1 cell lines. The results revealed that CAP remarkably inhibited the migration and invasion of RCC cells in vitro and metastasis in vivo. Moreover, we found that the CAP treatment increased the formation of autophagolysosome vacuoles and LC3 yellow and red fluorescent puncta in RCC cells and upregulated the expression of LC3, suggesting that autophagy was induced by CAP in 786-O and CAKI-1 cell lines. Our further results demonstrated that CAP-induced autophagy was mediated by the AMPK/mTOR pathway. In conclusion, our study provides new knowledge of the potential relationship between autophagy and metastasis inhibition induced by CAP, which might be a promising therapeutic strategy in RCC.

Targeting an IL-6/JAK/STAT/PIM1 pathway in renal cell carcinoma.

376 Background: Renal cell carcinoma (RCC) is the most common cancer of the kidney and accounts for over 430,000 new cases worldwide and 179,000 deaths each year. PIM1 overexpression is associated with poor clinical outcomes in patients with RCC. PIM1 is a constitutively active effector serine/threonine kinase with roles in tumor progression including cell proliferation, apoptosis, invasion, and migration. Yet, the mechanisms that underlie PIM1 expression and its function in RCC are not fully understood. Previous studies have implicated the cytokine IL-6 as an activator of STAT3 and stimulator of PIM1 expression in pancreatic cancer. The aim of the present study is to explore expression of PIM1 in RCC and identify potential signaling pathways that influence PIM1 expression. Methods: To evaluate the contribution of PIM1 expression in RCC we first established baseline PIM1 levels across four RCC cell lines (786-O, 769-P, CAKI-1, and RCC-4). Next, we quantified the presence of IL-6 in cell culture supernatants for each cell line using an ELISA assay. IL-6 signals through the JAK/STAT pathway, consequently we then used immunoblotting to determine whether ruxolitinib, a JAK1/2 inhibitor, would affect PIM1 expression. Finally, we examined cell viability post-ruxolitinib therapy using an MTS assay. Results: Our results show that 769-P, 786-O, and CAKI-1 but not RCC-4 cells overexpress PIM1 relative to normal renal proximal tubule epithelial cells. Results from the ELISA assay show that 786-O, CAKI-1, and to a lesser degree RCC-4 cells secrete IL-6 into their media. Interestingly, 769-P cells had little to no IL-6 present in their media. Based on these differences we sought to understand what effect inhibiting JAK may have on PIM1 expression. After treating cells with ruxolitinib, we found that 786-O and CAKI-1 cells show a time and dose dependent decrease in PIM1 levels whereas 769-P cells did not. To understand if these differences correlate with cell viability, we performed an MTS assay after treating cells with ruxolitinib. Preliminary results show that at 8hr post-treatment, CAKI-1 but not 769-P cells display a time and concentration dependent loss of cell viability. Conclusions: Our initial studies suggest that differential expression of PIM1 among RCC cell lines may be linked to autocrine IL-6 secretion. In CAKI-1 cells JAK inhibition decreases PIM1 expression and cell viability. In the context of 769-P cells with high PIM1 expression but low IL-6 secretion levels, JAK inhibition did not affect cell viability. These data suggest that in 769-P cells there exists a non-IL-6 dependent mechanism stimulating PIM1 expression. Further investigation is required to elucidate the contexts of these PIM1 regulatory pathways in order to develop IL-6/JAK/PIM1 targeted anti-cancer strategies in RCC.

Single Fraction Stereotactic Body Radiation Therapy Induces Dynamic Changes to the Peripheral Blood T Cell Repertoire in Renal Cell Carcinoma Patients

Clinical studies combining radiation and immunotherapy have shown promising response rates, strengthening efforts to sensitize tumors to immune-mediated attack. Thus, there is an ongoing surge in trials using preconditioning regimens with immunotherapy. Yet, due to scarcity of resected tumors treated in situ with radiotherapy, there has been little investigation of radiation’s sole contributions towards local and systemic anti-tumor immunity in patients. Without this access, translational studies have been limited to evaluating circulating immune subsets and systemic remodeling of peripheral T cell receptor repertoires. This constraint has left gaps in how radiation impacts intratumoral responses and whether tumor-resident T cell clones are amplified following treatment. Therefore, to interrogate the immune impact of radiation on the tumor microenvironment and test the hypothesis that radiation initiates local and systemic expansion of tumor-resident clones, we analyzed renal cell carcinoma from patients treated with stereotactic body radiation therapy. Blood and tumor samples were collected from patients prior to nephrectomy for renal cell carcinoma. These samples were compared to samples from patients treated on a 15 patient clinical trial of single fraction stereotactic body radiation therapy delivered 4 weeks prior to nephrectomy. Transcriptomic comparisons were evaluated by bulk RNA sequencing. T cell receptor sequencing monitored repertoires during the 4-week period between SBRT and nephrectomy. Pathway analysis from tumor transcriptomic data showed radiation-specific enrichment of immune-related processes. T cell receptor sequencing revealed increased clonality in radiation-treated tumors. The frequency of identified, tumor-enriched clonotypes was tracked across serial blood samples. Compared to pre-treatment, we observed increased abundance of tumor-enriched clonotypes 2 weeks post-radiation. However, this expansion was not sustained and contracted towards baseline levels 4 weeks after treatment. Altogether, these results indicate robust intratumoral immune remodeling and a window of tumor-resident T cell expansion following radiation that may be leveraged for rational design of combinatorial strategies. Samples from renal cell carcinoma (RCC) patients underwent high-throughput analysis to reveal transcriptional immune activation and increased clonality in irradiated tumors. Analysis across longitudinal blood samples showed tumor-enriched clonotypes undergo phases of peripheral expansion and contraction following radiation. Collectively, these findings demonstrate radiotherapy remodels intratumoral T cell responses and have significant implications for refined sequencing of combination strategies in RCC.

Systemic Analysis and Review of Nivolumab-ipilimumab Combination as a Rescue Strategy for Renal Cell Carcinoma After Treatment With Anti-PD-1/PD-L1 Therapy.

Nivolumab-ipilimumab has become the standard of care in the frontline setting for intermediate-/poor-risk metastatic renal cell carcinoma (mRCC). This regimen is associated with survival improvement but significant toxicity. Anti-programmed cell death protein 1(PD-1)/programmed death-ligand 1(PD-L1) monotherapy may provide response and offers a better safety profile. In this context, nivolumab-ipilimumab has been postulated as a rescue treatment after anti-PD-1/PD-L1 therapy. Recent retrospective data has shown positive results, and several nonrandomized clinical trials (NRCTs) have evaluated this strategy. Therefore, we performed a meta-analysis of available NRCTs to clarify the efficacy and safety of salvage nivolumab-ipilimumab in mRCC after prior anti-PD-1/PD-L1 monotherapy. We searched PubMed, Medline, Embase, and the Cochrane Central Register of Controlled Trials to identify clinical trials investigating the efficacy and safety of salvage nivolumab-ipilimumab after prior anti-PD-1/PD-L1 in patients with mRCC. Only phase II NRCTs were available for the analysis. The pooled effect of single proportions with a 95% confidence interval (CI) was used as the measure of effect (overall response rate [ORR] and incidence of grade≥ 3 adverse events). Four studies accounting for 237 patients were included. All patients received prior anti-PD-1/PD-L1 monotherapy. The pooled ORR of salvage nivolumab-ipilimumab after prior anti-PD-1/PD-L1 failure was 10.0% (95% CI, 6%-14%; I2= 41%; P= .17). The incidence of grade≥ 3 irAEs was 27.0% (95% CI, 20%-35%; I2= 0%; P= .56). The results of this analysis suggest that the use of salvage nivolumab-ipilimumab in mRCC after prior anti-PD-1/PD-L1 has limited activity with a 10% ORR, and a non-negligible toxicity with 1 of 4 patients developing grade≥ 3 immune-related adverse events.

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

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

Minimally invasive partial nephrectomy versus percutaneous cryoablation for stage Ia renal cell carcinoma: A cost-effectiveness analysis.

e17066 Background: Minimally invasive partial nephrectomy (PN) and percutaneous cryoablation (Cryo) are treatment strategies for renal cell carcinoma (RCC). The purpose of this study is to assess the cost-effectiveness of PN and Cryo for stage Ia RCC. Methods: A decision-analysis model was constructed over 5 years from a health care sector’s perspective using TreeAge Pro Suite 2019 (TreeAge Software LLC, Cambridge, MA). The two evaluated strategies were PN and Cryo. The model incorporated the clinical course of stage Ia RCC after either treatment, including costs and quality of life associated with major complications, imaging surveillance (based on 2014 National Comprehensive Cancer Network guidelines), local and metastatic recurrences, and cancer-specific mortality. All clinical parameters were derived from the literature. A willingness-to-pay threshold of $100,000/quality adjusted life year (QALY) was used. 1 QALY is equivalent to 1 year of life in perfect health. Outcomes were measured by incremental effectiveness ratio. Base case calculations, Monte Carlo Simulations with 10,000 iterations using bootstrapping for parameters from their distributions, and multiple sensitivity analyses were performed. Results: Five-year local recurrence-free, metastasis-free, and cancer-specific survival from recent literature were 97.7% versus 95.9% ( p = 0.18), 98.0% versus 100% ( p = 0.14), 99.3% versus 100% % ( p = 0.7) for PN and Cryo. PN and Cryo yielded similar health benefits of 3.63 QALY and 3.64 QALY. Overall costs were $26,343 and $19,346 for PN and Cryo. A total of 89.28% of the 10,000 simulations showed higher cost-effectiveness of Cryo than PN. One-way sensitivity analyses varying long-term outcomes after Cryo while keeping outcomes after PN constant, revealed that Cryo is more cost-effective than PN when its local recurrence risk is < 3.94% per year (18.2% over 5 years), metastasis risk is < 1.51% per year (7.33% over 5 years), or cancer-specific mortality risk is < 0.96% per year (4.7% over 5 years). PN is more cost-effective if Cryo local recurrence risk is 3.5% higher than PN per year, when the metastasis risk is 1.1% higher than PN per year, or when its cancer-specific mortality is more than 0.9% higher than PN per year. Cryo is more cost-effective than PN if its cost is not more than $1,000 higher than PN. Conclusions: Our study showed that Cryo is more cost-effective than PN for stage Ia RCC patients with comparable effectiveness at a lower cost, based on multiple probabilistic and deterministic sensitivity analyses.

Tumor-Associated Macrophages Induce Migration of Renal Cell Carcinoma Cells via Activation of the CCL20-CCR6 Axis.

This study investigated tumor-associated macrophages activity in the microenvironment of renal cell carcinoma. Via a co-culture with macrophage-like cells differentiated from human monocyte cell line THP-1 and U937 cells, the migration ability of ACHN and Caki-1 cells, which are human renal cell carcinoma cell line cells, was significantly increased, as was the epithelial–mesenchymal transition change. A chemokine array identified the CCL20-CCR6 axis as a concentration-dependent signal in ACHN and Caki-1 cell migration. Akt in the ACHN and Caki-1 cells was activated by macrophage-like cells, and the CCL20 neutralizing antibody suppressed migration ability, epithelial–mesenchymal transition, and Akt phosphorylation in the ACHN and Caki-1 cells. Akt inhibitor AZD5363 also decreased the epithelial–mesenchymal transition change and migration ability in the ACHN and Caki-1 cells. In 42 renal cell carcinoma tissues, patients with CCR6 and macrophage infiltration indicated poor prognoses. In the tumor microenvironment of renal cell carcinoma, cancer cells are activated by CCL20 secreted by tumor-associated macrophages through Akt activation, followed by epithelial–mesenchymal transition and an acquired migration ability. Thus, inhibition of the CCL20-CCR6 axis may be a potential therapeutic strategy for renal cell carcinoma.

Evidence-based follow-up in renal cell carcinoma

The optimal surveillance strategy in renal cell carcinoma after curative resection or ablation is a field of ongoing research. This review discusses the evidence behind routine follow up, duration of follow up, imaging modality and intervals as well as surveillance after local ablative therapy. The recommendations and differences of major guidelines are outlined as well. A risk based approach is advocated taking into account both tumor and patient specific characteristics.

Immunotherapy for genitourinary tumors.

The present review provides an update about the major achievements and recent advances of immunotherapy in renal cell carcinoma, urothelial carcinoma, and prostate cancer. Although the treatment strategy for renal cell carcinoma and urothelial carcinoma includes traditional cancer immunotherapies, such as interleukin-2 and interferon-alfa, the clinical outcomes of these therapies are unsatisfactory. In recent years, the development of immune checkpoint inhibitors has drastically changed the treatment strategy for various cancers, including genitourinary cancer. The present review summarizes the approved cancer immunotherapies for renal cell carcinoma, urothelial carcinoma and prostate cancer. Furthermore, we review the response evaluation and biomarkers for immune checkpoint inhibitors with a distinctive mode of action that is different from cytotoxic agents. Finally, future perspectives for cancer immunotherapy are discussed.

MicroRNA-138 suppresses cell proliferation and invasion of renal cell carcinoma by directly targeting SOX9.

An accumulating number of studies have reported that the expression levels of microRNAs (miRNAs/miRs) are dysregulated in a variety of human cancer types, including renal cell carcinoma (RCC). miRNAs play essential functions in tumorigenesis and the progression of tumors by serving as oncogenes or tumor suppressors. Recently, the expression and functions of miR-138 have been studied in a number of human cancer types; however, its role in RCC remains poorly understood. In the present study, the results revealed that miR-138 was significantly downregulated in RCC cell lines and tissues, and that low expression levels of miR-138 were correlated with histological grade, tumor stage and lymph node metastasis. In functional studies, restoration of miR-138 expression inhibited cell proliferation and invasion of ACHN and A498 cells. In addition, SOX9 was validated as a direct target gene of miR-138 in RCC. SOX9 knockdown inhibited cell proliferation and invasion of RCC, with a similar effect to that induced by miR-138, rendering SOX9 a functional target of miR-138 in the disease. These findings indicate that miR-138 may present a novel target for therapeutic strategies in RCC.

Tissue transglutaminase expression is necessary for adhesion, metastatic potential and cancer stemness of renal cell carcinoma

ABSTRACTTissue transglutaminase (TG2) is the ubiquitously expressed member of transglutaminase family and shown to play a critical role in the development and progression of drug resistance malignancies. We have previously showed the association of TG2 upregulation with progression and metastasis of renal cell carcinoma (RCC) and low disease-free survival. In the present study we further investigate the role of TG2 in cell adhesion, migration and invasion of RCC by silencing TG2 expression in Caki-2 and A-498 primary site and Caki-1 and ACHN metastatic site RCC cell lines. Downregulation of TG2 expression led up to a 60% decrease in actin stress fiber formation and adhesion to β 1 integrin (ITGB1) substrates fibronectin, collagen type I and laminin in both primary and metastatic site RCC cell lines. In addition, treatment with siRNAs against TG2 impaired the migration capacity and cellular invasiveness of ITGB1 substrates in all 4 RCC cell lines. Lastly, the knockdown of TG2 in metastatic Caki-1 cells diminished the expression of CD44, CD73-and CD105 cancer stem cell-like markers. We conclude, for the first time, that TG2 expression is critical for cancer cell adhesion, migration, invasiveness and cancer cell-stemness during RCC progression and dissemination. Therefore, combined targeting of TG2 with drugs widely used in the treatment of RCC may be a promising therapeutic strategy for RCC.

Ecto-5'-nucleotidase (CD73) is a biomarker for clear cell renal carcinoma stem-like cells.

Identification of a specific biomarker for cancer stem cells (CSCs) is of potential applications in the development of effective therapeutic strategies for renal cell carcinoma (RCC). In this study, both the RCC cell line 786-O and surgically removed clear cell RCC (ccRCC) tissues were implemented to grew as spheroids in serum-free medium supplemented with mitogens. This subpopulation possessed key characteristics defining CSCs. We also identified that surgically removed ccRCC tissues were heterogenic and there was a subpopulation of cells that was highly stained with rhodamine-123. Based on membrane-proteomic analyses, CD73 was identified as a candidate biomarker. We further found that CD73high cells were highly tumorigenic. As few as 100 CD73high cells were capable of forming xenograft tumors in non obese diabetic/severe combined immunodeficiency disease mice, whereas 1 × 105 CD73low cells did not initiate tumor formation. During successive culture, the CD73high population regenerated both CD73high and CD73low cells, whereas the CD73low population remained low expression level of CD73. Furthermore, the CD73high cells were more resistant to radiation and DNA-damaging agents than the CD73low cells, and expressed a panel of ‘stemness’ genes at a higher level than the CD73low cells. These findings suggest that a high level of CD73 expression is a bona fide biomarker of ccRCC stem-like cells. Future research will aim at the elucidation of the underlying mechanisms of CD73 in RCC development and the distinct aspects of ccRCC stem-like cells from other tumor types.

The selective MEK1 inhibitor Selumetinib enhances the antitumor activity of everolimus against renal cell carcinoma in vitro and in vivo.

Renal cell carcinoma (RCC) is a urologic malignant cancer and often diagnosed at an advanced stage, which results in high mortality. Targeted therapy may improve the quality of life and survival of patients who are not suitable for nephrectomy. Everolimus, an mTOR inhibitor, is currently used as sequential or second-line therapy for RCC refractory to Sunitinib or sorafenib. However, its efficiency is palliative. In this study, we evaluated whether the antitumor activity of everolimus against RCC is enhanced by selumetinib, a selective MEK1 inhibitor. We discovered that everolimus in combination with selumetinib synergistically inhibited the proliferation of Caki-1, 786-O and 769-P cells in vitro. Mechanistically, this combination decreased p-RPS6 and p-4E-BP1 dramatically, which causes G1 cell cycle arrest and prevents reactivation of AKT and ERK. In vivo, the antitumor efficacy and pharmacodynamic biomarkers of the combination therapy were recapitulated in Caki-1 xenograft model. In addition, this combination treatment potently inhibited angiogenesis in xenograft models by impairing VEGF secretion from tumor cells. Our findings provide a sound evidence that combination of everolimus and selumetinib is a potential dual-targeted strategy for renal cell carcinoma.