Current and Emerging Therapeutic Targets for Metastatic Renal Cell Carcinoma

Integrated multi-omics analyses reveal that BCAM is associated with epigenetic modification and tumor microenvironment subtypes of clear cell renal cell carcinoma

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is the most common and highly heterogeneous subtype of renal cell carcinoma. Dysregulated basal cell adhesion molecule (BCAM) gene is associated with poor prognosis in various cancers. However, the dysregulated functions and related multi-omics features of BCAM in ccRCC stay unclear.

RESULTS

BCAM expression was aberrantly downregulated in ccRCC and correlated with adverse pathological parameters and poor prognosis. Low mRNA expression of BCAM was remarkably associated with its CpG methylation levels and BAP1 mutation status. Patients with lower-expressed BCAM concomitant with BAP1 mutation had a worse prognosis. Using RNA-seq data from The cancer genome atlas, we found that compared to the BCAM-high expression subgroup, ccRCC patients in the BCAM-low expression subgroup had significantly higher levels of immune infiltration, higher immune checkpoint expression levels and lower TIDE (tumor immune dysfunction and exclusion) score, indicating potential better response to immunotherapy. Data from the Clinical Proteomic Tumor Analysis Consortium further validated the association between low BCAM expression and CD8 + inflamed phenotype at protein level. Meanwhile, our results suggested that the angiogenesis-related pathways were enriched in the BCAM-high expression subgroup. More importantly, according to the data from the GDSC database, we revealed that the BCAM-high expression subgroup should be more sensitive to anti-angiogenetic therapies, including sorafenib, pazopanib and axitinib.

CONCLUSIONS

These results suggest that BCAM could serve as a biomarker distinguishing different tumor microenvironment phenotypes, predicting prognosis and helping therapeutic decision-making for patients with ccRCC.

DNA methylation of Hugl-2 is a prognostic biomarker in kidney renal clear cell carcinoma

It has been reported that loss of Hugl-2 contributes to tumour formation and progression in vitro and in vivo. However, whether Hugl-2 levels decrease during kidney renal clear cell carcinoma (KIRC) and the mechanism involved remain unknown. This study aimed to investigate whether DNA methylation of Hugl-2 reduces its expression, leading to the progression and poor prognosis of KIRC. Hugl-2 methylation and mRNA expression and KIRC clinicopathological data were extracted from The Cancer Genome Atlas (TCGA), and relationships among these factors were analyzed using UALCAN, MethHC, Wanderer and LinkedOmics web tools. We found that Hugl-2 mRNA and protein levels were reduced in KIRC tissues. Moreover, Hugl-2 mRNA levels were related to tumour grade and overall survival, and Hugl-2 methylation was increased in KIRC. According to the results of methylation-specific PCR, KIRC cells had higher Hugl-2 DNA methylation levels than HKC cells. Moreover, Hugl-2 DNA methylation correlated negatively with Hugl-2 mRNA and was also related to the pathology and T stage of KIRC patients. KIRC patients with high Hugl-2 DNA methylation also had shorter overall survival. Additionally, methylation of cg08827674, a Hugl-2 probe, was related to pathologic stage, T stage, neoplasm histologic grade, serum calcium level without laterality, M stage, N stage, and ethnicity. Furthermore, treatment with the DNA methylation inhibitor decitabine resulted in upregulation of Hugl-2 mRNA and protein levels in KIRC cell lines. These results indicate that Hugl-2 DNA methylation may be both a prognostic marker and a therapeutic target in KIRC.

CircAKT1 acts as a sponge of miR-338-3p to facilitate clear cell renal cell carcinoma progression by up-regulating CAV1

Circular RNAs (CircRNAs) have become a research focus for their important implication in tumorigenesis and cancer progression. This study intends to observe the function of circAKT1 in clear cell renal cell carcinoma (ccRCC) and its underlying molecular mechanism. In the present study, we confirmed the up-regulation of circAKT1 in ccRCC tissues and cells. High circAKT1 expression was positively associated with TNM stage, lymph node metastasis and predicted an adverse prognosis. Functionally, knockdown of circAKT1 suppressed cell proliferation, colony formation, migration, invasion and EMT in vitro. Mechanistic analysis uncovered that circAKT1 could act as a sponge for miR-338-3p to prevent the degradation of caveolin-1 (CAV1). Interestingly, the anti-neoplastic effect of circAKT1 knockdown on ccRCC was abated due to miR-338-3p down-regulation or CAV1 overexpression. To summarize, circAKT1 facilitated ccRCC progression at least partly by sequestering miR-338-3p to up-regulate CAV1 expression. Our findings raised the possibility of exploiting circAKT1 as a potential prognostic biomarker and therapeutic target in ccRCC.

Cell Polarity Protein Pals1-Associated Tight Junction Expression Is a Favorable Prognostic Marker in Clear Cell Renal Cell Carcinoma

Introduction: The Pals1-associated tight junction (PATJ) is a Crumbs (CRB) complex component that regulates epithelial cell apico-basal polarity and directional migration. This study assessed PATJ expression in clear cell renal cell carcinoma (ccRCC) vs. normal tissues and associated with ccRCC progression and prognosis. Methods: The effects of PATJ knockdown were investigated on regulation of normal kidney epithelial cell viability and protein expression in vitro. The PATJ mRNA data in ccRCC were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases and analyzed with UALCAN, LinkedOmics, Kaplan-Meier Plotter, GEPIA, and SurvExpress tools. Immunohistochemistry was performed for PATJ in tissue microarray sections (n = 150 ccRCC and 30 normal renal specimens). Normal human kidney tubular epithelial cell (HKC) cells were transfected with PATJ and negative control siRNA for cell viability CCK-8 assay, flow cytometry, and western blots. Results: The data showed that PATJ mRNA and protein were downregulated in ccRCC tissues and cell lines. Downregulation of PATJ mRNA was associated with male patients, advanced tumor stages, grades, and ccB subtypes as well as poorer overall and disease-free survival of patients. Furthermore, PATJ protein was also significantly downregulated in ccRCC tissues and associated with advanced tumor pathologic, TNM stages and poorer overall. In vitro, knockdown of PATJ expression promoted HKC proliferation and the activation of mitogen-activated protein kinases (MAPK) pathway proteins. Conclusions: This study revealed that a decrease of PATJ in ccRCC, which was associated with male patients, advanced tumor, and poorer survival, suggesting that PATJ may be a useful prognostic biomarker and therapeutic target for ccRCC.

Oral intake of royal jelly improves anti-cancer effects and suppresses adverse events of molecular targeted therapy by regulating TNF-α and TGF-β in renal cell carcinoma: A preliminary study based on a randomized double-blind clinical trial

Molecular targeted therapies are commonly used in patients with metastatic renal cell carcinoma (RCC). However, the efficacy and safety of these therapeutic interventions require enhancement to improve prognosis in these patients. Royal jelly (RJ) has anti-cancer effects and adverse events across a variety of types of malignancy. The present study investigated the detailed mechanism underlying the effects of oral administration of RJ in patients with advanced RCC that were treated with molecular targeted agents in a randomized clinical trial. The study cohort comprised 16 patients treated with RJ and 17 patients treated with a placebo. Serum levels of tumor necrosis factor (TNF)-α and transforming growth factor (TGF)-β were measured using enzyme-linked immunosorbent assays. The results of the present study demonstrated a larger decrease in tumor size upon supplementing patients with RJ following molecular targeted therapy compared with that in patients administered with the placebo. Patients exhibited reduced anorexia and fatigue in the RJ group compared with the placebo group. The relative dose intensity for patients in the RJ group was higher than that in patients in the placebo group. Post- and pre-treatment ratios of the serum levels of TNF-α and TGF-β in patients in the RJ group were lower than those in patients in the placebo group, and these ratios correlated with decreasing tumor size and frequency of anorexia or fatigue in patients. In conclusion, the results of the present study indicated that oral intake of RJ improved the efficacy and safety of molecular targeted therapy in patients with RCC and changed the levels of TNF-α and TGF-β in the serum of patients, which is speculated to serve an important role in RJ-induced biological activities.

TUBB3 Is Associated with High-Grade Histology, Poor Prognosis, p53 Expression, and Cancer Stem Cell Markers in Clear Cell Renal Cell Carcinoma

BACKGROUND

βIII-Tubulin, encoded by the TUBB3 gene, is a microtubule protein. Several studies have shown that overexpression of TUBB3 is linked to poor prognosis and is involved in taxane resistance in some cancers.

OBJECTIVE

The aim of this study was to analyze the expression and function of TUBB3 in clear cell renal cell carcinoma (ccRCC).

METHODS

The expression of TUBB3 was determined using immuno-histochemistry in ccRCC specimens. The effects of TUBB3 knockdown on cell growth and invasion were evaluated in RCC cell lines. We analyzed the interaction between TUBB3, p53, cancer stem cell markers, and PD-L1.

RESULTS

In 137 cases of ccRCC, immunohistochemistry showed that 28 (20%) of the ccRCC cases were positive for TUBB3. High TUBB3 expression was significantly correlated with high nuclear grade, high T stage, and N stage. A Kaplan-Meier analysis showed that high expression of TUBB3 was associated with poor overall survival after nephrectomy. In silico analysis also showed that high TUBB3 expression was correlated with overall survival. Knockdown of TUBB3 suppressed cell growth and invasion in 786-O and Caki-1 cells. High TUBB3 expression was associated with CD44, CD133, PD-L1, and p53 in ccRCC. We generated p53 knockout cells using the CRISPR-Cas9 system. Western blotting revealed that p53 knockout upregulated the expression of TUBB3.

CONCLUSION

These results suggest that TUBB3 may play an oncogenic role and could be a potential therapeutic target in ccRCC.

Development and validation of a robust multigene signature as an aid to predict early relapse in stage I-III clear cell and papillary renal cell cancer

Background and objectives: Multi-gene signature can be used as prognostic indicator in many types of cancer, but the association with early-relapse in patients with stage I-III clear cell and papillary renal cell cancer (RCC) is unknown. We aim to establish a mRNAs signature for improving prediction of early-relapse in patients with stage I-III clear cell and papillary RCC.

Methods: The data of 610 patients with stage I-III RCC from The Cancer Genome Atlas (TCGA) and 270 patients from Fudan University Shanghai Cancer Center (FUSCC) were extracted. Propensity score matching analysis, linear models for microarray data VOOM method, least absolute shrinkage and selection operation Cox regression modeling analysis was conducted in turn for selecting multi-mRNA signature. Survival differences were assessed by Kaplan-Meier estimate and compared using log-rank test. Multivariable Cox regression and time-dependent receiver operating characteristic curves were used to evaluate the association of mRNAs signature with relapse-free survival (RFS).

Results: Seventeen mRNAs were identified to constitute the early-relapse signature. Among patients with stage I-III RCC, those with high-risk score calculated from 17 mRNAs signature showed shorter RFS than those with low-risk score, both in TCGA discovery and internal validation sets, and in FUSCC discovery and internal validation sets (all p < 0.05). In multivariable Cox regression analysis, the 17 mRNAs signature remained an independent prognostic factor both in TCGA discovery (HR 2.43, 95%CI 1.98-2.96) and internal validation sets (HR 1.66, 95%CI 1.19-2.30), and FUSCC discovery (HR 1.28, 95%CI 1.13-1.43) and internal validation sets (HR 1.65, 95%CI 1.11-2.48). Additionally, the 17 mRNAs signature achieved a higher accuracy for RFS estimation beyond clinical indicator.

Conclusion: The 17 mRNAs signature could classify stage I-III RCC patients into low- or high-risk of early-relapse, and will help to guide interventions to optimize survival outcomes.

Emerging therapeutic agents for genitourinary cancers

The treatment of genitourinary malignancies has dramatically evolved over recent years. Renal cell carcinoma, urothelial carcinoma of the bladder, and prostate adenocarcinoma are the most commonly encountered genitourinary malignancies and represent a heterogeneous population of cancers, in both histology and approach to treatment. However, all three cancers have undergone paradigm shifts in their respective therapeutic landscapes due to a greater understanding of their underlying molecular mechanisms and oncogenic drivers. The advance that has gained the most recent traction has been the advent of immunotherapies, particularly immune checkpoint inhibitors. Immunotherapy has increased overall survival and even provided durable responses in the metastatic setting in some patients. The early success of immune checkpoint inhibitors has led to further drug development with the emergence of novel agents which modulate the immune system within the tumor microenvironment. Notwithstanding immunotherapy, investigators are also developing novel agents tailored to a variety of targets including small-molecule tyrosine kinase inhibitors, mTOR inhibitors, and novel fusion proteins to name a few. Erdafitinib has become the first targeted therapy approved for metastatic bladder cancer. Moreover, the combination therapy of immune checkpoint inhibitors with targeted agents such as pembrolizumab or avelumab with axitinib has demonstrated both safety and efficacy and just received FDA approval for their use. We are in an era of rapid progression in drug development with multiple exciting trials and ongoing pre-clinical studies. We highlight many of the promising new emerging therapies that will likely continue to improve outcomes in patients with genitourinary malignancies.

DNA methylation of CRB3 is a prognostic biomarker in clear cell renal cell carcinoma

Our previous study revealed that CRB3 protein expression was reduced in clear cell renal cell carcinoma (ccRCC) and was associated with TNM stage, pathological grade, and poor prognosis of ccRCC. This study aimed to investigate if DNA methylation of CRB3 decreases its expression, subsequently leading to the progression and poor prognosis of ccRCC. Data for DNA methylation of CRB3, CRB3 mRNA expression, and ccRCC clinicopathological parameters were extracted from the cancer genome atlas (TCGA) database. The relationships among DNA methylation of CRB3, CRB3 mRNA expression, and ccRCC clinicopathological parameters were analyzed using UALCAN, MethHC, LinkedOmics, and Wanderer. We found that CRB3 mRNA levels were lower in ccRCC compared to normal tissues. Methylation of CRB3 increased in ccRCC, with all probes showing differences between ccRCC and normal tissues. Furthermore, CRB3 DNA methylation negatively correlated with CRB3 mRNA expression. CRB3 DNA methylation was also related to pathologic stage, T stage, N stage, and M stage of ccRCC. Overall survival was shorter in ccRCC patients with high CRB3 DNA methylation compared to ccRCC patients with low CRB3 DNA methylation. Methylation of cg24798010, a CRB3 probe, was related to laterality, pathologic stage, T stage, M stage, neoplasm-histologic-grade without N stage, and race. Furthermore, treatment with the DNA methylation inhibitor Decitabine resulted in the upregulation of CRB3 mRNA in ccRCC cell lines. These results indicate that DNA methylation of CRB3 may be both a prognostic marker and therapeutic target for ccRCC.

Oral Intake of Royal Jelly Has Protective Effects Against Tyrosine Kinase Inhibitor-Induced Toxicity in Patients with Renal Cell Carcinoma: A Randomized, Double-Blinded, Placebo-Controlled Trial

Background: Although tyrosine kinase inhibitors (TKIs) are still recommended as the standard therapy in renal cell carcinoma (RCC), the high frequency of adverse events is a weakness of this therapy. Because royal jelly (RJ) possesses anti-inflammatory and antioxidant properties, we assessed its protective effects on TKI-induced toxicities in RCC patients. Methods: We enrolled 33 patients with advanced RCC who were assigned to start TKI therapy in combination with a randomized, double-blinded, placebo-controlled RJ trial consisting of a placebo group with 17 subjects and an RJ group with 16 subjects. Results: Fatigue and anorexia frequencies in the RJ group were significantly lower than in the placebo group (p = 0.003 and 0.015, respectively). A statistically significant correlation between RJ and fatigue or anorexia was detected in sunitinib-treated patients. The dose reduction- or discontinuation-free periods were significantly longer (p = 0.013) in the RJ group than in the placebo group. Furthermore, similar observations were made in sunitinib-treated patients (p = 0.016). Conclusions: Our clinical trial showed that RJ exerted protective effects against TKI-induced fatigue and anorexia and lowered TKI dose reduction or discontinuation. Hence, RJ is beneficial for maintaining the quality of life and medication compliance in TKI-treated RCC patients.

Long non-coding RNA HOTTIP is upregulated in renal cell carcinoma and regulates cell growth and apoptosis by epigenetically silencing of LATS2

Renal cell carcinoma (RCC) is one of the most aggressive malignancies with increasing incidence worldwide and is characterized by dismal prognosis owing to a lack of early detection and prognostic biomarkers for this fatal disease. Accumulating studies demonstrated that abnormally expressed long non-coding RNAs (lncRNAs) are involved in tumorigenesis and progression. Specifically, HOTTIP is upregulated and exerts oncogenic properties in some cancers. However, its clinical significance, biological functions and molecular mechanisms in RCC have not been studied. In the current study, RT-qPCR was performed to quantify the relative expression of HOTTIP in RCC tissues and cells. Additionally, we explored its clinical value using Fisher's exact test. Moreover, cell growth and apoptosis altered by HOTTIP was evaluated in vitro and in vivo. Mechanistically, RNA immunoprecipitation (RIP) and chromatin immunoprecipitation (ChIP) analysis was used to determine its molecular mechanism in cell growth and apoptosis. As a result, upregulated HOTTIP is closely associated with unfavorable phenotypes in RCC patients. The mechanistic investigations showed that HOTTIP could bind to enhancer of zeste homolog 2 (EZH2) and lysine specific demethylase 1 (LSD1), thereby repressing LATS2 expression. Collectively, our study illustrates how HOTTIP plays an oncogenic role in RCC and may offer a potential therapeutic target for treating this fatal disease.

REGγ deficiency suppresses tumor progression via stabilizing CK1ε in renal cell carcinoma

Renal cell carcinoma (RCC) is the most common malignant disease of kidney in adults. The proteasome activator REGγ was previously reported to promote the degradation of multiple important regulatory proteins and involved in the progression and development of numerous human cancers. Here, we first reported that REGγ was upregulated in RCC and its upregulation was correlated with a poor prognosis in RCC patients. REGγ depletion obviously suppressed RCC cells proliferation in vitro and in vivo. Notably, casein kinase 1ε (CK1ε) was identified as a novel target of REGγ and knockdown of CK1ε effectively abolished the effect of REGγ depletion on RCC cells growth. Importantly, we also observed that REGγ depletion activated Hippo signaling pathway via stabilizing CK1ε in RCC, indicating the cross-talk between REGγ/CK1ε axis and Hippo pathway during RCC development. In conclusion, our findings suggested that REGγ played a pivotal role in the development of RCC and maybe helpful to identify new therapeutic strategies in the treatment of RCC.