Drug resistance in papillary RCC: from putative mechanisms to clinical practicalities

PD-L1 expression and its prognostic value in metastatic papillary renal cell carcinoma: Results from a GETUG multicenter retrospective cohort

INTRODUCTION

Papillary renal cell carcinoma (pRCC) is a rare and aggressive cancer with no specifically established therapeutic strategy in the metastatic setting. Combinations of tyrosine kinase and immune checkpoint inhibitors (ICI) are a promising option. We aimed to study the immune landscape of metastatic pRCC, and its interactions with angiogenesis pathways, to search for potential therapeutic targets.

METHODS

The expression of immune markers (PD-L1, PD-1, PD-L2, LAG-3) and angiogenic pathways (CAIX, c-MET), was analyzed by immunohistochemistry on 68 metastatic pRCC retrieved from a retrospective multicenter GETUG cohort. Our primary endpoint was to estimate the prevalence of PD-L1 expression and its prognostic impact in metastatic pRCC. Secondary endpoints included the evaluation of other immune markers (PD-1, PD-L2, and LAG-3) and their association with PD-L1. We also assessed angiogenic markers and their association with PD-L1.

RESULTS

Overall, 27.9 % of tumors were PD-L1 positive. PD-L2 was more frequently expressed (45.6 %), PD-1 and LAG-3 were positive in 17.6 % and 19.1 % respectively. None of these markers was correlated with PD-L1 expression. 66 % (45/68) expressed at least one immune marker, and 43 % (29/68) were "double-positive", as they expressed both immune and angiogenic markers. OS was significantly shorter for patients with PD-L1 positive pRCC. A multivariate analysis confirmed a significant association between PD-L1 expression and shorter overall survival (HR = 4.0, p = 0.01).

CONCLUSION

These results reinforce clinical data on the expected benefit of ICI in metastatic pRCC treatment, as PD-L1 expression is a factor of poor prognosis in this multicenter cohort.

EMX2 inhibits clear cell renal cell carcinoma progress via modulating Akt/FOXO3a pathway

Empty spiracles homeobox 2 (EMX2) is initially identified as a key transcription factor that plays an essential role in the regulation of neuronal development and some brain disorders. Recently, several studies emphasized that EMX2 could as a tumor suppressor, but its role in human clear cell renal cell carcinoma (ccRCC) remains unclear. In the present study, we investigated the role and underlying mechanism of EMX2 in the regulation of ccRCC progress. Our results demonstrated that EMX2 expression was markedly decreased in ccRCC tissues and cell lines, and low EMX2 expression predicted the poor prognosis of ccRCC patients. In addition, forced expression of EMX2 significantly inhibited the cell growth, migration, and invasion in vitro, as well as ccRCC tumor growth in nude mice, via, at least in part, regulating Akt/FOXO3a pathway. In detail, EMX2 could attenuate the phosphorylation levels of Akt and FOXO3a, and increase FOXO3a expression without affecting total Akt expression in vivo and in vitro. Meanwhile, shRNA-mediated knockdown of FOXO3a expression could obviously attenuate the effects of EMX2 on cell growth, migration, invasion, and tumor growth. Furthermore, EMX2 could significantly attenuate the interaction between Akt and FOXO3a. Taken together, our results demonstrated that EMX2 could inhibit ccRCC progress through, at least in part, modulating Akt/FOXO3a signaling pathway, thus representing a novel role and underlying mechanism of EMX2 in the regulation of ccRCC progress.

Notch activation defines immune-suppressive subsets of ccRCCs with unfavorable benefits from immunotherapy over VEGFR/mTOR inhibitors

The evolutionarily conserved Notch pathway, involved in cancer stem cell capacity and cancer immunity, may predict the benefit from immune checkpoint inhibitors (ICIs) in clear cell renal cell carcinoma (ccRCC). In the TCGA dataset, mRNA expression of Notch pathway genes identified three clusters with different prognoses and molecular characteristics. Based on the differentially expressed Notch pathway genes between clusters, we constructed the Notch-score, correlated with Notch activation, angiogenesis, PI3K-AKT-mTOR activity, and sensitivities to VEGFR/mTOR inhibitors. A high Notch-score was linked with more "resting"/"anti-inflammatory" rather than "activated"/"pro-inflammatory" tumor-infiltrating immune cells, inactivated immune pathways, and scarce any benefits from ICI-based therapies over VEGFR/mTOR inhibitors in the JAVELIN Renal 101 (avelumab plus axitinib vs. sunitinib) and the CheckMate-009/010/025 trials (nivolumab vs. everolimus). For the Notch-activated ccRCCs, ICIs provide limited advantages and might not be strongly recommended, by which the cost-effectiveness of treatments in ccRCCs may be potentially improved.

Ex Vivo Drug Testing in Patient-derived Papillary Renal Cancer Cells Reveals EGFR and the BCL2 Family as Therapeutic Targets

BACKGROUND

Immune checkpoint inhibitors and antiangiogenic agents are used for first-line treatment of advanced papillary renal cell carcinoma (pRCC) but pRCC response rates to these therapies are low.

OBJECTIVE

To generate and characterise a functional ex vivo model to identify novel treatment options in advanced pRCC.

DESIGN, SETTING, AND PARTICIPANTS

We established patient-derived cell cultures (PDCs) from seven pRCC samples from patients and characterised them via genomic analysis and drug profiling.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Comprehensive molecular characterisation in terms of copy number analysis and whole-exome sequencing confirmed the concordance of pRCC PDCs with the original tumours. We evaluated their sensitivity to novel drugs by generating drug scores for each PDC.

RESULTS AND LIMITATIONS

PDCs confirmed pRCC-specific copy number variations such as gains in chromosomes 7, 16, and 17. Whole-exome sequencing revealed that PDCs retained mutations in pRCC-specific driver genes. We performed drug screening with 526 novel and oncological compounds. Whereas exposure to conventional drugs showed low efficacy, the results highlighted EGFR and BCL2 family inhibition as the most effective targets in our pRCC PDCs.

CONCLUSIONS

High-throughput drug testing on newly established pRCC PDCs revealed that inhibition of EGFR and BCL2 family members could be a therapeutic strategy in pRCC.

PATIENT SUMMARY

We used a new approach to generate patient-derived cells from a specific type of kidney cancer. We showed that these cells have the same genetic background as the original tumour and can be used as models to study novel treatment options for this type of kidney cancer.

TMIGD1: Emerging functions of a tumor supressor and adhesion receptor

The development of multicellular organisms depends on cell adhesion molecules (CAMs) that connect cells to build tissues. The immunoglobulin superfamily (IgSF) constitutes one of the largest families of CAMs. Members of this family regulate such diverse processes like synapse formation, spermatogenesis, leukocyte-endothelial interactions, or epithelial cell-cell adhesion. Through their extracellular domains, they undergo homophilic and heterophilic interactions in cis and trans. Their cytoplasmic domains frequently bind scaffolding proteins to assemble signaling complexes. Transmembrane and immunoglobulin domain-containing protein 1 (TMIGD1) is a IgSF member with two Ig-like domains and a short cytoplasmic tail that contains a PDZ domain-binding motif. Recent observations indicate that TMIGD1 has pleiotropic functions in epithelial cells and has a critical role in suppressing malignant cell behavior. Here, we review the molecular characteristics of TMIGD1, its interaction with cytoplasmic scaffolding proteins, the regulation of its expression, and its downregulation in colorectal and renal cancers.

A New Treatment Landscape for RCC: Association of the Human Microbiome with Improved Outcomes in RCC

Microbes play different roles in metabolism, local or systemic inflammation, and immunity, and the human microbiome in tumor microenvironment (TME) is important for modulating the response to immunotherapy in cancer patients. Renal cell carcinoma (RCC) is an immunogenic tumor, and immunotherapy is the backbone of its treatment. Correlations between the microbiome and responsiveness to immune checkpoint inhibitors have been reported. This review summarizes the recent therapeutic strategies for RCC and the effects of TME on the systemic therapy of RCC. The current understanding and advances in microbiome research and the relationship between the microbiome and the response to immunotherapy for RCC are also discussed. Improving our understanding of the role of the microbiome in RCC treatment will facilitate the development of microbiome targeting therapies to modify the tumor microbiome and improve treatment outcomes.

Identification of Prognostic and Predictive Biomarkers and Druggable Targets among 205 Antioxidant Genes in 21 Different Tumor Types via Data-Mining

(1) Background: Oxidative stress is crucial in carcinogenesis and the response of tumors to treatment. Antioxidant genes are important determinants of resistance to chemotherapy and radiotherapy. We hypothesized that genes involved in the oxidative stress response may be valuable as prognostic biomarkers for the survival of cancer patients and as druggable targets. (2) Methods: We mined the KM Plotter and TCGA Timer2.0 Cistrome databases and investigated 205 antioxidant genes in 21 different tumor types within the context of this investigation. (3) Results: Of 4347 calculations with Kaplan-Meier statistics, 84 revealed statistically significant correlations between high gene expression and worse overall survival (p < 0.05; false discovery rate ≤ 5%). The tumor types for which antioxidant gene expression was most frequently correlated with worse overall survival were renal clear cell carcinoma, renal papillary cell carcinoma, and hepatocellular carcinoma. Seventeen genes were clearly overexpressed in tumors compared to their corresponding normal tissues (p < 0.001), possibly qualifying them as druggable targets (i.e., ALOX5, ALOX5AP, EPHX4, G6PD, GLRX3, GSS, PDIA4, PDIA6, PRDX1, SELENOH, SELENON, STIP1, TXNDC9, TXNDC12, TXNL1, TXNL4A, and TXNRD1). (4) Conclusions: We concluded that a sub-set of antioxidant genes might serve as prognostic biomarkers for overall survival and as druggable targets. Renal and liver tumors may be the most suitable entities for this approach.

Cancer subtyping with heterogeneous multi-omics data via hierarchical multi-kernel learning

Differentiating cancer subtypes is crucial to guide personalized treatment and improve the prognosis for patients. Integrating multi-omics data can offer a comprehensive landscape of cancer biological process and provide promising ways for cancer diagnosis and treatment. Taking the heterogeneity of different omics data types into account, we propose a hierarchical multi-kernel learning (hMKL) approach, a novel cancer molecular subtyping method to identify cancer subtypes by adopting a two-stage kernel learning strategy. In stage 1, we obtain a composite kernel borrowing the cancer integration via multi-kernel learning (CIMLR) idea by optimizing the kernel parameters for individual omics data type. In stage 2, we obtain a final fused kernel through a weighted linear combination of individual kernels learned from stage 1 using an unsupervised multiple kernel learning method. Based on the final fusion kernel, k-means clustering is applied to identify cancer subtypes. Simulation studies show that hMKL outperforms the one-stage CIMLR method when there is data heterogeneity. hMKL can estimate the number of clusters correctly, which is the key challenge in subtyping. Application to two real data sets shows that hMKL identified meaningful subtypes and key cancer-associated biomarkers. The proposed method provides a novel toolkit for heterogeneous multi-omics data integration and cancer subtypes identification.

Epithelial-mesenchymal transition in cancer stemness and heterogeneity: updated

Epithelial-mesenchymal transition (EMT) as a trans-differentiation program and a key process in tumor progression is linked positively with increased expansion of cancer stem cells and cells with stem-like properties. This is mediated through modulation of critical tumorigenic events and is positively correlated with hypoxic conditions in tumor microenvironment. The presence of cells eliciting diverse phenotypical states inside tumor is representative of heterogeneity and higher tumor resistance to therapy. In this review, we aimed to discuss about the current understanding toward EMT, stemness, and heterogeneity in tumors of solid organs, their contribution to the key tumorigenic events along with major signaling pathway involved, and, finally, to suggest some strategies to target these critical events.

Papillary renal cell carcinoma: current and controversial issues

PURPOSE OF THE REVIEW

Papillary renal cell carcinoma (pRCC) is the second most frequent renal cancer subtype and represents 15-20% of all RCC. Classification of pRCC is changing because novel tumour entities have been discovered in the last years. In this review, we summarise recent studies relevant for the understanding of the molecular complexity and the broader differential diagnosis of pRCC.

RECENT FINDINGS

It has been 25 years ago, that pRCC was morphologically subdivided into type 1 and type 2. Recently described tumour entities in the 2022 WHO classification challenged this concept and allow a new view on the molecular background in pRCC. Biphasic hyalinizing psammomatous RCC and papillary renal neoplasm with reversed polarity are emerging tumour entities derived from the new concept of molecularly defined RCC subtypes. Immune checkpoint inhibition and tyrosine kinase inhibitors have been introduced as the new backbone in the first-line treatment of advanced pRCCs. To identify novel targeted treatments for patients with pRCC it is crucial to investigate the specific molecular background of pRCC considering emerging pRCC subtypes.

SUMMARY

In the future, a deeper understanding of the correlation between molecular aberrations and new pRCC subtypes may improve the classification of pRCC patients and could reveal potential predictive biomarkers for each subgroup.

Nanomedicine for urologic cancers: diagnosis and management

Urologic cancers accounted for more than 2 million new cases and around 0.8 million deaths in 2020. Although surgery, chemotherapy, and radiotherapy, as well as castration for prostate cancer, remain the cornerstones for managing urologic neoplasms, they can result in severe adverse effects, poor patient compliance, and unsatisfactory survival rates, thus, it is essential to develop novel options that enable the early detection of these malignancies, together with providing accurate diagnoses, and more efficient treatment strategies. Nanomedicine represents an emerging approach that can deliver formulations or drugs across traditional biological barriers in the body and be directed to specific cell types within target organs via active targeting or passive targeting, thus, showing potential to improve the management of urologic cancers. In this review, we discussed the most recent updates on the application of nanomedicines in the diagnosis and treatment of urologic cancers, with focus on prostate, bladder and kidney tumors. We also presented the anti-tumor molecular mechanisms of newly designed nanomedicine for treating urologic cancers, mainly including image-guided surgery, chemotherapy, radiotherapy, gene therapy, immunotherapy, and their synergetic therapy. Current studies have demonstrated the potential advantages of nanomedicine over conventional approaches. However, most developments and new findings in this area have not been validated in clinical trials yet, and therefore, efforts shall be made to translate these research insights into clinical practices for urologic cancers.

Essential m6A Methylation Regulator HNRNPC Serves as a Targetable Biomarker for Papillary Renal Cell Carcinoma

m6A RNA modification is a common abundant posttranscriptional modification of mRNAs occurring in cancer growth and progression. Accumulated evidence has proved that HNRNPC, which acts as a m6A reader, plays an essential role in the promotion of cancer occurrence and development; nevertheless, the role of HNRNPC in papillary renal cell carcinoma remained to be discovered. In this study, we comprehensively identified HNRNPC as a hub gene involved in m6A modification in pRCC. Then, the expression level, survival outcomes, PPI network, function enrichment, immune cell infiltration, and single-cell analysis were performed. Finally, we found that HNRNPC significantly promoted renal cell carcinoma proliferation and migration in vitro. In conclusion, our work proved that HNRNPC may act as a momentous m6A regulator, as well as a potential targetable biomarker for pRCC.

Dissection of PD-L1 promoter reveals differential transcriptional regulation of PD-L1 in VHL mutant clear cell renal cell carcinoma

Programmed death-ligand 1 (PD-L1) is constitutively expressed by hypoxia-inducible factor 2α (HIF2α). It can be induced by interferon gamma (IFNγ) signaling in clear cell renal cell carcinoma (ccRCC). Clinical trials of metastatic ccRCCs have suggested that a canonical IFNγ signature is a better biomarker for therapeutic response to immune checkpoint inhibitors (ICIs) than PD-L1 expression levels in tumor cells. To understand the therapeutic response to ICIs according to PD-L1 expression levels, we analyzed transcriptional regulation of the PD-L1 promoter by HIF2α and IFNγ-inducible interferon regulatory factor-1 (IRF-1) in ccRCC cells. Here, we present two ccRCC cell models showing differential PD-L1 expression levels in response to IFNγ and hypoxia. Analysis of The Cancer Genome Atlas RNA-sequencing data revealed that PD-L1 expression correlated with JAK2 and STAT1 expression of the canonical IFNγ signature in ccRCC tissues. Upon IFNγ stimulation, PD-L1 was induced by sequential activation of JAK2/STAT1/IRF-1 signaling in both WT- and Mut- VHL ccRCC cells. IFNγ activated the IRF-1α site of the PD-L1 promoter. The IFNγ-mediated increase of PD-L1 expression in Mut-VHL cells was 4.8-fold greater than that in WT-VHL cells. Under normoxia condition, PD-L1 expression in Mut-VHL cells was significantly higher than that in WT-VHL cells due to high basal HIF2α expression. Under hypoxia condition, PD-L1 expression in WT-VHL cells was induced up to 1.8-fold through activation of hypoxia-response elements 2 and 3. In contrast, although PD-L1 in Mut-VHL cells was already highly expressed in the basal state through activation of hypoxia-response elements 2, 3, and 4, it was no longer induced by hypoxia. In conclusion, Mut-VHL ccRCC cells displayed higher PD-L1 expression due to high basal HIF2α expression and a stronger response to IFNγ stimulation than WT-VHL cells. The fact that HIF2α antagonists can potentially reduce PD-L1 expression levels should be considered in ICI combination therapy.

Fumarate inhibits PTEN to promote tumorigenesis and therapeutic resistance of type2 papillary renal cell carcinoma

Fumarate is an oncometabolite. However, the mechanism underlying fumarate-exerted tumorigenesis remains unclear. Here, utilizing human type2 papillary renal cell carcinoma (PRCC2) as a model, we show that fumarate accumulates in cells deficient in fumarate hydratase (FH) and inhibits PTEN to activate PI3K/AKT signaling. Mechanistically, fumarate directly reacts with PTEN at cysteine 211 (C211) to form S-(2-succino)-cysteine. Succinated C211 occludes tethering of PTEN with the cellular membrane, thereby diminishing its inhibitory effect on the PI3K/AKT pathway. Functionally, re-expressing wild-type FH or PTEN C211S phenocopies an AKT inhibitor in suppressing tumor growth and sensitizing PRCC2 to sunitinib. Analysis of clinical specimens indicates that PTEN C211 succination levels are positively correlated with AKT activation in PRCC2. Collectively, these findings elucidate a non-metabolic, oncogenic role of fumarate in PRCC2 via direct post-translational modification of PTEN and further reveal potential stratification strategies for patients with FH loss by combinatorial AKTi and sunitinib therapy.

Chitosan-derived nanoparticles impede signal transduction in T790M lung cancer therapy

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) treated patients ultimately develop disease progression, about 50% of which are involved in the emergence of a p.Thr790Met (T790M) mutation acquiring drug resistance. In order to solve the aforementioned problem, a therapeutic nanoparticles DGA is developed to overcome EGFR-T790M resistance via downstream anti-apoptotic signal transduction blocking by a combination with persuading mitochondrial dysfunction and inhibiting miRNA expression. As the concept of design, chitosan-derived nanocarrier DCAFP, capable of persuading mitochondrial dysfunction, is demonstrated to convey gefitinib (GFT) and miR21 inhibitor (anti-miR21) to form DGA nanoparticles. The superior accumulation of antitumor therapeutics and synergistic blocking of downstream signal transduction by mitochondrial dysfunction and miRNA regulation lead to high sensitivity of DGA nanoparticles to EGFR-T790M mutated non-small cell lung cancer (NSCLC) cells with significant inhibition of tumor cell growth. The in vivo study demonstrates superior safety and antitumor efficacy of EGFR^T790M mutated lung cancer mouse models. These results highlight the promise of DGA nanoparticles for enhancing GFT sensitivity to EGFR^T790M NSCLC.

The significance of SMARCB1 in the pathogenesis of renal cell carcinoma with rhabdoid features

BACKGROUND

Renal cell carcinoma with rhabdoid features (RCC-RF) is an aggressive histologic variant in the adults and is usually unresponsive to standard chemotherapy.

METHODS

Expression of SMARCB1/INI1 was examined in primary RCC-RF (n = 5). Stable INI1 with/without prostaglandin E2 receptor 1 (EP1) knockdown cell lines were created in the ACHN and 786-O RCC cell lines and measured for epidermal growth factor receptor (EGFR)-related signaling pathways. Chemosensitivity to targeted drugs in vitro was tested after knocking down of INI1 in both cell lines. The outcome of co-targeting of INI1 and EP1 in RCC was examined using a tumorigenicity assay.

RESULTS

Expression of INI1 was markedly reduced at both transcriptional and translational levels in primary RCC-RF. Immunohistochemical expression of INI1 protein was lost in the nuclei of rhabdoid cells compared with conventional RCC (n = 8). Using two cell lines with different genetic background, we showed that knocking down of INI1 activates the EGFR signaling with up-regulated AKT and ERK pathways and sensitizes cancer cells to Erlotinib treatment in vitro. However, cell-line dependent effects were also demonstrated with reference to impact of INI1 or EP1 on cell growth, migration and response to Gefitinib or Everolimus treatment in vitro.

CONCLUSION

Inactivation of INI1 may play a role in the pathogenesis of RCC-RF. Erlotinib is recommended in the management of patients with INI1-related RCC.

The current knowledge concerning solid cancer and therapy

Solid cancers comprise a large number of new cases and deaths from cancer each year globally. There are a number of strategies for addressing tumors raised from solid organs including surgery, chemotherapy, radiotherapy, targeted therapy, immunotherapy, combinational therapy, and stem cell and extracellular vesicle (EV) therapy. Surgery, radiotherapy, and chemotherapy are the dominant cures, but are not always effective, in which even in a localized tumor there is a possibility of tumor relapse after surgical resection. Over half of the cancer patients will receive radiotherapy as a part of their therapeutic schedule. Radiotherapy can cause an abscopal response for boosting the activity of the immune system outside the local field of radiation, but it may also cause an unwanted bystander effect, predisposing nonradiated cells into carcinogenesis. In the context of immunotherapy, immune checkpoint inhibition is known as the standard-of-care, but the major concern is in regard with cold cancers that show low responses to such therapy. Stem-cell therapy can be used to send prodrugs toward the tumor area; this strategy, however, has its own predicaments, such as unwanted attraction toward the other sites including healthy tissues and its instability. A substitute to such therapy and quite a novel strategy is to use EVs, by virtue of their stability and potential to cross biological barriers and long-term storage of contents. Combination therapy is the current focus. Despite advances in the field, there are still unmet concerns in the area of effective cancer therapy, raising challenges and opportunities for future investigations.

Repurposing ketoconazole as an exosome directed adjunct to sunitinib in treating renal cell carcinoma

Renal Cell Carcinoma (RCC) is the most common form of kidney cancer, with clear cell RCC (ccRCC) representing about 85% of all RCC tumors. There are limited curable treatments available for metastatic ccRCC because this disease is unresponsive to conventional targeted systemic pharmacotherapy. Exosomes (Exo) are small extracellular vesicles (EVs) secreted from cancer cells with marked roles in tumoral signaling and pharmacological resistance. Ketoconazole (KTZ) is an FDA approved anti-fungal medication which has been shown to suppress exosome biogenesis and secretion, yet its role in ccRCC has not been identified. A time-course, dose-dependent analysis revealed that KTZ selectively decreased secreted Exo in tumoral cell lines. Augmented Exo secretion was further evident by decreased expression of Exo biogenesis (Alix and nSMase) and secretion (Rab27a) markers. Interestingly, KTZ-mediated inhibition of Exo biogenesis was coupled with inhibition of ERK1/2 activation. Next, selective inhibitors were employed and showed ERK signaling had a direct role in mediating KTZ's inhibition of exosomes. In sunitinib resistant 786-O cells lines, the addition of KTZ potentiates the efficacy of sunitinib by causing Exo inhibition, decreased tumor proliferation, and diminished clonogenic ability of RCC cells. Our findings suggest that KTZ should be explored as an adjunct to current RCC therapies.

Gαi1 Promoted Proliferation, Migration and Invasion via Activating the Akt-mTOR/Erk-MAPK Signaling Pathway in Renal Cell Carcinoma

Background

Renal cell carcinoma (RCC) accounts for about 2-3% of all adult malignancies. G protein alpha inhibitory subunit 1 (Gαi1) plays a key role in mediating PI3K-Akt signaling upon activation of receptor tyrosine kinases (RTKs). However, little is known about its expression, regulation and biological function in RCC.

Methods

Gαi1 expression in RCC tissues and cells was detected by quantitative real-time PCR (qRT-PCR), Western blot and immunohistochemistry (IHC). The effect of Gαi1 silence on cell proliferation and apoptosis of 786-O and ACHN cells was detected by CCK-8 assay and flow cytometry. Wound-healing assay and Transwell assays were used to detect the cell invasion in RCC cells. The expression of CDK4, cyclin D1, MMP-2, MMP-9, Bax, Bcl-2, p/t-Akt, p/t-S6 and p/t-Erk was detected by Western blot and qRT-PCR. Furthermore, a nude mouse subcutaneous xenograft model was used to further evaluate the potential effects of Gail in vivo.

Results

In the present study, our data showed that Gαi1 expression was dramatically increased in RCC tissues compared with normal renal tissues. In addition, knocking down the expression of Gαi1 subsequently inhibited proliferation, migration and invasion of RCC cells in vivo and vitro. Furthermore, the expression of CDK4, cyclin D1, MMP-2 and MMP-9 was significantly reduced upon Gαi1 inhibition. Gαi1 positively regulates the activation of the mTOR and Erk pathways.

Conclusion

In conclusion, this study reveals Gαi1 promoted proliferation via activating the Akt-mTOR and Erk-MAPK signaling pathways in RCC, and Gαi1 may be a therapeutic and prognostic target for RCC.

Angiogenesis as a hallmark of solid tumors - clinical perspectives

BACKGROUND

Angiogenesis is a key and early step in tumorigenesis, and is known as a hallmark of solid tumors and a key promoter of tumor recurrence. Unlike normal tissue vessels, the architecture of the tumor vasculature is abnormal, being leaky, tortuous, fragile and blind-ended. Perivascular cells are either detached or absent, causing reduction of vascular integrity, an increase in vessel immaturity, incoherent perfusion, defective functionality and enhanced tumor dissemination and metastasis. The abnormal tumor vasculature along with the defective tumor vessel functionality finally causes bouts of hypoxia and acidity in the tumor microenvironment (TME), further reinvigorating tumor aggression. Interstitial hypertension or high interstitial fluid pressure (IFP) is an outcome of tumor hyper-permeability. High IFP can be a barrier for either effective delivery of anti-cancer drugs toward the TME or accumulation of drugs within the tumor area, thus promoting tumor resistance to therapy. Some tumors do, however, not undergo angiogenesis but instead undergo vessel co-option or vascular mimicry, thereby adding another layer of complexity to cancer development and therapy.

CONCLUSIONS

Combination of anti-angiogenesis therapy with chemotherapy and particularly with immune checkpoint inhibitors (ICIs) is a promising strategy for a number of advanced cancers. Among the various approaches for targeting tumor angiogenesis, vascular normalization is considered as the most desired method, which allows effective penetration of chemotherapeutics into the tumor area, thus being an appropriate adjuvant to other cancer modalities.

Epigenome screening highlights that JMJD6 confers an epigenetic vulnerability and mediates sunitinib sensitivity in renal cell carcinoma

Aberrant epigenetic reprogramming represents a hallmark of renal cell carcinoma (RCC) tumorigenesis and progression. Whether there existed other epigenetic vulnerabilities that could serve as therapeutic targets remained unclear and promising. Here, we combined the clustered regularly interspaced short palindromic repeats functional screening results and multiple RCC datasets to identify JMJD6 as the potent target in RCC. JMJD6 expression correlated with poor survival outcomes of RCC patients and promoted RCC progression in vitro and in vivo. Mechanistically, aberrant p300 led to high JMJD6 expression, which activated a series of oncogenic crosstalk. Particularly, high-throughput sequencing data revealed that JMJD6 could assemble super-enhancers to drive a list of identity genes in kidney cancer, including VEGFA, β-catenin, and SRC. Moreover, this JMJD6-mediated oncogenic effect could be suppressed by a novel JMJD6 inhibitor (SKLB325), which was further demonstrated in RCC cells, patient-derived organoid models, and in vivo. Given the probable overlapped crosstalk between JMJD6 signature and tyrosine kinase inhibitors downstream targets, targeting JMJD6 sensitized RCC to sunitinib and was synergistic when they were combined together. Collectively, this study indicated that targeting JMJD6 was an effective approach to treat RCC patients.

Calcitriol inhibits migration and invasion of renal cell carcinoma cells by suppressing Smad2/3-, STAT3- and β-catenin-mediated epithelial-mesenchymal transition

Low vitamin D status is associated with progression in patients with renal cell carcinoma (RCC). The present study found that vimentin, a mesenchymal marker, was accordingly upregulated, and E-cadherin, an epithelial marker, was downregulated in RCC patients with low vitamin D status. Thus, we investigated the effects of calcitriol or vitamin D3, an active form of vitamin D, on epithelial-mesenchymal transition (EMT) in RCC cells. RCC cells were treated by two models. In model 1, three RCC cell lines, ACHN, 786-O and CAKI-2, were incubated with either LPS (2.0 μg/mL) or transforming growth factor (TGF)-β1 (10 ng/mL) in the presence or absence of calcitriol (200 nmol/L). In model 2, two RCC cell lines, ACHN and CAKI-2, were incubated with calcitriol (200 nmol/L) only. Calcitriol inhibited migration and invasion not only in TGF-β1-stimulated but also in TGF-β1-unstimulated RCC cells. Moreover, calcitriol suppressed E-cadherin downregulation and vimentin upregulation not only in TGF-β1-stimulated but also in TGF-β1-unstimulated ACHN and CAKI-2 cells. Calcitriol attenuated LPS-induced upregulation of MMP-2, MMP-7, MMP-9, MMP-26 and urokinase-type plasminogen activator (u-PA) in ACHN cells. In addition, calcitriol blocked TGF-β1-induced nuclear translocation of ZEB1, Snail and Twist1 in ACHN and CAKI-2 cells. Mechanistically, calcitriol suppressed EMT through different signaling pathways: (i) calcitriol suppressed Smad2/3 phosphorylation by reinforcing physical interaction between vitamin D receptor (VDR) and Smad3 in TGF-β1-stimulated RCC cells; (ii) calcitriol inhibited signal transducer and activator of transcription (STAT)3 activation in LPS-stimulated RCC cells; (iii) calcitriol inhibited β-catenin/TCF-4 activation by promoting integration of VDR with β-catenin in TGF-β1-unstimulated RCC cells. Taken together, calcitriol inhibits migration and invasion of RCC cells partially by suppressing Smad2/3-, STAT3- and β-catenin-mediated EMT.