Mechanisms of Acquired Resistance to Tyrosine Kinase Inhibitors in Clear - Cell Renal Cell Carcinoma (ccRCC)

TRIM8 restores p53 tumour suppressor function by blunting N-MYC activity in chemo-resistant tumours

Background

TRIM8 plays a key role in controlling the p53 molecular switch that sustains the transcriptional activation of cell cycle arrest genes and response to chemotherapeutic drugs. The mechanisms that regulate TRIM8, especially in cancers like clear cell Renal Cell Carcinoma (ccRCC) and colorectal cancer (CRC) where it is low expressed, are still unknown. However, recent studies suggest the potential involvement of some microRNAs belonging to miR-17-92 and its paralogous clusters, which could include TRIM8 in a more complex pathway.

Methods

We used RCC and CRC cell models for in-vitro experiments, and ccRCC patients and xenograft transplanted mice for in vivo assessments. To measure microRNAs levels we performed RT-qPCR, while steady-states of TRIM8, p53, p21 and N-MYC were quantified at protein level by Western Blotting as well as at transcript level by RT-qPCR. Luciferase reporter assays were performed to assess the interaction between TRIM8 and specific miRNAs, and the potential effects of this interaction on TRIM8 expression. Moreover, we treated our cell models with conventional chemotherapeutic drugs or tyrosine kinase inhibitors, and measured their response in terms of cell proliferation by MTT and colony suppression assays.

Results

We showed that TRIM8 is a target of miR-17-5p and miR-106b-5p, whose expression is promoted by N-MYC, and that alterations of their levels affect cell proliferation, acting on the TRIM8 transcripts stability, as confirmed in ccRCC patients and cell lines. In addition, reducing the levels of miR-17-5p/miR-106b-5p, we increased the chemo-sensitivity of RCC/CRC-derived cells to anti-tumour drugs used in the clinic. Intriguingly, this occurs, on one hand, by recovering the p53 tumour suppressor activity in a TRIM8-dependent fashion and, on the other hand, by promoting the transcription of miR-34a that turns off the oncogenic action of N-MYC. This ultimately leads to cell proliferation reduction or block, observed also in colon cancer xenografts overexpressing TRIM8.

Conclusions

In this paper we provided evidence that TRIM8 and its regulators miR-17-5p and miR-106b-5 participate to a feedback loop controlling cell proliferation through the reciprocal modulation of p53, miR-34a and N-MYC. Our experiments pointed out that this axis is pivotal in defining drug responsiveness of cancers such ccRCC and CRC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0634-7) contains supplementary material, which is available to authorized users.

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

Epithelial-to-mesenchymal transition (EMT) is a developmentally vital reversible process by which fully differentiated cells lose their epithelial features and acquire a migratory mesenchymal phenotype. EMT contributes to the metastatic potential of tumors. The expression profile and other biological properties of EMT suggest potential targets for cancer therapy, including in renal-cell carcinoma (RCC). The preclinical and clinical results have substantiated the promises that dysregulated elements leading to EMT can be a potential target in RCC patients. In this study, we illustrated the pathogenic and prognostic role of EMT in RCC. In addition, we reconstructed, by literature analysis, the different pathways implicated in the EMT process, thus supporting the rational for future EMT-directed therapeutic approaches for RCC patients.

Clinical use of cabozantinib in the treatment of advanced kidney cancer: efficacy, safety, and patient selection

Clear cell (cc) renal cell carcinoma (RCC) is the most common type of cancer found in the kidney accounting for ~90% of all kidney cancers. In 2012, there were ~337,000 new cases of RCC diagnosed worldwide with an estimated 143,000 deaths, with the highest incidence and mortality in Western countries. Despite improvements in cancer control achieved with VEGF- and mTOR-targeted therapy for RCC, progression remains virtually universal and additional therapies are needed. The pivotal results of the METEOR trial led to cabozantinib's designation as a breakthrough drug by the US Food and Drug Administration and its approval for treatment of advanced RCC in 2016. Subsequent data from the CABOSUN trial, where caboxantinib is compared with sunitinib, will provide information on the relative activity of cabozantinib as first-line therapy for ccRCC. We review the development of cabozantinib in advanced RCC and its role in the treatment landscape for advanced RCC.

Recent aspects of sunitinib therapy in patients with metastatic clear-cell renal cell carcinoma: a systematic review of the literature

Sunitinib is an orally available inhibitor of multiple tyrosine-kinase receptors approved for the treatment of advanced clear-cell renal cell carcinoma (ccRCC), a disease which has habitually had a very poor patient survival rate. Although it has become the most widely used drug for this disease, it remains not completely clear the best treatment strategy with these agent. The aim of this review is to highlight the most recent and interesting aspects of the research on treatment of advanced ccRCC with sunitinib and eventually determine alternative treatment schedule to reduce the incidence of side effects; we also wanted to review recent biomarkers able to predict response to therapy and also to point out the mechanism of acquired resistance to this drug.

Optimizing systemic therapy for metastatic renal cell carcinoma beyond the first-line setting

The introduction of molecularly targeted therapies (TTs) has transformed the management of metastatic renal cell carcinoma (mRCC). Within a relatively short period of time, systemic treatment of mRCC has evolved from a disease treated only by cytokines to a disease where TT is the cornerstone of patient management. Since the approval of sorafenib, an inhibitor of vascular endothelial growth factor receptor (VEGFR), in December 2005, 7 drugs have been introduced that have provided a high level of clinical efficacy in patients with mRCC, with a median survival of ~30 months in an unselected patient population that generally fits trials eligibility. Despite such success, advancements in therapies have reached a plateau: different combinations of targeted agents have not demonstrated additional benefit mainly owing to toxicity concerns, and some novel agents have failed to show benefit over approved drugs in clinics. In this review, we aim to focus on optimizing selection of agents in mRCC after progression on first-line TT. We also review how new drugs may transform existing guidelines and break through the current plateau reached with approved agents.

Molecular mechanism mediating cytotoxic activity of axitinib in sunitinib-resistant human renal cell carcinoma cells

PURPOSE

This study aimed to clarify the molecular mechanism mediating the cytotoxicity of axitinib, a selective inhibitor of the vascular endothelial growth factor receptor (VEGFR), in sunitinib-resistant renal cell carcinoma (RCC).

METHODS

In our previous study (Sakai et al. in BJU Int 112:E211-E220, 2013), a human RCC cell line, ACHN, resistant to sunitinib (ACHN/R), was developed from a parental cell line (ACHN/P). Differences in molecular phenotypes following treatment with sunitinib or axitinib between these two cell lines were compared.

RESULTS

ACHN/R showed an approximately fivefold higher IC50 of sunitinib than ACHN/P; however, there was no significant difference in the sensitivity to axitinib between these two cell lines. In ACHN/R, despite the lack of a difference in the phosphorylated (p)-Akt or STAT-3 expression between treatment with sunitinib and axitinib, the expression of p-p44/42 mitogen-activated protein kinase (MAPK) and p-VEGFR-2 after treatment with axitinib was markedly down-regulated compared with those after treatment with sunitinib. Furthermore, additional treatment of ACHN/R with an inhibitor of MAPK kinase significantly enhanced the cytotoxic activity of sunitinib, but not that of axitinib. In vivo growth of ACHN/R in nude mice after treatment with axitinib was significantly inhibited compared with that following treatment with sunitinib, accompanying the marked inhibition of angiogenesis.

CONCLUSIONS

Antitumor activity of axitinib in RCC cells even after the acquisition of resistance to sunitinib could be explained, at least in part, by the inactivation of p44/42 MAPK and VEGFR-2, which were persistently phosphorylated in sunitinib-resistant RCC cells under treatment with sunitinib.

Metabolic tumor burden is associated with major oncogenomic alterations and serum tumor markers in patients with resected pancreatic cancer

Pancreatic cancer is an aggressive and lethal disease with an overall 5-year survival rate of only 5%. Studies have demonstrated the ability of (18)F-fludrodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) to measure the metabolic tumor burden in patients with various tumors, including pancreatic cancer. In a previous study, we investigated the predictive significance of the metabolic tumor burden in terms of the metabolic tumor volume (MTV) and total lesion glycolysis (TLG). In this study, we analyzed the correlation between metabolic tumor burden and the status of the KRAS, TP53, CDKN2A/p16, and SMAD4/DPC4 genes. Our results showed that the metabolic tumor burden was associated with oncogenomic alterations that reflected the abnormal expression of carbohydrate metabolic enzymes (GLUT1, ALDOA and FBP1). We also identified a linear correlation between serum tumor markers and the metabolic tumor burden. To estimate the metabolic tumor burden when (18)F-FDG PET/CT is not available, we used the linear regression models to establish equations for MTV and TLG using CA19-9 and CA125 as independent variables. Our results suggest that the metabolic tumor burden, as evaluated by (18)F-FDG PET/CT or estimated by serum tumor markers, may be suitable for monitoring treatment response and disease progression of pancreatic cancer. Further research is needed to better understand why pancreatic cancer patients with abnormal expressions of TP53, CDKN2A/p16, and SMAD4/DPC4 get high metabolic tumor burden.

Renal cell carcinoma with intramyocardial metastases

Background

Cardiac metastases from renal cell carcinoma without vena caval involvement are extremely rare with a limited number of cases reported in the worldwide literature until now. Nevertheless, this rare location of metastasis may significantly influence patient treatment and prognosis. Cooperation between oncology, cardiology, and urology teams are indispensable in cases of patients suffering from intramyocardial tumors. For these individuals, treatment guidelines based on large-scale studies are unavailable and only case/case series analysis may provide clinicians with decision assistance.

Case presentation

In this paper, we report a case of a 50-year-old Caucasian male diagnosed with a 10.2 × 10.3 × 10.0 cm lower pole left renal mass in January 2002. He was subsequently treated with immunochemotherapy, tyrosine kinase inhibitors (TKIs), and mTOR inhibitors (mTORIs) - that is sunitinib, everolimus, and sorafenib. In March 2012, contrast-enhancing tumors in the left myocardium (∅22 mm) and in the interventricular septum (∅26 mm) were seen on CT. Cardiology testing was conducted and the patient was treated with pazopanib with a profound response. Overall survival since the clear cell renal cell carcinoma (ccRCC) diagnosis was 11 years 2 months and since diagnosis of multiple heart metastases was 1 year.

Conclusions

Cardiac metastases present a unique disease course in renal cell carcinoma. Cardiac metastases may remain asymptomatic, as in the case of this patient at the time of diagnosis. The most common cardiac presentation of renal cell carcinoma is hypertension, but other cardiac presentations include shortness of breath, cough, and arrhythmias. Targeted systemic therapy with tyrosine kinase inhibitors may be useful for this group of patients, but necrosis in the myocardium can result in tamponade and death. Regular cardiac magnetic resonance imaging scans are required for treatment monitoring.