The origin, evolution and route to metastasis of clear cell RCC

Expression of AOX1 Predicts Prognosis of Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most prevalent kidney cancer worldwide, and appropriate cancer biomarkers facilitate early diagnosis, treatment, and prognosis prediction in cancer management. However, an accurate biomarker for ccRCC is lacking. This study identified 356 differentially expressed genes in ccRCC tissues compared with normal kidney tissues by integrative analysis of eight ccRCC datasets. Enrichment analysis of the differentially expressed genes unveiled improved adaptation to hypoxia and metabolic reprogramming of the tumor cells. Aldehyde oxidase 1 (AOX1) gene was identified as a biomarker for ccRCC among all the differentially expressed genes. ccRCC tissues expressed significantly lower AOX1 than normal kidney tissues, which was further validated by immunohistochemistry at the protein level and The Cancer Genome Atlas (TCGA) data mining at the mRNA level. Higher AOX1 expression predicted better overall survival in ccRCC patients. Furthermore, AOX1 DNA copy number deletion and hypermethylation were negatively correlated with AOX1 expression, which might be the potential mechanism for its dysregulation in ccRCC. Finally, we illustrated that the effect of AOX1 as a tumor suppressor gene is not restricted to ccRCC but universally exists in many other cancer types. Hence, AOX1 may act as a potential prognostic biomarker and therapeutic target for ccRCC.

Complementary Role of 68Ga-Prostate-Specific Membrane Antigen and 18F-FDG PET/CT for Evaluation of Metastases and Treatment Response in Renal Cell Carcinoma

ABSTRACT

We present a case of clear cell renal cell carcinoma, which demonstrates complementary FDG and prostate-specific membrane antigen (PSMA) uptake on metastases in PET/CT, as an example of tumor heterogeneity. The patient had non-FDG-avid lung and bone metastases with PSMA uptake, whereas metastatic cervical and axillary lymph nodes showed vice versa, and skeletal muscle metastasis to vastus lateralis, which is an unusual region for metastasis, showed both PSMA and FDG positivity. In response assessment, mix response was detected. It seems that 68Ga-PSMA and 18F-FDG may have a complementary role in demonstration of metastasis accurately and assessment of treatment response in clear cell renal cell carcinoma.

Gene Expression Analysis of Aggressive Clinical T1 Stage Clear Cell Renal Cell Carcinoma for Identifying Potential Diagnostic and Prognostic Biomarkers

The molecular characteristics of early-stage clear cell renal cell carcinomas (ccRCCs) measuring ≤7 cm associated with poor clinical outcomes remain poorly understood. Here, we sought to validate genes associated with ccRCC progression and identify candidate genes to predict ccRCC aggressiveness. From among 1069 nephrectomies performed on patients, RNA sequencing was performed for 12 ccRCC patients with aggressive characteristics and matched pairs of 12 ccRCC patients without aggressive characteristics. Using a prospective cohort (ClinicalTrials.gov Identifier: NCT03694912), the expression levels of nine genes (PBRM1, BAP1, SETD2, KDM5C, FOXC2, CLIP4, AQP1, DDX11, and BAIAP2L1) were measured by reverse-transcription polymerase chain reaction from frozen tissues, and their relation to Fuhrman grade was investigated in 70 patients with small ccRCC (≤4 cm). In total, 251 genes were differentially expressed and presented fold changes with p-values < 0.05; moreover, 10 genes with the greatest upregulation or downregulation in aggressive ccRCC remained significant even after adjustment. We validated previously identified genes that were associated with ccRCC progression and identified new candidate genes that reflected the aggressiveness of ccRCC. Our study provides new insight into the tumor biology of ccRCC and will help stratify patients with early-stage ccRCC by molecular subtyping.

Hsa_circ_0035483 sponges hsa-miR-335 to promote the gemcitabine-resistance of human renal cancer cells by autophagy regulation

Renal clear cell carcinoma (RCC) is the most common pathological type of renal carcinoma and drug resistance often occurs. We studied the effect of hsa_circ_0035483 on gemcitabine sensitivity in RCC, and explored its regulatory effect on downstream hsa-miR-335 and Cyclin B1 (CCNB1). High-throughput sequencing was used to analyze the differentially expressed circRNA in RCC. The expressions of hsa_circ_0035483, hsa-miR-335, CCNB1, and autophagy-related proteins were detected by RT-PCR or Western blot. The target relationships were revealed by RNA pulldown assay and dual luciferase report assay. Autophagy marker LC3 was detected by immunofluorescence. Cell viability was detected by MTT assay. Hsa_circ_0035483 can facilitate gemcitabine-induced autophagy, and enhance the resistance of RCC to gemcitabine. Hsa-miR-335 is the target regulatory point of hsa_circ_0035483. In addition, hsa_circ_0035483 promotes autophagy and tumor growth and enhances gemcitabine resistance in RCC by regulating hsa-miR-335/CCNB1, and silenced hsa_circ_0035483 can enhance gemcitabine sensitivity in vivo. Hsa_circ_0035483 may be the target of gemcitabine resistance in the treatment of RCC.

Fisetin Suppresses the Proliferation and Metastasis of Renal Cell Carcinoma through Upregulation of MEK/ERK-Targeting CTSS and ADAM9

Fisetin, a natural flavonoid, is known to have anticarcinogenic effects against several cancers, but its role in mediating renal cell carcinoma (RCC) progression has not been delineated. Cell viability, cytotoxicity, and cell cycle distribution were measured using the 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and propidium iodide staining with flow cytometry. The in vitro migration and invasion assay was used to examine in vivo cell migration and invasion. Human protease antibody array analysis was conducted with cell migration/invasion-related proteins. Western blotting and quantitative reverse transcription polymerase chain reaction were used for assessing protein expression related to the cell cycle, cell invasion, and mitogen-activated protein kinase (MAPK) signaling pathway. We found that fisetin significantly inhibited cell viability through cell cycle arrest in the G2/M phase, in addition to downregulating cyclin D1 and upregulating p21/p27. Fisetin inhibited the migration and invasion of human RCC cells through the downregulation of CTSS and a disintegrin and metalloproteinase 9 (ADAM9). Fisetin also upregulated ERK phosphorylation in 786-O and Caki-1 cells. Furthermore, treatment with a MEK inhibitor (UO126) reduced the inhibitory effects of fisetin on the metastasis of RCC cells through the ERK/CTSS/ADAM9 pathway. Fisetin inhibits proliferation and metastasis of RCC cells by downregulating CTSS and ADAM9 through the MEK/ERK signaling pathway. These findings indicate that fisetin is a promising antitumor agent against RCC.