[Mechanism of nuclear protein 1 in the resistance to axitinib in clear cell renal cell carcinoma].

OBJECTIVE: To explore the potential mechanism of resistance to axitinib in clear cell renal cell carcinoma (ccRCC), with a view to expanding the understanding of axitinib resistance, facilitating the design of more specific treatment options, and improving the treatment effectiveness and survival prognosis of patients. METHODS: By exploring the half maximum inhibitory concentration (IC50) of axitinib on ccRCC cell lines 786-O and Caki-1, cell lines resistant to axitinib were constructed by repeatedly stimulated with axitinib at this concentration for 30 cycles in vitro. Cell lines that were not treated by axitinib were sensitive cell lines. The phenotypic differences of cell proliferation and apoptosis levels between drug resistant and sensitive lines were tested. Genes that might be involved in the drug resistance process were screened from the differentially expressed genes that were co-upregulated in the two drug resistant lines by transcriptome sequencing. The expression level of the target gene in the drug resistant lines was verified by real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot (WB). The expression differences of the target gene in ccRCC tumor tissues and adjacent tissues were analyzed in the Gene Expression Profiling Interactive Analysis (GEPIA) public database, and the impact of the target gene on the prognosis of ccRCC patients was analyzed in the Kaplan-Meier Plotter (K-M Plotter) database. After knocking down the target gene in the drug resistant lines using RNA interference by lentivirus vector, the phenotypic differences of the cell lines were tested again. WB was used to detect the levels of apoptosis-related proteins in the different treated cell lines to find molecular pathways that might lead to drug resistance. RESULTS: Cell lines 786-O-R and Caki-1-R resistant to axitinib were successfully constructed in vitro, and their IC50 were significantly higher than those of the sensitive cell lines (10.99 µmol/L, P < 0.01; 11.96 µmol/L, P < 0.01, respectively). Cell counting kit-8 (CCK-8) assay, colony formation, and 5-ethynyl-2 '-deoxyuridine (EdU) assay showed that compared with the sensitive lines, the proliferative ability of the resistant lines decreased, but apoptosis staining showed a significant decrease in the level of cell apoptosis of the resistant lines (P < 0.01). Although resistant to axitinib, the resistant lines had no obvious new replicated cells in the environment of 20 µmol/L axitinib. Nuclear protein 1 (NUPR1) gene was screened by transcriptome sequencing, and its RNA (P < 0.0001) and protein expression levels significantly increased in the resistant lines. Database analysis showed that NUPR1 was significantly overexpressed in ccRCC tumor tissue (P < 0.05); the ccRCC patients with higher expression ofNUPR1had a worse survival prognosis (P < 0.001). Apoptosis staining results showed that knockdown ofNUPR1inhibited the anti-apoptotic ability of the resistant lines to axitinib (786-O, P < 0.01; Caki-1, P < 0.05). WB results showed that knocking downNUPR1decreased the protein level of B-cell lymphoma-2 (BCL2), increased the protein level of BCL2-associated X protein (BAX), decreased the protein level of pro-caspase3, and increased the level of cleaved-caspase3 in the resistant lines after being treated with axitinib. CONCLUSION: ccRCC cell lines reduce apoptosis through theNUPR1 -BAX/ BCL2 -caspase3 pathway, which is involved in the process of resistance to axitinib.

CD44 Is Associated with Poor Prognosis of ccRCC and Facilitates ccRCC Cell Migration and Invasion through HAS1/MMP9.

BACKGROUND: In many solid tumors, CD44 has been identified as a cancer stem cell marker as well as an important molecular in cancer progression and metastasis, making it attractive for potential therapeutic applications. However, our knowledge of the biological function and mechanism of CD44 in clear cell renal cell carcinoma (ccRCC) is limited. METHODS: In this study, the expression, prognostic values and functional enrichment analysis of CD44 in ccRCC were analyzed using public databases. Quantitative real-time PCR (qRT-PCR), Western blotting, and immunohistochemical (IHC) assays were taken to detect CD44 expression in ccRCC tissues. The effects of CD44 on the proliferation, migration and invasion of ccRCC cells were investigated by gain-of-function and loss-of-function experiments. Subcutaneous models further confirmed the role of CD44 in tumor growth. The relationship between CD44, HAS1 and MMP9 was investigated to uncover the regulatory mechanism of CD44 in ccRCC. RESULTS: CD44 was significantly upregulated in ccRCC and associated with poor overall survival (OS). Based on the functional enrichment analysis and PPI network, we found that CD44 had associations with ECM interaction and focal adhesion pathway. Clinical ccRCC sample validation revealed that CD44 mRNA and protein expression were significantly increased in ccRCC tissues, and strong CD44 staining was observed in four metastatic ccRCC cases. In vitro experiments showed that CD44 overexpression promoted cell proliferation, migration and invasion. In vivo experiments also demonstrated that CD44 overexpression accelerated tumor formation in mice. Finally, we found that CD44 regulates the expression of HAS1 in ccRCC, which is essential for the secretion of MMP9 and cell migratory ability. CONCLUSION: The upregulation of CD44 mRNA and protein expressions in ccRCC is indicative of unfavorable clinical prognoses. The CD44/HAS1/MMP9 axis is believed to exert a significant influence on the regulation of ECM degradation and ccRCC metastasis.

ATAD2 promotes glycolysis and tumor progression in clear cell renal cell carcinoma by regulating the transcriptional activity of c-Myc.

Clear cell renal cell carcinoma (ccRCC) is a common malignant tumor of the urogenital tract. Given that ccRCC is often resistant to radiotherapy and traditional chemotherapy, the clinical treatment of patients with ccRCC remains a challenge. The present study found that ATAD2 was significantly upregulated in ccRCC tissues. In vitro and in vivo experiments showed that the inhibition of ATAD2 expression mitigated the aggressive phenotype of ccRCC. ATAD2 was also associated with glycolysis in ccRCC. Interestingly, we found that ATAD2 could physically interact with c-Myc and promote the expression of its downstream target gene, thereby enhancing the Warburg effect of ccRCC. Overall, our study emphasizes the role of ATAD2 in ccRCC. The targeted expression or functional regulation of ATAD2 could be a promising method to reduce the proliferation and progression of ccRCC.

L1CAM deployed perivascular tumor niche promotes vessel wall invasion of tumor thrombus and metastasis of renal cell carcinoma.

The survival of tumor cells in the bloodstream, and vasculature adhesion at metastatic sites are crucial for tumor metastasis. Perivascular invasion aids tumor cell self-renewal, survival, and formation of metastases by facilitating readily available oxygen, nutrients, and endothelial-derived paracrine factors. Renal cell carcinoma (RCC) is among the most prevalent tumors of the urinary system, and the formation of venous tumor thrombus (VTT) is a characteristic feature of RCC. We observed high expression of L1CAM in the VTT with vessel wall invasion. L1CAM promotes the adhesion, migration, and invasion ability of RCC and enhances metastasis by interacting with ITGA5, which elicits activation of signaling downstream of integrin α5ß1. L1CAM promotes ADAM17 transcription to facilitate transmembrane ectodomain cleavage and release of soluble L1CAM. In response to soluble L1CAM, vascular endothelial cells release several cytokines and chemokines. Endothelial-derived CXCL5 and its receptor CXCR2 promote the migration and intravasation of RCC toward endothelial cells suggesting that crosstalk between endothelial cells and tumor cells has a direct guiding role in driving the metastatic spread of RCC. LICAM plays a crucial role in the invasive ability of RCC, and regulation of L1CAM expression may contribute therapeutically to preventing RCC progression.

TPM2 attenuates progression of prostate cancer by blocking PDLIM7-mediated nuclear translocation of YAP1.

BACKGROUND: Prostate cancer (PCa) is a common malignant tumor of the genitourinary system. Clinical intervention in advanced PCa remains challenging. Tropomyosins 2 (TPM2) are actin-binding proteins and have been found as a biomarker candidate for certain cancers. However, no studies have explored the role of TPM2 in PCa and its regulatory mechanism. METHODS: TPM2 expression was assessed in Gene Expression Omnibus (GEO) and the Cancer Genome Atlas (TCGA) PCa patient dataset. The effect of TPM2 on PCa progression was assessed in vitro and in vivo by quantifying proliferation, migration, invasion and tumor growth assays, and the mechanism of TPM2 in PCa progression was gradually revealed by Western blotting, immunoprecipitation, and immunofluorescence staining arrays. RESULTS: TPM2 was found to be severely downregulated in tumor tissues of PCa patients compared with tumor-adjacent normal tissues. In vitro experiments revealed that TPM2 overexpression inhibited PCa cell proliferation, invasion and androgen-independent proliferation. Moreover, TPM2 overexpression inhibited the growth of subcutaneous xenograft tumors in vivo. Mechanistically, this effect was noted to be dependent on PDZ-binding motif of TPM2. TPM2 competed with YAP1 for binding to PDLIM7 through the PDZ-binding motif. The binding of TPM2 to PDLIM7 subsequently inhibited the nuclear transport function of PDLIM7 for YAP1. YAP1 sequestered in the cytoplasm phosphorylated at S127, resulting in its inactivation or degradation which in turn inhibited the expression of YAP1 downstream target genes. CONCLUSIONS: This study investigated the role of TPM2, PDLIM7, and YAP1 in PCa progression and castration resistance. TPM2 attenuates progression of PCa by blocking PDLIM7-mediated nuclear translocation of YAP1. Accordingly, targeting the expression or functional modulation of TPM2, PDLIM7, or YAP1 has the potential to be an effective therapeutic approach to reduce PCa proliferation and prevent the progression of castration-resistant prostate cancer (CRPC).

Identification of KIF23 as a Prognostic Biomarker Associated With Progression of Clear Cell Renal Cell Carcinoma.

About 3% of adult cancers are caused by renal cell carcinoma (RCC) and its pathogenesis remains elusive. Among RCC, clear cell renal cell carcinoma (ccRCC) is the predominant histological subtype. Resistance to conventional treatments leaves few treatment options for advanced ccRCC. Although the transcriptome profile of primary ccRCC has been comprehensively summarized, the transcriptome profile of metastatic ccRCC is still lacking. In this study we identified a list of metastasis-related genes and constructing a metastasis-associated prognostic gene signature. By analyzing data from GSE85258 and GSE105288 datasets, 74 genes were identified as metastasis-related genes. To construct prognostic features, we downloaded the expression data of ccRCC from the Cancer Genome Atlas (TCGA). Metastasis-associated genes were initially selected through the LASSO Cox regression analysis and 12 metastasis-related were included to construct prognostic model. Transcriptome profile, patient prognosis, and immune cell infiltration characteristics differed between low- and high-risk groups after grouping according to median risk score. Through explored the functions of differentially expressed genes (DEGs) between the two groups. Kinesin family member 23 (KIF23) was identified as a prognostic marker in ccRCC patients. Furthermore, inhibition of KIF23 expression reduced the proliferation, migration and invasion of ccRCC cells. We further demonstrated that KIF23 promote nuclear translocation of ß-catenin in ccRCC cells, which provides novel insight into the functions and molecular machinery of KIF23 in ccRCC.

Cosmc Disruption-Mediated Aberrant O-glycosylation Suppresses Breast Cancer Cell Growth via Impairment of CD44.

BACKGROUND: Breast cancer remains the most lethal malignancy in women worldwide. Aberrant O-glycosylation is closely related to many human diseases, including breast carcinoma; however, its precise role in cancer development is insufficiently understood. Cosmc is an endoplasmic reticulum-localized chaperone that regulates the O-glycosylation of proteins. Cosmc dysfunction results in inactive T-synthase and expression of truncated O-glycans such as Tn antigen. Here we investigated the impact of Cosmc disruption-mediated aberrant O-glycosylation on breast cancer cell development through in vitro and in vivo experiments. MATERIALS AND METHODS: We deleted the Cosmc gene in two breast cancer cell lines (MCF7, T47D) using the CRISPR/Cas-9 system and then measured the expression levels of Tn antigen. The proliferation of Tn-positive cells was examined by RTCA, colony formation and in vivo experiments. The effects of Cosmc deficiency on glycoprotein CD44 and MAPK pathway were also determined. RESULTS: Both in vitro and in vivo studies showed that Cosmc deficiency markedly suppressed breast cancer cell growth compared with the corresponding controls. Mechanistically, Cosmc disruption impaired the protein expression of CD44 and the associated MAPK signaling pathway; the latter plays a crucial role in cell proliferation. Reconstitution of CD44 substantially reversed the observed alterations, confirming that CD44 requires normal O-glycosylation for its proper expression and activation of the related signaling pathway. CONCLUSION: This study showed that Cosmc deficiency-mediated aberrant O-glycosylation suppressed breast cancer cell growth, which was likely mediated by the impairment of CD44 expression.

Cosmc overexpression enhances malignancies in human colon cancer.

Cosmc is known as a T-synthase-specific molecular chaperone that plays a crucial role in the process of O-glycosylation. Cosmc dysfunction leads to inactive T-synthase and results in aberrant O-glycosylation, which is associated with various tumour malignancies. However, it is unclear whether Cosmc has some other functions beyond its involvement in O-glycosylation. In this study, we aimed to investigate the functional role of Cosmc in human colorectal cancer (CRC). We first assessed the expression levels of Cosmc in human CRC specimens and then forcedly expressed Cosmc in human CRC cell lines (HCT116, SW480) to examine its impact on cellular behaviours. The mechanisms for aberrant expression of Cosmc in CRC tissues and the altered behaviours of tumour cells were explored. It showed that the mRNA and protein levels of Cosmc were markedly elevated in human CRC specimens relative to normal colorectal tissues. The occurrence of endoplasmic reticulum (ER) stress may largely contribute to the increased Cosmc expression in cancer tissue and cells. Cosmc overexpression in CRC cells significantly promoted cell migration and invasion, which could be attributed to the activation of the epithelial-mesenchymal transition (EMT) pathway rather than aberrant O-glycosylation. These data indicate that Cosmc expression was elevated in human CRC possibly caused by ER stress, which further enhanced malignancies through the activation of EMT but independently of aberrant O-glycosylation.

DCLK1 Plays a Metastatic-Promoting Role in Human Breast Cancer Cells.

BACKGROUND: Doublecortin-like kinase 1 (DCLK1) has been universally identified as a cancer stem cell (CSC) marker and is found to be overexpressed in many types of cancers including breast cancer. However, there is little data regarding the functional role of DCLK1 in breast cancer metastasis. In the present study, we sought to investigate whether and how DCLK1 plays a metastatic-promoting role in human breast cancer cells. METHODS: We used Crispr/Cas9 technology to knock out DCLK1 in breast cancer cell line BT474, which basically possesses DCLK1 at a higher level, and stably overexpressed DCLK1 in another breast cancer cell line, T47D, that basically expresses DCLK1 at a lower level. We further analyzed the alterations of metastatic characteristics and the underlying mechanisms in these cells. RESULTS: It was shown that, compared with the corresponding control cells, DCLK1 overexpression led to an increase in metastatic behaviors including enhanced migration and invasion of T47D cells. By contrast, forced depletion of DCLK1 drastically inhibited these metastatic characteristics in BT474 cells. Mechanistically, the epithelial-mesenchymal transition (EMT) program, which is critical for cancer metastasis, was prominently activated in DCLK1-overexpressing cancer cells, evidenced by a decrease in an epithelial marker ZO-1 and an enhancement in several mesenchymal markers including ZEB1 and Vimentin. In addition, DCLK1 overexpression induced the ERK MAPK pathway, which resultantly enhanced the expression of MT1-MMP that is also involved in cancer metastasis. Knockout of DCLK1 could reverse these events, further supporting a metastatic-promoting role for DCLK1. CONCLUSIONS: Collectively, our data suggested that DCLK1 overexpression may be responsible for the increased metastatic features in breast cancer cells. Targeting DCLK1 may become a therapeutic option for breast cancer metastasis.

Tn antigen promotes human colorectal cancer metastasis via H-Ras mediated epithelial-mesenchymal transition activation.

Tn antigen is a truncated O-glycan, frequently detected in colorectal cancer (CRC), but its precise role in CRC metastasis is not well addressed. Here we investigated the effects of Core 1 ß3Gal-T specific molecular chaperone (Cosmc) deletion-mediated Tn antigen exposure on CRC metastasis and its underlying mechanism. We first used CRISPR/Cas9 technology to knockout Cosmc, which is required for normal O-glycosylation, and thereby obtained Tn-positive CRC cells. We then investigated the biological consequences of Tn antigen expression in CRC. The results showed that Tn-positive cells exhibited an enhanced metastatic capability both in vitro and in vivo. A further analysis indicated that Tn antigen expression induced typical activation of epithelial-mesenchymal transition (EMT). Mechanistically, we found that H-Ras, which is known to drive EMT, was markedly up-regulated in Tn-positive cells, whereas knockdown of H-Ras suppressed Tn antigen induced activation of EMT. Furthermore, we confirmed that LS174T cells (Tn-positive) transfected with wild-type Cosmc, thus expressing no Tn antigen, had down-regulation of H-Ras expression and subsequent inhibition of EMT process. In addition, analysis of 438 samples in TCGA cohort demonstrated that Cosmc expression was reversely correlated with H-Ras, underscoring the significance of Tn antigen-H-Ras signalling in CRC patients. These data demonstrated that Cosmc deletion-mediated Tn antigen exposure promotes CRC metastasis, which is possibly mediated by H-Ras-induced EMT activation.