Expression of apoptotic tumour necrosis factor receptor-associated factor, caspase recruitment domain and cell death-inducing DFF-45 effector genes in therapy-treated renal cell carcinoma

A double-edged sword: role of apoptosis repressor with caspase recruitment domain (ARC) in tumorigenesis and ischaemia/reperfusion (I/R) injury

Apoptosis repressor with caspase recruitment domain (ARC) acts as a potent and multifunctional inhibitor of apoptosis, which is mainly expressed in postmitotic cells, including cardiomyocytes. ARC is special for its N-terminal caspase recruitment domain and caspase recruitment domain. Due to the powerful inhibition of apoptosis, ARC is mainly reported to act as a cardioprotective factor during ischaemia‒reperfusion (I/R) injury, preventing cardiomyocytes from being devastated by various catastrophes, including oxidative stress, calcium overload, and mitochondrial dysfunction in the circulatory system. However, recent studies have found that ARC also plays a potential regulatory role in tumorigenesis especially in colorectal cancer and renal cell carcinomas, through multiple apoptosis-associated pathways, which remains to be explored in further studies. Therefore, ARC regulates the body and maintains the balance of physiological activities with its interesting duplex. This review summarizes the current research progress of ARC in the field of tumorigenesis and ischaemia/reperfusion injury, to provide overall research status and new possibilities for researchers.

Bioinformatic gene analysis for possible biomarkers and therapeutic targets of hypertension-related renal cell carcinoma

BACKGROUND

Renal cell carcinoma (RCC) is one of the most prevalent malignant tumors of the urinary system. Hypertension can cause hypertensive nephropathy (HN). Meanwhile, Hypertension is considered to be related to kidney cancer. We analyzed co-expressed genes to find out the relationship between hypertension and RCC and show possible biomarkers and novel therapeutic targets of hypertension-related RCC.

METHODS

We identified the differentially expressed genes (DEGs) of HN and RCC through analyzing Gene Expression Omnibus (GEO) datasets GSE99339, GSE99325, GSE53757 and GSE15641 by means of bioinformatics analysis, respectively. Then we evaluated these genes with protein-protein interaction (PPI) networks, Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and CTD database. Subsequently, we verified co-expressed DEGs with Gene Expression Profiling Interactive Analysis (GEPIA) database. Finally, corresponding predicted miRNAs of co-expressed DEGs were identified and verified via mirDIP database and Starbase, respectively.

RESULTS

We identified 9 co-expressed DEGs, including BCAT1, CORO1A, CRIP1, ESRRG, FN1, LYZ, PYCARD, SAP30, and PTRF. CRIP1 and ESRRG and their corresponding predicted miRNAs, especially hsa-miR-221-5p, hsa-miR-205-5p, hsa-miR-152-3p and hsa-miR-137 may be notably related to hypertension-related RCC.

CONCLUSIONS

CRIP1 and ESRRG genes have great potential to become novel biomarkers and therapeutic targets concerning hypertension-related RCC.

miR-214 Down-Regulation Promoted Hypoxia/Reoxygenation-Induced Hepatocyte Apoptosis Through TRAF1/ASK1/JNK Pathway

OBJECTIVE

This study investigated the role of miR-214 in the hepatocyte apoptosis induced by hypoxia/reoxygenation (H/R) injury.

MATERIALS AND METHODS

In vivo hepatic ischemia/reperfusion (HIR) injury, mice model and in vitro HR model were established. miR-214, TRAF1, ASK1, and JNK expression levels were detected by qRT-PCR and western blot. The apoptosis of mouse hepatocyte AML12 was detected by flow cytometry analysis. The interaction between miR-214 and TRAF1 was confirmed by dual-luciferase reporter gene assay.

RESULTS

Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were elevated in HIR injury mice compared with sham mice. miR-214 expression was down-regulated in liver tissues of HIR and H/R-induced hepatocytes, whereas TRAF1, ASK1, and JNK expressions were up-regulated in HIR and H/R groups. H/R stimulation promoted the apoptosis of hepatocytes, and miR-214 overexpression inhibited the apoptosis of hepatocytes. Besides, TRAF1 was a target of miR-214 and negatively regulated by miR-214. miR-214/TRAF1 pathway involved in the modulation of H/R-induced apoptosis of hepatocytes. In vivo study proved miR-214 reduced hepatic injury of HIR mice.

CONCLUSION

miR-214 overexpression reduces hepatocyte apoptosis after HIR injury through negatively regulating TRAF1/ASK1/JNK pathway.

TXNDC5 is a cervical tumor susceptibility gene that stimulates cell migration, vasculogenic mimicry and angiogenesis by down-regulating SERPINF1 and TRAF1 expression

TXNDC5 (thioredoxin domain-containing protein 5) catalyzes disulfide bond formation, isomerization and reduction. Studies have reported that TXNDC5 expression is increased in some tumor tissues and that its increased expression can predict a poor prognosis. However, the tumorigenic mechanism has not been well characterized. In this study, we detected a significant association between the rs408014 and rs7771314 SNPs at the TXNDC5 locus and cervical carcinoma using the Taqman genotyping method. We also detected a significantly increased expression of TXNDC5 in cervical tumor tissues using immunohistochemistry and Western blot analysis. Additionally, inhibition of TXNDC5 expression using siRNA prevented tube-like structure formation, an experimental indicator of vasculogenic mimicry and metastasis, in HeLa cervical tumor cells. Inhibiting TXNDC5 expression simultaneously led to the increased expression of SERPINF1 (serpin peptidase inhibitor, clade F) and TRAF1 (TNF receptor-associated factor 1), which have been reported to inhibit angiogenesis and metastasis as well as induce apoptosis. This finding was confirmed in Caski and C-33A cervical tumor cell lines. The ability to form tube-like structures was rescued in HeLa cells simultaneously treated with anti-TXNDC5, SERPINF1 and TRAF1 siRNAs. Furthermore, the inhibition of TXNDC5 expression significantly attenuated endothelial tube formation, a marker of angiogenesis, in human umbilical vein endothelial cells. The present study suggests that TXNDC5 is a susceptibility gene in cervical cancer, and high expression of this gene contributes to abnormal angiogenesis, vasculogenic mimicry and metastasis by down-regulating SERPINF1 and TRAF1 expression.

Tumour necrosis factor receptor-associated factor-1 (TRAF-1) expression is increased in renal cell carcinoma patient serum but decreased in cancer tissue compared with normal: potential biomarker significance

Renal cell carcinoma (RCC) generally has a poor prognosis because of late diagnosis and metastasis. We have previously described decreased tumour necrosis factor receptor-associated factor-1 (TRAF-1) in RCC compared with paired normal kidney in a patient cohort in Australia. In the present study, TRAF-1 expression in clear cell RCC (ccRCC) and normal kidney was again compared, but in a cohort from University Malaya Medical Centre. Serum TRAF-1 was also evaluated in RCC and normal samples.Immunohistochemistry with automated batch staining and Aperio ImageScope morphometry was used to compare TRAF-1 in 61 ccRCC with paired normal kidney tissue. Serum from 15 newly diagnosed and untreated ccRCC and 15 healthy people was tested for TRAF-1 using ELISA.In this cohort, TRAF-1 was highly expressed in proximal tubular epithelium of normal kidney, and significantly decreased in ccRCC tissue (p < 0.001). Conversely, TRAF-1 in serum from ccRCC patients was significantly increased over control serum (132 ± 30 versus 54 ± 14 pg/mL, respectively; p = 0.013).Decreased TRAF-1 in RCC tissue, reported previously, was confirmed. This, along with significantly increased serum TRAF-1 may indicate the protein is actively secreted during development and progression of ccRCC. Therefore, the increased serum TRAF-1 may be a useful non-invasive indicator of RCC development.

Decreased Expression of Inhibitor of Caspase-Activated DNase (ICAD) in Renal Cell Carcinoma - Tissue Microarray of Human Samples

Although primary localised tumours of renal cell carcinoma (RCC) can be treated relatively successfully with surgery, metastatic RCC has poor prognosis because of late diagnosis and resistance to therapies. In the present study, we were interested in profiling the protein expression of “inhibitor of caspase-activated DNase” (ICAD), an apoptosis inhibitor, in kidney cancer and its paired normal kidney. Immunohistochemistry with automated batch staining and morphometry using digital pathology were used to compare ICAD in 121 RCC specimens with their paired normal kidney tissue. Tissue microarray of formalin-fixed, paraffin-embedded archival tissue was used. Intensity and localisation of ICAD were compared between normal and cancer samples, and against grading within the cancers. The results demonstrated that, in this cohort, ICAD was highly expressed in the proximal tubular epithelium of normal kidney, and significantly decreased in clear cell RCC tissue (p < 0.05) as well as other subtypes of RCC (p < 0.01) compared with normal kidney. There was a tendency towards nuclear localisation of ICAD in clear cell RCC, but not in other subtypes of RCC. No significant association was found between ICAD intensity and grade of RCC. In summary, down-regulation of ICAD occurs in RCC. ICAD normally inhibits DNA fragmentation and apoptosis; thus, its down-regulation was unexpected in a cancer known for its resistance to apoptosis. However, these RCC samples were from primary, not metastatic, RCC sites, and down-regulated ICAD may be part of a progressive pathway that promotes RCC metastasis.

Patient samples of renal cell carcinoma show reduced expression of TRAF1 compared with normal kidney and functional studies in vitro indicate TRAF1 promotes apoptosis: potential for targeted therapy

AIMS

The tumour necrosis factor (TNF) receptor-associated factor (TRAF) family of proteins links the TNF receptor superfamily to cell signalling cascades. TRAF1 is involved in regulation of apoptosis, proliferation, differentiation and stress responses. It has a role in development of several malignancies, but no information for renal cell carcinoma (RCC) is available.

METHODS

Expression profiles for TRAF1 were investigated in 121 samples of human RCC of various subtypes plus paired normal kidney prepared in tissue microarrays, in comparison with apoptosis (morphology, ApopTag) and mitosis (morphology, proliferating cell nuclear antigen/PCNA). TRAF1 function was tested in vitro in RCC ACHN cells. TRAF1 short interfering RNA (siRNA) was used to inhibit expression of TRAF1 in ACHN cells untreated or treated with cancer therapies known to induce apoptosis (20 Gy X-irradiation and/or 500 IU/mL interferon-alpha).

RESULTS

In patient samples, TRAF1 localised to proximal tubular epithelium in normal kidney and was significantly decreased in clear cell RCC as one group (p < 0.01) and all other RCC subclassifications grouped together (p < 0.05). There was little apoptosis identified in any RCC samples. In vitro, TRAF1 siRNA caused significant reduction in TRAF1 expression and a concurrent decrease in apoptosis and increase in proliferative activity (both p < 0.05) in the ACHN RCC cells treated with radiation and interferon-alpha.

CONCLUSION

TRAF1 may have a pro-apoptotic, anti-mitotic role in RCC. The low TRAF1 expression in untreated RCC patient samples compared with normal kidney, and the localisation of TRAF1 to the proximal tubular epithelium from which many RCC originate, may indicate a potential for targeted therapy in RCC.

siRNA-mediated knock-down of DFF45 amplifies doxorubicin therapeutic effects in breast cancer cells

PURPOSE

RNA interference (RNAi) has become a promising tool for cancer therapy. Small interfering RNAs (siRNAs) can synergistically enhance the cell killing effects of drugs used in cancer treatment. Here we examined the effects of siRNA-mediated DNA fragmentation factor 45 (DFF45) gene silencing on breast cancer cell viability, cell cycle arrest, and apoptosis in the presence and absence of doxorubicin.

METHODS

We designed three siRNAs, which target different regions of the DFF45 mRNA. Gene silencing was confirmed by real time RT-PCR and Western blot analyses. The impact of DFF45 siRNA, doxorubicin, and their combination on the viability, cell cycle and apoptosis of T-47D and MDA-MB-231 breast cancer cells were determined by MTT, PI staining, annexin V binding, caspase-3 activity, DNA laddering, and chromatin condensation assays.

RESULTS

Based on flow cytometric analyses, we found that silencing of DFF45 alone had little effect on apoptosis, especially in T-47D cells. However, when used in combination with doxorubicin (0.33 μM) a significant increase (P < 0.05) in apoptosis was observed in T-47D and MDA-MB-231 cells, i.e., ~2.5- and 3-fold, respectively. Caspase-3 activity, chromatin condensation, as well as DNA laddering supported increased apoptosis in the combinatorial treatment. Cell cycle arrest in both cell lines occurred at lower levels after siRNA + doxorubicin treatment compared to doxorubicin only.

CONCLUSIONS

Our data indicate that DFF45 gene silencing, when applied in combination with doxorubicin, may offer a novel therapeutic strategy for the treatment of breast cancer.

MiR-145, a new regulator of the DNA fragmentation factor-45 (DFF45)-mediated apoptotic network

BACKGROUND

MicroRNA-145 (miR-145) is considered to play key roles in many cellular processes, such as proliferation, differentiation and apoptosis, by inhibiting target gene expression. DNA Fragmentation Factor-45 (DFF45) has been found to be the substrate of Caspase-3, and the cleavage of DFF45 by caspase-3 during apoptosis releases DFF40 that degrades chromosomal DNA into nucleosomal fragments. There are currently no in-depth studies on the relationship between miR-145 and the DFF45 gene.

RESULTS

In this study, we identified DFF45 as a novel target of miR-145. We demonstrated that miR-145 targets a putative binding site in the coding sequence (CDS) of DFF45, and its abundance is inversely associated with DFF45 expression in colon cancer cells. Using a luciferase reporter system, we found that miR-145 suppresses the expression of the luciferase reporter gene fused to the putative binding site of DFF45. The level of DFF45 protein, but not DFF45 mRNA, was decreased by miR-145, suggesting a mechanism of translational regulation. Furthermore, we demonstrate that this specific silencing of DFF45 by miR-145 accounts, at least in part, for the staurosporine-induced tumor cell apoptosis in vitro.

CONCLUSIONS

Our study reveals a previously unrecognized function of miR-145 in DFF45 processing, which may underlie crucial aspects of cancer biology.