Using yeast two-hybrid system to identify ECRG2 associated proteins and their possible interactions with ECRG2 gene

The oncogenic potential of Rab-like protein 1A (RBEL1A) GTPase: The first review of RBEL1A research with future research directions and challenges

Research on Rab-like protein 1A (RBEL1A) in the past two decades highlighted the oncogenic properties of this gene. Despite the emerging evidence, its importance in cancer biology was underrated. This is the first RBEL1A critical review covering its discovery, biochemistry, physiological functions, and clinical insights. RBEL1A expression at the appropriate levels appears essential in normal cells and tissues to maintain chromosomal stability; however, its overexpression is linked to tumorigenesis. Furthermore, the upstream and downstream targets of the RBEL1A signaling pathways will be discussed. Mechanistically, RBEL1A promotes cell proliferation signals by enhancing the Erk1/2, Akt, c-Myc, and CDK pathways while blunting the apoptotic signals via inhibitions on p53, Rb, and caspase pathways. More importantly, this review covers the clinical relevance of RBEL1A in the cancer field, such as drug resistance and poor overall survival rate. Also, this review points out the bottle-necks of the RBEL1A research and its future research directions. It is becoming clear that RBEL1A could potentially serve as a valuable target of anticancer therapy. Genetic and pharmacological researches are expected to facilitate the identification and development of RBEL1A inhibitors as cancer therapeutics in the future, which could undoubtedly improve the management of human malignancy.

SPINKs in Tumors: Potential Therapeutic Targets

The serine protease inhibitor Kazal type (SPINK) family includes SPINK1-14 and is the largest branch in the serine protease inhibitor family. SPINKs play an important role in pancreatic physiology and disease, sperm maturation and capacitation, Nager syndrome, inflammation and the skin barrier. Evidence shows that the unregulated expression of SPINK1, 2, 4, 5, 6, 7, and 13 is closely related to human tumors. Different SPINKs exhibit various regulatory modes in different tumors and can be used as tumor prognostic markers. This article reviews the role of SPINK1, 2, 4, 5, 6, 7, and 13 in different human cancer processes and helps to identify new cancer treatment targets.

ECRG2 enhances the anti-cancer effects of cisplatin in cisplatin-resistant esophageal cancer cells via upregulation of p53 and downregulation of PCNA

AIM

To explore the anti-tumor effects of esophageal cancer-related gene 2 (ECRG2) in combination with cisplatin (DDP) in DDP-resistant esophageal cancer cells (EC9706/DDP).

METHODS

A drug-resistant cell model was established, with EC9706/DDP cells being treated with ECRG2 and/or DDP. Cell viability was examined by MTT assay. The rate of cell apoptosis was determined by flow cytometry. The mRNA expression levels of proliferating cell nuclear antigen (PCNA), metallothionein (MT), and p53 were determined by RT-PCR and PCNA, while MT and p53 protein expression levels were determined by western blotting.

RESULTS

The anti-proliferative effect of ECRG2 in combination with DDP was superior when compared to ECRG2 or DDP alone. The inhibition rate for the combination reached its peak (51.33%) at 96 h. The early apoptotic rates of the control, ECRG2 alone, DDP alone, and ECRG2 plus DDP groups were 5.71% ± 0.27%, 12.68% ± 0.61%, 14.15% ± 0.87%, and 27.96% ± 0.36%, respectively. Although all treatment groups were significantly different from the control group (P < 0.05), the combination treatment of ECRG2 plus DDP performed significantly better when compared to either ECRG2 or DDP alone (P < 0.05). The combination of ECRG2 and DDP significantly upregulated p53 mRNA and protein levels and downregulated PCNA mRNA and protein levels compared to ECRG2 or DDP alone (P < 0.05). However, no changes were seen in the expression of MT mRNA or protein.

CONCLUSION

ECRG2 in combination with DDP can inhibit viability and induce apoptosis in esophageal cancer DDP-resistant cells, possibly via upregulation of p53 expression and downregulation of PCNA expression. These findings suggest that the combination of ECRG2 and DDP may be a promising strategy for the clinical treatment of esophageal cancers that are resistant to DDP.

RABL6A, a novel RAB-like protein, controls centrosome amplification and chromosome instability in primary fibroblasts

RABL6A (RAB-like 6 isoform A) is a novel protein that was originally identified based on its association with the Alternative Reading Frame (ARF) tumor suppressor. ARF acts through multiple p53-dependent and p53-independent pathways to prevent cancer. How RABL6A functions, to what extent it depends on ARF and p53 activity, and its importance in normal cell biology are entirely unknown. We examined the biological consequences of RABL6A silencing in primary mouse embryo fibroblasts (MEFs) that express or lack ARF, p53 or both proteins. We found that RABL6A depletion caused centrosome amplification, aneuploidy and multinucleation in MEFs regardless of ARF and p53 status. The centrosome amplification in RABL6A depleted p53−/− MEFs resulted from centrosome reduplication via Cdk2-mediated hyperphosphorylation of nucleophosmin (NPM) at threonine-199. Thus, RABL6A prevents centrosome amplification through an ARF/p53-independent mechanism that restricts NPM-T199 phosphorylation. These findings demonstrate an essential role for RABL6A in centrosome regulation and maintenance of chromosome stability in non-transformed cells, key processes that ensure genomic integrity and prevent tumorigenesis.

MicroRNA-1322 regulates ECRG2 allele specifically and acts as a potential biomarker in patients with esophageal squamous cell carcinoma

A short tandem repeat (STR) polymorphism in the 3'UTR region of esophageal cancer-related gene 2 (ECRG2, also known as SPINK7) has been widely reported to be associated with the incidence and the prognosis of esophageal squamous cell carcinoma (ESCC). This study explores how the microRNA binding to the STR region affects ECRG2 expression in ESCC. Dual-luciferase reporter assays were used to verify the effects of the four microRNAs (miR-580, miR-1182, miR-1272, and miR-1322) predicted to bind the STR region of the ECRG2 3' untranslated region (UTR). The expression of identified effective microRNA was then analyzed in 44 paired ESCC and adjacent normal tissues and 402 case-controlled serum samples (divided into a discovery group and an independent validation group) by real-time RT-PCR assay. We found that only miR-1322 could significantly down-regulate the ECRG2 with TCA3 allele (P < 0.01), but it could not down-regulate the ECRG2 with TCA4 allele significantly (P > 0.05). MiR-1322 was also expressed significantly higher in ESCC tissue and serum samples than in controls (both P < 0.01). Additionally, serum levels of miR-1322 yielded an under receiver operating characteristic (ROC) curve area of 0.847 (95% CI, 0.795-0.890) for discriminating ESCCs from healthy controls in the discovery group and a similar result was obtained in the validation group (under ROC area is 0.845; 95%CI, 0.780-0.897). We conclude that miR-1322 can regulate ECRG2 in an allele-specific manner and that serum levels of miR-1322 can serve as a potential diagnostic biomarker for patients with ESCC.

Short tandem repeat polymorphism in exon 4 of esophageal cancer-related gene 2 detected in genomic DNA is a prognostic marker for esophageal cancer

BACKGROUND

Short tandem repeat (STR) polymorphisms in exon 4 of the esophageal cancer-related gene 2 (ECRG2) are a risk marker for esophageal carcinoma. The aim of the present study was to correlate these STRs with clinical outcome.

METHODS

Genomic DNA of 86 patients who underwent complete surgical resection was analyzed for STRs TCA3/TCA3, TCA3/TCA4, and TCA4/TCA4 in exon 4 of ECRG2 by polymerase chain reaction and DNA sequencing.

RESULTS

ECRG2 STR TCA3/TCA3 and TCA3/TCA4 were found in 40 (47%) patients, respectively, and TCA4/TCA4 in 6 (7%) cases. TCA3/TCA3 genotype was significantly associated with reduced survival (P < .05, log-rank test). TCA3/TCA3 STR was the strongest prognostic factor determined by multivariate Cox regression analysis.

CONCLUSIONS

Genetically fixed STR polymorphism TCA3/TCA3 in exon 4 of ECRG2 is associated with poor clinical outcome in surgically treated esophageal cancer patients and might be a potential prognostic marker. The usefulness of these genetic markers to predict responsiveness toward neoadjuvant treatment of esophageal cancer patients would be of high clinical interest and should be examined in future studies.

Short tandem repeat polymorphism in exon 4 of esophageal cancer related gene 2 predicts relapse of oral squamous cell carcinoma

Short tandem repeat (STR) polymorphisms in exon 4 of esophageal cancer related gene 2 (ECRG2) are a prognostic marker for squamous cell carcinoma (SCC) of the esophagus. The aim of the present study was to correlate these STRs with clinical outcome of the similar tumor type oral squamous cell carcinoma (OSCC). DNA of 81 patients that underwent complete surgical resection of OSCC was analyzed for STRs TCA3/TCA3, TCA3/TCA4 and TCA4/TCA4 in exon 4 of ECRG2 by PCR, capillary electrophoresis and DNA sequencing. ECRG2 STR TCA3/TCA3 were found in 45 (56%), TCA3/TCA4 in 33 (41%) and TCA4/TCA4 in 3 (3%) patients. TCA3/TCA3 was significantly associated with reduced relapse-free survival of OSCC, compared with TCA3/TCA4 and TCA4/TCA4 genotypes (P<0.05; log-rank test). TCA3/TCA3 STR was independent prognostic factor determined by multivariate Cox regression analysis (p<0.05). STR polymorphism TCA3/TCA3 in exon 4 of ECRG2 is associated with poor relapse-free survival in surgically completely resected OSCC patients and might be a potential prognostic marker.

Monoclonal Antibodies to Esophageal Cancer–Related Gene2 Protein

Esophageal cancer related gene2 (ECRG2) acts as a bi-functional gene associated with regulation of cell growth and death, and plays an important role in carcinogenesis of esophageal cancer. RT-PCR and Northern blot data showed that ECRG2 was expressed in normal esophagus, liver, colon, and lung tissues, but lost or greatly down-regulated in the adjacent and cancerous tissues, especially in esophageal cancer. However, studies of protein have been hampered by the lack of a sensitive and specific antibody. Here, we generated anti-ECRG2 monoclonal antibodies (MAbs) by using c-terminal of ECRG2 peptide as immunogen. Antibodies 8C9c53, 5E3c9, and 3C5c76, are suitable for detecting the ECRG2 on ELISA and Western blot assays, and 1E4c2 and 4B6c41 are suitable for immunofluorescence microscopy. The study also provides novel data about ECRG2 protein expression in the cytoplasm and the possibility of post-translation modification in mammalian cells. Based on these findings, it may be expected that anti-ECRG2 monoclonal antibodies will be valuable tools for research and diagnosis.

Differential expression and bioinformatics analysis of SLP-2 gene in esophageal squamous cell carcinoma

AIM: One of the differentially expressed genes, SLP-2 (stomatin-like protein 2, SLP-2), was obtained from esophageal squamous cell carcinoma (ESCC) patient-matched tissues using cDNA microarrays, which was overexpressed in ESCC tissues compared with their normal counterparts. This study was to confirm overexpression of SLP-2 in ESCC, to construct tissue expression pattern of SLP-2 in different embryonic tissues and to carry out bioinformatics analysis.

METHODS: Overexpression of SLP-2 in esophageal squamous cell carcinoma was confirmed by RT-PCR and Northern blot. Tissue expression pattern was constructed by RT-PCR. And the biological property was analyzed by bioinformatic softwares.

RESULTS: RT-PCR and Northern blot showed that SLP-2 was overexpressed in ESCC tissues and distributed in different embryonic tissues. Relatedness between members of the stomatin superfamily was compared using CLUSTAL procedure. Simple Modular Architecture Research Tool (SMART) software predicted that it possessed a PHB domain (prohibitin homologue) and a coiled coil.

CONCLUSION: cDNA microarray is a powerful tool for screening differentially expressed genes. SLP-2 is overex-pressed in ESCC tissues and expressed in different embryonic tissues. The biological property is analyzed by bioinformatic softwares. Our study lays a good foundation for elucidation the molecular mechanism of initiation and progression of ESCC.