Investigating the Pathogenic Role of PADI4 in Oesophageal Cancer

Abstract

PADI4 post-translationally converts peptidylarginine to citrulline. PADI4 can disrupt the apoptotic process via the citrullination of histone H3 in the promoter of p53-target genes. The current study focused on PADI4 expression in various subtypes of oesophageal carcinoma (EC) by immunohistochemistry, western blotting and real time PCR. The study also investigated the effect of bile acid deoxycholate (DCA) on PADI4 expression in Eca-109 cells that originated from EC. Apoptosis and DCA-induced toxicity were analyzed by TUNEL, MTT assay and flow cytometry. Additionally, the present study investigated the correlation between single nucleotide polymorphism (SNP) in PADI4 gene and EC risk in Chinese population using Illumina GoldenGate assay. Compared with paraneoplastic tissues, the transcriptional and translational levels of PADI4 were significantly elevated in oesophageal squamous cell carcinoma (ESCC, n=9) and oesophageal adenocarcinoma (EAC, n=5) tissues. Immunolabeling detected expression of PADI4 in ESCC tissues (98.56%, n=139), EAC samples (87.5%, n=16) and oesophageal small cell undifferentiated carcinoma (91.7%, n=12) but not in normal tissues (0%, n=16). Furthermore, PADI4 levels is positively correlated with the pathological classification of ESCC (p=0.009). PADI4 expression levels were consistent with the number of apoptotic cells in the induced Eca-109 cells. rs10437048 [OR= 0.012831; 95% CI, 0.001746~0.094278; p=1.556×10-12] were significantly associated with decreased risk of EC, whereas rs41265997 [OR=12.7; 95% CI, 0.857077~33.207214; p=3.896×10-8] were significantly associated with increased risk of EC. rs41265997 in exon 3 of PADI4 gene is non-synonymous and converts ACG to ATG resulting in a threonine /methionine conversion at position 274 of the protein. Haplotypes GC that carries the variant alleles for rs2501796 and rs2477134 was significantly associated with increased risk of EC (frequency=0.085, p=0.0256, OR=2.7). The results suggest that PADI4 expression is related to the tumorigenic process of EC and the DCA-induced apoptosis. The PADI4 gene may be a valid EC susceptibility gene.

B-cell specific Moloney leukemia virus insert site 1 and peptidyl arginine deiminase IV positively regulate carcinogenesis and progression of esophageal squamous cell carcinoma

“…Chang et al confirmed that the expression level of PADI4 was positively associated with the pathological classification of ESCC. The previous study also identified that apoptosis corresponded to the expression of PADI4 in cultured EC cells that were treated with dichloroacetate (35). In the present study, the expression of PADI4 was significantly increased in ESCC tissues compared with the corresponding noncancerous mucosal tissues.…”

“…In addition, a number of studies proposed that PADI4 plays an important role in various cellular processes, including proliferation, the cell cycle and apoptosis (27,(30)(31)(32)(33). PADI4 overexpression has also been considered to reduce the expression of p53-targeted genes, resulting in the disruption of cellular apoptosis and of the normal cell cycle (35,43,44). Previous studies have confirmed that PADI4 disrupts the apoptotic process via citrullination of histone H3, which acts on the promoter of p53 target genes (44,45).…”

Citrullination – small change with a great consequence

“…In the pathogenesis of many diseases the reduction of appropriate level of protein citrullination was observed (psoriasis). On the other hand, the increased levels of LArg citrullination in physiological substrates (multiple sclerosis, progression of cancer) and modification of proteins that are not a physiological substrates for PAD was also presented (rheumatoid arthritis) (Vossenaar et al 2003;Chang et al 2011;Takizawa et al 2006).…”

Fluorescence-based Monitoring of PAD4 Activity via a Pro-fluorescence Substrate Analog

“…In fact, the presence of anti-citrullinated protein antibodies is one of the most reliable and definitive diagnostic and prognostic biomarkers of rheumatoid arthritis 18 . Likewise, dysregulated PAD4 activity has recently been observed in a number of human cancers including ovarian, breast, lung, and esophageal cancers [19][20][21][22] . The link between PAD4 and cancer has been shown to be mediated through the ELK1 oncogene or via the p53 tumor suppressor protein 22,23 and previous work has suggested that PAD4 could be a novel anti-cancer therapeutic target .…”

“…Likewise, dysregulated PAD4 activity has recently been observed in a number of human cancers including ovarian, breast, lung, and esophageal cancers [19][20][21][22] . The link between PAD4 and cancer has been shown to be mediated through the ELK1 oncogene or via the p53 tumor suppressor protein 22,23 and previous work has suggested that PAD4 could be a novel anti-cancer therapeutic target . Quite remarkably, PAD4 inhibition appeared to act as a targeted therapy that resulted in selective killing of cancerous cells while sparing untransformed cells.…”