p40, a Lactobacillus rhamnosus GG (LGG)-derived protein, transactivates epidermal growth factor receptor (EGFR) in intestinal epithelial cells, leading to amelioration of intestinal injury and inflammation. To elucidate mechanisms by which p40 regulates mucosal immunity to prevent inflammation, this study aimed to determine the effects and mechanisms of p40 on regulation of a proliferation-inducing ligand (APRIL) expression in intestinal epithelial cells for promoting IgA production. p40 up-regulated April gene expression and protein production in mouse small intestine epithelial (MSIE) cells, which were inhibited by blocking EGFR expression and kinase activity. Enteroids from Egfrfl/fl , but not Egfrfl/fl-Vil-Cre mice with EGFR specifically deleted in intestinal epithelial cells, exhibited increased April gene expression by p40 treatment. p40-conditioned media from MSIE cells increased B cell class switching to IgA+ cells and IgA production, which was suppressed by APRIL receptor neutralizing antibodies. Treatment of B cells with p40 did not show any effects on IgA production. p40 treatment increased April gene expression and protein production in small intestinal epithelial cells, fecal IgA levels, IgA+B220+, IgA+CD19+, and IgA+ plasma cells in lamina propria of Egfrfl/fl, but not Egfrfl/fl-Vil-Cre mice. Thus, p40 up-regulates EGFR-dependent APRIL production in intestinal epithelial cells, which may contribute to promoting IgA production.

In baseball parlance, a triple threat is a person who can run, hit and throw with aplomb. Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) is a cell surface protein that antagonises ERBB receptor signalling by downregulating receptor levels. Over 10 years ago, Hedman et al postulated that LRIG1 might be a tumour suppressor. Recently, Powell et al provided in vivo evidence substantiating that claim by demonstrating that Lrig1 loss in mice leads to spontaneously arising, highly penetrant intestinal adenomas. Interestingly, Lrig1 also marks stem cells in the gut, suggesting a potential role for Lrig1 in maintaining intestinal epithelial homeostasis. In this review, we will discuss the ability of LRIG1 to act as a triple threat: pan-ERBB negative regulator, intestinal stem cell marker and tumour suppressor. We will summarise studies of LRIG1 expression in human cancers and discuss possible related roles for LRIG2 and LRIG3.

MiR-34a acts as a tumor suppressor in various malignancies. In HNSCC, the role of miR-34a in proliferation has not been fully elaborated and the target genes are still bind. Here, we addressed that forced miR-34a expression induced cell cycle arrest and senescence. Hypoxia/HIF1α was found to negatively correlate to the expression of miR-34a in HNSCC tissues and partially reverse miR-34a-imposed cell senescence through suppressing miR-34a expression. In order to screen the possible target genes of miR-34a in HNSCC, the differential genes mediated by miR-34a were screened by mRNA microarray. There were 91 genes co-down regulated in two cell lines, which were closely associated with MAPK, ErbB and p53 pathways. Genes, including FUT1, AXL, and MAP2K1 were finally identified as the novel targets of miR-34a by qPCR and luciferase assay. These findings indicate that miR-34a plays an essential role in suppressing HNSCC growth through inducing cell cycle arrest and senescence, by targeting proliferation-associated genes.