Immunohistochemical Profile of Tumor Suppressor Proteins RASSF1A and LATS1/2 in Relation to p73 and YAP Expression, of Human Inflammatory Bowel Disease and Normal Intestine

RASFF1A inhibits the epithelial-mesenchymal transition of lens epithelial cells induced by TGFβ through regulating HDAC6

To explore the role of Ras-association domain family 1 A (RASSF1A) in TGFβ2-induced changes of lens epithelial cells (LECs) behavior. The human LEC line SRA01/04 cells were treated with TGFβ2 in the presence or absence of RASSF1A and histone deacetylase 6 (HDAC6). qRT-PCR and western blot were performed to analysis mRNA and proteins expression. Cell proliferation was evaluated using MTT assay and colony formation assay. Transwell and scratch-wound healing assays were conducted to detected cell migration ability. RASSF1A was downregulated in TGFβ2-induced SRA01/04 cells. RASSF1A overexpression inhibited the cell viability, colony formation and migration abilities of SRA01/04 cells induced by TGFβ2. Overexpression of RASSF1A suppressed TGFβ2-induced EMT of SRA01/04 cells, which was manifested as inhibition of EMT-related proteins α-SMA, Vimentin, Snail and Fn expression. Moreover, RASSF1A down-regulated the expression of HDAC6. Importantly, HDAC6 reversed the effects of RASSF1A on SRA01/04 cells. These findings indicate that RASSF1A prevented TGFβ2-induced proliferation, migration, and EMT of LECs by regulating HDAC6 expression, suggesting that RASSF1A holds promise as a potential target for cataracts treatment.

Hippo pathway in intestinal diseases: focusing on ferroptosis

The incidence of intestinal diseases, such as inflammatory bowel disease, gastric cancer, and colorectal cancer, has steadily increased over the past decades. The Hippo pathway is involved in cell proliferation, tissue and organ damage, energy metabolism, tumor formation, and other physiologic processes. Ferroptosis is a form of programmed cell death characterized by the accumulation of iron and lipid peroxides. The Hippo pathway and ferroptosis are associated with various intestinal diseases; however, the crosstalk between them is unclear. This review elaborates on the current research on the Hippo pathway and ferroptosis in the context of intestinal diseases. We summarized the connection between the Hippo pathway and ferroptosis to elucidate the underlying mechanism by which these pathways influence intestinal diseases. We speculate that a mutual regulatory mechanism exists between the Hippo pathway and ferroptosis and these two pathways interact in several ways to regulate intestinal diseases.

Overview of Three Proliferation Pathways (Wnt, Notch, and Hippo) in Intestine and Immune System and Their Role in Inflammatory Bowel Diseases (IBDs)

Inflammatory bowel disease (IBD) is a disorder, which involves the gastrointestinal (GI) tract consisting Crohn's disease (CD) and ulcerative colitis (UC). The etiology of this disease is not yet clear and, hence, there are numerous medications and treatments for patients with IBD, although a definite and permanent treatment is still missing. Therefore, finding novel therapeutic approaches are vital for curing patients with IBD. In the GI tract, there are various lineages of cells with different roles that their existence is necessary for the barrier function of intestinal epithelial cells (IECs). Therefore, signaling pathways, which manage the hemostasis of cell lineages in intestine, such as Wnt, Notch, and Hippo, could have crucial roles in regulation of barrier function in the intestine. Additionally, these signaling pathways function as a governor of cell growth, tissue homeostasis, and organ size. In patients with IBD, recent studies have revealed that these signaling pathways are dysregulated that it could result in depletion or excess of a cell lineage in the intestine. Moreover, dysregulation of these signaling pathways in different cell lineages of the immune system could lead to dysregulation of the immune system's responses in IBD. In this article, we summarized the components and signaling of Wnt, Notch, and Hippo pathways and their role in the intestine and immune system. Furthermore, we reviewed latest scientific literature on the crosstalk among these three signaling pathways in IBD. An overview of these three signaling pathways and their interactions in IBD could provide a novel insight for prospective study directions into finding efficient medications or treatments.

microRNA-939 Promotes the Vitality of Human Breast Cancer Cells via Inhibition of E2F1/P73 Signaling

We assessed miR-939’s role in breast cancer (BC) and its molecular mechanism. PCR was performed to detect miRNA levels. Correlations between miR-939 and patients’ pathological information were analyzed. After transfection of E2F1 plasmid, P73 plasmid, si-E2F1, si-P73, miR-939 mimic or si-miR-939, cell proliferation and apoptosis were measured. The miR-939 target gene was proved by a luciferase assay. Protein and mRNA levels of E2F1 and P73 were detected by immunoblotting and PCR, and corresponding proliferation or apoptosis were assessed. MiR-939 expression was significantly increased in BC and associated with TNM staging, Ki-67 enhancement, and shorter disease-free survival time. In BC clinical samples, E2F1 expression is negatively correlated with miR-939 expressions. Overexpressing miR-939 stimulated growth but suppressed cell apoptosis. Functional analysis indicated E2F1 is the target gene of miR-939, and overexpression of miR-939 significantly downregulated E2F1 and P73. Silencing of E2F1 or P73 significantly promoted MDA-MB-231 cell proliferation and inhibited apoptosis. Overexpression of E2F1 plasmid or P73 plasmid significantly inhibited MDA-MB-231 cell proliferation but induced apoptosis. Transfection of P73 or E2F1 plasmid abolished miR-939’s effects on proliferation and apoptosis. miR-939 promotes breast cancer progression by downregulation of E2F1 to inhibit P73 pathway, thereby promoting proliferation and inhibiting apoptosis.

LATS1 K751 acetylation blocks activation of Hippo signalling and switches LATS1 from a tumor suppressor to an oncoprotein

Large tumor suppressor 1 (LATS1) is the key kinase controlling activation of Hippo signalling pathway. Post-translational modifications of LATS1 modulate its kinase activity. However, detailed mechanism underlying LATS1 stability and activation remains elusive. Here we report that LATS1 is acetylated by acetyltransferase CBP at K751 and is deacetylated by deacetylases SIRT3 and SIRT4. Acetylation at K751 stabilized LATS1 by decreasing LATS1 ubiquitination and inhibited LATS1 activation by reducing its phosphorylation. Mechanistically, LATS1 acetylation resulted in inhibition of YAP phosphorylation and degradation, leading to increased YAP nucleus translocation and promoted target gene expression. Functionally, LATS1-K751Q, the acetylation mimic mutant potentiated lung cancer cell migration, invasion and tumor growth, whereas LATS1-K751R, the acetylation deficient mutant inhibited these functions. Taken together, we demonstrated a previously unidentified post-translational modification of LATS1 that converts LATS1 from a tumor suppressor to a tumor promoter by suppression of Hippo signalling through acetylation of LATS1.

M2 Macrophage-Derived Exosomal miR-590-3p Attenuates DSS-Induced Mucosal Damage and Promotes Epithelial Repair via the LATS1/YAP/ β-Catenin Signalling Axis

BACKGROUND AND AIMS

M2 phenotype macrophages are involved in the resolution of inflammation and intestinal repair. Exosomes are emerging as important mediators of intercellular communication in the mucosal microenvironment.

METHODS

M2 macrophages were transfected with or without miR-590-3p. Exosomes derived from M2 macrophages were isolated and identified. Proliferation and wound healing were tested in vitro and compared between groups. The mechanism involving LATS1, and activation of YAP and β-catenin signalling was investigated by using plasmid transfection, western blotting, immunofluorescence and luciferase reporter assays. The effect of exosomes in vivo was detected in dextran saline sulphate [DSS]-induced murine colitis.

RESULTS

First, we demonstrated that M2 macrophages promoted colonic epithelial cell proliferation in an exosome-dependent manner. Epithelial YAP mediated the effect of M2 macrophage-derived exosomes [M2-exos] in epithelial proliferation. Moreover, miR-590-3p, which was significantly enriched in M2-exos, could be transferred from macrophages into epithelial cells, resulting in the enhanced proliferation and wound healing of epithelial cells. Mechanistically, miR-590-3p suppressed the expression of LATS1 by binding to its coding sequence and subsequently activated the YAP/β-catenin-modulated transcription process to improve epithelial cell wound-healing ability. miR-590-3p also inhibited the induction of pro-inflammatory cytokines, including tumour necrosis factor-α, interleukin-1β [IL-1β] and IL-6. More importantly, repression of miR-590-3p in M2-exos resulted in more severe mucosal damage and impaired colon repair of mice compared with those in M2-exo-treated mice after DSS-induced colitis.

CONCLUSION

M2 macrophage-derived exosomal miR-590-3p reduces inflammatory signals and promotes epithelial regeneration by targeting LATS1 and subsequently activating YAP/β-catenin-regulated transcription, which could offer a new opportunity for clinical therapy for ulcerative colitis.

The role of the Hippo pathway in the pathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic and recurrent inflammatory disorder that primarily comprises Crohn's disease (CD) and ulcerative colitis (UC). Owing to its increasing prevalence in Eastern countries and the intractable challenges faced during IBD treatment, extensive research on IBD has been carried out over the last few years. Although the precise aetiology of IBD is undefined, the currently accepted hypothesis for IBD pathogenesis considers it to be a combination of environment, genetic predisposition, gut microbiota, and abnormal immunity. A recently emerged signalling pathway, the Hippo pathway, acts as a key regulator of cell growth, tissue homoeostasis, organ size, and has been implicated in several human cancers. In the past few years, studies have revealed the importance of the Hippo pathway in gastrointestinal tract physiology and gastrointestinal diseases, such as colorectal cancer and IBD. However, the role of the Hippo pathway and its exact impact in IBD remains to be elucidated. This review summarises the latest scientific literature on the involvement of this pathway in IBD from the following perspectives that account for the IBD pathogenesis: intestinal epithelial cell regeneration, immune regulation, gut microbiota, and angiogenesis. A comprehensive understanding of the specific role of the Hippo pathway in IBD will provide novel insights into future research directions and clinical implications of the Hippo pathway.

Interrelations of Apoptotic and Cellular Senescence Genes Methylation in Inflammatory Bowel Disease Subtypes and Colorectal Carcinoma in Egyptians Patients

Ras-related domain family member 1 transcript variant A (RASSF1A) controls apoptosis and cell proliferation while p14/ARF gene has a regulatory role in cellular senescence. Failure of apoptosis and cellular senescence occurs during inflammatory bowel disease (IBD) and colorectal cancer (CRC). To reveal the role of peripheral leukocyte promoter methylation of RASSF1A and p14/ARF in the pathogenesis of IBD subtypes and CRC we investigated the methylation state of the two genes by methylation-specific polymerase chain reaction (MSP-PCR) in 60 CRC patients, 60 patients with IBD; 27 with ulcerative colitis and 33 had Crohn's disease and also in 30 healthy subjects. Methylated RASSF1A and p14/ARF genes were detected in 55% and 60% of CRC, while the frequency of the methylated RASSF1A and p14/ARF genes was 23.3% and 43.3% in IBD patients and 3.3% and 13.3% in the control group (P = 0.000 each). Also, the frequency of methylated RASSF1A gene was significantly higher in ulcerative colitis than in Crohn's disease, while a non-significant frequency of methylated p14/ARF was detected between ulcerative colitis and Crohn's disease. Furthermore, methylated RASSF1A and p14/ARF were associated with the grade of CRC but not associated with the age of patients, family history, or tumor location. Results suggest that methylated RASSF1A and p14/ARF are related to CRC and IBD pathogenesis and may be used as molecular biomarkers for early detection of CRC and IBD.