10 research outputs found

    Overexpression of CDC42SE1 in A431 Cells Reduced Cell Proliferation by Inhibiting the Akt Pathway

    No full text
    Cell division cycle 42 (CDC42), a small Rho GTPase, plays a critical role in many cellular processes, including cell proliferation and survival. CDC42 interacts with the CRIB (Cdc42- and Rac-interactive binding) domain of CDC42SE1, a small effector protein of 9 kDa. We found that the expression of CDC42SE1 was reduced in human skin cancer samples relative to matched perilesional control. Exogenous expression of CDC42SE1 but not CDC42SE1H38A (mutation within CRIB domain) in A431 cells (A431SE1, A431SE1-H38A) reduced cell proliferation. Antibody microarray analysis of A431Ctrl and A431SE1 lysate suggested that reduced A431SE1 cells proliferation was due to inhibition of Akt pathway, which was confirmed by the reduced P-Akt and P-mTOR levels in A431SE1 cells compared to A431Ctrl cells. This suggests that CDC42SE1 modulates the CDC42-mediated Akt pathway by competing with other effector proteins to bind CDC42. A431SE1 cells formed smaller colonies in soft agar compared to A431Ctrl and A431SE1-H38A cells. These findings correlate with nude mice xenograft assays, where A431SE1 cells formed tumors with significantly-reduced volume compared to the tumors formed by A431Ctrl cells. Our results suggest that CDC42SE1 is downregulated in skin cancer to promote tumorigenesis, and thus CDC42SE1 might be an important marker of skin cancer progression

    N-WASP attenuates cell proliferation and migration through ERK2-dependent enhanced expression of TXNIP

    No full text
    Neural Wiskott-Aldrich Syndrome Protein (N-WASP) regulates actin cytoskeleton remodeling. It has been known that reduced N-WASP expression in breast and colorectal cancers is associated with poor prognosis. Here, we found reduced N-WASP expression in squamous cell carcinoma (SCC) patient samples. The SCC cell line HSC-5 with reduced N-WASP expression was used to generate HSC-5CN (control) and HSC-5NW (N-WASP overexpression) cells. HSC-5NW cells had reduced cell proliferation and migration compared to HSC-5CN cells. HSC-5NW cells had increased phospho-ERK2 (extracellular signal-regulated kinase 2), phosphorylated Forkhead box protein class O1 (FOXO1) and reduced nuclear FOXO1 staining compared to HSC-5CN cells. Proteasome inhibition stabilized total FOXO1, however, not nuclear staining, suggesting that FOXO1 could be degraded in the cytoplasm. Inhibition of ERK2 enhanced nuclear FOXO1 levels and restored cell proliferation and migration of HSC-5NW to those of HSC-5CN cells, suggesting that ERK2 regulates FOXO1 activity. The expression of thioredoxin-interacting protein (TXNIP), a FOXO1 target that inhibits thioredoxin and glucose uptake, was higher in HSC-5NW cells than in HSC-5CN cells. Knockdown of TXNIP in HSC-5NW cells restored cell proliferation and migration to those of HSC-5CN cells. Thus, we propose that N-WASP regulates cell proliferation and migration via an N-WASP-ERK2-FOXO1-TXNIP pathway.Ministry of Education (MOE)Published versionThis work was supported by the Academic Research Fund Tier 2 (MOE 2013-T2-2-031) and Academic Research Fund Tier 1 (MOE) RG31/20 and RG154/17 grants from the Ministry of Education of Singapore
    corecore