ABSTRACT
F-box only protein 8 (FBX8), as a critical component of the SKP1-CUL1-F-box (SCF) E3 ubiquitin ligases, has been associated with several malignancies through interacting with a member of proteins. However, the substrates of FBX8 for destruction in the progression of colorectal carcinoma (CRC) need to be explored. Here, we show that loss of FBX8 accelerates chemical-induced colon tumorigenesis. FBX8 directly targets GSTP1 for ubiquitin-mediated proteasome degradation in CRC. GSTP1 promotes the proliferation, invasion, and metastasis of CRC cells. Furthermore, GSTP1 is upregulated in CRC tissue samples and predicts poor prognosis of CRC patients. The inactivation of FBX8 negatively correlated with increased levels and stability of GSTP1 in clinical CRC tissues and FBX8 knockout transgenic mice. These findings identify a novel ubiquitination pathway as FBX8-GSTP1 axis that regulates the progression of CRC, which might be a potential prognostic biomarker for CRC patients.
Subject(s)
Colorectal Neoplasms/pathology , F-Box Proteins/metabolism , Glutathione S-Transferase pi/metabolism , Animals , Biomarkers/metabolism , Cell Line, Tumor , Cell Movement , Cell Proliferation , Colorectal Neoplasms/chemically induced , Colorectal Neoplasms/mortality , Down-Regulation , F-Box Proteins/antagonists & inhibitors , F-Box Proteins/genetics , Glutathione S-Transferase pi/antagonists & inhibitors , Glutathione S-Transferase pi/genetics , Humans , Kaplan-Meier Estimate , Male , Mice , Mice, Inbred C57BL , Mice, Nude , Mice, Transgenic , Prognosis , RNA Interference , RNA, Small Interfering/metabolism , UbiquitinationABSTRACT
OBJECTIVE Toobservetheeffectoftemozolomide(TMZ)incombinationwithtetran-drine(TET)on cell viability,colony formation,migration and cell apoptosis of human glioblastoma U87 cells.METHODS TheviabilityofU87cellstreatedwithTET(8-64μmol·L-1),TMZ(50-400 μmol·L-1 )and TMZ combined with TET (3.2,6.4 μmol·L-1 )was detected by cytotoxicity assays with Cell Counting Kit-8 (CCK-8),the colony formation was detected by Giemsa staining,cell migration ability was detected by Transwell migration assay,cell apoptosis was assayed by flow cytometry using Annexin Ⅴ /PI double staining,and the expression of apoptosis-related proteins expression was detec-tedbyWesternblotting.RESULTS ThedataofCCK-8showedthatTET(r=0.903,P<0.05)orTMZ (r=0.995,P<0.05)could inhibit U87 cell viability alone in a concentration-dependent manner.The cell viability inhibition rate of U87 cells by TMZ co mbined with TET was higher than by TMZ or TET alone. Data showed that the effect of TMZ combined with TET was additive.TMZ 100 μmol·L-1 inhibited U87 cell colony formation and migration ablility compared with normal control.The inhibition rate of U87 cells by TMZ 100 μmol·L-1 combined with TET (3.2 and 6.4 μmol·L-1 )was more significant than by TMZ alone (P<0.05).Compared with TMZ alone,TMZ combined with TET (3.2 and 6.4 μmol·L-1 )signifi-cantly down-regulated the expression of anti-apoptotic protein Bcl-XL,but significantly up-regulated the expression of cleaved caspase 3 protein and cleaved poly(ADP-ribose)polymerase.CONCLUSION TET combined with TMZ can inhibit U87 cell viability,colony formation and migration by activating caspase-dependent apoptotic pathway,resulting in apoptosis.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the correlation between miR-221 and epithelial-mesenchymal transition (EMT) in drug-resistant glioma cells.</p><p><b>METHODS</b>The expression levels of miR-221, PTEN, p-Akt, E-cadherin, vimentin, and MRP1 were quantitatively analyzed in Z1 cells (primary drug-resistant cells), Z2 cells (drug-sensitive cells) and Z2-BCNU cells (drug-resistant cells) using fluorescent real-time PCR and Western blotting.</p><p><b>RESULTS</b>The expression levels of PTEN were significantly increased in Z2 cells compared with Z1 and Z2-BCNU cells which overexpressed miR-221 and vimentin. The expression levels of vimentin, p-Akt and MRP1 were significantly decreased in Z2 cells overexpressing E-cadherin.</p><p><b>CONCLUSION</b>MiR-221 regulates the expression of EMT-related genes through down-regulation of PTEN and activation of PI3-K/Akt signaling.</p>
