RESUMO
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMO
Heat-shock protein 5 (HSPA5) is a marker for poor prognosis in breast cancer patients and has an important role in cancer progression, including promoting drug resistance and metastasis. In this study, we identify that the specific lysine residue 447 (K447) of HSPA5 could be modified with polyubiquitin for subsequent degradation through the ubiquitin proteasomal system, leading to the suppression of cell migration and invasion of breast cancer. We further found that GP78, an E3 ubiquitin ligase, interacted with the C-terminal region of HSPA5 and mediated HSPA5 ubiquitination and degradation. Knock down of GP78 significantly increased the expression of HSPA5 and enhanced migration/invasive ability of breast cancer cells. Knock down of histone deacetylase-6 (HDAC6) increased the acetylation of HSPA5 at lysine residues 353 (K353) and reduced GP78-mediated ubiquitination of HSPA5 at K447 and then increased cell migration/invasion. In addition, we demonstrate that E3 ubiquitin ligase GP78 preferentially binds to deacetylated HSPA5. Notably, the expression levels of GP78 inversely correlated with HSPA5 levels in breast cancer patients. Patients with low GP78 expression significantly correlated with invasiveness of breast cancer, advanced tumor stages and poor clinical outcome. Taken together, our results provide new mechanistic insights into the understanding that deacetylation of HSPA5 by HDAC6 facilitates GP78-mediated HSPA5 ubiquitination and suggest that post-translational regulation of HSPA5 protein is critical for HSPA5-mediated metastatic properties of breast cancer.
Assuntos
Neoplasias da Mama/metabolismo , Proteínas de Choque Térmico/metabolismo , Histona Desacetilases/metabolismo , Acetilação , Sequência de Aminoácidos , Animais , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Chaperona BiP do Retículo Endoplasmático , Feminino , Técnicas de Silenciamento de Genes , Proteínas de Choque Térmico/química , Proteínas de Choque Térmico/genética , Desacetilase 6 de Histona , Histona Desacetilases/genética , Humanos , Camundongos SCID , Dados de Sequência Molecular , Invasividade Neoplásica , Metástase Neoplásica , Complexo de Endopeptidases do Proteassoma/metabolismo , Homologia de Sequência de Aminoácidos , UbiquitinaçãoRESUMO
Hemophagocytic syndrome (HPS) in systemic lupus erythematosus(SLE) patients has not commonly been reported. In this case study, we report the first case of Mycobacterium avium complex (MAC)-associated hemophagocytic syndrome in a patient with systemic lupus erythematosus (SLE). This SLE patient, a 15-year-old girl, had been on a high dose of prednisolone (> 0.5mg/kg/day) for more than 3 years. She presented with a spiking fever, hepatosplenomegaly, pancytopenia, hyperferritinemia and adult respiratory distress syndrome. Bone marrow examination revealed hemophagocytosis as well as non-caseating granulomatosis. There was no indication of SLE fare-up. She responded poorly to initial treatment with methyl-prednisolone, intravenous immumoglobulin, etoposide, and drugs for Mycobacterium tuberculosis including rifampin, ethambutol, isoniazid and pyramide. However, gastric lavage culture revealed MAC. Following treatment with clarithromycin, ciprofloxacin and amikacin, her condition gradually improved and she was discharged 3 months after admission. In SLE patients with pancytopenia and hyperferritinemia, MAC-associated HPS should be considered in the differential diagnosis.