ABSTRACT
BACKGROUND: Gold(III) porphyrin 1a is a new class of anticancer drug, which inhibits cell proliferation of wide range of human cancer cell lines and induces apoptosis in human nasopharyngeal carcinoma cells. However, the underlying signalling mechanism by which gold(III) porphyrin 1a modifies the intracellular apoptosis pathways in tumour cells has not been explained in detail in neuroblastoma cells. METHODS: Cell proliferation and apoptosis were determined by measuring 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Annexin V binding, respectively. Western blot assay was used to detect proteins involved in apoptotic and Akt pathways. In vivo tumour growth was assessed by inoculating tumour cells to nude mice subcutaneously, and gold(III) porphyrin 1a was administrated intravenously. RESULTS: This study assessed the antitumour effect and mechanism of gold(III) porphyrin 1a on neuroblastoma in vitro and in vivo. Gold(III) porphyrin 1a displayed a growth inhibition and induction of apoptosis in neuroblastoma cells effectively in vitro, which was accompanied with release of cytochrome c and Smac/DIABLO and caspases activation. Further studies indicated that gold(III) porphyrin 1a inhibited X-linked inhibitor of apoptosis (XIAP). However, we found that gold(III) porphyrin 1a can induce a survival signal, Akt activation within minutes and could last for at least 24 h. To further confirm association between activation of Akt and the effectiveness of gold(III) porphyrin 1a, neuroblastoma cells were treated with API-2, an Akt-specific inhibitor. API-2 sensitised cells to gold(III) porphyrin 1a-induced apoptosis and growth inhibition. CONCLUSION: These results suggested that Akt may be considered as a molecular 'brake' that neuroblastoma cells rely on to slow down gold(III) porphyrin 1a-induced apoptosis and antiproliferation. Gold(III) porphyrin 1a is a mitochondrial apoptotic stimulus but also activates Akt, suggesting an involvement of Akt in mediating the effectiveness to growth inhibition and apoptosis by gold(III) porphyrin 1a and that inhibition of Akt can enhance the anticancer activity of gold(III) porphyrin 1a in neuroblastoma.
Subject(s)
Metalloporphyrins/pharmacology , Neuroblastoma/drug therapy , Neuroblastoma/enzymology , Proto-Oncogene Proteins c-akt/antagonists & inhibitors , Animals , Apoptosis/drug effects , Apoptosis Regulatory Proteins , Caspases/metabolism , Cell Growth Processes/drug effects , Cell Line, Tumor , Cytochromes c/metabolism , Enzyme Activation/drug effects , Humans , Intracellular Signaling Peptides and Proteins/metabolism , Mice , Mice, Inbred BALB C , Mice, Nude , Mitochondrial Proteins/metabolism , Neuroblastoma/pathology , Phosphorylation/drug effects , Proto-Oncogene Proteins c-akt/metabolism , Xenograft Model Antitumor AssaysABSTRACT
Lymphocyte phenotypes of peripheral blood from 32 SLE patients and 30 normal subjects were studied with 13 kinds of monoclonal antibodies using indirect immunofluorescence technique. The results showed that T4+, T8+, T3+ and T11+ cells decreased in active cases of SLE, while Ia+, IL2R1+ and PCA-1+ cells increased, other B-cell phenotypes (B1, B2, B4, IgM, IgG, IgD) showed no significant difference from those of the normal group. Thus, in inactive SLE after therapeutic management, the numbers of T3+, T11+, T4+, Ia+ and IL2R1+ cells no longer show any abnormality, but the numbers of T8+, PCA-1+ cells and the level of serum IgG are still higher than normal. From the above-mentioned results, it was shown that: 1. The key change in active SLE is the abnormality of immunoregulatory T cells, especially T4+ cells; 2. In active SLE, some of the T cells have been activated in vivo and these immunocompetent cells play an important role in immunoglobulin production of B cells; 3. The hyperactivity of humoral immunity is mainly related to the increase of PCA-1+ cells under the regulation of T cells; 4. Both the lymphocyte phenotypes and clinical features of SLE showed heterogeneity.
