Contributions of autophagic and apoptotic mechanisms to CrTX-induced death of K562 cells.

Previous studies reported that the neurotoxin, Crotoxin, isolated from the venom of South American rattlesnake had potent anti-tumor activity. Here, we investigated the involvement of autophagy and apoptosis in the Crotoxin-induced death of chronic myeloid leukemia cell line K562 cells. The neurotoxin dose dependently inhibited the viability of K562 cells. Crotoxin stimulated the autophagic activity as evidenced by the appearance of punctuate monodansylcadaverine (MDC) fluorescence staining in the cytoplasm and increased the formation of autophagosomes. Crotoxin caused the collapse of the mitochondrial membrane potential, release of cytochrome c and activation of caspase-3. Caspase inhibitors attenuated Crotoxin-induced K562 cell death, while blockage of autophagy maturation with 3-methyladenine (3-MA) and NH4Cl potentiated the neurotoxin's cytotoxicity. These results suggest that an apoptotic mechanism contributes to the Crotoxin-induced death of K562 cells, while the activation of autophagy delays neurotoxin-induced apoptosis.

Osteopontin is a novel prognostic biomarker in early-stage non-small cell lung cancer after surgical resection.

PURPOSES: Osteopontin (OPN), an extracellular matrix-secreted phosphorylated glycoprotein, has been reported overexpressed in many solid tumors. As an important part of lung cancer, the high recurrence of non-small cell lung cancer (NSCLC) also attracted great attention of scientists. METHODS: In this study, we investigated the expression of OPN and the relationship with prognosis of NSCLC patients. We measured the expression of OPN among 163 NSCLC samples by immunohistochemical method and compared the expression of these 28 matched cDNA between tumor and peritumoral tissue by real-time polymerase chain reaction. RESULTS: We demonstrated that the percentages of positive OPN expression is 66.8 % and OPN expression in tumor site was much higher than the tissue adjacent to carcinoma (p = 0.0046). By further analysis, we found that OPN expression was significantly correlated with poor prognosis of NSCLC. Moreover, for early-stage patients, OS and DFS rates of OPN (-) group were significantly higher than OPN (+) group. For advanced-stage patients, OPN expression was only associated with OS rates. CONCLUSIONS: These results suggest that OPN is commonly expressed in NSCLC and may guide the evaluation of prognosis with NSCLC, especially for early-stage patients.

Gene therapy in B-NHL cell line using adenovirus-mediated transfer of secretable trimeric TRAIL gene expression driven by CD20 promoter.

CD20 is a crucial target to B-non-Hodgkin lymphoma (NHL), in fact, a humanized anti-CD20 monoclonal antibody, rituximab, is widely applied in clinical practice. However, resistance to rituximab often occurs in B-NHL patients, which has encouraged us to find new medications to treat B-NHL. In this study, we designed a gene therapy strategy targeting CD20 at a transcriptional level mediated by adenovirus, in which the stTRAIL gene was driven by a specific CD20 promoter fragment. We cloned the CD20 promoter from genome DNA of BJAB cell, a CD20-positive cell line, and identified its specific transcriptional activity with a dual-luciferase reporter assay system. Meanwhile, we constructed the stTRAIL gene sequence, which contained secretion signal, isoleucine zipper, and soluble TRAIL gene sequence, in which the isoleucine zipper facilitated the product of this gene sequence to form a functional homotrimer. The recombinant adenovirus was termed as AdP20-stTRAIL, which carried on the fused gene of the CD20 promoter fragment and the stTRAIL gene. Our studies confirmed that the stTRAIL could be expressed and secreted from BJAB cells infected with AdP20-stTRAIL specifically, and it inhibited the growth of these infected BJAB cells in vitro and in vivo. Our results indicate that the gene therapy using stTRAIL gene driven by a CD20 promoter may be an effective strategy in B-NHL treatment.

Autophagy is involved in cytotoxic effects of crotoxin in human breast cancer cell line MCF-7 cells.

AIM: To investigate the role of crotoxin (CrTX)-induced autophagy in the death of MCF-7 cells, a caspase-3-deficient, human breast cancer cell line. METHODS: Cultured MCF-7 cells were treated with various doses of CrTX, a phospholipase A2 (PLA2) isolated from the venom of the South American rattlesnake, Crotalus durissus terrificus. The cytotoxicity of CrTX in the presence and absence of caspase inhibitors was measured with methyl thiazolyl tetrazolium (MTT) and lactate dehydrogenase (LDH) leakage assays. The activation of autophagy was determined with transmission electron microscope and monodansylcadaverin (MDC) labeling. The upregulation of lysosomal enzymes, the release of cytochrome c (cyto-c), and the nuclear translocation of the apoptosis inducing factor (AIF) were examined by immunoblotting and immunofluorescence. RESULTS: CrTX inhibited the viability of MCF-7 cells in a dose- and time-dependent manner. CrTX-activated autophagy was revealed by punctuate MDC labeling, and an increase in the formation of autophagosomes as well as apoptosis, as evidenced by nuclear condensation and fragmentation. The activation of cathepsin B, D, and L, in addition to the release of cytochrome c and the relocation of AIF into nuclei, were observed after CrTX treatment. Autophagy inhibitors 3-methyladenine (3-MA), NH4Cl, and the pan-caspase inhibitor, Z-Val-Ala-Asp-fluoromethylketone (Z-Vad-fmk), attenuated CrTX-induced cell death. CONCLUSION: An autophagic mechanism contributes to the apoptosis of MCF-7 cells induced by CrTX.