Changes of PI3K/AKT/BCL2 signaling proteins in congenital Giant Nevi: melanocytes contribute to their increased survival and integrity

Congenital Giant Nevi (CGN) are rare melanocytic lesions with the potential to regress into malignant melanoma. Simultaneous up-regulation and cooperative interactions of signaling pathways are crucial events in the pathogenesis of melanocytes. Our study aimed to identify changes in the expression and activation of proteins controlling survival and/or apoptosis of the key signaling pathways PI3K/AKT/BCL2 and Wnt/β-catenin of CGN melanocytes. We applied a model of cultured melanocytes from paired CGN and normal appearing skin, and Western blot (WB) analyzed the expression and activation profile of survival and anti-apoptotic proteins of these signaling pathways, growth pattern, cell cycle and apoptosis. WB analysis demonstrated a significant higher expression level of activated AKT and of BCL2 proteins in the CGN melanocytes compared with paired melanocytes from normal appearing skin. A relative increase in the level of GSK3 and FOXO1 proteins, down stream targets of AKT, as well as of pβ-catenin was also detected in the CGN melanocytes compared with the controls. These changes were not affected by growth of the CGN melanocytes in reduced serum (starvation). Both cell populations shared a similar growth pattern, with no significant differences in the proportion of apoptotic cells and in cell cycle fractions. These data demonstrate for the first time, changes in signaling proteins of cultured CGN melanocytes. Further, suggesting that the changes in AKT/BCL2 signaling molecules might mediate growth and anti-apoptosis processes at least in part, thus increasing the survival potential of CGN melanocytes and maintaining their integrity.

Cytotoxicity of NF-κB inhibitors Bay 11-7085 and caffeic acid phenethyl ester to Ramos and other human B-lymphoma cell lines

OBJECTIVE

The viability of normal and malignant B-cells was shown to depend on the constitutive activation of the nuclear factor (NF)- kappaB pathway. Thus, attempts to find efficient inhibitors of NF-kappaB play a central role in the search for novel anti-B lymphoma therapies. We studied the effects of two NF-kappaB inhibitors, Bay 11-7085 (BAY) and caffeic acid phenethyl ester (CAPE), on the viability of B-lymphoma cell lines.

METHODS

We investigated the mechanism(s) of the cytotoxic effect of the NF-kappaB inhibitors, BAY, and CAPE on human-lymphoma and nonhematological cell lines.

RESULTS

BAY and CAPE were shown to kill Ramos-Burkitt's lymphoma cells with IC(50) values of 0.7 microM and 4 microM, respectively. The rapid killing by BAY (h) vs the slower killing by CAPE (1-3 days), and their differential effects on the stages of the cell cycle, indicated that these drugs induce killing by different mechanisms. BAY and CAPE induced a loss of the cytoplasmic compartment and generated pyknotic nuclei, which lacked nuclear or nucleosomal fragmentation, features characteristic of necrosis rather than apoptosis. BAY also induced a rapid loss of the mitochondrial potential and rapid inhibition of p65 NF-kappaB binding to its kappaB motif without reducing the level of nuclear p65.

CONCLUSION

Our results indicate that BAY causes a necrotic rather than apoptotic cell death, either through its effect on the NF-kappaB pathway and/or by affecting additional molecular targets. The high sensitivity of B-lymphoma cell lines to the cytotoxicity of BAY, justify further research to explore its potential therapeutic effect on human B lymphomas.

Decreased neutrophil thromboxane A2 and endothelial PGI2 production in the postoperative period. An in vitro assay for detection of neutrophil and plasma dysfunction

Severe trauma results in reversible abnormalities in neutrophil function, but the specific role in the pathogenesis of postoperative sepsis is undetermined. Twenty adult patients undergoing elective surgical procedures were studied. Blood samples were obtained prior to and 24 hours after operation. Blood neutrophils were isolated and incubated (10(7) cells/mL) on bovine vascular endothelial cell monolayers. Untreated plasma or zymosan-activated plasma (ZAP) or 65 C inactivated plasma was added, and TxB2 and 6-keto PGF1 alpha production measured after 2 hours. Endothelial damage was detected by light and scanning electron microscopy beginning 2 and 4 hours after treatment. Preoperatively, neutrophil TxB2 release was less than 200 pg/mL; following ZAP it was 2153 pg/mL (p less than 0.001), with untreated plasma 1055 pg/mL (p less than 0.005) and inactivated plasma 764 pg/mL (p less than 0.01). Neutrophil TxB2 release on a plastic dish was not different from incubation on endothelium. Endothelial 6-keto PGF1 alpha release following addition of untreated plasma preoperatively was 1308 pg/mL (p less than 0.01), and with ZAP 1305 pg/mL (p less than 0.01). Activated neutrophils did not alter 6-keto PGF1 alpha production. Postoperatively, neutrophil TxB2 production in response to ZAP was 1092 pg/mL, which was significantly reduced compared to the preoperative response (p less than 0.01). Endothelial damage by activated neutrophils in the postoperative period demonstrated on scanning electron microscopy was also reduced; 6-keto PGF1 alpha release in the postoperative period inducted by ZAP was 569 pg/mL and by untreated plasma 549 pg/mL, which was significantly lower than in the preoperative period (p less than 0.05 and p less than 0.05, respectively). No difference in chemotaxis was demonstrated. It is concluded that operative trauma is followed by lowered neutrophil TxB2 release, appearance of a plasmatic factor that depresses endothelial 6-keto PGF1 alpha production, as well as decreased neutrophil-induced endothelial damage. The neutrophil-endothelial monolayer system is a sensitive method for detection of neutrophil and plasmatic dysfunction.

Expression of p53 in human leukemia and lymphoma

Analysis of fresh human tumors have indicated that patients with B type lymphoproliferative diseases and the majority of patients with acute lymphoblastic leukemia (ALL) express elevated levels of p53 production. It is suggested that in these human malignancies, p53 may provide a novel tool for monitoring cancer activity. Conversely, p53 is not expressed in acute myeloid leukemias, myeloproliferative diseases, or myeloid leukemic cell lines. Analysis of the p53 gene structure indicated the existence of similar patterns of p53 restriction fragments in producer and nonproducer cells, which suggests that the p53 gene is not altered in the latter. However, in one case of acute promyelocytic leukemia (APL), we have observed a rearrangement in the p53 gene. Karyotype analysis has indicated that these APL cells do not contain the typical 15;17 translocation. In other APL patients who exhibit a 15;17 translocation, we found no genomic changes of the p53, suggesting that the p53 gene, which was recently mapped to the short arm of chromosome 17 in the human, is not structurally related to the typical chromosomal break point found in the long arm of chromosome 17 of APL patients.

Ultrastructural, cell membrane, and cytogenetic characteristics of B-cell leukemia, a murine model of chronic lymphocytic leukemia

A murine model of a spontaneous, transplantable BALB/c B-cell leukemia (BCL1) is described. Extreme leukemia and splenomegaly develop in H-2d-compatible recipients of tumor cells. Tumor cells are medium to large lymphocytes that can be transformed into plasmacytoid cells following in vitro stimulation with lipopolysaccharide. Karyotypic analysis of transformed tumor cells reveals 36 chromosomes with several monosomies and 7 markers chromosomes. The ultrastructure of the tumor cells was studied using transmission and scanning electron microscopy. Although the appearance of tumor cells seems normal by morphological criteria, an impaired capping ability was documented using the fluorescein-conjugated concanavalin A-binding test. Impaired capping ability was documented before leukemia was overt as early as 1 to 3 days following inoculation of tumor cells. The B-cell leukemia (BCL1) provides a useful murine model for the study of various aspects of human bone marrow-derived malignant disorders.