The effect of melittin on proliferation and death of thymocytes

Abstract

The effect of melittin, an activator of phospholipase A 2 , on proliferation and death of rat thymocytes in a broad concentration range was studied. Cell proliferation was estimated by the accumulation of colchicin metaphases, necrotic death was determined from lysis and staining of cells with trypan blue, and apoptosis was assessed from the type of DNA fragmentation, the amount of fragmented DNA, and the percentage of cells with subdiploid DNA. It was shown that low melittin concentrations (below 5 ug/ml) stimulate thymocyte proliferation. At high melittin concentrations, thymocytes die by the primary necrosis type. Throughout the concentration range studied, melittin does not produce apoptosis in thymocytes. Conversely, high melittin concentrations even inhibit thymocyte apoptosis in the control and after irradiation. An inhibitor of RNA synthesis actinomycin D does not affect thymocyte death in the presence of melittin. It is concluded that the activation of phospholipase A 2 can induce necrosis but not apoptosis and thus is not a necessary step in the signaling cascade that initiates apoptosis in thymocytes.

Regulation of activin receptor-interacting protein 2 expression in mouse hepatoma Hepa1-6 cells and its relationship with collagen type IV

“…The signal transduction kinetins regulated the expression of ARIP2 mRNA PMA is the activator of protein kinase C (PKC) [12] , A23187 is the calcium ion vector [13] , forskolin is the kinetin of cAMP-dependent protein kinase A (PKA) [14] and endotoxin LPS can bind with Toll-like receptor 4 on the surface of hepatocytes to stimulate cellular activities non-specifically [15] . To further study the regulation factors of ARIP2 expression, we used all of the above signal transduction activators to stimulate Hepal-6 cells and observed the expression of ARIP2 mRNA.…”

Helminthes and insects: maladies or therapies

“…Bee venom (Apis mellifera) Have anti-tumor activity (Gevod and Birdi 1984) Effective against several tumor cell lines, may act as: calmodulin inhibitor; induces cell membrane lysis and apoptosis; potent pore-forming agent; hyperactivates PLA2 in ras oncogene-transformed cells; acts in different cell signaling pathways; effective against tumors in vivo (Son et al 2007;Hait et al 1983;Duke et al 1994;Shaposhnikova et al 1997;Sharma 1992;Holle et al 2003) Cecropins Cecropia moth (Hyalophora cecropia)…”

“…Therefore, it is expected that analogous synthetic molecules would have great potential, especially in the emergence of multiple-antibiotic-resistant bacteria (Haeberli et al 2000). The oxyopinins from the wolf spider Oxyopes kitabensis, forming pores in lipid membranes (Belokoneva et al 2003), considered the anti-tumor action of other pore-forming peptides, oxyopinins could also be considered as good candidates for anti-cancer therapy (Shaposhnikova et al 1997). Gao et al (2007) have verified the effects of the venom of Macrothele raven (Araneae, Hexathelidae) upon the proliferation and cytotoxicity of human cervical carcinoma cells (2005) and on the human breast carcinoma cell line MCF-7.…”

The Medicinal Value of Biodiversity: New Hits to Fight Cancer

“…Also, hyaluronidases found in the venom of some spiders could be used to increase tissue permeability, thus facilitating the penetration of some drugs, or even being employed directly as antitumor agents (Girisk & Kemparaju, 2007). Other toxins that have been isolated are the oxyopinins from the wolf spider Oxyopes kitabensis, which form pores in lipid membranes (Corzo et al, 2002) and could also be considered as candidates for anticancer therapy (Shaposhnikova et al, 1997).…”