Stress-induced phosphorylation of caveolin-1 and p38, and down-regulation of EGFr and ERK by the dietary lectin jacalin in two human carcinoma cell lines

摘要: We have examined the A431 (human epidermoid carcinoma) and HT29 colorectal cellular responses evoked by lectins of dietary origin, Jacalin Artocarpus integrifolia (native jacalin; nJacalin), peanut agglutinin (PNA) Arachis hypogea, recombinant single-chain jacalin (rJacalin), which has same protein backbone but ∼100-fold less affinity for carbohydrates than nJacalin. All three (nJacalin, rJacalin, PNA) are cycotoxic inhibitors proliferation cells. However, cells recover once not PNA been removed from growth medium. Treatment nJacalin results in morphologically visible cell rounding while retaining membrane integrity when treated at 40 μg ml−1, treatment with did induce such changes. The observed was found to be due stress as phosphorylation caveolin-1 (at tyr14), p38 c-Jun N-terminal kinase were up-regulated, up-regulate same. also down-regulated epidermal factor receptor extracellular signal regulated contrast PNA, failed down-regulate Confocal microscopic studies reveal that is internalized, unlike lectin Agaricus bisporous. Analysis proteins bind an nJacalin-sepharose column revealed binding six eight proteins, significant among them a ∼110 kDa, appears oxygen-regulated 150 (ORP150) (endoplasmic reticulum chaperone) identified its isoelectric point, two-dimensional sodium dodecyl sulfate–polyacrylamide gel electrophoresis mass spectrometric analysis. This 110-kDa band detectable anti-Hsp70 antibody because ORP150 homology Hsp70. presence Hsp70-like on surface immunostaining antibody. Moreover, overexpression resulted dramatic protection against jacalin-induced toxicity, confirming cytotoxicity mediated through ORP150, impairment functions help makes more susceptible death stress. Our suggest responses, consequence binding, may exclusively carbohydrate property alone, other factors protein-protein interactions contribute responses.