Conversion of high grade lymphoma tumor cell line to intermediate grade with tpa and bryostatin 1 as determined by polypeptide analysis on 2D gel electrophoresis

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Abstract
A high‐resolution two‐dimensional polyacrylamide gel electrophoresis (2D‐PAGE) was used for total cellular polypeptide mapping of two established lymphoma cell lines; MANCA, a Burkitt's line representing a high grade lymphoma (HGL) and WSU‐NHL (nodular histiocytic lymphoma) representing an intermediate grade lymphoma (IGL). Gels were digitized and analysed with an image scanning computer using the Elsie 4 system. Polypeptide mapping revealed striking similarities in 1100 polypeptide spots in both types. However, three polypeptides were unique to HGL (Molecular mass/isoelectric point (Mr/PI): 39/4·4, 35/5·6, 33/4·8), and one to IGL (95/4·7). In order to investigate the kinetics of expression of these polypeptides, the two cell lines were treated with two protein kinase C (PKC) activators, tumour promoting 12‐O tetradecanoylphorbol 13‐acetate (TPA) and bryostatin 1. 2D‐PAGE of the treated cells revealed that the HGL line loses its unique polypeptides and expresses a new one. The new polypeptide has the same Mr and PI as that unique to the untreated IGL (95/4·7). TPA or bryostatin 1 treatment of the IGL line for 72 h induced no significant changes. Our data show a unidirectional change from HGL to IGL, supporting the clinical notion that HGL is less differentiated than IGL. It also shows the similarity in the mode of action of bryostatin 1 and TPA in inducing these polypeptide changes.