Establishing apoptosis resistant cell lines for improving protein productivity of cell culture

Abstract

The authors established apoptosis resistant COS-1, myeloma, hybridoma, and Friend leukemia cell lines by genetically engineering cells, aiming at more efficient protein production by cell culture. COS-1 cells, which are most widely used for eukariotic gene expression, were transfected with human bcl-2 gene. Both bcl-2 and mock transfected COS-1 cells were cultured at low (0.2%) serum concentration for 9 days. The final viable cell number of the bcl-2 transfected cells was ninefold of that of the mock transfectants. Both bcl-2 and mock transfectants were further transfected with the vector pcDNA-λ containing SV40 ori and immunoglobulin λ gene for transiently expressing λ protein. The bcl-2 expressing COS-1 cells produced more λ protein than the mock transfected COS-1 cells after 4 days posttransfection.Mouse myeloma p3-X63-Ag.8.653 cells, which are widely used as the partner for preparing hybridoma, and hybridoma 2E3 cells were transfected with human bcl-2 gene. Both bcl-2 transfected myeloma and hybridoma survived longer than the corresponding original cells in batch culture. The bcl-2 transfected 2E3 cells survived 2 to 4 four days longer in culture, producing 1.5- to 4-fold amount of antibody in comparison with the mock transfectants.Coexpression of bag-1 with bcl-2 improved survival of hybridoma 2E3 cells more than bcl-2 expression alone. The bag-1 and bcl-2 coexpressing cells produced more IgG than the the cells expressing bcl-2 alone.Apoptosis of Friend murine erythroleukemia(F-MEL) cells was suppressed with antisense c-jun expression. The antisense c-jun expressing cells survived 16 days at non-growth state.