Effectiveness of vitamin A acetate for enhancing the production of lung cancer specific monoclonal antibodies

All-trans retinoic acid in combination with sodium butyrate enhances specific monoclonal antibody productivity in recombinant CHO cell line

The effects of all-trans retinoic acid (RA) and sodium butyrate (NaBu) on growth, viability and antibody production of two types of transfected Chinese hamster ovary cell lines (CHO-K1 and CHO-S) were investigated using a batch mode cell culture. By adding 0.5 mM NaBu in the CHO-K1 cell culture, the cell specific productivity (Q_p) and antibody concentration increased by five- and threefold, respectively. The optimal concentration of RA was 100 nM which resulted in twofold increase in antibody production. In a combination model, RA applied at early growth phase of CHO-K1 cells followed by addition of NaBu with lowering culture temperature at the end of stationary phase resulted in two- and threefold increase in Q_p and final antibody concentration, respectively. The latter strategy was also applied on suspended CHO-S cells with enhanced Q_p and antibody concentration, but to a lesser extent than the CHO-K1 cells. In conclusion, our results demonstrate that the addition of RA and NaBu along with lowering the culture temperature can increase cell culture period as well as Q_p and the final concentration of recombinant monoclonal antibody in both CHO-K1 and CHO-S cells without any significant change in binding affinity of the mAb.

Impact on monoclonal antibody production in murine hybridoma cell cultures of adenosine receptor antagonists and phosphodiesterase inhibitors

The effects of different adenosine receptor antagonists and cyclic nucleotide phosphodiesterase (PDE) inhibitors on monoclonal antibody (mAb) titer and cell viability of murine hybridoma cells in culture were measured as part of our investigations to discover additives that enhance mAb production. Specific adenosine receptor antagonists and PDE inhibitors were found to enhance or decrease the titer of immunoglobulin G1 (IgG1) mAbs relative to negative controls, depending on the specific compound and cell line employed. The observed enhancements or decreases in IgG1 mAb titer appeared to be mainly due to an increase or decrease in specific productivity rates (ngmAb/cell), respectively. The different effects of the selective adenosine antagonists suggest that antagonism at the level of the adenosine A2A and A1 or the adenosine A3 receptors result in either enhancement or suppression of IgG1 mAb production by hybridoma cells. Overall, these studies have identified hitherto unknown activities of specific adenosine antagonists and PDE inhibitors which indicate they may have valuable roles as cell culture additives in industrial biomanufacturing processes designed to enhance the yields of mAbs or other recombinant proteins produced by mammalian cell culture procedures.

Retinoic Acid Improves a Hybridoma Culture in a Fructose-Based Medium by Up-Regulation of Fructose IncorporationviaRetinoid Nuclear Receptors

Fructose was focused on as an alternative sugar source to glucose in a hybridoma culture medium because it decreases lactate production during cultivation, leading to cell and product stability. But, not all human hybridoma cell lines grew well in a fructose-based serum-free medium. We found that the addition of all-trans-retinoic acid to the fructose-based medium improved the growth and monoclonal antibody production of hybridoma cell lines by up-regulation of fructose incorporation that represented increased expression of the fructose transporter, GLUT5. Selective activation of retinoid nuclear receptor by synthetic ligands showed that both retinoic acid receptors and retinoid X receptors might be related to the improvement of the fructose-based hybridoma culture. This study might be applicable to cell cultures susceptible to lactate and pH changes as well as hybridoma cultures.

Enhanced antibody production of human-human hybridomas by retinoic acid

The enhancement of human monoclonal antibody production by retinoic acid (RA) was evaluated usingthe human-human hybridoma cell line BD9 underserum-free culture condition. The amount of humanIgG secreted by BD9 hybriodmas was enhanced abouteight-fold by treatment with 10(-7) M of RA for 4days. Northern blot analysis showed that both mRNAlevels of the IgG light and heavy chains were markedlyincreased by RA when compared with control without RAtreatment. On the other hand, it was found thatcontinuous treatment of cells with RA was not alwaysrequired to exhibit the enhancing effect, suggestingthat RA may act as a trigger for IgG gene expression. The comparison between extra- and intracellular IgGamounts by immunoblot analysis suggests that thesecretion rate of IgG may be accelerated by RAtreatment. These results suggest that RA may be aneffective culture additive for efficient production ofhuman monoclonal antibody using human-humanhybridomas.

Enhancement of antibody production by the addition of Coenzyme-Q(10)

Recently, there has been a growing demand for therapeutic monoclonal antibodies (MAbs) on the global market. Because therapeutic MAbs are more expensive than low-molecular-weight drugs, there have been strong demands to lower their production costs. Therefore, efficient methods to minimize the cost of goods are currently active areas of research. We have screened several enhancers of specific MAb production rate (SPR) using a YB2/0 cell line and found that coenzyme-Q(10) (CoQ(10)) is a promising enhancer candidate. CoQ(10) is well known as a strong antioxidant in the respiratory chain and is used for healthcare and other applications. Because CoQ(10) is negligibly water soluble, most studies are limited by low concentrations. We added CoQ(10) to a culture medium as dispersed nanoparticles at several concentrations (Q-Media) and conducted a fed-batch culture. Although the Q-Media had no effect on cumulative viable cell density, it enhanced SPR by 29%. In addition, the Q-Media had no effect on the binding or cytotoxic activity of MAbs. Q-Media also enhanced SPR with CHO and NS0 cell lines by 30%. These observations suggest that CoQ(10) serves as a powerful aid in the production of MAbs by enhancing SPR without changing the characteristics of cell growth, or adversely affecting the quality or biological activity of MAbs.

Induction of cell size vesicles from human lymphoma cell lines and their application to drug carriers

Sodium butyrate (NaB) induced the membrane enclosed cell size vesicles from several IgM producing cell lines. We considered the application of the cell-derived vesicles (CDVs) to drug delivery system (DDS) using the lung cancer specific IgM producing AE6 cell line. Microscopic observation showed that the DiI fluorescence labeled AE6 vesicles were incorporated into the lung cancer cell line A549. The anticancer drug, actinomycin D (actD), contained in AE6 and Ramos vesicles decreased the A549 cell viability to 46 and 62% of control without actD, respectively. The cytotoxic effect in AE6 vesicles was superior to that in the Ramos vesicles that have the lung cancer non-specific IgM on their surfaces. However, the result of the Ramos vesicles suggests that the surface molecules other than IgM may interact with the A549 cells. In our method for vesicle production, more specific and abundant antibodies mounted vesicles can be generated by transfection of their genes into cells followed by NaB treatment. These suggest that the CDVs may be useful for the development of a drug carrier for DDS.

Increased antibody production by retinoids is related to the fusion partner of human hybridomas

An increase of human monoclonal antibody production caused by retinyl acetate and retinoic acid was influenced by the fusion partner rather than the original B lymphocyte used for the human hybridoma generation. Retinoid response of human hybridomas may be at least related to retinoid X receptor-alpha gene expression, which seemed to originate from their fusion partner.