c 3T3 cells and their transformed counterparts

Cell Biolog y International Reports, Supplement A, Vol. 5, Sept. 198 1 ADHESION OF B3UB/C 3T3 CELLS AWD THEIR TFLAWSFOBMED COUt?TEEPAETS. Paul Elvin and Clive W. Evans, Department of Anatomy and Experimental Pathology, University of St Andrews, St Andrews, KY16 OTS, Scotland. Tumour cells are often considered to be less adhesive than their non-transformed counterparts, although recent studies have suggested that this may not always be the case. Many factors may contribute to the variations in adhesion rqported for particular cell lines including aggregation conditions (shear, time, cell no.), physical and chemical treatment (pipetting, enzymes) and cell growth conditions. We have studied the aggragation of Balb/c 3T3 cells and their SV40 transformed derivatives under known shear conditions and at different growth stages. of both SV40-3T3 and 3T3 cells increases with culture density up to Adhesiveness about lo5 cells cm-' and is affected by position in the cell cycle. When 3T3 cells were synchronized with thymidine and nocadasole , Gl phase cells were found not to differ significantly in their adhesiveness from control (unsynchronized) cells, whereas S phase cells were of lower adhesiveness and M phase cells were of greater adhesiveness. SV40-3T3 cells are generally less adhesive than 3T3 cells from equivalent growth sta es at aggregation shears <45 set-'. However, at shears between 45- 450 set- 9 the adhesion profile reverses with SV40-3T3 cells becoming more adhesive. The ability for transformed cells to remain adhesive under relativelyhigh shear conditions may facilitate extravasation from blood vessels during metastasis.

EFFECTS OF ALKALINE pH AND GLUTAMINE ON GROWTHAND MULTIPLICATION OF 3T3-CELLS. L%-!Lh Eng6a%m and An.dm Z-bag, Dcpa~~&~cti od T~no& P&oCoqy, Katrofinha HObph.& S-104 01 Stickho.& Sweden. It was recently found that quiescent serum-starved swiss 3T3-cells in sparse, non-confluent cultures could be stimulated to initiate DNA-synthesis in low (0.5%) serum concentration by a short (2-10 minutes) exposure to alkaline (pH 8.5-10) medium. Alternatively quiescent cells could be stimulated to undergo DNA-synthesis and mitosis in low serum (0.5%) concentration after exposure to a medium with a relative glutamine excess. Unlike the growth stimulation induced by addition of 10% serum, a short alkaline treatment or a relative glutamine excess induced only a temporary effect. The cells progressed through a single cell cycle and then reentered quiescence. Most studies concerning control of cellular proliferation have focused on DNAsynthesis and cell division and little is known whether or not different mitogenic stimuli induce a coordinate balanced growth response also including cellular enlargment. It became of interest to investigate whether the different means of stimulatior in high or in low serum concentration actually induced such a balanced coordinate growth response. A great difference in the coordinate cellular response to the different types of mitogenic stimuli was observed. Serum addition to quiescent cells resulted in a complete "balanced" growth response including DNA-replication and mitosis as well as a preserved cell size homeostasis. On the other hand mitogenic stimulation in low by a short alkaline treatment or by a relative (0.5%) serum concentration (i.e. glutamine excess) lead to an imbalanced growth with a disturbed ceil1 size homeostasis. By these two latter means of stimulation it was possible to initiate DNAsynthesis and one cell division without any concomitant increase in cell size.

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