293 cells with transformed phenotype?

Caroline Szymeczek-Seay seay at niehs.nih.gov
Mon Mar 24 14:34:08 EST 1997

Lloyd Graham wrote:
> At ATCC+12 passages, my 293 cells (HEK293) have spontaneously changed
> phenotype to poorly adhered cells that grow in clumps, rather as if they
> have undergone a spontaneous transformation. All I did was subculture them
> in a standard way.
> I have just made a series of stable 293 transfectants (starting with cells
> of normal phenotype) and they too had switched to the novel phenotype by
> the end of the selection procedure.
> Does anyone know what's going on with these cells?
> Thanks,
> Dr. Lloyd Graham
> CSIRO Div. Biomolecular Engineering,
> Australia
Many people in our lab have had the same experience.  I have escaped
this problem so far.  The only thing I can determine that I am doing
differently than other folks in our lab is 1) i always split my cells
very densely (1:3 or 1:5 2 or 3 times a week and 2) I use heat
inactivated fetal calf serum at 10%.  I do not use the media recommended
by ATCC,  but i use DMEM instead.  

this is small help, i know, but good luck.

Caroline SEay

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