Effects of spatial configuration on tumor cells transgene expression

CASAIS, CECILIA C.; KARARA, ARMANDO L.; GLIKIN, GERARDO C.; FINOCCHIARO LILIANA M.E.

Gene therapy & molecular biology

Gene Therapy Press

Lugar: Mountain View, California 94043, USA; Año: 2006 vol. 10 p. 207 - 222

1529-9120

We investigated the impact of the multicellular architecture on transgene expression of LM05e and LM3 spontaneous Balb/c-mammary adenocarcinoma and HEp-2 human laryngeal squamous carcinoma cell lines. When transferred from monolayers to spheroids, tumor cells strongly enhanced transient transgene expression, which surprisingly was still detectable 75 days after lipofection. The cytomegalovirus immediate early promoter (CMVie) yielded a very high b-galactosidase (bgal) transgene expression, which resulted 8-, 6- and 3-fold greater in LM05e, LM3 and HEp-2 spheroids than the corresponding monolayers. The SV40 early promoter displayed both, a lower spheroids/monolayers ratio and about 10% of bgal expression driven by CMVie. Cis-addition of Epstein Barr virus EBNA-1/oriP cassette enhanced the CMVie-driven transgene expression only in human HEp-2. Deletion of a 325 bp 5’ fragment of the CMVie promoter dropped spheroids bgal expression to 5%. This effect was restored to 10-25% or 25-60% by the insertion of one KCS (18 bp) or four myc-max consensus sequences (67 bp) respectively. When spheroids disassembled and grew as monolayers, bgal activity dropped accordingly. Our results demonstrated that the spatial configuration determined the expression enhancement and persistence in spheroids, being an event: fully reversible, proportional to spheroid compactness and independent of plasmid integration into the host genome.