Differential behaviour of normal, transformed and Fanconi's anemia lymphoblastoid cells to modeled microgravity

Abstract

Background: Whether microgravity might influence tumour growth and carcinogenesis is still an open issue. It is not clear also if and how normal and transformed cells are differently solicited by microgravity. The present study was designed to verify this issue.

Methods: Two normal, LB and HSC93, and two transformed, Jurkat and 1310, lymphoblast cell lines were used as representative for the two conditions. Two lymphoblast lines from Fanconi's anemia patients group A and C (FA-A and FA-C, respectively), along with their isogenic corrected counterparts (FA-A-cor and FA-C-cor) were also used. Cell lines were evaluated for their proliferative ability, vitality and apoptotic susceptibility upon microgravity exposure in comparison with unexposed cells. Different parameters correlated to energy metabolism, glucose consumption, mitochondrial membrane potential (MMP), intracellular ATP content, red-ox balance and ability of the cells to repair the DNA damage product 8-OHdG induced by the treatment of the cells with 20 mM KBrO3 were also evaluated.

Results: Transformed Jurkat and 1310 cells appear resistant to the microgravitational challenge. On the contrary normal LB and HSC93 cells display increased apoptotic susceptibility, shortage of energy storages and reduced ability to cope with oxidative stress. FA-A and FA-C cells appear resistant to microgravity exposure, analogously to transformed cells. FA corrected cells did shown intermediate sensitivity to microgravity exposure suggesting that genetic correction does not completely reverts cellular phenotype.

Conclusions: In the light of the reported results microgravity should be regarded as an harmful condition either when considering normal as well as transformed cells. Modeled microgravity and space-based technology are interesting tools in the biomedicine laboratory and offer an original, useful and unique approach in the study of cellular biochemistry and in the regulation of metabolic pathways.

Figure 1

Growth and vitality in ground unexposed (open columns) or microgravity exposed (close columns) cells. A: LB, HSC93, Jurkat and 1310 cells. B: FA-A-cor, FA-C-cor, FA-A and FA-C cells. Panel a: Proliferative ability of cells by BrdU assay. Proliferation of LB cells growing in normal conditions was used as reference for the other cell lines. Panel b: Percentage of dying cells after trypan blue staining. Panel c: Percentage of apoptotic cells after sub-G1 peak quantification in flow cytometry. Panel d: PARP activity fluctuactions after autoradiography of cells incubated with (³²P)NAD.

Figure 2

Variations in MMP in ground unexposed (open columns) or microgravity exposed (close columns) cells. A: LB, HSC93, Jurkat and 1310 cells. B: FA-A-cor, FA-C-cor, FA-A and FA-C cells.

Figure 3

Glucose consumption (mg/ml/cell) in ground unexposed (open columns) or microgravity exposed (close columns) cells. A: LB, HSC93, Jurkat and 1310 cells. B: FA-A-cor, FA-C-cor, FA-A and FA-C cells.

Figure 4

Recovery in intracellular ATP in ground unexposed (solid symbols) or microgravity exposed (open symbols) cells. A: LB, HSC93, Jurkat and 1310 cells. B: FA-A-cor, FA-C-cor, FA-A and FA-C cells. The content of ATP in the various cell lines before exposure to microgravity was normalized to 100%.

Figure 5

MBA-TBA (TBARS, nmol/mg protein) quantification in ground unexposed (open columns) or microgravity exposed (close columns) cells. A: LB, HSC93, Jurkat and 1310 cells. B: FA-A-cor, FA-C-cor, FA-A and FA-C cells.

Figure 6

Time-dependent removal of 8-OHdG in ground unexposed (close symbols) or microgravity exposed (open symbols) cells. A: LB and HSC93 cells. B: Jurkat and 1310 cells. C: FA-A and FA-C cells. D: FA-A-cor and FA-C-cor cells.