The gangliosides as a possible molecular coupling factor between the proportion of radiosensitive cells in vitro and the metastatic potential in vivo within a human melanoma cell line

Abstract

Summary With an experimental model of spontaneous lung metastases in immunosuppressed newborn rats, seven clones and variants with different metastatic potential and gangliosides expression were derived from a single parental human melanoma cell line M4Be. The cellular radiosensitivity of M4Be and its seven sublines was estimated using an in vitro colony assay. The total amount of gangliosides in M4Be and its seven sublines was determined by cell extraction and thin-layer chromatography, while the expression of GD3 gangliosides was estimated by flow cytometry with a monoclonal antibody. The radiation-cell survival curves of most clones and variants derived from M4Be showed a zero dose extrapolation clearly lower than 100%, suggesting that two populations of cells of very different radiosensitivity coexist within each of these clones and variants. Although the proportion of radiosensitive cells could be estimated from the shape of the survival curve, its radiosensitivity is too high to be properly evaluated by the colony assay. The eight survival curves differ essentially in the proportion of radiosensitive cells -which varied from 0% to 40% among M4Be and its seven sublines -whereas the cellular radiosensitivity of the radioresistant population was similar among them. The metastatic potential in vivo of M4Be and its seven sublines was not significantly related to the cellular radiosensitivity of their corresponding radioresistant population, but significantly increased with the fraction of radiosensitive cells. This relationship is valid only when the highly metastatic cells are cultured for no more than five passages in vitro as the fraction of radiosensitive cells is rapidly lost during subcultures. The relationship remains valid in vivo as metastatic melanoma-bearing newborn rats whole body irradiated with 20 cGy show no lung metastasis compared with controls. The radiosensitive cell fraction is inversely correlated with both the total ganglioside content (r= 0.84, P < 0.02) and the number of cells positively labelled with the monoclonal antibody directed to GD3 (r= 0.92, P < 0.001). The incubation of a radiosensitive clone with the exogenous bovine brain ganglioside GM1 significantly increases the proportion of radioresistant cells and suppresses its metastatic potential, while the inhibition of the endogenous gangliosides synthesis in the radioresistant cell line M4Be increases the proportion of radiosensitive cells. This study provides a possible explanation for the correlation between the metastatic potential and the proportion of radiosensitive cells within the seven sublines derived from a single parental human melanoma cell line.

Cell division cycle 25 homolog c effects on low-dose hyper-radiosensitivity and induced radioresistance at elevated dosage in A549 cells

“…Though HRS/IRR is a widely occurring phenomenon, the effect has been shown to be more prominent in proliferating malignant tissues than in quiescent normal tissues [19, 20]. In addition, tumorigenic cells with high metastatic potential have been demonstrated to preferentially exhibit HRS at a much greater level than that seen in poorly metastatic cells [21–22].…”

Low-dose hyper-radiosensitivity of progressive and regressive cells isolated from a rat colon tumour: Impact of DNA repair

“…Clonogenic survival was assessed as previously described (Thomas et al 1997). Briefly, 500 cells were seeded and irradiated 2 or 24 h after plating with doses ranging from 0.05-6 Gy.…”

“…By using seven highly and poorly metastatic clones derived from the same parental human melanoma cell line, we have previously shown that the more the clones show marked HRS response, the more the clones are metastatic (Thomas et al 1997). HRS was also reported in human metastatic skin nodules (Harney et al 2004).…”

The Ganglioside GD3 as the Greek Goddess Hecate: Several Faces Turned Towards as Many Directions

“…Interestingly, studies on a human melanoma M4Be line showed that the lower the expression of GD3 disialoganglioside at the cell surface, the higher their radiosensitivity in vitro and their metastatic potential in vivo (36). Moreover, enrichment with exogenous bovine brain GM1 increased its radioresistance in vitro (37) and suppresses its metastatic potential (38). Thus, the absence of ganglioside on the cell surface is correlated with sensitivity to radiotherapy and high metastatic potential indicating that the cellular distribution of gangliosides can influence the biological outcome of the cell.…”

“…Moreover, enrichment with exogenous bovine brain GM1 increased its radioresistance in vitro (37) and suppresses its metastatic potential (38). Thus, the absence of ganglioside on the cell surface is correlated with sensitivity to radiotherapy and high metastatic potential indicating that the cellular distribution of gangliosides can influence the biological outcome of the cell.…”