Figure 9.

Overexpression of MCT4 in fibroblasts functionally protects both cancer cells and fibroblasts against cell death under co-culture conditions. To assess the possible functional consequences of MCT4 expression in fibroblasts, we generated an hTERT-fibroblast cell line stably overexpressing MCT4. Similarly, we also generated hTERT-fibroblast cell lines overexpressing MCT1, and the vector alone (Lv-105). Then, these three matched fibroblast cell lines were individually co-cultured with GFP-tagged MCF7 cells, and cell death in both fibroblasts and cancer cells was monitored by FACS analysis (See the Materials and Methods section). (A) Note that co-culture with MCT4-expressing fibroblasts protects MCF7 cells against cell death, by nearly 2-fold (p = 0.035). In contrast, the effects of MCT1-expressing fibroblasts on MCF7 cell death were not significant. (B) Note that co-cultured fibroblasts expressing MCT1 (p = 0.01) or MCT4 (p = 0.002) both showed >2-fold protection against cell death. (C) However, when MCT4 fibroblasts were cultured alone, in the absence of cancer cells, they showed a >2-fold increase in cell death (p = 0.005). Thus, expression of MCT4 in fibroblasts functionally prolongs the life of both cancer cells and fibroblasts, under co-culture conditions.