Objective       To observe the effect of different concentrations of tumor cell supernatant on the growth and phenotype transition of fibroblasts.       Methods       Fibroblasts were cultured in conditioned medium containing different concentrations of tumor cell supernatant. Fibroblasts growth tendency was tested by MTT assay

and apoptotic rate was analyzed by flow cytometry. The mRNA and protein expressions of α-SMA and TGF-β

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were tested b

y RT-PCR and Western blotting

respectively.       Results      MTT assay showed that when the ratio of tumor cell supernatant and 2×DMEM∶F12 was 1∶1

the growth of the fibroblasts was significantly promoted(P0.05)

and when the ratio was 2∶1 or the supernatant was completely used

the growth could be restrained. As the concentration of tumor cell supernatant increased

the cells apoptotic rate was rising. The apoptotic rate exhibited significant difference between the ratio of 1∶1 and 1.5∶1 (P0.05). RT-PCR and Western blotting demonstrated that α-SMA and TGF-β

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expressed by fibroblasts that were cultured in normal medium reached the peak level at the fifth day

and then decreased significantly at the seventh day (P0.05). When the ratio of tumor cell supernatant and 2×DMEM∶F12 was 1∶1

the expressions of α-SMA and TGF-β

1

(P=0.96

P=0.21) increased and reached the peak at the third day (P0.05)

after that time the α-SMA expression was sustained.       Conclusion       When the ratio of tumor cell supernatant in 2×DMEM∶F12 is 1∶1

the growth of fibroblasts and fibroblasts transformation into myofibroblasts could be effectively promoted.