[Effect of Hedgehog Signaling Pathway Abnormality on Chemothe-rapeutic Resistance of Multiple Myeloma]

To study the correlation between the excessive activation of Hedgehog signal and the drug resistance of multiple myeloma.

The resistant cell line RPMI 8226/R of multiple myeloma was established by an ascending concentration gradient method. The experiment consisted of 4 groups: RPMI8226/R, RPMI8226/S, GANT61+RPMI8226/R and GANT61+RPMI8226/S. The CCK-8 (cell counting kit-8) assay was used to detect the cell proliferation inhibition rate in 4 groups; the RT-PCR was used to detect the expression of Gli1, Gli2, Shh, Ihh, Smo and Sufu in the RPMI8226/S and RPMI8226/R cells. The Western blot was used to detect the expression of the resistant protein Cyclin D1, P21 and BCL-2 and MDR-related signaling pathways protein p-Akt, p-MAPK and STAT3 in the RPMI8226/S and RPMI8226/R cells. After adding different concentration of GANT61, the Western blot was used to detect the expression of Gli2 in RPMI8226/R and RPMI8226/S cells.

The expression of Shh, Ihh, Smo Gli2 was enhanced significantly in the RPMI8226/R cells, but the expression of Sufu inhibitor was reduced, the expression level of related protein in Hedgehog signaling pathway was significanly higher in RPMI8226/R than that in RPMI8226/S. After theatment of GANT61 in vitro, the expression level of Gli2 in multiple myelom cells obviously decreased, the decreasing effect of GANT61 on Gli2 expression in RPMI8226/R cells was more significant than that in RPMI8226/S cells. The sensitivity of RPMI8226/R cells to DOX after treatment with GANT61 (IC₅₀) was risen from 7.11±0.061 µmol/L to 0.99±0.053 µmol/L, the corresponding cell resistance index decreased from 5.51 to 1.69.

the activation of Hedgehog signaling pathway is closely related with the resistance of multiple myeloma cells, and GANT61 can block the Hedgehog signaling pathway, thus Hedgehog signaling may be used as a new target for multiple myeloma treatment.