Effects of Isoxazolyl Steroids on Key Genes of Sonic Hedgehog Cascade Expression in Tumor Cells

Activation of the Hedgehog (Hh) signaling pathway is often associated with the progression of various types of cancer. The purpose of study was to search for inhibitors of the Hh signaling pathway among eight compounds belonging to the group of isoxazolyl steroids. The evaluation of the effectiveness of the compounds was based on the analysis of their cytotoxicity, effect on the cell cycle, on the expression of key Hh-signaling-pathway genes (Ptch1, Smo, and Gli1) and putative target genes MMP-2 and MMP-9. Four compounds with the most pronounced cytotoxic effect were identified: compounds 1, 2 (HeLa cells) and 3, 4 (A549 cells). Compounds 1 and 2 significantly reduced the expression of the Ptch1, Smo, Gli1 genes, but had the opposite effect on MMP-2 gene expression: Compound 1 increased it, and compound 2 decreased it. Compounds 3 and 4 did not have a noticeable inhibitory effect on the expression of the Shh pathway receptors, but significantly inhibited MMP-2 and MMP-9 expression. Thus, it was shown that inhibition of the Shh signaling pathway by isoxazolyl steroids can have the opposite effect on MMPs gene expression, which is what should be taken into account in further studies of these compounds as therapeutic agents.