The carboxyl-terminal domain of the protein kinase fused can function as a dominant inhibitor of hedgehog signaling.

The secreted protein hedgehog (Hh) plays a critical role in the developmental patterning of multiple tissues. In Drosophila melanogaster, a cytosolic multiprotein signaling complex appears necessary for Hh signaling. Genes that encode components of this Hh signaling complex (HSC) were originally identified and characterized based on their genetic interactions with hh, as well as with each other.

Identification of a tetrameric hedgehog signaling complex.

Hedgehog (Hh) signal transduction requires a large cytoplasmic multi-protein complex that binds microtubules in an Hh-dependent manner. Here, we show that three members of this complex, Costal2 (Cos2), Fused (Fu), and Cubitus interruptus (Ci), bind each other directly to form a trimeric complex. We demonstrate that this trimeric signaling complex exists in Drosophila lacking Suppressor of Fused (Su(fu)), an extragenic suppressor of fu, indicating that Su(fu) is not required for the formation, or apparently function, of the Hh signaling complex.

Characterization of the intracellular distribution and binding in human adenocarcinoma cells of N-(4-azidophenylsulfonyl)-N'-(4-chlorophenyl)urea (LY219703), a photoaffinity analogue of the antitumor diarylsulfonylurea sulofenur.

A photoactivatable diarylsulfonylurea, N-(4-azidophenylsulfonyl)-N'-(4-chlorophenyl)urea (LY219703), has been examined as a potential probe to elucidate the intracellular distribution and binding of antitumor diarylsulfonylureas. Our results demonstrated that against the human colon adenocarcinoma cell line GC3/c1, LY219703 is a more potent cytotoxic agent than N-(5-indanylsulfonyl)-N'-(4-chlorophenyl)urea (Sulofenur; ISCU), whereas a subline selected for resistance to ISCU was cross-resistant to LY219703, suggesting a similar mechanism of action or resistance. Cellular pharmacology studies showed that [3H]LY219703 concentrated in cells, and that its concentrative accumulation could be inhibited by carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), thus indicating that it was similar to other antitumor diarylsulfonylurea (DSU) drugs examined.

Cross-resistance to antitumor diarylsulfonylureas and collateral sensitivity to mitochondrial toxins in a human cell line selected for resistance to the antitumor agent N-(5-indanylsulfonyl)-N'-(4-chlorophenyl)urea.

Diarylsulfonylurea (DSU) antitumor agents represent a new class of oncolytic compounds with an unknown, potentially novel, mechanism of action. At high concentrations of several of these agents, cytotoxicity appears to be a consequence of uncoupling of mitochondria. However, the mechanism of action at pharmacologically achievable concentrations is unknown.

Proliferation-dependent and -independent cytotoxicity by antitumor diarylsulfonylureas. Indication of multiple mechanisms of drug action.

The mechanism(s) by which antitumor diarylsulfonylureas (DSU) cause cytotoxicity has been examined in GC3/c1 human colon adenocarcinoma cells and a subline selected for resistance to N-(5-indanylsulfonyl)-N'-(4-chlorophenyl)urea (ISCU). Resistance was stable in the absence of selection pressure. This mutant (designated LYC5) was 5.