Mediators of hedgehog signaling pathways, compositions and uses related thereto

#Pattern formation is the activity by which embryonic cells form ordered spatial arrangements of differentiated tissues. The physical complexity of higher organisms arises during embryogenesis through the interplay of cell-intrinsic lineage and cell-extrinsic signaling. Inductive interactions are essential to embryonic patterning in vertebrate development from the earliest establishment of the body plan, to the patterning of the organ systems, to the generation of diverse cell types during tissue differentiation (Davidson, E., (1990) Development 108: 365-389; Gurdon, J. B., (1992) Cell 68: 185-199; Jessell, T. M. et al., (1992) Cell 68: 257-270). The effects of developmental cell interactions are varied. Typically, responding cells are diverted from one route of cell differentiation to another by inducing cells that differ from both the uninduced and induced states of the responding cells (inductions). Sometimes cells induce their neighbors to differentiate like themselves (homeogenetic induction); in other cases a cell inhibits its neighbors from differentiating like itself. Cell interactions in early development may be sequential, such that an initial induction between two cell types leads to a progressive amplification of diversity. Moreover, inductive interactions occur not only in embryos, but in adult cells as well, and can act to establish and maintain morphogenetic patterns as well as induce differentiation (J. B. Gurdon (1992) Cell 68:185-199).

#Members of the Hedgehog family of signaling molecules mediate many important short- and long-range patterning processes during invertebrate and vertebrate development. In the fly, a single hedgehog gene regulates segmental and imaginal disc patterning. In contrast, in vertebrates, a hedgehog gene family is involved in the control of left-right asymmetry, polarity in the CNS, somites and limb, organogenesis, chondrogenesis and spermatogenesis.

#The first hedgehog gene was identified by a genetic screen in the fruitfly Drosophila melanogaster (Nüsslein-Volhard, C. and Wieschaus, E. (1980) Nature 287, 795-801). This screen identified a number of mutations affecting embryonic and larval development. In 1992 and 1993, the molecular nature of the Drosophila hedgehog (hh) gene was reported (C F., Lee et al. (1992) Cell 71, 33-50), and since then, several hedgehog homologues have been isolated from various vertebrate species. While only one hedgehog gene has been found in Drosophila and other invertebrates, multiple Hedgehog genes are present in vertebrates.

#FIGS. 1-31 depict reactions useful for synthesizing compounds according to the present invention.

#FIGS. 32a-o illustrates representative compounds according to the present invention.

#FIG. 33A shows gli-1 mRNA expression in cells treated with vehicle (Lane 1); 5 μM jervine, the positive control compound (Lane 2); and 1 μM D (Lane 3). Compared with vehicle, D and jervine significantly decreased the expression of gli-1 mRNA.

#The present invention relates to the discovery that signal transduction pathways regulated by hedgehog, patched (ptc), gli and/or smoothened can be inhibited, at least in part, by small molecules. While not wishing to bound by any particular theory, the activation of a receptor may be the mechanism by which these agents act. For example, the ability of these agents to inhibit proliferation of patched loss-of-function (ptclof) cells may be due to the ability of such molecules to interact with hedgehog, patched, or smoothened, or at least to interfere with the ability of those proteins to activate a hedgehog, ptc, and/or smoothened-mediated signal transduction pathway.

#It is, therefore, specifically contemplated that these small molecules which intefere with aspects of hedgehog, ptc, or smoothened signal transduction activity will likewise be capable of inhibiting proliferation (or other biological consequences) in normal cells and/or cells having a patched loss-of-function phenotype, a hedgehog gain-of-function phenotype, or a smoothened gain-of-function phenotype. Thus, it is contemplated that in certain embodiments, these compounds may be useful for inhibiting hedgehog activity in normal cells, e.g., which do not have a genetic mutation that activates the hedgehog pathway. In preferred embodiments, the subject inhibitors are organic molecules having a molecular weight less than 2500 amu, more preferably less than 1500 amu, and even more preferably less than 750 amu, and are capable of inhibiting at least some of the biological activities of hedgehog proteins, preferably specifically in target cells.

#Thus, the methods of the present invention include the use of small molecules which agonize ptc inhibition of hedgehog signalling, such as by inhibiting activation of smoothened or downstream components of the signal pathway, in the regulation of repair and/or functional performance of a wide range of cells, tissues and organs, including normal cells, tissues, and organs, as well as those having the phenotype of ptc loss-of-function, hedgehog gain-of-function, or smoothened gain-of-function. For instance, the subject method has therapeutic and cosmetic applications ranging from regulation of neural tissues, bone and cartilage formation and repair, regulation of spermatogenesis, regulation of smooth muscle, regulation of lung, liver and other organs arising from the primative gut, regulation of hematopoietic function, regulation of skin and hair growth, etc. Moreover, the subject methods can be performed on cells which are provided in culture (in vitro), or on cells in a whole animal (in vivo). See, for example, PCT publications WO 95/18856 and WO 96/17924 (the specifications of which are expressly incorporated by reference herein).