Targeted inactivation of murine laminin gamma2-chain gene recapitulates human junctional epidermolysis bullosa.

Junctional forms of epidermolysis bullosa (JEB) are associated with mutations in six distinct genes expressed in the cutaneous basement membrane zone; these include LAMA3, LAMB3, and LAMC2, which encode laminin 5 subunit polypeptides, the alpha3-, beta3-, and gamma2-chains, respectively. Here we generated a mouse model for JEB by inactivating the laminin gamma2-chain gene by targeted frameshift deletion of exon 8 in Lamc2. Heterozygous mice were phenotypically normal, whereas the majority of Lamc2-/- mice showed blistering phenotype on days 1 to 2 and died within 5 days of birth. The Lamc2-/- mice demonstrated absent expression of laminin gamma2-chain on the basement membrane zone as well as attenuated expression of alpha3- and beta3-chains of laminin. Transmission electron microscopy revealed rudimentary, poorly developed hemidesmosomes. The epidermis of the Lamc2-/- mice revealed induced apoptosis in the basal cells of the blistered skin, suggesting that cell-matrix adhesion provided by laminin 5 plays a role in cell survival in vivo. Cultured Lamc2-/- keratinocytes demonstrated slightly positive staining with gamma2-chain-specific antibodies, which could be explained by the presence of a transcript with partial restoration of the reading frame owing to alternative splicing in vitro. These cells proliferated in different matrices and attached to type IV collagen and Matrigel as efficiently as the wild-type keratinocytes, whereas their attachment on plastic and laminin was significantly weaker. In summary, Lamc2-/- mouse recapitulates human JEB and provides novel insight into the role of laminin 5 in keratinocyte biology.

GSK1838705A inhibits the insulin-like growth factor-1 receptor and anaplastic lymphoma kinase and shows antitumor activity in experimental models of human cancers.

The insulin-like growth factor-I receptor (IGF-IR) signaling pathway is activated in various tumors, and inhibition of IGF-IR kinase provides a therapeutic opportunity in these patients. GSK1838705A is a small-molecule kinase inhibitor that inhibits IGF-IR and the insulin receptor with IC(50)s of 2.0 and 1.6 nmol/L, respectively. GSK1838705A blocks the in vitro proliferation of cell lines derived from solid and hematologic malignancies, including multiple myeloma and Ewing's sarcoma, and retards the growth of human tumor xenografts in vivo. Despite the inhibitory effect of GSK1838705A on insulin receptor, minimal effects on glucose homeostasis were observed at efficacious doses. GSK1838705A also inhibits the anaplastic lymphoma kinase (ALK), which drives the aberrant growth of anaplastic large-cell lymphomas, some neuroblastomas, and a subset of non-small cell lung cancers. GSK1838705A inhibits ALK, with an IC(50) of 0.5 nmol/L, and causes complete regression of ALK-dependent tumors in vivo at well-tolerated doses. GSK1838705A is therefore a promising antitumor agent for therapeutic use in human cancers.