Direct and immune mediated antibody targeting of ERBB receptors in a colorectal cancer cell-line panel.

A significant proportion of colorectal cancer (CRC) patients are resistant to anti-ERBB1 [avian erythroblastic leukemia viral (v-erb-b) oncogene homolog, receptor for EGF] monoclonal antibodies (Mabs). We evaluated both immune and nonimmune effects of cetuximab (anti-ERBB1 Mab), trastuzumab (anti-ERBB2 Mab), pertuzumab (anti-ERBB2 Mab), and lapatinib (dual ERBB1 and ERBB2 tyrosine kinase inhibitor) in a large well-characterized panel of 64 CRC cell lines to find response predictive tumor characteristics. There was a significant correlation between the direct effects of cetuximab and lapatinib. Both agents were associated (P = 0.0004) with "triple' wild-type status in KRAS, BRAF, and PIK3CA exon 20. Most cell lines were resistant to the direct effects of anti-ERBB2 Mabs, suggesting that the effects of lapatinib might mainly be through ERBB1. Microarray mRNA expression profiles of sensitive and resistant cell lines showed that although ERBB1 receptor or ligand levels did not associate with cetuximab sensitivity, high levels of ERBB2 (P = 0.036) and amphiregulin (P = 0.026) predicted sensitivity to lapatinib. However, higher ERBB1 expression predicted susceptibility to cetuximab-induced antibody-dependent cellular cytotoxicity and occurred independently of KRAS/BRAF/PIK3CA mutations (P = 0.69). Lapatinib may be an effective alternative therapy to cetuximab in triple wild-type tumors. Microarray analysis provides suggestive biomarkers for resistance. ERBB1 levels, independent of mutation status, predict immune killing. Therefore, anti-ERBB1 antibodies may be considered in CRC tumors with higher ERBB1 expression and favorable FcγR polymorphisms.

Cloning and functional characterization of the ovine Hormone Sensitive Lipase (HSL) full-length cDNAs: an integrated approach.

Hormone Sensitive Lipase (HSL) is a highly regulated enzyme that mediates lipolysis in adipocytes. HSL enzymatic activity is increased by adrenergic agonists, such as catecholamines and glucagons, which induce cyclic AMP (cAMP) intracellular production, subsequently followed by the activation of Protein Kinase A (PKA) and its downstream signalling cascade reactions. Since HSL constitutes the key enzyme in the regulation of lipid stores and the only enzyme being subjected to hormonal regulation [in terms of the recently identified Adipose Triglyceride Lipase (ATGL)], the ovine Hormone Sensitive Lipase (ovHSL) full-length cDNA clones were isolated, using a Polymerase Chain Reaction-based (PCR) strategy. The two isolated isoforms ovHSL-A and ovHSL-B contain two highly homologous Open Reading Frame (ORF) regions of 2.089 Kb and 2.086 Kb, respectively, the latter having been missed the 688th triplet coding for glutamine (DeltaQ(688)). The putative 695 and 694 amino acid respective sequences bear strong homologies with other HSL protein family members. Southern blotting analysis revealed that HSL is represented as a single copy gene in the ovine genome, while Reverse Transcription-PCR (RT-PCR) approaches unambiguously dictated its variable transcriptional expression profile in the different tissues examined. Interestingly, as undoubtedly corroborated by both RT-PCR and Western blotting analysis, ovHSL gene expression is notably enhanced in the adipose tissue during the fasting period, when lipolysis is highly increased in ruminant species. Based on the crystal structure of an Archaeoglobus fulgidus enzyme, a three-dimensional (3D) molecular model of the ovHSL putative catalytic domain was constructed, thus providing an inchoative insight into understanding the enzymatic activity and functional regulation mechanisms of the ruminant HSL gene product(s).