Transforming growth factor-\u3b21 is the predominant isoform required for breast cancer cell outgrowth in bone

Transforming growth factor (TGF)-\u3b2 signaling is a potent modulator of the invasive and metastatic behavior of breast cancer cells. Indeed, breast tumor responsiveness to TGF-\u3b2 is important for the development of osteolytic bone metastases. However, the specific TGF-\u3b2 isoforms that promote breast cancer outgrowth in bone is unknown. We demonstrate that expression of a TGF-\u3b2 ligand trap, which neutralizes TGF-\u3b21 and TGF-\u3b23, in MDA-MB-231 breast cancer cells diminished their outgrowth in bone and reduced the severity of osteolytic lesion formation when compared with controls. We further show that a reduction or loss of TGF-\u3b21 expression within the bone microenvironment of TGF-\u3b21+/- and TGF-\u3b21-/- mice significantly reduced the incidence of breast tumor outgrowth compared with wild-type animals. Interestingly, those tumors capable of growing within the tibiae of TGF-\u3b21- deficient mice had upregulated expression of all three TGF-\u3b2 isoforms. Finally, breast cancer cells expressing the TGF-\u3b2 ligand trap showed a pronounced reduction in their ability to form osteolytic lesions when injected into the tibiae of TGF-b1\ufe +/- mice. Thus, our studies show that both host- and tumor-derived TGF-\u3b2 expression plays a critical role during the establishment and outgrowth of breast cancer cells in bone.NRC publication: Ye

Localization of antigenic sites of the E2 glycoprotein of transmissible gastroenteritis coronavirus

Four antigenic sites of the E2 glycoprotein of transmissible gastroenteritis virus were defined by competitive radioimmunoassays of monoclonal antibodies (MAbs). Here, we describe the localization of these sites by testing the antigenicity of protein fragments and prokaryotic expression products of E2 gene fragments, and by sequencing of MAb-resistant (mar) mutants. Partial proteolysis of purified E2 protein allowed the isolation of a 28K fragment recognized by both site A- and site C-specific MAbs. An antiserum against this fragment bound to a synthetic peptide containing residues 1 to 18 and to an expression product containing residues 1 to 325. The same expression product was recognized by site C-specific MAbs. These data indicate that residues within the sequence 1 to 325 contribute to site C and possibly also to site A. Sequencing of mar mutants that escaped neutralization by site A-specific MAbs indicated that residues 538 and 543 also belong to site A. The binding of site-specific MAbs to expression products led directly to the localization of sites B and D, between residues 1 to 325 and 379 to 529, respectively. The first 37% of the polypeptide chain of E2 appears to be more immunogenic than the rest of the sequence

Localization of antigenic sites of the E2 glycoprotein of transmissible gastroenteritis coronavirus

Four antigenic sites of the E2 glycoprotein of transmissible gastroenteritis virus were defined by competitive radioimmunoassays of monoclonal antibodies (MAbs). Here, we describe the localization of these sites by testing the antigenicity of protein fragments and prokaryotic expression products of E2 gene fragments, and by sequencing of MAb-resistant (mar) mutants. Partial proteolysis of purified E2 protein allowed the isolation of a 28K fragment recognized by both site A- and site C-specific MAbs. An antiserum against this fragment bound to a synthetic peptide containing residues 1 to 18 and to an expression product containing residues 1 to 325. The same expression product was recognized by site C-specific MAbs. These data indicate that residues within the sequence 1 to 325 contribute to site C and possibly also to site A. Sequencing of mar mutants that escaped neutralization by site A-specific MAbs indicated that residues 538 and 543 also belong to site A. The binding of site-specific MAbs to expression products led directly to the localization of sites B and D, between residues 1 to 325 and 379 to 529, respectively. The first 37% of the polypeptide chain of E2 appears to be more immunogenic than the rest of the sequence

Analysis of tumor heterogeneity and cancer gene networks using deep sequencing of MMTV-induced mouse mammary tumors

Cancer develops through a multistep process in which normal cells progress to malignant tumors via the evolution of their genomes as a result of the acquisition of mutations in cancer driver genes. The number, identity and mode of action of cancer driver genes, and how they contribute to tumor evolution is largely unknown. This study deployed the Mouse Mammary Tumor Virus (MMTV) as an insertional mutagen to find both the driver genes and the networks in which they function. Using deep insertion site sequencing we identified around 31000 retroviral integration sites in 604 MMTV-induced mammary tumors from mice with mammary gland-specific deletion of Trp53, Pten heterozygous knockout mice, or wildtype strains. We identified 18 known common integration sites (CISs) and 12 previously unknown CISs marking new candidate cancer genes. Members of the Wnt, Fgf, Fgfr, Rspo and Pdgfr gene families were commonly mutated in a mutually exclusive fashion. The sequence data we generated yielded also information on the clonality of insertions in individual tumors, allowing us to develop a data-driven model of MMTV-induced tumor development. Insertional mutations near Wnt and Fgf genes mark the earliest ‘‘initiating’’ events in MMTV induced tumorigenesis, whereas Fgfr genes are targeted later during tumor progression. Our data shows that insertional mutagenesis can be used to discover the mutational networks, the timing of mutations, and the genes that initiate and drive tumor evolution.Computer ScienceElectrical Engineering, Mathematics and Computer Scienc