Disruption of protocadherin function as an indicator of cancer progression.

e21159 Background: Protocadherins (PCDH) are a large family of calcium-dependent cell–cell adhesion molecules that are involved in tissue morphogenesis, in particular the development of the central nervous system. Recently, alteration of PCDH alpha/beta/gamma locus genes have been implicated in a number of oncogenic processes: hypermethylation of the PCDH locus in Wilms’ tumor progression and metastasis, differential expression of some PCDH genes between bone and brain metastases in breast cancer patients, and epigenetic silencing of PCDH gamma A11 in astrocytoma invasion of the adjacent parenchyma. Assessment of PCDH function could help guide treatment decisions by aiding in the identification of cancer patients who are more likely to develop metastases. Methods: Identification of altered PCDH locus genes in cancer patient samples was performed using the NextBio platform which incorporates curated public genomic data from numerous sources, including TCGA, GEO, COSMIC, and others. Correlation of numerous data types was used to identify deleterious mutations, altered RNA expression, and copy number changes that were indicative of metastasis or a more advanced disease state. Results: A nearly 3-fold increase in the frequency of potentially detrimental somatic mutations in the PCDH gamma locus was observed in breast and ovarian cancer patients with extensive lymph node metastases (N3) compared to patients with a lower degree of lymph node metastasis (N0-N2). Similarly, expression of PCDH locus genes was down-regulated in cases of lymphoma, in metastatic samples across a number of diseases, and in diseases that commonly result in lymph node metastases including breast and lung cancer. Conclusions: Stratification of patient subgroups based on molecular signatures has become increasingly important for both assigning patients to appropriate clinical trials as well as providing insight into effective treatment options. Examination of PCDH perturbations may provide insight into a patient’s risk of developing a metastatic disease, in particular metastases to lymph nodes, and help identify patients who may benefit from a more aggressive treatment regimen.

MUC1 dysregulation as the consequence of a t(1;14)(q21;q32) translocation in an extranodal lymphoma

Cytogenetic abnormalities at chromosome 1q21 are among the most common lesions in diffuse large-cell lymphoma and have been associated with a poor prognosis. A novel cell line, SKI-DLCL-1, was established from ascitic fluid that carries a t(1;14)(q21;q32) chromosomal translocation. Using pulsed-field gel electrophoresis, the breakpoint on the IgH locus mapped to a gamma locus between C1 and C2. A cosmid library was prepared from SKI-DLCL-1, and Cγ-positive clones spanning the breakpoint were identified by screening with fluorescence in situ hybridization. The breakpoint occurs 860 bp downstream of the 3′ UTR of the MUC1 gene. The break appears to be a staggered double-strand break consistent with an error in immunoglobulin class switching. The MUC1 gene is highly transcribed and translated, and the protein is highly glycosylated. It is postulated that MUC1 expression is brought under the control of the 3′E enhancer. MUC1 lies in a region of chromosome 1 characterized by an unusually high density of genes, with 7 known genes in a region of approximately 85 kb. To determine whether there was a pleiotropic effect of the expression of genes in the region as a consequence of the translocation, the expression of 6 additional genes was assessed. None of the other genes in this region (CLK2, propin, COTE1, GBA, metaxin, and thrombospondin 3) are overexpressed in SKI-DLCL-1. Thus, the translocation t(1;14)(q21;q32) seen in both the primary tumor and the derived cell line results in the marked overexpression of MUC1 without affecting the expression of other genes in the region.

Viral Load and a Locus on Chromosome 11 Affect the Late Clinical Disease Caused by Theiler’s Virus

ABSTRACT Theiler’s virus causes a persistent infection and a demyelinating disease of mice which is a model for multiple sclerosis. Susceptibility to viral persistence maps to several loci, including the interferon gamma locus. Inactivating the gene coding for the interferon gamma receptor makes 129/Sv mice susceptible to persistent infection and clinical disease, whereas inactivating the interferon gamma gene makes C57BL/6 mice susceptible to persistent infection but not to clinical disease. This difference in phenotype is due to the difference in genetic background. Clinical disease depends on high viral load andTmevd5, a locus on chromosome 11. These results have consequences for the identification of viruses which might be implicated in multiple sclerosis.

Erythropoietin induces activation of Stat5 through association with specific tyrosines on the receptor that are not required for a mitogenic response.

The cytoplasmic domain of the erythropoietin receptor (EpoR) contains a membrane-distal region that is dispensable for mitogenesis but is required for the recruitment and tyrosine phosphorylation of a variety of signaling proteins. The membrane-proximal region of 96 amino acids is necessary and sufficient for mitogenesis as well as Jak2 activation, induction of c-fos, c-myc, cis, the T-cell receptor gamma locus (TCR-gamma), and c-pim-1. The studies presented here demonstrate that this region is also necessary and sufficient for the activation of Stat5A and Stat5B. The membrane-proximal domain contains a single tyrosine, Y-343, which when mutated eliminates the ability of the receptor to couple Epo binding to the activation of Stat5. Furthermore, peptide competitions demonstrate that this site, when phosphorylated, can disrupt Stat5 DNA binding activity, consistent with a role of Y-343 as a site of recruitment to the receptor. Cells expressing the truncated, Y343F mutant (a mutant with a Y-to-F alteration at position 343) proliferate in response to Epo in a manner comparable to that of the controls. However, in these cells, Epo stimulation does not induce the appearance of transcripts for cis, TCR-gamma, or c-fos, suggesting a role for Stat5 in their regulation.