CD44 enhances tumor formation and lung metastasis in experimental osteosarcoma and is an additional predictor for poor patient outcome

Formation of metastases in the lungs is the major cause of death in patients suffering from osteosarcoma (OS). Metastases at presentation and poor response to preoperative chemotherapy are strong predictors for poor patient outcome. The elucidation of molecular markers that promote metastasis formation and/or chemoresistance is therefore of importance. CD44 is a plasma membrane glycoprotein that binds to the extracellular matrix component hyaluronan (HA) and has been shown to be involved in metastasis formation in a variety of other tumors. Here we investigated the role of CD44 expression on OS tumor formation and metastasis. High CD44 expression, evaluated with a tissue microarray including samples from 53 OS patients and stained with a pan‐CD44 antibody (Hermes3), showed a tendency (p < 0.08) to shortened overall survival. However, nonresponders and patients with lung metastases and high CD44 expression had significantly poorer prognosis than patients with low CD44 expression. Overexpression of the standard CD44 isoform (CD44s) and its HA‐binding defective mutant R41A in osteoblastic SaOS‐2 cells resulted in HA‐independent higher migration rates and increased chemoresistance, partially dependent on HA. In an orthotopic mouse model of OS, overexpression of CD44s in SaOS‐2 cells resulted in an HA‐dependent increased primary tumor formation and increased numbers of micrometastases and macrometastases in the lungs. In conclusion, although CD44 failed to be an independent predictor for patient outcome in this limited cohort of OS patients, increased CD44 expression was associated with even worse survival in patients with chemoresistance and with lung metastases. CD44‐associated chemoresistance was also observed in vitro, and increased formation of lung metastases was found in vivo in SCID mice. © 2013 American Society for Bone and Mineral Research.     

Expression of bcr-abl abrogates factor-dependent growth of human hematopoietic M07E cells by an autocrine mechanism

The introduction of a retrovirus vector expressing p210bcr-abl (P210) into the human factor-dependent cell line M07E resulted in the rapid outgrowth of factor-independent cells. Early after infection, four factor-independent clones were isolated and analyzed in greater detail along with mass populations obtained from separate infections. High levels of P210 tyrosine kinase activity were measured in the factor- independent cells. The mass populations and three of the four clones remained responsive to exogenous growth factors. Concentrated conditioned media isolated from the factor-independent populations and from all clones contained biologically active granulocyte-macrophage colony-stimulating factor (GM-CSF); interleukin-3 (IL-3) was detected at low levels in the mass population and in two of the clones. Neutralizing antibodies to IL-3, GM-CSF, and mast cell growth factor inhibited proliferation of the factor responsive clones by 60% to 90%. These results indicate that the growth autonomy of the P210-expressing M07E cells was acquired via an autocrine mechanism. In addition to factor-independent growth, P210-expressing M07E cells readily acquired a more mature megakaryocytic phenotype compared with control M07E cells. These data provide experimental evidence that expression of P210 tyrosine kinase in human hematopoietic cells induced growth factor secretion resulting in a pleiotropic effect on growth factor dependence and differentiation.     

Airway intervention in adult supraglottitis

Background The timing of aggressive airway intervention in adult epiglottitis is controversial. Aims To correlate Friedman’s staging of epiglottitis on admission with the airway interventions undertaken. Methods A retrospective study of 23 adult patients, mean age 51 years (range 29–81 years), who had been admitted with acute supraglottitis between March 1988 and December 2000 was undertaken. Results Three patients (13%) had airway interventions; two with tracheostomy and one with tracheal intubation. All were Friedman stage III and had rapid symptom progression during the 24 hours prior to admission. Three other stage III patients with symptom progression longer than 24 hours and all the remaining patients (stage II or less) were managed with observation and intravenous therapy. Conclusions Friedman originally advocated airway intervention in any patient stage II or worse, but this intubation threshold should probably be lowered to those patients with rapid-onset stage III (moderate respiratory distress, stridor, respiratory rate >30 per minute, pCO₂ >45mmHg) disease.     

The hematopoietic stem cells of alpha-thalassemic mice

The alpha-thalassemic mouse has a hereditary microcytic anemia, almost certainly has a shortened RBC life span, and is a potential candidate for cell replacement therapy. In a routine study of bone marrow repopulating capacity using hemoglobin as a cell marker, normal donor marrow cells, but not alpha-thalassemic donor marrow cells, completely replaced the host cells. Further analysis showed that at least 30 times more alpha-thalassemic cells were required to outcompete normal donor cells injected simultaneously. The results were more extreme then expected and suggested a defect in a stem cell population as well as in the RBCs. Evidence that the multipotent and erythroid-committed stem cells in alpha-thalassemic mice are not decreased was shown by CFU-S and CFU-E assays. The combined results indicate that the deletion expresses itself most conspicuously in the RBC population. Tests were also performed to analyze repopulation kinetics in the Hbath-J/+ mice. In unirradiated alpha-thalassemic hosts, the hemoglobin from a normal donor persisted but did not replace the host hemoglobin. Sublethally irradiated alpha-thalassemic hosts, on the other hand, were easily repopulated with normal cells. We conclude that the alpha-thalassemic mouse is a good model for cell replacement therapy.     

A longitudinal study of otitis media with effusion among 2- to 5-year-old African-American children in child care

OBJECTIVE: To prospectively document the prevalence of otitis media with effusion (OME) in 86 African-American children between ages 2 and 5 years. STUDY DESIGN: Eighty-six children in center-based child care whose ear status had been followed from infancy continued to be observed. Middle ear status was assessed by pneumatic otoscopy and tympanometry biweekly. RESULTS: The prevalence of OME decreased as children became older. The mean proportion of examinations demonstrating bilateral OME (BOME) ranged from 12% between 24 to 30 months to 4% between 54 to 60 months of age. The mean proportion of exams revealing bilateral normal ears increased from 77% at 24 to 30 months to 88% at 54 to 60 months of age. Although 60 children had experienced BOME that lasted 4 months or longer in the 6- to 24-month age period, only 8 of these children experienced at least 4 months of continuous BOME between 24 to 60 months. CONCLUSIONS: The proportion of time with BOME decreased progressively with increasing age in this population. Only 8 of 60 children who had experienced more than 4 consecutive months of BOME before 2 years of age continued to manifest persistent effusion or experience recurrences of prolonged BOME after 2 years of age.