Wnt signaling and Loxl2 promote aggressive osteosarcoma

Osteosarcoma (OS) is the most frequent primary malignant bone tumor in urgent need of better therapies. Using genetically modified mouse models (GEMMs), we demonstrate that Wnt signaling promotes c-Fos-induced OS formation via the actions of the collagen-modifying enzyme Loxl2. c-Fos/AP-1 directly regulates the expression of the Wnt ligands Wnt7b and Wnt9a in OS cells through promoter binding, and Wnt7b and Wnt9a in turn promote Loxl2 expression in murine and human OS cells through the transcription factors Zeb1 and Zeb2. Concordantly, inhibition of Wnt ligand secretion by inactivating the Wnt-less (Wls) gene in osteoblasts in c-Fos GEMMs either early or in a therapeutic setting reduces Loxl2 expression and progression of OS. Wls-deficient osteosarcomas proliferate less, are less mineralized and are enriched in fibroblastic cells surrounded by collagen fibers. Importantly, Loxl2 inhibition using either the pan-Lox inhibitor BAPN or a specific inducible shRNA reduces OS cell proliferation in vitro and decreases tumor growth and lung colonization in murine and human orthotopic OS transplantation models. Finally, OS development is delayed in c-Fos GEMMs treated with BAPN or with specific Loxl2 blocking antibodies. Congruently, a strong correlation between c-FOS, LOXL2 and WNT7B/WNT9A expression is observed in human OS samples, and c-FOS/LOXL2 coexpression correlates with OS aggressiveness and decreased patient survival. Therefore, therapeutic targeting of Wnt and/or Loxl2 should be considered to potentiate the inadequate current treatments for pediatric, recurrent, and metastatic OS

Wnt signaling and Loxl2 promote aggressive osteosarcoma

Osteosarcoma (OS) is the most frequent primary malignant bone tumor in urgent need of better therapies. Using genetically modified mouse models (GEMMs), we demonstrate that Wnt signaling promotes c-Fos-induced OS formation via the actions of the collagen-modifying enzyme Loxl2. c-Fos/AP-1 directly regulates the expression of the Wnt ligands Wnt7b and Wnt9a in OS cells through promoter binding, and Wnt7b and Wnt9a in turn promote Loxl2 expression in murine and human OS cells through the transcription factors Zeb1 and Zeb2. Concordantly, inhibition of Wnt ligand secretion by inactivating the Wnt-less (Wls) gene in osteoblasts in c-Fos GEMMs either early or in a therapeutic setting reduces Loxl2 expression and progression of OS. Wls-deficient osteosarcomas proliferate less, are less mineralized and are enriched in fibroblastic cells surrounded by collagen fibers. Importantly, Loxl2 inhibition using either the pan-Lox inhibitor BAPN or a specific inducible shRNA reduces OS cell proliferation in vitro and decreases tumor growth and lung colonization in murine and human orthotopic OS transplantation models. Finally, OS development is delayed in c-Fos GEMMs treated with BAPN or with specific Loxl2 blocking antibodies. Congruently, a strong correlation between c-FOS, LOXL2 and WNT7B/WNT9A expression is observed in human OS samples, and c-FOS/LOXL2 coexpression correlates with OS aggressiveness and decreased patient survival. Therefore, therapeutic targeting of Wnt and/or Loxl2 should be considered to potentiate the inadequate current treatments for pediatric, recurrent, and metastatic OS

Multiplexed Assessment of the Southwest Oncology Group-Directed Intergroup Breast Cancer Trial S9313 by AQUA Shows that Both High and Low Levels of HER2 Are Associated with Poor Outcome

Assessment of key breast cancer tissue biomarkers is often done using nonquantitative methods. We hypothesized that use of continuous analysis of expression with the AQUA method of automated quantitative analysis will provide prognostic information beyond that attainable with conventional methods. A tissue microarray was made from 2123 of 3122 patients accrued to SWOG 9313, in which sequential doxorubicin (A) and cyclophosphamide (C) was compared with combination AC and in which all patients except premenopausal estrogen receptor (ER)-negative patients received tamoxifen. Multiplexed assays of 1) HER2 and estrogen receptor and 2) progesterone receptor (PgR) and p53 were performed on the two slides using the immunofluorescence-based AQUA method of automated quantitative analysis. Both ER and PgR showed unimodal distributions and significantly predicted disease-free survival when tested as continuous variables and adjusted for node status, tumor size, treatment, and menopausal status (P = 0.005 and P < 0.001, respectively). HER2, measured as a continuous variable, showed a biphasic effect on disease-free survival. Both high and low expressers of HER2 have worse outcomes (when low levels are equivalent to that seen in normal breast ducts). In patients who were uniformly treated with AC chemotherapy and tamoxifen (when indicated), both ER and PgR, assessed as continuous variables, were highly prognostic, whereas p53 expression was not. This assay method may provide a new companion diagnostic approach for targeted therapies