Low level of Fibrillarin, a ribosome biogenesis factor, is a new independent marker of poor outcome in breast cancer.

BACKGROUND: A current critical need remains in the identification of prognostic and predictive markers in early breast cancer. It appears that a distinctive trait of cancer cells is their addiction to hyperactivation of ribosome biogenesis. Thus, ribosome biogenesis might be an innovative source of biomarkers that remains to be evaluated. METHODS: Here, fibrillarin (FBL) was used as a surrogate marker of ribosome biogenesis due to its essential role in the early steps of ribosome biogenesis and its association with poor prognosis in breast cancer when overexpressed. Using 3,275 non-metastatic primary breast tumors, we analysed FBL mRNA expression levels and protein nucleolar organisation. Usage of TCGA dataset allowed transcriptomic comparison between the different FBL expression levels-related breast tumours. RESULTS: We unexpectedly discovered that in addition to breast tumours expressing high level of FBL, about 10% of the breast tumors express low level of FBL. A correlation between low FBL mRNA level and lack of FBL detection at protein level using immunohistochemistry was observed. Interestingly, multivariate analyses revealed that these low FBL tumors displayed poor outcome compared to current clinical gold standards. Transcriptomic data revealed that FBL expression is proportionally associated with distinct amount of ribosomes, low FBL level being associated with low amount of ribosomes. Moreover, the molecular programs supported by low and high FBL expressing tumors were distinct. CONCLUSION: Altogether, we identified FBL as a powerful ribosome biogenesis-related independent marker of breast cancer outcome. Surprisingly we unveil a dual association of the ribosome biogenesis FBL factor with prognosis. These data suggest that hyper- but also hypo-activation of ribosome biogenesis are molecular traits of distinct tumors.

Association between FGFR1 copy numbers, MAP3K1 mutations, and survival in axillary node-positive, hormone receptor-positive, and HER2-negative early breast cancer in the PACS04 and METABRIC studies.

PURPOSE: Hormone receptor-positive (HR+) and human epidermal growth factor receptor 2 negative (HER2-) early breast cancer (BC) is the most prevalent BC subtype with substantial biological heterogeneity. Although clinicopathological (CP) characteristics have a clear prognostic value, additional biomarkers could refine survival prediction and guide treatment decision. METHODS: Copy number aberrations and somatic driver mutations were obtained with OncoScan CGH array and sequencing of 36 genes on HR+/HER2- node-positive early BC patients treated with chemotherapy from the PACS04 trial. We built a two-gene genomic score (GS) associated with distant disease-free survival (DDFS), whose prognostic value was assessed on the external METABRIC data (n = 1413) using overall survival (OS) and breast cancer-specific survival (BCSS). RESULTS: In the PACS04 trial (n = 327), the median follow-up for DDFS (65 events) was 9.6 years. FGFR1 amplifications ([Formula: see text] = 2.44, 95% CI [1.25; 4.76], p = 0.009) and MAP3K1 mutations ([Formula: see text] = 0.10, [0.01; 0.78], p = 0.03) were associated with DDFS beyond CP characteristics. A prognostic GS combining FGFR1 amplifications and MAP3K1 mutations added more information to CP model ([Formula: see text] = 12.97, [Formula: see text] < 0.001 and [Formula: see text] = 11.52, [Formula: see text] < 0.001). In the METABRIC study (n = 1413), FGFR1 amplifications ([Formula: see text] = 2.00 [1.40; 2.87], p < 0.001) and MAP3K1 mutations ([Formula: see text] = 0.58 [0.41; 0.83], p = 0.003) were significantly associated with BCSS beyond CP characteristics. The prognostic GS added significant prognostic information to CP model ([Formula: see text] = 15.39, [Formula: see text] < 0.001 and [Formula: see text] = 5.62, [Formula: see text] = 0.02). CONCLUSION: In axillary node-positive, HR+, and HER2- early BC, amplifications of FGFR1 gene were strongly associated with increased risk for distant disease, while mutations of MAP3K1 gene were significantly associated with decreased risk.

CYR61 triggers osteosarcoma metastatic spreading via an IGF1Rß-dependent EMT-like process.

BACKGROUND: Osteosarcoma is the most prevalent primary bone malignancy in children and young adults. These tumors are highly metastatic, leading to poor outcome. We previously demonstrated that Cysteine-rich protein 61 (CYR61/CCN1) expression level is correlated to osteosarcoma aggressiveness in preclinical model and in patient tumor samples. The aim of the present study was to investigate the CYR61-induced intracellular mechanisms leading to the acquisition of an invasive phenotype by osteosarcoma cells. METHODS: Modified murine and human osteosarcoma cell lines were evaluated for cell adhesion, aggregation (spheroid), motility (wound healing assay), phenotypic markers expression (RT-qPCR, western blot). Cell-derived xenograft FFPE samples and patients samples (TMA) were assessed by IHC. RESULTS: CYR61 levels controlled the expression of markers related to an Epithelial-mesenchymal transition (EMT)-like process, allowing tumor cells to migrate acquiring a competent morphology, and to be able to invade the surrounding stroma. This phenotypic shift indeed correlated with tumor grade and aggressiveness in patient samples and with the metastatic dissemination potential in cell-derived xenograft models. Unlike EGFR or PDGFR, IGF1Rß levels correlated with CYR61 and N-cadherin levels, and with the aggressiveness of osteosarcoma and overall survival. The expression levels of IGF1Rß/IGF1 axis were controlled by CYR61, and anti-IGF1 neutralizing antibody prevented the CYR61-induced phenotypic shift, aggregation, and motility abilities. CONCLUSIONS: Taken together, our study provides new evidence that CYR61 acts as a key inducing factor in the metastatic progression of osteosarcoma by playing a critical role in primary tumor dissemination, with a process associated with IGF1/IGFR stimulation. This suggests that CYR61 may represent a potential pivotal target for therapeutic management of metastases spreading in osteosarcoma, in correlation with IGF1/IGFR pathway.