Clinical value of R-spondins in triple-negative and metaplastic breast cancers.

BACKGROUND: RSPO ligands, activators of the Wnt/ß-catenin pathway, are overexpressed in different cancers. The objective of this study was to investigate the role of RSPOs in breast cancer (BC). METHODS: Expression of RSPO and markers of various cancer pathways were measured in breast tumours and cell lines by qRT-PCR. The effect of RSPO on the Wnt/ß-catenin pathway activity was determined by luciferase assay, western blotting, and qRT-PCR. The effect of RSPO2 inhibition on proliferation was determined by using RSPO2 siRNAs. The effect of IWR-1, an inhibitor of the Wnt/ß-catenin pathway, was examined on the growth of an RSPO2-positive patient-derived xenograft (PDX) model of metaplastic triple-negative BC. RESULTS: We detected RSPO2 and RSPO4 overexpression levels in BC, particularly in triple-negative BC (TNBC), metaplastic BC, and triple-negative cell lines. Various mechanisms could account for this overexpression: presence of fusion transcripts involving RSPO, and amplification or hypomethylation of RSPO genes. Patients with RSPO2-overexpressing tumours have a poorer metastasis-free survival (P=3.6 × 10-4). RSPO2 and RSPO4 stimulate Wnt/ß-catenin pathway activity. Inhibition of RSPO expression in a TN cell line inhibits cell growth, and IWR-1 significantly inhibits the growth of an RSPO2-overexpressing PDX. CONCLUSIONS: RSPO overexpression could therefore be a new prognostic biomarker and therapeutic target for TNBC.

A short-term colorectal cancer sphere culture as a relevant tool for human cancer biology investigation.

BACKGROUND: Ex vivo colospheres have been previously characterised as a colorectal cancer (CRC) well-rounded multicellular model, exclusively formed by carcinoma cells, and derived from fresh CRC tissue after mechanical dissociation. The ability to form colospheres was correlated with tumour aggressiveness. Their three-dimensional conformation prompted us to further investigate their potential interest as a preclinical cancer tool. METHODS: Patient-derived CRC xenografts were used to produce numerous colospheres. Mechanism of formation was elucidated by confocal microscopy. Expression analysis of a panel of 64 selected cancer-related genes by real-time qRT-PCR and hierarchical clustering allowed comparison of colospheres with parent xenografts. In vitro and in vivo assays were performed for migration and chemosensitivity studies. RESULTS: Colospheres, formed by tissue remodelling and compaction, remained viable several weeks in floating conditions, escaping anoikis through their strong cell-cell interactions. Colospheres matched the gene expression profile of the parent xenograft tissue. Colosphere-forming cells migrated in collagen I matrix and metastasised when subrenally implanted in nude mice. Besides, the colosphere responses to 5-fluorouracil and irinotecan, two standard drugs in CRC, reproduced those of the in vivo original xenografts. CONCLUSION: Colospheres closely mimic biological characteristics of in vivo CRC tumours. Consequently, they would be relevant ex vivo CRC models.

Newly characterised ex vivo colospheres as a three-dimensional colon cancer cell model of tumour aggressiveness.

BACKGROUND: New models continue to be required to improve our understanding of colorectal cancer progression. To this aim, we characterised in this study a three-dimensional multicellular tumour model that we named colospheres, directly obtained from mechanically dissociated colonic primary tumours and correlated with metastatic potential. METHODS: Colorectal primary tumours (n=203) and 120 paired non-tumoral colon mucosa were mechanically disaggregated into small fragments for short-term cultures. Features of tumours producing colospheres were analysed. Further characterisation was performed using colospheres, generated from a human colon cancer xenograft, and spheroids, formed on agarose by the paired cancer cell lines. RESULTS: Colospheres, exclusively formed by viable cancer cells, were obtained in only 1 day from 98 tumours (47%). Inversely, non-tumoral colonic mucosa never generated colospheres. Colosphere-forming capacity was statistically significantly associated with tumour aggressiveness, according to AJCC stage analysis. Despite a close morphology, colospheres displayed higher invasivity than did spheroids. Spheroids and colospheres migrated into Matrigel but matrix metalloproteinase (MMP)-2 and MMP-9 activity was detected only in colospheres. Mouse subrenal capsule assay revealed the unique tumorigenic and metastatic phenotype of colospheres. Moreover, colospheres and parental xenograft reproduced similar CD44 and CD133 expressions in which CD44+ cells represented a minority subset of the CD133+ population. CONCLUSION: The present colospheres provide an ex vivo three-dimensional model, potentially useful for studying metastatic process.

Specific detection of type II human chorionic gonadotropin beta subunit produced by trophoblastic and neoplastic cells.

BACKGROUND: The sequence of the beta-subunit of human chorionic gonadotropin (hCGß) varies depending on whether hCGß is encoded by type I or type II genes. Type II genes are upregulated in trophoblast and cancer but hCGß can be detected in the serum of nonpregnant women and healthy individuals. We aimed to determine whether monoclonal antibody (mAb) FBT11-II specifically detects hCGß encoded by type II genes (type II hCGß). METHODS: Competitive inhibition assays with synthetic peptides, immunocytochemical and immunohistochemical studies, type II hCGß dosing immunoassays and sequencing of CGB genes were performed. RESULTS: Competitive inhibition assays determined that mAb FBT11-II recognizes the type II hCGß derived peptide. CGB mRNA sequencing of JEG-3 (trophoblastic) and T24 (bladder) cell lines confirmed that JEG-3 expresses type II genes while T24 expresses exclusively type I. FBT11-II only recognizes JEG-expressed hCGß. Placenta immunohistochemical studies confirmed that type II hCGß expression is restricted to the syncytiotrophoblast. Immunoassays detected type II hCGß in serum of patients with either nontrophoblastic cancers or fetal Down syndrome. CONCLUSION: Type II gene expression can be detected using FBT11-II. This specific recognition could improve the clinical usefulness of assays aimed at either managing aggressive tumors or screening for Down syndrome.

Gene expression profiles of bladder cancers: evidence for a striking effect of in vitro cell models on gene patterns.

In order to assess the effect of in vitro models on the expression of key genes known to be implicated in the development or progression of cancer, we quantified by real-time quantitative PCR the expression of 28 key genes in three bladder cancer tissue specimens and in their derived cell lines, studied either as one-dimensional single cell suspensions, two-dimensional monolayers or three-dimensional spheroids. Global analysis of gene expression profiles showed that in vitro models had a dramatic impact upon gene expression. Remarkably, quantitative differences in gene expression of 2-63-fold were observed in 24 out of 28 genes among the cell models. In addition, we observed that the in vitro model which most closely mimicked in vivo mRNA phenotype varied with both the gene and the patient. These results provide evidence that mRNA expression databases based on cancer cell lines, which are studied to provide a rationale for selection of therapy on the basis of molecular characteristics of a patient's tumour, must be carefully interpreted.

MHC-dependent cytolysis of autologous tumor cells by lymphocytes infiltrating urothelial carcinomas.

Tumor-infiltrating lymphocytes (TIL) were grown from 23 urothelial carcinomas. Phenotyping analysis showed that the TIL cultures were mainly CD3+. Although CD4+ and CD8+ T-cell sub-sets were grown in culture, CD4+ T-cell sub-sets predominated over CD8+ T cells. Immunohistochemical studies performed on 5 tumor specimens confirmed this observation, and indicated that CD4+ T cells surrounded the tumor islets, whereas CD8+ T lymphocytes were localized among the tumor cells. Five short-term carcinoma cell lines established from these urothelial tumors were used as target cells in cytolysis assays in order to investigate the functional anti-tumor activity of autologous TIL. TIL from 4/5 tumors were lytic and 3 TIL lines displayed MHC-class-I-dependent cytotoxicity directed against autologous tumor cells. CD4+ T-cell-depletion experiments performed on TIL line 07 confirmed that CD8+ MHC-class-I-dependent CTL were the predominant effectors. Finally, experiments performed on 6 allogeneic urothelial-cancer cell lines matched for HLA-class-I molecules showed that TIL07 exhibited selective lytic activity toward tumor 07. These data indicate that CD8+ MHC-class-I-dependent CTL present in urothelial carcinomas are functional and may participate in the anti-tumor immune response.