Cellular Proliferation in the Prognosis of Intermediate Grade Mast Cell Tumour in Dogs

This was a retrospective study including ninety samples of dogs with a histological diagnosis of intermediate grade cutaneous mast cell tumour (MCT). The objectives of the study were to validate Minichromosome Maintenance Protein 7 (MCM7) as a prognostic marker in MCTs and to compare the ability of mitotic index (MI), Ki67 and MCM7 to predict outcome. The median survival for the entire population was not reached at 2099 days. The mean survival time was 1708 days. Seventy-two cases were censored after a median follow up of 1136 days and eighteen dogs died for causes related to the MCT after a median of 116 days. For each sample MI, Ki67 and MCM7 were determined. The Receiver Operating Characteristic (ROC) curve was obtained for each prognostic marker to evaluate the performance of the test, expressed as area under the curve, and whether the published threshold value was adequate. Kaplan-Meier and corresponding logrank test for MI, Ki67 and MCM7 as binary variables was highly significant (P<0.0001). Multivariable regression analysis of MI, Ki67 and MCM7 corrected for age and surgical margins indicated that the higher risk of dying of MCT was associated with MCM7 > 0.18 (Hazard Ration [HR] 14.7; P<0.001) followed by MI > 5 (HR 13.9; P<0.001) and Ki67 > 0.018 (HR 8.9; P<0.001). Concluding, the present study confirmed that MCM7 is an excellent prognostic marker in cutaneous MCTs being able to divide Patnaik intermediate grade tumours in two categories with different prognosis. Ki67 was equally good confirming its value as a prognostic marker in intermediate grade MCTs. The mitotic index was extremely specific, but lacked of sensitivity. Interestingly, mitotic index, Ki67 and MCM7 were independent from each other suggesting that their combination would improve their individual prognostic value.

Dissecting the role of IGF2BP3 in the stress-adaptive response and in intercellular communication in Ewing Sarcoma.

Tumor microenvironment has emerged as key factor influencing tumor progression and metastatization. In this context, small vesicles produced by cancer cells can influence the fate of their surroundings via the horizontal transfer of specific molecular cargos. Ewing Sarcoma, the second most common bone tumor in young patients, presents early metastasis associated to worse prognosis. The RNA binding protein Insulin-like Growth Factor 2 mRNA Binding Protein 3 (IGF2BP3) exerts a pro-oncogenic role associated with metastasis formation and worse prognosis in Ewing Sarcoma. Our aim was to investigate the still unexplored role of IGF2BP3 in the stress-adaptive response to tumor microenvironment and in the interactions between Ewing Sarcoma cells. Hypoxia is a major feature of Ewing Sarcoma microenvironment and we demonstrated that IGF2BP3 can direct the CXCR4-mediated migratory response to CXCL12 in Ewing Sarcoma cells subjected to oxygen deprivation. We also discovered that the interaction between IGF2BP3 and CXCR4 is regulated through CD164 and which colocalize at plasma membrane level, upon CXCL12 exposure. Interestingly, high IGF2BP3 levels in Ewing Sarcoma metastatic lesions positively correlated with the expression of both CD164 and CXCR4, indicating the IGF2BP3/CD164/CXCR4 oncogenic axis as a critical modulator of Ewing Sarcoma metastatic progression. We demonstrated for the first time that IGF2BP3 is loaded into Ewing Sarcoma derived exosomes, accordingly to its cellular levels. We discovered that IGF2BP3+ exosomes carry high levels of IGF2BP3-client mRNAs involved in cellular migration, CD164 and IGF1R, and, by transferring this cargo, sustain the migratory abilities of receiving cells, induce a sharp up-regulation of CD164, CXCR4 and IGF1R and enhance the activation of AKT/mTOR and ERK down-stream signalling pathways. We demostrated that the pro-tumorigenic role of IGF2BP3 is not only exerted at cellular level, but that intercellular communication is crucial in the context of Ewing Sarcoma microenvironment.