Iris Simon

The treatment of choice for prostate cancer is androgen deprivation (ADT) and novel hormonal agents such as Abiraterone, Enzalutamide, or Apalutamide. Initially, this therapy is highly effective, but a significant challenge arises as most patients eventually develop resistance, resulting in castration-resistant prostate cancer (CRPC). Furthermore, the sequential use of these drugs can lead to cross-resistance, diminishing their efficacy. Tumor heterogeneity plays a pivotal role in the development of resistance to different treatments. This study utilized cellular models of CRPC to assess the response to Apalutamide when it was administered as a second- or third-line treatment. Functional and genetic analyses were conducted in various CRPC cell models exposed to Apalutamide. These analyses included real-time cell monitoring assays, flow cytometry, clonogenicity assays, and RT-qPCR. CRPC cell models were capable of continued proliferation, maintained cell cycle profiles similar to those of untreated cells, and retained their clonogenic potential. Cross-resistance to Apalutamide in models of ADT, ADT plus Enzalutamide, or Abiraterone resistance did not correlate with the expression levels of AR-V7 and AR-V9 variants. Gene expression analysis of resistant prostate cancer cell lines revealed that treatment with Apalutamide induced the emergence of more aggressive phenotypes, including cancer stem cells or neuroendocrine differentiation profiles. Most CRPC cell models developed cross-resistance to Apalutamide and were able to proliferate and retain their clonogenic capability. Apalutamide resistance was not linked to the expression of AR-V7 or AR-V9 variants but was instead associated to bypass of AR signaling pathway and the emergence of more aggressive expression profiles.

Pediatric acute myeloid leukemia (AML) is a rare and heterogeneous disease that remains the major cause of mortality in children with leukemia. To improve the outcome of pediatric AML we need to gain knowledge on the biological bases of this disease. NUP98-KDM5A (NK5A) fusion protein is present in a particular subgroup of young pediatric patients with poor outcome. We report the generation and characterization of human Embryonic Stem Cell (hESC) clonal lines with inducible expression of NK5A. Temporal control of NK5A expression during hematopoietic differentiation from hESC will be critical for elucidating its participation during the leukemogenic process.

Background: Platelets are active players in tumorigenesis, although the exact interactive mechanisms and their direct impact on tumor cells remain largely unknown.

BackgroundPlatelets are active players in tumorigenesis, although the exact interactive mechanisms and their direct impact on tumor cells remain largely unknown. MethodsBidirectional transference of lipids, proteins and RNA between platelets and tumor cells and its impact on tumor cell behavior and tumor process are analyzed in this work. Phenotypic, genetic and functional modifications induced by platelets were analyzed both in tumor cell lines and in circulating tumor cells (CTCs). ResultsBesides cross-talk between platelets and tumor cells, we demonstrated an efficient exchange of lipids, proteins and RNA. Remarkably, we observed that platelets transferred structural components to tumor cells with higher efficiency than tumor cells to platelets (p=0.001). This biological interplay occurred by direct contact, internalization or via extracellular vesicles. As a result, tumor cells acquired platelet markers (CD61 and CD42), showed decreased EpCAM, expressed epithelial-to-mesenchymal transition markers, and increased proliferation rates. Analysis of platelets marker CD61 in CTCs showed intra and inter patient heterogeneity.ConclusionsOur results demonstrated, for the first time, that platelets educate tumor cells by highly efficient transference of lipids, proteins and RNA through different mechanisms. These results suggest that tumor cells and CTCs might acquire highly dynamic and aggressive phenotypes due to platelets interaction including EMT, stem-like phenotype and high proliferative rates.

Androgen deprivation therapy (ADT) and novel hormonal agents (NHAs) (Abiraterone and Enzalutamide) are the goal standard for metastatic prostate cancer (PCa) treatment. Although ADT is initially effective, a subsequent castration resistance status (CRPC) is commonly developed. The expression of androgen receptor (AR) alternative splicing isoforms (AR-V7 and AR-V9) has been associated to CRPC. However, resistance mechanisms to novel NHAs are not yet well understood. Androgen-dependent PCa cell lines were used to generate resistant models to ADT only or in combination with Abiraterone and/or Enzalutamide (concomitant models). Functional and genetic analyses were performed for each resistance model by real-time cell monitoring assays, flow cytometry and RT-qPCR. In androgen-dependent PCa cells, the administration of Abiraterone and/or Enzalutamide as first-line treatment involved a critical inhibition of AR activity associated with a significant cell growth inhibition. Genetic analyses on ADT-resistant PCa cell lines showed that the CRPC phenotype was accompanied by overexpression of AR full-length and AR target genes, but not necessarily AR-V7 and/or AR-V9 isoforms. These ADT resistant cell lines showed higher proliferation rates, migration and invasion abilities. Importantly, ADT resistance induced cross-resistance to Abiraterone and/or Enzalutamide. Similarly, concomitant models possessed an elevated expression of AR full-length and proliferation rates and acquired cross-resistance to its alternative NHA as second-line treatment.

The transforming growth factor β (TGF-β) pathway acts as a double-edged sword in tumorigenesis. By constraining epithelial cell growth, TGF-β is a potent tumor suppressor. However, TGF-β also acts as a key player in the induction of epithelial-to-mesenchymal transition (EMT), thereby enhancing invasiveness and metastasis. Furthermore, TGF-β signaling has recently been correlated with resistance against both targeted and conventional anticancer agents. Here, we present data demonstrating a role for TGF-β in chemotherapy resistance in colorectal cancer (CRC). We discuss these results in the context of recent findings indicating TGF-β signaling as an emerging player in cancer drug resistance.

466 Background: Microsatellite Instability (MSI-H) occurs in 10-20% of colon tumors and has been attributed predominantly to gene silencing of DNA mismatch repairs (MMR) genes by mutation or methylation, including MSH2, PMS2 and in particular MLH1. Methods: MSI status for 276 primary stage II and III colorectal tumors have been determined (n=29 MSI-H, n=247 MSS and MSI-L) by immunohistochemically staining of MLH1 and PMS2 (for 90 patients) or by PRC amplification of six microsatellite DNA regions from paired normal and tumor tissues (for 186 patients). Full genome gene expression data for the same 276 tumors was available and used to identify genes that correlate with MSI-H status. All samples had full clinical information including 5-year follow-up and ColoPrint results (as described in Salazar et al. JCO 2011). Results: Most MSI-H patients were classified as ColoPrint low risk (26 of 29 patients; 90%) however this is only as subgroup of the 195 patients identified by ColoPrint as low risk. While ColoPrint had great prognostic power in this dataset (HR 2.37, p=0.0006), it does not identify MSI-H patients with high specificity. We therefore developed a MSI-gene signature of 64 genes using a 10-fold cross validation procedure to complement ColoPrint. The MSI-signature identifies MSI-H patients with high sensitivity (93.1% (27/29)) and high specificity (87.9% (217/247)) and an overall accuracy of 88.4% (244/276). The MSI-signature has prognostic power in the subset of stage II patients (n=215) with HR = 2.38 (95% CI 1.15-4.93, p=0.06. However, in multivariate analysis of MSI status and all clinical factors, ColoPrint was the only significant prognostic factor (HR 3.2; p=0.0014). The MSI-signature is currently validated in an independent patients set of 132 stage II patients (31 MSI-H, 101 MSS). Conclusions: The diagnostic MSI signature identifies patients with MSI-H status with high accuracy. In combination with the prognostic power of ColoPrint, the identification of MSI-H patients might add additional information for treatment of stage II patients.