The trophectoderm acts as a niche for the inner cell mass through C/EBPα-regulated IL-6 signaling

Gene regulation; Somatic cell reprogramming; TrophectodermRegulación de genes; Reprogramación de células somáticas; TrofoectodermoRegulació de gens; Reprogramació de cèl·lules somàtiques; TrofectodermaIL-6 has been shown to be required for somatic cell reprogramming into induced pluripotent stem cells (iPSCs). However, how Il6 expression is regulated and whether it plays a role during embryo development remains unknown. Here, we describe that IL-6 is necessary for C/EBPα-enhanced reprogramming of B cells into iPSCs but not for B cell to macrophage transdifferentiation. C/EBPα overexpression activates both Il6 and Il6ra genes in B cells and in PSCs. In embryo development, Cebpa is enriched in the trophectoderm of blastocysts together with Il6, while Il6ra is mostly expressed in the inner cell mass (ICM). In addition, Il6 expression in blastocysts requires Cebpa. Blastocysts secrete IL-6 and neutralization of the cytokine delays the morula to blastocyst transition. The observed requirement of C/EBPα-regulated IL-6 signaling for pluripotency during somatic cell reprogramming thus recapitulates a physiologic mechanism in which the trophectoderm acts as niche for the ICM through the secretion of IL-6.We thank C. Berenguer for help with B cell reprogramming and bone marrow collection; S. Nakagawa and B. Pernaute for advice on pre-implantation embryo culture and manipulation, and Kyle M. Loh for his valuable discussions; the flow cytometry and microscopy units of UPF-CRG for technical assistance; the CRG genomics core facility for sequencing and Graf laboratory members for critical discussions. Work in the laboratory of T.G. was supported by the Spanish Ministry of Economy, Industry and Competitiveness (Plan Estatal PID2019-109354GB-I00), the CRG, AGAUR (SGR 726), and a European Research Council Synergy grant (4D-Genome). M.P.-C. was supported by an FPI fellowship (BES-2016-076900). Work in the laboratory of M.S. was funded by the IRB and by grants from the Spanish Ministry of Economy co-funded by the European Regional Development Fund (SAF2017-82613-R), ERC (ERC-2014-AdG/669622), la Caixa Foundation, and Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement of Catalonia (Grup de Recerca consolidat 2017 SGR 282)

Human Metastatic Cholangiocarcinoma Patient-Derived Xenografts and Tumoroids for Preclinical Drug Evaluation

Human metastatic cholangiocarcinoma; Xenografts; TumoroidsColangiocarcinoma metastàtic humà; Xenoempelts; TumoroidesColangiocarcinoma metastásico humano; Xenoinjertos; TumoroidesPurpose: Cholangiocarcinoma (CCA) is usually diagnosed at advanced stages, with limited therapeutic options. Preclinical models focused on unresectable metastatic CCA are necessary to develop rational treatments. Pathogenic mutations in IDH1/2, ARID1A/B, BAP1, and BRCA1/2 have been identified in 30%–50% of patients with CCA. Several types of tumor cells harboring these mutations exhibit homologous recombination deficiency (HRD) phenotype with enhanced sensitivity to PARP inhibitors (PARPi). However, PARPi treatment has not yet been tested for effectiveness in patient-derived models of advanced CCA. Experimental Design: We have established a collection of patient-derived xenografts from patients with unresectable metastatic CCA (CCA_PDX). The CCA_PDXs were characterized at both histopathologic and genomic levels. We optimized a protocol to generate CCA tumoroids from CCA_PDXs. We tested the effects of PARPis in both CCA tumoroids and CCA_PDXs. Finally, we used the RAD51 assay to evaluate the HRD status of CCA tissues. Results: This collection of CCA_PDXs recapitulates the histopathologic and molecular features of their original tumors. PARPi treatments inhibited the growth of CCA tumoroids and CCA_PDXs with pathogenic mutations of BRCA2, but not those with mutations of IDH1, ARID1A, or BAP1. In line with these findings, only CCA_PDX and CCA patient biopsy samples with mutations of BRCA2 showed RAD51 scores compatible with HRD. Conclusions: Our results suggest that patients with advanced CCA with pathogenic mutations of BRCA2, but not those with mutations of IDH1, ARID1A, or BAP1, are likely to benefit from PARPi therapy. This collection of CCA_PDXs provides new opportunities for evaluating drug response and prioritizing clinical trials.This work was supported by grants from the Fundació Marató TV3 awarded to T. Macarulla, M. Melé, and S. Peiró; BeiGene research grant awarded to T. Macarulla and S. Peiró; AECC (INVES20036TIAN), Ramón y Cajal investigator program (RYC2020-029098-I), Proyecto de I+D+i (PID2019-108008RJ-I00), and FERO Foundation grant awarded to T.V. Tian; Proyecto de Investigación en Salud from the Instituto de Salud Carlos III (ISCIII) (PI20/00898) awarded to T. Macarulla; FIS/FEDER from the Instituto de Salud Carlos III (ISCIII) (PI12/01250; CP08/00223; PI16/00253 and CB16/12/00449) awarded to S. Peiró; and Ramón y Cajal investigator program (RYC-2017-22249) awarded to M. Melé. Q. Serra-Camprubí is a recipient of the Ph.D. fellowship from La Caixa Foundation (LCF/PR/PR12/51070001). A. Llop-Guevara was supported by the AECC (INVES20095LLOP) and V. Serra by the ISCIII (CPII19/00033). E.J. Arenas was funded by the AECC (POSTD211413AREN). J. Arribas is funded by the Instituto de Salud Carlos III (AC15/00062, CB16/12/00449, and PI22/00001). This publication is based upon the work of COST Action CA18122, European Cholangiocarcinoma Network, supported by the COST (European Cooperation in Science and Technology, www.cost.eu), a funding agency for research and innovation networks. The authors would like to thank Dr. V.A. Raker for manuscript editing and Drs. N. Herranz and J. Mateo for scientific discussions. The authors acknowledge the infrastructure and support of the FERO Foundation, La Caixa Foundation, and the Cellex Foundation

Near-tetraploid cancer cells show chromosome instability triggered by replication stress and exhibit enhanced invasiveness.

A considerable proportion of tumors exhibit aneuploid karyotypes, likely resulting from the progressive loss of chromosomes after whole-genome duplication. Here, by using isogenic diploid and near-tetraploid (4N) single-cell-derived clones from the same parental cell lines, we aimed at exploring how polyploidization affects cellular functions and how tetraploidy generates chromosome instability. Gene expression profiling in 4N clones revealed a significant enrichment of transcripts involved in cell cycle and DNA replication. Increased levels of replication stress in 4N cells resulted in DNA damage, impaired proliferation caused by a cell cycle delay during S phase, and higher sensitivity to S phase checkpoint inhibitors. In fact, increased levels of replication stress were also observed in nontransformed, proliferative posttetraploid RPE1 cells. Additionally, replication stress promoted higher levels of intercellular genomic heterogeneity and ongoing genomic instability, which could be explained by high rates of mitotic defects, and was alleviated by the supplementation of exogenous nucleosides. Finally, our data found that 4N cancer cells displayed increased migratory and invasive capacity, both in vitro and in primary colorectal tumors, indicating that tetraploidy can promote aggressive cancer cell behavior.-Wangsa, D., Quintanilla, I., Torabi, K., Vila-Casadesus, M., Ercilla, A., Klus, G., Yuce, Z., Galofre, C., Cuatrecasas, M., Lozano, J. J., Agell, N., Cimini, D., Castells, A., Ried, T., Camps, J. Near-tetraploid cancer cells show chromosome instability triggered by replication stress and exhibit enhanced invasiveness

Carm1-arginine methylation of the transcription factor C/EBPα regulates transdifferentiation velocity

Here, we describe how the speed of C/EBPα-induced B cell to macrophage transdifferentiation (BMT) can be regulated, using both mouse and human models. The identification of a mutant of C/EBPα (C/EBPαR35A) that greatly accelerates BMT helped to illuminate the mechanism. Thus, incoming C/EBPα binds to PU.1, an obligate partner expressed in B cells, leading to the release of PU.1 from B cell enhancers, chromatin closing and silencing of the B cell program. Released PU.1 redistributes to macrophage enhancers newly occupied by C/EBPα, causing chromatin opening and activation of macrophage genes. All these steps are accelerated by C/EBPαR35A, initiated by its increased affinity for PU.1. Wild-type C/EBPα is methylated by Carm1 at arginine 35 and the enzyme’s perturbations modulate BMT velocity as predicted from the observations with the mutant. Increasing the proportion of unmethylated C/EBPα in granulocyte/macrophage progenitors by inhibiting Carm1 biases the cell’s differentiation toward macrophages, suggesting that cell fate decision velocity and lineage directionality are closely linked processes