Targeting CD44 and other pleiotropic co-receptors as a means for broad inhibition of tumor growth and metastasis.

Although progress has been made in the treatment of cancer, particularly for the four major types of cancers affecting the lungs, colon, breast and prostate, resistance to cancer treatment often emerges upon inhibition of major signaling pathways, which leads to the activation of additional pathways as a last-resort survival mechanism by the cancer cells. This signaling plasticity provides cancer cells with a level of operational freedom, reducing treatment efficacy. Plasticity is a characteristic of cancer cells that are not only able to switch signaling pathways but also from one cellular state (differentiated cells to stem cells or vice versa) to another. It seems implausible that the inhibition of one or a few signaling pathways of heterogeneous and plastic tumors can sustain a durable effect. We propose that inhibiting molecules with pleiotropic functions such as cell surface co-receptors can be a key to preventing therapy escape instead of targeting bona fide receptors. Therefore, we ask the question whether co-receptors often considered as "accessory molecules" are an overlooked key to control cancer cell behavior.

Complications after Heller myotomy in children: a national multicenter study on the impact of prior endoscopic dilatation and identification of risk factors.

BACKGROUND: Although esophageal achalasia has been historically treated by Heller myotomy, endoscopic esophageal dilatations are nowadays often the first-line treatment in children. The aim was to assess whether performing an endoscopic dilatation before a Heller myotomy is associated with higher risks of esophageal perforation in children. METHODS: A retrospective multicentric study was performed, including children that underwent a Heller myotomy (2000-2022, 10 centers). Two groups were compared based on the history of previous dilatation before myotomy. Outcomes esophageal perforation (intra-operative or secondary) and post-operative complications requiring surgery (Clavien-Dindo III). Statistics Comparisons using contingency tables or Kruskal-Wallis when appropriate. Statistical significance: p-value < 0.05. RESULTS: A Heller myotomy was performed in 77 children (median age: 11.8 years), with prior endoscopic dilatation in 53% (n = 41). A laparoscopic approach was used in 90%, with associated fundoplication in 95%. Esophageal perforation occurred in 19% of children (n = 15), including 12 patients with intra-operative mucosal tear and 3 with post-operative complications related to an unnoticed esophageal perforation. Previous endoscopic dilatation did not increase the risk of esophageal perforation (22% vs 17%, OR: 1.4, 95%CI: 0.43-4.69). Post-operative complications occurred in 8% (n = 6), with similar rates regardless of prior endoscopic dilatation. Intra-operative mucosal tear was the only risk factor for post-operative complications, increasing the risk of complications from 5 to 25% (OR: 6.89, 95%CI: 1.38-31.87). CONCLUSIONS: Prior endoscopic dilatations did not increase the risk of esophageal perforation or postoperative complications of Heller myotomy in this cohort of children with achalasia. Mucosal tear was identified as a risk factor for post-operative complications.

Quantitative live imaging reveals a direct interaction between CD44v6 and MET in membrane domains upon activation with both MET ligands, HGF and internalin B.

Deregulation of the receptor tyrosine kinase MET/hepatocyte growth factor (HGF) pathway results in several pathological processes involved in tumor progression and metastasis. In a different context, MET can serve as an entry point for the bacterium Listeria monocytogenes, when activated by the internalin B (InlB) protein during infection of non-phagocytic cells. We have previously demonstrated that MET requires CD44v6 for its ligand-induced activation. However, the stoichiometry and the steps required for the formation of this complex, are still unknown. In this work, we studied the dynamics of the ligand-induced interaction of CD44v6 with MET at the plasma membrane. Using Förster resonance energy transfer-based fluorescence lifetime imaging microscopy in T-47D cells, we evidenced a direct interaction between MET and CD44v6 promoted by HGF and InlB in live cells. In the absence of MET, fluorescence correlation spectroscopy experiments further showed the dimerization of CD44v6 and the increase of its diffusion induced by HGF and InlB. In the presence of MET, stimulation of the cells by HGF or InlB significantly decreased the diffusion of CD44v6, in line with the formation of a ternary complex of MET with CD44v6 and HGF/InlB. Finally, similarly to HGF/InlB, disruption of liquid-ordered domains (Lo) by methyl-ß-cyclodextrin increased CD44v6 mobility suggesting that these factors induce the exit of CD44v6 from the Lo domains. Our data led us to propose a model for MET activation, where CD44v6 dimerizes and diffuses rapidly out of Lo domains to form an oligomeric MET/ligand/CD44v6 complex that is instrumental for MET activation.

Identification of an Imidazopyridine-based Compound as an Oral Selective Estrogen Receptor Degrader for Breast Cancer Therapy.

The pro-oncogenic activities of estrogen receptor alpha (ERα) drive breast cancer pathogenesis. Endocrine therapies that impair the production of estrogen or the action of the ERα are therefore used to prevent primary disease metastasis. Although recent successes with ERα degraders have been reported, there is still the need to develop further ERα antagonists with additional properties for breast cancer therapy. We have previously described a benzothiazole compound A4B17 that inhibits the proliferation of androgen receptor-positive prostate cancer cells by disrupting the interaction of the cochaperone BAG1 with the AR. A4B17 was also found to inhibit the proliferation of estrogen receptor-positive (ER+) breast cancer cells. Using a scaffold hopping approach, we report here a group of small molecules with imidazopyridine scaffolds that are more potent and efficacious than A4B17. The prototype molecule X15695 efficiently degraded ERα and attenuated estrogen-mediated target gene expression as well as transactivation by the AR. X15695 also disrupted key cellular protein-protein interactions such as BAG1-mortalin (GRP75) interaction as well as wild-type p53-mortalin or mutant p53-BAG2 interactions. These activities together reactivated p53 and resulted in cell-cycle block and the induction of apoptosis. When administered orally to in vivo tumor xenograft models, X15695 potently inhibited the growth of breast tumor cells but less efficiently the growth of prostate tumor cells. We therefore identify X15695 as an oral selective ER degrader and propose further development of this compound for therapy of ER+ breast cancers. Significance: An imidazopyridine that selectively degrades ERα and is orally bioavailable has been identified for the development of ER+ breast cancer therapeutics. This compound also activates wild-type p53 and disrupts the gain-of-function tumorigenic activity of mutant p53, resulting in cell-cycle arrest and the induction of apoptosis.

Automated high-throughput image processing as part of the screening platform for personalized oncology.

Cancer is a devastating disease and the second leading cause of death worldwide. However, the development of resistance to current therapies is making cancer treatment more difficult. Combining the multi-omics data of individual tumors with information on their in-vitro Drug Sensitivity and Resistance Test (DSRT) can help to determine the appropriate therapy for each patient. Miniaturized high-throughput technologies, such as the droplet microarray, enable personalized oncology. We are developing a platform that incorporates DSRT profiling workflows from minute amounts of cellular material and reagents. Experimental results often rely on image-based readout techniques, where images are often constructed in grid-like structures with heterogeneous image processing targets. However, manual image analysis is time-consuming, not reproducible, and impossible for high-throughput experiments due to the amount of data generated. Therefore, automated image processing solutions are an essential component of a screening platform for personalized oncology. We present our comprehensive concept that considers assisted image annotation, algorithms for image processing of grid-like high-throughput experiments, and enhanced learning processes. In addition, the concept includes the deployment of processing pipelines. Details of the computation and implementation are presented. In particular, we outline solutions for linking automated image processing for personalized oncology with high-performance computing. Finally, we demonstrate the advantages of our proposal, using image data from heterogeneous practical experiments and challenges.

Outcome of long gap esophageal atresia at 6 years: A prospective case control cohort study.

BACKGROUND DATA: EA is the most frequent congenital esophageal malformation. Long gap EA remains a therapeutic challenge for pediatric surgeons. A case case-control prospective study from a multi-institutional national French data base was performed to assess the outcome, at age of 1 and 6 years, of long gap esophageal atresia (EA) compared with non-long gap EA/tracheo-esophageal fistula (TEF). The secondary aim was to assess whether initial treatment (delayed primary anastomosis of native esophagus vs. esophageal replacement) influenced mortality and morbidity at ages 1 and 6 years. METHODS: A multicentric population-based prospective study was performed and included all patients who underwent EA surgery in France from January 1, 2008 to December 31, 2010. A comparative study was performed with non-long gap EA/TEF patients. Morbidity at birth, 1 year, and 6 years was assessed. RESULTS: Thirty-one patients with long gap EA were compared with 62 non-long gap EA/TEF patients. At age 1 year, the long gap EA group had longer parenteral nutrition support and longer hospital stay and were significantly more likely to have complications both early post-operatively and before age 1 year compared with the non-long gap EA/TEF group. At 6 years, digestive complications were more frequent in long gap compared to non-long gap EA/TEF patients. Tracheomalacia was the only respiratory complication that differed between the groups. Spine deformation was less frequent in the long gap group. There were no differences between conservative and replacement groups at ages 1 and 6 years except feeding difficulties that were more common in the native esophagus group. CONCLUSIONS: Long gap strongly influenced digestive morbidity at age 6 years.

Peri- and neonatal factors influencing mortality and morbidity 2 years after esophageal atresia primary repair: a single center retrospective study.

Long-term digestive, respiratory, and neurological morbidity is significant in children who have undergone surgery for esophageal atresia (EA), especially after staged repair for long-gap EA. Risk factors for morbidity after primary repair (non-long-gap populations) have been less documented. We investigated peri- and neonatal factors associated with unfavorable outcomes in children 2 years after primary esophageal anastomosis. This was a single-center retrospective study, based on neonatal, surgical, and pediatric records of children born between December 1, 2002, and December 31, 2018, and followed up to age 2 years. The primary endpoint was unfavorable outcome at 2 years of age, defined by death or survival with severe respiratory, digestive, or neurologic morbidity. Univariate analyses followed by logistic regression analyses were performed to identify the peri- and neonatal risk factors of unfavorable outcomes among survivors at discharge. A total of 150 neonates were included (mean birth weight 2520 ± 718 g, associated malformations 61%); at age 2, 45 (30%) had one or more severe morbidities and 11 had died during the neonatal stay and 2 after discharge (8.7% deaths). In multivariate analyses of the 139 survivors at discharge, duration of ventilatory support (invasive and non-invasive) for more than 8 days (OR 3.74; CI95% [1.68-8.60]; p = 0.001) and achievement of full oral feeding before hospital discharge (OR 0.20; CI95% [0.06-0.56]; p = 0.003) were independently associated with adverse outcome after adjustment for sex, preterm birth, associated heart defect, any surgical complication, and the occurrence of more than one nosocomial infections during the neonatal stay. CONCLUSIONS: Post-operative ventilation and feeding management strategies may represent an opportunity for quality-of-care improvement to positively impact long-term outcomes after primary esophageal atresia repair. WHAT IS KNOWN: • Children operated on for esophageal atresia experience long-term digestive, respiratory, and neurologic morbidity, especially after multiple-stage esophageal repair. • Exclusive oral feeding at discharge is associated with a decreased risk of medical complications in the first years of life, in studies including all types of esophageal atresia repair. Outcomes of children after primary repair (non-long gap populations) have been less documented. WHAT IS NEW: • In our retrospective cohort of children with one-stage esophageal atresia repair, ventilatory support for more than 8 days and inability to achieve full oral feeding before hospital discharge in the neonatal period were independently associated with adverse digestive, respiratory, and neurologic outcomes at 2 years in survivors. • Both these factors are potentially modifiable, representing an opportunity for quality-of-care improvement to positively impact long-term outcomes. These results might also help identify children at risk of unfavorable evolution, to customize a multi-disciplinary follow-up program.

Challenges in glioblastoma research: focus on the tumor microenvironment.

Glioblastoma (GBM) is the most deadly type of malignant brain tumor, despite extensive molecular analyses of GBM cells. In recent years, the tumor microenvironment (TME) has been recognized as an important player and therapeutic target in GBM. However, there is a need for a full and integrated understanding of the different cellular and molecular components involved in the GBM TME and their interactions for the development of more efficient therapies. In this review, we provide a comprehensive report of the GBM TME, which assembles the contributions of physicians and translational researchers working on brain tumor pathology and therapy in France. We propose a holistic view of the subject by delineating the specific features of the GBM TME at the cellular, molecular, and therapeutic levels.

Retrospective evaluation of clinical and molecular data of 148 cases of esophageal atresia.

Developmental abnormalities provide a unique opportunity to seek for the molecular mechanisms underlying human organogenesis. Esophageal development remains incompletely understood and elucidating causes for esophageal atresia (EA) in humans would contribute to achieve a better comprehension. Prenatal detection, syndromic classification, molecular diagnosis, and prognostic factors in EA are challenging. Some syndromes have been described to frequently include EA, such as CHARGE, EFTUD2-mandibulofacial dysostosis, Feingold syndrome, trisomy 18, and Fanconi anemia. However, no molecular diagnosis is made in most cases, including frequent associations, such as Vertebral-Anal-Cardiac-Tracheo-Esophageal-Renal-Limb defects (VACTERL). This study evaluates the clinical and genetic test results of 139 neonates and 9 fetuses followed-up at the Necker-Enfants Malades Hospital over a 10-years period. Overall, 52 cases were isolated EA (35%), and 96 were associated with other anomalies (65%). The latter group is divided into three subgroups: EA with a known genomic cause (9/148, 6%); EA with Vertebral-Anal-Cardiac-Tracheo-Esophageal-Renal-Limb defects (VACTERL) or VACTERL/Oculo-Auriculo-Vertebral Dysplasia (VACTERL/OAV) (22/148, 14%); EA with associated malformations including congenital heart defects, duodenal atresia, and diaphragmatic hernia without known associations or syndromes yet described (65/148, 44%). Altogether, the molecular diagnostic rate remains very low and may underlie frequent non-Mendelian genetic models.

Alternative splicing downstream of EMT enhances phenotypic plasticity and malignant behavior in colon cancer.

Phenotypic plasticity allows carcinoma cells to transiently acquire the quasi-mesenchymal features necessary to detach from the primary mass and proceed along the invasion-metastasis cascade. A broad spectrum of epigenetic mechanisms is likely to cause the epithelial-to-mesenchymal (EMT) and mesenchymal-to-epithelial (MET) transitions necessary to allow local dissemination and distant metastasis. Here, we report on the role played by alternative splicing (AS) in eliciting phenotypic plasticity in epithelial malignancies with focus on colon cancer. By taking advantage of the coexistence of subpopulations of fully epithelial (EpCAMhi) and quasi-mesenchymal and highly metastatic (EpCAMlo) cells in conventional human cancer cell lines, we here show that the differential expression of ESRP1 and other RNA-binding proteins (RBPs) downstream of the EMT master regulator ZEB1 alters the AS pattern of a broad spectrum of targets including CD44 and NUMB, thus resulting in the generation of specific isoforms functionally associated with increased invasion and metastasis. Additional functional and clinical validation studies indicate that both the newly identified RBPs and the CD44s and NUMB2/4 splicing isoforms promote local invasion and distant metastasis and are associated with poor survival in colon cancer. The systematic elucidation of the spectrum of EMT-related RBPs and AS targets in epithelial cancers, apart from the insights in the mechanisms underlying phenotypic plasticity, will lead to the identification of novel and tumor-specific therapeutic targets.

CD44 expressed by myeloid cells promotes glioma invasion.

Glioblastoma multiforme (GBM) is one of the most common and malignant brain tumors in adulthood with a median survival of only 15 months. This poor prognosis is related to GBM's ability to extensively infiltrate the surrounding brain parenchyma resulting in diffuse spread of neoplastic cells in the brain, responsible for high rate of recurrence. CD44 (Cluster of Differentiation 44) is a transmembrane protein, overexpressed in multiple cancer types, including gliomas, and implicated in cell motility, proliferation and angiogenesis. Multiple studies have investigated the role of CD44 in GBM cells and have highlighted a link between tumor malignancy and CD44 expression. However up to date, little is known of the role of CD44 on cells from the tumor microenvironment (TME). Here, we have investigated a potential role of CD44 in the TME in regards to GBM invasiveness. Using an ex-vivo organotypic brain slice invasion assay, we show that absence of CD44 from the TME impairs the ability of glioma cells to invade the surrounding brain parenchyma. By deleting CD44 in the astrocytic, endothelial and myeloid compartments, we show that it is specifically CD44 expression in myeloid cells that is responsible for the observed phenotype. Combining in vivo studies in cell-specific knock-out mice and in vitro analyses on primary microglia we demonstrate that myeloid CD44 is implicated in Toll Like Receptor 2 signaling and is a major regulator of Matrix metalloproteinase 9 expression.

Direct interaction of TrkA/CD44v3 is essential for NGF-promoted aggressiveness of breast cancer cells.

BACKGROUND: CD44 is a multifunctional membrane glycoprotein. Through its heparan sulfate chain, CD44 presents growth factors to their receptors. We have shown that CD44 and Tropomyosin kinase A (TrkA) form a complex following nerve growth factor (NGF) induction. Our study aimed to understand how CD44 and TrkA interact and the consequences of inhibiting this interaction regarding the pro-tumoral effect of NGF in breast cancer. METHODS: After determining which CD44 isoforms (variants) are involved in forming the TrkA/CD44 complex using proximity ligation assays, we investigated the molecular determinants of this interaction. By molecular modeling, we isolated the amino acids involved and confirmed their involvement using mutations. A CD44v3 mimetic peptide was then synthesized to block the TrkA/CD44v3 interaction. The effects of this peptide on the growth, migration and invasion of xenografted triple-negative breast cancer cells were assessed. Finally, we investigated the correlations between the expression of the TrkA/CD44v3 complex in tumors and histo-pronostic parameters. RESULTS: We demonstrated that isoform v3 (CD44v3), but not v6, binds to TrkA in response to NGF stimulation. The final 10 amino acids of exon v3 and the TrkA H112 residue are necessary for the association of CD44v3 with TrkA. Functionally, the CD44v3 mimetic peptide impairs not only NGF-induced RhoA activation, clonogenicity, and migration/invasion of breast cancer cells in vitro but also tumor growth and metastasis in a xenograft mouse model. We also detected TrkA/CD44v3 only in cancerous cells, not in normal adjacent tissues. CONCLUSION: Collectively, our results suggest that blocking the CD44v3/TrkA interaction can be a new therapeutic option for triple-negative breast cancers.

Santulli Procedure Revisited in Congenital Intestinal Malformations and Postnatal Intestinal Injuries: Preliminary Report of Experience.

In our experience, the Santulli procedure (SP) can improve bowel recovery in congenital intestinal malformations, necrotizing enterocolitis (NEC), and bowel perforation. All cases managed at our institution using SP between 2012 and 2017 were included in this study. Forty-one patients underwent SP (median age: 39 (0-335) days, median weight: 2987 (1400-8100) g) for intestinal atresia (51%, two gastroschisis), NEC (29%), midgut volvulus (10%), Hirschsprung's disease (5%), or bowel perforation (5%), with at least one intestinal suture below the Santulli in 10% of cases. The SP was performed as a primary procedure (57%) or as a double-ileostomy reversal. Anal-stool passing occurred within a median of 9 (2-36) days for 95% of patients, regardless of the diversion level or the underlying disease. All three patients requiring repeated surgery for Santulli dysfunction had presented with stoma prolapse (p < 0.01). Stoma closure was performed after a median of 45 (14-270) days allowing efficient transit after a median of 2 (1-6) days. After a median follow-up of 2.9 (0.7-7.2) years, two patients died (cardiopathy and brain hemorrhage), full oral intake had been achieved in 90% of patients, and all survivors had normal bowel movement. Whether used as primary or secondary surgery, the SP allows rapid recovery of intestinal motility and function.

Predicting Factors of Protracted Intestinal Failure in Children with Gastroschisis.

OBJECTIVE: To identify prenatal and neonatal predictors of short bowel syndrome-related intestinal failure (SBS-IF) in gastroschisis. STUDY DESIGN: This retrospective study included all patients with gastroschisis born between 2000 and 2017 who were enrolled in our home parenteral nutrition program, and all patients with gastroschisis born in our institution who survived 2 weeks, during the same time period. Prenatal ultrasound features, neonatal status, anatomic features, oral feeding, and parenteral nutrition dependency were analyzed. RESULTS: Among 180 patients, 35 required long-term parenteral nutrition (SBS-IF group) and 145 acquired full oral feeding within 6 months (oral feeding group). The mean follow-up was 7.9 years (IQR, 1.6-17.5 years) and 5.0 years (IQR, 0.1-18.2 years), respectively. Both bowel matting (OR, 14.23; 1.07-16.7; P = .039) and secondarily diagnosed atresia or stenosis (OR, 17.78; 3.13-100.98; P = .001) were independent postnatal predictors of SBS-IF. Eighteen children (51% of the SBS-IF group) were still dependent on artificial nutrition at the last follow-up. patients with SBS-IF who achieved full oral feeding had a median residual small-bowel length of 74 cm (IQR, 51-160 cm) vs 44 cm (IQR, 10-105 cm) for those still dependent on artificial nutrition (P = .02). An initial residual small bowel length of more than 50 cm was the best predictive cut-off for nutritional autonomy, with a sensitivity of 67% and a specificity of 100%. CONCLUSIONS: Bowel matting, complex gastroschisis, and secondary intestinal obstruction were associated with SBS-IF in gastroschisis. For patients with SBS-IF, a small bowel length of more than 50 cm was predictive of secondary nutritional autonomy.

PAK3 is a key signature gene of the glioma proneural subtype and affects its proliferation, differentiation and growth.

PURPOSE: Gliomas are the most lethal adult primary brain cancers. Recent advances in their molecular characterization have contributed to a better understanding of their pathophysiology, but there is still a need to identify key genes controling glioma cell proliferation and differentiation. The p21-activated kinases PAK1 and PAK2 play essential roles in cell division and brain development and are well-known oncogenes. In contrast, the role of PAK3 in cancer is poorly understood. It is known, however, that this gene is involved in brain ontogenesis and has been identified as a gene of the proneural subtype signature in glioblastomas. METHODS: To better understand the role of PAK kinases in the pathophysiology of gliomas, we conducted expression analyses by querying multiple gene expression databases and analyzing primary human glioma samples. We next studied PAK3 expression upon differentiation in patient-derived cell lines (PDCLs) and the effects of PAK3 inhibition by lentiviral-mediated shRNA on glioma cell proliferation, differentiation and tumor growth. RESULTS: We show that contrary to PAK1 and PAK2, high PAK3 expression positively correlates with a longer survival of glioma patients. We also found that PAK3 displays differential expression patterns between glioma sub-groups with a higher expression in 1p/19q-codeleted oligodendrogliomas, and is highly expressed in tumors and PDCLs of the proneural subtype. In PDCLs, high PAK3 expression negatively correlated with proliferation and positively correlated with neuronal differentiation. Inhibition of PAK3 expression increased PDCL proliferation and glioma tumor growth in nude mice. CONCLUSIONS: Our results indicate that PAK3 plays a unique role among PAKs in glioma development and may represent a potential therapeutic target.

Esophageal Atresia and Respiratory Morbidity.

BACKGROUND AND OBJECTIVES: Respiratory diseases are common in children with esophageal atresia (EA), leading to increased morbidity and mortality in the first year. The primary study objective was to identify the factors associated with readmissions for respiratory causes in the first year in EA children. METHODS: A population-based study. We included all children born between 2008 and 2016 with available data and analyzed factors at birth and 1 year follow-up. Factors with a P value <.10 in univariate analyses were retained in logistic regression models. RESULTS: Among 1460 patients born with EA, 97 (7%) were deceased before the age of 1 year, and follow-up data were available for 1287 patients, who constituted our study population. EAs were Ladd classification type III or IV in 89%, preterm birth was observed in 38%, and associated malformations were observed in 52%. Collectively, 61% were readmitted after initial discharge in the first year, 31% for a respiratory cause. Among these, respiratory infections occurred in 64%, and 35% received a respiratory treatment. In logistic regression models, factors associated with readmission for a respiratory cause were recurrence of tracheoesophageal fistula, aortopexy, antireflux surgery, and tube feeding; factors associated with respiratory treatment were male sex and laryngeal cleft. CONCLUSIONS: Respiratory morbidity in the first year after EA repair is frequent, accounting for >50% of readmissions. Identifying high risk groups of EA patients (ie, those with chronic aspiration, anomalies of the respiratory tract, and need for tube feeding) may guide follow-up strategies.

CD44 loss of function sensitizes AML cells to the BCL-2 inhibitor venetoclax by decreasing CXCL12-driven survival cues.

Acute myeloid leukemia (AML) has a poor prognosis under the current standard of care. In recent years, venetoclax, a BCL-2 inhibitor, was approved to treat patients who are ineligible for intensive induction chemotherapy. However, complete remission rates with venetoclax-based therapies are hampered by minimal residual disease (MRD) in a proportion of patients, leading to relapse. MRD is a result of leukemic stem cells being retained in bone marrow protective environments; activation of the CXCL12-CXCR4 pathway was shown to be relevant to this process. An important role is also played by cell adhesion molecules such as CD44, which has been shown to be crucial for the development of AML. Here we show that CD44 is involved in CXCL12 promotion of resistance to venetoclax-induced apoptosis in human AML cell lines and AML patient samples, which could be abrogated by CD44 knock down, knockout, or blocking with an anti-CD44 antibody. Split-Venus bimolecular fluorescence complementation showed that CD44 and CXCR4 physically associate at the cell membrane upon CXCL12 induction. In the venetoclax-resistant OCI-AML3 cell line, CXCL12 promoted an increase in the proportion of cells expressing high levels of embryonic stem cell core transcription factors (ESC-TFs: Sox2, Oct4, Nanog) abrogated by CD44 knockdown. This ESC-TF-expressing subpopulation which could be selected by venetoclax treatment, exhibited a basally enhanced resistance to apoptosis and expressed higher levels of CD44. Finally, we developed a novel AML xenograft model in zebrafish, which showed that CD44 knockout sensitizes OCI-AML3 cells to venetoclax treatment in vivo. Our study shows that CD44 is a potential molecular target for sensitizing AML cells to venetoclax-based therapies.

Plasticity in Colorectal Cancer: Why Cancer Cells Differentiate.

The cancer stem cell hypothesis poses that the bulk of differentiated cells are non-tumorigenic and only a subset of cells with self-renewal capabilities drive tumor initiation and progression. This means that differentiation could have a tumor-suppressive effect. Accumulating evidence shows, however, that in some solid tumors, like colorectal cancer, such a hierarchical organization is necessary. The identification of Lgr5 as a reliable marker of normal intestinal epithelial stem cells, together with strategies to trace cell lineages within tumors and the possibility to selectively ablate these cells, have proven the relevance of Lgr5+ cells for cancer progression. On the contrary, the role of Lgr5- cells during this process remains largely unknown. In this review, we explore available evidence pointing towards possible selective advantages of cancer cells organized hierarchically and its resulting cell heterogeneity. Clear evidence of plasticity between cell states, in which loss of Lgr5+ cells can be replenished by dedifferentiation of Lgr5- cells, shows that cell hierarchies could grant adaptive traits to tumors upon changing selective pressures, including those derived from anticancer therapy, as well as during tumor progression to metastasis.

Thulium LASER for endoscopic closure of tracheoesophageal fistula in esophageal atresia's spectrum: An appropriate tool?

PURPOSE: To report our experience with endoscopic Thulium LASER for treatment of recurrent TEF after EA surgery, and for H-Type fistulas. METHODS: A retrospective chart review of consecutive patients undergoing standardized endoscopic closure as first line therapy of recurrent tracheoesophageal fistula (RTEF) and H-type fistula using Thulium LASER, from 2013 to 2019, in a pediatric tertiary care center. Control endoscopic procedure was systematically performed. If persistence of the TEF was noted an external approach was performed. Patient demographics, medical history, symptoms, TEF type, treatment modalities, complications and outcomes were collected. RESULTS: Eleven patients with tracheoesophageal fistula were included: six RTEF after primary repair of esophageal atresia and five H-type fistulas. The average age at endoscopic treatment was 19 months (SD 23 months, range 13 days-63 months). Closure of the fistula after single endoscopic procedure with Thulium LASER was obtained in 3 RTEF (50%) and 1 H-type fistula (20%). Six patients with failure of endoscopic treatment were cured after a single external procedure without any complications. One child, treated for H-type fistula, presented a severe complication of Thulium LASER treatment. Median follow-up after last repair was 24 months (range: 14-72 months). All fistulas were successfully treated. CONCLUSIONS: In H-Type fistula, success rate of Thulium LASER is only 20% and thus should not be used. In contrast, in RTEF, success rate of 50% is achieved, avoiding as many open procedures, and Thulium LASER could be considered as first line treatment. In any case, open surgery is safe and efficient and can be considered as a first-line treatment for H-type fistulas, and as a salvage treatment for endoscopic treatment failures. LEVELS OF EVIDENCE: Level IV.