Cell Cycle Changes after Glioblastoma Stem Cell Irradiation: The Major Role of RAD51

“Glioma Stem Cells” (GSCs) are known to play a role in glioblastoma (GBM) recurrence. Homologous recombination (HR) defects and cell cycle checkpoint abnormalities can contribute concurrently to the radioresistance of GSCs. DNA repair protein RAD51 homolog 1 (RAD51) is a crucial protein for HR and its inhibition has been shown to sensitize GSCs to irradiation. The aim of this study was to examine the consequences of ionizing radiation (IR) for cell cycle progression in GSCs. In addition, we intended to assess the potential effect of RAD51 inhibition on cell cycle progression. Five radiosensitive GSC lines and five GSC lines that were previously characterized as radioresistant were exposed to 4Gy IR, and cell cycle analysis was done by fluorescence-activated cell sorting (FACS) at 24, 48, 72, and 96 h with or without RAD51 inhibitor. Following 4Gy IR, all GSC lines presented a significant increase in G2 phase at 24 h, which was maintained over 72 h. In the presence of RAD51 inhibitor, radioresistant GSCs showed delayed G2 arrest post-irradiation for up to 48 h. This study demonstrates that all GSCs can promote G2 arrest in response to radiation-induced DNA damage. However, following RAD51 inhibition, the cell cycle checkpoint response differed. This study contributes to the characterization of the radioresistance mechanisms of GSCs, thereby supporting the rationale of targeting RAD51-dependent repair pathways in view of radiosensitizing GSCs

High Intra- and Inter-Tumoral Heterogeneity of RAS Mutations in Colorectal Cancer

Approximately 30% of patients with wild type RAS metastatic colorectal cancer are non-responders to anti-epidermal growth factor receptor monoclonal antibodies (anti-EGFR mAbs), possibly due to undetected tumoral subclones harboring RAS mutations. The aim of this study was to analyze the distribution of RAS mutations in different areas of the primary tumor, metastatic lymph nodes and distant metastasis. A retrospective cohort of 18 patients with a colorectal cancer (CRC) was included in the study. Multiregion analysis was performed in 60 spatially separated tumor areas according to the pathological tumor node metastasis (pTNM) staging and KRAS, NRAS and BRAF mutations were tested using pyrosequencing. In primary tumors, intra-tumoral heterogeneity for RAS mutation was found in 33% of cases. Inter-tumoral heterogeneity for RAS mutation between primary tumors and metastatic lymph nodes or distant metastasis was found in 36% of cases. Moreover, 28% of tumors had multiple RAS mutated subclones in the same tumor. A high proportion of CRCs presented intra- and/or inter-tumoral heterogeneity, which has relevant clinical implications for anti-EGFR mAbs prescription. These results suggest the need for multiple RAS testing in different parts of the same tumor and/or more sensitive techniques

Variants du facteur VII de la coagulation : quelle thromboplastine utiliser pour doser son activité ?

International audienceLe déficit constitutionnel en facteur VII de la coagulation (FVII), caractérisé par une grande hétérogénéité clinique et biologique, a pour particularité de présenter des variants FVII dont le dosage de l’activité (FVII:C) varie selon la thromboplastine utilisée. Il s’agit en particulier des variants p.Arg364Gln et p.Arg139Gln, très fréquents sur le continent africain et dans le sud de l’Europe, mais la liste de ces variants s’allonge avec la caractérisation moléculaire des déficits en FVII. Les hypothèses physiopathologiques reposent sur la différence de la séquence protéique des facteurs tissulaires humains ou de lapin composant les thromboplastines. L’analyse des phénotypes cliniques associés conforte l’option consistant à retenir la valeur obtenue avec une thromboplastine humaine, c’est-à-dire composée du facteur tissulaire physiologique. Il est ainsi recommandé de contrôler toute valeur de FVII:C dans le cadre d’un déficit constitutionnel en FVII afin de ne pas surtraiter ces patients

Cell Cycle Changes after Glioblastoma Stem Cell Irradiation: The Major Role of RAD51

“Glioma Stem Cells” (GSCs) are known to play a role in glioblastoma (GBM) recurrence. Homologous recombination (HR) defects and cell cycle checkpoint abnormalities can contribute concurrently to the radioresistance of GSCs. DNA repair protein RAD51 homolog 1 (RAD51) is a crucial protein for HR and its inhibition has been shown to sensitize GSCs to irradiation. The aim of this study was to examine the consequences of ionizing radiation (IR) for cell cycle progression in GSCs. In addition, we intended to assess the potential effect of RAD51 inhibition on cell cycle progression. Five radiosensitive GSC lines and five GSC lines that were previously characterized as radioresistant were exposed to 4Gy IR, and cell cycle analysis was done by fluorescence-activated cell sorting (FACS) at 24, 48, 72, and 96 h with or without RAD51 inhibitor. Following 4Gy IR, all GSC lines presented a significant increase in G2 phase at 24 h, which was maintained over 72 h. In the presence of RAD51 inhibitor, radioresistant GSCs showed delayed G2 arrest post-irradiation for up to 48 h. This study demonstrates that all GSCs can promote G2 arrest in response to radiation-induced DNA damage. However, following RAD51 inhibition, the cell cycle checkpoint response differed. This study contributes to the characterization of the radioresistance mechanisms of GSCs, thereby supporting the rationale of targeting RAD51-dependent repair pathways in view of radiosensitizing GSCs

HSP110 as a Diagnostic but Not a Prognostic Biomarker in Colorectal Cancer With Microsatellite Instability

Determination of microsatellite instability (MSI) using molecular test and deficient mismatch repair (dMMR) using immunohistochemistry (IHC) has major implications on colorectal cancer (CRC) management. The HSP110 T 17 microsatellite has been reported to be more monomorphic than the common markers used for MSI determination. Large deletion of HSP110 T 17 has been associated with efficacy of adjuvant chemotherapy in dMMR/MSI CRCs. The aim of this study was to evaluate the interest of HSP110 deletion/expression as a diagnostic tool of dMMR/MSI CRCs and a predictive tool of adjuvant chemotherapy efficacy. All patients with MSI CRC classified by molecular testing were included in this multicenter prospective cohort ( n = 381). IHC of the 4 MMR proteins was carried out. HSP110 expression was carried out by IHC ( n = 343), and the size of HSP110 T 17 deletion was determined by PCR (n = 327). In the 293 MSI CRCs with both tests, a strong correlation was found between the expression of HSP110 protein and the size of HSP110 T 17 deletion. Only 5.8% of MSI CRCs had no HSP110 T 17 deletion ( n = 19/327). HSP110 T 17 deletion helped to re-classify 4 of the 9 pMMR/MSI discordance cases as pMMR/MSS cases. We did not observe any correlation between HSP110 expression or HSP110 T 17 deletion size with time to recurrence in patients with stage II and III CRC, treated with or without adjuvant chemotherapy. HSP110 is neither a robust prognosis marker nor a predictor tool of adjuvant chemotherapy efficacy in dMMR/MSI CRC. However, HSP110 T 17 is an interesting marker, which may be combined with the other pentaplex markers to identify discordant cases between MMR IHC and MSI

Pathological and Molecular Characteristics of Colorectal Cancer with Brain Metastases

Background: Colorectal cancers (CRC) with brain metastases (BM) are scarcely described. The main objective of this study was to determine the molecular profile of CRC with BM. Methods: We included 82 CRC patients with BM. KRAS, NRAS, BRAF and mismatch repair (MMR) status were investigated on primary tumors (n = 82) and BM (n = 38). ALK, ROS1, cMET, HER-2, PD-1, PD-L1, CD3 and CD8 status were evaluated by immunohistochemistry, and when recommended, by fluorescence in situ hybridization. Results: In primary tumors, KRAS, NRAS and BRAF mutations were observed in 56%, 6%, and 6% of cases, respectively. No ROS1, ALK and cMET rearrangement was detected. Only one tumor presented HER-2 amplification. Molecular profiles were mostly concordant between BM and paired primary tumors, except for 9% of discordances for RAS mutation. CD3, CD8, PD-1 and PD-L1 expressions presented some discordance between primary tumors and BM. In multivariate analysis, multiple BM, lung metastases and PD-L1+ tumor were predictive of poor overall survival. Conclusions: CRCs with BM are associated with high frequency of RAS mutations and significant discordance for RAS mutational status between BM and paired primary tumors. Multiple BM, lung metastases and PD-L1+ have been identified as prognostic factors and can guide therapeutic decisions for CRC patients with BM

Cardiovascular risk stratification in hemodialysis patients in the era of highly sensitive troponins: should we choose between hs-troponin I and hs-troponin T?

International audienceNew highly sensitive (hs) assays have challenged the interpretation of cardiac troponins (cTn). The present study was designed to evaluate simultaneously conventional cTnT and cTnI together with their corresponding highly sensitive determinations in stable hemodialysis (HD) patients. Ability of cTn to stratify HD patient risk was assessed

The role of genetic factors in patients with hepatocellular carcinoma and iron overload - a prospective series of 234 patients

International audienceBACKGROUND & AIMS:Iron overload (IO) in HFE-related hereditary haemochromatosis is associated with increased risk of liver cancer. This study aimed to investigate the role of other genes involved in hereditary IO among patients with hepatocellular carcinoma (HCC).METHODS:Patients with HCC diagnosed in our institution were included in this prospective study. Those with ferritin levels ≥300 μg/L (males) or ≥200 μg/L (females) and/or transferrin saturation ≥50% (males) or ≥45% (females) had liver iron concentration (LIC) evaluated by MRI. HFE C282Y and H63D mutations were screened. Genetic analyses of genes involved in hereditary IO (HFE, HJV/HFE2, HAMP, TFR2, SLC40A1, GNPAT) were performed in patients with increased LIC.RESULTS:A total of 234 patients were included; 215 (92%) had common acquired risk factors of HCC (mainly alcoholism or chronic viral hepatitis). 119 patients had abnormal iron parameters. Twelve (5.1%) were C282Y homozygotes, three were compound C282Y/H63D heterozygotes. LIC was measured by MRI in 100 patients. Thirteen patients with a LIC>70 μmol/g were enrolled in further genetic analyses: two unrelated patients bore the HAMP:c.-153C>T mutation at the heterozygous state, which is associated with increased risk of IO and severe haemochromatosis. Specific haplotypes of SLC40A1 were also studied.CONCLUSIONS:Additional genetic risk factors of IO were found in 18 patients (7.7%) among a large series of 234 HCC patients. Screening for IO and the associated at-risk genotypes in patients who have developed HCC, is useful for both determining etiologic diagnosis and enabling family screening and possibly primary prevention in relatives