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Oncogenic KRAS Requires Complete Loss of BAP1 Function for Development of Murine Intrahepatic Cholangiocarcinoma.

ABSTRACT: Intrahepatic cholangiocarcinoma (ICC) is a primary biliary malignancy that harbors a dismal prognosis. Oncogenic mutations of KRAS and loss-of-function mutations of BRCA1-associated protein 1 (BAP1) have been identified as recurrent somatic alterations in ICC. However, an autochthonous genetically engineered mouse model of ICC that genocopies the co-occurrence of these mutations has never been developed. By crossing Albumin-Cre mice bearing conditional alleles of mutant Kras and/or floxed Bap1, Cre-mediated recombination within the liver was induced. Mice with hepatic expression of mutant Kras^G12D alone (KA), bi-allelic loss of hepatic Bap1 (B^homoA), and heterozygous loss of Bap1 in conjunction with mutant Kras^G12D expression (B^hetKA) developed primary hepatocellular carcinoma (HCC), but no discernible ICC. In contrast, mice with homozygous loss of Bap1 in conjunction with mutant Kras^G12D expression (B^homoKA) developed discrete foci of HCC and ICC. Further, the median survival of B^homoKA mice was significantly shorter at 24 weeks when compared to the median survival of ≥40 weeks in B^hetKA mice and approximately 50 weeks in B^homoA and KA mice (p < 0.001). Microarray analysis performed on liver tissue from KA and B^homoKA mice identified differentially expressed genes in the setting of BAP1 loss and suggests that deregulation of ferroptosis might be one mechanism by which loss of BAP1 cooperates with oncogenic Ras in hepato-biliary carcinogenesis. Our autochthonous model provides an in vivo platform to further study this lethal class of neoplasm.

SUBMITTER: Marcus R

PROVIDER: S-EPMC8616431 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:IntroductionIntrahepatic cholangiocarcinoma (ICC) is a rare hepatobiliary cancer characterized by a poor prognosis and a limited response to conventional therapies. Currently chemotherapy is the only therapeutic option for patients with Stage IV ICC. Due to the poor response rate, there is an urgent need to identify novel molecular targets to develop novel effective therapies. Precision oncology tests utilizing targeted next-generation sequencing (NGS) platforms have rapidly entered into clinical practice. Profiling the genome and transcriptome of cancer to identify potentially targetable oncogenic pathways may guide the clinical care of the patient.Case presentationWe present a 56-year-old male patient affected with metastatic ICC, whose cancer underwent several precision oncology tests by different NGS platforms. A novel BAP1 mutation (splice site c.581-17_585del22) and a RAD21 amplification were identified by a commercial available platform on a metastatic lesion. No germline BAP1 mutations were identified. Several lines of evidences indicate that PARP inhibitor administration might be an effective treatment in presence of BAP1 and/or RAD21 alterations since both BAP1 and RAD21 are involved in the DNA repair pathway, BAP1 interacts with BRCA1 and BRCA1-mediated DNA repair pathway alterations enhance the sensitivity to PARP inhibitor administration. In this case, after failing conventional therapies, patient was treated with PARP inhibitor olaparib. The patient had a partial response according to RECIST criteria with an overall survival of 37.2 months from the time of diagnosis of his ICC. Following 11.0 months on olaparib treatment, sustained stable disease control is ongoing. The patient is still being treated with olaparib and no significant toxicity has been reported.ConclusionThese findings have clinical relevance since we have shown PARP inhibitor as a potential treatment for ICC patients harboring BAP1 deletion and RAD21 amplification. We have also highlighted the utility of NGS platforms to identify targetable mutations within a cancer.

Project description:ImportanceKRAS variants are associated with tumor progression; however, the prevalence of KRAS variant subtypes and their association with survival and recurrence in patients with intrahepatic cholangiocarcinoma (ICC) after curative resection are largely unknown.ObjectiveTo explore the prognostic association of KRAS variant subtypes with survival and recurrence in patients with ICC.Design, setting, and participantsIn this cohort study, patients who underwent curative resection for ICC from January 2009 through December 2016 at a single hospital in China were recruited, and whole-exome sequencing, targeted sequencing, and Sanger sequencing were performed to identify KRAS variants. Kaplan-Meier and log-rank tests were used to compare overall survival (OS) and disease-free survival (DFS). Univariate and multivariate analyses were performed using the Cox proportional hazards regression model. Data were analyzed from April 2020 to January 2021.InterventionsHepatectomy in patients with ICC.Main outcomes and measuresThe association of KRAS variant subtypes with OS and DFS.ResultsOf 1024 included patients with ICC, 621 (60.6%) were male, and the mean (SD) age was 59.2 (10.2) years. A total of 14 different subtypes of KRAS somatic variants affecting 127 patients (12.4%) were identified. G12D was the most frequent allele in this cohort, accounting for 55 of 127 identified KRAS variants (43.3%), followed by G12V (25 [19.7%]), G12C (9 [7.1%]), and G13D (8 [6.3%]). Compared with patients with wild-type KRAS, patients with variant KRAS were more likely to have high levels of carbohydrate antigen 19-9 (92 of 127 [72.4%] vs 546 of 897 [60.9%]; P = .01) and γ-glutamyltransferase (72 of 127 [56.7%] vs 420 of 897 [46.8%]; P = .04). Multivariable analysis revealed that G12 KRAS variants but not non-G12 KRAS variants were independently associated with worse OS (hazard ratio [HR], 1.69; 95% CI, 1.31-2.18; P < .001) and DFS (HR, 1.47; 95% CI, 1.16-1.88; P = .002). Among the patients with G12 KRAS variants, the G12V KRAS variant was the strongest prognostic determinant for the worst OS (HR, 3.05; 95% CI, 1.94-4.79; P < .001) and DFS (HR, 1.79; 95% CI, 1.13-2.85; P = .01).Conclusions and relevanceIn this cohort study, the distribution of KRAS variant subtypes was characterized in a large cohort of patients with ICC from China. The presence of G12 KRAS variants but not non-G12 KRAS variants was associated with worse survival and increased risk of recurrence. Patients with the G12V variant exhibited the worst outcomes in the whole cohort.

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Oncogenic KRAS Requires Complete Loss of BAP1 Function for Development of Murine Intrahepatic Cholangiocarcinoma.

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