Fibrolamellar hepatocellular carcinoma: Exploring molecular mechanisms and differentiation pathways to better understand disease outcomes and prognosis

Proteo-metabolomics and patient tumor slice experiments point to amino acid centrality for rewired mitochondria in fibrolamellar carcinoma

Fibrolamellar carcinoma (FLC) is a rare, lethal, early-onset liver cancer with a critical need for new therapeutics. The primary driver in FLC is the fusion oncoprotein, DNAJ-PKAc, which remains challenging to target therapeutically. It is critical, therefore, to expand understanding of the FLC molecular landscape to identify druggable pathways/targets. Here, we perform the most comprehensive integrative proteo-metabolomic analysis of FLC. We also conduct nutrient manipulation, respirometry analyses, as well as key loss-of-function assays in FLC tumor tissue slices from patients. We propose a model of cellular energetics in FLC pointing to proline anabolism being mediated by ornithine aminotransferase hyperactivity and ornithine transcarbamylase hypoactivity with serine and glutamine catabolism fueling the process. We highlight FLC's potential dependency on voltage-dependent anion channel (VDAC), a mitochondrial gatekeeper for anions including pyruvate. The metabolic rewiring in FLC that we propose in our model, with an emphasis on mitochondria, can be exploited for therapeutic vulnerabilities.

Acroamine A, a 2-Amino Adenine Alkaloid from the Marine Soft Coral Acrozoanthus australiae and Its Semisynthetic Derivatives That Inhibit cAMP-Dependent Protein Kinase A Catalytic Subunit Alpha

A high throughput screen performed to identify catalytic inhibitors of the oncogenic fusion form of cAMP-dependent protein kinase A catalytic subunit alpha (J-PKAcα) found an individual fraction from an organic extract of the marine soft coral Acrozoanthus australiae as active. Bioassay-guided isolation led to the identification of a 2-amino adenine alkaloid acroamine A (1), the first secondary metabolite discovered from this genus and previously reported as a synthetic product. As a naturally occurring protein kinase inhibitor, to unambiguously assign its chemical structure using modern spectroscopic and spectrometric techniques, five N-methylated derivatives acroamines A1-A5 (2-6) were semisynthesized. Three additional brominated congeners A6-A8 (7-9) were also semisynthesized to investigate the structure-activity relationship of the nine compounds as J-PKAcα inhibitors. Compounds 1-9 were tested for J-PKAcα and wild-type PKA inhibitory activities, which were observed exclusively in acroamine A (1) and its brominated analogs (7-9) achieving moderate potency (IC50 2-50 μM) while none of the N-methylated analogs exhibited kinase inhibition.

Fibrolamellar Hepatocellular Carcinoma (FLHCC) in a Young Patient Presenting With Nausea and Vomiting After a Greasy Meal

Fibrolamellar hepatocellular carcinoma (FLHCC) is a rare and distinct subtype of liver cancer, predominantly affecting younger patients without underlying liver diseases. This case report discusses a unique presentation of FLHCC in a 38-year-old male with a past medical history of a well-controlled seizure disorder. The patient presented with nausea, vomiting, and abdominal pain following a fatty meal. Laboratory tests revealed elevated liver enzymes and anemia, and imaging showed a large hepatic lesion. Initial management included a septic workup and broad-spectrum antibiotics. However, a liver biopsy performed subsequently revealed the presence of FLHCC. The patient underwent a successful open right hepatectomy and was managed postoperatively with consideration of his seizure disorder. Follow-up at six months showed a stable postoperative condition without any evidence of recurrence. The diagnosis of FLHCC is challenging due to its rarity and nonspecific presentation. The case emphasizes the importance of considering FLHCC in the differential diagnosis of hepatic lesions, particularly in young patients. Surgical resection remains the primary treatment modality. This case underscores the importance of a thorough evaluation of hepatic lesions, especially in younger patients. It also illustrates the complexities in managing patients with FLHCC, requiring a multidisciplinary approach for optimal outcomes. Further research is necessary to better understand the pathogenesis of FLHCC and to develop more effective treatment strategies.

Organoid models of fibrolamellar carcinoma mutations reveal hepatocyte transdifferentiation through cooperative BAP1 and PRKAR2A loss

Fibrolamellar carcinoma (FLC) is a lethal primary liver cancer, affecting young patients in absence of chronic liver disease. Molecular understanding of FLC tumorigenesis is limited, partly due to the scarcity of experimental models. Here, we CRISPR-engineer human hepatocyte organoids to recreate different FLC backgrounds, including the predominant genetic alteration, the DNAJB1-PRKACA fusion, as well as a recently reported background of FLC-like tumors, encompassing inactivating mutations of BAP1 and PRKAR2A. Phenotypic characterizations and comparisons with primary FLC tumor samples revealed mutant organoid-tumor similarities. All FLC mutations caused hepatocyte dedifferentiation, yet only combined loss of BAP1 and PRKAR2A resulted in hepatocyte transdifferentiation into liver ductal/progenitor-like cells that could exclusively grow in a ductal cell environment. BAP1-mutant hepatocytes represent primed cells attempting to proliferate in this cAMP-stimulating environment, but require concomitant PRKAR2A loss to overcome cell cycle arrest. In all analyses, DNAJB1-PRKACA^fus organoids presented with milder phenotypes, suggesting differences between FLC genetic backgrounds, or for example the need for additional mutations, interactions with niche cells, or a different cell-of-origin. These engineered human organoid models facilitate the study of FLC.

Fibrolamellar carcinoma: Challenging the challenge

Fibrolamellar carcinoma (FLC) is a rare and poorly understood malignancy, which seems to be more prevalent in young patients compared with conventional hepatocellular carcinoma (HCC). Performing prospective clinical trials recruiting patients diagnosed with FLC has proven challenging with scarce data available guiding clinical management. The use of a number of chemotherapy compounds in these patients, including cisplatin, epirubicin, 5-fluorouracil (5-FU) and recombinant interferon α-2B (IFN-α-2B), has been reported in the literature, mainly in the form of case reports. The most promising systemic therapy tested so far is the combination of 5-FU infusion and 3-weekly IFN-α-2B, based on results from a phase II clinical trial. This article provides an overview of our own experience with this treatment schedule for patients with FLC, confirming its activity and treatment-derived benefit in the real world. Current challenges being faced by healthcare professionals treating patients with advanced FLC are discussed, especially the increasingly limited access to IFN-α-2B, which could compromise the access to an active therapy in the coming future, and the difficulties in the development of new treatment options for advanced FLC.

Rare malignant liver tumors in children

Malignant hepatic tumors in children are rare, comprising 1.3% of all pediatric malignancies. Following hepatoblastoma, hepatocellular carcinoma is the second most common. Other malignant hepatic tumors seen in childhood include those of mesenchymal origin including undifferentiated embryonal sarcoma, angiosarcoma, rhabdomyosarcoma and epithelioid hemangioendothelioma, as well as biliary tumors such as cholangiocarcinoma. Diagnosis can be challenging because of their rarity, and the recognition of distinctive imaging features for certain tumors such as epithelioid hemangioendothelioma and biliary rhabdomyosarcoma can focus the differential diagnosis and expedite the diagnostic process. A complete MRI examination with hepatocyte-specific contrast media and diffusion-weighted imaging helps to focus the differential diagnosis, and, although findings are often nonspecific, in some cases typical features on MRI can be helpful in diagnosis. Histopathological analysis is usually required for definitive diagnosis. Hepatic tumors tend to be aggressive, and full staging is imperative to establish disease extent. Significant proportions are not amenable to upfront surgical resection and often require a multimodality approach including neoadjuvant chemotherapy within a multidisciplinary setting. Facilitating complete surgical resection is usually required for better survival. In this review, we emphasize pathology and imaging features for rare liver tumors that are useful in reaching a prompt diagnosis. We also discuss general clinical findings, prognosis and management of these tumors.