Usefulness of bile as a biomarker via ferroptosis and cysteine prenylation in cholangiocarcinoma; role of diagnosis and differentiation from benign biliary disease

Gut microbiota regulates the ALK5/NOX1 axis by altering glutamine metabolism to inhibit ferroptosis of intrahepatic cholangiocarcinoma cells

Intrahepatic cholangiocarcinoma (ICC) is a kind of hepatobiliary tumor that is increasing in incidence and mortality. The gut microbiota plays a role in the onset and progression of cancer, however, the specific mechanism by which the gut microbiota acts on ICC remains unclear. In this study, feces and plasma from healthy controls and ICC patients were collected for 16S rRNA sequencing or metabolomics analysis. Gut microbiota analysis showed that gut microbiota abundance and biodiversity were altered in ICC patients compared with controls. Plasma metabolism analysis showed that the metabolite glutamine content of the ICC patient was significantly higher than that of the controls. KEGG pathway analysis showed that glutamine plays a vital role in ICC. In addition, the use of antibiotics in ICC animals further confirmed that changes in gut microbiota affect changes in glutamine. Further experiments showed that supplementation with glutamine inhibited ferroptosis and downregulated ALK5 and NOX1 expression in HuCCT1 cells. ALK5 overexpression or NOX1 overexpression increased NOX1, p53, PTGS2, ACSL4, LPCAT3, ROS, MDA and Fe2+ and decreased FTH1, SLC7A11 and GSH. Knockdown of NOX1 suppressed FIN56-induced ferroptosis. In vivo, supplementation with glutamine promoted tumor growth. Overexpression of ALK5 repressed tumor growth and induced ferroptosis in nude mice, which could be reversed by the addition of glutamine. Our results suggested that the gut microbiota altered glutamine metabolism to inhibit ferroptosis in ICC by regulating the ALK5/NOX1 axis.

Recent Advancement in Diagnosis of Biliary Tract Cancer through Pathological and Molecular Classifications

Biliary tract cancers (BTCs), including intrahepatic, perihilar, and distal cholangiocarcinomas, as well as gallbladder cancer, are a diverse group of cancers that exhibit unique molecular characteristics in each of their anatomic and pathological subtypes. The pathological classification of BTCs compromises distinct growth patterns, including mass forming, periductal infiltrating, and intraductal growing types, which can be identified through gross examination. The small-duct and large-duct types of intrahepatic cholangiocarcinoma have been recently introduced into the WHO classification. The presentation of typical clinical symptoms, as well as the extensive utilization of radiological, endoscopic, and molecular diagnostic methods, is thoroughly detailed in the description. To overcome the limitations of traditional tissue acquisition methods, new diagnostic modalities are being explored. The treatment landscape is also rapidly evolving owing to the emergence of distinct subgroups with unique molecular alterations and corresponding targeted therapies. Furthermore, we emphasize the crucial aspects of diagnosing BTC in practical clinical settings.

Diagnostic Role of Bile Pigment Components in Biliary Tract Cancer

Bile pigment, bilirubin, and biliverdin concentrations may change as a results of biliary tract cancer (BTC) altering the mechanisms of radical oxidation and heme breakdown. We explored whether changes in bile pigment components could help distinguish BTC from benign biliary illness by evaluating alterations in patients with BTC. We collected bile fluid from 15 patients with a common bile duct stone (CBD group) and 63 individuals with BTC (BTC group). We examined the bile fluid's bilirubin, biliverdin reductase (BVR), heme oxygenase (HO-1), and bacterial taxonomic abundance. Serum bilirubin levels had no impact on the amounts of bile HO-1, BVR, or bilirubin. In comparison to the control group, the BTC group had considerably higher amounts of HO-1, BVR, and bilirubin in the bile. The areas under the curve for the receiver operating characteristic curve analyses of the BVR and HO-1 were 0.832 (p<0.001) and 0.891 (p<0.001), respectively. Firmicutes was the most prevalent phylum in both CBD and BTC, according to a taxonomic abundance analysis, however the Firmicutes/Bacteroidetes ratio was substantially greater in the BTC group than in the CBD group. The findings of this study showed that, regardless of the existence of obstructive jaundice, biliary carcinogenesis impacts heme degradation and bile pigmentation, and that the bile pigment components HO-1, BVR, and bilirubin in bile fluid have a diagnostic significance in BTC. In tissue biopsies for the diagnosis of BTC, particularly for distinguishing BTC from benign biliary strictures, bile pigment components can be used as additional biomarkers.

Bile liquid biopsy in biliary tract cancer

Biliary tract cancers are heterogeneous in etiology, morphology and molecular characteristics thus impacting disease management. Diagnosis is complex and prognosis poor. The advent of liquid biopsy has provided a unique approach to more thoroughly understand tumor biology in general and biliary tract cancers specifically. Due to their minimally invasive nature, liquid biopsy can be used to serially monitor disease progression and allow real-time monitoring of tumor genetic profiles as well as therapeutic response. Due to the unique anatomic location of biliary tract cancer, bile provides a promising biologic fluid for this purpose. This review focuses on the composition of bile and the use of these various components, ie, cells, extracellular vesicles, nucleic acids, proteins and metabolites as potential biomarkers. Based on the disease characteristics and research status of biliary tract cancer, considerable effort should be made to increase understanding of this disease, promote research and development into early diagnosis, develop efficient diagnostic, therapeutic and prognostic markers.

Implication of Ferroptosis in Cholangiocarcinoma: A Potential Future Target?

Cholangiocarcinoma (CCA), the second most common liver neoplasm, has a poor overall 5-year survival rate of less than 10%. A deeper understanding of the molecular pathogenesis contributing to CCA progression is essential for developing better therapeutic approaches to manage this disease. Ferroptosis, an oxidative iron-dependent form of regulated cell death, has been reported to be involved in tumorigenesis and progression. In particular, ferroptosis and inflammation, which are common issues in cholangiocarcinogenesis and CCA development, might be in concert with disease progression. Notably, the key feature of cancer cells is "iron addiction", which is crucial for the high metabolic demand in carcinogenesis and cancer progression. Additionally, iron metabolism is of great importance in ferroptosis. Moreover, that cancer cells are vulnerable to ferroptosis might be a possible mechanism of CCA development. Although the underlying mechanism of how ferroptosis is implicated in CCA development requires further investigation, developing a new strategy combined with a pro-ferroptotic treatment would be an exciting CCA treatment approach in the future.

The Emerging Role of Ferroptosis in Liver Cancers

Liver cancer represents a global health challenge with worldwide growth. Hepatocellular carcinoma (HCC) is the most common type of liver cancer. Indeed, approximately 90% of HCC cases have a low survival rate. Moreover, cholangiocarcinoma (CC) is another malignant solid tumor originating from cholangiocytes, the epithelial cells of the biliary system. It is the second-most common primary liver tumor, with an increasing course in morbidity and mortality. Tumor cells always show high metabolic levels, antioxidant modifications, and an increased iron uptake to maintain unlimited growth. In recent years, alterations in iron metabolism have been shown to play an important role in the pathogenesis of HCC. Several findings show that a diet rich in iron can enhance HCC risk. Hence, elevated iron concentration inside the cell may promote the development of HCC. Growing evidence sustains that activating ferroptosis may potentially block the proliferation of HCC cells. Even in CC, it has been shown that ferroptosis plays a crucial role in the treatment of tumors. Several data confirmed the inhibitory effect in cell growth of photodynamic therapy (PDT) that can induce reactive oxygen species (ROS) in CC, leading to an increase in malondialdehyde (MDA) and a decrease in intracellular glutathione (GSH). MDA and GSH depletion/modulation are crucial in inducing ferroptosis, suggesting that PDT may have the potential to induce this kind of cell death through these ways. A selective induction of programmed cell death in cancer cells is one of the main treatments for malignant tumors; thus, ferroptosis may represent a novel therapeutic strategy against HCC and CC.

Research progress of bile biomarkers and their immunoregulatory role in biliary tract cancers

Biliary tract cancers (BTCs), including cholangiocarcinoma and gallbladder carcinoma, originate from the biliary epithelium and have a poor prognosis. Surgery is the only choice for cure in the early stage of disease. However, most patients are diagnosed in the advanced stage and lose the chance for surgery. Early diagnosis could significantly improve the prognosis of patients. Bile has complex components and is in direct contact with biliary tract tumors. Bile components are closely related to the occurrence and development of biliary tract tumors and may be applied as biomarkers for BTCs. Meanwhile, arising evidence has confirmed the immunoregulatory role of bile components. In this review, we aim to summarize and discuss the relationship between bile components and biliary tract cancers and their ability as biomarkers for BTCs, highlighting the role of bile components in regulating immune response, and their promising application prospects.

Isocitrate dehydrogenase 1 mutation in cholangiocarcinoma impairs tumor progression by sensitizing cells to ferroptosis

The present study intends to clarify the hypothesis that isocitrate dehydrogenase 1 (IDH1) mutation in cholangiocarcinoma impairs tumor progression by sensitizing cells to ferroptosis through the in vitro and in vivo experiments. Cholangiocarcinoma RBE cell line was transfected with IDH1 R132C mutation plasmids and treated with erastin to induce ferroptosis, which were then microscopically photographed. Cell viability rate was calculated by trypan blue staining. The lipid ROS level was determined by using flow cytometer. The BALB/c nude mice were injected subcutaneously with IDH1 knockout (KO), WT, or R132C mutation cell line, followed by injecting erastin intraperitoneally. The tumor tissue was surgically separated for the measurement of tumor volume and weight. The results showed that IDH1 mutant RBE cell line are sensitive to erastin-induced ferroptosis, evidenced by the increased number of propidium iodide-positive cells, the decreased cell viability, and increased lipid ROS level. However, current targeted inhibitors of IDH1 mutation (AG120 and IDH305) reversed these effects caused by IDH1 mutation. The in vivo experiment showed that IDH1 mutation in cholangiocarcinoma impairs tumor progression by sensitizing cells to erastin-induced ferroptosis. This study indicated that IDH1 mutation in cholangiocarcinoma impairs tumor progression by sensitizing cells to erastin-induced ferroptosis.

A Novel Ferroptosis-Related 4-Gene Prognostic Signature for Cholangiocarcinoma and Photodynamic Therapy

Cholangiocarcinoma is the second most common malignant tumor in the hepatobiliary system. Compared with data on hepatocellular carcinoma, fewer public data and prognostic-related studies on cholangiocarcinoma are available, and effective prognostic prediction methods for cholangiocarcinoma are lacking. In recent years, ferroptosis has become an important subject of tumor research. Some studies have indicated that ferroptosis plays an important role in hepatobiliary cancers. However, the prediction of the prognostic effect of ferroptosis in patients with cholangiocarcinoma has not been reported. In addition, many reports have described the ability of photodynamic therapy (PDT), a potential therapy for cholangiocarcinoma, to regulate ferroptosis by generating reactive oxygen species (ROS). By constructing ferroptosis scores, the prognoses of patients with cholangiocarcinoma can be effectively predicted, and potential gene targets can be discovered to further enhance the efficacy of PDT. In this study, gene expression profiles and clinical information (TCGA, E-MTAB-6389, and GSE107943) of patients with cholangiocarcinoma were collected and divided into training sets and validation sets. Then, a model of the ferroptosis gene signature was constructed using least absolute shrinkage and selection operator (LASSO)-penalized Cox regression analysis. Furthermore, through the analysis of RNA-seq data after PDT treatment of cholangiocarcinoma, PDT-sensitive genes were obtained and verified by immunohistochemistry staining and Western blot. The results of this study provide new insight for predicting the prognosis of cholangiocarcinoma and screening target genes that enhance the efficacy of PDT.

Liquid Biopsy from Bile-Circulating Tumor DNA in Patients with Biliary Tract Cancer

Simple Summary

Utilization of cell free DNA for diagnosing and monitoring patients with biliary tract cancers is emerging and promising. The strength of the present study is in its description of a novel approach using bile rather than blood or tissue samples, which is particularly relevant in biliary tract cancers. This paper largely serves as a proof of concept that ctDNA from bile is potentially feasible.

Abstract

Although liquid biopsy of blood is useful for cancer diagnosis and prediction of prognosis, diagnostic and prognostic value of ctDNA in bile fluid for BTCs are not clear yet. To determine whether liquid biopsy for circulating tumor DNA (ctDNA) can replace tissue biopsy when assessing somatic mutations in biliary tract cancers (BTCs). Bile samples were obtained from 42 patients with BTC. Matched formalin-fixed paraffin-embedded (FFPE) samples were obtained from 20 of these patients and matched plasma samples from 16 of them. Droplet digital PCR (ddPCR) was used for detection KRAS somatic mutation. KRAS mutations were identified in the bile ctDNA of 20 of 42 (48%) patients. Patients with mutant KRAS showed significantly worse survival than those with wild-type KRAS (2-year survival rates: 0% vs. 55.5%, respectively; p = 0.018). There was 80.0% mutational concordance between the paired bile ctDNA and FFPE samples, and 42.9% between the plasma and FFPE samples. On transcriptomic sequencing of one set of paired bile and FFPE samples, expression level of KRAS-associated signaling oncogenes in the bile and tissue samples showed a strong positive correlation (r = 0.991, p < 0.001). Liquid biopsy of bile reliably detect mutational variants within the bile ctDNA of BTC patients. These results suggest that bile is an effective biopsy fluid for ctDNA analysis.

Comprehensive analysis of new prognostic signature based on ferroptosis-related genes in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is an aggressive tumor and the most common subtype of RCC. Ferroptosis is a novel form of regulated cell death, and ferroptosis-related genes (FRGs) have been associated with the prognosis of patients with certain cancers. However, the detailed prognostic correlation between FRGs and ccRCC has not yet been elucidated. To address this, the current study used The Cancer Genome Atlas (TCGA) dataset to explore 64 FRGs and determine their prognostic value in ccRCC. Results showed that 52 out of the 64 genes displayed significantly different expression levels in tumor tissue, and 35 out of the 52 differentially expressed genes (DEGs) were associated with overall survival. Subsequently, a four-gene prognostic signature (CD44, DPP4, NCOA4 and SLC7A11) was constructed and could successfully distinguish ccRCC patients with different prognosis in TCGA train and test sets. Furthermore, clinical ccRCC samples from our medical center were used to verify the application value of the new prognostic signature through immunohistochemistry and quantitative real-time polymerase chain reaction (qRT-PCR). Biological functional analysis implied that immune-related functions and pathways were enriched in the TCGA cohort and the immune status scores were significantly different between high- and low-risk sets. These results suggest that the four ferroptosis-related regulatory genes can act as reliable prognostic biomarkers of ccRCC, and might be exploited as potential targets of therapeutic strategies.