Chemoresistance and resistance to targeted therapies in biliary tract cancer: What have we learned?

Strategies to enhance the response of liver cancer to pharmacological treatments

In contrast to other types of cancers, there is no available efficient pharmacological treatment to improve the outcomes of patients suffering from major primary liver cancers, i.e., hepatocellular carcinoma and cholangiocarcinoma. This dismal situation is partly due to the existence in these tumors of many different and synergistic mechanisms of resistance, accounting for the lack of response of these patients, not only to classical chemotherapy but also to more modern pharmacological agents based on the inhibition of tyrosine kinase receptors (TKIs) and the stimulation of the immune response against the tumor using immune checkpoint inhibitors (ICIs). This review summarizes the efforts to develop strategies to overcome this severe limitation, including searching for novel drugs derived from synthetic, semisynthetic, or natural products with vectorial properties against therapeutic targets to increase drug uptake or reduce drug export from cancer cells. Besides, immunotherapy is a promising line of research that is already starting to be implemented in clinical practice. Although less successful than in other cancers, the foreseen future for this strategy in treating liver cancers is considerable. Similarly, the pharmacological inhibition of epigenetic targets is highly promising. Many novel "epidrugs," able to act on "writer," "reader," and "eraser" epigenetic players, are currently being evaluated in preclinical and clinical studies. Finally, gene therapy is a broad field of research in the fight against liver cancer chemoresistance, based on the impressive advances recently achieved in gene manipulation. In sum, although the present is still dismal, there is reason for hope in the non-too-distant future.

Whole-exome sequencing reveals novel cancer genes and actionable targets in biliary tract cancers in primary sclerosing cholangitis

BACKGROUND

People with primary sclerosing cholangitis (PSC) have a 20% lifetime risk of biliary tract cancer (BTC). Using whole-exome sequencing, we characterized genomic alterations in tissue samples from BTC with underlying PSC.

METHODS

We extracted DNA from formalin-fixed, paraffin-embedded tumor and paired nontumor tissue from 52 resection or biopsy specimens from patients with PSC and BTC and performed whole-exome sequencing. Following copy number analysis, variant calling, and filtering, putative PSC-BTC-associated genes were assessed by pathway analyses and annotated to targeted cancer therapies.

RESULTS

We identified 53 candidate cancer genes with a total of 123 nonsynonymous alterations passing filtering thresholds in 2 or more samples. Of the identified genes, 19% had not previously been implicated in BTC, including CNGA3, KRT28, and EFCAB5. Another subset comprised genes previously implicated in hepato-pancreato-biliary cancer, such as ARID2, ELF3, and PTPRD. Finally, we identified a subset of genes implicated in a wide range of cancers such as the tumor suppressor genes TP53, CDKN2A, SMAD4, and RNF43 and the oncogenes KRAS, ERBB2, and BRAF. Focal copy number variations were found in 51.9% of the samples. Alterations in potential actionable genes, including ERBB2, MDM2, and FGFR3 were identified and alterations in the RTK/RAS (p = 0.036), TP53 (p = 0.04), and PI3K (p = 0.043) pathways were significantly associated with reduced overall survival.

CONCLUSIONS

In this exome-wide characterization of PSC-associated BTC, we delineated both PSC-specific and universal cancer genes. Our findings provide opportunities for a better understanding of the development of BTC in PSC and could be used as a platform to develop personalized treatment approaches.

Fasting-induced RNF152 resensitizes gallbladder cancer cells to gemcitabine by inhibiting mTORC1-mediated glycolysis

Abnormal mTORC1 activation by the lysosomal Ragulator complex has been implicated in cancer and glycolytic metabolism associated with drug resistance. Fasting upregulates RNF152 and mediates the metabolic status of cells. We report that RNF152 regulates mTORC1 signaling by targeting a Ragulator subunit, p18, and attenuates gemcitabine resistance in gallbladder cancer (GBC). We detected levels of RNF152 and p18 in tissues and undertook mechanistic studies using activators, inhibitors, and lentivirus transfections. RNF152 levels were significantly lower in GBC than in adjacent non-cancer tissues. Fasting impairs glycolysis, induces gemcitabine sensitivity, and upregulates RNF152 expression. RNF152 overexpression increases the sensitivity of GBC cells to gemcitabine, whereas silencing RNF152 has the opposite effect. Fasting-induced RNF152 ubiquitinates p18, resulting in proteasomal degradation. RNF152 deficiency increases the lysosomal localization of p18 and increases mTORC1 activity, to promote glycolysis and decrease gemcitabine sensitivity. RNF152 suppresses mTORC1 activity to inhibit glycolysis and enhance gemcitabine sensitivity in GBC.

Establishment and Characterization of a New Intrahepatic Cholangiocarcinoma Cell Line, ICC-X2

Background

Intrahepatic cholangiocarcinoma (ICC) is an aggressive malignant tumor of the biliary tract that is prone to recurrence and metastasis and is characterized by poor sensitivity to chemotherapy and overall prognosis. For these reasons, there is an urgent need to understand its pathological mechanisms and develop effective treatments. To address this challenge, the establishment of suitable preclinical models is critical.

Methods

Fresh ICC tissue samples were used for primary culture and subculture. The cell line was evaluated by cell proliferation assays, clonal formation assays, karyotype analysis, and short tandem repeat (STR) analysis. Drug resistances against oxaliplatin, paclitaxel, gemcitabine and 5-fluorouracil (5-FU) were evaluated by CCK-8 assay. Subcutaneous injection of 1 × 106 cells to three BALB/c nude mice was conducted for xenograft studies. The hematoxylin and eosin (H&E) staining was used to detect the pathological status of the cell line. The expression of biomarkers CK7, CK19, Ki-67, E-cadherin and vimentin was determined by immunocytochemistry assay.

Results

A new ICC cell line named ICC-X2 was successfully established. Like ICC-X3 established using the same patient's metastatic tumor, the cell line has been continuously cultured in vitro for more than a year and has been passaged more than 100 times. ICC-X2 retained the typical biliary epithelial morphology. The population doubling time of ICC-X2 is 48 h. The cells demonstrated an abnormal nearly tetraploid karyotype. The STR analysis confirmed that ICC-X2 was highly consistent with the primary tumor tissue and not cross-contaminated by existing cell lines. ICC-X2 cells positively expressed CK7, CK19, E-cadherin, and vimentin, and the positive expression of Ki-67 in ICC-X2 cells was 40%. The ICC-X2 cells exhibited a strong clonogenic ability. The drug sensitivity test indicated that ICC-X2 was sensitive to oxaliplatin and paclitaxel, but naturally resistant to gemcitabine and 5-FU. ICC-X2 was rapidly able to form transplanted tumors in vivo after subcutaneous inoculation in nude mice.

Conclusions

ICC-X2 is an excellent experimental model that can be used for studying the occurrence, development, and metastasis of ICC and investigating the mechanism of tumor drug resistance.

New trends in diagnosis and management of gallbladder carcinoma

Gallbladder (GB) carcinoma, although relatively rare, is the most common biliary tree cholangiocarcinoma with aggressiveness and poor prognosis. It is closely associated with cholelithiasis and long-standing large (> 3 cm) gallstones in up to 90% of cases. The other main predisposing factors for GB carcinoma include molecular factors such as mutated genes, GB wall calcification (porcelain) or mainly mucosal microcalcifications, and GB polyps ≥ 1 cm in size. Diagnosis is made by ultrasound, computed tomography (CT), and, more precisely, magnetic resonance imaging (MRI). Preoperative staging is of great importance in decision-making regarding therapeutic management. Preoperative staging is based on MRI findings, the leading technique for liver metastasis imaging, enhanced three-phase CT angiography, or magnetic resonance angiography for major vessel assessment. It is also necessary to use positron emission tomography (PET)-CT or 18F-FDG PET-MRI to more accurately detect metastases and any other occult deposits with active metabolic uptake. Staging laparoscopy may detect dissemination not otherwise found in 20%-28.6% of cases. Multimodality treatment is needed, including surgical resection, targeted therapy by biological agents according to molecular testing gene mapping, chemotherapy, radiation therapy, and immunotherapy. It is of great importance to understand the updated guidelines and current treatment options. The extent of surgical intervention depends on the disease stage, ranging from simple cholecystectomy (T1a) to extended resections and including extended cholecystectomy (T1b), with wide lymph node resection in every case or IV-V segmentectomy (T2), hepatic trisegmentectomy or major hepatectomy accompanied by hepaticojejunostomy Roux-Y, and adjacent organ resection if necessary (T3). Laparoscopic or robotic surgery shows fewer postoperative complications and equivalent oncological outcomes when compared to open surgery, but much attention must be paid to avoiding injuries. In addition to surgery, novel targeted treatment along with immunotherapy and recent improvements in radiotherapy and chemotherapy (neoadjuvant-adjuvant capecitabine, cisplatin, gemcitabine) have yielded promising results even in inoperable cases calling for palliation (T4). Thus, individualized treatment must be applied.

ELF3 promotes gemcitabine resistance through PKMYT1/CDK1 signaling pathway in gallbladder cancer

BACKGROUND

Gemcitabine is the standard treatment for gallbladder cancer (GBC) patients, and the development of resistance frequently limits its efficacy. However, the molecular features and mechanisms of gemcitabine resistance (Gem-R) in GBC cells remain unknown. Herein, we aimed to explore the role of ELF3 in Gem-R of GBC, including the underlying mechanisms.

METHODS

RNA sequencing was used to screen the essential genes related to the generation of Gem-R in GBC tissues. The correlation between Gem-R and ELF3 expression was identified in GDSC, GEO database, GBC tissues, and 3 GBC cell lines. Immunohistochemical staining, quantitative real-time polymerase chain reaction, and western blot were used to examine the expression of ELF3, PKMYT1, and CDK1. Luciferase reporter assays were used to identify the binding site of ELF3 in the PKMYT1 promoter region. CCK-8 assay and clonogenic survival assays were used to evaluate the sensitivity of gemcitabine in GBC cells. A GBC xenograft model was used to evaluate the influence of ELF3 on the therapeutic effect of gemcitabine.

RESULTS

A consistently positive correlation between ELF3 expression and Gem-R, both in newly generated GBC RNA-seq data and in the datasets from GDSC and GEO. Gem-R in GBC cells was facilitated by ELF3 overexpression, whereas ELF3 knockdown had the opposite effect. In vivo experiments further proved that reducing ELF3 expression promoted the gemcitabine sensitivity of GBC cells and extended the survival time of mice that received orthotopic xenografted tumors. Mechanistically, ELF3 upregulated PKMYT1 expression by interacting with the DNA binding region of PKMYT1 in GBC cells, thereby promoting the phosphorylation of CDK1 and inducing Gem-R. Treatment with a combination of the PKMYT1 shRNA and gemcitabine significantly reduced the growth of GBC cells induced by overexpression of ELF3 in vitro and in vivo.

CONCLUSIONS

ELF3/PKMYT1/CDK1 axis significantly regulates Gem-R to GBC cells and may represent a promising drug target for treating GBC patients.

Novel precision therapies for cholangiocarcinoma: an overview of clinical trials

INTRODUCTION

The treatment landscape of biliary cancers is rapidly changing. Inhibitors against the actionable targets FGFR and IDH1 are now being included in the treatment guidelines of multiple countries for patients with advanced cholangiocarcinoma. However, there remains an unmet need in identifying the mechanisms of resistance and treatment strategies involving possible tumor sequencing.

AREAS COVERED

In this review article, we address clinical trials evaluating FGFR, IDH, BRAF and HER2 inhibitors in advanced cholangiocarcinoma. We also review the mechanisms of resistance described thus far and approaches to overcome them. Articles selected for this review were based on reported studies indexed in PubMed (2010-2022).

EXPERT OPINION

Precision medicine in biliary cancers has already been incorporated into the treatment landscape of the disease in many countries. Fusions of FGFR2 and mutations in IDH1 are the first drivers with targetable treatments approved in these cancers. HER2 and BRAF would be the next drivers with possible tumor-agnostic or cholangiocarcinoma-specific approvals. The advent of ctDNA could improve the accessibility of sequencing and recruitment in these clinical trials. However, limitations of detecting fusions should be considered and addressed in these platforms.

pH and Redox-Dual Sensitive Chitosan Nanoparticles Having Methyl Ester and Disulfide Linkages for Drug Targeting against Cholangiocarcinoma Cells

The aim of this study is to prepare pH- and redox-sensitive nanoparticles for doxorubicin (DOX) delivery against DOX-resistant HuCC-T1 human cholangiocarcinoma (CCA) cells. For this purpose, L-histidine methyl ester (HIS) was attached to chitosan oligosaccharide (COS) via dithiodipropionic acid (abbreviated as ChitoHISss). DOX-incorporated nanoparticles of ChitoHISss conjugates were fabricated by a dialysis procedure. DOX-resistant HuCC-T1 cells were prepared by repetitive exposure of HuCC-T1 cells to DOX. ChitoHISss nanoparticles showed spherical morphology with a small diameter of less than 200 nm. The acid pH and glutathione (GSH) addition induced changes in the size distribution pattern of ChitoHISss nanoparticles from a narrow/monomodal distribution pattern to a wide/multimodal pattern and increased the fluorescence intensity of the nanoparticle solution. These results indicate that a physicochemical transition of nanoparticles can occur in an acidic pH or redox state. The more acidic the pH or the higher the GSH concentration the higher the drug release rate was, indicating that an acidic environment or higher redox states accelerated drug release from ChitoHISss nanoparticles. Whereas free DOX showed decreased anticancer activity at DOX-resistant HuCC-T1 cells, DOX-incorporated ChitoHISss nanoparticles showed dose-dependent anticancer activity. Intracellular delivery of DOX-incorporated ChitoHISss nanoparticles was relatively increased at an acidic pH and in the presence of GSH, indicating that DOX-incorporated ChitoHISss nanoparticles have superior acidic pH- and redox-sensitive behavior. In an in vivo tumor xenograft model, DOX-incorporated ChitoHISss nanoparticles were specifically delivered to tumor tissues and then efficiently inhibited tumor growth. We suggest that ChitoHISss nanoparticles are a promising candidate for treatment of CCA.