Cytoplasmic RRM1 activation as an acute response to gemcitabine treatment is involved in drug resistance of pancreatic cancer cells

Initial Low-Dose Hydroxyurea and Anagrelide Combination in Essential Thrombocythemia: Comparable Response with Lower Toxicity

Background and Objectives: Essential thrombocythemia (ET) is a myeloproliferative neoplasm that overproduces platelets and is associated with life-threatening thrombosis. Medical cytoreduction either with hydroxyurea (HU) or anagrelide (AG) is widely used, but drug intolerance or resistance are major concerns. Low-dose combination of HU and AG as an alternative strategy has been explored in various studies. It showed comparable response with acceptable toxicity in second-line settings for patients who experienced side effects from prior monotherapy. In this study, we evaluated the efficacy and safety of upfront combination for ET patients. Materials and Methods: From January 2018 to June 2022, a total of 241 ET patients with intermediate to high risk were enrolled. We identified 21 patients with initial drug combinations and compared treatment outcomes and adverse events (AEs) between combination and monotherapy groups. Results: The median age was 62 years old (range, 26-87) and median platelet count was 912 × 109/L (range, 520-1720). Overall treatment response did not exhibit significant differences between the groups, although there was a trend towards a lower response rate in patients treated with AG alone at 3 months post-treatment (AG + HU, 85.7% vs. AG alone, 75.4%, p = 0.068). AEs of any grade occurred in 52.3% of the combination group, 44.3% of the HU monotherapy group, and 43.4% of the AG single group, respectively. Of note was that the HU plus AG combination group suffered a lower incidence of grade 3-4 AEs compared to the other two groups, with statistical significance (p = 0.008 for HU monotherapy vs. combination therapy and p < 0.01 for AG monotherapy vs. combination therapy). Conclusions: Our findings demonstrated that the upfront low-dose combination approach showed feasible clinical outcomes with significantly lower severe AEs compared to conventional monotherapy. These results may offer valuable insights to clinicians for future prospective investigations.

4'-Ethynyl-2'-Deoxycytidine (EdC) Preferentially Targets Lymphoma and Leukemia Subtypes by Inducing Replicative Stress

Anticancer nucleosides are effective against solid tumors and hematologic malignancies, but typically are prone to nucleoside metabolism resistance mechanisms. Using a nucleoside-specific multiplexed high-throughput screening approach, we discovered 4'-ethynyl-2'-deoxycytidine (EdC) as a third-generation anticancer nucleoside prodrug with preferential activity against diffuse large B-cell lymphoma (DLBCL) and acute lymphoblastic leukemia (ALL). EdC requires deoxycytidine kinase (DCK) phosphorylation for its activity and induces replication fork arrest and accumulation of cells in S-phase, indicating it acts as a chain terminator. A 2.1Å cocrystal structure of DCK bound to EdC and UDP reveals how the rigid 4'-alkyne of EdC fits within the active site of DCK. Remarkably, EdC was resistant to cytidine deamination and SAMHD1 metabolism mechanisms and exhibited higher potency against ALL compared with FDA-approved nelarabine. Finally, EdC was highly effective against DLBCL tumors and B-ALL in vivo. These data characterize EdC as a preclinical nucleoside prodrug candidate for DLBCL and ALL.

Prognostic value of RRM1 and its effect on chemoresistance in pancreatic cancer

PURPOSE

Pancreatic cancer (PC) remains a lethal disease, and gemcitabine resistance is prevalent. However, the biomarkers suggestive of gemcitabine resistance remain unclear.

METHODS

Bioinformatic tools identified ribonucleotide reductase catalytic subunit M1 (RRM1) in gemcitabine-related datasets. A cox regression model revealed the predictive value of RRM1 with clinical features. An external clinical cohort confirmed the prognostic value of RRM1. RRM1 expression was validated in gemcitabine-resistant cells in vitro and in orthotopic PC model. CCK8, flow cytometry, transwell migration, and invasion assays were used to explore the effect of RRM1 on gemcitabine-resistant cells. The CIBERSORT algorithm investigated the impact of RRM1 on immune infiltration.

RESULTS

The constructed nomogram based on RRM1 effectively predicted prognosis and was further validated. Moreover, patients with higher RRM1 had shorter overall survival. RRM1 expression was significantly higher in PC tissue and gemcitabine-resistant cells in vitro and in vivo. RRM1 knockdown reversed gemcitabine resistance, inhibited migration and invasion. The infiltration levels of CD4 + T cells, CD8 + T cells, neutrophils, and plasma cells correlated markedly with RRM1 expression, and communication between tumor and immune cells probably depends on NF-κB/mTOR signaling.

CONCLUSION

RRM1 may be a potential marker for prognosis and a target marker for gemcitabine resistance in PC.

Ribonucleotide reductase M2 (RRM2): Regulation, function and targeting strategy in human cancer

Ribonucleotide reductase M2 (RRM2) is a small subunit in ribonucleotide reductases, which participate in nucleotide metabolism and catalyze the conversion of nucleotides to deoxynucleotides, maintaining the dNTP pools for DNA biosynthesis, repair, and replication. RRM2 performs a critical role in the malignant biological behaviors of cancers. The structure, regulation, and function of RRM2 and its inhibitors were discussed. RRM2 gene can produce two transcripts encoding the same ORF. RRM2 expression is regulated at multiple levels during the processes from transcription to translation. Moreover, this gene is associated with resistance, regulated cell death, and tumor immunity. In order to develop and design inhibitors of RRM2, appropriate strategies can be adopted based on different mechanisms. Thus, a greater appreciation of the characteristics of RRM2 is a benefit for understanding tumorigenesis, resistance in cancer, and tumor microenvironment. Moreover, RRM2-targeted therapy will be more attention in future therapeutic approaches for enhancement of treatment effects and amelioration of the dismal prognosis.

Molecular Profile of Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is a relatively uncommon but highly aggressive primary liver cancer that originates within the liver. The aim of this study is to review the molecular profile of intrahepatic cholangiocarcinoma and its implications for prognostication and decision-making. This comprehensive characterization of ICC tumors sheds light on the disease's underlying biology and offers a foundation for more personalized treatment strategies. This is a narrative review of the prognostic and therapeutic role of the molecular profile of ICC. Knowing the molecular profile of tumors helps determine prognosis and support certain target therapies. The molecular panel in ICC helps to select patients for specific therapies, predict treatment responses, and monitor treatment responses. Precision medicine in ICC can promote improvement in prognosis and reduce unnecessary toxicity and might have a significant role in the management of ICC in the following years. The main mutations in ICC are in tumor protein p53 (TP53), Kirsten rat sarcoma virus (KRAS), isocitrate dehydrogenase 1 (IDH1), and AT-rich interactive domain-containing protein 1A (ARID1A). The rate of mutations varies significantly for each population. Targeting TP53 and KRAS is challenging due to the natural characteristics of these genes. Different stages of clinical studies have shown encouraging results with inhibitors of mutated IDH1 and target therapy for ARID1A downstream effectors. Fibroblast growth factor receptor 2 (FGFR2) fusions are an important target in patients with ICC. Immune checkpoint blockade can be applied to a small percentage of ICC patients. Molecular profiling in ICC represents a groundbreaking approach to understanding and managing this complex liver cancer. As our comprehension of ICC's molecular intricacies continues to expand, so does the potential for offering patients more precise and effective treatments. The integration of molecular profiling into clinical practice signifies the dawn of a new era in ICC care, emphasizing personalized medicine in the ongoing battle against this malignancy.

Pan-Cancer Drug Response Prediction Using Integrative Principal Component Regression

The pursuit of precision oncology heavily relies on large-scale genomic and pharmacological data garnered from preclinical cancer model systems such as cell lines. While cell lines are instrumental in understanding the interplay between genomic programs and drug response, it well-established that they are not fully representative of patient tumors. Development of integrative methods that can systematically assess the commonalities between patient tumors and cell-lines can help bridge this gap. To this end, we introduce the Integrative Principal Component Regression (iPCR) model which uncovers both joint and model-specific structured variations in the genomic data of cell lines and patient tumors through matrix decompositions. The extracted joint variation is then used to predict patient drug responses based on the pharmacological data from preclinical models. Moreover, the interpretability of our model allows for the identification of key driver genes and pathways associated with the treatment-specific response in patients across multiple cancers. We demonstrate that the outputs of the iPCR model can assist in inferring both model-specific and shared co-expression networks between cell lines and patients. We show that iPCR performs favorably compared to competing approaches in predicting patient drug responses, in both simulation studies and real-world applications, in addition to identifying key genomic drivers of cancer drug responses.

Combination drug screen targeting glioblastoma core vulnerabilities reveals pharmacological synergisms

BACKGROUND

Pharmacological synergisms are an attractive anticancer strategy. However, with more than 5000 approved-drugs and compounds in clinical development, identifying synergistic treatments represents a major challenge.

METHODS

High-throughput screening was combined with target deconvolution and functional genomics to reveal targetable vulnerabilities in glioblastoma. The role of the top gene hit was investigated by RNA interference, transcriptomics and immunohistochemistry in glioblastoma patient samples. Drug combination screen using a custom-made library of 88 compounds in association with six inhibitors of the identified glioblastoma vulnerabilities was performed to unveil pharmacological synergisms. Glioblastoma 3D spheroid, organotypic ex vivo and syngeneic orthotopic mouse models were used to validate synergistic treatments.

FINDINGS

Nine targetable vulnerabilities were identified in glioblastoma and the top gene hit RRM1 was validated as an independent prognostic factor. The associations of CHK1/MEK and AURKA/BET inhibitors were identified as the most potent amongst 528 tested pairwise drug combinations and their efficacy was validated in 3D spheroid models. The high synergism of AURKA/BET dual inhibition was confirmed in ex vivo and in vivo glioblastoma models, without detectable toxicity.

INTERPRETATION

Our work provides strong pre-clinical evidence of the efficacy of AURKA/BET inhibitor combination in glioblastoma and opens new therapeutic avenues for this unmet medical need. Besides, we established the proof-of-concept of a stepwise approach aiming at exploiting drug poly-pharmacology to unveil druggable cancer vulnerabilities and to fast-track the identification of synergistic combinations against refractory cancers.

FUNDING

This study was funded by institutional grants and charities.

Recent findings regarding the synergistic effects of emodin and its analogs with other bioactive compounds: Insights into new mechanisms

CONTEXT

Emodin is a natural bioactive ingredient mainly extracted from traditional Chinese herbs. Increasing lines of evidence suggest that emodin and its analogs exert notable synergistic pharmacological effects with other bioactive compounds.

OBJECTIVE

This review provides an overview of the pharmacological activity of emodin and its analogs in combination with other physiologically active substances, describes the related molecular mechanisms, and discusses future prospects in this field.

METHODS

Information from multiple scientific databases, such as PubMed, the China Knowledge Resource Integrated Database from the China National Knowledge Infrastructure (CNKI), the Web of Science, Google Scholar, and Baidu Scholar, was collected between January 2006 and August 2022. The subject terms used in the literature search were emodin, pharmaceutical activities, analogs, aloe emodin, rhein, and synergistic effects.

RESULTS

The comprehensive literature analysis suggested that combinations of emodin or its analogs with other bioactive compounds exert notable synergistic anticancer, anti-inflammatory, and antimicrobial effects and that such combinations improve glucose and lipid metabolism and central nervous system diseases.

DISCUSSION AND CONCLUSIONS

Further assessments of the dose-effect relationship and the differences in the efficacy of emodin or its analogs with other bioactive compounds among various modes of administration are needed, and a drug safety evaluation of these combinations needs to be carefully performed. Future studies should also focus on determining the optimal drug combinations for specific diseases.

RRM1 is mediated by histone acetylation through gemcitabine resistance and contributes to invasiveness and ECM remodeling in pancreatic cancer

The invasiveness of pancreatic cancer and its resistance to anticancer drugs define its malignant potential, and are considered to affect the peritumoral microenvironment. Cancer cells with resistance to gemcitabine exposed to external signals induced by anticancer drugs may enhance their malignant transformation. Ribonucleotide reductase large subunit M1 (RRM1), an enzyme in the DNA synthesis pathway, is upregulated during gemcitabine resistance, and its expression is associated with worse prognosis for pancreatic cancer. However, the biological function of RRM1 is unclear. In the present study, it was demonstrated that histone acetylation is involved in the regulatory mechanism related to the acquisition of gemcitabine resistance and subsequent RRM1 upregulation. The current in vitro study indicated that RRM1 expression is critical for the migratory and invasive potential of pancreatic cancer cells. Furthermore, a comprehensive RNA sequencing analysis showed that activated RRM1 induced marked changes in the expression levels of extracellular matrix‑related genes, including N‑cadherin, tenascin‑C and COL11A. RRM1 activation also promoted extracellular matrix remodeling and mesenchymal features, which enhanced the migratory invasiveness and malignant potential of pancreatic cancer cells. The present results demonstrated that RRM1 has a critical role in the biological gene program that regulates the extracellular matrix, which promotes the aggressive malignant phenotype of pancreatic cancer.

A Brief Review on Chemoresistance; Targeting Cancer Stem Cells as an Alternative Approach

The acquisition of resistance to traditional chemotherapy and the chemoresistant metastatic relapse of minimal residual disease both play a key role in the treatment failure and poor prognosis of cancer. Understanding how cancer cells overcome chemotherapy-induced cell death is critical to improve patient survival rate. Here, we briefly describe the technical approach directed at obtaining chemoresistant cell lines and we will focus on the main defense mechanisms against common chemotherapy triggers by tumor cells. Such as, the alteration of drug influx/efflux, the enhancement of drug metabolic neutralization, the improvement of DNA-repair mechanisms, the inhibition of apoptosis-related cell death, and the role of p53 and reactive oxygen species (ROS) levels in chemoresistance. Furthermore, we will focus on cancer stem cells (CSCs), the cell population that subsists after chemotherapy, increasing drug resistance by different processes such as epithelial-mesenchymal transition (EMT), an enhanced DNA repair machinery, and the capacity to avoid apoptosis mediated by BCL2 family proteins, such as BCL-XL, and the flexibility of their metabolism. Finally, we will review the latest approaches aimed at decreasing CSCs. Nevertheless, the development of long-term therapies to manage and control CSCs populations within the tumors is still necessary.

Proteomic Analysis of the Effect of Salmonella Challenge on Broiler Chicken

Salmonella enteritidis is a foodborne pathogen that causes high morbidity in poultry. Proteomic analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS) was used to study the effects of Salmonella infection on spleen proteome in broiler chickens. Day-old broilers were assigned to control (CON; n = 60) or Salmonella challenge (CON−SE; n = 60), and gavaged with Tryptic soy agar broth or SE. A subset of chicks was euthanized on D3 and D7 (n = 4/group/day) and the spleen was removed, and rapidly frozen, subsequently proteome was measured using label-free LC-MS/MS. Protein spectra were mapped to Gallus gallus Uniprot database. Differentially abundant proteins (DAP; FDR < 0.05) between days and treatments were identified using ANOVA. Cecal content of Salmonella in CON−SE was 3.37 log10 CFU/g and CON were negative. Across the 16 samples, 2625 proteins were identified. Proteins that decreased in abundance between days mediated cell cycle progression, while those that increased in abundance function in cytoskeleton and mRNA processing. SE infection caused an increase in proteins that mediated redox homeostasis, lysosomal activities, and energy production, while proteins decreased in abundance-mediated developmental progression. Proteomic signatures of spleen suggest SE infection was metabolically costly, and energy was diverted from normal developmental processes to potentiate disease resistance mechanisms.

High Glucose Promotes Pancreatic Ductal Adenocarcinoma Gemcitabine Resistance and Invasion through Modulating ROS/MMP-3 Signaling Pathway

Pancreatic ductal adenocarcinoma (PDA) is often concomitant with diabetes mellitus, which mainly manifests as an increased blood glucose level. Previous studies revealed that diabetic status reduced the survival and blunted gemcitabine sensitivity in PDA patients. This study is aimed at analyzing the mechanism of elevated gemcitabine resistance and cancer invasion ability under high glucose environment. We selected 129 patients with 22 surgical resected samples from 2015 to 2021, who underwent pancreatic surgery in Huashan Hospital. The gene expression and clinical data of PDA were obtained from The Cancer Genome Atlas (TCGA) website and were analyzed by R software. Cell viability assays and flow cytometry were applied to detect gemcitabine sensitivity and apoptosis levels in pancreatic cancer cells. Wound healing and Transwell tests were used to analyze the invasion and metastasis of cancer cells. Streptozotocin (STZ) was used to establish a hyperglycemic mouse model for the in vivo study. In this study, diabetic PDA gemcitabine users showed reduced survival compared to euglycemic PDA gemcitabine users. Clinical samples and laboratory studies revealed that MMP-3 expression was associated with glucose concentration and diabetic status. Elevated MMP-3 expression was positively related to cancer invasion and gemcitabine resistance in PDA cells and gemcitabine resistant PDA cells. Blocking MMP-3 expression inhibited gemcitabine resistance and cancer progression in cellular and animal models. MMP-3 was closely related to the expression of RRM1, a gemcitabine metabolism-related gene. Reactive oxygen species (ROS) level increased under higher glucose concentrations and was mediated by NOX4. ROS determined the MMP-3 expression in pancreatic cancer cells. Inhibiting NOX4 expression effectively suppressed MMP-3 expression, gemcitabine resistance, and cancer invasion. In conclusion, a high glucose environment induces gemcitabine resistance and cancer invasion via ROS/MMP-3 signaling pathway. MMP-3 can be a potential novel target for suppressing gemcitabine resistance and invasion in PDA.