Search

Pancreatic cancer has one of the highest fatality rates and the poorest prognosis among all cancer types worldwide. Gemcitabine is a commonly used first‐line therapeutic drug for pancreatic cancer; however, the rapid development of resistance to gemcitabine treatment has been observed in numerous patients with pancreatic cancer, and this phenomenon limits the survival benefit of gemcitabine. Adenylosuccinate lyase (ADSL) is a crucial enzyme that serves dual functions in de novo purine biosynthesis, and it has been demonstrated to be associated with clinical aggressiveness, prognosis, and worse patient survival for various cancer types. In the present study, we observed significantly lower ADSL levels in gemcitabine‐resistant cells (PANC‐1/GemR) than in parental PANC‐1 cells, and the knockdown of ADSL significantly increased the gemcitabine resistance of parental PANC‐1 cells. We further demonstrated that ADSL repressed the expression of CARD‐recruited membrane‐associated protein 3 (Carma3), which led to increased gemcitabine resistance, and that nuclear factor erythroid 2‐related factor 2 (Nrf2) regulated ADSL expression in parental PANC‐1 cells. These results indicate that ADSL is a candidate therapeutic target for pancreatic cancer involving gemcitabine resistance and suggest that the Nrf2/ADSL/Carma3 pathway has therapeutic value for pancreatic cancer with acquired resistance to gemcitabine. [ABSTRACT FROM AUTHOR]

Dicer, a cytoplasmic type III RNase, is essential for the maturation of microRNAs (miRNAs) and is implicated in cancer progression and chemoresistance. Our previous research demonstrated that phosphorylation of Dicer at S1016 alters miRNA maturation and glutamine metabolism, contributing to gemcitabine (GEM) resistance in pancreatic ductal adenocarcinoma (PDAC). In this study, we focused on the role of Dicer phosphorylation at S1728/S1852 in GEM-resistant PDAC cells. Using shRNA to knock down Dicer in GEM-resistant PANC-1 (PANC-1 GR) cells, we examined cell viability through MTT and clonogenic assays. We also expressed phosphomimetic Dicer 2E (S1728E/S1852E) and phosphomutant Dicer 2A (S1728A/S1852A) to evaluate their effects on GEM resistance and metabolism. Our results show that phosphorylation at S1728/S1852 promotes GEM resistance by reprogramming glutamine metabolism. Specifically, phosphomimetic Dicer 2E increased intracellular glutamine, driving pyrimidine synthesis and raising dCTP levels, which compete with gemcitabine's metabolites. This metabolic shift enhanced drug resistance. In contrast, phosphomutant Dicer 2A reduced GEM resistance. These findings highlight the importance of Dicer phosphorylation in regulating metabolism and drug sensitivity, offering insights into potential therapeutic strategies for overcoming GEM resistance in pancreatic cancer. [ABSTRACT FROM AUTHOR]

Simple Summary: Cancer is a global health problem caused by uncontrolled cell growth and changes in how cells get and use energy. This review compares cancer's hidden metabolic changes to dark matter and dark energy in the universe, which are mysterious and often ignored. It looks at how cancer cells alter their energy use, such as through the Warburg effect and changes in fat and protein production, driven by genetic mutations. These changes help cancer grow and survive. The review suggests that targeting these metabolic pathways could be a new way to treat cancer. It calls for more research to better understand these changes and develop new therapies by focusing on the "dark energy" that fuels cancer cells. Background: Cancer remains a global health challenge, characterized not just by uncontrolled cell proliferation but also by the complex metabolic reprogramming that underlies its development and progression. Objectives: This review delves into the intricate relationship between cancer and its metabolic alterations, drawing an innovative comparison with the cosmological concepts of dark matter and dark energy to highlight the pivotal yet often overlooked role of metabolic reprogramming in tumor evolution. Methods: It scrutinizes the Warburg effect and other metabolic adaptations, such as shifts in lipid synthesis, amino acid turnover, and mitochondrial function, driven by mutations in key regulatory genes. Results: This review emphasizes the significance of targeting these metabolic pathways for therapeutic intervention, outlining the potential to disrupt cancer's energy supply and signaling mechanisms. It calls for an interdisciplinary research approach to fully understand and exploit the intricacies of cancer metabolism, pointing toward metabolic reprogramming as a promising frontier for developing more effective cancer treatments. Conclusion: By equating cancer's metabolic complexity with the enigmatic nature of dark matter and energy, this review underscores the critical need for innovative strategies in oncology, highlighting the importance of unveiling and targeting the "dark energy" within cancer cells to revolutionize future therapy and research. [ABSTRACT FROM AUTHOR]

HIF-1[alpha], one of the most extensively studied oncogenes, is activated by a variety of microenvironmental factors. The resulting biological effects are thought to depend on its transcriptional activity. The RNAse enzyme Dicer is frequently downregulated in human cancers, which has been functionally linked to enhanced metastatic properties; however, current knowledge of the upstream mechanisms regulating Dicer is limited. In the present study, we identified Dicer as a HIF-1[alpha]-interacting protein in multiple types of cancer cell lines and different human tumors. HIF-1[alpha] downregulated Dicer expression by facilitating its ubiquitination by the E3 ligase Parkin, thereby enhancing autophagy-mediated degradation of Dicer, which further suppressed the maturation of known tumor suppressors, such as the microRNA let-7 and microRNA-200b. Consequently, expression of HIF-1[alpha] facilitated epithelial-mesenchymal transition (EMT) and metastasis in tumor-bearing mice. Thus, this study uncovered a connection between oncogenic HIF-1[alpha] and the tumor-suppressive Dicer. This function of HIF-1[alpha] is transcription independent and occurs through previously unrecognized protein interaction-mediated ubiquitination and autophagic proteolysis., Introduction HIF-1[alpha] is one of the best-studied oncogenes and it transcriptionally regulates genes to facilitate cancer metastasis (1, 2). Although HIF-1[alpha] accumulation was originally identified under hypoxia, as implied by [...]