Cannabinoids, a class of compounds derived from Cannabis sativa L., have recently become more widely accessible for public consumption in the form of diverse cannabis products, in parallel with weakening the measures that so far restricted their availability. The US Food and Drug Administration has approved several cannabis-derived drugs for management of various diseases as well as chemotherapy-induced nausea and vomiting. Besides the attenuation of adverse effects of chemotherapy, numerous reports about cannabinoid-mediated anticancer effects further motivate cancer patients to support their therapy with such products. Here we present a set of preclinical data with human cell culture models, suggesting that cannabidiol and cannabis extracts may effectively counteract the anticancer effects of the clinically widely used standard-of-care platinum-based drugs. We show that even low concentrations of cannabinoids reduced the toxicity of cisplatin, oxaliplatin, and carboplatin, an effect which was accompanied by decreased platinum adduct formation and a set of commonly used molecular markers. Mechanistically, our results excluded the possibility that the observed enhanced survival of cancer cells was mediated transcriptionally. Instead, trace metal analyses strongly indicate an inhibitory impact of cannabinoids on intracellular platinum accumulation, thereby implicating changes in cellular transport and/or retention of these drugs as the likely cause of the observed biological effects. Our study raises the possibility that the desirable effect of counteracting adverse effects of chemotherapy might, at least for some cannabinoids, reflect impaired cellular availability, and consequently attenuation of the anticancer effects of platinum drugs. DATA AVAILABILITY: All data supporting the conclusions are available in the article and supplementary files. Raw data are available upon request from the corresponding author.
DNA-protein interactions play an essential role in many regulatory mechanisms such as replication, transcription or translation and are responsible for the maintenance of the genome integrity. Isolation, identification and subsequent characterization of the biological function of DNA binding proteins propose insight into the pathological mechanisms that underlie various diseases. This review brings an overview of methods used for isolation and identification of DNA binding proteins (DNA-affinity chromatography coupled with quantitative proteomics and mass spectrometry) and subsequent methods for the characterization of their biological functions (fluorescence microscopy). Principles, advantages and disadvantages of individual methods are briefly discussed.
Replication stress (RS) fuels genomic instability and cancer development and may contribute to aging, raising the need to identify factors involved in cellular responses to such stress. Here, we present a strategy for identification of factors affecting the maintenance of common fragile sites (CFSs), which are genomic loci that are particularly sensitive to RS and suffer from increased breakage and rearrangements in tumors. A DNA probe designed to match the high flexibility island sequence typical for the commonly expressed CFS (FRA16D) was used as specific DNA affinity bait. Proteins significantly enriched at the FRA16D fragment under normal and replication stress conditions were identified using stable isotope labeling of amino acids in cell culture-based quantitative mass spectrometry. The identified proteins interacting with the FRA16D fragment included some known CFS stabilizers, thereby validating this screening approach. Among the hits from our screen so far not implicated in CFS maintenance, we chose Xeroderma pigmentosum protein group C (XPC) for further characterization. XPC is a key factor in the DNA repair pathway known as global genomic nucleotide excision repair (GG-NER), a mechanism whose several components were enriched at the FRA16D fragment in our screen. Functional experiments revealed defective checkpoint signaling and escape of DNA replication intermediates into mitosis and the next generation of XPC-depleted cells exposed to RS. Overall, our results provide insights into an unexpected biological role of XPC in response to replication stress and document the power of proteomics-based screening strategies to elucidate mechanisms of pathophysiological significance.
- MeSH
- Chromatography, Affinity MeSH
- DNA-Binding Proteins physiology MeSH
- Chromosome Fragile Sites MeSH
- Cell Cycle Checkpoints MeSH
- Humans MeSH
- DNA Repair physiology MeSH
- Proteomics methods MeSH
- DNA Replication physiology MeSH
- Xeroderma Pigmentosum MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
