ABSTRACT
While at the beginning of 2020, the COVID-19 epidemic was spreading at tremendous speed, many scientific teams set to work around the world. The management of severe acute respiratory syndrome coronavirus 2 infections is based on experimental non-specific (symptomatic) or specific (curative) treatments. The vaccine will be the key to long-term immunization.
ABSTRACT
Most solid tumors contain a subfraction of cells with stem/progenitor cell features. Stem cells are naturally chemoresistant suggesting that chronic chemotherapeutic stress may select for cells with increased "stemness". We carried out a comprehensive molecular and functional analysis of six independently selected colorectal cancer (CRC) cell lines with acquired resistance to three different chemotherapeutic agents derived from two distinct parental cell lines. Chronic drug exposure resulted in complex alterations of stem cell markers that could be classified into three categories: 1) one cell line, HT-29/5-FU, showed increased "stemness" and WNT-signaling, 2) three cell lines showed decreased expression of stem cell markers, decreased aldehyde dehydrogenase activity, attenuated WNT-signaling and lost the capacity to form colonospheres and 3) two cell lines displayed prominent expression of ABC transporters with a heterogeneous response for stem cell markers. While WNT-signaling could be attenuated in the HT-29/5-FU cells by the WNT-signaling inhibitors ICG-001 and PKF-118, this was not accompanied by any selective growth inhibitory effect suggesting that the cytotoxic activity of these compounds is not directly linked to WNT-signaling inhibition. We conclude that classical WNT-signaling inhibitors have toxic off-target activities that need to be addressed for clinical development.
Subject(s)
Antineoplastic Agents/pharmacology , Drug Resistance, Neoplasm/drug effects , Neoplastic Stem Cells/drug effects , Wnt Signaling Pathway/drug effects , Blotting, Western , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Camptothecin/analogs & derivatives , Camptothecin/pharmacology , Cell Line, Tumor , Cell Survival/drug effects , Cell Survival/genetics , Colorectal Neoplasms/genetics , Colorectal Neoplasms/metabolism , Colorectal Neoplasms/pathology , Dose-Response Relationship, Drug , Drug Resistance, Neoplasm/genetics , Fluorouracil/pharmacology , Gene Expression Regulation, Neoplastic/drug effects , HCT116 Cells , HT29 Cells , Humans , Hyaluronan Receptors/genetics , Hyaluronan Receptors/metabolism , Irinotecan , Neoplastic Stem Cells/metabolism , Neoplastic Stem Cells/pathology , Organoplatinum Compounds/pharmacology , Oxaliplatin , Protein Isoforms/genetics , Protein Isoforms/metabolism , Pyrimidinones/pharmacology , Reverse Transcriptase Polymerase Chain Reaction , Triazines/pharmacology , Wnt Signaling Pathway/geneticsABSTRACT
Nucleotide excision repair (NER) removes DNA lesions resulting from exposure to UV irradiation or chemical agents such as platinum-based drugs used as anticancer molecules. Pharmacological inhibition of NER is expected to enhance chemosensitivity but nontoxic NER inhibitors are rare. Using a drug repositioning approach, we identify spironolactone (SP), an antagonist of aldosterone, as a potent NER inhibitor. We found that SP promotes a rapid and reversible degradation of XPB, a subunit of transcription/repair factor TFIIH. Such degradation depends both on ubiquitin-activating enzyme and on the 26S proteasome. Supplementation of extracts from SP-treated cells with purified TFIIH restored TFIIH-dependent repair and transcription activities in vitro, demonstrating the specific impact of SP on two fundamental functions of TFIIH. Finally, SP potentiated the cytotoxicity of platinum derivatives toward tumor cells, making it a potential therapeutic and research tool.
