{"doi":"10.1111/srt.13332","title":"Radiation therapy produces microvesicle particle release in HaCaT keratinocytes","abstract":"As cancer treatments experience technological advancements, radiation therapy (RT) provides a foundational and essential modality for the treatment of various malignancies. Ionizing radiation (IR), a form of RT, is tailored to individual patients during their cancer care and delivered directly at cancer to kill tumor cells while attempting to spare normal tissue. Notably, as the doses of radiation increase, IR has been shown to be damaging to skin and nearby organs. A common side effect of IR is radiation dermatitis, characterized by erythema, edema, and desquamation.1 IR also has immune modulatory effects ranging from immunostimulatory to immunosuppressive.2, 3 The exact mechanism(s) by which RT to the skin results in local and systemic effects remains unclear, making prevention, diagnosis, and treatment difficult. Studies, including ours, have shown that exposure to environmental carcinogens, pollutants, cigarette smoke, UV radiation, and IR generates reactive oxygen species (ROS). Notably, such ROS-generating pro-oxidative stressors within the cell microenvironment produce a class of potent phospholipid mediators, platelet-activating factor (PAF), and PAF-like agonists (reviewed in Ref. [4]). PAF receptor (PAFR) is a G protein–coupled receptor that has been shown to be involved in mediating both local and systemic immune modulatory responses of PAF agonists.4 Previous studies by our group have also demonstrated that IR can generate high levels of PAF and oxidized glycerophosphocholines with PAFR agonistic activity in multiple tumor cell lines as well as in human subjects undergoing RT.5 One of the hallmarks of the pro-oxidative stress response is the release of subcellular microvesicle particles (MVP) from various cell types. These MVPs play a role in intercellular communication and the regulation of immune responses associated with PAF through the release of various bioactive components, including cytokines and other lipids that play a vital role in cell-to-cell communications.6 Moreover, studies have highlighted the involvement of acid sphingomyelinase (aSMase) in the production of MVP in response to multiple agents.7, 8 Of importance, IR has been demonstrated to result in aSMase activation.9 Given that IR has been shown to induce PAF agonists,5 which are known to trigger MVP release in keratinocytes8, 10, 11 as well as the MVP-generating enzyme aSMase,9 our current study was designed to test the hypothesis that IR at various doses can generate increased MVP release in skin keratinocytes. Of note, a previous published report indicated that IR can generate MVP release in the human keratinocyte cell line HaCaT.12 The present studies were designed to assess the roles of the PAFR and aSMase in this process. To that end, HaCaT cells (human keratinocytes), and our model of the PAFR-negative human nasopharyngeal epithelioid cell KB that was transduced with the MSCV2.1 retroviral blank vector, KBM cells (PAFR-negative), or the MSCV2.1 vector containing PAFR cDNA, KBP cells (PAFR-positive) were treated with IR, and the release of MVPs was measured. Moreover, the ability of the aSMase inhibitor, imipramine to block this MVP response was assessed. HaCaT cells were grown as previously described8 and dosed with IR at either no treatment 0 Gy (Sham), 2 Gy, and 5 Gy, achieved using a Varian TrueBeam radiotherapy system, and confirmed by dosimetry. This HaCaT cell line was also treated with PAFR agonist N-methyl carbamoyl PAF (CPAF) and the PAFR-independent phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), both of which have been shown to induce MVP release.8, 10, 11 A set of cells were also treated with only 0.1% ethanol vehicle in HBSS with BSA. Four hours posttreatment, the supernatants were removed and MVP isolated by centrifugation and measured with a Nanosight NS300 instrument as per our published protocols.8, 10, 11 Shown in Figure 1A, IR at these fluences generated MVP. Untreated (sham) HaCaT cell MVP values ranged from 6","journal":"Skin Research and Technology","year":2023,"id":384881,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":2,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9591,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2023-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1152674,"name":"Shikshita Singh","orcid":null,"position":1,"is_corresponding":false},{"id":937409,"name":"Robert F. Short","orcid":null,"position":2,"is_corresponding":false},{"id":657230,"name":"Christine M. Rapp","orcid":"0000-0001-7114-7796","position":3,"is_corresponding":false},{"id":498578,"name":"Karen M. Henkels","orcid":null,"position":4,"is_corresponding":false},{"id":381164,"name":"Ravi P. Sahu","orcid":"0000-0003-3857-9073","position":5,"is_corresponding":false},{"id":381163,"name":"Jeffrey B. Travers","orcid":"0000-0001-7232-1039","position":6,"is_corresponding":false},{"id":1152673,"name":"Ericson John Torralba","orcid":null,"position":0,"is_corresponding":true}],"reference_count":15,"raw_metadata":null,"created_at":"2026-07-19T01:17:37.110513Z","pmid":"37231923","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}