Mickael Mathieu, Prerna R Nepali, James Russell, Hadi Askarifirouzjaei, Melis Baltaci, Simon N Powell, John Humm, Joseph O Deasy, Adriana Haimovitz-Friedman
{"title":"ASMase is Essential for the Immune Response to Partial-Tumor Radiation Exposure.","authors":"Mickael Mathieu, Prerna R Nepali, James Russell, Hadi Askarifirouzjaei, Melis Baltaci, Simon N Powell, John Humm, Joseph O Deasy, Adriana Haimovitz-Friedman","doi":"10.33594/000000726","DOIUrl":null,"url":null,"abstract":"<p><strong>Background/aims: </strong>Tumor response to radiation is thought to depend on the direct killing of tumor cells. Our laboratory has called this into question. Firstly, we showed that the biology of the host, specifically the endothelial expression of acid sphingomyelinase (ASMase), was critical in determining tumor radiocurability. Secondly, we have shown that the immune system can enhance radiation response by allowing a complete tumor control in hemi-irradiated tumors. In this paper, we focus on the integration of these two findings.</p><p><strong>Methods: </strong>We used Lewis Lung Carcinoma (LLC) cells, injected in the flank of either: (i) ASMase knockout or (ii) WT of matched background (sv129xBl/6) or (iii) C57Bl/6 mice. Radiation therapy (RT) was delivered to 50% or 100% of the LLC tumor volume. Tumor response, immune infiltration (CD8<sup>+</sup> T cells), ICAM-1, and STING activation were measured. Radiotherapy was also combined with methyl-cyclodextrin, to inhibit the ASMase-mediated formation of ceramide-enriched lipid rafts.</p><p><strong>Results: </strong>We recapitulated our previous finding, namely that tumor hemi-irradiation was sufficient for tumor control in the LLC/C57Bl/6 model. However, in ASMase KO mice hemi-irradiation was ineffective. Likewise, pharmacological inhibition of ASMase significantly reduced the tumor response to hemi-irradiation. Further, we demonstrated elevated ICAM-1 expression, increased levels of CD8<sup>+</sup> T cells, ICAM-1, and STING activation in tumors growing in C57Bl/6 mice, as well as the ASMase WT strain. However, no such changes were seen in tumors growing in ASMase KO mice.</p><p><strong>Conclusion: </strong>ASMase and ceramide generation are necessary to mediate a radiation-induced anti-tumor immune response <i>via</i> STING activation.</p>","PeriodicalId":9845,"journal":{"name":"Cellular Physiology and Biochemistry","volume":null,"pages":null},"PeriodicalIF":2.5000,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Cellular Physiology and Biochemistry","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.33594/000000726","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"CELL BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Background/aims: Tumor response to radiation is thought to depend on the direct killing of tumor cells. Our laboratory has called this into question. Firstly, we showed that the biology of the host, specifically the endothelial expression of acid sphingomyelinase (ASMase), was critical in determining tumor radiocurability. Secondly, we have shown that the immune system can enhance radiation response by allowing a complete tumor control in hemi-irradiated tumors. In this paper, we focus on the integration of these two findings.
Methods: We used Lewis Lung Carcinoma (LLC) cells, injected in the flank of either: (i) ASMase knockout or (ii) WT of matched background (sv129xBl/6) or (iii) C57Bl/6 mice. Radiation therapy (RT) was delivered to 50% or 100% of the LLC tumor volume. Tumor response, immune infiltration (CD8+ T cells), ICAM-1, and STING activation were measured. Radiotherapy was also combined with methyl-cyclodextrin, to inhibit the ASMase-mediated formation of ceramide-enriched lipid rafts.
Results: We recapitulated our previous finding, namely that tumor hemi-irradiation was sufficient for tumor control in the LLC/C57Bl/6 model. However, in ASMase KO mice hemi-irradiation was ineffective. Likewise, pharmacological inhibition of ASMase significantly reduced the tumor response to hemi-irradiation. Further, we demonstrated elevated ICAM-1 expression, increased levels of CD8+ T cells, ICAM-1, and STING activation in tumors growing in C57Bl/6 mice, as well as the ASMase WT strain. However, no such changes were seen in tumors growing in ASMase KO mice.
Conclusion: ASMase and ceramide generation are necessary to mediate a radiation-induced anti-tumor immune response via STING activation.
期刊介绍:
Cellular Physiology and Biochemistry is a multidisciplinary scientific forum dedicated to advancing the frontiers of basic cellular research. It addresses scientists from both the physiological and biochemical disciplines as well as related fields such as genetics, molecular biology, pathophysiology, pathobiochemistry and cellular toxicology & pharmacology. Original papers and reviews on the mechanisms of intracellular transmission, cellular metabolism, cell growth, differentiation and death, ion channels and carriers, and the maintenance, regulation and disturbances of cell volume are presented. Appearing monthly under peer review, Cellular Physiology and Biochemistry takes an active role in the concerted international effort to unravel the mechanisms of cellular function.