Abstract P2-20-04: Controlling tight junctions in the blood brain barrier (BBB) with artemisinin as a potential adjuvant in the treatment of metastatic disease

Abstract

Abstract Introduction: Brain metastatic disease (BMD) is attributed to significant mortality and morbidity in breast cancer patients. Strict policing of molecular traffic across the blood-brain barrier (BBB) precludes brain parenchymal penetration of most small molecule drugs, chemotherapy included. Consequently, the treatment of BMD remains difficult, particularly if the BBB remains intact during disease progression. Artemisinin has been efficacious in treating multi-drug resistant cerebral malaria likely indicative of an ability to traverse the BBB. Thus, Artemisinin may be able to modulate the restrictive nature of the BBB and provide a potential adjunctive therapy to established drug therapy in the treatment of BMD. Emerging evidence suggests that Artemisinin itself may harbour potent anti-cancer properties. Aim: To investigate in vitro the effect on barrier function in particular paracellular permeability of brain vascular endothelial cells compared to non-brain vascular endothelial cells when treated with Artemisinin. Materials and Methods: Inter-individual BBB differences were modelled using the human brain vascular endothelial cell lines hCMEC-D3, TY09 and TY10. In addition to the brain cell lines, a HUVEC cell line was treated with incremental concentrations of artemisinin. Adhesion, migration and electrical resistance across cellular monolayers were quantified using Electric Cell-Substrate Impedance Sensing (ECIS). Trans- Endo/Epithelial Resistance (TEER) and Paracellular Permeability (PCP) were used to assess barrier function. Immunofluorescence was used to qualitatively assess tight junction (TJ) integrity of all cell lines. RNAseq was used to determine changes in message after treatment with Artemisinin in all 4 cell lines. Results: A significant reduction in electrical resistance across all cell lines was observed when treated with 1mM Artemisinin and may be suggestive of a cytotoxic concentration. In comparison when treated with 0.01mM Artemisinin the electrical resistance decreased which could suggest restrictive barrier properties were enhanced, in addition evidencing Artemisinin may exhibit biphasic activity. The reduction in electrical resistance across the brain endothelial cell lines was significant (p<0.05) but deemed not significant across HUVEC, perhaps mirroring Artemisinin’s pharmacological action at differing vascular interfaces in vivo. Higher Artemisinin concentrations significantly reduced TEER across the brain cell lines and increased paracellular permeability, the same trends were observed in HUVEC. IF demonstrated that Artemisinin was able to effect changes in TJ protein location which supports the hypothesis that Artemisinin reduces barrier function across the brain endothelial lines, suggested by an increased permeability in the presence of Artemisinin. Electrical resistance across all cell lines significantly reduced when treated with 1mM Artemisinin. When compared to negative control, there was a significant decrease in electrical resistance across all cell lines treated with 1mM Artemisinin. RNAseq comparisons revealed that in TY10 cells, 1167 genes were upregulated and 94 downregulated in comparison to HUVEC where 185 and 0 genes were up or downregulated respectively and that in all 3 brain endothelial cell lines that the TJ protein CLDN5 exhibited a significant reduction in expression at gene level (p=0.03). Conclusion: The results demonstrate that Artemisinin may have the capacity to transiently increase or decrease the permeability of the BBB. Therefore, Artemisinin may have a role in facilitating drug delivery to the cerebral parenchyma providing potential therapeutic benefit for the treatment of BMD or other related neurological conditions difficult to treat due to the BBB. Citation Format: Emily Appadurai, Fiona Ruge, Andrew Sanders, Wen G Jiang, Tracey A. Martin. Controlling tight junctions in the blood brain barrier (BBB) with artemisinin as a potential adjuvant in the treatment of metastatic disease [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-20-04.