Iranian Journal of Basic Medical Sciences

Iranian Journal of Basic Medical Sciences

Effects of siRNA-mediated TIGIT silencing on NK cell cytotoxicity against triple-negative and luminal breast cancer cells

Articles in Press

Document Type : Original Article

Authors
Zahed Barati Rakati 1
Nader Bagheri 2
Fatemeh Ghezelbash 3
Hajar Yaghoubi 1
Mehdi Ghatreh Samani 4
Kourosh Ashrafi 4, 5
Abdolkarim Sheikhi 6, 7
1 Clinical Biochemistry Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
2 Cancer Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran
3 Medical Plants Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
4 Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
5 Department of Molecular Medicine, School of Advanced Technologies, Shahrekord University of Medical Sciences, Shahrekord, Iran
6 Department of Immunology, School of Medicine, Dezful University of Medical Sciences, Dezful, Iran
7 Department of Biomedical & Molecular Sciences, Queen’s University, Kingston, ON K7L 3N6, Canada
10.22038/ijbms.2026.96441.20786
Abstract
Objective(s): TIGIT is an inhibitory immune checkpoint receptor expressed on NK and T cells. TIGIT interaction with CD155/CD112 suppresses anti-tumor immunity. We investigated whether siRNA-mediated TIGIT silencing in primary human NK cells enhances cytotoxicity against triple-negative (MDA-MB-231) and luminal (MCF-7) breast cancer cells.
Materials and Methods: NK cells were isolated from three treatment-naïve breast cancer patients and three healthy donors. For cytotoxicity assays, NK cells from the best‑expanding donor per group were selected; results are exploratory estimates. Cells were transfected with TIGIT‑specific or scrambled siRNA. TIGIT expression was assessed by qRT‑PCR, and cytotoxicity was measured using an AlamarBlue assay at an E:T ratio of 5:1.
Results: Baseline TIGIT expression was 1.5‑fold higher in patient‑derived NK cells (P=0.027). TIGIT silencing increased cytotoxicity against MDA‑MB‑231 cells by 9 percentage points in healthy donor NK cells (from 41% to 50%) and by 7 percentage points in patient NK cells (from 51% to 58%). Against MCF‑7 cells, increases were modest — only 3 to 3.5 percentage points (healthy: from 37.5% to 41%; patient: from 28% to 31%). Cytotoxicity values are descriptive estimates due to single‑donor assays. Across all conditions, patient NK cells were more active than healthy NK cells.
Conclusion: TIGIT silencing in primary human NK cells was associated with increased cytotoxicity against MDA‑MB‑231 cells but not against MCF‑7 cells. These preliminary findings support further investigation of TIGIT‑targeted NK cell therapy for triple‑negative breast cancer.
Keywords
Cell Line
Immune checkpoint Inhibitors
Immunotherapy
Killer cells
MCF-7 cells
Natural
RNA
Small Interfering
TIGIT protein
Triple negative
breast neoplasms
Tumor
Subjects
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Iranian Journal of Basic Medical Sciences

Articles in Press, Accepted Manuscript
Available Online from 10 November 2026