Natural killer (NK) cells are the first native invaders against malignancy. NK cells activity is regulated by an array of activating and inhibitory receptors present on their surface. UL-16 binding proteins (ULBP 1-6) are ligands expressed by malignant cells to be detected by NKG2D activating receptor and consequent eradication of transformed cells by NK cells. Breast cancer (BC) patients experience a shedding of ULBP2 ligand in an attempt to evade immune surveillance process exhibited by NK cells. Yet, the mechanism behind the de-regulation of ULBP2 in BC is still to be explored. Crosstalk between different classes of non coding RNAs (ncRNAs) is the current research hotspot. Our research group has recently highlighted a harmonic interplay between several microRNAs and long ncRNAs regulating the immunogenic profile of BC cells. However, the ncRNAs circuit regulating ULBP2 in BC has yet to be identified. Therefore, the aim of this study is to identify the ncRNA circuit regulating ULBP2 in BC cells.
BC patients were recruited (n=30). Bioinformatic analysis was performed. MDA-B-231 cells are cultured and transfected by different oligonucleotides using lipofection technique. RNA was extracted using biozol, reverse transcribed and amplified and quantified using q-RT-PCR. BC cells transfected with ncRNAs are functionally analyzed using MTT, colony forming and migration assays. Statistical analysis was done using GraphPad 9.0.
In silico analysis revealed a potential targeting capacity of miR-17-5p to STAT3, H19. Moreover, miR-17-5p and H19 were found to target ULBP2. Screening showed an under-expression of miR-17-5p in BC tissues and an up-regulation of STAT3 and H19. miR-17-5p mimics and H19 siRNAs repressed BC hallmarks. Ectopic expression of miR-17-5p mimics resulted in a repression of STAT3, H19 and induction of ULBP2 levels. Knocking down of STAT3 repressed H19 levels and induced ULBP2. Consquently, H19 siRNAs induced ULBP2 levels.
This study showed miR-17-5p/STAT3/H19 as a vital regulatory axis for ULBP2 in BC cells. The current evidence also supports the nomination of miR-17-5p as a potential therapeutic option for BC patients counteracting the immune intolerance phenomena exhibited by BC cells.
German University in Cairo.
Has not received any funding.
All authors have declared no conflicts of interest.