SLC7A11 suppresses ferroptosis via arginine metabolism and promotes tumor immune escape in acute lymphoblastic leukemia Free

Acute lymphoblastic leukemia (ALL) is a hematologic malignancy characterized by high heterogeneity. Despite advancements in treatment strategies that have improved survival rates, the progression of ALL continues to present significant challenges in achieving long-term remission. The mechanisms underlying the development of ALL remain largely unclear. Ferroptosis, a recently identified form of programmed cell death, has been shown to influence the prognosis of ALL. In this study, we identified SLC7A11 as a critical gene that inhibits ferroptosis, enhances immune evasion, and promotes disease progression through its effects on arginine metabolism in ALL, positioning it as a promising novel therapeutic target for ALL treatment.

To evaluate the impact of SLC7A11 on the cellular functions of ALL, we established ALL cell lines with either silenced or overexpressed SLC7A11. Subsequent investigations using CCK8, MTS assays, transmission electron microscopy, flow cytometry, and western blot analysis revealed that SLC7A11 promotes cell proliferation, reduces mitochondrial damage and lipid peroxidation, and decreases sensitivity to doxorubicin, without affecting apoptosis or autophagy in ALL cells. To elucidate the downstream mechanisms of SLC7A11, we performed RNA sequencing and metabolomics analysis on SLC7A11-silenced ALL cells and their corresponding controls. Further analyses, including qRT-PCR, metabolic flux analysis, and dual luciferase reporter assays, collectively demonstrated that SLC7A11 enhances the transcription of ASS1 and promotes arginine synthesis.

Moreover, to determine whether SLC7A11 influences the biological functions of ALL cells via ASS1 and its associated arginine metabolic pathway, we overexpressed ASS1 in SLC7A11-silenced ALL cells and conducted arginine intervention experiments. These studies revealed that, in vitro, the absence of arginine in the culture medium further inhibited the proliferation of SLC7A11-silenced ALL cells and exacerbated mitochondrial damage and lipid peroxidation, without affecting apoptosis. In vivo experiments indicated that arginine deprivation significantly reduced the infiltration of leukemic cells in the bone marrow and peripheral blood of mice with silenced SLC7A11; however, no extension in survival was observed in ALL mice fed an arginine-deficient diet.

At the clinical level, we utilized specimens from both primary and relapsed refractory ALL patients, as well as healthy volunteers, to conduct qRT-PCR, single-cell transcriptome sequencing, and mass spectrometry-based flow cytometry (CyTOF) assays. We integrated these data with RNA sequencing results from our institution and publicly available databases, demonstrating that SLC7A11 is overexpressed in ALL patients, potentially influencing NK cell infiltration and functionality. In arginine-depleted environments, silencing SLC7A11 in ALL cell lines resulted in a significant increase in the number of NK cells when co-cultured with peripheral blood mononuclear cells from healthy volunteers. Furthermore, SLC7A11 silencing enhanced the cytotoxic potential of NK-92MI cells against ALL cells, a capacity that was further amplified under arginine-deprived conditions.In conclusion, the upregulation of SLC7A11 increases arginine levels, modulates arginine metabolism, and suppresses ferroptosis, thereby promoting the proliferation of ALL cells. Concurrently, it reduces the number and activity of NK cells, facilitating immune evasion in ALL. Targeting SLC7A11 presents a promising novel therapeutic strategy for the treatment of ALL.