The Combination of Chidamide and LB100 Induces Ferroptosis in Cutaneous T-Cell Lymphoma By Inhibiting the Cholesterol Synthesis Pathway

Background：Cutaneous T-cell lymphoma (CTCL) is a type of T-cell non-Hodgkin's lymphoma that originates in the skin, accounting for 75%-80% of all primary cutaneous lymphomas, and presents with a diverse range of clinical manifestations. Its treatment includes the use of various chemotherapeutic drugs, such as selective histone deacetylase inhibitors. However, like most chemotherapeutic drugs, the current single-agent therapy for CTCL faces challenges with sustained treatment responses and suboptimal efficacy. Therefore, this study aims to explore new combination therapeutic regimens based on existing chemotherapeutic agents and to investigate their potential mechanisms of action.

Objective：Explore the effects and mechanisms of the combination of Chidamide with LB100 in cutaneous T-cell lymphoma.

Methods: The CTCL cell lines Hut78 and H9 were selected for culture, and treated with chidamide and LB100 respectively according to an increasing concentration gradient; based on the results of the single-drug treatments, the two cell lines were treated with a combination of the two drugs at different concentrations. Combining the results of the single-drug and combination treatments, the two cell lines were divided into a control group, a chidamide monotherapy group (1μM), an LB100 monotherapy group (2μM), and a combination group, with drug treatment administered for 48H. Changes in the biological behavior of CTCL cells in the combination group compared to the control and monotherapy groups were analyzed through CCK-8, colony formation assays, flow cytometry, Western blotting, and animal models. The unique mechanism of action of the combination treatment in killing CTCL cells was analyzed using eukaryotic transcriptome sequencing, Western blot, qRT-PCR, immunohistochemistry, cholesterol testing kits, and lipid peroxidation probes.

Results: In vitro and in vivo experiments showed that, compared to the control group and monotherapy groups, cell proliferation in the combination group was significantly inhibited. Flow cytometry revealed that the combination group had increased cell apoptosis and cell cycle arrest. Transcriptome sequencing, Western blotting, qRT-PCR, and immunohistochemistry detected significant downregulation of cholesterol synthesis-related genes in the combination group, along with decreased expression of GPX4, confirming that the combined drug treatment induced ferroptosis by inhibiting the pathway of cholesterol synthesis. Additionally, cholesterol content testing also found a decrease in cellular cholesterol levels in the combination group. The detection of intracellular lipid peroxide content discovered a marked increase in lipid peroxidation levels in the combination group cells.

Conclusion: Our results indicate that the combination of chidamide and LB100 can synergistically inhibit the proliferation and colony formation of cutaneous T-cell lymphoma cells, promote cell cycle changes and apoptosis; and may induce ferroptosis in CTCL cells by inhibiting the pathway of cholesterol synthesis. This discovery has the potential to provide new insights into treatment options for CTCL patients, thereby identifying new potential therapeutic choices.

No relevant conflicts of interest to declare.