Decrease of Tumor-infiltrating Regulatory T Cells using Pentoxifylline:  An Ex Vivo Analysis in Triple-negative Breast Cancer Mouse Model

Mohammad Hossein Kazemi; Mahdieh  Shokrollahi Barough; Alireza Ghanavatinejad; Zahra  Momeni-Varposhti; Samaneh Khorrami; Behnam Sadeghi; Reza Falak

doi:10.18502/ijaai.v21i2.9224

Mohammad Hossein Kazemi Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
Mahdieh Shokrollahi Barough Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
Alireza Ghanavatinejad Department of Immunology, Pasteur Institute of Iran, Tehran, Iran
Zahra Momeni-Varposhti Hematopoietic Stem Cell Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
Samaneh Khorrami Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
Behnam Sadeghi Department of ATMP, Breast Cancer Research Center, Motamed Cancer Institute, ACECR, Tehran, Iran
Reza Falak Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran

DOI: https://doi.org/10.18502/ijaai.v21i2.9224

Keywords: Breast neoplasms; Pentoxifylline; Regulatory T- lymphocytes; Tumor-infiltrating lymphocytes

Abstract

Triple-negative breast cancer (TNBC) is the most aggressive type of BC with the highest percentage of tumor-infiltrating lymphocytes (TILs). Hence, TIL therapy is considered a promising approach to target TNBC. Depletion of regulatory T cells (Tregs) in TILs can improve the antitumor function of TIL therapy. Pentoxifylline (PTXF) is a xanthine derivative that can modulate the nuclear factor kappa B (NF-κB) signaling and probably affect the Treg proportion in TILs. We aimed to evaluate the ex vivo effect of PTXF on the proportion of Treg cells in the TILs derived from a mouse model of TNBC.

The 4T1 cells were inoculated subcutaneously to BALB/c mice to induce TNBC. TILs were isolated from tumor tissue by enzymatic digestion and cultured alone or with 4T1 cells for 24, 48, and 72 h in the presence of interleukin (IL)-2 and different concentrations of PTXF. The toxicity of PTXF and its effects on Tregs proportion as well as cytokine production was evaluated using MTT assay, flow cytometry, and ELISA, respectively.

PTXF had no significant impact on the viability of TILs. Both 500 and 1000 mg/mL of PTXF decreased the proportion of Tregs in a dose-dependent manner. The level of interferon-g and tumor growth factor-b in TILs supernatant were increased and decreased, respectively.

Our data suggest that ex vivo treatment of TILs with pentoxifylline could decrease the proportion of Tregs in the conventional IL-2-mediated TIL expansion and change the cytokine balance of TILs in favor of antitumor immune response.