Modulating retinoid-X-receptor alpha (RXRA) expression sensitizes chronic myeloid leukemia cells to imatinib in vitro and reduces disease burden in vivo

Bharathi M Rajamani; Raveen Stephen Stallon Illangeswaran; Esther Sathya Bama Benjamin; Balaji Balakrishnan; Daniel Zechariah Paul Jebanesan; Saswati Das; Aswin Anand Pai; Rakhi Thalayattu Vidhyadharan; Ajith Mohan; Sreeja Karathedath; Aby Abraham; Vikram Mathews; Shaji R Velayudhan; Poonkuzhali Balasubramanian

doi:10.3389/fphar.2023.1187066

Modulating retinoid-X-receptor alpha (RXRA) expression sensitizes chronic myeloid leukemia cells to imatinib in vitro and reduces disease burden in vivo

Front Pharmacol. 2023 May 31:14:1187066. doi: 10.3389/fphar.2023.1187066. eCollection 2023.

Authors

Bharathi M Rajamani^{1

2}, Raveen Stephen Stallon Illangeswaran^{1

2}, Esther Sathya Bama Benjamin^{1

3}, Balaji Balakrishnan^{1

4}, Daniel Zechariah Paul Jebanesan^{1

5}, Saswati Das^{1

2}, Aswin Anand Pai^{1

3}, Rakhi Thalayattu Vidhyadharan¹, Ajith Mohan¹, Sreeja Karathedath¹, Aby Abraham¹, Vikram Mathews¹, Shaji R Velayudhan^{1

6}, Poonkuzhali Balasubramanian¹

Affiliations

¹ Department of Haematology, Christian Medical College, Vellore, India.
² Department of Biotechnology, Thiruvalluvar University, Vellore, India.
³ Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, India.
⁴ Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, India.
⁵ Manipal Academy of Higher Education, Manipal, India.
⁶ Centre for Stem Cell Research (CSCR), A Unit of InStem Bengaluru, Christian Medical College Campus, Vellore, India.

Abstract

Introduction: The ligand-activated transcription factors, nuclear hormone receptors (NHRs), remain unexplored in hematological malignancies except for retinoic acid receptor alpha (RARA). Methods: Here we profiled the expression of various NHRs and their coregulators in Chronic myeloid leukemia (CML) cell lines and identified a significant differential expression pattern between inherently imatinib mesylate (IM)-sensitive and resistant cell lines. Results: Retinoid-X-receptor alpha (RXRA) was downregulated in CML cell lines inherently resistant to IM and in primary CML CD34⁺ cells. Pre-treatment with clinically relevant RXRA ligands improved sensitivity to IM in-vitro in both CML cell lines and primary CML cells. This combination effectively reduced the viability and colony-forming capacity of CML CD34⁺ cells in-vitro. In-vivo, this combination reduced leukemic burden and prolonged survival. Overexpression (OE) of RXRA inhibited proliferation and improved sensitivity to IM in-vitro. In-vivo, RXRA OE cells showed reduced engraftment of cells in the bone marrow, improved sensitivity to IM, and prolonged survival. Both RXRA OE and ligand treatment markedly reduced BCR::ABL1 downstream kinase activation, activating apoptotic cascades and improving sensitivity to IM. Importantly, RXRA OE also led to the disruption of the oxidative capacity of these cells. Conclusion: Combining IM with clinically available RXRA ligands could form an alternative treatment strategy in CML patients with suboptimal response to IM.

Keywords: RXRA; RXRA ligands; chronic myeloid leukemia (CML); imatinib; resistance.

Grants and funding

This study is supported by a Centre of Excellence grant from the Department of Biotechnology India: BT/COE/34/SP13432/2015 and the Indian Council of Medical Research Centre for Advanced Research grant 70/14/14-CAR to PB. This study is partly supported by CMC Fluid research grants: IRB No. 11169 & 12061 to PB and BR. SV and PB are supported by Wellcome DBT India Alliance (IA/S/17/1/503118 and IA/S/15/1/501842), respectively. BR, RI and DJ supported by ICMR SRF. SK and SD were supported by University Grants Commission, AP by DBT SRF, ESB by DST Inspire SRF, and RV by CSIR JRF.