Small molecules that disrupt RAD54-BLM interaction hamper tumor proliferation in colon cancer chemoresistance models
Ekjot Kaur, … , Avinash Bajaj, Sagar Sengupta
Ekjot Kaur, … , Avinash Bajaj, Sagar Sengupta
Published February 29, 2024
Citation Information: J Clin Invest. 2024;134(8):e161941. https://doi.org/10.1172/JCI161941.
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Research Article Oncology

Small molecules that disrupt RAD54-BLM interaction hamper tumor proliferation in colon cancer chemoresistance models

Abstract

RAD54 and BLM helicase play pivotal roles during homologous recombination repair (HRR) to ensure genome maintenance. BLM amino acids (aa 181–212) interact with RAD54 and enhance its chromatin remodeling activity. Functionally, this interaction heightens HRR, leading to a decrease in residual DNA damage in colon cancer cells. This contributes to chemoresistance in colon cancer cells against cisplatin, camptothecin, and oxaliplatin, eventually promoting tumorigenesis in preclinical colon cancer mouse models. ChIP-Seq analysis and validation revealed increased BLM and RAD54 corecruitment on the MRP2 promoter in camptothecin-resistant colon cancer cells, leading to BLM-dependent enhancement of RAD54-mediated chromatin remodeling. We screened the Prestwick small-molecule library, with the intent to revert camptothecin- and oxaliplatin-induced chemoresistance by disrupting the RAD54-BLM interaction. Three FDA/European Medicines Agency–approved candidates were identified that could disrupt this interaction. These drugs bound to RAD54, altered its conformation, and abrogated RAD54-BLM–dependent chromatin remodeling on G5E4 and MRP2 arrays. Notably, the small molecules also reduced HRR efficiency in resistant lines, diminished anchorage-independent growth, and hampered the proliferation of tumors generated using camptothecin- and oxaliplatin-resistant colon cancer cells in both xenograft and syngeneic mouse models in BLM-dependent manner. Therefore, the 3 identified small molecules can serve as possible viable candidates for adjunct therapy in colon cancer treatment.

Authors

Ekjot Kaur, Ritu Agrawal, Rimpy Arun, Vinoth Madhavan, Vivek Srivastava, Dilip Kumar, Pragyan Parimita Rath, Nitin Kumar, Sreekanth Vedagopuram, Nishant Pandey, Swati Priya, Patrick Legembre, Samudrala Gourinath, Avinash Bajaj, Sagar Sengupta

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Figure 5

C3, C7, and C17 enhanced the effect of CPT and 1-OHP–mediated decrease in tumor volume in preclinical mice model.

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C3, C7, and C17 enhanced the effect of CPT and 1-OHP–mediated decrease i...
(A) C3, C7, and C17 decreased the levels of the HRR in HCT116 IC60 CPTR cells. HCT116 IC60 CPTR cells were transfected with the HR substrate for 72 hours, and the levels of HRR were determined in absence or presence of 100 nM C3, C7, and C17. Data are from 3 independent experiments. (B) C3, C7, and C17 decreased anchorage-independent cell growth of HCT116 IC60 CPTR cells. Soft agar assay was carried out in HCT116 IC60 CPTR cells by treating them with 100 nM C3, C7, and C17 along with 120 nM CPT. The number of soft agar colonies in each condition was counted. Data are from 3 independent experiments. (C–E) C3, C7, and C17 decreased tumor formation by camptothecin- and oxaliplatin-resistant cells in 2 xenograft models. HCT116 IC60 CPTR or HCT116 1-OHPR cells were injected into SCID mice (n = 5 in each group) or NSG mice (n = 3 in each group). The groups were made as indicated. The volume of the tumors was estimated for the indicated days. Data are shown as the mean ± SD. Data for C3 are shown in C, C7 in D, and C17 in E. (F and G) Treatment with both CPT and C17 decreased MRP2 transcript and protein levels. (F) RNA and (G) protein was isolated from tumors obtained at the end point of the xenograft experiment. RNA and the protein levels of MRP2 were determined by (F) RT-qPCR and (G) Western blotting with anti-MRP2 antibody. For each group, 3 tumor samples were analyzed. Data for F are from 3 mice. Data for G are from 1 mouse and are representative of the 3 mice analyzed. Data are shown as the mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, (A, B, and F) 1-way ANOVA; (C–E) 2-way ANOVA.