Abstract 1679: Characterization and establishment of triple negative breast cancer patient derived xenograft derived from a Nigerian woman

Abstract

Abstract Extensive literature has demonstrated the use of fresh human breast tumour tissue surgically implanted in immunodeficient mice to establish patient-derived xenograft (PDX) as a therapeutic assessment tool. Unfortunately, there is a paucity of genomic research using PDX as a preclinical tool for breast cancer metastasis in Nigerian women. Previous studies of rodent models have concentrated on cell line xenograft of other tumours usually of Caucasian or African American counterpart. To overcome this limitation, Triple-negative breast cancer (TNBC) was derived from a consenting 32-year-old Nigerian woman who had neoadjuvant therapy and had undergone a mastectomy. Triple-negative breast cancer lacks expression of hormone receptors including human epidermal receptor (HER2-), estrogen receptor (ER-) and progesterone receptor (PR-) genes. TNBC xenograft was established by orthotopic surgical implantation of breast cancer tissue fragments of 2mm3 in size with cultrex in the cleared breast pads of immunosuppressed mice and a further two passages. The size of the implanted tumour was checked twice weekly. Haematology & eosin histology and immunohistochemistry analysis were used to structurally and functionally characterize the tumour xenograft and primary tumour respectively. Real-time quantitative polymerase chain reaction (RQ-PCR) was used to evaluate the genomic correlation between primary tumour and tumour xenograft. Target genes compared between the tumour xenograft and primary tumours included CXCL16; CLD10; CDC42EP3; CXCL16; EPSTI1; PALMD and ZAN. Reference genes RLP13A and GAPDH were selected as assays for endogenous controls. All tumour tissues were mechanically homogenized and lysed in guanidine isothiocyanate buffer from which RNA was extracted and converted to cDNA by random hexamer priming. RQ-PCR was performed using TaqMan chemistries. This was validated by DNA sequencing of the xenografts tumour and primary tumour using Nanopore DNA sequencing, and Ligation Sequencing ID2 chemistry. The DNA sequences were aligned with Meg Align Pro The xenografts appear to maintain characteristic human histopathology, tumour-marker production. None of the tumours showed hormone sensitivity. There was a local invasion of breast cancer in the bone. The pairwise alignment yielded significant percentage relativity. Citation Format: Uzoamaka Adaobi Okoli, Michael Tochukwu Okafor, Kenneth A. Agu, Samuel R. Ohayi, Emmanuel O. Nna, Chioli P. Chijioke, Iroka J. Udeniya. Characterization and establishment of triple negative breast cancer patient derived xenograft derived from a Nigerian woman [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1679.