Abstract 1297: BZW2 a potential target to inhibit colorectal cancer growth and metastasis
Authors: Bajpai Prachi , Agarwal Sumit , Afaq Farrukh , Behring Michael , Kim Hyung-Gyoon , Chandrashekar Darshan Shimoga , Peter Shajan , Diffalha Sameer Al , Khushman Moh’d , Seeber Andreas , Varambally Sooryanarayana , Manne Upender 
Published: April 2023

Introduction: Colorectal cancer (CRC) is the third leading cause of cancer-associated deaths in United States. Despite advances in therapeutic modalities, the overall survival rate for metastatic CRC remains poor. Therefore, there is an urgent need to identify potential drug targets, which are associated with CRC progression and metastasis. One such target is Basic leucine zipper and W2 domains 2 (BZW2), also known as translation initiation regulator eIF5-mimic protein 1 (5MP1), a member of the basic-region leucine zipper (bZIP) superfamily of transcription factors. BZW2 is upregulated in some human cancers; however, its function in CRC malignancy is unknown. Thus, the role of BZW2 in CRC is studied.

Methods: To address BZW2 role in CRC progression and metastasis, (1) we compared the RNA expression of BZW2 in human CRCs with their matched normal tissues (controls), (2) assessed the protein expression of BZW2 in primary CRCs and in CRCs which metastasized to liver, (3) as CRC is a molecularly heterogeneous disease, we conducted in vitro experiments, in CRC cell lines with various molecular alterations [P53, KRAS, BRAF, EGFR, or microsatellite stable/microsatellite instable (MSS/MSI) status], such as colony and spheroid formation to evaluate role of BZW2 on cell proliferation, (4) RNA-seq experiments with BZW2 knockdown (shRNA) to identify its downstream targets, and (5) to evaluate BZW2 role in CRC progression and metastasis, using BZW2 knockdown cells in in vivo models of NOD/SCID/IL2γ-receptor null (NSG) mice to assess tumor growth and the extent of metastasis.

Results: Our results demonstrated that BZW2 is upregulated in CRC tissues, at RNA and protein levels, as compared to their matched controls. A higher expression was also noted in CRC liver metastatic lesions compared to matched controls. Immunohistochemical results, on invasive CRC tissues further confirmed the findings of high expression of BZW2 in human CRCs. Our in vitro results with BZW2 knockdown in CRC cells (HCT116, SW480, and HT29 cells) showed reduced colony and spheroid formation. RNA-seq results comparing the expression in BZW2 knockdown cells with their controls, demonstrated key genes were modulated upon BZW2 knockdown, including those for P4HA1 and the long non-coding RNAs (lncRNAs), MALAT1 and NEAT1. Our in vivo experiments with SW480 xenografts showed smaller tumors in BZW2 knockdown as compared to those of controls. Knockdown of BZW2 in HT-29 luciferase-tagged cells, reduced metastasis in NSG mice, potentiating the fact that decreasing BZW2 would affect metastasis.

Conclusions: The results provide an evidence that BZW2 functions as an oncogene in CRC, regardless of their status of P53, KRAS, BRAF, EGFR, and MSS/MSI. Therefore, BZW2 may be an effective target for blocking CRC progression, and development of small molecule inhibitors of BZW2 could serve as potential therapeutic agents for CRC.

Citation Format: Prachi Bajpai, Sumit Agarwal, Farrukh Afaq, Michael Behring, Hyung-Gyoon Kim, Darshan Shimoga Chandrashekar, Shajan Peter, Sameer Al Diffalha, Moh’d Khushman, Andreas Seeber, Sooryanarayana Varambally, Upender Manne. BZW2 a potential target to inhibit colorectal cancer growth and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1297.