The Preclinical Activities of PTC596, a Novel Tubulin Binding Agent That Down-Regulates BMI1, Alone and in Combination with Bortezomib in Multiple Myeloma

作者：Yurie Nagai, Naoya Mimura, Ola Rizq, Yusuke Isshiki, Motohiko Oshima, Mohamed Rizk, Atsunori Saraya, Shuhei Koide, Yaeko Nakajima‐Takagi, Makiko Miyota, Nagisa Oshima‐Hasegawa, Shokichi Tsukamoto, Shio Mitsukawa, Yusuke Takeda, Chikako Ohwada, Masahiro Takeuchi, Tohru Iseki, Chiaki Nakaseko, Josephine Sheedy, Marla Weetall, Atsushi Iwama, Emiko Sakaida · 发表于：Blood · 年份：2019 · DOI：10.1182/blood-2019-122350 · 被引用次数：2 · 研究领域：Multiple Myeloma Research and Treatments、Ubiquitin and proteasome pathways、Microtubule and mitosis dynamics

Introduction: A novel tubulin binding agent PTC596, which is currently in clinical trials for solid tumors, was originally identified by its ability to kill cancer stem cells and to reduce BMI1 activity. PTC596 treatment results in hyperphosphorylation of the BMI1 protein and loss of BMI1 function as demonstrated by a reduction in H2A ubiquitination levels in a range of solid tumor lines. Subsequent studies have shown that the down-regulation of BMI1 protein is due to a G2/M arrest. In this study, we aimed to investigate the in-vitro and in-vivo anti-tumor activities of PTC596 and the combination with bortezomib in multiple myeloma (MM). Methods: For in-vitro evaluation, MTS and BrdU ELISA assays were performed using human MM cell lines. Approved by the Institutional Review Committee at Chiba University, primary myeloma cells and bone marrow stromal cells (BMSCs) were collected from the bone marrow of MM patients with informed consent. For in-vivo evaluation, the MM.1S subcutaneous xenograft model in NOG mice was used. To understand the mechanisms of action and target genes of the treatments, flow cytometry (FCM), western blotting, RNA-seq, and ChIP-seq were performed. Results: PTC596 induced significant cytotoxicity in all MM cell lines tested, including bortezomib-resistant OPM-2/BTZ and KMS-11/BTZ cells (CC50: 24-98 nM). PTC596 also suppressed cell proliferation when these cell lines were co-cultured with BMSCs. As expected, PTC596 reduced the levels of BMI1 protein and uH...