Abstract 6220: KDM1A inhibition sensitizes glioblastoma cells to temozolomide therapy through DNA damage and apoptosis pathway modulation
Authors: Palacios Bridgitte E. , Venkata Prabhakar Pitta , Chen Yihong , Alejo Salvador , He Yi , Viswanadhapalli Suryavathi , Pratap Uday , Liu Junhao , Li Xiaonan , Suzuki Takayoshi , Zheng Siyuan , Brenner Andrew , Vadlamudi Ratna , Sareddy Gangadhara 
Published: September 2020

Abstract
Background: Glioblastoma (GBM) is the most common brain tumor. Despite advancements in multimodal treatment strategies, GBM patients exhibit a dismal prognosis with a median survival of 20 months and a 5-year survival rate post diagnosis of 13%. Standard of care consists of surgical resection, external beam radiation therapy, and adjuvant chemotherapy with temozolomide (TMZ). Despite heavy investment in therapy, GBM patients inevitably experience tumor progression and eventually succumb to their disease. Recently, we showed that lysine-specific histone demethylase 1A (KDM1A), an epigenetic modifier, is overexpressed in GBM. In this study, we tested the hypothesis that KDM1A is essential for DNA damage response (DDR) and inhibition of KDM1A sensitizes GBM to TMZ therapy.
Methods: KDM1A knockout (KDM1A-KO) cells were generated using the CRISPR/Cas9 system and knockdown cells were generated using KDM1A specific shRNA (KDM1A-KD). We studied the effect of KDM1A-KO, -KD, or pharmacological KDM1A inhibitors (NCD-38 and NCL-1) on TMZ sensitization using Cell Titer-Glo luminescent cell viability assay, and survival assays. Apoptosis was determined using Caspase 3/7 and TUNEL assays. Mechanistic studies were conducted using RNA-seq, RT-qPCR, and Western blot analysis. Furthermore, the in vivo efficacy of KDM1A inhibitor and TMZ therapy was studied using orthotopic models of GBM using both male and female mice.
Results: Cell viability and survival assays demonstrated that knockout/knockdown or inhibition of KDM1A sensitized patient derived glioma stem cells (GSCs) to TMZ treatment. Further, combination of NCD-38 or NCL-1 and TMZ significantly increased the apoptosis of GSCs. RNA-seq analysis revealed the modulation of DDR and apoptotic pathways following combination therapy. Pharmacokinetics (PK) and brain bioavailability studies showed that NCD-38 has favorable PK properties and exhibited a significant penetration through the blood brain barrier. Importantly, combination of NCD-38 and TMZ significantly reduced the in vivo tumor progression and improved the overall survival of both male and female mice compared to single drug treatment in GBM orthotopic models.
Conclusions: Our results provide evidence that KDM1A knockdown/inhibition sensitizes GBM to TMZ therapy via modulation of DDR and that the use of KDM1A inhibitor in conjunction with TMZ could serve as a novel therapy for GBM patients.
Citation Format: Bridgitte E. Palacios, Prabhakar Pitta Venkata, Yihong Chen, Salvador Alejo, Yi He, Suryavathi Viswanadhapalli, Uday Pratap, Junhao Liu, Xiaonan Li, Takayoshi Suzuki, Siyuan Zheng, Andrew Brenner, Ratna Vadlamudi, Gangadhara Sareddy. KDM1A inhibition sensitizes glioblastoma cells to temozolomide therapy through DNA damage and apoptosis pathway modulation [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 6220.