Hongzoo Park1, Yunlim Kim2,3,4, Jee-Won Sul3,4, In Gab Jeong2, Hye-Jin Yi3,4, Jae Beom Ahn4, Jong Soon Kang5, Jieun Yun5, Jung Jin Hwang3,4, Choung-Soo Kim2,3,4. 1. Department of Urology, Kangwon National University Hospital, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, South Korea. 2. Department of Urology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea. 3. Institute for Innovative Cancer Research, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea. 4. Asan Institute for Life Sciences, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea. 5. Bioevaluation Center, Korea Research Institute of Bioscience and Biotechnology, Ochang, Cheongwon, South Korea.
Abstract
BACKGROUND: PTEN deletion, mutation or reduced expression occurs in 63% of metastatic prostate tumors, resulting in the activation of PI3K and its downstream targets, AKT and mTOR. Inhibition of the PI3K pathway results in upregulation of the MAPK pathway. Therefore, co-administration of inhibitors of both pathways, GSK2126458 as a dual PI3K/mTOR inhibitor, and AZD6244 as a MEK inhibitor, is able to overcome resistance and increase anti-tumor efficacy. METHODS: PC3, DU145, LNCaP, and CRPC patient-derived cells were used to assess apoptosis upon exposure to the drug combination. The human DU145 and PC3 tumor xenograft mouse model was employed to evaluate in vivo efficacy. CellTiter Glo® luminescent assay, annexin V-FITC apoptosis detection, cell cycle analysis, Western blotting and immunohistochemistry were conducted. Statistical evaluation of the results was performed by one-way ANOVA. RESULTS: The combination of GSK2126458 and AZD6244 inhibited the growth of DU145 and PC3 prostate cancer cells in vitro and in vivo. GSK2126458 decreased phospho-AKT while increasing phospho-ERK and AZD6244 decreased phospho-ERK efficiently while increasing phospho-AKT. The combination of GSK2126458 and AZD6244 decreased both phospho-AKT and phospho-ERK effectively in vitro and in vivo. The combination treatment synergistically induced annexin V-positive cells, sub-G1 cells, and cleavage of caspase-9, caspase-3 and poly-ADP ribose polymerase (PARP) in DU145 cells in vitro. Moreover, the combination decreased the level of Ki-67, and increased TUNEL-positive cells and cleaved caspase-3 in DU145 xenograft tumors implanted in mice. In addition, this combination treatment inhibited both the PI3K and MEK pathway primary in cultures from CRPC patients harboring PTEN loss, leading to synergistic anti-tumor effect. CONCLUSIONS: The combination of GSK2126458 and AZD6244 blocks both the RAS/RAF/MEK/ERK and PI3K/AKT/mTOR pathways simultaneously and is an effective strategy for the treatment of CRPCs.
BACKGROUND:PTEN deletion, mutation or reduced expression occurs in 63% of metastatic prostate tumors, resulting in the activation of PI3K and its downstream targets, AKT and mTOR. Inhibition of the PI3K pathway results in upregulation of the MAPK pathway. Therefore, co-administration of inhibitors of both pathways, GSK2126458 as a dual PI3K/mTOR inhibitor, and AZD6244 as a MEK inhibitor, is able to overcome resistance and increase anti-tumor efficacy. METHODS:PC3, DU145, LNCaP, and CRPC patient-derived cells were used to assess apoptosis upon exposure to the drug combination. The human DU145 and PC3tumor xenograft mouse model was employed to evaluate in vivo efficacy. CellTiter Glo® luminescent assay, annexin V-FITC apoptosis detection, cell cycle analysis, Western blotting and immunohistochemistry were conducted. Statistical evaluation of the results was performed by one-way ANOVA. RESULTS: The combination of GSK2126458 and AZD6244 inhibited the growth of DU145 and PC3prostate cancer cells in vitro and in vivo. GSK2126458 decreased phospho-AKT while increasing phospho-ERK and AZD6244 decreased phospho-ERK efficiently while increasing phospho-AKT. The combination of GSK2126458 and AZD6244 decreased both phospho-AKT and phospho-ERK effectively in vitro and in vivo. The combination treatment synergistically induced annexin V-positive cells, sub-G1 cells, and cleavage of caspase-9, caspase-3 and poly-ADP ribose polymerase (PARP) in DU145 cells in vitro. Moreover, the combination decreased the level of Ki-67, and increased TUNEL-positive cells and cleaved caspase-3 in DU145 xenograft tumors implanted in mice. In addition, this combination treatment inhibited both the PI3K and MEK pathway primary in cultures from CRPC patients harboring PTEN loss, leading to synergistic anti-tumor effect. CONCLUSIONS: The combination of GSK2126458 and AZD6244 blocks both the RAS/RAF/MEK/ERK and PI3K/AKT/mTOR pathways simultaneously and is an effective strategy for the treatment of CRPCs.
Authors: Soon Young Park; Sandeep Mittal; Jianwen Dong; Kangjin Jeong; Emmanuel Martinez-Ledesma; Yuji Piao; Sabbir Khan; Verlene Henry; Roel Gw Verhaak; Nazanin Majd; Veerakumar Balasubramaniyan; John F de Groot Journal: Am J Cancer Res Date: 2020-11-01 Impact factor: 6.166