TY - JOUR
T1 - Targeted PARP Inhibition Combined with FGFR1 Blockade is Synthetically Lethal to Malignant Cells in Patients with Pancreatic Cancer
AU - Lai, Shiue Wei
AU - Bamodu, Oluwaseun Adebayo
AU - Chen, Jia Hong
AU - Wu, Alexander Th
AU - Lee, Wei Hwa
AU - Chao, Tsu Yi
AU - Yeh, Chi Tai
PY - 2020/4/8
Y1 - 2020/4/8
N2 - The role and therapeutic promise of poly-ADP ribose polymerase (PARP) inhibitors in anticancer chemotherapy are increasingly being explored, particularly in adjuvant or maintenance therapy, considering their low efficacy as monotherapy agents and their potentiating effects on concurrently administered contemporary chemotherapeutics. Against the background of increasing acquired resistance to FGFR1 inhibitors and our previous work, which partially demonstrated the caspase-3/PARP-mediated antitumor and antimetastatic efficacy of PD173074, a selective FGFR1 inhibitor, against ALDH-high/FGFR1-rich pancreatic ductal adenocarcinoma (PDAC) cells, we investigated the probable synthetic lethality and therapeutic efficacy of targeted PARP inhibition combined with FGFR1 blockade in patients with PDAC. Using bioinformatics-based analyses of gene expression profiles, co-occurrence and mutual exclusivity, molecular docking, immunofluorescence staining, clonogenicity, Western blotting, cell viability or cytotoxicity screening, and tumorsphere formation assays, we demonstrated that FGFR1 and PARP co-occur, form a complex, and reduce survival in patients with PDAC. Furthermore, FGFR1 and PARP expression was upregulated in FGFR1 inhibitor (dasatinib)-resistant PDAC cell lines SU8686, MiaPaCa2, and PANC-1 compared with that in sensitive cell lines Panc0403, Panc0504, Panc1005, and SUIT-2. Compared with the limited effect of single-agent olaparib (PARP inhibitor) or PD173074 on PANC-1 and SUIT-2 cells, low-dose combination (olaparib + PD173074) treatment significantly, dose-dependently, and synergistically reduced cell viability, upregulated cleaved PARP, pro-caspase (CASP)-9, cleaved-CASP9, and cleaved-CASP3 protein expression, and downregulated Bcl-xL protein expression. Furthermore, combination treatment markedly suppressed the clonogenicity and tumorsphere formation efficiency of PDAC cells regardless of FGFR1 inhibitor-resistance status and enhanced RAD51 and γ-H2AX immunoreactivity. In vivo studies have shown that both early and late initiation of combination therapy markedly suppressed tumor xenograft growth and increase in weight, although the effect was more pronounced in the early initiation group. In conclusion, FGFR1 inhibitor-resistant PDAC cells exhibited sensitivity to PD173074 after olaparib-mediated loss of PARP signaling. The present FGFR1/PARP-mediated synthetic lethality proof-of-concept study provided preclinical evidence of the feasibility and therapeutic efficacy of combinatorial FGFR1/PARP1 inhibition in human PDAC cell lines.
AB - The role and therapeutic promise of poly-ADP ribose polymerase (PARP) inhibitors in anticancer chemotherapy are increasingly being explored, particularly in adjuvant or maintenance therapy, considering their low efficacy as monotherapy agents and their potentiating effects on concurrently administered contemporary chemotherapeutics. Against the background of increasing acquired resistance to FGFR1 inhibitors and our previous work, which partially demonstrated the caspase-3/PARP-mediated antitumor and antimetastatic efficacy of PD173074, a selective FGFR1 inhibitor, against ALDH-high/FGFR1-rich pancreatic ductal adenocarcinoma (PDAC) cells, we investigated the probable synthetic lethality and therapeutic efficacy of targeted PARP inhibition combined with FGFR1 blockade in patients with PDAC. Using bioinformatics-based analyses of gene expression profiles, co-occurrence and mutual exclusivity, molecular docking, immunofluorescence staining, clonogenicity, Western blotting, cell viability or cytotoxicity screening, and tumorsphere formation assays, we demonstrated that FGFR1 and PARP co-occur, form a complex, and reduce survival in patients with PDAC. Furthermore, FGFR1 and PARP expression was upregulated in FGFR1 inhibitor (dasatinib)-resistant PDAC cell lines SU8686, MiaPaCa2, and PANC-1 compared with that in sensitive cell lines Panc0403, Panc0504, Panc1005, and SUIT-2. Compared with the limited effect of single-agent olaparib (PARP inhibitor) or PD173074 on PANC-1 and SUIT-2 cells, low-dose combination (olaparib + PD173074) treatment significantly, dose-dependently, and synergistically reduced cell viability, upregulated cleaved PARP, pro-caspase (CASP)-9, cleaved-CASP9, and cleaved-CASP3 protein expression, and downregulated Bcl-xL protein expression. Furthermore, combination treatment markedly suppressed the clonogenicity and tumorsphere formation efficiency of PDAC cells regardless of FGFR1 inhibitor-resistance status and enhanced RAD51 and γ-H2AX immunoreactivity. In vivo studies have shown that both early and late initiation of combination therapy markedly suppressed tumor xenograft growth and increase in weight, although the effect was more pronounced in the early initiation group. In conclusion, FGFR1 inhibitor-resistant PDAC cells exhibited sensitivity to PD173074 after olaparib-mediated loss of PARP signaling. The present FGFR1/PARP-mediated synthetic lethality proof-of-concept study provided preclinical evidence of the feasibility and therapeutic efficacy of combinatorial FGFR1/PARP1 inhibition in human PDAC cell lines.
KW - dasatinib
KW - FGFR1
KW - FGFR1 inhibitor-resistance
KW - FGFR1/PARP signaling
KW - olaparib
KW - pancreatic cancer
KW - PARP
KW - PD173074
KW - PDAC
KW - selective inhibitor
UR - http://www.scopus.com/inward/record.url?scp=85083216825&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85083216825&partnerID=8YFLogxK
U2 - 10.3390/cells9040911
DO - 10.3390/cells9040911
M3 - Article
C2 - 32276472
AN - SCOPUS:85083216825
SN - 2073-4409
VL - 9
JO - Cells
JF - Cells
IS - 4
M1 - 414
ER -