JF-305, a pancreatic cancer cell line is highly sensitive to the PARP inhibitor olaparib

Abstract

Poly(ADP-ribose) polymerase-1 (PARP-1) is a DNA nick sensor involved in the base excision repair (BER) pathway. Olaparib, a PARP inhibitor, has demonstrated antitumor activity in homologous recombination (HR)-deficient cancers. To extend this specific therapy to other types of carcinomas, a panel of 11 different cancer cells were screened in the present study. JF-305, a pancreatic cancer cell line of Chinese origin, demonstrated sensitivity to the PARP inhibitor 6(5H)-phenanthridinone. In the present study, 3 μM olaparib conferred a cell survival rate of 25% following four days of treatment. The colony formation efficiency was 83% at 10 nM, and dropped to 12% at 1 μM following seven days of treatment. Furthermore, olaparib induced cell cycle arrest in the S and G₂/M phases prior to the initiation of apoptosis. Although the incidence of double-strand breaks (DSBs) was increased in the olaparib-treated JF-305 cells, the RAD51 foci were well formed at the sites of γ-H2AX recruitment, indicating an activated HR mechanism. Furthermore, tumor growth was reduced by 49.8% following 22 days of consecutive administration of 10 mg/kg olaparib in the JF-305 xenograft mouse model. In summary, the JF-305 cell line was sensitive to olaparib and provided a prospective model for the preclinical assessment of PARP inhibitors in the therapy of pancreatic cancer.

Keywords: JF-305 cells; cell cycle; homologous recombination repair; olaparib; pancreatic cancer.

Figure 1

Compared with other cell types, JF-305 cells demonstrate relatively high sensitivity of their colony formation efficiency to the PARP inhibitor PHE. Rin5f, islet tumor cell; B16, skin melanoma cell; Acc-3, salivary gland adenoid cystic carcinoma cell; Patu8988, pancreatic cancer cell; Bel7402, hematoma cell; HNE2, nasopharyngeal carcinoma cell; HepG2, hepatocellular carcinoma cell; DU145, prostate cancer cell; SGC7901, gastric cancer cell; A549, lung adenocarcinoma cell; PHE, 6(5H)-phenanthridinone. Data are expressed as the mean ± standard deviation (n=3).

Figure 2

JF-305 cells are sensitive to olaparib. (A) Olaparib selectively inhibited the growth of the JF-305, MDA-MB-436 (BRCA-1 deficient) and Capan-1 (BRCA-2 deficient) cells, but not the T47D (BRCA-1 and BRCA-2 proficient) cells. (B) The colony formation efficiency of the JF-305 cells was inhibited by increasing concentrations of olaparib. Data are expressed as the mean ± standard deviation (n=3).

Figure 3

Olaparib induces the DNA damage, cell cycle arrest and cell death of JF-305 cells. (A) Co-immunostaining reveals DSBs and HRR represented by γ-H2AX and RAD51 foci formation in the JF-305 cells exposed to olaparib or a vehicle. (B) S and G₂/M cell cycle phases were arrested by increasing concentrations of olaparib and analyzed by flow cytometry. (C) DAPI-stained nuclei analysis of JF-305 cells incubated with olaparib and a vehicle. DSBs, double-strand breaks; HRR, homologous recombination repair.

Figure 4

Olaparib delayed the growth of the JF-305 tumors in vivo compared with the vehicle. RTV, relative tumor volume; ip, intraperitoneal injection; qd, once daily. Results are presented as the mean ± standard deviation (n=6).