Sequential therapeutic targeting of ovarian Cancer harboring dysfunctional BRCA1

Abstract

BackgroundPoly (ADP-ribose) polymerase inhibitors (PARPi) have become the first targeted therapies available in the treatment of patients with high-grade serous ovarian cancer (HGSOC). We recently described a significant reduction in PARP1 protein levels in vitro and in vivo in patients treated with standard carboplatinum-paclitaxel chemotherapy, raising the question whether the sequence of treatment used today with chemotherapy followed by PARPi is optimal. In this study, we aim to evaluate if the sequence of PARPi followed by chemotherapy could be more beneficial.MethodsBRCA1-mutated (UWB1.287, SNU-251), epigenetically-silenced (OVCAR8), and wild-type (SKOV3, A2780PAR & A2780CR) ovarian cancer cell lines were exposed to clinically relevant doses of PARPi followed by different doses of standard chemotherapy and compared to the inverse treatment. The therapeutic efficacy was assessed using colony formation assays. Flow cytometry was used to evaluate cell apoptosis rate and the changes in cell cycle. Finally, apoptotic and cell cycle protein expression was immunodetected using western blot.ResultsExposure to PARPi prior to standard chemotherapy sensitized BRCA1-mutated or epigenetically-silenced BRCA1 cell lines to lower doses of chemotherapy. Similar results were observed in BRCA1 wild-type and cell lines in which BRCA1 functionality was restored. Moreover, this treatment increased the apoptotic rate in these cell lines.ConclusionPre-treatment with PARPi followed by standard chemotherapy in vitro is more efficient in growth inhibition and induction of apoptosis compared to the administration of standard chemotherapy followed by PARPi.Electronic supplementary materialThe online version of this article (10.1186/s12885-018-5250-4) contains supplementary material, which is available to authorized users.

Genetically Defined, Syngeneic Organoid Platform for Developing Combination Therapies for Ovarian Cancer

“…As expected, Tp53 -/-;Brca1 -/-;Myc OE cells showed increased sensitivity to PARP-Is ( Fig. 2B), although differential sensitivity varied for individual PARP-Is and was less than seen in conventional ovarian cancer cell lines (41). Brca1-deleted cells showed slightly increased sensitivity to carboplatin, although there was substantial overlap with the other mutants.…”

Genetically Defined, Syngeneic Organoid Platform for Developing Combination Therapies for Ovarian Cancer

“…Likewise, the increased sensitivity of Tp53 -/-;Pten -/-;Nf1 -/cells to ATR inhibition comports with the previously reported role for nuclear PTEN in HR (Bassi et al, 2013;Shen et al, 2007). The reasons for the genotype-dependent differences in sensitivity to paclitaxel (for Tp53 -/-;Pten -/-;Nf1 -/cells) and to chloroquine (for Tp53 -/-;Pten -/-;Nf1 -/->Tp53 -/-;Ccne1 OE ;Akt2 OE ;Kras) are less clear.…”

“…Each agent was added at various doses, and cell viability was assessed 5 days later. As expected, Tp53 -/-;Brca1 -/-;Myc OE cells showed increased sensitivity to PARP-Is ( Figure 5B), although differential sensitivity varied for individual PARP-Is and was less than with conventional ovarian cancer cell lines (Baloch et al, 2019). Brca1-deleted cells showed slightly increased sensitivity to Carboplatin, although there was substantial overlap with the other mutants.…”

PARP Inhibition Increases the Reliance on ATR/CHK1 Checkpoint Signaling Leading to Synthetic Lethality—An Alternative Treatment Strategy for Epithelial Ovarian Cancer Cells Independent from HR Effectiveness

“…Cediranib suppresses pro-survival and anti-apoptotic signaling, thereby enhancing the efficacy of olaparib against BRCA WT EOC cells [ 34 ]. Despite the contribution of olaparib to modern ovarian cancer therapy, the response rate in women is not satisfactory [ 35 ]. Identifying novel and effective treatments is extremely important.…”