CRISPR/Cas9‐mediated mutagenesis to validate the synergy between PARP1 inhibition and chemotherapy in BRCA1‐mutated breast cancer cells

Abstract

For patients carrying BRCA1 mutations, at least one-third develop triple negative breast cancer (TNBC). Not only is TNBC difficult to treat due to the lack of molecular target receptors, but BRCA1 mutations (BRCA1m) also result in chemotherapeutic resistance, making disease recurrence more likely. Although BRCA1m are highly heterogeneous and therefore difficult to target, BRCA1 gene's synthetic lethal pair, PARP1, is conserved in BRCA1m cancer cells. Therefore, we hypothesize that targeting PARP1 might be a fruitful direction to sensitize BRCA1m cancer cells to chemotherapy. We used CRISPR/Cas9 technology to generate PARP1 deficiency in two TNBC cell lines, MDA-MB-231 (BRCA1 wild-type) and MDA-MB-436 (BRCA1m). We explored whether this PARP1 disruption (PARP1m) could significantly lower the chemotherapeutic dose necessary to achieve therapeutic efficacy in both a 2D and 3D tumor-on-a-chip model. With both BRCA1m and PARP1m, the TNBC cells were more sensitive to three representative chemotherapeutic breast cancer drugs, doxorubicin, gemcitabine and docetaxel, compared with the PARP1 wild-type counterpart in the 2D culture environment. However, PARP1m did not result in this synergy in the 3D tumor-on-a-chip model, suggesting that drug dosing in the tumor microenvironment may influence the synergy. Taken together, our results highlight a discrepancy in the efficacy of the combination of PARP1 inhibition and chemotherapy for TNBC treatment, which should be clarified to justify further clinical testing. K E Y W O R D S BRCA1, CRISPR/Cas9, PARP1, precision medicine, synthetic lethality, triple negative breast cancer Breast cancer is the leading cause of death in women worldwide. 1Around 12-17% of breast cancer patients have triple negative breast cancer (TNBC), 2 an aggressive, heterogeneous subtype characterized by the lack of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor Type 2 (HER2) expression.

Modeling breast cancer by grafting patient tumor samples in the avian embryo: anin vivoplatform for therapy evaluation coupled to large scale molecular analyses

“…We next assessed whether administration of gemcitabine and carboplatin MTDs, alone or in combination, could impact on MDA-MB-436 tumor growth in the avian embryo. TNBC cell line was described to be sensitive to both SOCs in a range of in vitro and in vivo studies (Larsson et al, 2020; Mintz et al, 2020). Each SOC MTD was injected intravenously in randomized batches of avian embryos 24 hours after engraftment of MDA-MB-436 cells.…”

PARP1-Inhibition Sensitizes Cervical Cancer Cell Lines for Chemoradiation and Thermoradiation

“…Adding PARP1- i to IR + cDDP or IR + HT might even lead to synthetic lethality, a phenomenon in which the combination of therapies leads to a strong synergistic effect rather than merely an additive effect [ 57 , 58 ]. When cells are treated with HT, this reduces the efficacy of HR, making the cells more susceptible to PARP1-inhibition [ 57 , 59 ].…”

Calcium Carbonate Nanoparticles Stimulate Cancer Cell Reprogramming to Suppress Tumor Growth and Invasion in an Organ-on-a-chip System

“…Thus, this platform can be used to simulate critical factors of human microenvironments, such as interstitial uid ow. Other studies have used micro uidic devices to study MDA-MB-231 cells (44). However separate conditions are often implemented on separate devices.…”