Conventional frontline treatment for ovarian cancer consists of successive chemotherapy cycles of paclitaxel and platinum. Despite the initial favorable responses for most patients, chemotherapy resistance frequently leads to recurrent or refractory disease. New treatment strategies that circumvent or prevent mechanisms of resistance are needed to improve ovarian cancer therapy. We established in vitro paclitaxel-resistant ovarian cancer cell line and organoid models. Gene expression differences in resistant and sensitive lines were analyzed by RNA sequencing. We manipulated candidate genes associated with paclitaxel resistance using siRNA or small molecule inhibitors, and then screened the cells for paclitaxel sensitivity using cell viability assays. We used the Bliss independence model to evaluate the anti-proliferative synergy for drug combinations. ABCB1 expression was upregulated in paclitaxel-resistant TOV-21G (q < 1x10-300), OVCAR3 (q = 7.4x10-156) and novel ovarian tumor organoid (p = 2.4x10-4) models. Previous reports have shown some tyrosine kinase inhibitors can inhibit ABCB1 function. We tested a panel of tyrosine kinase inhibitors for the ability to sensitize resistant ABCB1-overexpressing ovarian cancer cell lines to paclitaxel. We observed synergy when we combined poziotinib or lapatinib with paclitaxel in resistant TOV-21G and OVCAR3 cells. Silencing ABCB1 expression in paclitaxel-resistant TOV-21G and OVCAR3 cells reduced paclitaxel IC50 by 20.7 and 6.2-fold, respectively. Furthermore, we demonstrated direct inhibition of paclitaxel-induced ABCB1 transporter activity by both lapatinib and poziotinib. In conclusion, lapatinib and poziotinib combined with paclitaxel synergizes to inhibit the proliferation of ABCB1-overexpressing ovarian cancer cells in vitro. The addition of FDA-approved lapatinib to second-line paclitaxel therapy is a promising strategy for patients with recurrent ovarian cancer.

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Published in PLOS ONE, v. 16, issue 8, 0254205.

© 2021 McCorkle et al.

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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Financial support of this work was provided by the National Institute of Health (www.nih.gov): P30 CA177558 (JMK) and T32 CA160003 (JWG). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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RNAseq data files are available from the GEO database (Accession GSE172016). All other relevant data are available from the additional files listed at the end of this record.

pone.0254205.s001.xlsx (776 kB)
S1 Table. Differentially expressed genes associated with paclitaxel resistance in ovarian cancer cell lines. https://doi.org/10.1371/journal.pone.0254205.s001

pone.0254205.s002.tif (137 kB)
S1 Fig. Drug synergy in OVCAR3 cells. https://doi.org/10.1371/journal.pone.0254205.s002

pone.0254205.s003.tif (618 kB)
S2 Fig. Real-time PCR analysis of siRNA efficacy in TOV-21G cells. https://doi.org/10.1371/journal.pone.0254205.s003

pone.0254205.s004.tif (699 kB)
S3 Fig. Real-time PCR analysis of siRNA efficacy in OVCAR3 cells. https://doi.org/10.1371/journal.pone.0254205.s004

pone.0254205.s005.tif (1234 kB)
S4 Fig. Time course real-time PCR analysis of siRNA efficacy in TOV-21G-control and -PacR cells. https://doi.org/10.1371/journal.pone.0254205.s005

pone.0254205.s006.tif (1238 kB)
S5 Fig. Time course real-time PCR analysis of siRNA efficacy in OVCAR3-control and -PacR cells. https://doi.org/10.1371/journal.pone.0254205.s006

pone.0254205.s007.tif (383 kB)
S6 Fig. Lapatinib sensitivity in control and paclitaxel-resistant TOV-21G and OVCAR3 cells. https://doi.org/10.1371/journal.pone.0254205.s007

pone.0254205.s008.tif (247 kB)
S7 Fig. ABCB1 expression in TOV-21G-control and–PacR cells following ErbB family gene silencing. https://doi.org/10.1371/journal.pone.0254205.s008

pone.0254205.s009.tif (712 kB)
S8 Fig. Read depth for RNA sequencing analysis of immortalized cell lines. https://doi.org/10.1371/journal.pone.0254205.s009