High-throughput screening identifies potential drugs for low-grade serous ovarian cancer

By Dr. Chinta SidharthanReviewed by Lexie CornerSep 26 2024

Low-grade serous ovarian carcinoma (LGSOC) is a rare subtype of epithelial ovarian tumor, making it challenging to characterize adequately. As a result, current treatment approaches are often based on the more common high-grade serous ovarian carcinoma (HGSOC).

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LGSOC’s tendency for late diagnosis and resistance to chemotherapy contribute to low survival rates.

In a recent study published in Scientific Data, an Australian research team performed a large-scale high-throughput drug screening on LGSOC patient-derived cells and normal cells. This study aimed to uncover molecular genetic characteristics unique to LGSOC, with the goal of advancing research toward more effective therapies.

Background

LGSOC accounts for 5 % to 8 % of epithelial ovarian tumors and is generally diagnosed in younger women. It shows significant resistance to chemotherapy, especially in recurrent cases, making primary cytoreductive surgery, followed by chemotherapy and hormone therapy, the preferred treatment approach. This is due to the increased expression of estrogen and progesterone receptors in LGSOC.

At the molecular level, mutations in the Kirsten rat sarcoma (KRAS) oncogene, neuroblastoma rat sarcoma (NRAS) oncogene, and B-Raf (BRAF) proto-oncogene suggest that the mitogen-activated protein kinase (MAPK) pathway is involved in LGSOC.

However, many LGSOC cases show no known mutations and treatments targeting the MAPK pathway have had limited success. This underscores the need for a deeper understanding of the genetic basis of LGSOC and the development of more effective therapeutic strategies.

About the study

In this study, researchers utilized high-throughput drug screening to identify potential new treatments for LGSOC. They tested over 3,400 candidate compounds on 12 LGSOC cell lines and one normal ovarian epithelial cell line.

Live cell imaging was used to monitor cell growth kinetics, with cells seeded at varying densities and imaged every 8 hours over 168 hours to assess confluence. Plates with the lowest seeding density that reached approximately 80 % confluence within 72 hours were selected for subsequent screening.

Three compound libraries were used: one with over 5,500 FDA-approved drugs, and two others with 430 kinase inhibitors and 684 epigenetic modulators. The entire library of FDA-approved drugs was initially screened against four cell lines. Subsequently, 2,322 compounds were selected for screening against the remaining cell lines.

Robotic systems were employed for all steps in the drug dosing and handling process, and a high-content imager was used to capture cell images. In both the primary and secondary screenings, cells were seeded into 384-well plates and treated with the drug compounds.

After 72 hours, cell viability was assessed through imaging, and the compounds were categorized into four groups based on their impact on cell viability, ranging from high to low.

Drugs causing significant cell death were classified as high-confidence hits, while those with moderate effects were considered for broader therapeutic applications. The cytotoxic effects of these compounds were further validated in additional LGSOC cell lines.

Major findings

The study identified 60 high-confidence hit compounds and 19 moderate-confidence hit compounds that exhibited cytotoxicity, specifically against cancer cells, at doses as low as 0.1 micromolar.

The study's quality control was robust, with multiple replicates of positive and negative controls ensuring the reliability of the findings. Positive controls included Carboplatin, Cisplatin, Doxorubicin, Mitomycin C, Paclitaxel, and Staurosporine. Staurosporine showed the highest toxicity across all cell lines, while Carboplatin showed the least.

The researchers also identified molecular targets that were believed to play a key role in LGSOC. These included the mitogen-activated protein kinase kinase (MAP2K)/ mitogen-activated protein kinase kinase kinase (MAP3K)/ extracellular signal-regulated kinase (MAPK) or the MEK/RAF/ERK pathway.

The other molecular pathway found to play a key role in LGSOC was the mammalian target of rapamycin (mTOR)/ phosphoinositide 3 kinase (PI3K)/ protein kinase B (AKT) pathway.

Conclusions

This study highlights the value of comprehensive high-throughput drug screening in uncovering key molecular drivers and identifying potential therapeutic options for rare cancers like LGSOC. The use of normal ovarian cell lines helped reduce off-target effects, supporting a more personalized treatment strategy for LGSOC

Journal reference

Pishas, KI., Cowley, KJ., Llaurado-Fernandez, M., Kim, H., Luu, J., Vary, R., Bowden, NA., Campbell, IG., Carey, MS., Simpson, KJ., Cheasley, D. (2024). High-throughput drug screening identifies novel therapeutics for Low Grade Serous Ovarian Carcinoma. Scientific Data. DOI:10.1038/s4159702403869x, https://www.nature.com/articles/s41597-024-03869-x