Determining Genes Involved in Recovery From Chemotherapy in 4T1, EMT6, and EO771 Breast Cancer Cells

Authors

• Akash Jagdeesh, Virginia Commonwealth UniversityFollow
• Joseph Landry Ph.D., Virginia Commonwealth University School of MedicineFollow

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Abstract

Breast cancer is one of the most common types of cancer, and often has poor prognosis. Traditional treatments for breast cancer include chemotherapy, which involves a chemical attack on all growing cells within the body. However, these treatments are not 100% effective, and patients might experience recurrence in their cancer months or years after achieving remission. Cancer cells can evade chemotherapy through five mechanisms: senescence, quiescence, cytoprotective autophagy, and apoptosis/necroptosis suppression. Prior studies have conducted CRISPR screens and experiments involving inhibition of epigenetic regulators, to alter the regulation of genes that can contribute to breast cancer chemotherapy resistance. This study aims to expand on the previous studies that have been conducted, to determine the chromatin regulators that are critical to a cancer’s recovery from chemotherapy and that are critical to resistance to chemotherapy in EMT6, 4T1, and EO771 breast cancer cells. Growth of the cancer cells in mice were measured using tumor volume measurements, using caliper measurements every two days to determine width and length of tumors. Tumor measurements were conducted every two days starting on day five after implantation, measuring width and length of the tumors on each side. Western Blots were conducted to confirm that Cas9 was expressed in a doxycycline-dependent manner. The Cas9-positive 4T1 cells successfully developed tumors and grew in the Balb/C mice over the course of the 17-day growth period, without a significant difference in tumor volume from tumors developed from the control 4T1 cells, indicating that the Cas9-positive 4T1 cells are an accurate model of breast cancer in the mice. Due to time constraints, CRISPR knockout experiments were unable to be conducted to determine the effects of knocking out chromatin regulator genes on the growth of tumors and the resistance to chemotherapy, and will be conducted in the future.

Publication Date

2026

Subject Major(s)

Biology

Keywords

Chemotherapy, Treatment Resistance, Breast Cancer, Epigenetics, Chromatin

Disciplines

Animals | Cancer Biology | Cell Biology | Molecular Genetics

Current Academic Year

Senior

Faculty Advisor/Mentor

Joseph Landry, Ph.D.

Rights

© The Author(s)