CRISPRi screens to identify combination therapies for the improved treatment of ovarian cancer

• Main Author: Handly, Erika Daphne.
• Other Authors: Michael Yaffe.
• Format: Others
• Language: English
• Published: Massachusetts Institute of Technology 2021
• Subjects: Biological Engineering.
• Online Access: https://hdl.handle.net/1721.1/130803

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biological Engineering, February, 2021 === Cataloged from the official PDF version of thesis. "February 2021." === Includes bibliographical references (pages 153-168). === Ovarian cancer is the fifth leading cause of cancer death for women in the United States, with only modest improvements in patient survival in the past few decades. Standard-of-care consists of surgical debulking followed by a combination of platinum and taxane agents, but relapse and resistance frequently occur. To identify genes that confer sensitivity or resistance in tumor cells treated with platinum chemotherapeutics, I performed genome-wide screens combining cisplatin or oxaliplatin with CRISPRi pooled gene knockdowns. Screens were analyzed at 9-days to mimic patient care, and at 48-hours to isolate the short-term DNA damage response. Genes whose knockdown caused sensitivity to the platinum chemotherapeutics were identified through a multi-objective optimization approach to account for knockdown efficiencies and variances in sequencing depth. === To filter the noise in the genome-wide screen and more confidently identify 'hits,' a smaller pooled CRISPRi screen of four hundred targets was designed, and a few 'hits' were validated. Interestingly, knockdown of FAAP24, a component of the FA core complex, was found to sensitize multiple ovarian cancer cells to platinum compounds, and thus may be a promising candidate for a combination treatment with oxaliplatin and cisplatin. Chapter 5 details an implementation of a combination therapy with cisplatin using peptide nanoparticles. Peptide nanoparticles are a promising therapeutic for the delivery of siRNA and allow for targeting of specific proteins that are difficult to inhibit with small molecular inhibitors; specifically, nanoplexes allowed for the targeting of the REV3 protein, the catalytic component of the translesion synthesis polymerase. === Interfering with REV3 expression through siRNA has a synergistic effect with cisplatin treatment in both human and mouse models of lung cancer, indicating that REV3 is an excellent target to combine with cisplatin therapies. This REV3 knock-down sensitivity was also extended to human ovarian cancer cell lines, indicating the potential of the combination treatment for both lung and ovarian cancers. === by Erika Daphne Handly. === Ph. D. === Ph.D. Massachusetts Institute of Technology, Department of Biological Engineering