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Title: Dissecting PTEN function in cancer
Author: Fedorova, Marina
ISNI:       0000 0004 7657 5273
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2017
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PTEN downregulates a number of essential biological processes such as cell proliferation, survival and growth. Alterations of PTEN levels can lead to cancer, and PTEN is indeed one of the most frequently disrupted tumour suppressor genes in human cancers. Thus, anti-cancer treatment strategies focusing on PTEN deficiency could prove very beneficial. As such, a wide range of therapeutic approaches targeting cancers with various PTEN genotypes is currently at preclinical and clinical stages. Complete loss of PTEN expression by cells is less tumourigenic, more treatable and can be targeted by "lethal sensitivity" (increased sensitivity of PTEN deficient cells to radiation, cytotoxic drugs or treatment with inhibitors of downstream proteins). At the same time, cells with partial PTEN loss can be a target for "pro-senescence therapy" (activation of irreversible cell cycle arrest). Herein, we explore PTEN requirements for lethal sensitivity (focusing on Skp2 and NLK inhibition). Towards this goal, we have created isogenic PTEN wild type, heterozygous and null cells using CRISPR/Cas9 technology and introduced wild type or various functionally impaired forms of PTEN into those lines using CRISPR/Cas9 knock-in and Sleeping Beauty transposon system. Synthetic lethal sensitivities to inhibition of Skp2, TTK and PARP or to curcumin treatment did not provide robust responses. Using chemical genetics, an analogue sensitive version of the kinase NLK was constructed and using this for genetic engineering of human cells enabled the validation of the synthetic lethality between NLK and PTEN to be established. These results provide valuable insights into the cancer biology of PTEN and the reagents and techniques developed within this study will enable greater characterisation of anti-cancer therapies based on the genetic status of PTEN.
Supervisor: Mann, David ; Vilar, Ramon ; Woscholski, Rudiger Sponsor: Engineering and Physical Sciences Research Council ; AstraZeneca
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral