Kinome-wide CRISPR-Cas9 screen to identify kinases involved in Taxol resistance in breast cancer

Breast cancer is the most frequently diagnosed cancer in women, accounting for over 25% of cancer diagnoses and 13% of cancer-related deaths in Canadian women. There are many types of therapies for treatment or management of breast cancer, with chemotherapy being one of the most widely used. Taxol (paclitaxel) is one of the most extensively used chemotherapeutic agents for treating cancers of the breast and numerous other sites. Taxol stabilizes microtubules during mitosis, causing the cell cycle to arrest until eventually the cell undergoes apoptosis. Although Taxol has had significant benefits in many patients, response rates range from only 25-69%, and over half of Taxol-treated patients eventually acquire resistance to the drug. Drug resistance remains one of the greatest barriers to effective cancer treatment, yet little has been discerned regarding resistance to Taxol, despite its widespread clinical use. Kinases are known to be heavily involved in cancer development and progression, and several kinases have been linked to resistance of Taxol and other chemotherapeutic agents. However, a systematic screen for kinases regulating Taxol resistance is lacking. Thus, in this study, a set of kinome-wide screens was conducted to interrogate the involvement of kinases in the Taxol response. Positive-selection and negative-selection CRISPR-Cas9 screens were conducted, whereby a pooled library of 5070 sgRNAs targeted 507 kinase-encoding genes in MCF-7 breast cancer cells that were Taxol-sensitive (WT) or Taxol-resistant (TxR) which were then treated with Taxol. Next generation sequencing (NGS) was performed on cells that survived Taxol treatment, allowing identification and quantitation of sgRNAs. STK38, Blk, FASTK and Nek3 stand out as potentially critical kinases for Taxol-induced apoptosis to occur. Furthermore, kinases CDKL1 and FRK may have a role in Taxol resistance. Further validation of these candidate kinases will provide novel pre-clinical data about potential predictive biomarkers or therapeutic targets for breast cancer patients in the future.

AN INVESTIGATION ON ROUTINE FOLLOW-UP CARE FOR HEAD AND NECK CANCER

BACKGROUND: Follow-up care aims to provide surveillance with early detection of recurring cancers and to address treatment complications and other health issues in survivorship. It is assumed that follow-up care fulfills these aims, however little evidence supports routine surveillance detecting curable disease early enough to improve survival. Cancer survivors are a diverse patient population, suggesting that a single follow-up regimen may not meet all patients’ follow-up needs. Little is known about what effective follow-up care should include for head and neck cancer patients in a Canadian setting. Identification of subgroups of patients with specific needs and current practices would allow for hypotheses to be generated for enhancing follow-up care. OBJECTIVES: 1a) To describe the follow-up needs and preferences of head and neck cancer patients, 1b) to identify which patient characteristics predict needs and preferences, 1c) to evaluate how needs and preferences change over time, 2a) to describe follow-up care practices by physician visits and imaging tests, and 2b) to identify factors associated to the delivered follow-up care. METHODS: 1) 175 patients who completed treatment between 2012 and 2013 in Kingston and London, Ontario were recruited to participate in a prospective survey study on patients’ needs and preferences in follow-up care. Bivariate and multivariate analyses were employed to describe patient survey responses and to identify patient characteristics that predicted needs and preferences. 2) A retrospective cohort study of 3975 patients on routine follow-up from 2007 to 2015 was carried out using data linkages across registry and administrative databases to describe follow-up practices in Ontario by visits and tests. Multivariate regression analyses assessed factors related to follow-up care. RESULTS: 1) Patients’ needs and preferences were wide-ranging with several characteristics predicting needs and preferences (ORECOG=2.69 and ORAnxiety=1.13). Needs and preferences declined as patients transitioned into their second year of follow-up (p<0.05). 2) Wide variation in practices was found, with marked differences compared to existing consensus guidelines. Multiple factors were associated with follow-up practices (RRTumor site=0.73 and RRLHIN=1.47). CONCLUSIONS: Patient characteristics can be used to personalize care and guidelines are not informing practice. Future research should evaluate individualized approaches to follow-up care.