Investigation of the inhibition of FOXO1 as an important mechanism for oncogenesis in lung cancer induced by KRAS mutations

• Grant number: 15/08729-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): June 01, 2015
• Effective date (End): February 29, 2016
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal Investigator: Daniela Sanchez Basseres
• Grantee: Fernando Galassi Stocco Neto
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Lung cancer is the deadliest type of cancer. By analyzing genetic variations in lung neoplasms, we notice that point mutations in the proto-oncogene KRAS are the most frequent ones, being identified in nearly 33% of all cases of lung adenocarcinoma. Due to the notable causative effect of activating point-mutations of the KRAS gene, many studies have tried to directly inhibit the action of its product, having no success until now. Therefore, it is very important to study the role KRAS effector proteins play in oncogenic transformation, so that new strategies for therapeutic intervention can be identified. This work aims to increase our knowledge about KRAS targets. For that purpose, we will work with two main hypotheses: the first would be that KRAS down-regulates the expression of tumor suppressor gene FOXO1; the second would be that this regulation is important for transformation and development of a malignant phenotype. Both hypotheses are based on literature data about how FOXO1 down-regulation contributes to increase cell proliferation on non-small cell lung cancer (NSCLC, the most frequent type associated with KRAS mutations) cell lines, on the fact that KRAS could induce the inhibitory phosphorylation of FOXO1 by activating the PI3K/Akt pathway and also based on data generated in our laboratory showing a negative correlation between the expression of oncogenic KRAS and the expression of FOXO1 in lung cancer cells. This work has two main strategies: the first is to investigate the regulation of FOXO1 by KRAS; and the second is to investigate, in lung cancer cells transformed by KRAS, whether the inhibition of FOXO1 is capable of rescuing the loss of oncogenicity caused by inhibition of KRAS expression. For the second strategy we will evaluate how simultaneous inhibition of FOXO1 and KRAS compares to inhibition of KRAS alone when it comes to the impact on the malignant phenotype. For that purpose we will use colony formation assays in adherent substrate (analyzing cell viability) and colony formation in soft agar (analyzing malignant transformation). We expect that this work will contribute to a better understanding of how oncogenic KRAS promotes the malignant phenotype and also provide knowledge that could lead to new therapeutic strategies for lung cancer.