Solid tumours initiate angiogenesis to support their growth by producing growth factors such as VEGF. Depriving the tumour of the excessive vessels that support its growth became the target for developing anti-angiogenic agents that could provide, in combination with chemotherapy, improved anti-cancer treatment. We have recently reviewed the literature in this area (Anti-angiogenesis in cancer therapy: Hercules and hydra).
Mutations of PI3KCA have been reported in 10–20% of colorectal cancer (CRC), about 80% of mutations are found in two hot spots in exon 9 and exon 20 (reviewed in Cathomas 2014, see Figure below).
We have chosen a model system in which to investigate regulators of angiogenesis secreted by colon cancer cells harbouring activating mutations of PI3K at each of these loci (Mutant PIK3CA promotes cell growth and invasion of human cancer cells). We used the DLD1 colon cancer cell line which contains the E545 mutation in the helical domain of exon 9 and the HCT116 cell line which has an H1047R alteration in exon 20 (kinase domain). Both both cell lines were genome edited in the lab of Bert Vogelstein generating cell lines harboring either the wild type (WT) or the mutated (MUT) allele. This system has the advantage that one can investigate the mutation of interest in an isogenic background.
Our approach is: