The Role of the Retinoblastoma Protein on Hypoxia-Inducible Factor Dependent Tumor Cell Transformation: Microarray Validation

Intratumoral hypoxia results in tumour cell adaptations mediated by the hypoxia inducible factor 1-α (HIF1-α) and its dimerization partner the aryl hydrocarbon receptor nuclear translocator (ARNT). This process is attenuated by the retinoblastoma protein (Rb) via its association with the thyroid hormone receptor/retinoblastoma interacting protein (TRIP230). This study’s aim was to examine the role of Rb on HIF1 tumour cell transformation. By interrogating the transcriptome of human MCF-7 and LNCaP cells using gene expression microarrays, we developed a list of 21 common HIF1 target genes further up-regulated following loss of Rb. Real-time PCR, immuno-blotting and immuno-cytochemistry were used to validate mRNA and protein levels of genes. Wound healing assays were used to measure cell migration following loss of Rb and hypoxia. Results show loss of Rb exacerbates the expression of HIF1 genes associated with neuroendocrine differentiation; however no change in cell migration was observed.