As part of a research project funded by CHECT, Dr Sandy Hung from the Centre for Eye Research Australia talks through her team’s latest breakthrough in understanding the progression of Rb, paving the way for the development of new possible treatments
The RB1 gene, which is mutated in retinoblastoma, was the first ‘tumour suppressor gene’ (a gene that regulates a cell during cell division and replication) to be identified. Its mechanisms, which can lead to cancer, have been extensively studied in the past few decades.
However, it has been more challenging to understand the cellular and physiological aspects of retinoblastoma due to the difficulties in generating a good model that accurately recreates the disease progression. Often the cell lines developed from existing retinoblastoma tumours are the result of ‘endpoint transformation’, and may have acquired multiple mutations and chromosome abnormalities, and therefore may not be a good model for retinoblastoma initiation and progression.
Breakthroughs in technology now allow us to take a patient’s skin cells and generate stem cells, which can be further differentiated into all cell types of the human body, including retinal cells. This provides an unlimited supply of patient-specific retinal cells in the laboratory and offers a unique opportunity to understand the processes of retinoblastoma.
The focus of our research supported by CHECT was to use stem cells derived from retinoblastoma survivors to develop a disease model for retinoblastoma in the laboratory. The development of this stem cell model will allow us to study the mechanisms of how the mutations causing retinoblastoma affect human retinal cells and, in the future, provide a platform using patient-specific cells which can be used for testing potential drugs to treat retinoblastoma.
In this study, we first recruited retinoblastoma survivors with known mutations in the RB1 gene and obtained skin samples. Using a Nobel prize-winning technology developed at Prof. Shinya Yamanaka’s laboratory, we reprogrammed the skin cells into stem cells (called induced pluripotent stem cell, iPSC). We then directed the stem cells to develop into ‘retinal organoids’, which are often referred to as ‘mini-retina’, consisting of cells organised in a 3D structure similar to the retina. By analysing the RNA (an essential molecule in cells), we measured the gene expression of the retinal cells derived from retinoblastoma survivors and identified the cancer gene signature caused by RB1 mutation.
We then used CRISPR gene editing technology to generate cell lines to inactivate the RB1 gene and observed a similar cancer gene signature when the cells were developed into retinal cells. These results show that we have successfully developed a stem cell model for retinoblastoma, which allows us to study retinoblastoma on a lab dish, and provides an important tool for future studies to test and develop drugs to treat retinoblastoma.
This project would not be possible without the generous support from CHECT, which enabled us to initiate this work to develop a stem cell model to study retinoblastoma. Building on this work, we were able to obtain further funding from other programs such as the University of Melbourne Therapeutic Technologies Research Seed Funding, The Ophthalmic Research Institute of Australia and the Bayer Global Ophthalmology Awards Program to continue and expand on this retinoblastoma research. We are deeply grateful to the supporters of CHECT in helping us advance our research to better understand the progression of retinoblastoma and we hope that our research would one day aid in the development of new treatments to help retinoblastoma patients.