The importance of 3D culture for the study of driver oncogenes

A driver oncogene is a gene that, when activated by mutation or altered in expression, contributes importantly to the development and progression of cancer. In other words, alteration of this kind of genes lead to the transformation of a normal cell into a cancerous cell by activating signaling pathways involved in the promotion of various cell responses as cell growth, survival, invasion, …

The development of high-throughput sequencing techniques in clinical routine has allowed the identification of numerous driver oncogenes involved in almost all cancers. Since mutated tumor cells are dependent on this oncogene for growth, this alteration can become the Achilles heel of the tumor. These discoveries paved the way to the development of targeted therapies against these oncogenes drivers for cancer treatment. By specifically acting against the tumor cells, these therapies are more effective while reducing toxicity compared to conventional chemotherapies.

The efficacy of therapies is usually tested in two-dimensional cell culture before evaluation in the mouse model. 2D cell culture has too many limitations to accurately study the efficacy of these therapies and subsequently lead to too many failures in preclinical trials in mice. The development of evaluation methods more representative of biological reality is crucial if we really want to reduce the animal experimentation required for the pre-clinical validation of treatments. This general fact is also true in the area of oncogenes and targeted therapies.

KRAS is an intracellular kinase protein and one of most frequently mutated oncogene in many various cancers. Emblematic KRAS mutant cancers are pancreatic (more than 80% of cases), colorectal (> 30%) and lung adenocarcinomas (> 25%)¹. The main alteration detected is the activating mutation affecting the G12 residue in the kinase leading to its unregulated activation. Interestingly, it has already been shown that cancer cell proliferation involving the KRAS oncogene is only revealed in 3D culture. Indeed, it was showed that cell viability and proliferation in monolayer 2D cultures did not differ between ovarian cancer cells expressing or not expressing the KRAS mutant oncogene². They also showed that KRAS accelerated tumour formation by modulating the tumour microenvironment³.

KRAS mutations have long been considered as difficult therapeutic targets, as they were said “non-druggable”. However, in recent years, significant advances have been made in the development of therapies targeting KRAS mutations and the results of preliminary studies are very encouraging. The question is whether the use of 2D models in this particular context has been a limitation to the discovery of truly efficient molecules?

In this way, BIOMIMESYS® matrix, a hyaluronic acid based hydroscaffold™ grafted with structural components that mimics the extracellular matrix could help to the development of new efficient therapies targeting KRAS mutant tumor cells. The composition and the stiffness of BIOMIMESYS® are modular, that is why it can be adapted to reproduce the tumoral extracellular matrix, which is enriched in type I collagen I and hence, more rigid.

Sources:

1.            Timar, J., and Kashofer, K. (2020). Molecular epidemiology and diagnostics of KRAS mutations in human cancer. Cancer Metastasis Rev. 39, 1029–1038. 10.1007/s10555-020-09915-5.

2.            Ogishima, J., Taguchi, A., Kawata, A., Kawana, K., Yoshida, M., Yoshimatsu, Y., Sato, M., Nakamura, H., Kawata, Y., Nishijima, A., et al. (2018). The oncogene KRAS promotes cancer cell dissemination by stabilizing spheroid formation via the MEK pathway. BMC Cancer 18, 1201. 10.1186/s12885-018-4922-4. 3.            Yoshida, M., Taguchi, A., Kawana, K., Adachi, K., Kawata, A., Ogishima, J., Nakamura, H., Fujimoto, A., Sato, M., Inoue, T., et al. (2016). Modification of the Tumor Microenvironment in KRAS or c-MYC-Induced Ovarian Cancer-Associated Peritonitis. PLoS ONE 11. 10.1371/journal.pone.0160330.