“I did my PhD in the lab of Hans Clevers at Hubrecht Institute. At that time, Toshiro Sato had just discovered organoids, which are miniature laboratory-grown versions of organs. Organoids mimic the genetics, cell composition, and structure of their source materials. Organoids created from human tissue provide a great model to study human development and disease. I started my own research group not long after my PhD graduation. After pioneering stem cell imaging in mice and organoids during my PhD, I was driven by the challenge to advance our abilities to study live-cell biology in organoids,” says Snippert.

“In the past, we applied our technological expertise to a variety of research questions. In the last two years, our activities have converged to a research question that is both intriguing from a fundamental science point of view and clinically relevant: How do benign tumours transform into malignant cancers that invade surrounding tissues and metastasize to other body parts? This pivotal transitioning stage that is 'halfway' tumour evolution is relatively understudied. Many researchers study either the earliest stages of cancer (e.g., the mutagenesis process, or the start of tumour growth), or the latest stages (i.e., metastasis). Long periods of time can precede malignant transformation, and not all benign tumours will make this transition. It seems as if a tumour needs to fulfil certain prerequisites to become malignant. This intrigues me.” 
 
“At present, we are mainly studying malignant transformation in colon cancer. We are working with organoids derived from early-stage colon cancers. It used to be difficult to obtain samples from early-stage colon cancer because most patients had already progressed towards an advanced stage upon first consultation with a clinician. With the introduction of the national screening program for colorectal cancer, tumours are generally discovered at a much earlier stage. This is important for patient care because earlier detection is associated with less invasive treatments and more favourable outcomes. In addition, it enables us to obtain samples from colon cancers that just underwent the process of malignant transformation. Joris Hageman and Julian Buissant des Amorie are PhD candidates that are working on this topic in my lab,” says Snippert. 

“We receive small biopsies from colon cancer patients that underwent surgery. To develop organoids, the biopsies are cut in small fragments, treated with enzymes, and mixed with a gel that provides support. Next, we add a liquid culture medium with growth factors,” explains Hageman. We can keep these mini tumours alive forever and use them for experiments. Importantly, we make organoids from different anatomical regions of the same tumour, ranging from healthy tissue and benign tumour tissue to malignant tumour tissue, and the invasive tumour border. Hence, a biobank with paired organoids is developed that is representative of the successive stages along the evolutionary path of the tumour,” he adds. 
 
“We perform extensive characterization of the different tumour regions, evaluating both the tumour cells and their local environment within the tumour,” Buissant des Amorie continues. "This means that we characterize the DNA, its alterations, and the gene expression patterns of the cells. We even characterize the patient samples at the level of single cells, distinguishing different cell types such as epithelial, mesenchymal, and immune cells. However, characterizing the tumours through sequencing alone does not allow us to disentangle cause and effect. That is where the organoids come in, because we can study the behaviour of the tumour cells in the region-specific organoids. In these experiments, we remove certain growth factors from the medium (or add factors) to observe which tumour cells still manage to grow,” he adds. Malignant cells tend to grow relatively independently from growth factors. The researchers also run microscopy studies, for instance to monitor real-time fluctuations in signalling activities or to trace the fate of specific cell types upon their genetic labelling with fluorescent marker genes. “By charting the causes and consequences of the differences between the successive stages of tumour evolution,” explains Buissant des Amorie, “we aim to identify factors that determine why and when malignant transformation takes place, and which new-born cancers are at direct risk to metastasize.”

At present, Snippert’s lab is running a fruitful collaboration with gastroenterologist Leon Moons, pathologist Miangela Laclé and the Utrecht Platform for Organoid Technology (UPORT) that facilitates project logistics. “We are jointly performing exciting science where we think we can make a difference. Intriguingly, some patients with a very early stage of colon cancer are already metastatic. Unfortunately, it is difficult to identify these high-risk patients because pathologists can only examine the resected primary tumours,” says Snippert, going on to explain that “far more patients are advised to undergo follow-up surgery than would have been necessary. There is a need to identify the high-risk patients more precisely because follow-up surgery is associated with a substantial risk of complications. We use the complete array of technologies that are available in our lab to improve our understanding and advance accurate stratification. This is a stimulating project. It addresses our nerdy desire to study the fundamentals of tumour evolution as well as a pressing clinical need.”

“This research line was made possible by Oncode Institute. Oncode Investigators receive a research budget that they can spend as they see fit. As a result, we could start this research line without immediate dedicated funding, providing sufficient confidence to go off the beaten track and explore a unique research opportunity that presented itself. Moreover, characterizing organoids and tumour samples by modern technologies is quite costly. Most research grants do not easily cover such costs. Needless to say, another great advantage of being part of Oncode is the opportunities for amazing collaborations. I find these collaborations very inspiring. We have a common goal to produce fundamental insights that will eventually improve patients’ lives,” says Snippert. 
 
Buissant des Amorie finds inspiration in working with others: “It is very motivating to collaborate with so many different experts, ranging from gastroenterologists and pathologists to bio-informaticians,” he says. Hageman agrees: “We spend a lot of time exchanging ideas with our colleagues, trying to determine the next clever step in our research. Conceptually, the topic of malignant transformation is very broad, allowing a lot of room for creativity and flexibility. We are constantly adapting and trying to focus on topics where we can make a difference.” 

Credits: interview by Koen Scheerders; photography by Marloes Verweij, Laloes Fotografie