Project title: Generation and characterization of a novel genetically modified patient–derived NET organoid system

Project Description:

The slow growth of NETs makes their in-vitro propagations very challenging and many experimental approaches impractical. The paucity of clinically relevant models has limited progress in the field. Dr. Yao and his team will develop a new NET model system that will enable them to turn on growth to induce enough NET cell growth to conduct experiments. Importantly, this model will also allow them to subsequently turn off a growth switch to return the NET cells to their original biology for use in broad drug screening trials to identify the drugs or drug combinations that may most effectively destroy NETs.

What critical NET problem will you try to solve through your research?

The diagnosed incidence of NETs continues to rise. While slow growing, NETs are lethal when advanced. Development of effective therapy has been limited by a lack of clinically relevant laboratory models that can enable screening of new treatments. In this project, Dr. Yao and his team will generate a biobank of intestinal and pancreatic NET models to represent the spectrum of diversity in human NET behavior.

Why is this important?

The very slow-growing nature of well-differentiated NETs makes it difficult to develop NET models in laboratories. On average, human NETs take 5-18 months to grow even 20%. Under such conditions, it is very difficult to keep NET cells alive in the laboratory, and even if possible, it may take years to conduct even a single experiment.

What will you do as part of this research project?

We propose a novel approach by genetically modifying human-derived NET cells to insert a growth switch that can be controlled by doxycycline, a common antibiotic. This will enable us to “turn on” the growth switch to induce NET cells to grow to a sufficient amount to conduct experiments and subsequently “turn off” the growth switch to return the NET cells to normal biology.

How might your research improve the diagnosis and/or treatment of NETs? 

Successful execution of the project will help us to create a bank of pancreatic and intestinal NET models to represent the spectrum of diversity in human NET behavior. This will let us test promising new therapies quickly in the lab. 

What is your next step?

We will generate a library of human NET models and genetically and molecularly characterize these models to ensure our models are useful in studying human NETs and testing new treatments. 

Outcomes:

Well-differentiated gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are slow–growing cancers with an increased incidence rate. While progress has been made, these cancers remain incurable when they have spread. The development of new treatments is severely hindered by the scarcity of clinically relevant models in laboratory. Human GEP-NETs have been proven difficult to grow in culture and animal models precisely due to their sluggish growth rates. While certain genetic manipulations may accelerate these tumor growths, most manipulations fundamentally change the tumor biology, resulting in the models that no longer accurately reflect human neuroendocrine tumor biology. Thus, we have worked on a novel unique approach that involves the introduction of genetic materials designed to induce rapid growth in human neuroendocrine tumors, controlled by an “on/off switch”. This innovative approach allows us to overcome the hurdle of establishing patient-derived clinically relevant GEP-NET models in laboratory by turning “on” the switch to activate a growth stimulus to obtain sufficient materials; it also allows us to subsequently deactivate the extra genetic material by turning “off” this switch to restore the models to their original slow–growing neuroendocrine tumor biology. The proposed goal of this project is to generate new laboratory models of GEP-NETs that closely mimic human GEP-NETs by using this approach, enabling the testing of new drugs in these models.

We have diligently worked and made substantial progress with this 1 year-pilot award support of NETRF. 1) We have developed an inducible lentivirus system marked with ‘green” fluorescent protein and inserted with the optimized sequence of genetic material known to accelerate the tumor cell growth (i.e., SV40LT; TP53R273H). This system is controlled by a promoter that can be “switched on and off” in the presence and absence of doxycycline, a common antibiotic. Subsequently, we optimized the protocols for 3D primary tumor cell culture and lentivirus infection conditions to generate the models derived from surgically resected human neuroendocrine tumors collected from MD Anderson tissue bank. 2) We have attempted to generate the models using our novel approach on 21 patients with GEP-NETs including 11 pancreatic neuroendocrine tumors and 10 intestinal neuroendocrine tumors. After learning from our initial few attempts, we have successfully developed 12 innovative patient-derived cancer models that recapitulate the genomic and phenotypic features of human G1/G2 GEP-NETs, achieving an overall success rate of 57.1% (12/21). This study presents a breakthrough in modeling slow-growing G1/G2 GEP-NETs. These models yield unique materials and resources that enable advancements in translational studies for GEP-NETs such as conducting drug screening experiments in these models to identify new effective therapeutic strategies.

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