Lung cancer is the leading cancer killer in the U.S. It is often missed in its earlier stages, and while recent imaging advances have enabled earlier detection, there are still no targeted treatments for early-stage lung cancers. New research from Boston Children’s Hospital, in collaboration with Boston University and UCLA, provides an accelerated platform for identifying and testing potential treatments: “organoids” created from lung cells.
As reported September 4 in Cell Stem Cell, the organoids enabled the researchers to track one common, hard-to-treat lung tumor — adenocarcinoma driven by mutation in the KRAS gene — from its origins, capturing the molecular changes that took place as it progressed.
The research team, led by Carla Kim, PhD, of Boston Children’s Stem Cell Program, used four parallel models of early lung cancer: tumor samples from patients with early (stage 1A) lung cancer, genetically engineered mouse models, and lung organoids derived from either mouse lung stem cells or from lung cells created from human induced pluripotent stem cells.
“We know very little about the early events that transform a normal lung epithelial cell into a cancer cell,” says Kim, co-senior author on the paper with Jane Yanagawa, MD, of UCLA and Darrell Kotton, MD, of the Boston University School of Medicine. “In this study, we were able to use early-stage samples from lung cancer patients to show that our organoids truly mimic what happens in patients at the very early stages. We can see changes in the organoids within seven days that can take months to see in mice and even longer, probably years, in patients.”
Tracking an unfolding lung cancer
The researchers introduced the cancer-initiating KRAS mutation into the lung organoids’ alveolar progenitor cells. They then used single-cell RNA sequencing to see what genes turned on, or expressed, as a result. These studies revealed reduced expression of genes that are markers of mature lung alveolar cells, and increased expression of genes involved in early lung development — known markers of cancer progression. Studies in mice and in the patient tumor samples mirrored findings in the organoids.
“KRAS-mutant tumors are usually already resistant to therapy by the time they are diagnosed,” notes Kim. “These studies lay a groundwork for finding new therapeutic avenues in the future when an early-stage lung cancer is detected.”
Although this study looked at KRAS-driven lung cancer, the researchers believe that the organoid approach could facilitate the study of other kinds of cancer, including testing of candidate drugs.
“The collaborating teams really made progress together in understanding a stage of lung cancer that has been very tough to study in humans,” says Kotton. “We hope these new human and lung organoid models of early lung cancer formation will now serve as powerful drug development platforms.”