How Cells Slow Cancer That Has Reached Bone

Patients who are treated for their primary cancer may have it return in their bones 20 or even 30 years later. Now, new research published in Breast Cancer Research may have identified why this phenomenon happens, which in turn may help researchers identify new treatments to permanently stop the growth of cancer cells.

The study identified a type of bone cell that subdues cancer cells and slows their growth so that the cancer cells can remain in a sleeping state and reawaken decades later.

“Cancer has this uncanny ability to turn other cell types it comes in contact with to the cancer cell’s advantage,” Karen Bussard, PhD, coauthor, assistant professor of cancer biology at Thomas Jefferson University and a researcher at the Sidney Kimmel Cancer Center, Jefferson Health, said in a statement. “For example, cancer cells can turn the immune cells that should kill it, into its own guards. However, we have now found a population of bone cells that not only resists but subdues the cancer. It’s fascinating.”

The researchers studied the tumor-bearing tibia of mice for the presence of osteoblasts and analyzed tissue from patients with bone metastatic breast cancer for osteoblast subpopulations.

They found that once osteoblast cells in both mice and humans interacted with bone metastatic breast cancer cells, they were drastically changed. Once cancer cells enter the bone, osteoblasts change their function toward producing factors that halt cancer cell growth.

The findings could help develop new strategies to prevent or treat metastatic disease. Next, the researchers will fully characterize the molecules used by osteoblasts to slow cancer growth. It might be possible that understanding the function of these osteoblasts could provide treatments that put cancer cells to sleep permanently.

“The bone-building osteoblast cells have a complex relationship with cancer,” Bussard said. “In advanced stages of the disease, we know that metastatic breast cancer cells can co-opt the normal cells of the bone to help cancer metastases thrive. However, our new work suggests that during early stages of the disease, such as when metastatic breast cancer cells first migrate to the bone, these cancer-exposed osteoblasts resist and fight cancer growth.”

Reference

Kolb AD, Shupp AB, Mukhopadhyay D, Marini FC, Bussard KM. Osteoblasts are “educated” by crosstalk with metastatic breast cancer cells in the bone tumor microenvironment. Breast Cancer Res. 2019;21(1):31. doi: 10.1186/s13058-019-1117-0.