Exploring the interaction between extracellular matrix components of bone marrow and prostate cancer cells in a novel 3D model

When cancer spreads from its original site to the bones, it often hides in a deep, protective layer called the bone marrow. This environment is not just a passive storage space; it is a complex neighborhood filled with living cells and a sticky, structural framework known as the extracellular matrix. Think of this framework as the scaffolding that holds the neighborhood together. For years, scientists have known that cancer cells hiding in this bone marrow can become dormant, or go to sleep, making them invisible to standard chemotherapy drugs. While researchers have studied how cancer cells talk to their neighbors, the specific way these cells interact with the sticky scaffolding itself has remained a mystery. Understanding this interaction is crucial because it may explain why some patients relapse years after treatment, with dormant cells waking up to cause new, dangerous tumors.

A team of researchers at the University of Rochester Medical Center set out to solve this puzzle by building a new, three-dimensional model that mimics the bone marrow's scaffolding. Instead of growing cancer cells on flat plastic dishes, which does not reflect how they behave in the human body, the scientists created a porous sponge made from a natural material found in umbilical cords. They stripped away all the living cells from this material, leaving behind only the structural proteins that resemble the bone marrow's environment. They then placed two common types of prostate cancer cells onto this sponge to see how they would react. The goal was to observe whether the physical environment alone could change the cancer cells, making them resistant to drugs or turning them into a more dangerous, stem-like state.

The results showed that the environment of the sponge had a profound effect on the cancer cells. When the cells grew within this three-dimensional structure, they became significantly harder to kill with a standard chemotherapy drug called Docetaxel. The cells also slowed down their growth, entering a dormant state similar to the sleep phase that allows them to survive treatment in the body. However, the most striking discovery was that this environment did not affect all cancer cells in the same way. One type of prostate cancer cell, known as DU145, began to change its identity. After spending a week on the sponge, a small group of these cells, about five percent of the total, started to display markers of cancer stem cells. These are the rare cells within a tumor that have the unique ability to start new growths and resist therapy. The other type of cell they tested, PC-3, did not undergo this same transformation, suggesting that the ability to change depends on the specific type of cancer cell involved.

To confirm that these changed cells were indeed more dangerous, the researchers took the small group of altered cells and injected them into mice. They found that these cells could start new tumors with far fewer numbers than the original, unaltered cancer cells. While the original cells needed a million to form a tumor, the altered cells could start a tumor with just a few thousand. Furthermore, when these new tumors were examined, they showed signs of having spread more aggressively. The cells had also changed their shape, becoming more elongated and flexible, a physical shift that often helps cancer cells travel through the body. This suggests that the bone marrow's scaffolding does more than just shelter cancer cells; it can actively reprogram a small subset of them into a more resilient and dangerous form.

The study highlights that the physical structure of the bone marrow plays a critical role in how prostate cancer behaves. By creating a model that accurately mimics this structure, the researchers were able to see how the environment itself triggers changes in the cancer cells. They observed that the interaction between the cell and the scaffolding can induce a dormant state and a shift toward a stem-like identity, which are key factors in treatment resistance. While the researchers noted that they still need to identify exactly which parts of the scaffolding cause these changes, their work provides a clear path forward. It suggests that to prevent cancer from returning, doctors may need to target not just the cancer cells, but also the specific environment that allows them to hide and evolve. This new model offers a powerful tool for testing how to break the connection between the cancer and its protective home, potentially leading to better ways to treat metastatic disease.