Many different types of cells in the body have a tiny projection known as a primary cilium. These cilia act like little signaling hub that can capture information about a cell's environment and relay it to the cell, ultimately coordinating some cellular responses. The functions of cilia are well known in a few cases, such as in development, where they are crucial to the regulation of certain processes; or in some disorders called ciliopathies, in which genetic mutations lead to ciliary dysfunction and human disease.
But there is still a lot we don't know about cilia in many cell types, such as neurons or cancer cells. Scientists have learned, however, that cilia may be critical to the growth of some cancers, and problematic for others; some cancers seem to use cilia to grow while others eliminate cilia. A new review reported in Oncogene has outlined how cilia could be important to the growth or resistance of cancer.
"We're only just beginning to understand how powerful these structures are in cancer," said Dr. Barbara Tanos at Brunel University of London. "They work like a Rubik's cube. If each side of the cube contains instructions for the cell to perform one function, rotating one layer of the cube changes the instructions from every side."
Some types of cancer cells appear to use some ciliary molecules so that instead of performing their normal functions, they begin to promote tumor formation and growth by activating biochemical pathways. Cancer is related to unchecked cell growth, and cilia seem to help activate that in some cases. They help cancer proliferate uncontrollably, invade other tissues, and resist therapeutics.
But they could also be a target for new cancer treatments. Some ciliary molecules are already targeted by existing drugs as well, noted Tanos.
"Once we identify new mechanisms of how cilia control cancer growth, this can help uncover drug targets within ciliary signaling pathways. If the medicines are already available, this can be quite soon. Cilia itself can also be the target, and there are drugs that inhibit proteins that mediate the formation of cilia."
Cilia were once assumed to be unrelated to cancer. But studies have suggested that in some cases, they are crucial to tumor adaptation and resistance. "The role of cilia in cancer is, in itself, unexpected," said Tanos.
The researchers had thought cancer cells may not have cilia. And while some do not, others seem to rely on them, particularly for drug resistance, said Tanos.
Previous work by this group has explored the link between cilia and drug resistant cancer. Their work indicated that cancer cells that become resistant to kinase inhibitors, which are meant to stop cancer cells from growing, also had lengthier cilia and more of them compared to cancer cells that were susceptible to drugs.
There is more to learn, but cilia may offer scientists a new way to study and treat cancer.
Sources: Brunel University of London, Oncogene