Cell fate decisions and fatal consequences: How cancer seeds can choose a life less travelled

Rare tumour cells have recently been identified in breast cancers that share many stem cell properties that allow them to evade conventional treatments and go on to sow the seeds of tumour recurrence and metastasis (spread) with ultimately fatal consequences.

To successfully target these cells in the clinic we must first understand what characteristics are critical for their function. One property, universal to all stem cells, is the ability to divide in a way that retains pools of stem-like cells whilst also allowing the generation of a diverse array of daughter cells.

This process, known as asymmetric cell division, is essential during development, but can go horribly awry in cancer. The impact of asymmetric cell division in breast cancer progression is unknown.

Dr Patrick Humbert and his team have recently identified the asymmetric cell division gene Gpsm2, which is a breast cancer tumour suppressor, and shown that it is essential for regulating the growth of normal breast stem cells. They also found that Gpsm2 can alter cancer stem cells and restrict the spread of breast cancer to the lungs of mice.

Dr Humbert is investigating this poorly-examined central aspect of stem cell biology to better understand how it resists therapy and enables cancers to metastasise. He believes that, similar to its role in regulating the numbers and function of normal stem cells, Gpsm2 also acts as a critical regulator of cancer stem cells.

Importantly, this could be a completely new target for stopping breast cancer recurrence and metastasis which could lead to the development of more effective treatments for all late-stage breast cancer patients.

Examination of this new anti-tumour pathway could also identify a completely new pathway to target hormone receptor negative breast cancer therapeutically and offer hope to women with basal-like and Her2+ breast cancers that currently lack effective treatments.