Topping up Mitochondrial Content to Fight Kidney Cancer
Researchers at Karolinska Institutet in Sweden have linked resistance to treatment for VHL syndrome-induced kidney cancer to low mitochondrial content in the cell. When the researchers increased the mitochondrial content with an inhibitor, the cancer cells responded to the treatment. Their findings, which are published in Nature Metabolism, may lead to more targeted cancer drugs.
Mitochondria are the most oxygen-demanding component of the cell, but it was not known how mitochondria adapt in a low-oxygen environment and how they are linked to cancer therapy resistance.
“We’ve shown for the first time how the formation of new mitochondria is regulated in cells that lack oxygen and how this process is altered in cancer cells with VHL mutations,” explained Associate Professor Susanne Schlisio, group leader at the Karolinska Institutet.
A gene called von Hippel-Lindau (VHL) prevents healthy cells from turning cancerous. The 2019 Nobel Prize in Physiology or Medicine was awarded to the discovery that VHL was part of the cell’s oxygen detection system. Normally, VHL breaks down another protein called HIF – but when VHL is mutated, HIF accumulates and causes a disease called VHL syndrome in which the cells react as if they were lacking oxygen. This syndrome greatly increases the risk of tumours, both benign and malignant. VHL syndrome-induced kidney cancer has a poor prognosis, with a five-year survival rate of just 12%.
Researchers analysed the protein content of cancer cells from patients with different variants of VHL syndrome, to see how they differed from another group of individuals with a special VHL mutation called Chuvash, a mutation involved in hypoxia-sensing disorders without any tumour development. Those with the Chuvash VHL-mutation had normal mitochondria in their cells, while those with VHL syndrome mutation had few.
To increase the amount of mitochondrial content in VHL related kidney cancer cells, the researchers treated these tumours with an inhibitor of a mitochondrial protease called “LONP1.” This resulted in the cells becoming susceptible to the cancer drug sorafenib, which they had previously resisted. In mouse studies, this combination treatment led to reduced tumour growth.
The study’s first author Shuijie Li, postdoctoral researcher in the Schlisio’s group, suggested that the findings could be applied to more than just VHF syndromic kidney cancers.
“We hope that this new knowledge will pave the way for more specific LONP1 protease inhibitors to treat VHL-related clear cell kidney cancer,” Dr Li said. “Our finding can be linked to all VHL syndromic cancers, such as the neuroendocrine tumours pheochromocytoma and paraganglioma, and not just kidney cancer.”
Source: Karolinska Institutet
