Cancer Cells Transfer Mitochondria to Neighboring Cells to Support Tumor Growth

Research conducted at ETH Zurich has uncovered a novel mechanism by which cancer cells actively transfer their mitochondria to nearby healthy connective tissue cells, known as fibroblasts. This mitochondrial transfer enables the fibroblasts to transform into tumor-associated fibroblasts that significantly support tumor progression. The process involves tiny membrane tubes that function similarly to pneumatic systems, allowing mitochondria to be transported from cancer cells into adjacent cells.

This transfer reprograms the fibroblasts, causing them to multiply faster, produce more ATP (the cell's energy currency), and secrete elevated levels of growth factors and cytokines—all of which foster a more aggressive tumor environment. Moreover, these altered fibroblasts modify the extracellular matrix, increasing tissue components that further facilitate tumor growth.

The discovery was serendipitous, originating from observing cell connections between cancer and fibroblast cells in petri dish cultures. The research revealed that mitochondria can be exchanged bidirectionally—an insight that was previously limited to unidirectional transfer from healthy cells to damaged nerve cells after strokes. The findings suggest that tumors exploit this cellular communication for their survival and expansion.

Additionally, the study identified the protein MIRO2 as a crucial molecule mediating the transfer of mitochondria. High levels of MIRO2 were observed in cancer cells involved in mitochondrial transfer, especially at tumor edges where cells invade healthy tissue. Blocking MIRO2 in laboratory and animal models inhibited mitochondrial transfer and prevented fibroblasts from becoming tumor-promoting, indicating potential therapeutic targets.

While these results are promising, further research is needed to develop inhibitors that can effectively block MIRO2 in humans without adverse effects. If successful, such therapies could slow down or halt tumor growth by interrupting these mitochondrial exchanges. Overall, this study highlights a sophisticated method tumors use to manipulate their environment and offers new avenues for cancer treatment.