Introduction: Cancer cells have mutations which contribute to their pathogenesis and cause them to rapidly grow and divide inappropriately. In pancreatic cancer, almost all tumors have activating mutations in an important protein called RAS which tells cells to divide. Pancreatic cancer cells also have short, small mitochondria that somehow help them survive. This is the opposite of healthy cells, which have a mixture of long and short mitochondria. This is also interesting, as in normal cells long mitochondria are better at making energy. We are interested in understanding how a RAS mutation changes cancer cells to cause them to favor short mitochondria.
Hypothesis: If we use chemistry to inactivate DRP1 protein, the cancer cells will be forced to have long mitochondria, whereas if we inactivate OPA1 and MFN1 protein, the cells will have short mitochondria. If we force cancer cells to have long mitochondria, they will grow more slower than control cells.
Experimental method: Short interfering RNA (siRNA) are molecules that researchers use to “knock down” a protein, or make it so the cell don’t produce it. We utilized siRNAs for DRP1, OPA1, and MFN1 to make mitochondria long or short and quantified our results. We then measured how DRP1, OPA1, or MFN1 knockdown changed cell growth
- DRP1 knockdown= Fusion
- OPA1 knockdown= Fragmentation
- MFN1 knockdown = Fragmentation
Conclusions: knocking down mitochondrial dynamin proteins seems to be a viable method of manipulating mitochondrial morphology. Two out of the three cell lines we tested exhibited a robust decrease in cell growth upon genetic silencing of DRP1, however, strikingly, one line did not respond to DRP1 loss with a growth defect. Our results show that targeting mitochondrial morphology proteins is an exciting potential therapeutic for PDAC patients, and differences in mitochondrial morphology may contribute to heterogeneity in treatment response between patients. The existence of leflunomide, an FDA-approved arthritis drug that increases MFN1 transcript levels and mitochondrial fusion, makes this avenue of treatment particularly exciting.