tRNA Over-Expression in Breast Cancer

Increased proliferation and elevated levels of protein synthesis are characteristic of transformed and tumor cells. Though components of the translation machinery are often misregulated in cancers, how tRNA plays a role in cancer cells has not been explored. We compare genome-wide tRNA expression in tumorigenic versus non-tumorigenic breast cell lines, as well as tRNA expression in breast tumors versus normal breast tissues. In tumorigenic versus non-tumorigenic cell lines, nuclear-encoded tRNAs increase by up to 3-fold and mitochondrial-encoded tRNAs increase by up to 5-fold. In tumors versus normal breast tissues, both nuclear and mitochondrial-encoded tRNAs increase by up to 10-fold. This tRNA over-expression is selective and coordinates with the properties of cognate amino acids. Nuclear- and mitochondrial-encoded tRNAs exhibit distinct expression patterns, indicating that tRNAs can be used as biomarkers for breast cancer. We analyzed tRNA expression levels in 2 non-tumorigenic breast cell lines, 6 tumorigenic breast cancer cell lines, 3 normal breast tissue samples, and 9 breast tumor samples. We used a non-tumorigenic breast cell line (MCF10A) as a reference sample in all hybridizations. All data is dye-swapped.