Therapeutic methods for preventing tumor metastasis and tumor recurrence

Abstract

Cancer stem cells are responsible for tumor recurrence, distant metastasis and drug-resistance, in the vast majority of cancer patients. There exists an urgent need to identify new mitochondrial inhibitor drugs that can target and eradicate CSCs, and companion diagnostics to identify candidates for mitochondrial inhibition therapy. In 3D mammospheres, 25 mitochondrial-related proteins were over 100-fold over-expressed in a large collection of transcriptional profiling data from ER(+) breast cancer patients. These 25 proteins may be used to derive short gene signatures to predict the likelihood of distant metastasis and tumor recurrence. For example, the 4-gene signature of ACLY, VDAC3, HADH2, and COX6B1 may be used for predicting the likelihood of distant metastasis, with a hazard ratio of 1.91-fold (P=2.2e−08). A pharmaceutically effective amount of a mitochondrial inhibitor may be administered to a candidate having elevated expression of the genes in a gene signature. Five example mitochondrial inhibitors showed preferential and selective inhibition of tumor cell metastasis, without causing significant toxicity. Mechanistically, all five mitochondrial inhibitors have been previously shown to induce ATP-depletion in cancer cells. Gene signatures composed of 6-9 large mitochondrial ribosomal proteins also show prognostic value in predicting distant metastasis, tumor recurrence, and Tamoxifen resistance, in both ER(+) and ER(−) breast cancer patients. The disclosed gene signatures may be used as companion diagnostics to assess which patients may benefit most from mitochondrial inhibition therapy.