Technologies

This invention is directed to the treatment of breast cancer in a subject, particularly triple-negative breast cancer, with guide RNA (gRNA) probes for modifying the genetic code of the TCOFl gene, thereby inhibiting the expression of TCOF 1. The gRNA probes comprise a nucleotide sequence which is 20 nucleotides in length, and which is substantially complementary to at least a part of the TCOF 1 gene. The invention relates to methods for treating cancers caused by TCOF 1 expression.