Breast cancer is frequently the most diagnosed female
cancer in the world. The experimental studies on
cancer seldom focus on the relationship between the central nervous system and
cancer. Despite extensive research into the treatment of
breast cancer,
chemotherapy resistance is an important issue limiting the efficacy of treatment. Novel
biomarkers to predict prognosis or sensitivity to
chemotherapy are urgently needed. This study examined nervous-system-related genes. The profiling of differentially expressed genes indicated that high-LET radiation, such as that emitted by
radon progeny, in the presence of
estrogen, induced a cascade of events indicative of tumorigenicity in human breast epithelial cells. Bioinformatic tools allowed us to analyze the genes involved in
breast cancer and associated with the nervous system. The results indicated that the gene expression of the
Ephrin A1 gene (
EFNA1), the roundabout guidance receptor 1 (ROBO1), and the
kallikrein-related
peptidase 6 (KLK6) was greater in T2 and A5 than in the A3 cell line; the LIM domain
kinase 2 gene (LIMK2) was greater in T2 than A3 and A5; the
kallikrein-related peptidase 7 (KLK7), the
neuroligin 4 X-linked gene (NLGN4X), and
myelin basic protein (MBP) were greater than A3 only in T2; and the neural precursor cell expressed, developmentally down-regulated 9 gene (NEDD9) was greater in A5 than in the A3 and E cell lines. Concerning the correlation, it was found a positive correlation between ESR1 and
EFNA1 in BRCA-LumA patients; with ROBO1 in BRCA-Basal patients, but this correlation was negative with the
kallikrein-related
peptidase 6 (KLK6) in BRCA-LumA and -LumB, as well as with LIMK2 and ROBO1 in all BRCA. It was also positive with
neuroligin 4 X-linked (NLGN4X) in BRCA-Her2 and BRCA-LumB, and with MBP in BRCA-LumA and -LumB, but negative with KLK7 in all BRCA and BRCA-LumA and NEDD9 in BRCA-Her2. The differential gene expression levels between the
tumor and adjacent tissue indicated that the ROBO1, KLK6, LIMK2, KLK7, NLGN4X, MBP, and NEDD9 gene expression levels were higher in normal tissues than in
tumors; however,
EFNA1 was higher in the
tumor than the normal ones.
EFNA1, LIMK2, ROBO1, KLK6, KLK7, and MBP gene expression had a negative ER status, whereas NEDD9 and NLGN4X were not significant concerning ER status. In conclusion, important markers have been analyzed concerning genes related to the nervous system, opening up a new avenue of studies in
breast cancer therapy.