Values of 5mC, 5hmC, and TET2 for identifying the presence and progression of breast precancerous lesion

BACKGROUND: This study aimed to evaluate the correlations of 5‐methylcytosine (5mC), 5‐hydroxymethylcytosine (5hmC), and ten‐eleven translocation enzyme 2 (TET2) expressions in lesion tissue with histological classification of breast precancerous lesion. METHODS: Eighty‐three patients with breast ductal intraepithelial neoplasia (DIN), 20 patients with breast ductal carcinoma in situ with microinvasion (DCIS‐MI), and 10 patients with invasive breast cancer were included. Histological classification of the DIN patients was classified as DIN1A, DIN1B, DIN1C, DIN2, and DIN3. 5mC, 5hmC, and TET2 expressions in lesion tissues from biopsy were assessed by immunohistochemistry (IHC) assay. RESULTS: 5hmC and TET2 were negatively associated with histological classification as validated by both IHC score and IHC semi‐quantification expression grades in total patients (all P < .05); however, no correlation of 5mC with histological classification was found (all P > .05). 5mC (P = .004) was negatively but 5hmC (P < .001) was positively correlated with TET2, while no association of 5mC with 5hmC was discovered in total patients (P = .078). In addition, 5mC was positively associated with ER expression in total patients (P = .040). In subgroups, 5mC was negatively correlated with 5hmC in DIN1C patients (P = .023) and invasive cancer patients (P = .044), and 5mC was negatively associated with TET2 in DIN1B patients (P = .004) as well as DCIS‐MI patients (P = .003). CONCLUSION: 5hmC and TET2 have the potentials to serve as biomarkers that could assist in the identification of presence and progression of breast precancerous lesion.