miRNA-mediated alteration of sulfatase modifying factor 1 expression using self-assembled branched DNA nanostructures.

Sulfatase enzymes catalyze sulfate ester hydrolysis, thus deficiencies of sulfatases lead to the accumulation of biomolecules resulting in several disorders. One of the important sulfatases is estrone sulfatase that converts inactive estrone sulfate to active estradiol. Posttranslational modification of highly conserved cysteine residue leads to unique formylglycine in the active site of sulfatases being critical for its catalytic activity. The essential factor responsible for this modification of sulfatase is Sulfatase-Modifying Factor 1 (SUMF1). The role of estrone sulfatase is well evident in breast cancer progression. However, the function and regulation of SUMF1 in cancer are not studied. In the present study, for the first time, we have assessed the expression of SUMF1 in breast cancer and report the oncogenic behavior upon overexpression of SUMF1. Although increased expression or activity of SUMF1 is anticipated based on its function, the expression of SUMF1 was found to be reduced in breast cancer cells at both mRNA and protein levels. An estrogen receptor (ER) dependent expression of SUMF1 was observed and higher SUMF1 expression is associated with improved breast cancer patient survival in ER-positive cases. However, high SUMF1 expression leads to reduced median survival in ER-negative breast cancer patients. Putative binding sites for miRNAs-106b-5p, 128-3p and 148b-3p were found at 3'-UTR of SUMF1. Since self-assembled branched DNA (bDNA) structures have emerged as a highly efficient strategy for targeting multiple miRNAs simultaneously, we studied the alteration in SUMF1 expression using bDNA nanostructures with a complementary sequence to miRNAs. The findings suggest the involvement of co-regulators and repressors in miRNA-mediated SUMF1 expression in breast cancer cells and reveal the therapeutic potential of SUMF1 in endocrine-related malignancies.