Histone Deacetylase Inhibitory Activity and Antiproliferative Activity of the Cultured Medium of Aspergillus niger strain TS1

Inhibition of histone deacetylase (HDAC) activity in cancer cells is a promising mechanism for cancer treatment. A screening program for fungi capable of producing HDAC-inhibiting molecules would lead to discovery of potential anticancer agents. The objective of this study was to isolate and characterize fungi capable of producing HDAC inhibitors from soil samples. Only one out of 48 soil fungal isolates exhibited HDAC inhibitory activity. Based on its morphological characteristics and the internal transcribed spacer (ITS) sequence of ribosomal RNA gene, the TS1 fungal isolate was identified as Aspergillus niger and named as A. niger TS1. The cultured medium of strain TS1 significantly inhibited HDAC activity both in vitro and in mammalian cells. The cultured medium of strain TS1 exhibited antiproliferative activity against human acute T cell leukemia cell line (Jurkat cells), human cervical cancer cell line (HeLa cells), and human colon cancer cell line (HCT116 cells). The growth inhibitory effects appeared to be mediated by induction of apoptosis. The current study demonstrates that the filamentous soil fungus A. niger TS1 can serve as a natural source of HDAC inhibitors, which could lead to the discovery of a novel anticancer agent.