Biological activities of fusarochromanone: a potent anti-cancer agent

Abstract

Background: Fusarochromanone (FC101) is a small molecule fungal metabolite with a host of interesting biological functions, including very potent anti-angiogenic and direct anti-cancer activity.

Results: Herein, we report that FC101 exhibits very potent in-vitro growth inhibitory effects (IC50 ranging from 10nM-2.5 μM) against HaCat (pre-malignant skin), P9-WT (malignant skin), MCF-7 (low malignant breast), MDA-231 (malignant breast), SV-HUC (premalignant bladder), UM-UC14 (malignant bladder), and PC3 (malignant prostate) in a time-course and dose-dependent manner, with the UM-UC14 cells being the most sensitive. FC101 induces apoptosis and an increase in proportion of cells in the sub-G1 phase in both HaCat and P9-WT cell lines as evidenced by cell cycle profile analysis. In a mouse xenograft SCC tumor model, FC101 was well tolerated, non-toxic, and achieved a 30% reduction in tumor size at a dose of 8 mg/kg/day. FC101 is also a potent anti-angiogenenic agent. At nanomolar doses, FC101 inhibits the vascular endothelial growth factor-A (VEGF-A)-mediated proliferation of endothelial cells.

Conclusions: Our data presented here indicates that FC101 is an excellent lead candidate for a small molecule anti-cancer agent that simultaneously affects angiogenesis signaling, cancer signal transduction, and apoptosis. Further understanding of the underlying FC101's molecular mechanism may lead to the design of novel targeted and selective therapeutics, both of which are pursued targets in cancer drug discovery.

Figure 1

Structure of fusarochromanone (FC101).

Figure 2

Comparison of the dose-response and time-response impact of FC101 treatment on cell viability of seven cell lines. A-G: A540 is the absorbance at 540 nm, which positively correlates with cell number. Error bars are shown for triplicate cultures. The graphs are representative of at least three experiments having similar results. H: The percent growth inhibition at day 4, calculated as (A540C-A540T/A540)x100, where A540C is the control value and A540T is the treated value. The graph lines in A-G are color matched to the bars in H.

Figure 3

Cells were plated at a density of 1.5 × 10 ⁶ cells/10 cm plate and treated the following day with 10 μM FC101. Cells were photographed on a phase contrast microscope at 100X magnification.

Figure 4

Differential effect of FC101 on cell cycle distribution and apoptosis induction in HaCaT and SRB12-p9 cells. Cells were plated and treated as in described in Figure 3 and harvested for FACS analysis. Y-axis indicates cell number, X-axis indicates intensity of propidium iodide staining. The numbers in boxes indicate the percentages of live cells in each phase of the cell cycle. The percent of total particles counted that are sub-G1 in size are also indicated.

Figure 5

MDA-MB-231 cells, grown in 6-well plates, were treated with FC101 (0–1 μM) for 24 h, followed by western blotting with antibodies to cleaved caspase-3, cleaved caspase 8, and cleaved PARP. Beta-tubulin was used for loading control. Immunoblots shown are representative of three independent experiments that showed similar results.

Figure 6

MDA-MB-231 cells, grown in 6-well plates, were treated with FC101 (0–1 μM) for 24 h, followed by western blotting with antibodies to anti-apoptotic proteins (Bcl-2, Bcl-XL, Mcl-1) and pro-apoptotic proteins (BAD, BAK, BAX). Beta-tubulin was used for loading control. Immunoblots shown are representative of three independent experiments that showed similar results.

Figure 7

HeLa cells, grown in 6-well plates, were treated with FC101 (0–1 μM) for 72 h, followed by western blotting with antibodies for p-4E-BP1 (Thr37/Thr46) phospho-Erk1/2 (Thr202/Tyr204), p38, phospho-p38 (Thr180/Tyr182). Beta-tubulin was used for loading control. Immunoblots shown are representative of three independent experiments that showed similar results.

Figure 8

The growth inhibitory effect of FC101 on the MCF-7 and MDR MCF-7/Dox cells.

Figure 9

Immunocompromised mice (SCID) were injected subcutaneously with 1x10 ⁶ SRB12-p9 cells on day 0, and injected intraperitoneally with 8 mg/kg/day FC101 dissolved in PBS, or PBS alone as a control. The tumor volumes were determined by caliper measurement on the days indicated.

Figure 10

Suppression of VEGF-induced proliferation of mouse microvascular endothelial cells (MS1).