Cucurbitacin B has a potent antiproliferative effect on breast cancer cells in vitro and in vivo

Abstract

Cucurbitacins are a group of diverse triterpenoid substances isolated from plants with medicinal properties. One particularly potent family member is cucurbitacin B (CuB). The antiproliferative effects of CuB against human breast cancer cells were tested. Six human breast cancer cell lines were examined because they represent a diverse mix of breast cancer subtypes varying in expression of estrogen receptor (ER), Her2/neu, and p53 mutation. The antiproliferative effect of CuB were also studied in vivo. The effective dose inhibiting 50% growth (ED 50 ) was between 10 -8 M and 10 -7 M for this collection of breast cancer cell lines. These cells underwent rapid morphologic changes after 15-20 min exposure to CuB (5´10 -7 M), which was associated with disruption of the microtubules and F-actin, as observed by confocal microscopy. C ucurbitacins were originally isolated from Cucurbitaceae plants. They are a group of diverse triterpenoid molecules containing a cucurbitane skeleton characterized by a 19-(10→9β)-abeo-10α-lanost-5-ene (Fig. 1).(1) They have been reported to possess a broad range of biological effects such as chemoprevention and hepatoprotection, as well as anti-inflammatory, antimicrobial and antitumor activities.(2-10) Cucurbitacins have been reported to inhibit several types of cancers including those originating in the prostate, (9) lung and breast (11) as well as choriocarcinoma.(12) Among the various cucurbitacins, the most abundant is cucurbitacin B (CuB) and its analog dihydrocucurbitacin B.(13) Our preliminary data suggest that CuB is one of the most potent compounds in this family.Breast cancer afflicts about one in nine women, with approximately 43 000 deaths per year in the USA from this disease. Although great progress has been made in both controlling the disease and preventing recurrence, additional novel therapies are needed leading us to focus on investigating the effects of CuB on breast cancer in vitro and in vivo. Materials and Methods Cells and compounds. MCF-7, MDA-MB-231, MDA-MB-453, T47D, BT474, SK-BR-3 and ZR-75-1 cells (American TypeCulture Collection, Manassas, VA, USA) were maintained at 37°C in 5% CO 2 in Roswell Park Memorial Institute media (RPMI)-1640 (Invitrogen, Carlsbad, CA, USA) with 10% fetal bovine serum (FBS; Invitrogen), 10 U/mL penicillin and 10 mg/ mL streptomycin (Invitrogen). CuB was kindly provided by CK Life Sciences International Inc., Hong Kong.Cytoskeletal staining for b-tubulin and F-actin. After incubation with CuB, culture media were removed and cells were fixed in 4% paraformaldehyde/phosphate-buffered saline (PBS), permeabilized with 0.1% Triton X-100 in PBS, and incubated with fluorescein isothyanate (FITC)-conjugated antiβ-tubulin antibody (Sigma Chemical, St. Louis, MO, USA) and/or rhodaminephalloidin (Invitrogen) to detect filamentous (F)-actin. Confocal images were collected on a Leica microscope (Leica Microsystems, Wetzlar, Germany).Animal experiments. MDA-MB-231 (1 × 10 6 ) breast cancer cells were resuspended in 100-μL matrigel and were inocul...

Cucurbitacin B inhibits growth, arrests the cell cycle, and potentiates antiproliferative efficacy of cisplatin in cutaneous squamous cell carcinoma cell lines

“…2A). These CSCC cells could recover to their normal morphology, if after 60 min of CuB exposure the cells were washed free of the drug and cultured for an additional 24 h. This is similar to morphologic changes noted in glioma, pancreatic and breast cancer cells (14,15,18). Our pulse-exposure experiments showed that a 24-h exposure to CuB (10 -7 M) largely inhibited growth of CSCC cells, while a shorter (2 or 9 h) exposure did not produce much growth inhibition.…”

“…Previous studies from our group demonstrated CuB can disrupt F-actins and microtubules in glioma, leukemia, as well as breast cancer cells (15,16,18). Given that the F-actin and the microtubule cytoskeleton is a key component involved in cell migration, we tested the ability of CuB to affect cell migration and found that CuB inhibited migration of CSCC cells.…”

“…In modern medicine, its anti-proliferative potential is of particular interest, which have been studied in leukemia and a variety of solid tumors (10,12,(14)(15)(16)18). In this study, we examined for the first time the anti-proliferative effect of CuB against CSCC cell lines.…”

Cucurbitacin B inhibits cell proliferation and induces apoptosis in human osteosarcoma cells via modulation of the JAK2/STAT3 and MAPK pathways

“…Previous studies have demonstrated the antitumor activities of cucurbitacin B in various human cancer cell lines and tumor xenografts (49,50). However, the mechanisms underlying the anticancer activities are yet to be elucidated.…”

In vitroandin vivoanticancer properties of cucurbitacin isolated fromCayaponia racemosa

“…Jayaprakasam and co-workers demonstrated the cytotoxic properties of cucurbitacins B, D, E and I, isolated from the fruits of Cucurbita andreana, against colon, breast, lung and central nervous system cancer cell lines (Jayaprakasam et al, 2003). Among this class of compounds, cucurbitacin B is the most studied, and while several studies demonstrated its efficacy in different models of cancer, including in vivo tumor xenografts (Liu et al, 2008;Wakimoto et al, 2008;Zhang et al, 2009;Chan et al, 2010), there is disagreement regarding the mechanisms underlying its anticancer activity. Suppression of the oncogene STAT 3 (signal transducer and activator of transcription 3) appears to be related to tumor inhibition (Zhang et al, 2004;Chan et al, 2010b), which does not exclude alternative mechanisms (Yasuda et al, 2010).…”