licenses/by-nc-nd/3.0/). Reproduction is permitted for personal, noncommercial use, provided that the article is in whole, unmodified, and properly cited. Received: 2014.03.17; Accepted: 2014.05.23; Published: 2014.07.02 Background: Consumption of lycopene through tomato products has been suggested to reduce the risk of prostate cancer. Cellular adhesion and migration are important features of cancer progression and therefore a potential target for cancer interception. In the present study we have examined the in vitro effect of lycopene on these processes. Methods: Prostate cancer cell lines PC3, DU145 and immortalised normal prostate cell line PNT-2 were used. The adhesion assay consisted of seeding pre-treated cells onto Matrigel™, gently removing non-adherent cells and quantitating the adherent fraction using WST-1. Migratory potential was assessed using ibidi ™ migration chamber inserts, in which a cell-free zone between two confluent areas was allowed to populate over time and the migration measured. Results: 24 hour incubation of prostate cell lines with 1.15µmol/l lycopene showed a 40 % re-duction of cellular motility in case of PC3 cells, 58 % in DU145 cells and no effect was observed for PNT2 cells. A dose related inhibition of cell adhesion to a basement membrane in the form o

Chopra, Mridula

Cooper, Alan

Elgass, Simone

International Journal of Medical Sciences

English

PubMed

Simone Elgass

Alan Cooper

Mridula Chopra

Crossref

Lycopene Treatment of Prostate Cancer Cell Lines Inhibits Adhesion and Migration Properties of the Cells

CiteSeerX

Portsmouth University Research Portal (Pure)

Int. J. Med. Sci. 2014, Vol. 11 
 
 
http://www.medsci.org 
948 
International Journal of Medical Sciences 
2014; 11(9): 948-954. doi: 10.7150/ijms.9137 
Short Research Communication 
Lycopene Treatment of Prostate Cancer Cell Lines 
Inhibits Adhesion and Migration Properties of the Cells 
Simone Elgass, Alan Cooper and Mridula Chopra  
School of Pharmacy and Biomedical Sciences, IBBS, University of Portsmouth, Portsmouth, UK  
 Corresponding author: Dr Mridula Chopra, School of Pharmacy and Biomedical Sciences, St Michael’s Building, White Swan Road, 
University of Portsmouth, Portsmouth PO1 2DT. Tel: 02392842796; Fax: 02392843565; Email: Mridula.Chopra@port.ac.uk 
© Ivyspring International Publisher. This is an open-access article distributed under the terms of the Creative Commons License (http://creativecommons.org/ 
licenses/by-nc-nd/3.0/). Reproduction is permitted for personal, noncommercial use, provided that the article is in whole, unmodified, and properly cited. 
Received: 2014.03.17; Accepted: 2014.05.23; Published: 2014.07.02 
Abstract 
Background: Consumption of lycopene through tomato products has been suggested to reduce 
the risk of prostate cancer. Cellular adhesion and migration are important features of cancer 
progression and therefore a potential target for cancer interception. In the present study we have 
examined the in vitro effect of lycopene on these processes. 
Methods: Prostate cancer cell lines PC3, DU145 and immortalised normal prostate cell line 
PNT-2 were used. The adhesion assay consisted of seeding pre-treated cells onto Matrigel™, 
gently removing non-adherent cells and quantitating the adherent fraction using WST-1. Migratory 
potential was assessed using ibidi™ migration chamber inserts, in which a cell-free zone between 
two confluent areas was allowed to populate over time and the migration measured.  
Results: 24 hour incubation of prostate cell lines with 1.15µmol/l lycopene showed a 40% re-
duction of cellular motility in case of PC3 cells, 58% in DU145 cells and no effect was observed for 
PNT2 cells. A dose related inhibition of cell adhesion to a basement membrane in the form of 
Matrigel™ was observed in all three cell lines and it reached statistical significance for PC3 and 
PNT2 cells at lycopene concentrations ≥1.15µmol/l. However, in case of DU145, only a con-
centration of 2.3µmol/l showed a significant reduction.  
Conclusion: This in vitro investigation indicates that lycopene can influence the cell adhesion and 
migration properties of cancer cells at a dose which is arguably achievable in patients. The results 
of our study expand our understanding of a chemo preventive role of lycopene in prostate cancer. 
Key words: lycopene, prostate cancer, cell adhesion 
Introduction 
Prostate cancer is the most common male cancer 
in the Western society. Although genetic predisposi-
tion is an important contributing factor, diet and life-
style are suggested to play a significant role, espe-
cially in sporadic cancer [1]. The cancer preventive 
role of tomatoes was first highlighted by a large epi-
demiological study in 1995, suggesting them as a 
strong dietary predictor of reduced prostate cancer 
risk [2] and attributing their protective effect to lyco-
pene. Several modes of action have been proposed for 
this effect (see review by Karin Wertz for further details) 
[3]. These include its ability to inhibit prostate cancer 
cell proliferation, alteration of cell cycle progression, 
inhibition of androgen activation and signalling, im-
proved gap-junction communications, inhibition of 
IGF-1 and anti-angiogenic activity [4]. Adhesion to 
extracellular matrix (ECM) and motility of tumour 
cells within the ECM are important steps in the inva-
sion progress of metastatic tumour cells.. Previous 
studies have shown an inhibitory effect of lycopene in 
SK Hep-1 hepatoma cells, however the concentrations 
used were much higher than can be achieved in vivo 
[5,6]. Lycopene’s effect on the adhesion and migration 
properties of prostate cancer cells has not been re-
ported before. 
In the present study, physiologically relevant 
 
Ivyspring  
International Publisher 
Int. J. Med. Sci. 2014, Vol. 11 
 
http://www.medsci.org 
949 
concentrations of lycopene were tested for their effects 
on the migratory and adhesion properties of prostate 
cancer cell lines.  
Methods 
PC3 (ECACC) and DU145 (ATCC) prostate can-
cer cell lines, both androgen independent and exhib-
iting metastatic properties in vivo, were investigated. 
The immortalised normal prostate epithelial cell line 
PNT2 (ECACC) was also used. An all-E >95% pure 
isomer of synthetic lycopene (DSM, Nutritionals) was 
tested. Crystalline lycopene was dissolved in tetra-
hydrofuran (THF) containing 0.025% butylated hy-
droxytoluene. The final solvent concentration was 
kept constant across all treatments (including con-
trols) at a concentration of 0.1%, chosen as having a 
minimal effect on cell viability.  
Cell Adhesion Assay 
Cells were grown in T25 cell culture flasks to 
~60% confluence, when lycopene was applied at 0, 
0.58, 1.15 and 2.3 µmol/L in serum free medium. 
Flasks were incubated for 24 hour in 5% CO2 at 37°C. 
Following treatment, cells were washed 2x with PBS 
and detached using 3ml EDTA (0.02%). They were 
suspended in fresh culture medium at a concentration 
of 5x 104 cells/ml and 0.1ml seeded into MatrigelTM 
(BD Biosciences) coated wells of 96-well plates. After 1 
hour incubation at 37°C, all wells were gently washed 
three times with PBS to remove unattached cells. The 
remaining adherent cells were left to settle for 18h in 
serum free medium, at which time they were exposed 
to WST-1 reagent (Roche, Applied Science) as per 
manufacturer’s specification for spectrophotometric 
assessment of cell numbers. The adhesion assays were 
carried out in triplicate for each of the cell lines on 
three different days and the effects of lycopene dose 
are presented relative to untreated controls showing 
means of three independent experiments. 
Migration Assay 
For the migration assay, ibidi™ culture inserts 
(Thistle Scientific Ltd, UK) were used. Briefly, the 
inserts consist of two chambers separated by a 0.5mm 
divider, each chamber with a growth area of 0.22cm2. 
The inserts were planted into 35mm tissue culture 
dishes using sterile tweezers. Cell suspensions were 
prepared at 7-9x105 cells/ml in medium, of which 
70µl was transferred to each chamber. The cells were 
left to adhere and grow to ~90% confluence. They 
were then exposed to 0, 0.58, 1.15 and 2.30µmol/L 
lycopene within the chambers for 24h, at which time 
the cells were 100% confluent, as required for the mi-
gration assay. At this stage, cells were arrested by 
addition of 10µg/L mitomycin-C for 30 minutes to 
prevent further proliferation. In the case of the normal 
PNT2 cell line, cells treated with 10µg/l mitomycin-C 
had migrated at a much slower rate than the PC3 cells. 
This was partly due to a loss in viability resulting 
from the cell-cycle arrest induced by the mitomycin-C 
and the dose applied to PNT2 cells was subsequently 
reduced from 10µg/l to 2µg/l. However, since a con-
centration of 2µg/l did not appear to have a signifi-
cant inhibitory effect on the proliferation of DU145 
and PC3 prostate cancer cell lines, a mitomycin-C 
concentration of 10µg/l was used for these cell lines. 
 The dividing strip between the chambers was 
removed and images were acquired along the cell-free 
zone between time 0 and 24 hours. Cell migration was 
assessed using AngioSys V1.0 software (TCS Cell-
works), measuring the area covered by the cells. The 
encroachment of the cell-free gap for each treatment 
was determined by comparing results to the 0h time 
point. Experiments for each cell line were performed 
in triplicate. 
Statistical Analysis 
Pairwise comparisons were done using SPSS 
(PASW18) to test the difference between control and 
the lycopene treated cells and differences at a level of 
0.05 deemed significant.  
Results 
The Effect of Lycopene on Cell Adhesion 
Figure 1 shows the cell adhesion data for PC3, 
DU145 and PNT2, obtained using the WST-1 assay. 
Experiments for each cell line were carried out in 
triplicate on three different days and data points pre-
sented are means of the three independent experi-
ments (i.e. average of 9 measurements) ± SD. 
 
Figure 1: Effect of Lycopene on prostate cell adhesion to MatrigelTM. PC3, 
PNT2 and DU145 cell-lines were pretreated with lycopene for 24h and 
then seeded into 96-well Plates precoated with MatrigelTM. The number of 
adhering cells was determined by WST Assay. The data points are pre-
sented as Means ± SD of three separate experiments. The asterisk (*) 
denotes significant difference from the untreated Control (P<0.05). Dou-
ble asterisk (**) indicates that this data point is also significantly different 
from the other treatment concentrations. 
Int. J. Med. Sci. 2014, Vol. 11 
 
http://www.medsci.org 
950 
At 2.3µmol/l, lycopene significantly reduced the 
attachment of all prostate cell lines to Matrigel™ 
(Figure 1). A significant inhibition of adhesion was 
also observed in PC3 cells at a lycopene concentration 
≥1.15µmol/l (P <0.05); however, it failed to reach sta-
tistical significance in the DU145 cell line. Lycopene 
also inhibited the adhesion of PNT2 cells, but the ef-
fect was the same at all lycopene concentrations and 
magnitude was lower.  
The Effect of Lycopene in the Cell Migration 
Assay 
There was a significant reduction in cellular mi-
gration of PC3 prostate cancer cells, both at 1.15 and 
2.3µmol/l lycopene (Figure 2a). The degree of inhibi-
tion was similar at lycopene concentrations of 1.15 
and 2.3µmol/l. Treatment of DU145 cells with lyco-
pene resulted in a more pronounced inhibition of mi-
gration compared to PC3 cells (Figure 2b). In contrast, 
compared to the cancer cell lines, PNT2 cells migrated 
faster as shown by the merging of cell sheets within 
24h even in the presence of 1.15 µmol/L lycopene 
(Figure 2c and d). However, at a higher concentration 
there was some inhibition of migration in the presence 
of lycopene though magnitude was lower than the 
cancer cell lines. 
Int. J. Med. Sci. 2014, Vol. 11 
 
http://www.medsci.org 
951 
Int. J. Med. Sci. 2014, Vol. 11 
 
http://www.medsci.org 
952 
Int. J. Med. Sci. 2014, Vol. 11 
 
http://www.medsci.org 
953 
 
Figure 2: Effect of Lycopene on migratory properties of prostate cells. Migration of (a) PC3, (b) DU145 and (c) PNT2 cells in the presence of 10µg/l 
Mitomycin-C (d) PNT2 cells in the presence of 2µg/l Mitomycin-C. Cells were grown to 80% Confluence in ibidi Culture Inserts and treated with 0, 1.15 and 
2.3µmol/l Lycopene for 24h. 10µg/l Mitomycin-C was used to arrest the cells and avoid further proliferation [in case of PNT2 cells, 2µg/l Mitomycin-C was 
used (d), since a concentration of 10µg/l Mitomycin-C was found to be toxic to the cells (c)]. The culture inserts were then removed to reveal the gap and 
pictures were taken between 0-24h. Experiments were repeated three times. 
 
Discussion 
In the present study, lycopene inhibited adhe-
sion of cancer cells to Matrigel™ as well as influenced 
the migratory properties of cancer cells at a physio-
logically relevant concentration of 1.15µmol/l. A sim-
ilar effect was shown by Hwang and Lee in SK-Hep1 
hepatocellular carcinoma cells [5]. However the ly-
copene concentration of 10µmol/l used in their study 
exceeded our maximum concentration of 2.3µmol/l 
lycopene. In our study, lycopene reduced motility 
rates of PC3 prostate cancer cells by up to 40% at 
Int. J. Med. Sci. 2014, Vol. 11 
 
http://www.medsci.org 
954 
concentrations as low as 1.15µmol/L. Lycopene 
showed maximum inhibition of adhesion in PC3 cells, 
however its anti-motility effect was more pronounced 
in DU145 with an overall inhibition of migration of 
58% and 68% at final concentrations of 1.15 and 
2.3µmol/l, respectively. To our knowledge, this is first 
study in which adhesion and migratory properties of 
aggressive prostate cancer lines have been studied at 
physiologically achievable concentrations of lyco-
pene, i.e. 1-2µmol/l. It was interesting to see that ly-
copene showed only a small effect on the adhesion 
and migration properties of the immortalised normal 
prostate epithelial cell line PNT2.  
Diagnosis as well as treatment of cancer is often 
preceded by years of cancer progression. At presenta-
tion, many patients may already have metastases. 
Identification of dietary components that can inter-
cept the process in its early stages and knowledge of 
the concentration that is likely to be effective is 
therefore valuable. In our study, lycopene at a con-
centration of 0.58µmol/l failed to affect adhesion and 
migration (results not shown) of prostate cancer cells. 
This helps explain why lycopene failed to show pro-
tective effects in cancer patients at plasma concentra-
tions of ~ 0.60µmol/l [7,8]. Lycopene demonstrated a 
significant inhibitory effect at 1.15µmol/l, though the 
effect on both adhesion and migration was more 
pronounced at a final concentration of 2.3µmol/l. This 
last concentration may be difficult to achieve in vivo, 
although one report suggests a rise in plasma lyco-
pene to 2.08µmol/l when participants consumed half 
a cup of tomato sauce daily for two weeks [9]. An 
increase in plasma concentrations to ~1.15µmol/l has 
been shown to be easily achievable in both healthy 
individuals and prostate cancer patients [10,11]. Re-
sults from our present study and a previous report [4] 
have shown that at above concentrations, lycopene 
can intercept the mechanisms important in metasta-
sis. We therefore suggest that clinical intervention 
studies in cancer patients should select a dose of ly-
copene that is likely to increase plasma lycopene lev-
els to more than 1.2 µmol/L. 
In conclusion, the present study provides in vitro 
evidence to support the previous clinical observations 
that reported lower incidence and less aggressive 
nature of prostate cancer in those who regularly con-
sumed tomato based products. Our study also sug-
gests concentrations at which biological effects of ly-
copene are likely to occur and are therefore relevant 
for further investigation into the clinical efficacy of 
this nutrient. Further studies are underway in our 
laboratory to examine the molecular pathways 
through which lycopene is likely to influence the in-
vasive properties of cancer cells. 
Acknowledgements 
The authors would like to thank DSM Nutrition 
Products limited for their generous gift of the lyco-
pene used in the present study. 
Competing Interests 
The authors have declared that no competing 
interest exists. 
References 
1. Wu K, Erdman JW, Schwartz ST, Platz EA, Leitzmann M, Clinton SK et al. 
Plasma and Dietary Carotenoids, and the Risk of Prostate Cancer: A Nested 
Case-Control Study. Cancer Epidemiol Biomarkers Prev 2004;13:260-269. 
2. Giovannucci E, Ascherio A, Rimm EB, Stampfer MJ, Colditz GA, Willett WC. 
Intake of carotenoids and retinol in relation to risk of prostate cancer. J. Natl. 
Cancer. Inst. 1995;87:1767-1776. 
3. Wertz K. Lycopene effects contributing to prostate health. Nutr Cancer 
2009;61:775-783. 
4. Elgass S, Cooper A, Chopra M. Lycopene inhibits angiogenesis in HUVECs 
and rat aortic rings. Br J Nutr 2012;108:431-439. 
5. Hwang ES, Lee HJ. Inhibitory effects of lycopene on the adhesion, invasion 
and migration of SK-Hep1 human hepatoma cells. Exp Biol Med (Maywood) 
2006;231: 322-327. 
6. Huang C-S, Shih M-K, Chuang C-H, Hu M-L. Lycopene inhibits cell migration 
and invasion and upregulates Nm23-H1 in a highly invasive hepatocarcinoma 
SK-Hep1 cells. J Nutr 2005;135:2119-2123. 
7. Puri T, Goyal S, Julka PK, Nair O, Sharma DN, Rath GK. Lycopene in treat-
ment of high-grade gliomas: a pilot study. Neurol India 2010;58(1):20-23. 
8. Kumar NB, Besterman-Dahan K, Kang L, Pow-Sang J, Xu P, Allen K et al. 
Results of a Randomized Clinical Trial of the Action of Several Doses 
of Lycopene in Localized Prostate Cancer: Administration Prior to Radical 
Prostatectomy. Clin Med Urol. 2008;1:1-14. 
9. Allen CM, Schwartz SJ, Craft NE, Giovannucci EL, De Groff VL, Clinton SK . 
Changes in plasma and oral mucosal lycopene isomer concentrations in 
healthy adults consuming standard servings of processed tomato products. 
Nutr Cancer 2003;47:48-56. 
10. Lee A, Thurnham DI, Chopra M. Consumption of tomato products with olive 
oil but not sunflower oil increases the antioxidant activity of plasma. Free Rad. 
Biol. Med. 2000;29:1051-1055. 
11. Bowen P, Chen L, Stacewicz-Sapuntzakis M, Sharifi R, Ghosh L, van Breemen 
R et al. Tomato sauce supplementation and Prostate Cancer: Lycopene accu-
mulation and modulation of biomarkers of carcinogenesis. Exp. Biol. Med. 
2002;227:886–893. 


Changes in plasma and oral mucosal lycopene isomer concentrations in healthy adults consuming standard servings of processed tomato products.

Consumption of tomato products with olive oil but not sunflower oil increases the antioxidant activity of plasma. Free Rad.

Inhibitory effects of lycopene on the adhesion, invasion and migration of SK-Hep1 human hepatoma cells. Exp Biol Med (Maywood)

Intake of carotenoids and retinol in relation to risk of prostate cancer.

Lycopene effects contributing to prostate health.

Lycopene in treatment of high-grade gliomas: a pilot study.

Lycopene inhibits angiogenesis in HUVECs and rat aortic rings.

Lycopene inhibits cell migration and invasion and upregulates Nm23-H1 in a highly invasive hepatocarcinoma SK-Hep1 cells.

Plasma and Dietary Carotenoids, and the Risk of Prostate Cancer: A Nested Case-Control Study. Cancer Epidemiol Biomarkers Prev

Results of a Randomized Clinical Trial of the Action of Several Doses of Lycopene in Localized Prostate Cancer: Administration Prior to Radical Prostatectomy. Clin Med Urol.

Tomato sauce supplementation and Prostate Cancer: Lycopene accumulation and modulation of biomarkers of carcinogenesis.

Lycopene treatment of prostate cancer cell lines inhibits adhesion and migration properties of the cells

Lycopene treatment of prostate cancer cell lines inhibits adhesion and migration properties of the cells

Abstract

Similar works

Full text

Available Versions

Crossref

CiteSeerX

Portsmouth University Research Portal (Pure)