1. Selective Growth Inhibition of
Carotenoids in Prostate Cancer
Texas Tech University HSC El Paso, Student Intern
Mentor: Dr. Xiaoming Gong
Joel Quinones
2. Epidemiology – Prostate Cancer
Prostate cancer is the second most common cause
of cancer-related death among men in the USA.
In 2015, the National Cancer Institute estimates:
220,800 new cases of prostate cancer
27,540 deaths from prostate cancer
The prostate is a gland which produces a
fluid that protects sperm
Figure 1: Prostate cancer
statistics
Figure 2: Prostate cancer illustration
3. Carotenoids and Prostate Cancer
Carotenoids are pigments found
in plants, and bacteria.
~700 carotenoids have been
characterized. 25-30
carotenoids are commonly
found in human diets.
They have polyisoprenoid
structures and are lipophilic.
Dietary carotenoid intake,
specifically lycopene, is inversely
associated with prostate cancer
risk.
Figure 3: Carotenoids structures
5. Figure 6: Prostatic Tissue Samples (Western Blot)
Cancers BPH Normal Tissues +
BCO2
β-actin
BCO2 Expression in Human Normal and
Cancerous Prostate Tissue
Lindqvist et al. J Histochem Cytochem. 2005
Gong et al. PLoS ONE. in press
Figure 5: BCO2 immunohistochemistry
– prostatic epithelium (and stroma?)
6. Hypothesis
Carotenoids impair mitochondrial function in cancer cells through
inducing excessive Reactive Oxygen Species (ROS), resulting in
cancer cell death.
Mitochondrial BCO2 degrades carotenoids to protect mitochondria
from carotenoid-induced dysfunction.
Figure 7: Working model of selective cancer cell killing through carotenoid-induced ROS
8. Methods: MTT Assay and Flow
Cytometry
MTT Assay: colorimetric assay for cell number
Plating cells on a 96-well plate
Treating the cells
MTT procedure followed by absorbance at 570 nm
Flow Cytometry: cell counting and
ROS detection by laser
Plate cells in a 6-well plate
Treat cells with carotenoids
Data are analyzed in a flow cytometer
Figure 8: 96-well culture
plate
9. Lutein inhibits growth of prostate cancer
cells but not normal prostatic epithelial cells
Figure 9: MTT assay; conc.-dependent lutein effects on cell growth
P<0.05
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10. Lutein Epoxide has inhibitory effect on
prostate cancer cells
Figure 10: MTT assay; lutein epoxide effects on prostate cancer cells
P<0.05
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11. P<0.05
Lycopene inhibits growth of prostate cancer
cells but not normal prostatic epithelial cells
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Figure 11: MTT assay; conc.-dependent lycopene effects on cell growth
12. Beta-Carotene has no significant effect on
normal or prostate cancer cells
Figure 12: Beta-Carotene effects on Prostate Cell lines
13. Effects of Lutein ± Chemotherapeutic Agent
(Paclitaxel, Px) on Prostate Cancer Cells
Figure 13: Lutein and taxane (Px) effects on PC-3 cells
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P<0.05
14. Effects of Lutein on Intracellular ROS
Production in Prostate Cancer Cells
Figure 14: ROS in DU145 and PC-3
15. Conclusions and Future Directions:
Summary:
Lutein and lycopene, but not β-carotene, inhibit
prostate cancer cell growth.
There is little apparent reduction in cell viability of
PrECs treated with different carotenoids.
Lutein enhances the suppressive effect of a common
chemotherapeutic agent, paclitaxel.
Lutein increases intracellular ROS production in
prostate cancer DU145 cells
These are the first data to show anticancer effects of
lutein, previously recognized principally for its effects
in eye and brain health.
Future Directions:
Investigate the molecular mechanisms of carotenoid
action in prostate cancer.
16. Acknowledgments
SABR program
Dr. Raj, Jazmine, Valerie
Dr. Xiaoming Gong
Dr. Lewis P. Rubin
Norberto Posecion
Haley Swanson, Geoffrey Allison,
Christian Draper, Joshua Smith
Hello everyone my name is Joel Quinones.
My mentor is Dr. Gong.
And today I will be talking about “Selective Growth Inhibition of Carotenoids in Prostate Cancer.”
First I want to start with the Epidemiology of Prostate Cancer.
Prostate Cancer is the most second most common type of cancer in American men.
In 2015 the National Cancer Institute estimates about 220,000 new prostate cancer and from those cases is estimated 27,000 deaths.
Prostate is a gland located below the bladder as illustrated by the picture, it produces a fluid which protects the sperm.
The graph to the right illustrates how about 1 out of 10 cancer cases in the US is a prostate cancer.
Now I want to talk about Carotenoids and Prostate Cancer.
Carotenoids are pigments found in plants.
700 carotenoids have been characterized, but only 25-30 carotenoids are commonly found in human diet
They have a polyisoprenoid structure, which is this one, and they have a lipophilic character which means they are fat soluble.
Dietary carotenoids like lycopene are inversely associated with prostate cancer risk, which means the more carotenoid consumption the less likely you are to get prostate cancer.
To the right we have the structure of different carotenoids, Beta-carotene found in carrots, Lutein found in egg yolk, and lycopene found in tomates.
How are this Carotenoids metabolized?
Carotenoids are metabolized by carotenoid cleavage enzymes. Two enzymes are found in human, Beta-carotene 15,15’-monooxygenase BCO1 and Beta-carotene 9’,10’-dioxygenase BCO2.
BCO1 is located in the cytosol and cleaves beta-carotene at 15 and 15’ double bound to form two molecule of Vitamin A. BCO2 is located in the mitochondria and cleaves carotenoids at the 9’ and 10’ double bond, to produce apocartenals.
What is significant about BCO2?
BCO2 is expressed in normal prostate tissues. But its expression is deceased or lost in prostate cancer tissues.
This background knowledge lead us to our hypothesis.
The first part of our hypothesis is “Carotenoids impair mitochondrial function only in cancer cells through inducing excessive Reactive Oxygen Species (ROS), resulting in cancer cell death.”
The second part of our hypothesis states “Mitochondrial BCOS degrades carotenoids to protect mitochondria from carotenoid-induced dysfunction.”
From the picture we can see that on a Normal Cell there is BCO2 expression, when the carotenoid enters the mitochondria it is degraded by BCO2 leading to apocartenals which are send to peroxisome.
In a cancer sell there is almost no expression of BCO2, when carotenoids enter the mitochondria they create ROS, once again reactive oxygen species, and induce apoptosis.
In order to test our hypothesis we formulated methods.
The carotenoids we treated with are Lutein, Lutein Epoxide, Lycopene, and Beta-carotene.
The cell lines we use to test the carotenoids are PC-3 and DU145 which are late stage cancer, and PrEC which is normal prostate epithelial cells.
The methods used to acquire our data are MTT Assay and Flow Cytometry.
MTT Assay is a colorimetric assay for cell viability AND NUMBER. We plated cells, treated the cells then did an MTT Assay.
Flow cytometry is a cell counter and biomarker detector by laser. We plated cells, treated then performed flow cytometry.
The data obtained is as followed:
On the y-axis we have percentage of cell viability and on the x-axis we have concentration of the carotenoid.
The data shows that lutein inhibited prostate cancer cells, but not normal prostate epithelial cells.
We also tested effect of Lutein Epoxide on prostate cancer cells. As you can see, Lutein Epoxide inhibits both PC-3 and DU145 cell growth and is more effective towards DU145.
Lycopene also showed inhibitory effect on the growth of prostate cancer cells but not normal prostate cells. Lycopene seems more effective towards PC-3.
The data for Beta-carotene showed how it had no cell viability effect on any cells.
What happens when a carotenoid is combined with a chemotherapy drug like paclitaxel?
The data shows that there is a significant effect of Lutein and Paclitaxel by themselves, but when they are combined the effects are enhanced. Paclitaxel plus lutein has a significant greater effect on cell viability from lutein alone or paclitaxel alone.
As we hypothesized that carotenoids induced intracellular ROS production upon BCO2 expression, we measured ROS production in DU145 and PC-3 cells under treatmernt of luterin. On this data we have cell count on the y axis and ROS on the x-axis.
From the first picture shows the endogenous ROS, PC-3 cells have higher ROS production than that of DU145. lutein induces ROS production only in DU145 cells but not PC-3 cells.
From the data we can conclude:
Lutein and Lycopene inhibit prostate cancer growth unlike Beta-Carotene
There is little apparent reduction of PrEC with the different carotenoids tested.
Lutein enhances the suppressive effect of paclitaxel.
Lutein increases ROS production of DU145.
This is the first date showing lutein with anticancer effects. Previous data shows it helps with eye and brain health.
For future experiments, it is planned to investigate the molecular mechanism of carotenoids.
I want to thank the SABR program.
Dr. Raj, Jazmine, Valerie
My mentor Dr. Gong
Dr. Rubin
Norberto
And everyone in my lab
Thank you
