Science Buddies: "Ask an Expert"

Hi all,
Thank you in advance for taking time to look into my project, pretty much I want to know if using PGE2 or Prostaglandin E2 assays are a viable way of early detection of cancer in a human body. I have been doing some research and PGE2 is overproduced by cancer cells as it expands. If PGE2 assays are a viable way to find cancer I was wondering what would be a experiment to try and prove it which preferably does not use humans and animals . Any advice from experts would be well appreciated.
Thanks,
Joel

Hi there,

It's great that you've done some background research and found that PGE2 is overproduced by cancer cells as it expands. I'm not a cancer biologist, so I not 100% sure if PGE2 would be a good marker for early detection of cancer. What is the question and hypothesis you want to answer? Do you know if PGE2 is overproduced by all types of cancer cells, or if it's only produced by certain cancers? Because if PGE2 is only produced by certain cancers, these PGE2 assays should theoretically be useful in the context of those cancers. I would also find it hard to do this assay without using an animal model, but I could be wrong, so if any experts know better, please chime in. With in vitro cell culture models, typically people using either cancerous cell lines or primary cells isolated from living tissue and then grown in vitro. The reason why cancerous cell lines are used for a lot of cell culture work is because primary cells cannot be passaged for the long term, so for people who want to have a cell line that they can continuously passage to do lots of experiments, they have to genetically alter these cells in such a manner that they will proliferate infinitely (i.e. they become cancer-like). If you want to use primary cells, they aren't cancerous, so theoretically, they shouldn't be overproducing PGE2 according to what you had found. If you use cancer cell lines, they would already be cancerous so that doesn't address your "early detection of cancer" question. To get at your question, I would think that the best way would be to induce tumorigenesis in an animal model and then measure the PGE2 levels in the serum/blood overtime to see if there is an increase in the levels overtime, and if this could be detected in the early stages of tumor formation. Other experts, does this sound reasonable to you? However, I am ultimately not an expert in cancers so if anybody else has better advice, please share.

Hope that helps,
Connie

Hi Joel,

You have a good idea in wanting to look for a marker for early detection of cancer, but I'm afraid PGE2 is not a good candidate. Prostaglandins such as PGE2 are up-regulated in nearly all inflammatory conditions and that includes asthma, arthritis, diabetes, heart disease and infections as well as cancer. So, as a marker, PGE2 is not specific for cancer.

The problem of early detection has plagued scientists and doctors for decades and we still do not have a set of markers with both high sensitivity and specificity. There are a few like prostate-specific antigen or the M2-PK for colon cancer that work pretty well, but most are still too prone to false positives or false negatives to be reliable.

If you do want to do a project on cancer detection, then as Connie suggested you can do experiments with human cell lines provided you can find a lab to work in. You can grow cancer cells in petri dishes and also normal cells for comparison and test them for expressing certain proteins or having certain genetic markers. To compare normal with tumor cells you would need to have access to some fairly complex and expensive equipment.

Think about what questions you could ask with the resources that you have available and we will try to help you create a workable hypothesis and some interesting experiments.

Best wishes,

Sybee