Can Hepsin Be Mutated to Prevent the Growth of Prostate Cancer Cells?

[deleted-290678]

Hello Science Buddies,

Every year, my high school hosts an annual science fair competition and this year, I submitted my project on "Redesigning the Amino Acid Sequence of the Transmembrane Protease Serine"; a surface protein responsible for performing proteolysis on the H5N1 Avian Influenza. Although I won "Best in Category" for my research project; I want to further this concept into a more important field: Cancer Research. Here's my idea: since Hepsin is also a transmembrane protease serine found in the human body, and is said to aid substantial growth in prostate cancer cells or any cancer like it, why not redesign the amino acid sequence of Hepsin, so that it could theoretically abolish its proteolysis function and stop the further growth of prostate cells? Also, couldn't this mutated Hepsin be injected into a patient via vaccine to test whether or not the theory worked?

Thank you

[deleted-291782]

Hello and thank you for your question,

In order to test this, you would have to test the re-designed protein in a cell model without the endogenous protein to see what effect this has (both with cancer and non-cancerous cells of the tissue type of interest). Ablating the proteolytic function of this protein may not have much effect on non-cancerous cells, but it could also have a very detrimental effect. What is your idea on how to test this hypothesis?

Additionally, you could introduce a mutated gene into a patient (such as with cDNA, for example), but it would have to be expressed at sufficiently high levels in the tissue of interest. I'm sure it can be done, but there may also be problems with maintaining enough of the mutated protein for a time period long enough to greatly affect cancer cell growth.

Let us know how you want to proceed.

Best,
Pharma

[deleted-290678]

Thank you for your response.
Basically, my hypothesis was that if I change the amino acid sequence of the Hepsin gene (like actually have the gene in a lab and mutate the amino acid sequence at a specific nucleotide), then it could possibly change its functions. I still don't have a concise idea of what to do right now on this because I'm still working on my idea. Also, how would ablating the proteolytic function of this protein have a very detrimental effect? And how will my mutated gene be expressed in sufficiently high levels? What areas of tissue would you suggest testing it on, like epithelial cells ?

[deleted-332001]

Hi NovaStar15! This is a very interesting topic! There are a few things to consider when trying to develop something that will mutate or inhibit this protein:
First: Which tissues express this protein? Is it specific to the prostate? The more specific it is, the less likely it will have off-target effects.
Second: Is it expressed on the plasma membrane? Since hepsin is expressed on the plasma membrane, a vaccine would be possible (only if hepsin is specific to the prostate though). Expression on the plasma membrane also makes it easier for inhibitors to recognize the protein.
Third: Feasibility. The easiest approaches would be vaccine or inhibitor. A vaccine would only be feasible if hepsin is specific to the prostate because it would otherwise produce an autoimmune disorder. The inhibitor approach is probably the most common. There are inhibitor libraries that can be used to test against a cell culture that expresses hepsin. If the activity of hepsin is reduced, you may have an inhibitor for use in a drug.

I hope this helps!
Jen

[deleted-141593]

Hi NovaStar,

I saw your message in our old thread regarding last year's project. Jen and PharmaMan have given you some good advice. Please post in this thread for continued advice. Let us know how your ideas are evolving based on what they have told you.

Cheers,
Colin

[deleted-290678]

Hi Jen!

Thanks for your response, it was very helpful! For the vaccine idea, has there ever been a vaccine for the hepsin protein? Also, what exactly is an inhibitor library?

[deleted-141593]

Hi Novastar,

Other people have thought hepsin might be a good target for immunotherapy for prostate cancer, but the results are very preliminary, you came up with a good idea! See paper here: http://onlinelibrary.wiley.com/doi/10.1 ... D80.f04t03

An inhibitor library is simply a collection of a bunch of compounds that might be biologically interesting. Researchers then treat the cells/systems of interest with hese compounds and see if one or more does something in their system. This is called "screening".

See here for such studies on hepsin

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2659609/

https://www.fredhutch.org/en/news/spotl ... tasis.html

Cheers,
Colin

[deleted-290678]

Hello,

So far, I have not found any articles on whether or not Hepsin is specific to prostate cancer cells or its growth, but I am emailing other scientists who might be able to know. However, there is another gene, PCGEM1, a prostate-specific gene that is overly expressed in prostate cancer cells just like Hepsin.
http://www.ncbi.nlm.nih.gov/gene/64002
http://www.pnas.org/content/97/22/12216.full
http://www.nature.com/onc/journal/v23/n ... 7069a.html

Also, there seems to be no vaccine for this gene, but is it possible since it's prostate cancer specific?

Thank you,
NovaStar15

[deleted-141593]

Hepsin is not prostate cancer specific, but it does seem to be present at a higher level than normal in prostate cancer: http://www.ncbi.nlm.nih.gov/pubmed/11479199

It's a pretty good target from what we know now.

Also, the fact that noone has tried to make a vaccine against PCGEM1 is not that surprising. There are many cancer therapy candidates to evaluate and test.

I did find one paper that suggests that while PCGEM1 is associated with prostate cancer, it does not appear to be linked to patient prognosis or cancer progression. This indicates that it might not be a good target: http://www.ncbi.nlm.nih.gov/pubmed/24727738

Cheers,
Colin

[deleted-290678]

So it is a better idea to stick with the Hepsin protease, and think of a way to make a vaccine against it?
Is the Recombinant/Purified Protein Vaccine a good method?

The vaccine seems like a good idea, but one of the earlier posts said that the vaccine would only be feasible if hepsin is specific to the prostate because it would otherwise produce an autoimmune disorder.

Thanks

[deleted-141593]

Up to you depending on what you find in your research on the matter. This is a complicated matter and the subject of much ongoing research.
Papers on targets for immunotherapy in prostate cancer:
http://www.hindawi.com/journals/bmri/2014/981434/
http://journal.frontiersin.org/article/ ... 00191/full

This paper has information on where hepsin is normally expressed: http://cancerres.aacrjournals.org/conte ... /3611.long

To help you out, from this paper: http://onlinelibrary.wiley.com/enhanced ... sji.12083/

The researchers made T cells that were specific for epitodes of hepsin. This is like bypassing the vaccine to get straight to the killer T cells that you want to vaccine to induce. The researcher found that

Hepsin is expressed in the normal liver and at lower levels in the kidneys, pancreas and testes [33]. Therefore, hepsin targeting for immunotherapy may have side effects in normal tissues. CTLs that were induced by hepsin-specific peptides were also used to lyse normal liver cells to investigate the effect of hepsin-specific CTLs on liver cells. The results demonstrated that hepsin-specific CTLs induced by peptides did not lyse normal liver cells in vitro (Fig. 5C).

So, this is potentially good news for you too. The hepsin-specific CTLS (Cytotoxic T lymphocytes) did not kill normal liver cells, and the liver appears to be the tissue in which normal hepsin expression is highest.

It's difficult to know if the vaccine will have side effects without first testing it in animals. Also, during human trials, some level of autoimmunity can be deemed acceptable depending upon the severity of the autoimmune symptoms, how effective the immunotherapy is, and the severity of the cancer. In other words, with a severe cancer that is not responding to other treatments, some autoimmune side effects can be acceptable to the doctor and patient if the treatment leads to meaningful improvements in patient quality of life and/or survival time. It's not a simple calculation.

Here is an interview with some cancer immunotherapy experts that might give you some perspective on this issue: http://www.medscape.org/viewarticle/570642

Cheers,
Colin

[deleted-290678]

Hi,

Upon thinking about this research, I've realized that it is way too advanced for my grade level and that I can't possibly get university lab help (sadly, I am not a PhD student), so I was thinking that I should reduce the complexity of this project and perform something that is more feasible in a high school lab. In a new thread, I've posted a question on whether or not it's possible to use fetal pigs as an answer to cancer prevention in humans (since their bodily functions are very similar to ours)?

Thank you,
NovaStar15