Statins for Cancer and Autism? Another case for PTEN?

When I first started this blog and my investigation into the biology of autism, I did shy away from the more complex areas like genetics.  I assumed that this would be best left to the “experts” and be beyond the powers of those without fancy laboratory tools.

My literature review took me early on to oxidative stress and then neuroinflammation.  I deduced that in the case of neuroinflammation, it might be possible to control inflammatory cytokines using statins.  I also noted the use of statins in TBI (Traumatic Brain Injury). I thought it would be harmless to do a quick trial, not really expecting anything to happen; but it did, and from the very first dose.

The literature is full of references to lipid dysfunction in autism and one large sub-group in autism is known to have high cholesterol.  Cholesterol and inflammation are now known to go hand in hand.  When inflammation is present, the body can react by laying down a protective layer of cholesterol.  The problem is that too much cholesterol is not good for you either.  The real culprit is not the cholesterol, it is the inflammation.

If you are in the high cholesterol autism group, a cholesterol lowering drug that is also anti-inflammatory may be “just what the doctor ordered”.

Be warned that another subgroup in autism has very low cholesterol.  In a study at the Kennedy Krieger Institute, 19% of children had extremely low cholesterol, meaning lower than 99% of typical children.

Autism: New Study Discovers Statistically Significant Link Between Abnormally Low Cholesterol Levels And Autism Spectrum Disorders

There is a rare condition, leading to autism called Smith-Lemli Opitz syndrome (SLOS).  SLOS is caused by a mutation in an enzyme involved in cholesterol synthesis; the resulting biochemical characteristics may be predictable. Most patients have lowered plasma cholesterol levels.

Since cholesterol testing is cheap and widely available, you can easily determine which group you are in.

This post is for the high cholesterol cohort.

Note well how meaningless a figure for the "average cholesterol level" in autism would be. In the autism literature they frequently take the mean average for all data, thus missing the point. 

Why Statins for Autism?

My initial logic was that since inflammatory markers are often elevated in autism and that oxidative stress and inflammation are self-reinforcing, it would be logical to find an effective anti-inflammatory agent.  Steroids might fit the bill, but they cause plenty of side effects in long term use; their short term use in autism can be remarkably effective.  So I looked further, and having screened the literature, ended up convincing myself of the potential of statins.  Read all about cytokine storms in the old posts, if you are interested.

I choose  Atorvastatin (also known as Lipitor or Sortis), since it freely crosses the blood brain barrier (BBB) and is safely used my tens of millions of people around the world.

It worked.

Explaining Statin Therapy to others.

The most important thing is to have a therapy that works;  but then you have to explain it to others.

I was recently explaining it again to a doctor relative, who was asking how I could be sure it works.  I explained that every time I stop using it, within a day behaviour changes in the same predictable way.  It is as if people with autism have an inhibitory barrier; there are things they can do, want to do, but something is blocking them from doing them.

Examples are numerous.  Speech being one.  Plenty of kids with autism are non-verbal, everything is physically functional, yet they do not talk, even when they want to communicate.

At the age Monty, now aged 11 with ASD, tried the statin he was relatively verbal.  The immediate change in him was that he suddenly started to play the piano, by himself.  Odd it may sound.

In his earlier years he would often get “stuck”.  He would be upstairs and unable to come downstairs, somebody had to go up and get him.

When I now stop the statin, he will again get “stuck”.  He will stand in the kitchen and want to leave and just say “go that way”, but not move.  You have to take his hand, so that he can “go that way”.

A Better Explanation?

Now I have another explanation of why statins may be effective in one large sub-group of autism.

Statins up-regulate a known key dysfunctional autism gene, and protein, called PTEN.  I mentioned PTEN in a previous post, since one chemical released by eating broccoli also up-regulates PTEN.

Science has already shown that things that down-regulate PTEN (like seizures) make autism worse.

The full science behind PTEN will come in a later post.

Statins and Cancer

Regular readers will recall that PTEN is also a tumor suppressor gene and is therefore a target for cancer research.

Thinking the way I do, I know that statins increase PTEN and that this should slow cancer growth.  Hundreds of millions of people take statins and many millions get cancer, so what about people on statins getting cancer?

A quick check on google and there we have studies showing that people on statins get less cancer and that in common cancers like that of the prostate, the outcome is better when statins are taken.

Now this is not a cancer blog, but you do not have to dig very deep to uncover a wealth of supporting evidence.

Statins and Prostate Cancer: Novel, Encouraging Study

Postoperative statin use and risk of biochemical recurrence following radical prostatectomy: results from the Shared Equal Access Regional Cancer Hospital (SEARCH) database

Conclusion

In this retrospective cohort of men undergoing RP, post-RP statin use was significantly associated with reduced risk of BCR. Whether the association between post-RP statin use and BCR differs by race requires further study. Given these findings, coupled with other studies suggesting that statins may reduce risk of advanced prostate cancer, randomized controlled trials are warranted to formally test the hypothesis that statins slow prostate cancer progression.

Statins and prostate cancer (Harvard Medical School)

Statins could reduce the risk of breast cancer

Statins could reducethe risk of pancreatic cancer

Statin use and risk of liver cancer: an update meta-analysis

 Conclusions This meta-analysis suggests that statin is associated with a significant risk reduction of liver cancer when taken daily for cardiovascular event prevention. However, this preventive effect might be overestimated due to the exposure period, the indication and contraindication of statins and other confounders. Statins might be considered as an adjuvant in the treatment of liver cancer.

Statins and PTEN

I am no cancer expert, but I can read the literature and the evidence is pretty compelling to me.  It is not enough, however, for doctors to prescribe statins to avoid cancer.  They are so busy prescribing statins to over 50s for other reasons, it does not really matter.

We came across PPAR previously.  PPAR gamma is a pathway to treat type 2 diabetes and the old type 2 diabetes drug Pioglitazone has shown promise in an autism study.

PPAR alpha, beta and gamma in Autism, Heart Disease and Diabetes

 Effect of pioglitazone treatment on behavioral symptoms in autistic children

At that time I was more interested in PPAR-alpha, due to its role in mast cell stabilization.

It is via PPAR-gamma, that statins up regulate PTEN.

You do not want to overdo it, because at very high doses too much PPAR gamma protein will be produced and you risk causing type 2 diabetes.

Low doses of statins are trouble free for most people, but high doses are associated with increased risk of diabetes and all kinds of aches and pains.

The statin effect in autism does not increase with higher doses, only a small dose is required.

Regulation of the PTEN promoter by statins and SREBP.

Abstract

Germline mutations in the tumor-suppressor gene PTEN predispose to heritable breast cancer. The transcription factor peroxisome proliferator-activated receptor-gamma (PPARgamma) has also been implicated as a tumor suppressor pertinent to a range of neoplasias, including breast cancer. We previously demonstrated that lovastatin may signal through PPARgamma and directly upregulate PTEN expression at the transcriptional level. In our current study, we show that simvastatin, pravastatin and fluvastatin can induce PTEN expression in a dose-dependent manner. This resulted from an increase in PTEN mRNA indicating transcriptional upregulation. In addition, we observed, for the first time, that upregulation of sterol response element-binding protein (SREBP), known to induce PPARgamma expression, can increase PTEN expression. Using reporter assays, we observed that both the statins and SREBP could specifically induce PPARgamma-mediated transcription. However, the statins do not appear to signal through SREBP. Furthermore, our results indicate that SREBP utilizes PPARgamma's transcriptional activity to induce PTEN transcription, whereas the statins signal through PPARgamma's protein activity to upregulate PTEN expression. Overall, our observations suggest that statins signal through another transcription factor, in a PPARgamma-dependent manner, which in turn induces PTEN transcription. We, therefore, studied the full-length PTEN promoter through serial deletion reporter assays and electromobility shift assays and identified a region between -854 and -791 that binds an as-yet-unidentified transcription factor, through which the statins induce PTEN expression. Since PTEN is constitutively active, our data indicate it may be worthwhile to examine statin and SREBP stimulation as mechanisms to increase PTEN expression for therapeutic and preventative strategies in cancer, diabetes mellitus and cardiovascular disease

PTEN dysfunction in Cancer and Autism

I will cover this point in more detail in the post on PTEN, but note that the PTEN gene dysfunctions found in 10% of people with autism are generally different to the ones found in cancer.  We also have the difference between whether the PTEN gene is mutated or there is PTEN loss.

There should be two identical copies of the PTEN gene. When one copy is mutated, the protein it produces was found to inhibit the protein produced by the good copy. In other cases, one copy of the PTEN gene is OK, but the other got deleted.   This turned out to be better than having one mutant version.

Different mutations in PTEN are linked to different outcomes.  The known autism mutations are called H118P, H93R and H123Q.  If you have a C124S mutation you would be at risk of something called thyroid follicular carcinoma and not autism.

It is all very complicated and I have to say some conclusions in the research are contradictory.

But it is reported that about 10% of people with autism have an identifiable PTEN mutation.  I am more interested in whether PTEN is an interesting protein in the other 90%.

We saw in the fragile X research that even though this affects only 1% of cases with autism, some experimental therapies for fragile X worked on people with autism, but without fragile X.  At the time I thought that very odd.

My assumption is that PTEN is interesting for more than the 10%.

Conclusion

So there are now 2 plausible reasons why statin therapy may be effective in people with classic autism and elevated cholesterol:-

·        Reduction in inflammatory cytokines 

·        Up-regulation of PTEN

Maybe it is both.

It may be that in people with autism and low cholesterol, and so not suited to statins, they may also have low levels of PTEN.

We saw in a recent post that when you eat fresh broccoli in addition to Sulforaphane, you also produce Indole-3-carbinol (I3C).   I3C also up-regulates  PTEN.

Using Peter logic, if statins have an immediate effect then quite likely so would I3C.

Whatever Next?

Well, for those few of you who have discovered the “magical” beneficial effects of mast cell stabilizers, like Verapamil and Cromolyn Sodium, on both autistic behaviours and severe allergies, here is a preview of what is coming next:-

PPAR-gamma modulates allergic inflammation through up-regulation of PTEN

Recent studies have indicated that PPAR-gamma plays an important role in anti-inflammatory responses and that PPAR-gamma signaling is associated with regulation of PTEN expression. It is known that up-regulation of PTEN expression reduces asthmatic pathogenesis.

These findings suggest that PPAR-gamma uses PTEN to modulate asthmatic responses The signaling mechanism by which stimulation of PPAR-gamma with the agonists regulates PTEN expression as well as Akt phosphorylation remains to be lucidated. However, our results agree with the observation that the anti-inflammatory action of PPAR-gamma agonists is mediated via up-regulation of PTEN.

In other words, increasing PTEN minimizes allergies.  Perhaps, via feedback loops, increasing allergies reduces PTEN?

Seizures also reduce PTEN.

Reduced PTEN leads to increased autistic behaviours.

Not surprisingly we will come back, yet again, to mast cells.

For us, it really does seem that PTEN is a key piece in the puzzle;  but a puzzle with a solution.