Remember paclitaxel?

 I refer you to 'The treatment conversation I and II' way back in the day...

Entangled Lives by Melvyn Sheldrake was a welcome Christmas present. I haven't got far into it but have already gone down a fascinating wormhole after reading that paclitaxel is made by fungi living in the yew trees. The fungi are endophytes (living inside plants) and it would appear there are loads of them.  It seems that both the yew tree and some or all of the fungi living there are making the compound. It also seems that there are a lot of fungi living there. One study found 150 fungal species in common yew in Iran, a Chinese study found 81 species with at least three producing paclitaxel, another Chinese study found 528 'strains' of endophytic fungi in 

In 2015 Science Direct summarised an article from Current Biology about this -  https://www.sciencedirect.com/science/article/pii/S0960982215011793 .

Yews grow in a way that should leave them particularly open to wood-degrading fungi;  producing lots of branches from under-bark buds, they are prone to cracked bark which provides an entrance wound for pathogenic fungi to enter with ease. Yet they are among the most long-lived trees in the world. 

What I take from the article is that at least some of the endophytic fungi living in yew trees produce paclitaxel. This acts on wood-degrading fungi that would threaten the yew in the same way that it acts in chemotherapy - reducing cell division and promoting cell death by interfering with the microtubules that provide necessary structural support within the cell to the division process.

At least one species of endophyte is triggered to produce paclitaxel when it detects and chemical which is produced when lignin (wood) is broken down by fungal pathogens. The paclitaxel is produced in hydrophobic bodies within its hyphae and it appears this tactic prevents the paclitaxel interfering in the endophyte's own cell division. The endophyte 'drops' the hydrophobic body with its paclitaxel cargo near the site of the pathogen invasion.

Lots of the articles that come up on the interweb when I searched seem to be from the biotechnology disciplines. Yews are getting a bit thin on the ground due at least partly to exploitation for paclitaxel, so culture of plant cells has been important for making the compound. Now maybe there's a search for the fungus that does the best job in making paclitaxel. One article tests paclitaxel production by a fungus in cell culture on its own or with yew cells as well. It does better when both types of cells are present...

Why don't all trees have such fungi? Did the yew produce the paclitaxel and then the fungi 'learnt' to do it too? Ain't evolution wild?


Comments

Post a Comment

Popular posts from this blog

The support hammock

Image
17.4.18 I feel as if I'm lying about in a comfy hammock made of people linked together caring for me and holding me up. It was a bit hairy getting into the hammock, and it's a long way above terra firma but now I'm there I feel pretty relaxed. How horrible it must be to be in this situation at an older age, with fewer friends left and family maybe elsewhere. There are the professionals including a little team of Clinical Nurse specialists (CNSs) who are pretty much at the end of a phone. There's the Macmillan Advice and Info centre, also at the end of a phone, but with a physical presence in the UCLH Macmillan Cancer Centre. There's a 'Living Room' there - at least a couple of meanings wrapped up in that  name I think - where you can hang out, and make tea or coffee without having to wash your mug up afterwards - just put it in the dishwasher! Very useful when you're there for things with long waits, although I now have the Grant Museum of Zo...
Read more

BACK ON THE JUICE - 6 JULY 2023 - ATOV TRIAL CYCLE 2

 So, I'm Patient 2 on the Atov trial, and have been randomised onto the adaptive treatment arm. This means that I start off with three cycles of carboplatin at three-weekly intervals. First one was on 15 June - 500mg by infusion as usual, followed by the expected days of sick tiredness, gradual improvement, then back to my new normal which is sadly not as good as the old normal.  I was told not to expect a sufficient reduction in Ca 125 after this to allow a reduction in dose so soon. This managed my expectations nicely, but in fact Ca125 had dropped by 55% - memo to self to get the actual numbers - so I'm in today having an 80% dose of carboplatin (400mg) - memo to self to ask for the dose calculation formula. Same dose of anti-sickness pre-meds and think I'll be sent home on usual doses of anti-sickness post-meds but I'm very (self) interested to see if the side effects are less bad on this only slightly lower dose of carboplatin, or if they perhaps pass more swiftly....
Read more

Kicking off

Image
Dearest readers. I don't have enough thanks for all of you who have taken an interest in what's been going on with me. Your presence, distractions, words, cards, flowers, messages have given me a fantastic sense of support. I'm sorry that in return I haven't always been able to get back to everyone and I can't remember what I've said to whom and end up boring endlessly about the same things. So a leap into the 20th century seemed like a good idea for keeping anyone who wants to know informed - and maybe give me an outlet for venting spleen (while I've still got one). My apologies if the latter means there is too much information. And before I continue - thank you to whoever sent the mystery flowers...I haven't been able to track you down, but it said 'With love x' on the tag How did I get here? On 20th January, I cycled energetically to GP with 'a change of bowel habit'. GP found lump in my belly - referred me for colonoscopy. I r...
Read more