6. Tumour Suppressor Genes (Retinoblastoma and the two hit hypothesis, p53)

Cancers occur as a result of damage (in the form of mutations) to a cells DNA that results in the formation of malfunctioning proteins. The mutated proteins give the cancerous cells a number of specific traits, outlined in the 'hallmarks of cancer' ( • 4. Hallmarks of Cancer... ).
The genes that are mutated in cancers can be divided into two groups - tumour suppressor genes and proto-oncogenes.
Tumour suppressor genes are genes that produce proteins that are involved in stopping mutated cells from dividing, and also act as the brakes on the cell cycle at its various checkpoints.
The retinoblastoma gene is a gene that is involved in stopping cells from crossing the G1 checkpoint in the cell cycle, preventing cells from entering S phase and replicating their DNA in preparation for cell division.
For the retinoblastoma gene to be rendered inactive, it needs a mutation in both of its copies (alleles). This is explained by the 'two hit hypothesis'.
P53 is another example of a significant tumour suppressor gene. It is active during the cell cycle, acting by halting damaged cells at the checkpoints and then ordering the cell to destroy itself by the process of apoptosis.

[@nannasrensen7674]

Don't you mean that the tumor supressor genes are dominant? If you only need one working one? The tumor supressor-inactivating mutation must be the one that's considered recessive? Or am I just comfused?

[@nannasrensen7674]

Apart from that, I love these videos - very clear and easy to understand explainations!

[@oncologyformedicalstudents6877]

Hi, thanks for the comment! Yes - listening back I would agree that is an error. You often hear people say tumour suppressor genes are recessive, as I had done here, but what is actually being referred to are loss of function mutations in tumour suppressor genes. Because we are focussed on what mutations lead to a cancer promoting phenotype, I probably would avoid referring to tumour suppressor genes as dominant, if only to avoid confusion!

[@nannasrensen7674]

@@oncologyformedicalstudents6877 thank you for the reply - makes sense! :)

[@indiabiologyexplains5013]

@@oncologyformedicalstudents6877 After watching a few more videos, I learned that in very rare cases, P53 mutations can be dominant. Is this true?

[@theoneh5249]

I have my exam in 2 days, and have struggled with getting my head around this for months. Thank you so much!!!

[@dr.paddlesmack2054]

this is amazing. don't worry about some of the negative comments. this has definitely made my understanding a lot more clear

[@ilovepathologyVijayPatho]

you have really made this simple.! loved it

[@guljafari3269]

thank you so much ... however I think the sniffing sound in the headphone gets a little irritating ...

[@dr.adilkhaliq8852]

very Impressive and perfect. Thank you for this effort.

[@ldyelphinium]

do u mind adding captions? the video is very helpful but i cant understand some parts due to ur pronounciation

[@ughsirius]

This was brilliant!! Thank you.

[@joory_a]

Thank you very much for making this so so simple

[@thirva95]

Sir this cleared all my doubts, thank you :)

loved the video! Every video has being more improved!!!!

[@emmayoung22]

Dude sounds like Alan Davies. Thanks, i have a biochem exam tomorrow!

[@sarahmina1442]

Thank you. So helpful!

[@Maryam0961]

Thanks for making it that simple =D I'll definitely go check your other videos while I study Pathology

[@karatefishman]

So helpful! Thanks a lot.

[@daisyxu3050]

Great video to make things clear! Retinoblastoma....haha such a long word!

[@EmanRapp]

Great video. 👍

[@workhard6261]

Have you watched Dr najeeb lectures, sounds like animated content of Dr najeeb videos.

[@cucuruto]

Hei dude, can you take subtitles english generation? That form stay easy to understand tks

[@coralav]

Great video!!

[@tinekerocks]

great video. Thank you for the review.

[@rsk81226]

Very helpful thanks a lot. 😍

[@51omeed17]

Good one man🔥

[@parinithamaben4141]

Great video! :)

[@missyfford4962]

i have rb and currently undergoing radiothearapy to treat it (: mine is very rare as im 12 and i have it, when its usually found in babies!

[@jahnvihora403]

how're you now

[@AMWE-gh7ti]

Useful videos!

[@dragomirflavius7392]

❤❤❤❤i have a test on this an you saved me

[@Sophia-dw8dj]

this was so helpful. thank you!

[@anleyteferra7846]

Thank you!

[@michelefk]

Love it but very hard to understand as I’m guessing you are sick with a cold or flu, constantly sniffing.

[@fajitaboys]

Why are the tumor supressor genes recessive and not dominant if they both need to be mutated in order to be taken out and thus allow for cancer??

[@Toothfairy1018]

awesome! thanks!

[@SforScience]

u can subscribe to my channel

[@123shainz]

Fabulous 👌

[@enterURLhere]

that tumour was sitting in the backseat of the car and the car was driving backwards???

[@SOSSTSE]

Thank You. 😊 SOSSTSE

[@jaju123456]

RB protein is pRb right, whereas RB is just the gene? Diagram might have got that wrong I think, should say pRb rather than RB.

[@oncologyformedicalstudents6877]

+jaju123456 Yep, that's right - or you can use italics to denote the protein - thanks for the feedback!

[@s.wahid06]

don't you use italics to denote gene?

[@oncologyformedicalstudents6877]

Yes you're right - thanks for the correction

[@cavessavia5378]

Thanks))))))

[@madosh9110]

clean your nose recording

[@immadisarojini2775]

Super

[@jenniferjdaidani1397]

the sniffing sound is very irritating. but thank you!

[@Akumpo3434]

I had got one of my eyes removed and now use prosthetic

[@Akumpo3434]

@Very Slothy I was pretty little and I think they put me under anesthesia then I remember at first it felt pretty weird but now I got used to it

[@aykenberdesh3852]

На русском есть? Do you have it in russian language? Somebody can translate it?

[@Clyne69]

Why is inherited RB bilateral while sporadic RB unilateral? Does it have to do with early onset makes it Bilateral blindness??????????

[@4204VR]

inherited RB isn't necessarily bilateral, it's just that tumor formation is much, much more likely in inherited RB (because only one mutation has to occur) so it's very frequently seen as bilateral tumors and/or multiple tumors per retina. Sporadic RB is almost always unilateral because it's rare to develop mutations in both copies of the RB protein, so usually only one tumor forms. As with almost everything in medicine, it's still very possible to see unilateral tumorogenesis in inherited RB and bilateral in spontaneous RB, it's just unlikely.

[@حيدرمحمدعبدالزهرة]

Hmmm, the tumor suppressor genes are recessive, don’t you mean that the mutation that disables a tumor suppressor genes is recessive, that’s why both genes need to be mutated in order to have a problem

[@oncologyformedicalstudents6877]

Hey thanks for the comment - someone else made a similar point a while back so I've pinned the reply, hope it helps

[@mamanipanigrahi9889]

What a voice!! 😍😘🐶

[@filafelphiasozoai4272]

great video + he sound cute with that nasal voice. :)

[@raedababneh7253]

👍👍

[@bharathchandran8343]

👍

[@wallacekarithi9292]

You have a bad cold . sorry about that ..Thanks for the video though

[@amrutharaghuraman2806]

8:40 P53

[@llyraa8443]

I had rb

[@wayne02058]

no thank YOU

[@gauharsarbasova8809]

Плохое видео невозможно слушать. Слышно причмокивания

[@wenirahayu491]

「ビデオのキャラクターそれは素晴らしいです、私はそれがとても好きです$$」、

[@sisaghayants7858]

The video was great but please change your voice man

[@zazaaladashvili5926]

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[@zarinsonali6390]

i am sorry to say but i think you were more focused on the way you were speaking rather than explaining. bro this is not an ielts exam so go easy man! and if you have a cold, you are teaching biology how could you not take medications before preaching?

[@Dronie-SkyVistas]

Whatever bro ur just jealous 🤣

[@hmnamd]

He looks like chewing something while talking , boring to listen to that chewing ( or kinda lips licking ) sound

[@thatmd]

Thank you!

[@tehreemfatima8139]

👍

[@chien-yilai470]

👍