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55-213 (36)
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55-213 Lecture 24 notes.pdf
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Department
Biological Sciences
Course
55-213
Professor
Hubberstey
Semester
Winter

Description
Lecture 24 2013-01-10 2:29 PM Introduction:)cancer! • Role!of!microRNAs!in!cancer! • Cancer!is!an!incredibly!complicated!disease,!because!its!at!least!150!types!of! diseases! • Its!an!uncontrolled!regulation!of!growth!in!the!cell! • How!to!stop!or!treat!a!cancer!cell!is!incredibly!complicated! • Cells!dividing!uncontrollably!with!nothing!to!stop!them! • All!of!the!genes!involved!in!cancer!are!all!genes!that!we!have!in!our!cells!–!its!just! something!happens!to!them!during!the!process!of!carcinogenesis!where!they!pick!up! mutations:! o Activating!mutations!=!oncogenes.!Transcription!factor!telling!cell!to!divide! and!it!can’t!say!no! o Dedividing!at!G1!and!such!ogenes.!These!are!genes!that!tell!the!cell!to!stop! • The!myth!of!cancer!is!that!you!get!a!mutation!in!a!critical!gene!and!you!get!cancer!–! that’s!not!the!case!! • See!last!slide!of!previous!lecture! ! MultiMhit)hypothesis)of)cancer:! • Came!out!in!the!late!80s! • Scientists!found!there!was!a!whole!range!of!different!mutations! • No!single!mutation!in!one!gene!can!cause!cancer!by!itself! • One!mutation!isn’t!enough!to!cause!cancer!!This!is!because!there’s!too!many! checkpoints!and!redundancies!built!in!our!cells!to!prevent!such!thing! • However,!successive!mutations!can!eventually!lead!to!cancer! • A!single!mutation!leads!to!second!mutation,!third,!and!so!on! • If!the!cell!doesn’t!kill!itself!because!of!that!mutation!(i.e.!it!goes!through!the!cell! cycle!a!bit!faster),!it!can!influence!more!mutations!because!things!like!checkpoints! can’t!work!properly! • Either!the!cell!kills!itself,!or!other!mechanisms!start!happening!that!protect!that!cell! from!dying! • The!mutations!usually!occur!in!both!oncogenes!and!tumour!suppressors! • A!whole!bunch!of!different!genes,!be!it!oncogenes!or!tumour!suppressors,!have!to! be!hit!along!a!very!long!process!in!order!for!the!initial!mutated!cell!and!its!progeny! to!absorb!all!the!different!mutations!=!multi_hit!process! • In!colon!cancer,!the!multi_hit!process!can!take!several!years,!even!decades! • In!other!cancers,!it!takes!much!less!time,!some!in!terms!of!months! • See!figure:!multi_hit!hypothesis!! • Eventually,!over!time!(whether!months!or!years),!you’ll!get!cancer! • There’s!a!good!theory!currently!that!some!of!us,!if!not!all!of!us,!get!cancer!at!some! point!in!our!lives.!The!body!deals!with!it!by!either!removing!it!or!dealing!with!it.! • There!was!a!study!where!they!looked!at!prostate!cancer!in!men!that!died!of!non_ cancerous!causes.!They!found!that!80%!of!those!men!had!prostate!cancer!(way! more!than!expected).!This!supports!the!current!theory!! • See!picture!!!multi_hit!hypothesis! ! ! ! ! ! ! ! ! ! miRNAs)in)human)cancer:! • 50%!of!miRNA!genes!are!located!in!cancer_associated!genomic!regions!(regions! mutated!in!cancers)! • Several!miRNAs!have!been!isolated!that!are!involved!inc!ell!growth!and!apoptosis! (cell!death)! • Sometimes,!in!cancer,!the!apoptosis!process!is!surprised!–!so!the!cancer!cells!are!not! dying.!The!question!is!why?! • Chronic!lymphocytic!leukemia!(CLL)!–!13q14! o A!kind!of!leukemia! o
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