miRNAs and Cancer

Question 1

What are miRNA?

Answer 1

Small RNA, 21-22 nucleotides long, controls expression of mRNA.

Question 2

Which proteins are miRNAs bound to in the cells?

Answer 2

Argonaute proteins.

Question 3

What does the miRNA target the bound Ago to?

Answer 3

Specific mRNA (by base pairing).

Question 4

What is the consequence of Ago protein binding to mRNA?

Answer 4

Degradation of that mRNA and/or suppression of proein synthesis from remaining mRNA.

Question 5

How may different types of mRNA sequences are known about?

Answer 5

Over 2000

Question 6

How many argonaute proteins are found in cells?

Answer 6

4

Question 7

Which other type of RNA is miRNA very similar to?

Answer 7

siRNA.

Not much difference between them, other than their origins.

Question 8

Which is the only argonaute protein that can cut?

Answer 8

Argonaute 2

Question 9

What type of change of expression of miRNA is commonly found in cancer?

Answer 9

Underexpression

Question 10

How can miRNA be used in cancer diagnosis?

Answer 10

1. Utilizing a signature of altered miRNA expression to differentiate cancer tissue from normal tissue.
2. Use of miRNA based calssifier to identify tissue of origin for cancers of unknown primaries.
3. Profiling circulating blood or tumour derived exosomal miRNAs, surpassing the invasive procedures to aid in early detection of cancers.
4. Distinguishing tumour subtypes using a panel of miRNAs that show differential expression within one cancer type.
5. Study SNPs in the miRNA genes. miRNA binding sites in the target mRNA genes or in the miRNA processing/machinery pathway genes to predict cancer predisposition.

Question 11

What are the best ways to study miRNA?

Answer 11

Measure amount and/or position
Interfere with activity.
Identify targets.

Question 12

How do miRNA PCR assays work?

Answer 12

1. Convert miRNA to cDNA via universal tailing and reverse transcription.
2. Add cDNA to RT qPCR master mix. Aliquot mixture across PCR array.
3. Run in your real-time PCR instrument.
4. Data analysis.

Question 13

What is the best way to study miRNA targets?

Answer 13

Ribonomics.

Question 14

What is ribonomics?

Answer 14

Uses genome wide tools to study how the interactions of RNAs and proteins modulate co-transcriptional and post-transcriptional regulation of gene expression.

Question 15

Have you done the further reading?

Answer 15

Do it, it’s examinable.