‘RNA interference (RNAi)’ technology has gained popularity in the last few years. Why?

1. It is used in developing gene silencing therapies.
2. It can be used in developing therapies for the treatment of cancer.
3. It can be used to develop hormone replacement therapies.
4. It can be used to produce crop plants that are resistant to viral pathogens.

Select the correct answer using the code given below.

Correct Answer: 1, 2 and 4

RNA interference (RNAi) is a natural biological mechanism in which double-stranded RNA (dsRNA) molecules inhibit gene expression or translation by neutralizing targeted mRNA molecules. Let us evaluate each of the given statements step-by-step to understand why RNAi technology has gained significant popularity:

1. It is used in developing gene silencing therapies:
This statement is correct. RNAi functions primarily as a post-transcriptional gene silencing system. Synthetic small interfering RNAs (siRNAs) or microRNAs (miRNAs) can be introduced into cells to specifically bind to and degrade target mRNA sequences, thereby suppressing or "silencing" specific disease-causing genes.

2. It can be used in developing therapies for the treatment of cancer:
This statement is correct. RNAi technology allows for targeted gene silencing of oncogenes (genes that drive cancer proliferation) and mutated genes responsible for drug resistance in tumor cells. Consequently, RNAi-based therapeutics are actively being developed and tested for cancer gene therapy.

3. It can be used to develop hormone replacement therapies:
This statement is incorrect. Hormone replacement therapy (HRT) involves supplementing or substituting hormones (such as estrogen, progesterone, or insulin) that the body is not producing in sufficient amounts. RNAi works by down-regulating or silencing gene expression (inhibiting protein/RNA synthesis), not by producing or substituting missing hormones.

4. It can be used to produce crop plants that are resistant to viral pathogens:
This statement is correct. RNAi serves as a natural defense mechanism against viral infections in plants. By engineering transgenic plants to express specific dsRNA sequences matching viral genes, plants can recognize and degrade incoming viral RNA, granting them resistance to viral pathogens (as well as nematodes and insect pests).

Thus, statements 1, 2, and 4 are correct, making 1, 2 and 4 the correct choice.