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If you were attempting for the first time to develop a viral gene therapy for a monogenic disease, what factors would you need to consider in your selection of a vector? Explain your answer.

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Two essential factors to consider are: (...

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You are designing a somatic cell gene therapy protocol for spinal muscular atrophy, a genetic disorder that is caused by a defect in the Survival of Motor Neurons (SMN) gene. You have cloned the SMN cDNA. (a) What is the minimal cis-acting DNA regulatory element you would need to ligate to the SMN cDNA to get transcription of the cDNA in cells? (b) Assume that you decide to use retroviral-mediated gene transfer to introduce the SMN cDNA into the patient's target cells ex vivo. What are the advantages and disadvantages of this choice of vector for gene delivery? Is there another vector that would work better?

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(a) A promoter element would be the mini...

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Discuss recent evidence suggesting a role for microRNAs (miRNAs) in cancer progression.

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Recent evidence has shown that microRNAs...

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Recent studies suggest that the expression pattern of a set of human _______ in cancer samples defines that cancer type better than microarray expression data from a set of 16,000 mRNAs.


A) snRNAs
B) snoRNAs
C) miRNAs
D) rRNAs

E) All of the above
F) A) and C)

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What is a tumor suppressor gene?


A) A gene associated with tumor formation when its product does not function.
B) A gene associated with tumor formation when its product functions normally.
C) A gene that accelerates the cell cycle and leads to uncontrolled cell growth.
D) A gene that codes for a transcription factor involved in tumor formation.

E) All of the above
F) B) and D)

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Diagram the HIV-1 life cycle and indicate some of the popular targets for antiviral strategies.

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The HIV-1 life cycle can be divided into several key stages: attachment and entry, reverse transcription, integration, transcription and translation, assembly, and budding. 1. Attachment and entry: HIV-1 attaches to the host cell membrane and fuses with it, releasing its genetic material into the host cell. 2. Reverse transcription: The viral RNA is reverse transcribed into DNA by the viral enzyme reverse transcriptase. 3. Integration: The viral DNA is integrated into the host cell's genome by the viral enzyme integrase. 4. Transcription and translation: The integrated viral DNA is transcribed and translated into viral proteins. 5. Assembly: New viral RNA and proteins are assembled into new virus particles. 6. Budding: The new virus particles bud off from the host cell membrane, ready to infect new cells. Some popular targets for antiviral strategies include: 1. Entry inhibitors: These drugs prevent HIV-1 from attaching to and entering host cells by targeting viral envelope proteins or host cell receptors. 2. Reverse transcriptase inhibitors: These drugs block the action of the viral enzyme reverse transcriptase, preventing the conversion of viral RNA into DNA. 3. Integrase inhibitors: These drugs inhibit the action of the viral enzyme integrase, preventing the integration of viral DNA into the host cell genome. 4. Protease inhibitors: These drugs block the action of the viral enzyme protease, preventing the cleavage of viral proteins necessary for viral assembly. 5. Fusion inhibitors: These drugs prevent the fusion of the viral and host cell membranes, blocking viral entry into host cells. By targeting these key stages of the HIV-1 life cycle, antiviral strategies can effectively inhibit viral replication and reduce the viral load in infected individuals.

Does the "two hit" hypothesis explain the role of oncogenes and proto-oncogenes in cancer? Why or why not?

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No, because activated oncogenes/proto-on...

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Which statement is not true about retroviruses (RNA tumor viruses) .


A) Study of the oncogenes carried by retroviruses has led to major advances inunderstanding of the molecular basis of cancer.
B) Most human cancers are the result of a retroviral infection.
C) When a retrovirus infects a cell, its RNA genome is converted to DNA by the viral-encoded reverse transcriptase.
D) Occasionally retroviruses acquire a gene from the host that is normally involved in cellulargrowth control.

E) B) and D)
F) A) and B)

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As they light up their cigarette, a friend of yours tells you that they have heard that benzo(a)pyrene in cigarette smoke is not really a carcinogen. Set them straight.

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Benzo(a) pyrene is a "procarcinogen" in ...

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The most promising gene therapy clinical trial so far for cystic fibrosis used aerosol administration and


A) liposome-mediated gene transfer
B) adenovirus-mediated gene transfer
C) adeno-associated virus-mediated gene transfer
D) retrovirus-mediated gene transfer

E) A) and B)
F) C) and D)

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The key step in the generation of "safe" (replication-incompetent) viral particles for gene therapy is


A) creation of site-specific mutations in viral genes
B) provision of viral genes on a The key step in the generation of safe (replication-incompetent) viral particles for gene therapy is A) creation of site-specific mutations in viral genes B) provision of viral genes on a <sup>-</sup> (psi<sup>-</sup>) DNA C) use of a packaging cell line that is not immortalized D) deletion of the viral reverse transcriptase gene- (psi-) DNA
C) use of a packaging cell line that is not immortalized
D) deletion of the viral reverse transcriptase gene

E) C) and D)
F) A) and C)

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The vast majority of human cervical cancers are associated with high-risk human papilloma virus (HPV) . HPV is a


A) DNA tumor virus
B) RNA tumor virus
C) retrovirus
D) phage

E) B) and D)
F) A) and D)

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Describe the functional differences between c-Src and v-Src.

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c-Src and v-Src are two forms of the Src...

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Using retinoblastoma as an example, explain Knudson's "two-hit" hypothesis.

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Retinoblastoma is a rare type of eye can...

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After activation of wild-type p53 in response to DNA damage, what are two possible outcomes of p53 activity?

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After activation of wild-type p53 in res...

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Which type of gene therapy has not yet been tried in the clinic?


A) germline gene therapy
B) somatic cell gene therapy
C) ex vivo gene therapy
D) cancer gene therapy

E) C) and D)
F) None of the above

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A

Benzo(a) pyrene can induce formation of DNA adducts that interfere with replication and transcription. It acts by a


A) promoter insertion mechanism
B) enhancer insertion mechanism
C) nongenotoxic mechanism
D) genotoxic mechanism

E) C) and D)
F) B) and D)

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Why were gene therapy trials for SCID-X1 recently suspended despite very encouraging initial results of clinical trials?

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Gene therapy trials for SCID-X1, also known as X-linked severe combined immunodeficiency, have been suspended in the past due to concerns over the safety of the treatment, despite initial promising results. SCID-X1 is a genetic disorder that affects the immune system, leaving patients highly susceptible to infections. Gene therapy aims to correct the genetic defect that causes the disorder, potentially offering a cure. The initial results of gene therapy trials for SCID-X1 were indeed encouraging, as several patients successfully had their immune systems restored. However, the vector used to introduce the corrective gene into the patient's cells, a retrovirus, was found to have the potential to cause leukemia. In some of the early trials, a small number of patients developed leukemia because the retrovirus inserted the new gene next to an oncogene, which then became activated. The suspension of the trials was a precautionary measure to ensure patient safety while researchers worked on developing safer gene delivery systems. Since then, newer vectors, such as lentiviruses, have been designed to minimize the risk of insertional mutagenesis, where the insertion of the corrective gene disrupts the function of other genes, potentially leading to cancer. Researchers have also been exploring other methods of gene editing, such as CRISPR/Cas9, which allows for more precise editing of the genome and could potentially reduce the risk of unwanted genetic alterations. It is important to note that the status of clinical trials can change over time, and newer trials may have resumed with improved safety measures and protocols. The decision to suspend or resume gene therapy trials is often based on a careful risk-benefit analysis, with the ultimate goal of providing safe and effective treatments for patients with SCID-X1 and other genetic disorders.

Which is a present concern regarding the use of retroviral vectors for gene therapy?


A) They will integrate their DNA into the genome instead of remaining extrachromosomal DNA.
B) They will integrate their DNA into the genome in ways that disrupt or misregulate the expression of genes at or near the site of integration.
C) They will fail to introduce the therapeutic gene into any of the patient's cells.
D) They will cause retroviral disease.

E) A) and D)
F) None of the above

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Current strategies for anti-HIV-1 gene therapy aim to do all of the following except:


A) destroy every cell infected with HIV-1
B) reduce plasma viral load
C) improve patient quality of life
D) use ribozymes to cleave viral RNA

E) A) and D)
F) A) and B)

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