Question

Those who inherit a mutant allele of the RB1 tumor-suppressor gene are at risk for developing a bone cancer called osteosarcoma. You suspect that in these cases, osteosarcoma requires a mutation in the second RB1 allele, and you have cultured some osteosarcoma cells and obtained a cDNA clone of a normal human RB1 gene. A colleague sends you a research paper revealing that a strain of cancer-prone mice develops malignant tumors when injected with osteosarcoma cells, and you obtain these mice. Using these three resources, what experiments would you perform to determine:
(a) Whether osteosarcoma cells carry two RB1 mutations
(b) Whether osteosarcoma cells produce any pRB protein
(c) If the addition of a normal RB1 gene will change the cancer-causing potential of osteosarcoma cells?

Accepted Answer

For part (a), to determine whether osteosarcoma cells carry two RB1 mutations, start by isolating genomic DNA from the osteosarcoma cells. Then, perform PCR amplification of the RB1 gene regions followed by DNA sequencing. Compare the sequences to the normal RB1 gene sequence to identify mutations in both alleles. Alternatively, use techniques like Southern blotting or allele-specific PCR to detect deletions or mutations in each allele. For part (b), to check whether osteosarcoma cells produce any pRB protein, extract total protein from the cells and perform a Western blot analysis using an antibody specific to the pRB protein. This will reveal the presence or absence of pRB and can also indicate if the protein is truncated or altered in size, suggesting a mutation affecting protein expression or stability. For part (c), to test if adding a normal RB1 gene changes the cancer-causing potential of osteosarcoma cells, transfect the osteosarcoma cells with the normal human RB1 cDNA clone. Then, inject these transfected cells into the cancer-prone mice and monitor tumor development compared to mice injected with untransfected osteosarcoma cells. A reduction in tumor formation would suggest that the normal RB1 gene suppresses the cancer phenotype. Throughout these experiments, include proper controls such as cells known to have normal RB1 alleles and cells lacking RB1 function to validate your assays and interpretations. Finally, analyze and interpret the data to understand the role of RB1 mutations and pRB protein expression in osteosarcoma development and progression, and how restoring normal RB1 function might impact tumorigenicity.

비슷한 문제에 대한 검증된 영상 답변:

주요 개념

Tumor Suppressor Genes and the Two-Hit Hypothesis

Gene Expression and Protein Production Analysis

Functional Complementation and Tumorigenicity Assays