Final answer:
The correct sequence of true (T) and false (F) statements regarding cancer is: F, F, T, T. This aligns with option D, signifying that cancers tend to become more heterogeneous as they progress, and knocking out oncogenes like Ras or Myc would decrease, rather than increase, cancer incidence. Wnt signaling's role in colorectal cancers and genome destabilization in a subset of these cancers being true statements.
Step-by-step explanation:
To indicate the true (T) and false (F) statements regarding cancer:
- Cancers become less and less heterogeneous as they progress. This statement is False. As cancers progress, they generally become more heterogeneous due to ongoing mutations and selective pressures within the tumor microenvironment.
- Knocking out Ras or Myc genes individually leads to a higher incidence of cancers in mice, and knocking out both genes simultaneously has an even stronger phenotype. This statement is False. Ras and Myc are known proto-oncogenes, and knocking them out would generally be expected to reduce cancer incidence, not increase it.
- Wnt signaling is important in colon epithelial cells, and mutations in genes in the Wnt pathway are present in most colorectal cancers. This statement is True. Alterations in the Wnt signaling pathway are a hallmark of many colorectal cancers.
- Genome destabilization in a subset of colorectal cancers that have defects in DNA mismatch repair takes the form of chromosome breaks, translocations, and deletions. This statement is True. However, the more characteristic feature is microsatellite instability, which indicates defects in DNA mismatch repair, typically without large-scale chromosomal abnormalities.
The correct sequence of answers is: F, F, T, T, correlating to option D.