Question 2 Carcinomas are cancers of epithelial origin, while sarcomas are cance

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Question 2

Carcinomas are cancers of epithelial origin, while sarcomas are cancers of mesenchymal origin, and changes in gene expression are major drives of both types of cancer. The Epithelial to Mesenchymal Transition (EMT) is an important developmental process that occurs during embryogenesis, but may also be involved in tumorigenesis during adulthood.

(A) (6 points) Describe the biological process of EMT, and state which type of cancer would be most likely to arise if EMT were inappropriately activated in an adult tissue.

(B) (9 points) Describe three classes of genes whose expression must change for an epithelial cell to become a carcinoma cell.

(C) (9 points) Describe three behaviors that must change for an epithelial cell to become a carcinoma cell.

Explanation / Answer

EMT is anprocess by which the epithelial cells lose their cell polarity and cell adhesion and gain migratory and invasive properties to become mesenchymal stem cells , multipotent stems which have the potential to form a variety of other stem cells. This is due to :

1- Decrease in epithelial proteins

2- Decrease in cell adhesion molecules

3- Increase in Mateix metallo proteinases.

Lung cancers are mostly associated with this.

2nd question -

The three class of genes -

1- Proto oncogenes - These genes normally regulate proliferation and cell differentiation.

2- Tumor suppressor genes - They regulate thethe c cycle , allow the time for DNA Repair to occur. If mutated , damaged DNA would replicated causing tumorigenesis.

3- Apoptosis related gene - If mutated , there would be continuous replication of damaged DNA harbourimg cells.

3rd question -

1- Self sufficient - This means that they should replicate independent of the signalling / growth factor .

2- Evasion of apoptosis - This would lead to continuous replication with no check on proliferation.

3- Insensitive to immune response - There occurs selective growth of antigen negative cancer cells , preventing immune activation.

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