Question

GENE EXPRESSION PROFILE A RELATIVE EXPRESSION CYCLIN D RB E2F Information for the following problem: • CYCLIN D inhibits RB • RB inhibits E2F • E2F increases mitosis 1. Is the pattern seen in gene expression profile A consistent with cancer progression? If so, explain why you have come to that conclusion 2. If consistent with cancer progression, indicate the probable gene that is mutated, and if this represents an oncogenic or tumor suppressor mutation. In your explanation, make sure you explain e why you see the levels of each protein depicted in the graph.

Answer 1

1. In this picture it is shown that Cyclin D is inhibiting RB but RB is not inhibiting E2F protein. As a result gene expression profile of E2F is high which induces mitosis or cell division. So uncontrolled cell proliferation occurs which lead to cancer. So this graph describes a situation where cancer is occuring.

2. Retinoblastoma (RB) is a tumour suppressor gene.When RB is active or normal, it represses E2F gene which causes uncontrolled cell division. So, any mutation in tumour suppressor gene such as RB causes loss of control over cell division which ultimately lead to cancer.