In an experiment, cells were growing in a Petri dish that hadbeen coated with Extra-cellular matrix (ECM) components. A peptideadded to the dish caused the cells to detach from the ECM on thedish surface. The peptide was a disintegrin.

(a) From the statements below, which one best explains themolecular details of why the cells detached?                          [ Select ]                     [\"i\", \"ii\", \"iii\"]     

(i) Disintegrin competes with the RGD sequence of integrin forbinding ECM proteins (such as fibronectin). This disrupts theintegrin-ECM association.

(ii) Disintegrin competes with the RGD sequence of ECM proteins(such as fibronectin) for integrin binding. This disrupts theintegrin-ECM association.

(iii) Disintegrin binds to the RGD sequence of ECM proteins(such as fibronectin). This disrupts the integrin-ECMassociation.

(b) Which one of the following is the best explanation for whymetastatic cancer cells secrete disintegrin.                          [ Select ]                     [\"i\", \"ii\", \"iii\"]     

(i) Disintegrin prevents cells from interacting with the ECM sothat cells can migrate through connective tissue and into the bloodstream.

(ii) Cell migration involves focal adhesions that connect cellsto the ECM, but hemidesmosomes must be disrupted for a cell todetach from the basal lamina.

(iii) Cell migration involves changes in cadherin expressionthat allows cells to detach from the tissue and enter the bloodstream.

(c) Other factors promote cancer cells to metastasize. For eachof the following, decide whether metastasis would be promoted orinhibited.

Secretion of ECM proteases.                          [ Select ]                     [\"PROMOTED\", \"INHIBITED\", \"\", \"\"]     

Secretion of less fibronectin.                          [ Select ]                     [\"PROMOTED\", \"INHIBITED\"]     

Cell-cell interaction with endothelial cells of bloodvessels.                           [Select ]                      [\"PROMOTED\", \"INHIBITED\"]     

(d) When a cancer cell reaches a new site in the body, manycancer cell properties are required to allow it to form a newtumor? Decided which factors below would promote the growth of asecondary tumor and which ones would not.

(i) Expression of an integrin that binds to the type offibronectin that is present at the new site.                          [ Select ]                     [\"WOULD\", \"WOULD NOT\"]     

(ii) Expression of FLIP, which resembles procaspase 8 and 10 butlacks a proteolytic domain.                          [ Select ]                     [\"WOULD\", \"WOULD NOT\"]      

(iii) Expression of Apaf1.                          [ Select ]                     [\"WOULD\", \"WOULD NOT\"]