Oncology Q

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Oncology Q

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Tiff
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05/15/08 - 10:44 AM

An immunoperoxidase stain for the protease cathepsin D is performed on the microscopic tissue section from a breast carcinoma in a 61 year old female. There is pronounced cytoplasmic staining in the tumor cells. The presence of this marker is most likely to predict tumor:

A. Angiogenesis
B. Invasiveness
C. Differentiation
D. Heterogeneity
E. Aneuploidy

new_n_lost
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05/15/08 - 01:43 PM

I know this and i pretty much sure that i have read this somewhere.

Aneuploidy ????

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jean robert
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05/15/08 - 05:29 PM

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sigh
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05/15/08 - 07:12 PM

It has to be link to prognosis... so, B. or C. I go with B like Jean.

GoodGirl
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05/15/08 - 08:37 PM

Protease = dissolve connective tissue = invasivness = answer is B.

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Tiff
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05/16/08 - 08:39 AM

GoodGirl wrote:
Protease = dissolve connective tissue = invasivness = answer is B.

B is correct. As Goodgirl explains - Cathepsin D is a proteinase that cleaves fibronectin and laminin. High levels are associated with greater invasiveness.

Here's my question - Cathepsin D cleaves laminin and increased levels are associated with invasivenss. Tumor clls have more laminin receptors than normal cells so that they can attach to membranes at distant sites. Wouldn't it make sense that if a protease is cleaving laminin, the tumor has less opportunity to metastasize? Also if protease is cleaving laminin how is it causing increased invasiveness and not less? Isn't the cleaving of laminin reducing the adhesiveness?

GoodGirl
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05/16/08 - 01:03 PM

Seems to me stronger a cancer cell attaches to the basal membrane bc of higher number laminin receptor = stronger the invasiveness of Ca is. You got confused a bit, 1st step is attachment and then cleavage of BM or extracellular matrix ( 2nd step ) with help of proteases( realesed from cancer cells ) and other enzymes . This gives invasive potential to cancer.

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Tiff
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05/16/08 - 02:17 PM

GoodGirl wrote:
Seems to me stronger a cancer cell attaches to the basal membrane bc of higher number laminin receptor = stronger the invasiveness of Ca is. You got confused a bit, 1st step is attachment and then cleavage of BM or extracellular matrix ( 2nd step ) with help of proteases( realesed from cancer cells ) and other enzymes . This gives invasive potential to cancer.

Ah ha! Thank you much. It's much clearer now. cool

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