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View Diary: Dichloroacetate Redux: A Cancer Primer (53 comments)

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  •  Breast Cancer (5+ / 0-)

    A mechanism observed in breast cancer for example, is that some cancer cells have a receptor protein on their surface which responds to estrogen.  These are called ER cells (estrogen-receptor positive).  So estrogen then will stimulate these cells continuously, and they will proliferate abnormally.

    So yes, estrogen can have a cancer-inducing effect, but it's dependent on a particular genetic signature which is seen in some breast cancers, but not all.

    As a result, some women will benefit from drugs that interfere with estrogen, which then blocks the stimulation of the cancer cells.

    •  Here's a pretty good resource on this topic (4+ / 0-)
      Recommended by:
      Athena, TiaRachel, eve, ChemGeek

      if anybody wants more information:

      http://www.cancer.gov/...

      I'm a little unclear as to whether ER+ really means "any estrogen receptor is present" as some web pages seem to say, or whether it actually means "estrogen receptor up-regulation".  Either way, though, the idea is pretty much the same.

      And I'd like to fix a mistake in my previous post.  Estrogen receptors are not cell surface proteins as I implied.  They are inside the cell.

    •  Our understanding of Estrogen Receptors (3+ / 0-)
      Recommended by:
      Athena, eve, goldberry

      is changing rapidly. It is now known that there are multiple forms of ER. Typically, these are thought to be "nuclear receptors" that bind to estrogen inside the cell and then move to the nucleus where they can alter the expression of different genes.

      There is accumulating evidence that there are some estrogen receptors located on the surface of the cell membrane. Their mechanism of action and their functional relationship to other ER forms is the focus of ongoing study.

      Very complex and very interesting.

      •  Thanks, A Question (1+ / 0-)
        Recommended by:
        ChemGeek

        Thanks for this clarification - as soon as I posted this, I rethought my "surface" characterization.  I had to rethink and remember that steroid receptors are usually nuclear, not surface.

        But a more precise question:

        Do you know if the ER-positive breast cancer cells might have ER on their surface as well as nuclear receptors?  

        •  Membrane-associated ER (0+ / 0-)

          My reading of the latest studies indicate that ER+ breast cancer cells have both ER that can be found localized in the nucleus and at the cell membrane. The bulk of the data indicate that the membrane-associated estrogen-responsive receptors are very similar to the "classic" ER. It is likely that forms of the classic ER can become associated with the membrane as part of its "traffic" through the cell.

          However, there are researchers who maintain that there are non-classical receptors at the membrane that can respond to hormones including estrogen. For example, a "G-protein coupled" receptor termed GPR30 may play a role in allowing rapid responses to estrogen signalling -- pathways which would not directly involve action in the nucleus or alteration of gene expression. However, much more careful work will need to be done to provide compelling evidence for the presence of this or other non-classical estrogen receptors.

          If you are so inclined, you can check out this reference:

          "Nature of functional estrogen receptors at the plasma membrane"
          Ali Pedram, Mahnaz Razandi and Ellis R. Levin
          Molecular Endocrinology   yr:2006 vol:20 iss:9 pg:1996-2009

          Keep in mind, it's just one opinion.

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