Another major component of carcinogenesis would be alteration
in genes that then evade apoptosis. Remember please that
in cancer it does'nt want apoptosis. So therefore, let me
give you an example as to how it does this exactly.
Our topic here brings us to BCL-2. Understand that on your boards,
you will be quite clear and you will not be able to confuse
BCL-2 with BCR. One has nothing to do with the other. When I say
BCR-ABL you're thinking about the fusion protein 9 and 22
dealing with tyrosine kinase and so forth. It's completely a
different discussion. Here however BCL-2 has everything to do with
a translocation called t(14;18). That chromosome 14 means what to
you? Immunoglobulin heavy chain. And follicular lymphoma what does
that mean to you. Well this is a lymphoma. If you take a look at
histologic pictures would you find Reed-Sternberg cells, yes or no?
No. So if you don't find Reed-Sternberg cell what kind of lymphoma
do we have? A Non-Hodgkin's lymphoma. One of the many types
that we shall take a look at but quite common a Non-Hodgkin's
lymphoma, follicular. So what does BCL-2 do for follicular lymphoma?
It protects the cell, the cancer cell from apoptosis. In other
words, it's an anti-apoptotic factor. You hear what I just said?
Language is important. Not pro-apoptotic but anti-apoptotic. In
this box here with clonal expansion, just a few words here about
how cancers like to behave. Clonality. Most of your cancers will
be monoclonal activity. What does that mean to you?
Well let's take a look. Sex chromosomes come together and you end
up forming a female zygote. Eventually blastocyst.
Inactivation of one X-chromosome. Now with neoplasia what ends up
happening is the fact that it only chooses one type here
to expand upon. Exactly why, well we don't know. Majority of your
cancers in fact will be monoclonal of type or monoclonality.
And in laboratory studies in oncology there will be certain enzymes
that oncologist use or researchers will use to then measure
the monoclonality and these are then called your what's known as
your isoenzymes. The polyclonal as the name implies,
will be one in which it has number of your chromosomes. But more
common though, monoclonality. You have heard of
monoclonal gammopathy of undetermined significance. You have heard
of multiple myeloma. All those are monoclonal type of cancers.