Because it is so efficient,
RNA interference represents a true revolution in many domains,
and it is also true for cancer.
I am confident that RNA interference will
facilitate the design of new cancer therapies and this is for two reasons.
First, because it allows to explore
all the pathways that are deregulated in cancer cells,
and thus discover new targets.
And second, because it might be used to inhibit
specifically noxious genes that are required for cancer cell survival.
For example, this slide summarizes what we know on colon cancer.
To go from a normal tissue to a cancer able
to invade other tissues and create metastasis takes many different steps,
and involves a number of various genes and pathways that more or less control cell fate.
And this does not take into account the fact that cancers are heterogeneous,
and even for a given cancer type there is
a very high level of variability between patients.
Let's review very briefly what we know about oncogenesis.
It all begins with the regulation of
the balance between cell proliferation and differentiation.
For example, in the skin the population of precursor cells proliferates,
which means that they go through the mitotic cell cycle,
the sequential series of events during which
each individual cell duplicates all its components,
including the genetic material,
and then divides and gives birth to two identical daughter cells.
The skin cell progresses from the bottom to the top in this picture.
At some point, the precursor cells exit from
the mitotic cycle and enter the terminal differentiation program.
And at the top what we find are fully differentiated cells.
In most tissues the cells have to exit from the mitotic cycle to
differentiate, and the number of cells that proliferate and
differentiate is strictly balanced.
Cell proliferation is controlled by negative signals or repressors that are switched off,