Download Orexin-A, a peptide that can convince cancer cells to commit suicide

Orexin-A, a peptide that can convince cancer cells to commit suicide
Britta Wachter
signal transmission via several carrier
I’m gonna
kill
myself!
Cancer is a very common disease these days and many researchers are trying to find
ways to protect against cancer and to cure it. Just recently researchers found that a small
peptide, called orexin-A which can be found in many parts of the body (e.g. gastrointestinal
tract, pancreas, kidney, thyroid, lung, testis and placenta) can cause cancer cells to commit
suicide. To be able to hopefully apply these effect one day as an effective anti-cancer tool it
has to be found out how orexin-A exactly convinces the cells to commit suicide.
Cell suicide occurs for example when a cell gets a specific signal from its environment
that tells it to kill itself. To perceive signals in general, every cell possesses so called
“receptors” on its surface that function according to the “key-lock” principle. The receptors
are the locks and extracellular signals are the keys. When such a key finds its appropriate lock
and binds to it, it thereby activates a specific signal pathway in the cell. In this pathway
several carrier molecules transmit the message “key has bound to lock” to a terminal molecule
which then gives the cell further orders what to do next. Because a cell is receiving many
different signals at the same time, a huge amount of receptors exist as well as several
signalling pathways with different carriers. Orexin-A is one of these key-signals and its lock
is called OX1-receptor. In case of cell suicide, researcher found out that the terminal molecule
is p38. p38 is an enzyme that can amongst other things induce cell suicide.
In this study I tried to figure out what carriers are involved in the transmission of the
orexin-A signal that convinces the cell to commit suicide. For this reason, suggested carriers
have been genetically altered so they couldn’t work anymore or they have been blocked with
pharmacological substances. Then it was tested if the pathway still worked and the signal
arrived at the terminal stop or not. If the signal did not arrive at the terminal stop, it can be
suggested that, the blocked carrier-molecule is part of the signalling pathway. So far three
possible carriers have been identified. Two of them belong to the group of small G-proteins
and transmit the signal shortly after it was passed from the receptor to the first carriermolecule. The other identified carrier transmits the signal directly to the terminal stop. Further
research has been done to identify the remaining carriers involved in this pathway.
Degree project in biology fall 2007
Examensarbete i biologi, 20 p
Biology Education Centre and Department of Neuroscience, Uppsala University
Supervisor: Dr. Jyrki Kukkonen