This document discusses molecular biomarkers for cell signaling. It begins by defining biological markers or biomarkers as measurable indicators of disease, physiological changes, treatment responses, or psychological conditions. Molecular biomarkers specifically refer to measurable molecules that can serve these indicator purposes, such as glucose levels for diabetes management. The document then discusses how biomarkers are used in various scientific fields, including in medicine development to measure treatment effects as surrogate endpoints. For example, hemoglobin levels have been used to evaluate therapies for a rare disease called Type 1 Gaucher disease that causes multiple organ problems and shortened life expectancy. The document concludes by providing an overview of how cells typically communicate using chemical signaling molecules that bind to receptors on other cells and trigger intracellular response cascades leading to changes in
2. Biological Markers
A biological marker, or biomarker, is something that
can be measured, which points to the presence of a
disease, a physiological change, response to a
treatment, or a psychological condition.
A molecular biomarker is a molecule that can be
used in this way; for example, glucose levels are
used as a biomarker in managing diabetes. Non-
molecular biomarkers include medical images (for
example, MRI brain images can provide information
about the progression of multiple sclerosis).
3. Biomarkers are used in many scientific fields. They
are used in different ways at different stages of
medicines development, including in some cases as
a surrogate endpoint to indicate and measure the
effect of medicines in trials. For example,
haemoglobin levels have been used in Phase III
trials to support development of therapies for Type
1 Gaucher disease. This is a rare disease that affects
multiple organ systems and shortens life
expectancy, but it can take years to show any
clinical changes. Therefore clinical changes are not
a good way to evaluate the impact of new
treatments for this disease, and biomarkers that
show earlier changes required.
4. Cells typically communicate using chemical signals. These
chemical signals, which are proteins or other molecules produced
by a sending cell, are often secreted from the cell and released into
the extracellular space. There, they can float – like messages in a
bottle – over to neighboring cells.
Overview of cell signaling
5. Not all cells can “hear” a particular chemical message. In
order to detect a signal (that is, to be a target cell), a
neighbor cell must have the right receptor for that signal.
When a signaling molecule binds to its receptor, it alters
the shape or activity of the receptor, triggering a change
inside of the cell. Signaling molecules are often called
ligands, a general term for molecules that bind specifically
to other molecules (such as receptors).
The message carried by a ligand is often relayed through a
chain of chemical messengers inside the cell. Ultimately,
it leads to a change in the cell, such as alteration in the
activity of a gene or even the induction of a whole
process, such as cell division.
6. Thus, the original intercellular (between-cells) signal is
converted into an intracellular (within-cell) signal that
triggers a response.
