LS10 Molecular diagnostics review
Lesson 1 Bench to bedside, translational medicine/research
A diagnosis can be made through emergency presentation
(symptoms), screening (imaging e.g.
mammography/colonoscopy), and laboratory tests (e.g. PAP,
BRCA1, etc.)
→ Characteristics of a good test:
★ It should be sensitive, so it should be able to detect
small amounts, even in the presence of other
molecules → gives info about the % of false negatives
★ It should be specific, so only the target molecule is
detected (positive result) → and provides info about
the % of positive samples
★ High throughput
★ Cheap
★ Automation, for simple and standardized procedures
Imaging is done when we want to look for localization, stage of tumor and
growth, tumor dissection, radiation localization, monitor recurrence, and see
whether drugs work or fail.
★ E.g. MRI/mammogram, based on the interaction of electromagnetic
radiation with the body tissue/fluids you can get sound waves that
can be visualized
In translational medicine, we translate clinical questions into research.
Why do some tumors grow faster? e.g. HER2
★ Human epidermal growth factor receptor (HER2) is amplified in
20-30% of cases of breast carcinomas
★ The more HER2, the shorter the survival, and how worse the
therapeutic response
How is the presence of HER2 detected?
★ Using fluorescent in situ hybridization (FISH) to localize DNA sequences using probes
★ In FISH, the target sequence is labeled. This is denaturated along with the probe, and
where there is binding you will see hybridization of the probe to the target DNA which
gives off a fluorescent signal
, HER2 targeting treatment
★ Herceptin (Trastuzumab) is a monoclonal antibody that targets HER2 and is used in
HER2 + patients
★ Resistance to the Herceptin treatment can occur, possibly because HER2 is present but
does not work?
★ Effects of drugs can differ in vitro and in vivo → in vitro means using 3D models e.g.
spheroids, organotypic co-culture, tumor on-chip, etc.
Imaging in research: Intravital microscopy (IVIS)
★ In the figure, you can see a transgenic mouse with labeled
bloodvessels →
★ This has been done to visualize the inhibition of angiogenesis
with anti-VEGF antibodies to see whether Bevacizumab works
against VEGF
★ Intravital microscopy can be used in drug behavior to help
explain the different possible scenarios of a drug → e.g.
incomplete tissue penetration, heterogeneous cell population, or
off-target drugs
Lesson 2 FRET in drug development and immunological diagnostics
FRET = fluorescent resonance energy transfer
★ There is a donor and acceptor when they overlap, they
interact and you’ll get excitation so there will be a
fluorescence peak/signal
★ Excitation of donor (increase) = emission of acceptor
(decrease)
★ FRET can be used to study protein-protein
interactions
Example: FRET in chronic myeloid leukemia
★ To study protein conformational changes/folding
★ In chronic myeloid leukemia there is a translocation of
BCR to ABL, so it becomes a fusion protein
★ Because of this, there is constitutively active tyrosine
kinase (novel target drug) which leads to the
phosphorylation of CrKL which is associated with
leukemia
Lesson 1 Bench to bedside, translational medicine/research
A diagnosis can be made through emergency presentation
(symptoms), screening (imaging e.g.
mammography/colonoscopy), and laboratory tests (e.g. PAP,
BRCA1, etc.)
→ Characteristics of a good test:
★ It should be sensitive, so it should be able to detect
small amounts, even in the presence of other
molecules → gives info about the % of false negatives
★ It should be specific, so only the target molecule is
detected (positive result) → and provides info about
the % of positive samples
★ High throughput
★ Cheap
★ Automation, for simple and standardized procedures
Imaging is done when we want to look for localization, stage of tumor and
growth, tumor dissection, radiation localization, monitor recurrence, and see
whether drugs work or fail.
★ E.g. MRI/mammogram, based on the interaction of electromagnetic
radiation with the body tissue/fluids you can get sound waves that
can be visualized
In translational medicine, we translate clinical questions into research.
Why do some tumors grow faster? e.g. HER2
★ Human epidermal growth factor receptor (HER2) is amplified in
20-30% of cases of breast carcinomas
★ The more HER2, the shorter the survival, and how worse the
therapeutic response
How is the presence of HER2 detected?
★ Using fluorescent in situ hybridization (FISH) to localize DNA sequences using probes
★ In FISH, the target sequence is labeled. This is denaturated along with the probe, and
where there is binding you will see hybridization of the probe to the target DNA which
gives off a fluorescent signal
, HER2 targeting treatment
★ Herceptin (Trastuzumab) is a monoclonal antibody that targets HER2 and is used in
HER2 + patients
★ Resistance to the Herceptin treatment can occur, possibly because HER2 is present but
does not work?
★ Effects of drugs can differ in vitro and in vivo → in vitro means using 3D models e.g.
spheroids, organotypic co-culture, tumor on-chip, etc.
Imaging in research: Intravital microscopy (IVIS)
★ In the figure, you can see a transgenic mouse with labeled
bloodvessels →
★ This has been done to visualize the inhibition of angiogenesis
with anti-VEGF antibodies to see whether Bevacizumab works
against VEGF
★ Intravital microscopy can be used in drug behavior to help
explain the different possible scenarios of a drug → e.g.
incomplete tissue penetration, heterogeneous cell population, or
off-target drugs
Lesson 2 FRET in drug development and immunological diagnostics
FRET = fluorescent resonance energy transfer
★ There is a donor and acceptor when they overlap, they
interact and you’ll get excitation so there will be a
fluorescence peak/signal
★ Excitation of donor (increase) = emission of acceptor
(decrease)
★ FRET can be used to study protein-protein
interactions
Example: FRET in chronic myeloid leukemia
★ To study protein conformational changes/folding
★ In chronic myeloid leukemia there is a translocation of
BCR to ABL, so it becomes a fusion protein
★ Because of this, there is constitutively active tyrosine
kinase (novel target drug) which leads to the
phosphorylation of CrKL which is associated with
leukemia
