Oncotarget3
www.impactjournals.com/oncotarget
The detection of driver genes
Besides the above methods, experimental methods
can detect and conform driver genes, and have the more
far-reaching signicant. For example, EGFR mutation
and ALK gene rearrangement, the driver genes of
pulmonary adenocarcinomas, have been well tested and
veried by experimental methods [21, 22]. On genome,
most laboratories usually believe uorescence in situ
hybridization (FISH) assays. Originally, the detection of
ROS1 gene rearrangement is by the mean of dual break-
part uorescence in situ hybridization (FISH) probes.
Recently non-in situ testing approaches, including next-
generation sequencing (NGS) and real-time PCR assays,
have been much potential to be independent methods
or supplementary tests to detect driver genes. As for
transcription, the course about mRNA resulting from
the rearrangement gene, RTPCR have been the another
approach. It is known that the ROS1 rearrangements only
account for 1–2% of occurrence in NSCLC [19], which
decreased the accuracy of laboratory ndings. However,
immunohistochemistry can solve the dilemma by detecting
the increased ROS1 protein levels, providing a supplement
for FISH screening test.
Fluorescence in situ hybridization
Fluorescence in situ hybridization (FISH), rooting in
radioactivity in situ hybridization technique during the late
1980s, is a nonradioactive molecular and cellular genetic
technique with uorescent tags instead of isotope labeling.
From December 2007 to April 2011, uorescence in-situ
hybridization (FISH) have been screening EGFR gene
variation from tumor samples derived from 149 subjects.
And FISH test were successfully treated in the majority
of 49 patients who conferred positive EGFR [23]. Thus,
FISH play an unshakable role in detection and screening
of driver genes. In general, the abnormalities about EGFR,
ALK, RET and ROS1 are well validated by FISH because
the results were widely accepted. The important portion in
FISH is the design about dual-colour break-apart probes,
which have the completely different uorochromes in the
3′end and the 5′ end. In order to distinguish two genes
such as ROS1(green uorochrome at 3′end) and ALK
(orange luorochrome at 3′) when they are run together on
the same side, the selection about the uorochrome color
at 3′ end need to be cautious [24]. Otherwise, some reports
indicate that the experimental material older than 6 months
may induce the low binding efciency of probes [25].
Immunohistochemistry
Immunohistochemistry (IHC) is the course
detecting special antigens (e.g. proteins) in some cells of
a tissue section according to the rationale that antibodies
specically bind to proteins in biological tissues. Its
name originates from the roots “immuno”, antibodies
participating in the method, and “histo” meaning tissue.
Albert Coons is the rst person to conceptualize IHC and
apply to practical laboratory in 1941.
If the level of detected genes is low, IHC with
relatively sensitivity, depending on how to dene the
threshold, is a much effective screening tool. However,
scoring IHC results have been not reaching a consensus due
to the different outcomes from different scoring approaches,
which is perfectly similar to FISH one [25]. In NSCLC,
Immunohistochemistry often acts as a supplemented trial
for the reason that IHC cannot quickly meanwhile test
multiple samples and have higher cost than FISH.
Non-in situ technologies
Compared with these experimental methods above,
non-in situ technologies have been, to some extent, more
meaningful and convenient. For now, there are RTPCR and
NGS applied to detect driver genes in NSCLC [26–29].
Making easily, meanwhile processing multiple
samples, relatively low-cost, and having high sensitivity
even reaching 100% are the reason why most laboratories
adopted RTPCR. To get the perfect outcome, we need
to prudently design primers (a key factor to PCR) and
assure easily depredated and polluted RNA quality.
Although RTPCR, as with FISH, easily leaves out low
expressed genes, a new method according to RTPCR
Table 1: Current treatment recommendation of NSCLCs
Stage* General treatment recommendations
IA Surgical resection
IB Surgical resection, can consider adjuvant chemotherapy in selected cases (e.g. tumor size > 4 cm)
IIA Surgical resection followed by adjuvant chemotherapy
IIB Surgical resection followed by adjuvant chemotherapy
IIIA Multimodality treatment: chemotherapy, radiation, +/− surgery
IIIB Multimodality treatment: chemotherapy and radiation
IV Chemotherapy, consider targeted therapies according to driver mutations
*described according to TNM.