Transcript Lipidomics Update

LC-ESI-MS in parent mode and multiple reaction monitoring
(MRM) mode for determination of fatty acids and phospholipids
Fatty acids, particularly arachidonic acid (AA, 20:4 FA), and phospholipids,
especially lysophospholipids, including LPA, LPC, LPE, LPG, LPI, and LPS
were determined by LC-ESI-MS in parent mode and multiple reaction
monitoring (MRM) mode.
a. AA has been implicated as inflammatory mediators; it’s metabolites,
prostaglandin E2,can promote tumor growth;
b. Lysophospholipids (Lyso-PLs) are important cell signaling molecules,
such as lysophosphatidic acid (LPA), which enhances the invasion and
migration of cancer cells;
c. Phospholipase D activity leading to tumor
cell growth and motility by lysophosphatidic acid
production, and its expression is upregulated in
several kinds of carcinomas, like melanoma; PLA2
is also implicated in cancer development;
d. LC-ESI-MS in scan mode does NOT provide any lipids information in
samples.
Sample preparation for HPLC-ESI-MS/MS analysis
the MeOH method 1 for extraction of lipids: In brief, 10 µL of plasma were
added into 1 mL of MeOH with 500 pmol of 12:0 LPC, 100 pmol of 14:0 LPA
and 100 pmol of 17:0 Cer as the internal standard (IS). After vortex and
incubation on ice for 10 min, the mixture was centrifuged (10,000g, 5min,
room temperature), and 120 µL of supernatant were directly used for mass
spectrometry (MS) analysis.
Accurate measurement of lysophosphatidic acid by ESI-MS/MS in plasma
samples requires pre-separation of lysophosphatidylcholine. 2
1. Zhenwen Zhao, Yan Xu, An extremely simple
method for extraction of lysophospholipids
and phospholipids from blood samples. J Lipid
Res, 2010, 51: 652-659. PMID: 19783525.
2. Zhenwen Zhao, Yan Xu, Accurate
measurement of lysophosphatidic acid by ESIMS/MS in plasma samples requires preseparation of lysophosphatidylcholine. J
Chrom B, 2009, 877: 3739-3742. PMID:
19734112.
Data analysis
The experiment results
showed that:
1. 18:1 LPE was
significantly different in
patients with polyp or
colon cancer compared
with healthy controls.
2. The contents of AA,
22:6 FA, total FA, 18:0 LPI,
20:4 LPI, and total LPI in
polyp patient were the
most abundant, while
those in colon cancer were
the lest.
However, since only 9 controls,
12 patients with polyp, and
12 patients with colon
cancer samples were
analyzed, whether these
lipids could be used for
early diagnosis of colon
cancer merits further
studies.