2 research outputs found
Mitochondrial Proteomic Analysis of Cisplatin Resistance in Ovarian Cancer
Epithelial ovarian cancer (EOC) is the leading cause
of death among
women with gynecologic malignancies and accounts for approximately
6% of cancer deaths among women. Cisplatin and its analogues form
the backbone of the most active chemotherapy regimens in advanced
EOC; however, development of platinum resistance is common and typically
marks a transition in which curing the patient is no longer possible.
An emerging theme in many cancers is that mitochondrial dysfunction
contributes to an aggressive carcinogenic phenotype. We hypothesized
that changes in the mitochondrial proteome are required to support
development of cisplatin resistance in human EOC. To investigate this
hypothesis, an organellar proteomics approach was utilized to quantify
alterations in protein abundance in mitochondria enriched from isogenic
cisplatin-sensitive (A2780) and -resistant (A2780-CP20) human EOC
cells. Protein isolates from mitochondria-enriched fractions were
analyzed by high resolution liquid chromatography–tandem mass
spectrometry (LC–MS/MS), and relative abundance of identified
proteins was quantified by spectral counting. Pathway analyses revealed
significant increases in notch signaling pathways, cell survival,
and alternate apoptotic pathways in the A2780-CP20 subtype. Among
the alterations identified in the mitochondrial proteomic composition
in cisplatin-resistant EOC cells, activated leukocyte cell adhesion
molecule (AKAP12) and A kinase anchoring protein 12 (AKAP12) were
elevated, while nestin was diminished in the mitochondrial fraction
of A2780-CP20 relative to A2780. This was verified by immunoblot analysis.
These results confirm that important changes in the mitochondrial
proteome, many of which promote evasion of apoptosis and tumor invasiveness
and metastasis, are present in cisplatin-resistant EOC
Elevated AKAP12 in Paclitaxel-Resistant Serous Ovarian Cancer Cells Is Prognostic and Predictive of Poor Survival in Patients
A majority
of high-grade (HG) serous ovarian cancer (SOC) patients
develop resistant disease despite high initial response rates to platinum/paclitaxel-based
chemotherapy. We identified shed/secreted proteins in preclinical
models of paclitaxel-resistant human HGSOC models and correlated these
candidate proteins with patient outcomes using public data from HGSOC
patients. Proteomic analyses of a HGSOC cell line secretome was compared
to those from a syngeneic paclitaxel-resistant variant and from a
line established from an intrinsically chemorefractory HGSOC patient.
Associations between the identified candidate proteins and patient
outcome were assessed in a discovery cohort of 545 patients and two
validation cohorts totaling 795 independent SOC patients. Among the
81 differentially abundant proteins identified (<i>q</i> < 0.05) from paclitaxel-sensitive vs -resistant HGSOC cell secretomes,
AKAP12 was verified to be elevated in all models of paclitaxel-resistant
HGSOC. Furthermore, elevated AKAP12 transcript expression was associated
with worse progression-free and overall survival. Associations with
outcome were observed in three independent cohorts and remained significant
after adjusted multivariate modeling. We further provide evidence
to support that differential gene methylation status is associated
with elevated expression of AKAP12 in taxol-resistant ovarian cancer
cells and ovarian cancer patient subsets. Elevated expression and
shedding/secretion of AKAP12 is characteristic of paclitaxel-resistant
HGSOC cells, and elevated AKAP12 transcript expression is a poor prognostic
and predictive marker for progression-free and overall survival in
SOC patients