The new research, published in an early view article in the Journal of Proteome Research not only identified potential biomarkers but also common pathways and crosstalking between those pathways.
This information could help develop treatment strategies that simultaneously inhibit multiple key kinase signalling pathways that optimise the overall therapeutic benefit of anticancer agents.
The researchers, led by Dr Wei Zhang of the University of Texas M.D. Anderson Cancer Center, US, used custom designed protein microarrays to study the relationships between different signalling pathways in different types of cancer cell.
These cancer cell lines comprised 12 different types of cancer cell, including breast, colon, glioma (a cancer of the central nervous system), kidney, leukaemia, lung, lymphoma, melanoma, ovarian, pancreatic, prostate and sarcoma (a soft tissue cancer).
By profiling multiple components of aberrant signalling pathways at the same time using the array the researchers could determine potential relationships between the signalling pathways of different types of cancer.
The cell lines were first lysed and diluted before being printed on PVDF-coated slides using a G3 robotic array spotter from Genomic Solutions.
Each slide was then incubated with 53 antibodies for specific signalling pathways including: PI3-K, growth factor / integrin signalling, apoptosis, cell cycle and others.
Protein expression levels and their phosphorylation status were then observed using a DakoCytomation catalysed signal amplification kit from Dako, US.
The results showed that the PI3-K pathway was up-regulated in several different tumour types while the VEGF angiogenesis (vascular endothelial growth factor) pathway was down-regulated in haematopoetic tumours.
Analysis of individual cancer types showed the up-regulation of the PI3-K (phosphoinositide 3-kinase) signalling pathway in glioma, with the cyclin-dependant kinase (CDK), a protein that couples mitogenic and antimitogenic extracellular signals with the cell cycle, being most significantly overexpressed.
Colon cancers have high levels of retinoblastoma (Rb) and the proto-oncogene c-myc proteins compared to the other types of cancer, whereas sarcoma have significantly lower levels of Rb and RSK (Ribosomal s6 kinase) along with a high expression level of CDK4 inhibitor p16ink.
Lung cancer cell lines were shown to exhibit lower expression of MAPK (mitogen-activated protein kinase) and cytochrome IV-2 than other cancer cell lines while expressing higher levels of total and phosphorylated pyruvate dehydrogenase kinase (PDK).
Both pancreatic and prostate cancers showed increased levels of IGFBP2 (insulin-like growth factor binding protein 2) expression although pancreatic cancer was the only type of cancer where EGFR was significantly differently expressed and clustered with another protein - phosphorylated c-Src (a proto-oncogenic tyrosine kinase).
