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MALDI imaging mass spectrometry for in situ proteomic analysis of preneoplastic lesions in pancreatic cancer.

Grüner BM, Hahne H, Mazur PK, Trajkovic-Arsic M, Maier S, Esposito I, Kalideris E, Michalski CW, Kleeff J, Rauser S, Schmid RM, Küster B, Walch A, Siveke JT - PLoS ONE (2012)

Bottom Line: Thymosin-beta 4 was found significantly increased in sera of mice with PanIN lesions.Upregulated PanIN expression of Albumin was accompanied by increased expression of liver-restricted genes suggesting a hepatic transdifferentiation program of preneoplastic cells.In conclusion we show that GEM of endogenous PDAC are a suitable model system for MALDI-IMS and subsequent LC-MS/MS analysis, allowing in situ analysis of small precursor lesions and identification of differentially expressed peptides and proteins.

View Article: PubMed Central - PubMed

Affiliation: II Medizinische Klinik, Technische Universität München, Munich, Germany.

ABSTRACT
The identification of new biomarkers for preneoplastic pancreatic lesions (PanINs, IPMNs) and early pancreatic ductal adenocarcinoma (PDAC) is crucial due to the diseases high mortality rate upon late detection. To address this task we used the novel technique of matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) on genetically engineered mouse models (GEM) of pancreatic cancer. Various GEM were analyzed with MALDI IMS to investigate the peptide/protein-expression pattern of precursor lesions in comparison to normal pancreas and PDAC with cellular resolution. Statistical analysis revealed several discriminative m/z-species between normal and diseased tissue. Intraepithelial neoplasia (PanIN) and intraductal papillary mucinous neoplasm (IPMN) could be distinguished from normal pancreatic tissue and PDAC by 26 significant m/z-species. Among these m/z-species, we identified Albumin and Thymosin-beta 4 by liquid chromatography and tandem mass spectrometry (LC-MS/MS), which were further validated by immunohistochemistry, western blot, quantitative RT-PCR and ELISA in both murine and human tissue. Thymosin-beta 4 was found significantly increased in sera of mice with PanIN lesions. Upregulated PanIN expression of Albumin was accompanied by increased expression of liver-restricted genes suggesting a hepatic transdifferentiation program of preneoplastic cells. In conclusion we show that GEM of endogenous PDAC are a suitable model system for MALDI-IMS and subsequent LC-MS/MS analysis, allowing in situ analysis of small precursor lesions and identification of differentially expressed peptides and proteins.

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Related in: MedlinePlus

Statistical analysis of mass spectra comparison of “lesions” against “normal”.(A) Overlay of an excerpt of the average spectra from the ROI-group “PanIN” (blue) and the ROI-group “WT” (pink). The spread of the single spectra intensities is indicated in bars; a.u. (arbitrary units). (B) Dot Plot of the intensity-distribution of the m/z-species 2829 in PanINs (blue) and WT (pink) of each single spectrum. (C) PCA based differentiation of the exocrine (pink) and PanIN (blue) tissue. (D) Re-visualization of significant peaks. The m/z-species 2829 clearly re-visualizes on PanIN lesions (upper panel, magnified in excerpt) whereas the peak at 6645 is specific for the exocrine compartment of the pancreas (lower panel, magnified on the right side). Below is the average spectrum of the measured section.
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pone-0039424-g002: Statistical analysis of mass spectra comparison of “lesions” against “normal”.(A) Overlay of an excerpt of the average spectra from the ROI-group “PanIN” (blue) and the ROI-group “WT” (pink). The spread of the single spectra intensities is indicated in bars; a.u. (arbitrary units). (B) Dot Plot of the intensity-distribution of the m/z-species 2829 in PanINs (blue) and WT (pink) of each single spectrum. (C) PCA based differentiation of the exocrine (pink) and PanIN (blue) tissue. (D) Re-visualization of significant peaks. The m/z-species 2829 clearly re-visualizes on PanIN lesions (upper panel, magnified in excerpt) whereas the peak at 6645 is specific for the exocrine compartment of the pancreas (lower panel, magnified on the right side). Below is the average spectrum of the measured section.

Mentions: Closer examination of PanIN-specific peaks revealed that the m/z-species 2790, 2812 and 2829 were discriminating PanINs from normal tissue (Figure 2A). The overlay of the average spectra from PanINs and normal pancreatic tissue revealed that in the latter the peaks were nearly not detectable (Figure 2A). Further statistical examination of these peaks (Wilcoxon test, Bonferroni correction) revealed p values below 0.00001. The distribution Box Plot and Principle Component Analysis (PCA) of PanINs and exocrine tissue depicted clear discrimination between the two groups (Figure 2B+C).


MALDI imaging mass spectrometry for in situ proteomic analysis of preneoplastic lesions in pancreatic cancer.

Grüner BM, Hahne H, Mazur PK, Trajkovic-Arsic M, Maier S, Esposito I, Kalideris E, Michalski CW, Kleeff J, Rauser S, Schmid RM, Küster B, Walch A, Siveke JT - PLoS ONE (2012)

Statistical analysis of mass spectra comparison of “lesions” against “normal”.(A) Overlay of an excerpt of the average spectra from the ROI-group “PanIN” (blue) and the ROI-group “WT” (pink). The spread of the single spectra intensities is indicated in bars; a.u. (arbitrary units). (B) Dot Plot of the intensity-distribution of the m/z-species 2829 in PanINs (blue) and WT (pink) of each single spectrum. (C) PCA based differentiation of the exocrine (pink) and PanIN (blue) tissue. (D) Re-visualization of significant peaks. The m/z-species 2829 clearly re-visualizes on PanIN lesions (upper panel, magnified in excerpt) whereas the peak at 6645 is specific for the exocrine compartment of the pancreas (lower panel, magnified on the right side). Below is the average spectrum of the measured section.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3383687&req=5

pone-0039424-g002: Statistical analysis of mass spectra comparison of “lesions” against “normal”.(A) Overlay of an excerpt of the average spectra from the ROI-group “PanIN” (blue) and the ROI-group “WT” (pink). The spread of the single spectra intensities is indicated in bars; a.u. (arbitrary units). (B) Dot Plot of the intensity-distribution of the m/z-species 2829 in PanINs (blue) and WT (pink) of each single spectrum. (C) PCA based differentiation of the exocrine (pink) and PanIN (blue) tissue. (D) Re-visualization of significant peaks. The m/z-species 2829 clearly re-visualizes on PanIN lesions (upper panel, magnified in excerpt) whereas the peak at 6645 is specific for the exocrine compartment of the pancreas (lower panel, magnified on the right side). Below is the average spectrum of the measured section.
Mentions: Closer examination of PanIN-specific peaks revealed that the m/z-species 2790, 2812 and 2829 were discriminating PanINs from normal tissue (Figure 2A). The overlay of the average spectra from PanINs and normal pancreatic tissue revealed that in the latter the peaks were nearly not detectable (Figure 2A). Further statistical examination of these peaks (Wilcoxon test, Bonferroni correction) revealed p values below 0.00001. The distribution Box Plot and Principle Component Analysis (PCA) of PanINs and exocrine tissue depicted clear discrimination between the two groups (Figure 2B+C).

Bottom Line: Thymosin-beta 4 was found significantly increased in sera of mice with PanIN lesions.Upregulated PanIN expression of Albumin was accompanied by increased expression of liver-restricted genes suggesting a hepatic transdifferentiation program of preneoplastic cells.In conclusion we show that GEM of endogenous PDAC are a suitable model system for MALDI-IMS and subsequent LC-MS/MS analysis, allowing in situ analysis of small precursor lesions and identification of differentially expressed peptides and proteins.

View Article: PubMed Central - PubMed

Affiliation: II Medizinische Klinik, Technische Universität München, Munich, Germany.

ABSTRACT
The identification of new biomarkers for preneoplastic pancreatic lesions (PanINs, IPMNs) and early pancreatic ductal adenocarcinoma (PDAC) is crucial due to the diseases high mortality rate upon late detection. To address this task we used the novel technique of matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) on genetically engineered mouse models (GEM) of pancreatic cancer. Various GEM were analyzed with MALDI IMS to investigate the peptide/protein-expression pattern of precursor lesions in comparison to normal pancreas and PDAC with cellular resolution. Statistical analysis revealed several discriminative m/z-species between normal and diseased tissue. Intraepithelial neoplasia (PanIN) and intraductal papillary mucinous neoplasm (IPMN) could be distinguished from normal pancreatic tissue and PDAC by 26 significant m/z-species. Among these m/z-species, we identified Albumin and Thymosin-beta 4 by liquid chromatography and tandem mass spectrometry (LC-MS/MS), which were further validated by immunohistochemistry, western blot, quantitative RT-PCR and ELISA in both murine and human tissue. Thymosin-beta 4 was found significantly increased in sera of mice with PanIN lesions. Upregulated PanIN expression of Albumin was accompanied by increased expression of liver-restricted genes suggesting a hepatic transdifferentiation program of preneoplastic cells. In conclusion we show that GEM of endogenous PDAC are a suitable model system for MALDI-IMS and subsequent LC-MS/MS analysis, allowing in situ analysis of small precursor lesions and identification of differentially expressed peptides and proteins.

Show MeSH
Related in: MedlinePlus