Separation and identification of differentially expressed nuclear matrix proteins between human esophageal immortalized and carcinomatous cell lines

Separation and identification of differentially expressed nuclear matrix proteins in breast carcinoma forming

BACKGROUND

Breast carcinoma is one of most prevalent malignant tumors occurring in women. Short of prevention, detection of breast carcinoma at an early, still curable stage would offer the best route to decrease its mortality rates. This highlights the urgent need for suitable biomarkers for early diagnosis and a better understanding of the disease pathogenesis.

MATERIAL AND METHODS

NMPs were extracted from normal human breast tissue (Group I), from hyperplastic mammary tissue specimens (Group II), from atypical epithelial hyperplasia specimens (Group III), and from breast carcinoma (Group IV) tissue. Differential proteome profiles were established and analyzed by means of immobilized pH gradient-based two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The different NMPs were analyzed in the National Center for Biotechnology Information (NCBI) database with Mascot software.

RESULTS

Well-resolved, reproducible 2-DE profiles of human breast tissues were obtained. Average protein spots were 904 +/- 58, 912 +/- 51, 931 +/- 63, 944 +/- 70 in Group I, Group II, Group III, and Group IV, respectively. Several different proteins were analyzed using mass spectrometry and bioinformation. Of these, 12 were well characterized. Compared to Group I, three proteins were up-regulated in Groups II, III, and IV, including Hsp27, prohibitin, and laminA/C. Upregulation was confirmed using Western blotting and immunohistochemical analysis. The correlation of prohibitin expression with clinicopathological features was also investigated.

DISCUSSION

The proteins identified in this study may potentially prove to be useful markers for breast carcinoma diagnosis.

Reproducibility, sensitivity and compatibility of the ProteoExtract subcellular fractionation kit with saturation labeling of laser microdissected tissues

Laser microdissection (LMD), a method of isolating specific microscopic regions of interest from a tissue that has been sectioned, is increasingly being applied to study proteomics. LMD generally requires tissues to be fixed and histologically stained, which can interfere with protein recovery and subsequent analysis. We evaluated the compatibility and reproducibility of protein extractions from laser microdissected human colon mucosa using a subcellular fractionation kit (ProteoExtract, Calbiochem). Four protein fractions corresponding to cytosol (fraction 1), membrane/organelle (fraction 2), nucleus (fraction 3) and cytoskeleton (fraction 4) were extracted, saturation labeled with Cy5 and 5 microg separated by both acidic (pH 4-7) and basic (pH 6-11) 2-DE. The histological stains and fixation required for LMD did not interfere with the accurate subcellular fractionation of proteins into their predicted fraction. The combination of subcellular fractionation and saturation CyDye labeling produced very well resolved, distinct protein spot maps by 2-DE for each of the subcellular fractions, and the total number of protein spots consistently resolved between three independent extractions for each fraction was 893, 1128, 1245 and 1577 for fractions 1, 2, 3 and 4, respectively. Although significant carryover of protein did occur between fractions, this carryover was consistent between experiments, and very low inter-experimental variation was observed. In summary, subcellular fractionation kits are very compatible with saturation labeling DIGE of LMD tissues and provide greater coverage of proteins from very small amounts of microdissected material.

Identification of squamous cell carcinoma associated proteins by proteomics and loss of beta tropomyosin expression in esophageal cancer

AIM: To assess the proteome of normal versus tumor tissue in squamous cell carcinoma of the esophagus (SCCE) in Iranian patients and compare our results with former reports by using proteomics.

METHODS: Protein was extracted from normal and tumor tissues. Two dimensional electrophoresis was carried out and spots with differential expression were identified with mass spectrometry. RNA extraction and RT-PCR along with immunodetection were performed.

RESULTS: Fourteen proteins were found whose expression levels differed in tumor compared to normal tissues. Mass spectrometric analysis resulted in the identification of β-tropomyosin (TMβ), myosin light chain 2 (and its isoform), myosin regulatory light chain 2, peroxyredoxin 2, annexinIand an unknown polypeptide as the down regulated polypeptides in tumor tissue. Heat shock protein 70 (HSP70), TPM4-ALK fusion oncoprotein 2, myosin light polypeptide 6, keratinI, GH16431p and calreticulin were the up-regulated polypeptides found in tumor tissue. Several of these proteins, such as TMβ, HSP70, annexinI, calreticulin, TPM4-ALK and isoforms of myosins, have been well recognized in tumorigenesis of esophageal or other types of cancers.

CONCLUSION: Our study not only supports the involve-ment of some of the formerly reported proteins in SCCE but also introduces additional proteins found to be lost in SCCE, including TMβ.