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The nuclear matrix has been linked to several important cellular functions within cells, such as DNA organization and replication, as well as regulation of gene expression. It has been reported that the nuclear matrix protein composition is altered in cells grown on different extracellular matrices in vitro. This study examined the nuclear matrix protein composition of tumors produced by MAT-LyLu (MLL) rat prostate tumor cells implanted at different organ sites within the rat. When high resolution two-dimensional gels were utilized to compare nuclear matrix protein composition to the prostate orthotopic tumor, it was found that there were distinct protein differences depending upon where the tumor grew. In particular, there were 14 proteins found in the lung, six proteins found in intramuscular, 17 proteins is the heart, and five proteins in the tail vein tumor tissue that were not present in the prostate orthotopic tumor tissue. Therefore, this study adds evidence to support that the nuclear matrix composition of a cell is dependent, at least in part, by the extracellular matrix and/or different cellular environments and may have a role in site-specific differences in tumor properties.

The progression of normal squamous epithelium to a malignant metastatic phenotype may depend on cellular genetic events and the failure of host mechanisms. Intermediate biomarkers are needed to more effectively identify and quantify malignant progression and develop the potential for specific treatments and prevention strategies. The nuclear matrix is the RNA-protein scaffold of the nucleus, which controls in part nuclear shape, DNA organization, and DNA function. Nuclear matrix proteins in all previously studied cell types show a common set of nuclear matrix proteins and a subset of tissue- and cell type-specific proteins. In every system studied to date, the nuclear matrix has been demonstrated to undergo quantifiable alterations in its protein composition with transformation to the malignant phenotype. The loss and gain of nuclear matrix proteins are being investigated as biomarkers for malignant transformation in breast, colon, and prostate carcinoma. We have investigated nuclear matrix protein composition in laryngeal and oral cavity primary squamous cell tumors and metastatic cervical lymph nodes. Laryngeal carcinoma demonstrated the gain of two specific nuclear matrix proteins in comparison with noncancerous squamous epithelium. Squamous cell carcinoma matrixes demonstrate greater heterogeneity than do previously studied adenocarcinoma matrixes, and yet they display specific matrix proteins that may represent important potential biomarkers.