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Ribonucleotide reductase M2 subunit (RRM2) is one of the two subunits of human ribonucleotide reductase which plays a critical role in tumor progression. The aim of the present study was to analyze its expression, clinical significance and biological functions in gastric adenocarcinoma. We observed the upregulation of RRM2 mRNA and protein in all nine gastric cancer cell lines examined. In paired primary gastric cancers, both mRNA and protein levels of RRM2 were significantly upregulated in tumors compared with the corresponding non-tumorous gastric tissues. RRM2 protein expression correlated with higher tumor grade, advanced T stage and poor disease-specific survival. RRM2 knockdown in gastric cancer cell lines AGS, MKN1 and MKN28 significantly suppressed cell proliferation, inhibited monolayer colony formation, reduced cell invasion and induced apoptosis. Downregulation of RRM2 suppressed xenograft formation in vivo. Collectively, these findings suggest that RRM2 plays a crucial role in gastric tumorigenesis and may serve as a potential prognostic marker and therapeutic target in gastric cancer.

Four melanoma cell lines with different metastatic potential were used to study the expression of 67 kD laminin receptor (LnR) gene by traditional immunohistochemistry and polymerase chain reaction techniques. Intensive labeling of LnR protein was found in cells with high metastatic potential. Also, the result from PCR and RT-PCR proved the correlation between LnR gene and metastatic potential of melanoma cells in addition to other cell types from previous studies. It is, thus, suggested that the expression of LnR gene can be used as an early marker for the malignancy of melanoma cells.

Nuclear matrix is a scaffold-like structure of the nucleus after sequential treatments with detergents, DNase, and high salt buffers. Its involvement in various cellular activities has been emphasised in various studies. In this study, nuclear matrix of two human nasopharyngeal carcinoma cell Lines were compared and analysed in terms of their morphological appearance and electrophoretic patterns of proteins. The stability of nuclear matrices against enzymatic digestion was found to be similar in these two cell lines. However, cell line specific nuclear matrix proteins were detected in each cell line. The significance of these proteins in cellular function and oncogenesis will be investigated in due course.

Carcinoma of uterine cervix is closely associated with human papillomavirus (HPV) infection and HPV16 DNA has been shown to integrate into the genome of host cancer cells. The subgenomic fragments (E6E7) were found to be present in nuclear matrix (NM)-associated DNA by novel PCR. Further investigation showed the absence of E6 open reading frame (protein encoding sequence) in NM-associated DNA. DNA-protein binding assay (Southwestern blotting) labeled 2 groups of NM proteins that bound commonly to E6E7 DNA and specifically to either E6 or E7 DNA. Complex protein formation that was recognized by E6E7 was suggested. Further investigation into properties of these NM proteins may provide a better understanding of the role of HPV in cervical carcinogenesis.