The sole presence of CDK4 is not a solid criterion for discriminating between tumor and healthy pancreatic tissues

SEER cancer registry biospecimen research: yesterday and tomorrow

The National Cancer Institute's (NCI) Surveillance, Epidemiology, and End Results (SEER) registries have been a source of biospecimens for cancer research for decades. Recently, registry-based biospecimen studies have become more practical, with the expansion of electronic networks for pathology and medical record reporting. Formalin-fixed paraffin-embedded specimens are now used for next-generation sequencing and other molecular techniques. These developments create new opportunities for SEER biospecimen research. We evaluated 31 research articles published during 2005 to 2013 based on authors' confirmation that these studies involved linkage of SEER data to biospecimens. Rather than providing an exhaustive review of all possible articles, our intent was to indicate the breadth of research made possible by such a resource. We also summarize responses to a 2012 questionnaire that was broadly distributed to the NCI intra- and extramural biospecimen research community. This included responses from 30 investigators who had used SEER biospecimens in their research. The survey was not intended to be a systematic sample, but instead to provide anecdotal insight on strengths, limitations, and the future of SEER biospecimen research. Identified strengths of this research resource include biospecimen availability, cost, and annotation of data, including demographic information, stage, and survival. Shortcomings include limited annotation of clinical attributes such as detailed chemotherapy history and recurrence, and timeliness of turnaround following biospecimen requests. A review of selected SEER biospecimen articles, investigator feedback, and technological advances reinforced our view that SEER biospecimen resources should be developed. This would advance cancer biology, etiology, and personalized therapy research. See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology." Cancer Epidemiol Biomarkers Prev; 23(12); 2681-7. ©2014 AACR.

Transfection of a eukaryotic vector expressing a mutant CDK4 up-regulates POLD1 expression in SMMC-7702 cells

AIM: To construct a eukaryotic expression vector encoding a mutant CDK4 protein and to investigate the effect of transfection of this vector on POLD1 expression in SMMC-7702 cells.

METHODS: The mutant CDK4 gene was amplified by RT-PCR from total RNA isolated from the human hepatocarcinoma cell line SMMC-7721, digested, and inserted into the eukaryotic expression vector pEGFP-C1. The resultant recombinant plasmid was confirmed by sequencing. After the recombinant plasmid was transfected into SMMC-7702 cells using Lipofectamine 2000, the expression of fusion protein was observed by fluorescence microscopy, and expression of CDK4 and POLD1 mRNAs was detected by real-time PCR.

RESULTS: The eukaryotic expression plasmid GFP-CDK4 was successfully constructed. The mutant CDK4 gene contained 5 base mutation sites, 4 base insertions and 2 deletions, which caused 7 amino acids to change. Compared to non-tranfected cells or cells transfected with the pEGFP-C1 vector, cell proliferation was significantly higher in cells transfected with the recombinant vector (0.826 ± 0.08 vs 0.596 ± 0.06, 0.609 ± 0.10, F = 7.033, P < 0.05). The expression levels of CDK4 and POLD1 genes in cells transfected with the recombinant vector was significantly higher than those in the two control groups (1.94 ± 0 .11 vs 1.01 ± 0.00, 1.05 ± 0.12, F = 54.046, P < 0.01; 0.54 ± 0.04 vs 0.30 ± 0.07, 0.25 ± 0.06, F = 11.788, P < 0.05). Similar results were also obtained for the protein expression levels of CDK4 (0.65 ± 0.03 vs 0.41 ± 0.03, 0.39 ± 0.05, F = 14.665, P < 0.05) and P125 (0.54 ± 0.04 vs 0.30 ± 0.07, 0.25 ± 0.06, F = 11.788, P < 0.05).

CONCLUSION: Tranfection of the eukaryotic expression plasmid GFP-CDK4 significantly increases the proliferation and invasion of SMMC-7702 cells possibly by up-regulating POLD1 expression.