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Quantitative correlation between cellular proliferation and nuclear poly (ADP-ribose) polymerase (PARP-1)
Ernest Kun1, Eva Kirsten, Pal I Bauer
1Department of Anatomy, School of Medicine, University of California San Francisco Medical Center, San Francisco, CA 94143, USA.
International Journal of Molecular Medicine
|January 5, 2006
Summary
Poly (ADP-ribose) synthetase (PARP-1) activation and DNA synthesis are key diagnostic signals for cancer cells. Inhibiting PARP-1 affects DNA synthesis in intact cancer cells, highlighting its role in cancer progression.
Area of Science:
- Biochemistry
- Molecular Biology
- Cancer Research
Background:
- Poly (ADP-ribose) synthetase (PARP-1) is a crucial enzyme involved in DNA repair and genomic stability.
- Understanding the regulation and activity of PARP-1 in different cellular states, particularly in cancer, is vital for developing diagnostic and therapeutic strategies.
Purpose of the Study:
- To develop a method for separating and assaying PARP-1 and DNA synthetase activities.
- To compare PARP-1 activity and DNA synthesis rates in non-malignant and cancer cells.
- To investigate the role of PARP-1 in cancer cell proliferation and DNA synthesis.
Main Methods:
- Cells were treated with lysophosphatidyl choline and subjected to centrifugal extraction to isolate PARP-1 and DNA synthetase activities.
- Poly (ADP-ribose) synthesis was assayed using short end-blocked dsDNAs and spermine as coenzymes.
- PARP-1 activity and DNA synthesis rates were compared between non-proliferating non-malignant cells and proliferating cancer cells.
- The effect of PARP-1 inhibitors and inactivators on DNA synthesis was assessed in intact and permeabilized cancer cells.
Main Results:
- A system was established to assay PARP-1 activity, with maximal activation observed with short dsDNAs and spermine.
- Rates of poly (ADP-ribose) and DNA synthesis were highest in pre-confluent non-malignant cells and proliferating cancer cells, and lowest in contact-inhibited non-malignant cells.
- Cancer cells exhibited extensive auto-poly (ADP)-ribosylation, strongly inhibited by ATP, unlike non-malignant cells.
- PARP-1 activation and DNA synthesis were identified as significant diagnostic markers for cancer cells.
- PARP-1 inhibitors reduced DNA synthesis in intact cancer cells, but not in permeabilized cells.
Conclusions:
- PARP-1 activity and DNA synthesis are significantly elevated in cancer cells, serving as potential diagnostic markers.
- The regulation of PARP-1 activity, particularly auto-poly (ADP)-ribosylation, differs between malignant and non-malignant cells.
- PARP-1 plays a critical role in maintaining DNA synthesis in cancer cells, as evidenced by the inhibitory effects of PARP-1 targeted drugs.