Regulatory mechanisms that are clearly different between non-malignant and malignant cells can potentially be exploited as new targets for the early detection and treatment of malignancy. For the last few years the PI has been extensively characterizing a multiprotein complex isolated from human cells which is capable of mediating DNA replication in vitro. She was the first to successfully isolate and characterize the intact mammalian multiprotein DNA replication complex (termed the DNA synthesome) from a variety of mammalian cell lines and tissues and demonstrated that it is stable and fully functional. Recent data indicate that the transformation of a non-malignant human breast epithelial cell to a malignant state is accompanied by a significant alteration of a specific protein component of the synthesome, namely, proliferating cell nuclear antigen (PCNA). She has determined that it arises not because of a genetic mutation, but through an epigenetic mechanism. In normal breast cells PCNA is poly(ADP)-rybosilated, while in breast cancer cells and tissues the majority of PCNA molecules are free of this post-translational modification. Furthermore, she has been able to detect the non-rybosilated form of PCNA in the sera of breast cancer patients, prompting her to hypothesize that the non-rybosilated form of PCNA may be useful as a diagnostic marker for breast cancer. Another critical observation is that the synthesome isolated from breast cancer cells has a significantly decreased DNA replication fidelity, exhibiting a more error-prone replication process than the complex purified from non-malignant breast epithelial cells. This was the first direct experimental evidence indicating that the DNA replication machinery of breast cancer cells is, in itself, mutagenic. To date there has been a 100% correlation between the observed decrease of DNA replication fidelity and the non-rybosilation of PCNA in malignant breast cells and tissue. Dr Malkas data strongly suggest that the specific alteration of PCNA and the decreased replication fidelity in breast cancer cells are linked and may be hallmarks of breast cell malignancy. She proposes now to fully characterize the specific alteration of PCNA (both structurally and mechanically), which distinguishes the non-malignant and the breast cancer cell DNA synthetic apparatus from one another. This project has the unique potential to provide significant insight into the process(es) whereby tumor cells can override some of the control signals which regulate DNA replication fidelity in non-malignant cells and contribute to the emergence of a mutagenic DNA replication.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Pathology B Study Section (PTHB)
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Spalholz, Barbara A
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Indiana University-Purdue University at Indianapolis
Internal Medicine/Medicine
Schools of Medicine
United States
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Dai, Heqiao; Liu, Jianying; Malkas, Linda H et al. (2009) Chromium reduces the in vitro activity and fidelity of DNA replication mediated by the human cell DNA synthesome. Toxicol Appl Pharmacol 236:154-65
Novotny, Nathan M; Grosfeld, Jay L; Turner, Katharyn E et al. (2008) Oxidative status in neuroblastoma: a source of stress? J Pediatr Surg 43:330-4
Kyselova, Zuzana; Mechref, Yehia; Kang, Pilsoo et al. (2008) Breast cancer diagnosis and prognosis through quantitative measurements of serum glycan profiles. Clin Chem 54:1166-75
Sandoval, John A; Turner, Katharyn E; Hoelz, Derek J et al. (2007) Serum protein profiling to identify high-risk neuroblastoma: preclinical relevance of blood-based biomarkers. J Surg Res 142:268-74
Sandoval, John A; Grosfeld, Jay L; Hickey, Robert J et al. (2006) Structural analysis of the human neuroblastoma DNA replication complex: insights into faulty proliferation. J Pediatr Surg 41:266-70
Sandoval, John A; Dobrolecki, Lacey E; Huang, Jeffrey et al. (2006) Neuroblastoma detection using serum proteomic profiling: a novel mining technique for cancer? J Pediatr Surg 41:639-46; discussion 639-46
Sandoval, John A; Hoelz, Derek J; Woodruff, Heather A et al. (2006) Novel peptides secreted from human neuroblastoma: useful clinical tools? J Pediatr Surg 41:245-51
Sandoval, John A; Hickey, Robert J; Malkas, Linda H (2005) Isolation and characterization of a DNA synthesome from a neuroblastoma cell line. J Pediatr Surg 40:1070-7
Escobar, Mauricio A; Hoelz, Derek J; Sandoval, John A et al. (2005) Profiling of nuclear extract proteins from human neuroblastoma cell lines: the search for fingerprints. J Pediatr Surg 40:349-58
Yang, Jin; Chen, Zhiwen; Liu, Yang et al. (2004) Altered DNA polymerase iota expression in breast cancer cells leads to a reduction in DNA replication fidelity and a higher rate of mutagenesis. Cancer Res 64:5597-607

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