During the development and progression of cancer, cell nuclei undergo significant structural alterations. Many of these changes are identifiable at the light microscopic level, including increases in nuclear size, deformities in nuclear shape, and changes in the internal organization of the nucleus. Our laboratory has been focused on the understanding of a recently described subnuclear structure, the perinucleolar compartment (PNC), which is physically associated with the nucleolus and is present primarily in cancer cells and transformed cell lines. The PNC is enriched with newly synthesized RNA and RNA-binding proteins and its structure and integrity are dependent upon cellular transcription. These findings suggest that PNCs are involved in transcription and RNA metabolism, both of which are significantly altered during the development of malignancy. Thus, the presence of PNCs represents changes in cell and molecular activities in transformed cells and may be a good indicator for the progression of malignancy. Our goals are 1) to understand the function of PNC in transformed cells, and 2) to examine the correlation between PNC prevalence (percentage of cells that contain one or more PNCs) and the degree of malignant progression in vivo, and to evaluate the possibility of using PNC prevalence as a specific tumor marker.
Over the past year, we began to examine PNC prevalence in a spectrum of normal and cancerous breast tissues in collaboration with a team of pathologists at the Robert H. Lurie Cancer Center, including Drs. Ann Thor, Ritu Nayar, and Elizabeth Wiley, as well as Dr. Borko Jovanovic of the Public Health Department. Preliminary results from over 230 samples showed remarkable differences in the PNC prevalence among normal, benign epithelium hyperplasia, in situ carcinomas, invasive ductal carcinomas with no lymph node involvement, and invasive ductal carcinomas those became metastatic to either lymph node or distant sites. PNC prevalence increases with the clinical progression of the disease. More interestingly, statistical analyses in follow-up case-matched studies showed that samples derived from patients who had recurrence demonstrate a significantly higher PNC prevalence as compared to those from patients who had similar primary diagnosis and did not develop recurrence, suggesting that PNC prevalence impart useful prognostic information. We are currently expanding the sample size to confirm these preliminary results, concentrating on the evaluation of the prognostic value of PNCs not only in breast tissues, also in other tissue types.
Structure and Function of the Nucleolus
The nucleolus is the center for ribosome biogenesis and also is the most prominent nuclear marker for cancer diagnosis. Both ribosome biogenesis and nuclear structure are altered significantly to meet the needs of malignant cells. Therefore, the understanding of both nucleolar structure and function and the regulation of ribosome biogenesis is crucial for the understanding of malignant transformation and for devising appropriate therapeutic strategies. Our group and other laboratories have recently reported that nucleolar factors involved in ribosome synthesis exchange rapidly between the nucleolus and the nucleoplasm in live cells. Such exchanges represent temporal and spatial opportunities for various covalent and non-covalent modifications that might link signal transduction pathways to ribosome synthesis. We are interested in using live cell systems to analyze the essential cis and trans elements that are important in regulating specific ribosome synthesis machinery.
Selected Publications:
Diaz-Perez S., Ferguson, D.O, Wang C., Csankovszki, G, Wang. C., Tsai, SC., Dutta D., Perez, V., Kim SM., Eller C. D., Salstrom J., Ouyang Y., Teitell M.A., Kaltenboeck B., Chess A., Huang S., and Marahrens Y. 2006. A deletion at the mouse Xist gene exposes trans-effects that alter the heterochromatin of the inactive X chromosome and the replication time and DNA stability of both X chromosomes. Genetics. 174:1115-33
Kopp K., Gasiorowski JZ., Chen D., Gilmore R., Norton JT., Wang C., Leary DJ., Chan EK., Dean, DA., and Huang, S. 2007. Pol I Transcription and Pre-rRNA Processing Are Coordinated in a Transcription-dependent Manner in Mammalian Cells. Mol. Biol. Cell.18: 394-403.
Norton, J. T., M.A. Witschi, L. Luong , A. Kawamura, S. Ghosh, M.S. Stack, E. Sim, M.J. Avram, D.H. Appella, and S. Huang. Synthesis and anti-cancer activities of 6-amino amonafide derivatives. Anti-Cancer Drugs. 2008. 19(1):23-36
Norton J.T., C.B. Pollock, C. Wang , J.C. Schink, J.J. Kim, and S. Huang. 2008. Perinucleolar Compartment Prevalence is a Phenotypic Pan-Cancer Marker of Malignancy. Cancer. 113: 861-869.
Wang, C., J.T. Norton, S. Ghosh, J. Kim, K. Fushimi, J.Y. Wu, M.S. Stack, and S. Huang. 2008. PTB Differentially Affects Malignancy in a Cell Line Dependent Manner. J. Biol. Chem. 283: 20277-87.
Slusarczyk A. and S. Huang. 2008 The perinucleolar Compartment (PNC): Detection by Immunohistochemistry. Methods in Molecular Biology-The Nucleus. Editor: Ron Hancock, Humana Press.
Norton J.T., Wang, C., Gjidoda, A., Henry, R.W., and S. Huang. 2009. Perinucleolar compartment is directly associated with DNA. J. Biol. Chem. 284: 4090-4101.
Pollock, C. and S. Huang. 2009. The Perinucleolar Compartment. 2009. J. Cell. Biochem. 15;107(2):189-93.
Norton, J. T., Steven A. Titus S. A., Dexter D., Austin C., Zheng W., S Huang 2009. Automated High Content Screening for Compounds That Disassemble the Perinucleolar Compartment, J. Biol. System.
