Date of Award


Degree Name

Biological Sciences


College of Science

Type of Degree


Document Type


First Advisor

Guo-Zhang Zhu

Second Advisor

Elmer Price

Third Advisor

Simon Collier


In the U.S., breast cancer comprises about 30% of all cancer cases (excluding skin cancer) in women. Such a high incidence makes breast cancer a significant health concern, but our understanding of the molecular and cellular mechanisms of this disease is still limited. Growing evidence suggests that the development of human breast cancer may involve epigenetics, which attributes changes in phenotype to mechanisms other than changes in the DNA sequence itself. Histones as the chief proteins of chromatin work on gene expression, and methylation of histone 3 lysine 4 (H3K4) results in transcriptional activation. Lately, Paired box (Pax) trans-activation domain-interacting protein (PTIP), part of the H3K4 methyl-transferase complex, has been identified as a novel regulator of histone methylation. In this study, we hypothesize that PTIP plays a role in the epigenetic regulation of breast cancer cell growth. Two human breast cancer cell lines MCF-7 (adeno carcinoma) and T47D (ductal carcinoma) are used in this study. To test our hypothesis, we have first determined the PTIP mRNA expression level in MCF-7 and T47D cells by reverse transcription-polymerase chain reaction (RT-PCR) and the PTIP protein level by Western blot. We have also determined PTIP’s sub-cellular localization in MCF-7 and T47D cells by immunofluorescence assay. In addition, we have knocked down and over-expressed PTIP. In other words, we reduced and increased the expression of PTIP in MCF-7 and T47D cells through siRNA (small interference RNA) and ectopic over-expression respectively. We then examined the effects of PTIP knockdown and PTIP over-expression on MCF-7 and T47D cell growth. As a result, we found that PTIP knockdown in MCF-7 cells results in an increase of cell proliferation. The information collected from this study will allow us to comprehend PTIP’s role in breast cancer cell growth and contribute to our understanding of the epigenetic basis of human breast cancer.


Breast - Cancer - Research.