Abstract:
Breast cancer is the most common cancer in females and leading cause of cancer related
deaths in females worldwide. Breast cancer is more common in developed countries as
compared to developing countries. Even though Pakistan lies in the region of low
prevalence of breast cancer there is substantially higher rate reported as compared to its
neighbors. The known risk factors of breast cancer include mutations in P53 gene
BRCA1 and BRCA2 genes, hormonal factors and lifestyle based factors. As reported for
other cancers viral etiology of breast cancer is also suspected. Mammary tumors in mice
are also caused by virus known as Mouse Mammary Tumor Virus (MMTV).
The search for human homolog of MMTV gained direction when highly specific MMTV
DNA sequences were shown to be present in human breast cancers. Different levels of
association are reported from different regions of the world however there is no
consensus on whether they present any risk to humans in regard with breast cancer or not.
We hypothesized that among other risk factors viral infection may also contribute to
development of breast cancer. In order to study the prevalence of MMTV-like sequences
we collected blood and formalin fixed paraffin embedded breast cancer samples from
Pakistan. We extracted the DNA and samples confirmed for DNA integrity by
amplification of β-globin gene fragment. At the same time we also obtained tissue and
blood sample from mouse to compare the two samples. MMTV sequences amplified
from mouse were cloned into TA vector and sent for sequencing. While human breast
cancer samples still need to be screened for prevalence of MMTV sequences
