Investigating MMTV-Like Sequences in Pakistani Human Tissues: A PCR Analysis

1. Abstract Objectives Materials and Methods Epidemiological Profile PCR Analysis Preliminary Studies Characterizing the Prevalence of Mouse Mammary Tumor-Like Sequences in Human Tissues of Pakistani Origin Saira Amir, Samina Bilal, Waqar Ahmed, Muniza Zahid, and Farah Mustafa.Department of Biosciences, COMSATS Institute of Information Technology, Islamabad, Pakistan MMTV in Pakistani Wild Mice Pakistan has the second highest rate of breast cancer in Asia after Israel with nearly 1 out of 9 women at risk of developing breast cancer at some stage in their lifetime. A potential role of viruses in human breast cancer induction/development is increasingly coming to surface. Several different groups around the world have demonstrated the presence of mouse mammary tumor virus (MMTV)-like sequences in tumor but not normal breast tissue. However, these findings are controversial and seem to differ depending upon the geographic location and ethnicity of a population. No such work has been conducted in South Asia. Towards this end, preliminary PCR-based studies were conducted on breast cancer patients and normal individuals in Pakistan. Single PCR screening of collected blood and breast cancer samples from the local population gave sporadic, mostly weak positive results. However, nested PCR of a subset of the samples from normal and cancer patients revealed that for the pol region, over 50-100% of the samples were positive, for env 15-75% of the samples were positive, while for long terminal repeat (LTR) 5-100% of the samples were positive, depending upon whether they were from blood or breast tissue. Sequencing of the PCR fragments further revealed these sequences to be 90-100% homologous to Mtv-8 but not HERV-K, thus identifying these amplified bands to be of MMTV origin. Finally, test of the wild Pakistani Mus musculus revealed that they contain endogenous MMTVs very similar to Mtv-8. Together, these unexpected results suggest that the Pakistani population may be exposed to MMTV, maybe through zoonotic transmission from mice. These observations need further stringent study and confirmation. Differential expression studies are in the process as well as hunt for viral integration sites. It is only with a positive demonstration of integration sites in normal individuals that one can definitively prove whether MMTV is actually in the human population. Nested PCR to Increase Sensitivity & Specificity Sequence Analysis Conclusions • Test whether the Pakistani population exhibits MMTV-like sequences in their blood, tumor and/or non-tumor cells • If so, are the sequences present only in the breast cancer patients or normal healthy population as well • Differentiate whether the sequences observed are of MMTV or HERV-K origin • Access whether the wild type Mus musculus mouse species of Pakistan actually harbors MMTV or not as a potential zoonotic source of MMTV in the human population This work was conducted as part of the MS Thesis requirement of Ms. Saira Amir