In 1936, biologist John Bittner studying group of mice discovered breast cancer in the family. During the following years, cancer linked to a virus called mouse mammary tumour virus (MMTV). 2 This virus is a B-type retrovirus (“Retroviruses are responsible for certain cancers and slow virus infections of animals and cause at least one type of human cancer 1). Unlike most organisms, the retrovirus consist of RNA (Ribonucleic acid – “is a nucleic acid polymer consisting of nucleotide monomers, which plays several important roles in the processes of translating genetic information from DNA into proteins” 5) instead of DNA (Deoxyribonucleic acid – “is a nuclei acid that contains the genetic instructions used in the development and functiong of all known living organisms – 4). 3 The retrovirus uses the RNA as master pattern to form DNA, the genetic material that puts viral replication instructions or reverse transcription, the opposite of normal flow of genetic information in living things. As a result malignant tumors and other disorders develop. 6
Scientists are aware MMTV cause breast cancer in rodents, also produce and spread in human breast cells. In Britain ten percent of breast cancer link to genetic and environmental factors, however ninety percent of cases less known, but MMTV ‘rapidly spreads’ in cultured breast cancer. In the laboratory, AZT (zidovudine) an HIV (Human immunodeficency virus 7) drug can stop the replicating of mouse mammary tumor virus. Researchers at the University of veterinary medicine in Viena, (Viennese Christian – Doppler – Laboratory for Gene Therapeutic Vector Development 10) said: “Despite the widely accepted belief that human cells are not an appropriate host of MMTV, ours data demonstrate the productive infection of human breast cells.” This finding might help to explain the presence of MMTV – like sequences in at least a certain proportion of human breast cancers.” 8 The results of the research study published “Cancer Research” Journal (August 2005). The laboratory findings link MMTV to human cells discovered by Dr. Stanislav Indik (Czech born scientist) confirmed when MMTV carrying an inserted fluorescence gene. Under the microscope the infected cells seen clearly by the fluorescent light source, proof of successful infection. British scientist Professor Walter H. Gonzburg, Ph.D., Head of the Christian – Doppler – Laboratory said: “Even if MMTV turns out not to cause breast cancer in humans, the data are also exciting for a completely different reason since MMTV can also be engineered as a means of efficiently delivering therapeutic genes” or provide Trojan horse treatment for breast cancer. Also, Dr. Gonzburg said: “In order to confirm this casual connection scientifically, further research is still necessary.” 10
Reported in July 2004 (Online edition of CANCER 11), Dr. Paul Levine and colleagues from The George Washington University School of Public Health discovered through sampling of tissue samples from breast cancer patients in Europe, north and South America and North Africa, link to mouse mammary tumour virus. The results of the samples tested: Patients in Tunisia showed 74% link to MMTV, Australia 42%, Italy 38%, Argentina 31% and United States 36%. Also, Vietnamese woman breast cancer samples linked less than one percent to MMTV. The researchers said: “The geographic differences were compatible with studies of MMTV in wild mice”, (“MMTV may spread by a species of house mouse that is extremely common in North Africa but less so in the U.S. Studies show that some colonies of these mice are commonly infected with MMTV”. 11), However the test measured only a small sample of breast cancer patients. 9
Researchers at the University of Munich, Germany suggested (Reported in the June 2006 issue of Medical Hypothesis) dogs might transmit mouse mammary tumour virus (MMTV) (as well as other microbes) to carcinogenesis in humans, particularly (hypothesizing) link to breast cancer in Western countries and its correlation with higher standard of living. The researchers studied 69 women with breast cancer. They found 26 patients (37%) had a dog at the time of consultation and throughout the previous ten years. Also, eleven patients kept a dog some time during the past ten years and sixteen patients had intensive contact with dogs. 12 The researchers discovered women from Eastern countries increased risk of breast cancer when they moved to Western nations – Oriental or Asian women rarely keep dogs as pets.13 Also, reported two patients had received dog bites. “Taken together, 79.9% of all patients had intensive contact with dogs before the diagnosis of breast cancer, encompassing a time period up to 30 years.” Regarding keeping a cat as a pet revealed no significant difference link to breast cancer. Researchers theorize the route of transmission of MMTV to human cancer: “With dogs noses often close to the ground, they may inhale infectious excretions from small animals such as mice and could pass along viruses to their human owners without succumbing to cancer themselves, although the group points out that breast cancer occurs frequently in dogs.” 12 Also, another study in Norway confirmed the research findings in Munich, reported – “53.3 per cent – of breast cancers in 14,401 dogs.” 14 However, Kat Arnery, MD, information Officer for Cancer Research in London contradicts the study results. She commented: “There is currently no scientific evidence to support the suggestion that women can get breast cancer from contact with dogs. This study was very small and does not take other factors in account.” Also, Sarah Rawlings from Breakthrough Breast Cancer in London commented researchers had not proven a virus infected the dogs. 12
References:
1) retrovirus – http://www.britannica.com/eb/article-9063323/retrovirus
2) Is a virus causing breast cancer? – http://www.newscientist.com/channel/health/mg19426061.400-is-a-virus-causing-breast-cancer.html
3) THE INHERITED BREAST CANCER VIRUS – http://www.autoimmune.com/HMTVGen.html
4) DNA – http://en.wikipedia.org/wiki/DNA
5) RNA – http://en.wikipedia.org/wiki/RNA
6) Retrovirus – http://encarta.msn.com/encyclopedia_761561203/Retrovirus.html
7) HIV – http://en.wikipedia.org/wiki/HIV
8) Mice ‘could give cancer to humans’ – http://www.metro.co.uk/news/article.html?in_article_id=69709&in_page_id=34
9) Virus ‘linked to breast cancer’ – http://news.bbc.co.uk/1/hi/health/3879783.stm
10) Mouse virus causing mammary cancer found to infect human cells – http://www.medicalnewstoday.com/articles/28835.php
11) Study links virus to aggressive breast cancers – http://www.eurekalert.org/pub_releases/2004-07/jws-slv070704.php
12) Could Dogs Pose a Risk Factor for Breast Cancer? – http://www.medscape.com/viewarticle/537495
13) Dogs may give women breast cancer? – http://newsfromrussia.com/science/health/31-10-2007/99903-dogs_cancer-0
14) Can dogs give your breast cancer? Bizarre medical theories that experts claim may actually be true –
http://www.dailymail.co.uk/pages/live/articles/health/healthmain.html?in_article_id=490581&in_page_id=1774&ito=1490
