What Is a Grawitz Tumor?

Nude Mouse (Nude Mouse) has become an indispensable experimental animal model in the field of medical biology research. It is a mutant mouse with congenital thymus defect, which is formed by homozygosity of the naked locus gene in the VIII linkage group ^[1] . In particular, it has special value in oncology, immunology, safety evaluation of drugs and biological products, and screening of effective drugs. The reason why nude mice can become experimental models with great potential in scientific research is because of the unique genetic characteristics of the nu gene. Through the efforts of experimental animal genetic breeders in various countries around the world, the nu gene has been introduced into different inbred animals and has become a series of animal models. There is only one mouse model. Because they have different genetic backgrounds and genetic characteristics of the nu gene, medical biology researchers have obtained an extremely valuable experimental material.

Nude mice suffer from athymic, T-lymphocyte deficiency, low resistance, and often die from wasting diseases. ^[2]

In 1962, Grist, a hospital in Glasgow, England, accidentally found individual hairless mice in non-inbred mice. Four years later, Flanagan at the Edinburgh Zoological Institute confirmed that the hairless mice were caused by

The main feature of nude mice is hairless ^[3]

Nude rats are currently mainly used in human cancer transplantation studies. Nude rats have no thymus and lack T cells, so they can successfully transplant heterogeneous skin and heterogeneous tumors, including mouse tumors and human tumors. Festing first reported xenograft tumors (human colon cancer and mouse plasmacytoma) in nude rats, but spontaneous regression after growth of the transplanted tumor. Since then, there have been reports of transplantation of human cancer cell lines and surgical specimens in nude rats. Human cancer transplantation in nude rats is the most commonly used subcutaneous route, and it is also useful in intrarenal and intramuscular muscles. Transplanted human tumors that can grow in nude rats include melanoma, malignant glioma, and cancers of the colon, pancreas, lung, breast, kidney, prostate, vulva, and cervix. Most human cancers resolve spontaneously after transplantation, and only a few tumors grow progressively. Colston reported nine human cancer cell lines, seven successfully transplanted, and only one melanoma showed progressive growth without spontaneous regression. Stragand reported that two human colon cancer cell lines were successfully transplanted, but only the Lovo cell line was growing progressively. After the successful transplantation of another SW620, 90% of the nude rats showed spontaneous tumor regression. Williams transplanted 5 human urogenital tumor cell lines into nude rats, 3 of which were successful, and only 1 kidney cancer did not regress spontaneously. The reason for its spontaneous regression is not very clear, and it is speculated that it is related to the immune function mediated by T cells in nude rats, especially the strong activity of NK cells. However, some authors believe that the reason for the spontaneous regression may be related to the older age of the nude rats, and the selection of young nude rats at 4 weeks of age may improve the success rate of transplantation.

Recently, the Liver Cancer Institute of Zhongshan Hospital in China successfully established nude rat human liver cancer models LTNR1 and LTNR2. This is the first report of a nude rat human liver cancer tissue model. They also reported on human cancer transplantation studies in nude rats. Please refer to the literature in Chapter Nine, Section IV of this book. LTNR1 and LTNR2 were obtained from nude mouse human liver cancer tissue models LTNM4 and LTNM3, respectively. The average age of nude rats is 31.5 (9-49) days, and the subcutaneous transplantation method is adopted. Pathological and AFP tests have confirmed the success of human liver cancer transplantation in nude rats. Both models have the following characteristics: The morphological and functional characteristics of the original human hepatocellular carcinoma are retained. Both LTNR1 and LTNR2 are equally differentiated (grade II-III) hepatocellular carcinoma. LTNR1 has a higher AFP concentration, with a median concentration of 8000ng / ml: LTNR2 has a lower concentration, which does not exceed 125ng / ml. Retained some advantages of human liver cancer models LTNM4 and LTNR3 in nude mice: high success rate of subculture transplantation, LTNR1 and LTNR2 were 100% (65/65) and 87.5% (14/16); low spontaneous regression rate, 3.1 % (2/65) and 0 (0/14); short incubation period, 12.7 ± 3.9 days and 17.0 ± 6.2 days; tumor growth was rapid, with an average weekly average diameter increase of 9.1 ± 2.7 mm and 8.8 ± 3.4 mm. It has the advantages of large tumor production and large blood volume, which makes it easier to perform some small surgical operations. At present, these models have been used to explore tumor markers, test positive scans, and experimental treatments, and have achieved preliminary positive results.

The establishment of nude rat human liver cancer model not only benefits the research of human liver cancer, but also brings new hope to various human cancer transplantation. The establishment of a nude mouse human cancer model can make up for some of the shortcomings of nude mouse human cancer model and better promote the progress of tumor research.

Nude mice and humans have similar immune systems, including B cells and T cells, where Bc is a humoral immune cell from the bone marrow; Tc is a cellular immune cell from the thymus. The significance of research on athymic nude mice lies in the fact that the antibody-free individuals deal with viruses and cancer, and have made important contributions to the development of human medicine and science.