One of the reasons for tumor uncontrolled growth is that cancer cells are almost invisible for immune system. For patient’s organism successful fight against the tumor, scientists try to make the tumor “visible” – to mark its surface with antigens causing explosive immune response. Such modified cancer cells could serve as a vaccine for an ordinary, non-modified tumor, because then activated immune system will inhibit tumor growth. Scientists from RAMS Science Hematology Centre have attempted to develop such antitumor vaccine. As an antigen that whips immune system, the researchers have used a protein of Newcastle disease virus coating.
Newcastle disease is a serious bird disease, which is impossible to cure. When this disease, also known as Asiatic cholera, appears on a bird farm, all livestock has to be killed. Newcastle disease virus is a strongest stimulant for mammalian immune system. In order to develop antitumor vaccine the scientists have chosen a viral coat protein, hemagglutinin neuraminidase (HN). They have inserted HN-containing constraint to mice myeloma cells and got the cell line that synthesizes viral protein. This line was used as a vaccine. The cells were first irradiated with radioactive Cs (to prevent vaccine tumor from growing in the organism) and then introduced intraperitoneally to mice. Other animals were given injections of irradiated, but non-modified, tumor or tumor, infected with intact Newcastle virus. Each mouse has received one million cells. After three days, the original tumor was transplanted under the skin between the shoulders of every mouse (4000 thousand cells of mice myeloma) and has been observed and measured for 21 day. The researches have chosen this period because then animals start suffering from tissue necrosis and ulceration. Then the tumor was pulled out and weighed. Íàïðàñíî ìó÷èòü ìûøåé
Organisms of mice, which were preliminary immunized with HN-containing tumor, were desperately fighting myeloma growth. The tumor weight was 3-15 times lower than that of mice vaccinated with ordinary tumor or culture medium. Intact Newcastle disease virus doesn’t stop tumor growth, and sometimes even worsens the situation. And hemagglutinin neuraminidase is just what the doctor ordered. According to the scientists, introduction of this gene to the tumor led to development of the vaccine, effective and safe for the patient. This constraint can by used to modify any tumor, not only myeloma. Unfortunately, immunotherapy is effective for curing only small tumors, thus this vaccine is effective only during early stages of the disease.