CANCER PROGRESSION OBSERVATION INDEX GENE GROUP AND METHOD OF DETECTING THE GENE GROUP

Provided are a cancer progression observation index gene group and a method of detecting the gene group. The gene group includes cancer progression observation index genes increased or decreased when high- or low-dose radiation is performed on a mouse in which an oncogene is inserted into a thymocyte, for example, Itgb3 and Igf1 increased due to low-dose radiation to suppress the conversion of the thymocyte into a cancer cell, and Itga4, Itgb1, Itgav, Itga6, Itgb4, Raf, Myc, Fos, Trp53 and Apaf1 decreased due to high-dose radiation to stimulate the conversion of the thymocyte into a cancer cell. The gene group and the method may be used to clearly define a cancer progression observation index specifically responding to radiation.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms. The following embodiments are described in order to enable those of ordinary skill in the related art to embody and practice the present invention.

With reference to the appended drawings, exemplary embodiments of the present invention will be described in detail below. To aid in understanding the present invention, like numbers refer to like elements throughout the description of the figures, and the description of the same elements will be not reiterated.

Hereinafter, a cancer progression observation index gene group detected from a mouse exposed to ionizing radiation constituted as described above will be described in detail with reference to the accompanying drawings.

FIG. 1is a flowchart of detecting a cancer progression observation index gene group detected from a mouse exposed to ionizing radiation according to an exemplary embodiment of the present invention.

Referring toFIG. 1, the process includes preparing a plurality of AKR/J mice in which an oncogene is inserted into a thymocyte (S11), dividing the AKR/J mice into a first group subjected to high-dose ionizing radiation, a second group subjected to low-dose ionizing radiation, and a third group not subjected to ionizing radiation (S12), performing high-dose ionizing radiation on the first group of the AKR/J mice, and low-dose ionizing radiation on the second group of the AKR/J mice (S13), obtaining a thymus of a dead mouse of the first or second group of the AKR/J mice and diagnosing cancer when a weight of the thymus is increased to twice or more that before radiation (S14), extracting thymuses by sacrificing the first to third groups of the AKR/J mice at the time at which the third group of the AKR/J mice initially die (S15), and selecting only a thymocyte having no change in weight compared to the organs of the same-aged non-irradiated AKR/J mice from the extracted organs and obtaining DNA recovery, a DNA damage signal, a cell cycle, a cancer progression observation index, a p53 signal system transduction pathway, and apoptosis T- and B-cell activation gene profiles through gene analysis (S16).

Hereinafter, the method of detecting a cancer progression observation index gene group according to the exemplary embodiment of the present invention described above will be described in further detail.

First, in S11, AKR/J mice in which thymic carcinoma naturally occurs according to time due to a mouse leukemia virus gene fragment inserted into a thymocyte chromosome DNA are prepared.

The AKR/J mice used in the test are 6-week old females manufactured by SLC, Japan.

Such AKR/J mice are divided into three groups, and in S13, the first group is subjected to high-dose ionizing radiation, the second group is subjected to low-dose ionizing radiation, and the third group is raised without radiation.

For high-dose ionizing radiation to the first group, gamma rays (Cs-137) are radiated at a dose of 0.8 Gy/min to have a final dose of 4.5 Gy using a gamma ray generating device (IBL 147C, CIS bio-international, France).

In addition, the second group is irradiated to have an accumulated dose of 4.5 Gy in an environment in which gamma rays (Cs-137) having a low dose of 0.7 mGy/hr are radiated, and the third group of the AKR/J mice are raised in a general environment in which no radiation is applied.

Afterward, in S14, when the AKR/J mice included in the first to third groups die during S13, thymuses are obtained from the dead mice by autopsy.

Here, when a weight of an obtained thymus is twice or more an average weight of a thymus of the same aged other AKR/J mouse which is not irradiated, it is determined that thymic carcinoma occurs.

FIG. 2is a graph showing an accumulated value of dead mice caused by the occurrence of thymic carcinoma in each test group on a percentage basis.

Referring toFIG. 2, it can be seen that the second group of the low-dose irradiated mice have lower occurrence of thymic carcinoma than the first group of the high-dose irradiated mice.

Afterward, in S15, based on the time at which the third group of the AKR/J mice initially die, all of the AKR/J mice are sacrificed, and a thymus is obtained from each AKR/J mouse.

The third group of the AKR/J mouse raised in a general environment also have a cancer-occurring gene inserted into a thymocyte, and die after a predetermined time because of thymic carcinoma. Experimentally, it was found that the first mouse died after 150 days of the experiment.

The process in which the thymic carcinoma occurs is fixed to prevent interference of confounding variables.

Afterward, in S16, only thymuses having no weight change of the obtained thymuses are immersed in liquid nitrogen, and gene analysis is performed.

Here, the gene analysis method includes crushing a thymocyte of the obtained AKR/J mouse and performing detection using a microarray kit manufactured by Agilent, and thus is used to analyze expression of a cancer progression observation index genes which are expressed increased or decreased by a factor of two or more in the second group subjected to low-dose radiation.

Table 1 shows digitization of relative change in genes of a mouse in the second group subjected to low-dose radiation when a chip is scanned after the microarray test, compared to genes of a non-irradiated mouse of the second group. Here, it can be confirmed that, for Igf, a ratio to non-irradiation is increased by a factor of 2.1, and for Itgb3, a ratio to non-irradiation is decreased by a factor of 0.2.

FIG. 3is a diagram of an expression mechanism of cancer progression observation index genes in a low-dose irradiated AKR/J mouse which have an influence on the occurrence of cancer.

Referring toFIG. 3, progression of the thymocyte into which a gene initiating the occurrence of cancer is inserted to cancer is suppressed in the low-dose irradiated AKR/J mouse. This is because the death of a cancer cell is induced according to a decrease in an Itgb3 gene in the cancer-progressing cell.

In addition, as the Igf1 gene is increased, survival of a normal T-cell is stimulated, damaged DNA is recovered, and the change of the thymocyte into cancer is suppressed. Such a mechanism actively occurs to prevent the progression of the thymocyte into the cancer and prolong a life span.

Afterward, a gene expressed by a factor of two times or more in the thymus extracted from the first group of the high-dose irradiated mice is analyzed.

Table 2 shows digitization of relative increase in genes of the high-dose irradiated mouse when a chip is scanned after the microarray test, compared to a non-irradiated group.

Specifically, it can be confirmed that Cds1 is increased by a factor of 3.6, Vegfb is increased by a factor of 3.2, Itgb3 is increased by a factor of 2.6, and S100a4 and Gzma are increased by a factor of 2.2.

In addition, expression of genes decreased by a factor of two or less in the thymuses extracted from the first group of the high-dose irradiated mice is analyzed.

Table 3 shows digitization of a relative decrease in genes of the high-dose irradiated mouse when a chip is scanned after the microarray test, compared to a non-irradiated group.

FIG. 4is a diagram of an expression mechanism of cancer progression observation index genes in a high-dose irradiated AKR/J mouse, which have an influence on the occurrence of cancer.

Referring toFIG. 4, Itga4, Itgb1, Itgav, Itga6 and Itgb4 form an integrin complex receptor on a surface of a cell membrane of the thymocyte of the high-dose irradiated AKR/J mouse to serve as an oncogene.

In addition, Raf, Myc, Fos, Trp53 and Apaf1 genes removing damaged cells by death are considerably suppressed to prevent the death of the damaged thymocyte and stimulate the occurrence of thymic carcinoma.

On the other hand, the Pi3kr1 gene stimulating cell death and the Akt2 and Mmd2 genes are activated, but Trp53 is suppressed, thereby preventing the cell death. It can be seen that as Cdc25a and Cdk2 of the genes relating to a cell cycle are repressed, the damaged DNA is not recovered and proliferation of damaged thymic carcinoma cells is stimulated, thereby stimulating progression to thymic carcinoma.

According to the present invention composed as described above, a cancer progression observation index gene specifically responding to radiation can be clearly defined by fixing the occurrence of cancer by obtaining a thymus at the time at which an AKR/J mouse in which an oncogene is inserted into the thymocyte to serve as a thymic carcinoma initiation factor, and preventing the interference of confounding variables to interpret a gene response within the thymuses having no change in weight compared to a non-irradiated mouse thymus.

Such an observation index gene serves to diagnose the occurrence of thymic carcinoma and predict progression of cancer, and thus can be used as a kit for diagnosing cancer.

The present invention relates to a cancer progression observation index gene group capable of confirming progression of cancer and a method of detecting the gene group, and a diagnosing kit capable of confirming the progression of cancer can be developed.