DNA analysis method and DNA analysis apparatus using terahertz wave

1. Technical Field

The present invention relates to a DNA analysis method and a DNA analyzing device using terahertz wave, and more particularly, to a DNA analysis method and a DNA analyzing device using terahertz wave capable of accurately determining a type of cancer from DNA using terahertz wave.

2. Description of the Related Art

The methylation of DNA is known to be one of the key mechanisms of cancer development. The methylation of DNA, which is a tumor marker, is a phenomenon that occurs early in cancer development and is universally found in almost all cancers and has unique characteristics depending on each organ of the human body.

FIGS. 1 A and 1 B are diagrams schematically illustrating DNA of normal cells and DNA of cancer cells. FIG. As shown in FIGS. 1 A and 1 B , the DNA of the cancer cell differs from that of normal cells in that methylation occurs when cancer develops. Therefore, carcinogenesis can be confirmed when the methylation of DNA is measured.

A quantitative method to accurately measure the degree of methylation of DNA is required in order to diagnose a carcinogenesis.

One of the quantitative measurement methods is the bisulfite conversion method and the array method shown in FIG. 2 . According to the bisulfite conversion method, uracil is generated in non-methylated DNA by a deamination reaction. The DNA treated by the bisulfite conversion method is subjected to PCR amplification and sequencing to measure the degree of methylation of DNA.

As another quantitative measurement method, there is an ELISA-like method shown in FIG. 3 . The ELISA-like method is a method for measuring the degree of methylation of DNA through the process shown in FIG. 3 .

The bisulfite conversion method, the array method and the ELISA-like method require complex pretreatment process and markers for measurement. Despite these complex pretreatment processes, the bisulfite conversion method, the array method and ELISA-like methods have relatively low accuracy. Therefore, there is a need for a new method and apparatus for accurately diagnosing type of cancer as well as diagnosis of carcinogenesis.

Patents

Patent Document 1: U.S. Patent Application Publication No. 2014/0070102

Patent Document 2: U.S. Patent Application Publication No. 2013/0130237

Patent Document 3: Canadian Patent Application Publication No. 2842458

It is an object of the present invention to provide a DNA analysis method and a DNA analyzing device using terahertz wave capable of accurately determining a type of cancer from DNA using terahertz wave.

According to one aspect of the present invention, there is provided a DNA analysis method, comprising: (a) irradiating terahertz wave onto methylated DNA; (b) detecting the terahertz wave reflected from the methylated DNA; (c) detecting a peak of a waveform of the terahertz wave detected in the step (b); and (d) determining type of cancer from the peak detected in the step (c).

It is preferable that the step (c) comprises: (c-1) fitting the waveform into a sum of a first gaussian function and a second gaussian function; and (c-2) detecting a peak of the first gaussian function and a frequency of the terahertz wave corresponding to the peak of the first gaussian function.

It is preferable that the step (d) comprises: determining the type of cancer from the frequency of the terahertz wave corresponding to the peak of the first gaussian function detected in the step (c-2).

It is preferable that the step (a) comprises: irradiating the terahertz wave onto methylated DNA while varying a frequency of the terahertz wave.

According to another aspect of the present invention, there is provided a DNA analyzing device, comprising: a terahertz wave irradiator irradiating terahertz wave onto methylated DNA; a terahertz wave detector detecting the terahertz wave reflected from the methylated DNA; a peak detector detecting a peak of a waveform of the terahertz wave detected by the terahertz wave detector; and a determination unit determining a type of cancer from the peak detected by the peak detector.

It is preferable that the peak detector comprises: a waveform fitting unit fitting the waveform into a sum of a first gaussian function and a second gaussian function; and a gaussian peak detector detecting a peak of the first gaussian function and a frequency of the terahertz wave corresponding to the peak of the first gaussian function.

It is preferable that the determination unit determining the type of cancer from the frequency of the terahertz wave corresponding to the peak of the first gaussian function detected by the gaussian peak detector.

It is preferable that the terahertz wave irradiator irradiates the terahertz wave onto methylated DNA while varying a frequency of the terahertz wave.

FIGS. 1 A and 1 B are diagrams schematically illustrating DNA of normal cells and DNA of cancer cells.

FIG. 2 illustrates a bisulfite conversion method and an array method according to the prior art.

FIG. 3 illustrates ELISA-like method according to the prior art.

FIG. 4 is a flowchart illustrating a DNA analysis method using terahertz wave according to the present invention.

FIGS. 5 A through 5 D are graphs showing waveforms of the detected terahertz wave according to the present invention.

FIG. 6 is a flowchart illustrating in detail step S 120 of FIG. 4 .

FIG. 7 is a block diagram illustrating a DNA analyzing device using terahertz wave according to the present invention.

FIG. 8 is a graph showing the absorption coefficient for an actual leukemia carcinoma in a terahertz domain in a DNA analysis method using terahertz wave according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 4 is a flowchart illustrating a DNA analysis method using terahertz wave according to the present invention. Referring to FIG. 4 , terahertz wave is irradiated onto methylated DNA (S 100 ). It is preferable to irradiate the methylated DNA with the terahertz wave while varying the frequency of the terahertz wave irradiated onto the methylated DNA. For example, the frequency of the terahertz wave may be varied from 0.4 THz to 2.5 THz while the terahertz wave is irradiated onto methylated DNA.

Thereafter, the terahertz wave reflected by the methylated DNA is detected (S 110 ). When methylated DNA is irradiated with terahertz wave, one portion of the terahertz wave is transmitted through the methylated DNA and another portion the terahertz wave is reflected. The reflected terahertz wave contains unique information about the methylated DNA. For example, the terahertz wave reflected from DNA of skin cancer cells differs from the terahertz wave reflected from the DNA of prostate cancer cells. This will be described in detail later.

Thereafter, the peak of the waveform of the terahertz wave detected in step S 110 is detected (S 120 ).

FIGS. 5 A through 5 D are graphs showing waveforms of the detected terahertz wave according to the present invention, wherein FIG. 5 A illustrates a waveform of the detected terahertz wave when the sample DNA of the normal cell is irradiated with the terahertz wave, FIG. 5 B illustrates a waveform of the detected terahertz wave when the sample DNA, which is obtained by methylating the DNA of the normal cell, is irradiated with the terahertz wave, FIG. 5 C illustrates a waveform of the detected terahertz wave when the DNA of the prostate cancer cell is irradiated with the terahertz wave, and FIG. 5 D illustrates a waveform of the detected terahertz wave when the DNA of the lung cancer cell is irradiated with the terahertz wave.

As shown in FIGS. 5 A through 5 D , the waveforms of the detected terahertz wave have a unique peak according to the type of cancer. Specifically, there is a peak at 1.68 THz for prostate cancer, and a peak at 1.66 THz for lung cancer.

FIG. 6 illustrates the method of detecting the peak in detail. Hereinafter, step S 120 will be described in more detail with reference to FIG. 6 .

FIG. 6 is a flow chart illustrating the step S 120 of FIG. 4 in detail. Referring to FIG. 6 , the waveform of the detected terahertz wave is fitted to the sum of a first gaussian function and a second gaussian function (S 121 ). Specifically, the response signal (the detected terahertz wave indicated by solid lines in FIGS. 5 A through 5 D ) obtained by irradiating the DNA with the terahertz wave while varying the frequency of the terahertz wave is curve-fitted to the first gaussian function and the second gaussian function as shown in FIGS. 5 A through 5 D . According to the findings of the inventors, this response signal is the sum of the first gaussian function (indicated by dash-dotted line) and the second gaussian function (indicated by dashed line). Therefore, the first gaussian function and the second gaussian function can be obtained from the response signal.

Thereafter, the peak of the first gaussian function and the frequency of the terahertz wave corresponding to the peak of the first gaussian function are detected (S 122 ). Here, the frequency at the peak of the response signal corresponds to the frequency of the terahertz wave at the peak of the first gaussian function. Therefore, when the frequency of the terahertz wave at the peak of the first gaussian function is obtained, the frequency at the peak of the detected terahertz wave may be obtained.

Referring back to FIG. 4 , the type of cancer is determined from the peak detected in step S 120 (S 130 ). Specifically, in step S 130 , the type of cancer is determined from the frequency of the terahertz wave corresponding to the peak of the first gaussian function detected in step S 122 . Since the frequency of the terahertz wave corresponding to the peak of the first gaussian function is unique for each type of cancer, the table of reference frequencies for different types of cancer may be stored in the memory, and the type of cancer can be determined by comparing the detected frequency and the reference frequencies to find a matching frequency.

Hereinafter, a DNA analyzing device in which the above-described DNA analysis method according to the present invention is performed will be described in detail with reference to FIG. 7 .

FIG. 7 is a block diagram illustrating the DNA analyzing device using terahertz wave according to the present invention. Referring to FIG. 7 , the DNA analyzing device according to the present invention includes a controller 100 , a terahertz wave irradiator 110 , a terahertz wave detector 120 , a peak detector 130 and a determination unit 140 .

The controller 100 controls the operation of the DNA analyzing device according to the present invention as well as the terahertz wave irradiator 110 , the terahertz wave detector 120 , the peak detector 130 and the determination unit 140 .

The terahertz wave irradiator 110 irradiates terahertz wave onto methylated DNA. Preferably, the terahertz wave irradiator 110 irradiates the terahertz wave onto the methylated DNA while varying the frequency of the irradiated terahertz wave. That is, the terahertz wave irradiator 110 performs step S 100 of FIG. 4 .

The terahertz wave detector 120 detects a portion of the terahertz wave reflected by the methylated DNA. That is, the terahertz wave detector 120 performs step S 110 of FIG. 4 .

The peak detector 130 detects the peak of the waveform of the terahertz wave detected by the terahertz wave detector 120 . That is, the peak detector 130 performs step S 120 of FIG. 4 .

The peak detector 130 may include a waveform fitting unit 131 and a gaussian peak detector 132 .

The waveform fitting unit 131 fits the waveform to the sum of the first gaussian function and the second gaussian function. That is, the waveform fitting unit 131 performs step S 121 of FIG. 6 .

The gaussian peak detector 132 detects the peak of the first gaussian function and the frequency of the terahertz wave corresponding to the peak of the first gaussian function. That is, the gaussian peak detector 132 performs step S 122 of FIG. 6 .

The determination unit 140 determines the type of cancer from the peak detected by the peak detector 130 . That is, the determination unit 140 performs step S 130 of FIG. 4 . Specifically, the determination unit 140 determines the type of cancer from the frequency of the terahertz wave corresponding to the peak of the first gaussian function detected by the gaussian peak detector 132 .

FIG. 8 is a graph showing the absorption coefficient for leukemic carcinoma in the terahertz domain in the DNA analysis method using the terahertz wave according to the present invention. FIG. 8 illustrates the terahertz absorption coefficient α of the DNA samples extracted from different leukemia carcinomas.

In FIG. 8 , “Raji” refers to Burkitt's lymphoma, “HL-60” refers to acute promyelocytic leukemia, “SU-DHL-1” refers to Anaplastic Large Cell Lymphoblastic Leukemia (ALCL), and CCRF-CEM refers to acute lymphoblastic leukemia.

As shown in FIG. 8 , the terahertz absorption coefficients α of the DNA samples have different peaks depending on the leukemia carcinomas. Therefore, the type of cancer may be accurately determined by using the DNA analysis method using the terahertz wave according to the present invention.

The DNA analysis method and DNA analyzing device of the present invention has industrial applicability since the type of cancer may be accurately determined from DNA using terahertz wave.