367
13 Vibrational Spectroscopy: Disease Diagnostics and Beyond
Phe at 1,582 cm
−1
and trp at 750 cm
−1
. the third principal component contains a
lot of biological information with mainly nucleic acid and protein contributions
but only accounts for 6.2 % of variance. there are distinctive peaks corresponding
to nucleic acids and protein vibrations. dNA and RNA contributions are observed
at 670, 720, 782, 1,092, 1,250, 1,340 and 1,583 cm
−1
. PC3 shows a strong influence of variation arising from protein vibrations, Phe (642, 1,002, 1,031, 1,583 and
1,618 cm
−1
), trp (1,208, 1,340 and 1,618 cm
−1
), tyr (642, 854 and 1,618 cm
−1
), Pro
(854 cm
−1
, 935 cm
−1
), val (935 cm
−1
), Amide I at 1,680 cm
−1
(disordered) and Amide III at 1,260 cm
−1
(disordered). the source of variations shown in the loadings is
in very good agreement with those observed in the analysis of the mean spectra for
the investigated cell lines. the main peaks in the loadings arise from protein, nucleic acid and lipid component vibrations. Each principal component is dominated
by different cellular components; water, and possibly nucleic acids and proteins in
PC1, lipids and proteins in PC2 and nucleic acids and proteins in PC3. Amide I and
Amide III contributions are present in all principal component loadings indicative
of differences in structural conformation of the protein β-sheet in PC1, α-helix in
PC2 and disordered conformation in PC3. As mentioned previously, variations in
protein, nucleic acid and lipid levels arise from the fact that the viral dNA interacts with the cellular dNA, causing reprogramming of protein expression in the
cell. It was noted that the multivariate analysis could be sustantially influenced by
water contributions in the region of 1,640 cm
−1
. Repeated over the spectral range
400–1,550 cm
−1
, the PCA gave a similar separation of the cellular types and yielded
similar principal components.
the applications of spectroscopic analysis, coupled with multivariate statistic
techniques can therefore be extended beyond diagnosis based on classification to
biochemical analysis of the underlying physiology based on changes to the molecualr composition on a cellular and subcellular level. this new technology for cervical
screening not only can distinguish cervical cells based on biochemical content but
also can elucidate the effect of hPv on the cells. As a further demonstration of the
potential of the techniques, FtIR spectroscopy was employed to further explore the
known manifestations of hPv infection in cervical cell lines [64].
differentially expressed proteins in cancer have potential utility as biomarkers.
As the cell cycle is often disrupted in a cancerous cell, proteins associated with
it are often candidate biomarkers. Putative biomarkers of cervical cancer that are
currently under study include proteins such as CdC 6 (dNA licensing protein),
minichromosome maintenance proteins (mCm 2, mCm 5), p53 or p16
INK4A
[73].
these biomarkers have been used to detect the presence of abnormal cells, based
upon immunocytochemical methods. p16
INK4A
regulates the levels of active cyclin
d/CdK in the cell, providing a feedback mechanism that regulates the levels of
mCm (minichromosome maintenance proteins), PCNA (proliferating-cell nuclear
antigen) and cyclin E. overexpression of p16
INK4A
, which is considered a marker of
elevated E7 expression, can be detected in some CIN1 lesions, as well as in CIN2
and CIN3 lesions that show evidence of integration [74, 75]. Integration of the hPv
genome into the host cell chromosome is a critical event in the development of
most cervical cancers [76]. overexpression of p16
INK4A
has been demonstrated in
13 Vibrational Spectroscopy: Disease Diagnostics and Beyond
Phe at 1,582 cm
−1
and trp at 750 cm
−1
. the third principal component contains a
lot of biological information with mainly nucleic acid and protein contributions
but only accounts for 6.2 % of variance. there are distinctive peaks corresponding
to nucleic acids and protein vibrations. dNA and RNA contributions are observed
at 670, 720, 782, 1,092, 1,250, 1,340 and 1,583 cm
−1
. PC3 shows a strong influence of variation arising from protein vibrations, Phe (642, 1,002, 1,031, 1,583 and
1,618 cm
−1
), trp (1,208, 1,340 and 1,618 cm
−1
), tyr (642, 854 and 1,618 cm
−1
), Pro
(854 cm
−1
, 935 cm
−1
), val (935 cm
−1
), Amide I at 1,680 cm
−1
(disordered) and Amide III at 1,260 cm
−1
(disordered). the source of variations shown in the loadings is
in very good agreement with those observed in the analysis of the mean spectra for
the investigated cell lines. the main peaks in the loadings arise from protein, nucleic acid and lipid component vibrations. Each principal component is dominated
by different cellular components; water, and possibly nucleic acids and proteins in
PC1, lipids and proteins in PC2 and nucleic acids and proteins in PC3. Amide I and
Amide III contributions are present in all principal component loadings indicative
of differences in structural conformation of the protein β-sheet in PC1, α-helix in
PC2 and disordered conformation in PC3. As mentioned previously, variations in
protein, nucleic acid and lipid levels arise from the fact that the viral dNA interacts with the cellular dNA, causing reprogramming of protein expression in the
cell. It was noted that the multivariate analysis could be sustantially influenced by
water contributions in the region of 1,640 cm
−1
. Repeated over the spectral range
400–1,550 cm
−1
, the PCA gave a similar separation of the cellular types and yielded
similar principal components.
the applications of spectroscopic analysis, coupled with multivariate statistic
techniques can therefore be extended beyond diagnosis based on classification to
biochemical analysis of the underlying physiology based on changes to the molecualr composition on a cellular and subcellular level. this new technology for cervical
screening not only can distinguish cervical cells based on biochemical content but
also can elucidate the effect of hPv on the cells. As a further demonstration of the
potential of the techniques, FtIR spectroscopy was employed to further explore the
known manifestations of hPv infection in cervical cell lines [64].
differentially expressed proteins in cancer have potential utility as biomarkers.
As the cell cycle is often disrupted in a cancerous cell, proteins associated with
it are often candidate biomarkers. Putative biomarkers of cervical cancer that are
currently under study include proteins such as CdC 6 (dNA licensing protein),
minichromosome maintenance proteins (mCm 2, mCm 5), p53 or p16
INK4A
[73].
these biomarkers have been used to detect the presence of abnormal cells, based
upon immunocytochemical methods. p16
INK4A
regulates the levels of active cyclin
d/CdK in the cell, providing a feedback mechanism that regulates the levels of
mCm (minichromosome maintenance proteins), PCNA (proliferating-cell nuclear
antigen) and cyclin E. overexpression of p16
INK4A
, which is considered a marker of
elevated E7 expression, can be detected in some CIN1 lesions, as well as in CIN2
and CIN3 lesions that show evidence of integration [74, 75]. Integration of the hPv
genome into the host cell chromosome is a critical event in the development of
most cervical cancers [76]. overexpression of p16
INK4A
has been demonstrated in