XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
72
T2: O–4
Raman studies on prostate cancer cells treated with clinical doses of
ionizing radiation
Maciej Roman
1
, Agnieszka Panek
1
, Joanna Wiltowska-Zuber
1
,
and Wojciech M. Kwiatek
1
1
The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences,
Radzikowskiego 152, 31-342 Krakow, Poland, e-mail: maciej.roman@ifj.edu.pl
All living organisms are exposed to radiation all the time through natural sources like cosmic rays
and terrestrial sources such as radon, thorium or uranium. Since radiation has direct impact on tissues
and cells, it has been successfully applied for cancer treatment and diagnosis. Indeed, radiation shows
a negative effect on molecules especially on DNA, where the genetic information is stored. Thus, it is
of great importance to follow changes in DNA caused by radiation in terms of cell function,
reproducibility, and death [1, 2]. Furthermore, the influence of ionizing radiation on whole organisms
can be followed by studying processes at the cellular and molecular level. The cellular response to
radiation depends on the radiation type, LET (Linear Energy Transfer), dose, dose rate, and cell type
[2, 3]. However, the present knowledge about these processes is still incomplete and therefore there is
necessity for further detailed studies. Especially in radiobiology, it is of great importance to
understand how radiation interacts with tissues and cells. Due to existence of radioadaptive response
[4, 5] or bystander effects [6], researchers still investigate effects of low dosages for radiotherapy
reasons.
In our study, we would like to shed new light on molecular damages and repairs in cells caused by
ionizing radiation. Our research was mainly focused on changes in DNA, but also other cellular
components such as lipids and proteins. Studies were performed on PC-3 cell line, which is a human
prostate cancer line derived from bone metastasis. For the first approach the cells were irradiated with
X-rays (as reference radiation) then with protons. Due to the variable response of cells in the low and
high radiation doses we tested various doses of the X-ray irradiation to observe chemical changes in
cells. It seems vitally important to assess cellular response (including DNA damage) to X-ray
radiation in a range of relevant cell lines in order to provide systematic high-resolution information to
develop a rigorous theory of ion radiation action at the cellular and molecular level. Thus, the main
objective of this research was, therefore, to study the basic mechanisms underlying the biological
effects brought about by protons that are of relevance for the functions of cancer and healthy cells.
Furthermore, aim of the study was to investigate low dose of ionizing radiation influence on
biological systems at the cellular, sub-cellular and molecular level by means of selected non-
destructive spectroscopic methods. Due to rapid development of vibrational spectroscopy techniques
such as mapping and 3D imaging, it is an excellent chance to get new information about nature of
radiation-induced damage and its spatial distribution in cells using Raman spectroscopy with
micrometric scale resolution.
Keywords: Raman spectroscopy; ionizing radiation; prostate cancer
Acknowledgment
This work was supported by the National Science Center, Poland (Grant No. 2015/19/D/ST4/01943). The research
was partially performed using equipment purchased in the frame of the project co-funded by the Małopolska
Regional Operational Programme Measure 5.1 Krakow Metropolitan Area as an important hub of the European
Research Area for 2007–2013, project No. MRPO.05.01.00-12-013/15.
References
[1] R.L. Warters, K.G. Hofer, Radiat. Res. 69 (1977) 348.
[2] B.G. Wouters, Basic Clinical Radiobiology 27 (2009).
[3] K.M. Prise, G. Schettino, M. Folkard, K.D. Held, Lancet oncol. 6 (2005) 520.
[4] G. Olivieri, J. Bodycote, S. Wolff, Science 223, (1984) 594.
[5] K. Ishii, J. Misonoh, Physiol. Chem. Phys. Me. 28 (1996) 83.
[6] E. Pasquali, P. Giardullo, S. Leonardi, M. Tanori, V. Di Majo, S. Pazzaglia, A. Saran, Curr. Mol. Med. 12
(2012) 613.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
73
T2: O–5
Binding mechanism of the antidiabetic drug, metformin with
the digestive enzyme, pepsin: An experimental and theoretical study
Mallika Pathak
1
, Deepti Sharma
2
, Himanshu Ojha
2
, and Rita Kakkar
3
1
Department of Chemistry, Miranda House, University of Delhi, Delhi 110054, India,
e-mail: mallika.pathak@mirandahouse.ac.in
2
Division of CBRN Defence, Institute of Nuclear Medicine and Allied Sciences, Delhi 110054, India.
3
Department of Chemistry, University of Delhi, Delhi 110054, India.
Metformin is a frontline drug used to treat diabetes mellitus type-2 and is administered orally
to the patients. Pepsin is an important enzyme that primarily functions as digestive enzyme. It is
cause of concern that metformin being an orally administered drug may interact with pepsin and
consequently affect its physiological function. This may result into serious side effects like
vomiting, nausea etc. Therefore, there is a need to investigate the binding mechanism of
metformin with pepsin.
In this study, the binding of metformin with pepsin has been studied using fluorescence
spectroscopy, isothermal titration calorimetry (ITC), circular dichroism (CD) spectroscopy and
molecular modelling techniques.
Fluorescence results showed that Stern Volmer constants decreased inversely with
temperature thus quenching is essentially static in nature. The binding constant value and
stoichiometry suggested that binding forces are essentially non-covalent in nature and there is
single class of binding sites. The conformational change in pepsin upon binding was confirmed
using change in CD spectra of pepsin in different concentrations of metformin. Thermodynamic
investigations revealed that the binding of metformin to pepsin was driven essentially by
favourable enthalpy and unfavourable entropy and the major driving forces are hydrogen bond
and van der Waal forces. Molecular docking suggested that the binding of metformin to pepsin
is characterized by a high number of binding sites. Therefore, metformin binds significantly
with pepsin.
Keywords: fluorescence quenching; isothermal titration calorimetry; circular dichroisim; pepsin; metformin
Acknowledgment
We sincerely thank Dr Pratibha Jolly, Principal Investigator, D.S. Kothari Centre for Research and
Innovation, Miranda House and Head, Department of Chemistry, University of Delhi for providing support
and equipment facilities.
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