Raman Spectroscopic Study of Radioresistant Oral Cancer Sublines Established by Fractionated Ionizing Radiation

Abstract

Radiotherapy is an important treatment modality for oral cancer. However, development of radioresistance is a major hurdle in the efficacy of radiotherapy in oral cancer patients. Identifying predictors of radioresistance is a challenging task and has met with little success. The aim of the present study was to explore the differential spectral profiles of the established radioresistant sublines and parental oral cancer cell lines by Raman spectroscopy. We have established radioresistant sublines namely, 50Gy-UPCI:SCC029B and 70Gy-UPCI:SCC029B from its parental UPCI:SCC029B cell line, by using clinically admissible 2Gy fractionated ionizing radiation (FIR). The developed radioresistant character was validated by clonogenic cell survival assay and known radioresistance-related protein markers like Mcl-1, Bcl-2, Cox-2 and Survivin. Altered cellular morphology with significant increase (p<0.001) in the number of filopodia in radioresistant cells with respect to parental cells was observed. The Raman spectra of parental UPCI:SCC029B, 50Gy-UPCI:SCC029B and 70Gy-UPCI:SCC029B cells were acquired and spectral features indicate possible differences in biomolecules like proteins, lipids and nucleic acids. Principal component analysis (PCA) provided three clusters corresponding to radioresistant 50Gy, 70Gy-UPCI:SCC029B sublines and parental UPCI:SCC029B cell line with minor overlap, which suggest altered molecular profile acquired by the radioresistant cells due to multiple doses of irradiation. The findings of this study support the potential of Raman spectroscopy in prediction of radioresistance and possibly contribute to better prognosis of oral cancer.

Raman Micro-Spectroscopy for Rapid Screening of Oral Squamous Cell Carcinoma

“…For example, the peak at ~720cm -1 can be associated with lipidic components, which are relatively strong in the cytoplasm, while the peak at ~790cm -1 is associated with nucleic acids, predictably relatively strong in the nucleus and nucleolus. The changes in the spectral region from 1200 to 1400 cm -1 are more complex and subtle, illustrating the need for more sophisticated multivariate data analysis techniques such as PCA (Yasser et al, 2014;Bonnier and Byrne, 2012).…”

“…The changes in the spectral region from 1200 to 1400 cm-1 are more complex and subtle, illustrating the need for more sophisticated multivariate data analysis techniques such as PCA (Yasser et al, 2014;Bonnier and Byrne, 2012).…”

Raman difference spectroscopy: a non-invasive method for identification of oral squamous cell carcinoma

“…First in vivo studies showed that the discrimination between healthy, malignant and premalignant oral tissue lesions is achievable and even early dysplastic stages of oral malignancy may be differentiated sufficiently due to its high sensitivity regarding molecular changes in the tissue [41][42][43]. According to these preliminary in vivo findings, recent works on oral spectral cytopathology showed that malignant cells can be differentiated significantly from physiological oral cells, even if morphological criteria do not indicate cancerous alterations [24], whereas studies on oral cell lines evaluate the role of radio-therapeutic resistance by investigating their spectroscopic patterns [44]. The spectral changes are mainly assignable to the change of the concentration of nucleic acids relative to the concentration of proteins and will be discussed in more detail later [42,43,45,46].…”

Applications of Raman spectroscopy in dentistry part II: Soft tissue analysis

“…SERS improves the Raman signal by 10 9 -10 14 times (45). In addition, the robust fluorescence background is greatly reduced, due to the absorption of molecules on the metal nanoparticles, there by resonance enhancement of particular molecular vibrations can be achieved (5).…”

“…In particular, the molecular fingerprint in the range of 1800 to 100cm 1 which coincide with the spectra of biochemical structures provides the data of specific biochemical structures (biochemical signatures) of the tissue, providing an opportunity to distinguish between tissue types. Additionally, spectral collection can be performed in vitro or in vivo without disturbing the cellular environment, and it has the capacity of detecting minimal alterations in the biochemical composition of living cells to produce a diagnostic molecular fingerprint of the target tissue without provoking photo-induced cellular damage (45,51).…”