Towards Treatment Monitoring of Tumour Radiation Response with Raman Spectroscopy
Q Matthews*1,2, A Jirasek2, AG Brolo2, JJ Lum1, (1) BC Cancer Agency, Victoria, BC, Canada (2) University of Victoria, Victoria, BC, CanadaWE-C-BRA-9 Wednesday 10:30:00 AM - 12:30:00 PM Room: Ballroom A
Purpose: To use single-cell Raman spectroscopy (RS) and principal component analysis (PCA) for early treatment monitoring of radiation response.
Methods: Two human tumour cell lines, one known to be radioresistant (H460, SF2 = 0.64) and one radiosensitive (LNCaP, SF2 = 0.27), were treated with daily 2 Gy fractions of 6 MV photons, up to a maximum total dose of 10 Gy. Irradiated and unirradiated cultures were harvested and analyzed with RS each day after the previous daily fraction, and also at 2 and 3 days after the final fraction. Single-cell Raman spectra were acquired from 20 cells per sample with a Raman microscope utilizing a 785 nm excitation laser. All spectra (280 per cell line) were post-processed, and the total data set for each cell line was analyzed with PCA using standard algorithms.
Results: One radiation-induced PCA component was detected for each cell line by identification of statistically significant changes in the PCA score distributions for irradiated samples, as compared to unirradiated samples, at time points after the start of radiation treatment. The radioresistant cells (H460) exhibit a strong RS molecular radiation response signature, detectable as early as 2 days after the start of treatment, of which radiation-induced glycogen synthesis is a significant contributor. The radiosensitive cells (LNCaP) exhibit a weak molecular radiation response signature that is not correlated with the radioresistant cell response, with no contributions from glycogen. The glycogen synthesis observed in the radioresistant cells is confirmed via Western blotting to be the result of radiation-induced activation of the phosphatidylinositol-3-kinase/Akt (PI3K/Akt) signalling pathway, a molecular radiation response known to promote cell survival and confer radiation resistance.
Conclusions: This work supports the feasibility of using RS for early treatment monitoring of tumour radiation response, leading to personalized therapy.