Laboratory Study for Analysis of Intra-tumor Heterogeneity of Ovarian Cancer by Fourier Transform Infrared Spectroscopy

  Objective  Our study aimed to establish a potential way of fourier transform infrared(FTIR) spectra to diagnose malignant tumors.

  Methods  Ovarian cancer cell subclones with high(A-H) or low(A-L) malignant potential were confirmed by Matrigel invasive/migratory assay in vitro and the tumor xenograft model in vivo. FTIR spectra of cells was recorded and analyzed in the region from 600 cm^-1 to 4000 cm^-1.

  Results  A-Hcells were confirmed to have higher invasive and migratory activities in vitro compared with A-L cells(2.211±0.256 vs. 0.149±0.097, P=0.0003; 2.412±0.298 vs. 0.337±0.079, P=0.0005).A-H-derived tumors were significantly larger than A-L-derived tumors(2.42 cm±0.43 cm vs. 0.63 cm±0.22 cm, P < 0.0001). Significant spectral differences between A-H and A-L cells were observed in the band intensity of 1086 cm^-1 and 1240 cm^-1(0.359±0.014 vs. 0.323±0.018, P=0.020; 0.343±0.010 vs. 0.317±0.012, P=0.021), as well as in that of 1655 cm^-1(1.710±0.024 vs. 1.640±0.017, P=0.045), 2925 cm^-1(0.669±0.025 vs.0.613±0.016, P=0.034) and 2853 cm^-1(0.397±0.008 vs. 0.376±0.010, P=0.039), which indicated higher amounts and synthesis of nucleic acids, proteins and lipids in A-H cells. The amount of secondary protein structures of β-sheet and turns in A-H was higher than that in A-L(22.50±0.54 vs. 21.30±0.50, P=0.037; 50.00±1.12 vs. 47.70±0.76, P=0.029). The amount of random coil component of protein in A-H was lower than that in A-L(8.50±0.82 vs. 11.50±1.32, P=0.011).

  Conclusions  FTIR quickly provides important and reliable information about heterogeneous ovarian cancerous cells on the difference in molecular components and structures. The findings of this study demonstrate the potential use of infrared spectroscopy in differentiating ovarian tumors at different developing stages.