Label-Free Characterization of Cancer-Activated Fibroblasts Using Infrared Spectroscopic Imaging

Abstract

Glandular tumors arising in epithelial cells comprise the majority of solid human cancers. Glands are supported by stroma, which is activated in the proximity of a tumor. Activated stroma is often characterized by the molecular expression of α-smooth muscle actin (α-SMA) within fibroblasts. However, the precise spatial and temporal evolution of chemical changes in fibroblasts upon epithelial tumor signaling is poorly understood. Here we report a label-free method to characterize fibroblast changes by using Fourier transform infrared spectroscopic imaging and comparing spectra with α-SMA expression in primary normal human fibroblasts. We recorded the fibroblast activation process by spectroscopic imaging using increasingly tissue-like conditions: 1), stimulation with the growth factor TGFβ1; 2), coculture with MCF-7 human breast cancerous epithelial cells in Transwell coculture; and 3), coculture with MCF-7 in three-dimensional cell culture. Finally, we compared the spectral signatures of stromal transformation with normal and malignant human breast tissue biopsies. The results indicate that this approach reveals temporally complex spectral changes and thus provides a richer assessment than simple molecular imaging based on α-SMA expression. Some changes are conserved across culture conditions and in human tissue, providing a label-free method to monitor stromal transformations.

Diagnosis of Periodontal Disease from Saliva Samples Using Fourier Transform Infrared Microscopy Coupled with Partial Least Squares Discriminant Analysis

“…The IR spectrum of a biological sample is formed by superposition of all infrared-active vibrational modes of all the molecules present in the sample. Therefore, FT-IR has been recently applied to analyze biological samples for the following purposes: classification of bacteria, 4-11 discrimination of cancer cells, [12][13][14][15][16][17][18][19][20] detection of scrapie, 18,[21][22][23] and histopathologic recognition. 24,25 Importantly, Xiang et al used mid-infrared spectroscopy to analyze the gingival crevicular fluid (GCF) in order to determine differences between periodontitis, gingivitis, and normal sites.…”

Attenuated total reflectance Fourier-transform infrared spectroscopic imaging for breast histopathology

“…MCF-7 cells were grown according to ATCC specifications as previously described [27]. At passage number 16, a 70% confluent T-75 flask of MCF-7 cells was treated with 0.5 μg/μl colcemid (Karyomax Colcemid solution, Invitrogen, Carlsbad CA) for 10 hours to arrest the cells during metaphase.…”

Infrared spectroscopic imaging: Label-free biochemical analysis of stroma and tissue fibrosis

“…These relationships arise from the fact that stromal or abnormal fibrotic regions are often the surrounding environment in which pathologic processes of the epithelium take place. For example, FT-IR investigations of co-culture of fibroblasts with breast cancer cell lines highlight the interaction between the former and the latter (Holton, S. et al, 2011; Holton et al, 2014; Holton, S.E. et al, 2011).…”