Differentiation of col i and Col III isoforms in stromal models of ovarian cancer by analysis of second harmonic generation polarization and emission directionality

Karissa Tilbury, Chi Hsiang Lien, Shean-Jen Chen, Paul J. Campagnola*

*Corresponding author for this work

Research output: Contribution to journalArticle

36 Scopus citations

Abstract

A profound remodeling of the extracellular matrix occurs in many epithelial cancers. In ovarian cancer, the minor collagen isoform of Col III becomes upregulated in invasive disease. Here we use second harmonic generation (SHG) imaging microscopy to probe structural differences in fibrillar models of the ovarian stroma comprised of mixtures of Col I and III. The SHG intensity and forward-backward ratios decrease with increasing Col III content, consistent with decreased phasematching due to more randomized structures. We further probe the net collagen α-helix pitch angle within the gel mixtures using what is believed to be a new pixel-based polarization-resolved approach that combines and extends previous analyses. The extracted pitch angles are consistent with those of peptide models and the method has sufficient sensitivity to differentiate Col I from the Col I/Col III mixtures. We further developed the pixel-based approach to extract the SHG signal polarization anisotropy from the same polarization-resolved image matrix. Using this approach, we found that increased Col III results in decreased alignment of the dipole moments within the focal volume. Collectively, the SHG measurements and analysis all indicate that incorporation of Col III results in decreased organization across several levels of collagen organization. Furthermore, the findings suggest that the collagen isoforms comingle within the same fibrils, in good agreement with ultrastructural data. The pixel-based polarization analyses (both excitation and emission) afford determination of structural properties without the previous requirement of having well-aligned fibers, and the approaches should be generally applicable in tissue.

Original languageEnglish
Pages (from-to)354-365
Number of pages12
JournalBiophysical Journal
Volume106
Issue number2
DOIs
StatePublished - 21 Jan 2014

Fingerprint Dive into the research topics of 'Differentiation of col i and Col III isoforms in stromal models of ovarian cancer by analysis of second harmonic generation polarization and emission directionality'. Together they form a unique fingerprint.

Cite this