Label-free FTIR spectroscopy detects and visualizes the early stage of pulmonary micrometastasis seeded from breast carcinoma

Abstract

An application of FTIR spectroscopic imaging for the identification and visualization of early micrometastasis from breast cancer to lungs in a murine model is shown. Spectroscopic and histological examination is focused on lung cross-sections derived from animals at the early phase of metastasis (early micrometastasis, EM) as compared to healthy control (HC) and late phase of metastasis (advanced macrometastasis, AM) using murine model of metastatic breast cancer with 4T1 cells orthotopically inoculated. FTIR imaging allows for a detailed, objective and label-free differentiation and visualization of EM foci including large and small micrometastases as well as single cancer cells grouped in clusters. An effect of the EM phase on the entire lung tissue matrix as well as characteristic biochemical profiles for HC and advanced macrometastasis were determined from morphological and spectroscopic points of view. The extraordinary sensitivity of FTIR imaging toward EM detection and discrimination of AM borders confirms its applicability as a complementary tool for the histopathological assessment of the metastatic cancer progression.

Fourier transform infrared spectroscopic signature of blood plasma in the progression of breast cancer with simultaneous metastasis to lungs

“…As seen in Figure , the greatest variance is found for IR spectra from the micrometastatic (week 3) and macrometastatic phases (week 4), particularly in the 3600‐2800 cm −1 region. This observation could be congruent with the largest variability of a number of metastatic foci present in lungs on weeks 3 and 4 as discussed in our reports . Indeed, it indicates that plasma IR spectra reflect variation in the rate of tumor growth among animals.…”

High and ultra‐high definition of infrared spectral histopathology gives an insight into chemical environment of lung metastases in breast cancer

“…1280 and 1200 cm −1 indicate remodelling of basement membranes due to the attack of cancer cells. Similarly to the amide I band at 1653 cm −1 , the ratio of bands assigned to cholesterol esters/phospholipids and glycosylated proteins (1169/1153 cm −1 ) indicates a spectral feature of inflamed cells (gray trace) that is a decreased content of carbohydrates compared to red and green classes. Moreover, bands at 1072, 1060 and 1037 cm −1 (attributed to DNA, phospholipids and glycogen, respectively ) highlight structural reorganisation of genetic material and lipidic/carbohydrate metabolism during the metastasic process and its distinct nature from surrounding inflamed matrix.…”

“…We have previously reported FTIR characterization of cancer cell clusters attached to the vein wall which penetrate further blood vessels and form metastatic foci in lung parenchyma around the vessel . Such metastatic expansion is very typical for the orthotropic breast carcinoma mouse model where the viable mouse mammary adenocarcinoma (4 T1) cells spontaneously metastasize to lungs via blood vessels.…”

“…In this work, we focused on high definition (HD) and ultra‐high definition (UHD) FTIR spectroscopic imaging of metastatic foci from a murine model of pulmonary metastasis in a 4 T1 carcinoma model of breast cancer, described in detail elsewhere . For this purpose, we used a new optic configuration introduced by Agilent Technologies in its IR microscope which provides additional 5× enhanced magnification.…”

“…The staining with hematoxylin and eosin (H&E) of lung cross sections indicates that morphology of lung tissue in the third and fourth week after cancer cells transplantation is already characterized by clear‐cut metastatic sites in lung parenchyma and pleural cavity surrounded by the lung tissue exhibiting features of local inflammation and healthy tissues in some sites. At this stage, metastasis is mainly defined as macrometastasis—a group of more than 10 cancer cells . On the week five after cancer cells transplantation, the advanced metastatic phase is recognized by extensive metastatic sites as well as progressive leucocytosis and systemic inflammation .…”