Mid-Infrared Imaging Is Able to Characterize and Separate Cancer Cell Lines.

Malignancies are still responsible for a large share of lethalities. Macroscopical evaluation of the surgical resection margins is uncertain. Big data based imaging approaches have emerged in the recent decade (mass spectrometry, two-photon microscopy, infrared and Raman spectroscopy). Indocianine green labelled MS is the most common approach, however, label free mid-infrared imaging is more promising for future practical application. We aimed to identify and separate different transformed (A-375, HT-29) and non-transformed (CCD986SK) cell lines by a label-free infrared spectroscopy method. Our approach applied a novel set-up for label-free mid-infrared range classification method. Transflection spectroscopy was used on aluminium coated glass slides. Both whole range spectra (4000-648 cm-1) and hypersensitive fingerprint regions (1800-648 cm-1) were tested on the imaged areas of cell lines fixed in ethanol. Non-cell spectra were possible to be excluded based on mean transmission values being above 90%. Feasibility of a mean transmission based spectra filtering method with principal component analysis and linear discriminant analysis was shown to separate cell lines representing different tissue types. Fingerprint region resulted the best separation of cell lines spectra with accuracy of 99.84% at 70-75 mean transmittance range. Our approach in vitro was able to separate unique cell lines representing different tissues of origin. Proper data handling and spectra processing are key steps to achieve the adaptation of this dye-free technique for intraoperative surgery. Further studies are urgently needed to test this novel, marker-free approach.

Cell-specific induction of c-fos expression in the pituitary gland by estrogen.

Estrogens regulate many functions of pituitary lactotrophs, including PRL gene expression, release, storage, and cellular proliferation. The mechanism by which estrogens exert such a variety of functions is poorly understood. In the uterus, estrogens rapidly and transiently induce the expression of the immediate early genes c-fos and c-jun in specific cell types. The Fos/Jun proteins form the activating protein-1 (AP1) transcription factor that mediates ligand-activated cell proliferation, differentiation, and secretion. Here we used Fischer 344 (F344) rats that develop hyperprolactinemia and prolactinomas in response to estrogens. The objectives were to: 1) determine whether estrogen induces c-fos expression in the pituitary gland and identify the responsive cells; 2) compare the dynamics of c-fos induction in the pituitary and uterus; and 3) examine the temporal relationship between c-fos expression and PRL release. Ovariectomized F344 rats were injected with 1 microg estradiol and killed at different times thereafter. Pituitaries were subjected to in situ hybridization for c-fos and immunostaining for selected pituitary cells. Estradiol stimulated c-fos expression in lactotrophs and folliculo-stellate cells within the anterior lobe without affecting either the intermediate or neural lobes. In a second experiment, c-fos messenger RNA levels were measured by solution hybridization in anterior pituitaries and uteri from estradiol-treated rats. Trunk blood was analyzed for PRL by RIA. The estrogen-induced c-fos rise in the uterus was rapid, robust, and transient, whereas that in the anterior pituitary was delayed, lower, and sustained. The profile of serum PRL levels resembles that of c-fos induction in the anterior pituitary. We conclude that: 1) both lactotrophs and folliculo-stellate cells increase c-fos expression in response to estrogens; 2) induction of c-fos expression may mediate some estrogenic effects on PRL synthesis and release and lactotroph proliferation in F344 rats; and 3) the atypical dynamics of c-fos induction in the pituitary could be due to indirect effects of estrogens on PRL-regulating factors within the hypothalamo-pituitary complex as well as to pituitary-specific estrogen receptor isoforms, coactivators, or repressors.