Abstract 1883: Highly effective screening of breast cancer risk factors by compound Raman analysis of 3D culture of human mammary epithelium

The factors responsible for the transition from a normally differentiated breast epithelium to a neoplastic lesion remain largely undeciphered. Loss of apical polarity is one of the earliest changes observed in tissue architecture in breast neoplasia. However, the microenvironmental factors that control apical polarity are not known. We propose that screening for factors that control apical polarity might provide key answers regarding mechanisms that are involved in very early alterations necessary to permit breast cancer development. In this work, we applied compound Raman microscopy, which combines coherent anti-Stokes Raman scattering (CARS) imaging and confocal Raman microspectroscopy, to simultaneously mapping lipid distribution and analyzing lipid phases of live human mammary epithelium in a high throughput (HTP) 3D culture model that recapitulates polarized mammary acini. Owing to EGTA (ethylene glycol tetraacetic acid) treatment, which significantly induces the loss of apical polarity, we analyzed a total of 40 polarized and 40 nonpolarized mammary acini. The degree of lipid ordering, represented by the ratio between the areas under Raman bands at 2885 cm-1 (A2885) and 2850 cm-1 (A2850), A2885/A2850 (R), was found significantly higher in apical membrane (ApM) relative to basal membrane (BaM) for polarized mammary acini, but significantly lower for nonpolarized mammary acini by using student9s t-test. According to this result, a ratio ApM_R / BaM_R was defined to represent the relative degree of lipid ordering of ApM compared with BaM. We then found that ApM_R / BaM_R successfully distinguished polarized and nonpolarized mammary acini at a cut-off of 1 with high sensitivity and specificity. We, for the first time, provide direct evidence of polarized sorting of lipids in live human mammary epithelium. Most importantly, the same mammary acinus undergoing treatment could be monitored over a period of time, which revealed the dynamic changes of apical polarity without fixation and staining. Thus, compound Raman microscopy could eliminate the uncertainty caused by acinus-to-acinus variability and become an effective and accurate screening method of breast cancer risk factors that act on tissue polarity. Among the studies that prevail, there is enough evidence to support a role of nutrition and diet in breast cancer incidence. Our screening platform should assist in identifying certain types of fatty acids (FAs) and other dietary factors that initiate the very early stage of breast neoplasia as well as compounds that might help maintain breast tissue integrity and thus protect against breast neoplasia. The ultimate list of risk and protective nutritional factors could promote precise mechanistic studies on how these factors affect apical polarity, and set up a solid basis for the design of better prevention and therapeutic strategies to reduce breast cancer incidence. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1883.