Abstract. Nodal status is the most significant independent prognostic factor in breast cancer. Identification of molecular markers would allow stratification of patients who require surgical assessment of lymph nodes from the large numbers of patients for whom this surgical procedure is unnecessary, thus leading to a more accurate prognosis. However, up to now, the reported studies are preliminary and controversial, and although hundreds of markers have been assessed, few of them have been used in clinical practice for treatment or prognosis in breast cancer. The purpose of the present study was to determine whether protein phosphatase Mg2+/Mn2+ dependent 1D, β-1,3-N-acetylglucosaminyltransferase, neural precursor cell expressed, developmentally down-regulated 9, prohibitin, phosphoinositide-3-kinase regulatory subunit 5 (PIK3R5), phosphatidylinositol-5-phosphate 4-kinase type IIα, TRF1-interacting ankyrin-related ADP-ribose polymerase 2, BCL2 associated agonist of cell death, G2 and S-phase expressed 1 and PAX interacting protein 1 genes, described as prognostic markers in breast cancer in a previous microarray study, are also predictors of lymph node involvement in breast carcinoma Reverse transcription-quantitative polymerase chain reaction analysis was performed on primary breast tumor tissues from women with negative lymph node involvement (n=27) compared with primary tumor tissues from women with positive lymph node involvement (n=23), and was also performed on primary tumors and paired lymph node metastases (n=11). For all genes analyzed, only the PIK3R5 gene exhibited differential expression in samples of primary tumors with positive lymph node involvement compared with primary tumors with negative lymph node involvement (P= 0.0347). These results demonstrate that the PIK3R5 gene may be considered predictive of lymph node involvement in breast carcinoma. Although the other genes evaluated in the present study have been previously characterized to be involved with the development of distant metastases, they did not have predictive potential.

The aim of this study was to find the apoptosis molecular markers involved in the cell death that might be related to photodynamic therapy (PDT) mechanisms in breast cancer. The mammary tumors were induced in 25 Sprague-Dawley female rats by a single, oral gavage of 7,12-dimethylbenz(a)anthracene (DMBA; 70 mg/kg body weight). Animals were divided into four groups: G1 (normal, without DMBA), G2 (control, without PDT treatment), G3 (euthanized 48 h after PDT), and G4 (euthanized 24 h after PDT). For PDT experiments, the photosensitizer used was Photodithazine, and 100 J/cm of light at a fluence rate of 100 mW/cm was delivered to treat lesions. A sample of each animal was investigated by quantitative real-time PCR using Rat Apoptosis RT2 Profiler™ PCR Array platform. The results showed 20 genes with differential expression between PDT and control groups. A significant upregulation was observed for pro-apoptotic genes CASP4, CASP12, CIDEA, GADD45A, and FAS and downregulation of anti-apoptotic genes MAPK8IP1, TNFRSF11B, and NAIP2 in PDT-treated tumors. These results indicate that these genes are more directly involved in cell apoptosis induced by PDT.

Breast carcinoma is a heterogeneous disease with different molecular subtypes being characterized by distinct morphological appearances, genetic alterations, and clinical presentation. This heterogeneity is the major challenge in its diagnosis and treatment. Photodynamic therapy (PDT) has been used as an alternative treatment to the conventional therapies, and it is becoming accepted as a therapeutic modality in oncology. PDT is based on the incorporation of photosensitizing molecules into tumors and, after excitation with light, induces direct tumor cell death as well as indirect effects on the tumor microenvironment. Cellular apoptosis is the main event found in all tumor tissues treated by PDT. To date, metabolic pathways influenced by PDT have not been fully elucidated, and studies involving gene expression analysis in mammary tumors after PDT are scarce. Therefore, the aim of this study was to find molecular markers involved in the apoptosis pathways that may be related to the effect of PDT in breast carcinomas. To this end, global gene expression profiles were obtained from primary breast tumors samples induced in 20 female rats Sprague-Dawley, being 10 from untreated tumor samples (group 1 or control group) and 10 breast tumors samples submitted to PDT (group 2 or treatment group). These samples were investigated by quantitative real time PCR (qRT-PCR) using the Rat Apoptosis RT2 Profiler™ PCR Array platform (Super-Array, USA) that consists of 84 genes of interest involved in the modulation of cellular apoptosis. A set of 11 genes presented different expression when comparing the groups. The HRK, BIK, CASP14, CIDEA, GADD45a, TNF, CASP1 genes showed up regulation significance at treatment group compared with the control group (Student's t-test, P<0,05). These genes play a role of induction of apoptosis among other functions. TNF-tumor necrosis factor gene, for example, plays a role in the regulation of cell proliferation, induction of apoptosis, and inflammatory response. The GADD45a may mediate a delay in G2 to M cell cycle progression, which could induce DNA repair. The BIRC5, CASP6, TNFRSF11b, TP53 genes showed down expression significance in the treatment group compared with the control (Student's t-test, P<0,05). BIRC5 gene act as an inhibitor of programmed cell death preventing or reducing the activity of caspases in any cysteine proteases groups involved in the apoptosis. These results showed that these apoptosis-associated genes could explain the rapid elimination of tumor that occurs after PDT applications in breast carcinomas, and may thus contribute to better understanding of both the breast carcinogenesis and the PDT action mechanism. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 250. doi:1538-7445.AM2012-250