RESUMO
Background: Breast cancer developed at a young age (≤45 years) is hypothesized to have unique biology; however, findings in this field are controversial. Methods: We compared the whole transcriptomic profile of young vs. old-age breast cancer using DNA microarray. RNA was extracted from 13 fresh estrogen receptor (ER)-positive primary breast cancer tissues of untreated patients (7 = young age ≤45 years and 6 = old age ≥55 years). In silico validation for the differentially expressed genes (DEGs) by young-age patients was conducted using The Cancer Genome Atlas (TCGA) database. Next, we analyzed the protein expression encoded by two of the significantly down-regulated genes by young-age patients, Glycine N-acyltransferase-like 1 (GLYATL-1) and Ran-binding protein 3 like (RANBP3L), using immunohistochemical analysis in an independent cohort of 56 and 74 ER-positive pre-therapeutic primary breast cancer tissues, respectively. Results: 12 genes were significantly differentially expressed by young-age breast cancers (fold change >2 or <2- with FDR p-value < 0.05). TCGA data confirmed the differential expression of six genes. Protein expression analysis of GLYATL-1 and RANBP3L did not show heterogeneous expression between young and old-age breast cancer tissues. Loss of expression of GLYATL-1 was significantly (p-value 0.005) associated with positive lymph node status. Higher expression of RANBP3L was significantly associated with breast cancers with lower histopathological grades (p-value 0.038). Conclusions: At the transcriptomic level, breast cancer developed in young and old age patients seems homogenous. The variation in the transcriptomic profiles can be attributed to the other clinicopathological characteristics rather than the age of the patient.
RESUMO
BACKGROUND: To elucidate the role of rapamycin and PF4 on apoptosis regulation via Bax (pro-apoptosis), Bcl-2 (anti-apoptosis) and survivin activation on the growth in the 1-methyl-1-nitrosourea -induced invasive breast carcinoma model. MATERIALS AND METHODS: Thirty five female Sprague Dawley rats at age 21-day old were divided into 4 groups; Group 1 (control, n=10), Group 2 (PF4, n=5), Group 3 (rapamycin, n=10) and Group 4 (rapamycin+PF4, n=10). MNU was administered intraperitionally, dosed at 70 mg/kg body weight. The rats were treated when the tumors reached the size of 14.5 ± 0.5 mm and subsequently sacrificed after 5 days. Rapamycin and PF4 were administered as focal intralesional injections at the dose of 20 µg/lesion. The tumor tissue was then subjected to histopathological examinations for morphological appraisal and immunohistochemical assessment of the pro-apoptotic marker, Bax and anti-apoptotic markers, Bcl-2 and survivin. RESULTS: The histopathological pattern of the untreated control cohort showed that the severity of the malignancy augments with mammary tumor growth. Tumors developing in untreated groups were more aggressive whilst those in treated groups demonstrated a transformation to a less aggressive subtype. Combined treatment resulted in a significant reduction of tumor size without phenotypic changes. Bax, the pro-apoptotic marker, was significantly expressed at higher levels in the rapamycin-treated and rapamycin+PF4-treated groups compared to controls (p<0.05). Consequently, survivin was also significantly downregulated in the rapamycin-treated and rapamycin+PF4-treated group and this was significantly different when compared to controls (p). CONCLUSIONS: In our rat model, it could be clearly shown that rapamycin specifically affects Bax and survivin signaling pathways in activation of apoptosis. We conclude that rapamycin plays a critical role in the induction of apoptosis in MNU-induced mammary carcinoma.
