Breast Cancer Research

Con đường Akt đóng vai trò trung tâm trong việc điều chỉnh sự sống sót của tế bào, sự phát triển và trao đổi chất, và là một trong những con đường thường được kích hoạt nhất trong ung thư ở người. Tuy nhiên, vai trò của Akt trong sự phân hóa biểu mô vẫn chưa được thiết lập. Chúng tôi đã báo cáo trước đó rằng những con chuột thiếu Akt1, nhưng không phải Akt2, thể hiện một khiếm khuyết chuyển hóa rõ rệt trong thời kỳ thai kỳ muộn và cho con bú, điều này xuất phát từ việc không thể gia tăng Glut1 cũng như một số enzym tổng hợp lipid. Dù có khiếm khuyết chuyển hóa này, nhưng cả chuột thiếu Akt1 và chuột thiếu Akt2 đều thể hiện sự phân hóa biểu mô tuyến vú bình thường và sự hoạt hóa Stat5. Trên cơ sở các chức năng trùng lặp của các thành viên trong gia đình Akt, chúng tôi đã xem xét khả năng rằng Akt có thể đóng vai trò thiết yếu trong việc điều chỉnh sự phát triển của biểu mô tuyến vú mà không rõ ràng ở chuột thiếu Akt1 do được bù đắp bởi các isoform Akt khác. Để giải quyết khả năng này, chúng tôi đã lai tạo các con chuột mang biến mất có mục tiêu ở Akt1 và Akt2 và xác định tác động lên sự phân hóa vú trong thời kỳ thai kỳ và cho con bú. Việc loại bỏ một alen của Akt2 trong chuột thiếu Akt1 dẫn đến khiếm khuyết nghiêm trọng trong sự hoạt hóa Stat5 trong giai đoạn cuối của thai kỳ, kèm theo sự thất bại toàn cầu trong sự phân hóa tế bào biểu mô vú cuối cùng, được thể hiện qua sự mất hoàn toàn trong việc sản xuất ba thành phần chính của sữa: lactose, lipid và protein sữa. Khiếm khuyết này một phần là do sự thất bại của các con chuột đang mang thai Akt1 -/- ; Akt2 +/- trong việc kích thích yếu tố điều hòa tích cực của tín hiệu Prlr-Jak-Stat5, Id2, hoặc làm giảm các yếu tố điều hòa tiêu cực của tín hiệu Prlr-Jak-Stat5, caveolin-1 và Socs2. Phát hiện của chúng tôi cho thấy yêu cầu bất ngờ đối với Akt trong tín hiệu Prlr-Jak-Stat5 và xác lập Akt như một bộ điều chỉnh trung tâm thiết yếu của sự phân hóa biểu mô tuyến vú và cho con bú.

Pathologists currently diagnose breast lesions through histologic assessment, which requires fixation and tissue preparation. The diagnostic criteria used to classify breast lesions are qualitative and subjective, and inter-observer discordance has been shown to be a significant challenge in the diagnosis of selected breast lesions, particularly for borderline proliferative lesions. Thus, there is an opportunity to develop tools to rapidly visualize and quantitatively interpret breast tissue morphology for a variety of clinical applications. Toward this end, we acquired images of freshly excised breast tissue specimens from a total of 34 patients using confocal fluorescence microscopy and proflavine as a topical stain. We developed computerized algorithms to segment and quantify nuclear and ductal parameters that characterize breast architectural features. A total of 33 parameters were evaluated and used as input to develop a decision tree model to classify benign and malignant breast tissue. Benign features were classified in tissue specimens acquired from 30 patients and malignant features were classified in specimens from 22 patients. The decision tree model that achieved the highest accuracy for distinguishing between benign and malignant breast features used the following parameters: standard deviation of inter-nuclear distance and number of duct lumens. The model achieved 81 % sensitivity and 93 % specificity, corresponding to an area under the curve of 0.93 and an overall accuracy of 90 %. The model classified IDC and DCIS with 92 % and 96 % accuracy, respectively. The cross-validated model achieved 75 % sensitivity and 93 % specificity and an overall accuracy of 88 %. These results suggest that proflavine staining and confocal fluorescence microscopy combined with image analysis strategies to segment morphological features could potentially be used to quantitatively diagnose freshly obtained breast tissue at the point of care without the need for tissue preparation.

Targeted therapies for aggressive breast cancers like triple negative breast cancer (TNBC) are needed. The use of small interfering RNAs (siRNAs) to disable expression of survival genes provides a tool for killing these cancer cells. Cyclin dependent kinase 11 (CDK11) is a survival protein kinase that regulates RNA transcription, splicing and mitosis. Casein kinase 2 (CK2) is a survival protein kinase that suppresses cancer cell death. Eliminating the expression of these genes has potential therapeutic utility for breast cancer. Expression levels of CDK11 and CK2 mRNAs and associated proteins were examined in breast cancer cell lines and tissue arrays. RNA expression levels of CDC2L1, CDC2L2, CCNL1, CCNL2, CSNK2A1, CSNK2A2, and CSNK2B genes in breast cancer subtypes were analyzed. Effects following transfection of siRNAs against CDK11 and CK2 in cultured cells were examined by viability and clonal survival assays and by RNA and protein measures. Uptake of tenfibgen (TBG) nanocapsules by TNBC cells was analyzed by fluorescence-activated cell sorting. TBG nanocapsules delivered siRNAs targeting CDK11 or CK2 in mice carrying TNBC xenograft tumors. Transcript cleavage and response parameters were evaluated. We found strong CDK11 and CK2 mRNA and protein expression in most human breast cancer cells. Immunohistochemical analysis of TNBC patient tissues showed 100% of tumors stained positive for CDK11 with high nuclear intensity compared to normal tissue. The Cancer Genome Atlas analysis comparing basal to other breast cancer subtypes and to normal breast revealed statistically significant differences. Down-regulation of CDK11 and/or CK2 in breast cancer cells caused significant loss of cell viability and clonal survival, reduced relevant mRNA and protein expression, and induced cell death changes. TBG nanocapsules were taken up by TNBC cells both in culture and in xenograft tumors. Treatment with TBG- siRNA to CDK11 or TBG- siRNA to CK2αα’ nanocapsules induced appropriate cleavage of CDK11 and CK2α transcripts in TNBC tumors, and caused MDA-MB-231 tumor reduction, loss of proliferation, and decreased expression of targeted genes. CDK11 and CK2 expression are individually essential for breast cancer cell survival, including TNBC. These genes serve as promising new targets for therapeutic development in breast cancer.

Breast cancer is a major health problem, being the second deadliest form of cancer in women, behind lung cancer, and it is the leading overall cause of deaths in women between 40 and 55 years of age. Great strides have been made in the diagnosis, research, and treatment of breast cancer. However, breast cancer cells that are resistant to radiation, anti-hormonal therapy, and chemotherapy are also resistant to apoptosis. Given these facts, it is likely that innovative new strategies will be required to treat breast cancer. Lack of such strategies is a major problem, because, until they become available, it is likely that there will be little, if any reduction in the number of new breast cancer cases. The idea of activating lysosomes as a way of treating breast cancer is novel and potentially important. Lysosomal enzymes, which can degrade all biological macromolecules, induce apoptosis in a variety of model systems and in breast tumors in mammary carcinomas in animal models. In this report, we demonstrate that lysosomal enzymes can trigger apoptosis in human breast carcinoma cells as well as in rat mammary gland cells.

The response to paclitaxel varies widely in metastatic breast cancer. We analyzed data from CALGB 9342, which tested three doses of paclitaxel in women with advanced disease, to determine whether response and outcomes differed according to HER2, hormone receptor, and p53 status. Among 474 women randomly assigned to paclitaxel at a dose of 175, 210, or 250 mg/m2, adequate primary tumor tissue was available from 175. Immunohistochemistry with two antibodies and fluorescence in situ hybridization were performed to evaluate HER2 status; p53 status was determined by immunohistochemistry and sequencing. Hormone receptor status was obtained from pathology reports. Objective response rate was not associated with HER2 or p53 status. There was a trend toward a shorter median time to treatment failure among women with HER2-positive tumors (2.3 versus 4.2 months; P = 0.067). HER2 status was not related to overall survival (OS). Hormone receptor expression was not associated with differences in response but was associated with longer OS (P = 0.003). In contrast, women with p53 over-expression had significantly shorter OS than those without p53 over-expression (11.5 versus 14.4 months; P = 0.002). In addition, triple negative tumors were more frequent in African-American than in Caucasian patients, and were associated with a significant reduction in OS (8.7 versus 12.9 months; P = 0.008). None of the biomarkers was predictive of treatment response in women with metastatic breast cancer; however, survival differed according to hormone receptor and p53 status. Triple negative tumors were more frequent in African-American patients and were associated with a shorter survival.