CD24 Expression and differential resistance to chemotherapy in triple-negative breast cancer.

Breast cancer (BC) is a leading cause of cancer-related death in women. Adjuvant systemic chemotherapies are effective in reducing risks of recurrence and have contributed to reduced BC mortality. Although targeted adjuvant treatments determined by biomarkers for endocrine and HER2-directed therapies are largely successful, predicting clinical benefit from chemotherapy is more challenging. Drug resistance is a major reason for treatment failures. Efforts are ongoing to find biomarkers to select patients most likely to benefit from chemotherapy. Importantly, cell surface biomarkers CD44+/CD24- are linked to drug resistance in some reports, yet underlying mechanisms are largely unknown. This study focused on the potential role of CD24 expression in resistance to either docetaxel or doxorubicin in part by the use of triple-negative BC (TNBC) tissue microarrays. In vitro assays were also done to assess changes in CD24 expression and differential drug susceptibility after chemotherapy. Further, mouse tumor xenograft studies were done to confirm in vitro findings. Overall, the results show that patients with CD24-positive TNBC had significantly worse overall survival and disease-free survival after taxane-based treatment. Also, in vitro cell studies show that CD44+/CD24+/high cells are more resistant to docetaxel, while CD44+/CD24-/low cells are resistant to doxorubicin. Both in vitro and in vivo studies show that cells with CD24-knockdown are more sensitive to docetaxel, while CD24-overexpressing cells are more sensitive to doxorubicin. Further, mechanistic studies indicate that Bcl-2 and TGF-βR1 signaling via ATM-NDRG2 pathways regulate CD24. Hence, CD24 may be a biomarker to select chemotherapeutics and a target to overcome TNBC drug resistance

Estrogen receptor-beta is a potential target for triple negative breast cancer treatment.

Triple Negative breast cancer (TNBC) is a subtype of breast cancer that lacks the expression of estrogen receptor (ER), progesterone receptor, and human epidermal growth factor receptor 2. TNBC accounts for 15-20% of all breast cancer cases but accounts for over 50% of mortality. We propose that Estrogen receptor-beta (ERβ) and IGF2 play a significant role in the pathogenesis of TNBCs, and could be important targets for future therapy. Tissue microarrays (TMAs) from over 250 TNBC patients' were analyzed for ERβ and IGF2 expression by immunohistochemistry. Expression was correlated with clinical outcomes. In addition, TNBC cell lines Caucasians (CA): MB-231/BT549 and African Americans (AAs): MB-468/HCC70/HCC1806 were used to investigate the effect of hormonal and growth factor regulation on cell proliferation. TMAs from AAs had higher expression of ERβ and IGF2 expression when compared to CA. ERβ and IGF2 were found to be upregulated in our TNBC cell lines when compared to other cell types. TNBC cells treated with ERβ agonist displayed significant increase in cell proliferation and migration when compared to controls. AA tissue samples from TNBC patients had higher expression of ERβ. African-American breast cancer TNBC tissue samples from TNBC patients have higher expression of ERβ. In addition, TNBC cell lines were also found to express high levels of ERβ. IGF2 increased transcription of ERβ in TNBC cells. Understanding the mechanisms of IGF2/ERβ axis in TNBC tumors could provide an opportunity to target this aggressive subtype of breast cancer

HER2 testing in breast cancer: Opportunities and challenges

Human epidermal growth factor receptor 2 (HER2) is overexpressed in 15-25% of breast cancers, usually as a result of HER2 gene amplification. Positive HER2 status is considered to be an adverse prognostic factor. Recognition of the role of HER2 in breast cancer growth has led to the development of anti-HER2 directed therapy, with the humanized monoclonal antibody trastuzumab (Herceptin (R)) having been approved for the therapy of HER2-positive metastatic breast cancer. Clinical studies have further suggested that HER2 status can provide important information regarding success or failure of certain hormonal therapies or chemotherapies. As a result of these developments, there has been increasing demand to perform HER2 testing on current and archived breast cancer specimens. This article reviews the molecular background of HER2 function, activation and inhibition as well as current opinions concerning its role in chemosensitivity and interaction with estrogen receptor biology. The different tissue-based assays used to detect HER2 amplification and overexpression are discussed with respect to their advantages and disadvantages, when to test (at initial diagnosis or pre-treatment), where to test (locally or centralized) and the need for quality assurance to ensure accurate and valid testing results

Analysis of stroma-derived factors with potential prognostic and therapeutic significance in prostate cancer

Prostate cancer is the most common malignancy in Sweden with about 9000 new cases diagnosed every year. New markers are needed to improve diagnostic accuracy. The most commonly used tissue-biomarkers are basal cell markers and AMACR, often used in combination. We identified three potential tissue biomarkers, CYCS, ICK and IKBKB, by using the Human Protein Atlas database and investigated their diagnostic accuracy. The potential of these biomarkers was also compared with AMACR. Immunohistochemical analysis of the markers was performed on a tissue microarray (TMA) consisting of tissue from 40 prostate specimens, including benign prostatic tissue, atrophy, high-grade prostatic intraepithelial neoplasia (HGPIN) and prostate cancer. In addition, qRT-PCR analysis of malignant and benign frozen tissue samples from 32 radical prostatectomy specimens was performed. All four biomarkers showed a higher protein expression in prostate cancer and HGPIN than in benign tissue. The prognostic accuracy was highest for AMACR, but the results indicate that in some cases CYCS, ICK and IKBKB may serve as additional diagnostic markers. It is known that prognostic information can also be derived from tumor stroma. The prognostic value of stromal expression of PDGFRβ was therefore evaluated by immunohistochemical analysis of PDGFRβ on a TMA containing cancer and non-malignant tissue from more than 300 prostate cancer patients. The association between stromal staining intensity and a number of clinical characteristics were then analyzed. Expression of PDGFRβ in non-malignant and tumor stroma was associated with high Gleason grade and reduced cancer specific survival. Cancer associated fibroblasts (CAFs) are found in many solid tumors and promote tumor growth and progression. Identification and inhibition of molecules mediating these interactions constitute an attractive strategy for development of new cancer therapies. By comparative analyses of CAFs and normal fibroblasts from prostate tissue we have identified a number of genes upregulated in prostate CAFs. CXCL14, an orphan chemokine, was the most upregulated transcript. Overexpression of CXCL14 in fibroblasts increased their proliferation and migratory capacity. Also over-expression in fibroblasts of CAF led to increased ability of these cells to stimulate proliferation and migration of prostate cancer cells. Furthermore, fibroblasts overexpressing CXCL14 enhanced tumor growth, vascularisation and macrophage infiltration in a stroma-dependent prostate cancer model. Another transcript identified to be upregulated in prostate CAFs was GDF15, a member of the TGFβ superfamily. GDF15 was shown to stimulate fibroblast proliferation and enhanced growth, migration and invasion of prostate cancer cells. Fibroblasts over-expresssing GDF15 was also able to stimulate prostate xenograft growth when co-injected with prostate cancer cells. Interestingly, these fibroblasts also increased the ability of tumor xenograft to promote growth at a distant site suggesting direct or in-direct systemic pro-tumoral effects of fibroblast-derived GDF15. These studies thus identify a set of new diagnostic and prognostic markers for prostate cancer and stromaderived potential therapeutic targets

Cancer-Stromal Cell Interaction and Tumor Angiogenesis in Gastric Cancer

Recent studies in molecular and cellular biology have shown that tumor growth and metastasis are not determined by cancer cells alone but also by a variety of stromal cells. The stroma constitutes a large part of most solid tumors, and cancer-stromal cell interaction contributes functionally to tumor growth and metastasis. Angiogenesis is the result of an imbalance between positive and negative angiogenic factors released by tumor and host cells into the microenvironment of the neoplastic tissue. In gastric cancer, tumor cells and stromal cells produce various angiogenic factors, including vascular endothelial growth factor, interleukin-8, and platelet-derived endothelial cell growth factor. The microenvironment in the gastric mucosa may also influence the angiogenic phenotype of gastric cancer. Helicobacter pylori infection increases expression of several angiogenic factors by tumor cells. Activated fibroblasts and macrophages in tumor stroma also play an important role in angiogenesis and tumor progression. We review the current understanding of cancer-stromal cell interaction as it pertains to tumor angiogenesis in gastric cancer

TGF-β Family Signaling in Tumor Angiogenesis

Angiogenesis provides growing tumors a source of nutrients and oxygen, and a route for metastatic dissemination. In recent years anti-angiogenic therapies that primarily target the vascular endothelial growth factor (VEGF) signaling cascade have entered the clinic. However in practice, these have encountered unexpected mechanisms of resistance in many solid tumors, highlighting the need for further understanding of the basic biology behind alternative signaling pathways that drive angiogenesis. The transforming growth factor (TGF)-β superfamily of ligands and receptors are critical for vascular development and are widely implicated in cancer. Here we investigate the TGF-β signaling activity through endothelial cells (EC), including their impact on tumor angiogenesis and metastatic dissemination, through genetic modification and therapeutic inhibition.In papers I, II and IV we investigated the in vivo activing receptor-like kinase (ALK)1/bone morphogenetic protein (BMP)9 signaling axis in various mouse models of cancer. ALK1-Fc, a soluble ALK1 receptor domain ligand trap for BMP9 and BMP10, was evaluated in preclinical models of pancreatic and breast cancer, showing a decrease in angiogenesis, tumor growth and number of metastases. These reductions were enhanced when combined with chemotherapy. In the adjuvant setting, ALK1-Fc had fewer metastases in orthotopic breast cancer cell models following tumor resection. Combined deficiency of the genes encoding ALK1 and endoglin synergistically decreased the volume of pancreatic neuroendocrine tumors, whereas BMP9 knockout mice display decrease in primary tumor burden, but an increase in vessel hypersprouting and hepatic micrometastases.In papers III and IV we investigated the roles of ALK5 and TGFBR2 in pancreatic neuroendocrine tumor models with genetic modifications limited to endothelial cells (EC). Mice undergo EC-specific recombination prior to the tumor angiogenic switch for deletion of TGFBR2, ALK5, or expression of a constitutively active ALK5 mutant. EC deletion of ALK5 induced blood vessel hypersprouting in tumors and increased lymph node metastases, whereas constitutive activation of ALK5 in ECs increased hepatic metastases. TGFBR2 deletion in ECs strongly inhibits tumorigenesis, decreasing the number of tumors and tumor volume, and tumors presented with highly irregular vasculature.Our studies emphasize the impact of TGF-β signaling on tumor angiogenesis and metastatic dissemination, and this pathway presents potential targets in the development of clinical therapies. However the mechanism of action following pathway inhibition remains unclear, and further investigation is warranted