Pharmacological inactivation of the PI3K p110δ prevents breast tumour progression by targeting cancer cells and macrophages.

Patient selection for PI3K-targeted solid cancer treatment was based on the PIK3CA/PTEN mutational status. However, it is increasingly clear that this is not a good predictor of the response of breast cancer cells to the anti-proliferative effect of PI3K inhibitors, indicating that isoform(s) other than p110α may modulate cancer cells sensitivity to PI3K inhibition. Surprisingly, we found that although no mutations in the p110δ subunit have been detected thus far in breast cancer, the expression of p110δ becomes gradually elevated during human breast cancer progression from grade I to grade III. Moreover, pharmacological inactivation of p110δ in mice abrogated the formation of tumours and the recruitment of macrophages to tumour sites and strongly affected the survival, proliferation and apoptosis of grafted tumour cells. Pharmacological inactivation of p110δ in mice with defective macrophages or in mice with normal macrophages but grafted with p110δ-lacking tumours suppressed only partly tumour growth, indicating a requisite role of p110δ in both macrophages and cancer cells in tumour progression. Adoptive transfer of δD910A/D910A macrophages into mice with defected macrophages suppressed tumour growth, eliminated the recruitment of macrophages to tumour sites and prevented metastasis compared with mice that received WT macrophages further establishing that inactivation of p110δ in macrophage prevents tumour progression. Our work provides the first in vivo evidence for a critical role of p110δ in cancer cells and macrophages during solid tumour growth and may pave the way for the use of p110δ inhibitors in breast cancer treatment.

Topography of Protein Kinase C ßII in Benign and Malignant Melanocytic Lesions.

BACKGROUND: Protein kinase C ßII promotes melanogenesis and affects proliferation of melanocytic cells but is frequently absent or decreased in melanoma cells in vitro. OBJECTIVE: To investigate PKC-ßII expression and spatial distribution within a lesion in various benign and malignant melanocytic proliferations. METHODS: Expression of PKC-ßII was semiquantitatively assessed in the various existing compartments (intraepidermal [not nested], junctional [nested], and dermal) of benign (n = 43) and malignant (n = 28) melanocytic lesions by immunohistochemistry. RESULTS: Melanocytes in the basal layer of normal skin or in lentigo simplex stained strongly for PKC-ßII. Common nevi lacked completely PKC-ßII. All other lesions expressed variably PKC-ßII, with cutaneous melanoma metastases displaying the lowest rate of positivity (14%). In the topographical analysis within a lesion, PKC-ßII expression was largely retained in the intraepidermal and junctional part of all other lesions (dysplastic nevus, lentigo maligna, and melanoma). Reduced expression of PKC-ßII was found in the dermal component of benign and malignant lesions ( P = .041 vs intraepidermal). PKC-ßII expression in the various compartments did not differ significantly between benign and malignant lesions. CONCLUSIONS: The current study revealed a significant correlation between PKC-ßII expression and spatial localization of melanocytes, with the lowest expression found in the dermal compartment and the highest in the epidermal compartment.

Tamoxifen induces a pluripotency signature in breast cancer cells and human tumors.

Tamoxifen is the treatment of choice in estrogen receptor alpha breast cancer patients that are eligible for adjuvant endocrine therapy. However, ∼50% of ERα-positive tumors exhibit intrinsic or rapidly acquire resistance to endocrine treatment. Unfortunately, prediction of de novo resistance to endocrine therapy and/or assessment of relapse likelihood remain difficult. While several mechanisms regulating the acquisition and the maintenance of endocrine resistance have been reported, there are several aspects of this phenomenon that need to be further elucidated. Altered metabolic fate of tamoxifen within patients and emergence of tamoxifen-resistant clones, driven by evolution of the disease phenotype during treatment, appear as the most compelling hypotheses so far. In addition, tamoxifen was reported to induce pluripotency in breast cancer cell lines, in vitro. In this context, we have performed a whole transcriptome analysis of an ERα-positive (T47D) and a triple-negative breast cancer cell line (MDA-MB-231), exposed to tamoxifen for a short time frame (hours), in order to identify how early pluripotency-related effects of tamoxifen may occur. Our ultimate goal was to identify whether the transcriptional actions of tamoxifen related to induction of pluripotency are mediated through specific ER-dependent or independent mechanisms. We report that even as early as 3 hours after the exposure of breast cancer cells to tamoxifen, a subset of ERα-dependent genes associated with developmental processes and pluripotency are induced and this is accompanied by specific phenotypic changes (expression of pluripotency-related proteins). Furthermore we report an association between the increased expression of pluripotency-related genes in ERα-positive breast cancer tissues samples and disease relapse after tamoxifen therapy. Finally we describe that in a small group of ERα-positive breast cancer patients, with disease relapse after surgery and tamoxifen treatment, ALDH1A1 (a marker of pluripotency in epithelial cancers which is absent in normal breast tissue) is increased in relapsing tumors, with a concurrent modification of its intra-cellular localization. Our data could be of value in the discrimination of patients susceptible to develop tamoxifen resistance and in the selection of optimized patient-tailored therapies.

BAFF, APRIL, TWEAK, BCMA, TACI and Fn14 proteins are related to human glioma tumor grade: immunohistochemistry and public microarray data meta-analysis.

Gliomas are common and lethal tumors of the central nervous system (CNS). Genetic alterations, inflammatory and angiogenic processes have been identified throughout tumor progression; however, treatment still remains palliative for most cases. Biological research on parameters influencing cell survival, invasion and tumor heterogeneity identified several cytokines interfering in CNS inflammation, oxidative stress and malignant transformation, including TNF-superfamily (TNFSF) members. In this report we performed a meta-analysis of public gene-array data on the expression of a group of TNFSF ligands (BAFF, APRIL, TWEAK) and their receptors (BAFF-R, TACI, BCMA, Fn14) in gliomas. In addition, we investigated by immunohistochemistry (IHC) the tumor cells' expression of these ligands and receptors in a series of 56 gliomas of different grade. We show that in IHC, BAFF and APRIL as well as their cognate receptors (BCMA, TACI) and Fn14 expression correlate with tumor grade. This result was not evidenced in micro-arrays meta-analysis. Finally, we detected for the first time Fn14, BAFF, BCMA and TACI in glioma-related vascular endothelium. Our data, combined with our previous report in glioma cell lines, suggest a role for these receptors and ligands in glioma biology and advance these molecules as potential markers for the classification of these tumors to the proliferative, angiogenic or stem-like molecular subtype.

Immunohistochemical study of the angiogenetic network of VEGF, HIF1α, VEGFR-2 and endothelial nitric oxide synthase (eNOS) in human breast cancer.

BACKGROUND: The role of Nitric Oxide (NO) in angiogenesis has not been fully clarified yet. A dual role for NO, either inductive or inhibitory, has been proposed on the basis of different effects that high or low concentrations of NO may exert on the angiogenic process. Additionally, it has been referred that NO may induce VEGF production, while VEGF may induce NO production via up-regulation of the endothelial nitric oxide synthase (eNOS), the two pathways being reverse. The aim of the current study was to investigate the expression of key molecules involved in these opposite pathways in primary breast cancer. METHODS: Representative tumor samples from 242 patients with early-stage breast cancer (invasive ductal breast carcinomas) were investigated for the expression of VEGF, VEGFR-2, HIF1α, iNOS, and eNOS using immunohistochemistry. RESULTS: Endothelial NOS was found in 159 cases, VEGF in 131 cases, HIF-1α in 139 cases, VEGFR2 in 185 cases and inducible NOS (iNOS) in 22 cases. There was a significant correlation between the expression of VEGF and VEGFR-2, eNOS and VEGF, eNOS and VEGFR-2, eNOS and HIF1α. No statistically significant correlation was found between iNOS and the rest of the studied molecules. CONCLUSIONS: In breast cancer cases, the major molecules regulating NO and VEGF production can be co-expressed in the individual carcinomas implying a possibility for the relevant pathways to be active; however appropriate functional experiments remain to be conducted to prove such a hypothesis.

ERα36, a new variant of the ERα is expressed in triple negative breast carcinomas and has a specific transcriptomic signature in breast cancer cell lines.

Triple negative breast cancer is deprived of estrogen receptor alpha (ERα), progesterone receptor (PR) and HER-2 protein. It constitutes the most heterogeneous and aggressive group of breast carcinomas, for which identification of novel characteristics and characterization of putative targets becomes very demanding. In the present work we have assayed the expression of ERα36, a recently identified ERα variant of 36kDa, in a series of triple negative breast cancers, in relation to the clinical behavior and other clinico-pathological features of the tumors. While widely expressed within the cytoplasm in almost all tumors, we found that exclusively the membrane/submembrane expression of the receptor exhibits a correlation with patient's survival. Moreover, membrane ERα36 correlates in an inverse manner with the expression of miRNA210, a pro-angiogenic miR, with high prognostic relevance in triple negative carcinomas. A thorough transcriptomic, pharmacological-based approach in breast cancer cell lines, revealed an early (direct) transcriptional signature of the receptor activation, related to immune system processes and T-cell differentiation, RNA biosynthesis, regulation of metabolism, VEGF signaling and regulation of the cell cycle, with a down-regulation of CREB, NFκB and STATs transcription factors. Finally, ERα36 expression is not limited within breast cancer epithelial linen, but is equally identified in tumor vasculature, peritumoral fat tissue, lymphocytic infiltrate and stromal fibroblasts. In light of the above, ERα36 could represent a major counterpart in triple negative breast cancer.

Intravital spectral imaging as a tool for accurate measurement of vascularization in mice.

BACKGROUND: Quantitative determination of the development of new blood vessels is crucial for our understanding of the progression of several diseases, including cancer. However, in most cases a high throughput technique that is simple, accurate, user-independent and cost-effective for small animal imaging is not available. METHODS: In this work we present a simple approach based on spectral imaging to increase the contrast between vessels and surrounding tissue, enabling accurate determination of the blood vessel area. This approach is put to test with a 4T1 breast cancer murine in vivo model and validated with histological and microvessel density analysis. RESULTS: We found that one can accurately measure the vascularization area by using excitation/emission filter pairs which enhance the surrounding tissue's autofluorescence, significantly increasing the contrast between surrounding tissue and blood vessels. Additionally, we found excellent correlation between this technique and histological and microvessel density analysis. CONCLUSIONS: Making use of spectral imaging techniques we have shown that it is possible to accurately determine blood vessel volume intra-vitally. We believe that due to the low cost, accuracy, user-independence and simplicity of this technique, it will be of great value in those cases where in vivo quantitative information is necessary.