Marco G. Cecchini

Replication-Deficient Human Adenovirus Type 35 Vectors for Gene Transfer and Vaccination: Efficient Human Cell Infection and Bypass of Preexisting Adenovirus Immunity

ABSTRACT Replication-deficient human adenovirus type 5 (Ad5) can be produced to high titers in complementing cell lines, such as PER.C6, and is widely used as a vaccine and gene therapy vector. However, preexisting immunity against Ad5 hampers consistency of gene transfer, immunological responses, and vector-mediated toxicities. We report the identification of human Ad35 as a virus with low global prevalence and the generation of an Ad35 vector plasmid system for easy insertion of heterologous genes. In addition, we have identified the minimal sequence of the Ad35-E1B region (molecular weight, 55,000 [55K]), pivotal for complementation of fully E1-lacking Ad35 vector on PER.C6 cells. After stable insertion of the 55K sequence into PER.C6 cells a cell line was obtained (PER.C6/55K) that efficiently transcomplements both Ad5 and Ad35 vectors. We further demonstrate that transduction with Ad35 is not hampered by preexisting Ad5 immunity and that Ad35 efficiently infects dendritic cells, smooth muscle cells, and synoviocytes, in contrast to Ad5.

Characterization and cloning of the E11 antigen, a marker expressed by Rat Osteoblasts and Osteocytes

A new marker for cells of the osteoblastic lineage was identified by raising monoclonal antibodies against an immortalized rat osteoblastic cell line. Among the different antibodies one was selected which, on tissue sections, strongly reacts with osteoblasts, preosteocytes, and osteocytes. This antibody, designated E11, recognizes an antigen localized at the cell surface. The cDNA encoding the E11 antigen was cloned from a cDNA library prepared from ROS 17/2.8 cells, using a eukaryotic expression system. The E11 cDNA sequence revealed homology with the murine OTS-8/gp38 sequence. In situ hybridization confirmed that E11 mRNA expression in bone is restricted to osteoblasts and osteocytes. The tissue specificity of the E11 expression was studied by immunohistochemistry and Northern blot analysis. Apart from bone, E11-positive cells were also found in lung: namely, the alveolar cells of type I. Epithelial cells of the choroid plexus and endothelial cells of lymphatic vessels were also labeled with mAb E11. These results were confirmed by Northern blot, as the 1.8 kb E11 mRNA transcript was detected in bone and also in lung, brain, and skin. In conclusion, we describe a novel osteoblastic product which is expressed by mature osteoblasts and newly formed osteocytes.

High Aldehyde Dehydrogenase Activity Identifies Tumor-Initiating and Metastasis-Initiating Cells in Human Prostate Cancer

Metastatic progression of advanced prostate cancer is a major clinical problem. Identifying the cell(s) of origin in prostate cancer and its distant metastases may permit the development of more effective treatment and preventive therapies. In this study, aldehyde dehydrogenase (ALDH) activity was used as a basis to isolate and compare subpopulations of primary human prostate cancer cells and cell lines. ALDH-high prostate cancer cells displayed strongly elevated clonogenicity and migratory behavior in vitro. More strikingly, ALDH-high cells readily formed distant metastases with strongly enhanced tumor progression at both orthotopic and metastatic sites in preclinical models. Several ALDH isoforms were expressed in human prostate cancer cells and clinical specimens of primary prostate tumors with matched bone metastases. Our findings suggest that ALDH-based viable cell sorting can be used to identify and characterize tumor-initiating and, more importantly perhaps, metastasis-initiating cells in human prostate cancer.

Optical imaging of cancer metastasis to bone marrow: a mouse model of minimal residual disease.

The development of novel anti-cancer strategies requires more sensitive and less invasive methods to detect and monitor in vivo minimal residual disease in cancer models. Bone marrow metastases are indirectly detected by radiography as osteolytic and/or osteosclerotic lesions. Marrow micrometastases elude radiographic detection and, therefore, more sensitive methods are needed for their direct identification. Injection of cancer cells into the left cardiac ventricle of mice closely mimics micrometastatic spread. When luciferase-transfected cells are used, whole-body bioluminescent reporter imaging can detect microscopic bone marrow metastases of approximately 0.5 mm(3) volume, a size below the limit in which tumors need to induce angiogenesis for further growth. This sensitivity translates into early detection of intramedullary tumor growth, preceding the appearance of a radiologically evident osteolysis by approximately 2 weeks. Bioluminescent reporter imaging also enables continuous monitoring in the same animal of growth kinetics for each metastatic site and guides end-point analyses specifically to the bones affected by metastatic growth. This model will accelerate the understanding of the molecular events in metastasis and the evaluation of novel therapies aiming at repressing initial stages of metastatic growth.

Bone morphogenetic protein 7 in the development and treatment of bone metastases from breast cancer.

Bone morphogenetic protein 7 (BMP7) counteracts the physiological epithelial-to-mesenchymal transition (EMT), a process that is indicative of epithelial plasticity. Because EMT is involved in cancer, we investigated whether BMP7 plays a role in breast cancer growth and metastasis. In this study, we show that decreased BMP7 expression in primary breast cancer is significantly associated with the formation of clinically overt bone metastases in patients with > or = 10 years of follow-up. In line with these clinical observations, BMP7 expression is inversely related to tumorigenicity and invasive behavior of human breast cancer cell lines. Moreover, BMP7 decreased the expression of vimentin, a mesenchymal marker associated with invasiveness and poor prognosis, in human MDA-MB-231 (MDA-231)-B/Luc(+) breast cancer cells under basal and transforming growth factor-beta (TGF-beta)-stimulated conditions. In addition, exogenous addition of BMP7 to TGF-beta-stimulated MDA-231 cells inhibited Smad-mediated TGF-beta signaling. Furthermore, in a well-established bone metastasis model using whole-body bioluminescent reporter imaging, stable overexpression of BMP7 in MDA-231 cells inhibited de novo formation and progression of osteolytic bone metastases and, hence, their metastatic capability. In line with these observations, daily i.v. administration of BMP7 (100 mug/kg/d) significantly inhibited orthotopic and intrabone growth of MDA-231-B/Luc(+) cells in nude mice. Our data suggest that decreased BMP7 expression during carcinogenesis in the human breast contributes to the acquisition of a bone metastatic phenotype. Because exogenous BMP7 can still counteract the breast cancer growth at the primary site and in bone, BMP7 may represent a novel therapeutic molecule for repression of local and bone metastatic growth of breast cancer.

URINARY INTERLEUKIN-8 AND 18 PREDICT THE RESPONSE OF SUPERFICIAL BLADDER CANCER TO INTRAVESICAL THERAPY WITH BACILLUS CALMETTE-GUERIN

PURPOSE We evaluate the predictive value of urinary cytokine levels of interleukin (IL) 8 and 18 for response in patients receiving intravesical bacillus Calmette-Guerin (BCG) for prevention of recurrences of superficial bladder cancer and treatment of carcinoma in situ. MATERIALS AND METHODS In 28 patients with superficial bladder cancer treated with BCG IL-8 expression in the urine during the first 6 hours after the first BCG instillation was determined. In 17 patients IL-18 levels were also evaluated during the first 12 hours after BCG instillation. IL-8 and 18 levels were determined by solid phase double ligand enzyme-linked immunosorbent assay. RESULTS In 12 of the 28 patients assessed for IL-8 expression disease recurred after a median followup of 66 months. Median IL-8 expression during the first 6 hours for these patients was 851 ng. (range 232 to 8,497). Median IL-8 expression during the first 6 hours in patients without recurrence was 4,200 ng. (range 432 to 12, 232). Of 8 patients with a followup of greater than 36 months 7 (88%) had no recurrent disease and IL-8 levels greater than 4,000 ng. Patients secreting more than 4,000 ng. IL-8 into the urine after BCG have a significantly higher chance of remaining disease-free (p <0.05), and those with elevated IL-18 expression have a significantly longer disease-free survival (p <0.05). After a median followup of 23 months (range 7 to 93) 6 of the 17 patients assessed for IL-18 expression had treatment failure. Median IL-18 expression in those patients during the first 12 hours was 2,632 pg. (range 860 to 8,298). Median IL-18 expression during the first 12 hours in patients without recurrence was 12,258 pg. (range 1,727 to 151,495). CONCLUSIONS In this study we confirmed the value of quantitative IL-8 expression in the urine during the first 6 hours after BCG instillation for superficial bladder cancer to predict freedom of disease. Furthermore, to our knowledge we report for the first time the potential value of IL-18 expression in the urine during the first 12 hours after BCG to predict freedom from disease. These findings may help improve the treatment of patients with superficial bladder cancer, especially by identifying those with a high risk of disease recurrence and progression after BCG therapy.

Interference with the Microenvironmental Support Impairs the De novo Formation of Bone Metastases In vivo

Interference with the microenvironmental growth support is an attractive therapeutic strategy for repressing metastatic tumor growth. Bone is a highly dynamic tissue that is continuously remodeled by bone resorption and subsequent bone formation. Growth factors supporting bone metastatic growth are released especially during bone resorption. Differently from most other tissues, drugs that can limit local turnover, such as bisphosphonates, are available for bone. In the present study, we tested the hypothesis that inhibition of bone turnover can affect development and growth progression of experimental bone metastasis. Whole-body bioluminescent reporter imaging was used for the detection, monitoring, and quantification in vivo of the growth progression of bone metastases induced by intracardiac or intraosseous injection of luciferase-transfected breast cancer cells (MDA-231-B/luc+) to nude mice. Suppression of bone turnover by bisphosphonates, before bone colonization by cancer cells, inhibited by a great extent the number of developing bone metastasis. Tumor growth in the few, but still developing, bone metastases was affected only transiently. Reduction of bone turnover had no effect on growth progression of bone metastases, which were already established when bisphosphonate treatment was initiated, despite a substantial reduction in osteolysis. Therefore, cancer cells metastatic to bone, after an initial growth phase that depends on the interaction with the local stroma, become independent of microenvironmental growth factor support and progress autonomously. Inhibition of bone turnover may represent a useful adjuvant therapy especially for cancer patients at risk to develop bone metastasis.

A role for N-cadherin in the development of the differentiated osteoblastic phenotype.

Cadherins are a family of cell surface adhesion molecules that play an important role in tissue differentiation. A limited repertoire of cadherins has been identified in osteoblasts, and the role of these molecules in osteoblast function remains to be elucidated. We recently cloned an osteoblast‐derived N‐cadherin gene from a rat osteoblast complementary DNA library. After in situ hybridization of rat bone and immunohistochemistry of human osteophytes, N‐cadherin expression was localized prominently in well‐differentiated (lining) osteoblasts. Northern blot hybridization in primary cultures of fetal rat calvaria and in human SaOS‐2 and rat ROS osteoblast‐like cells showed a relationship between N‐cadherin messenger RNA expression and cell‐to‐cell adhesion, morphological differentiation, and alkaline phosphatase and osteocalcin gene expression. Treatment with a synthetic peptide containing the His‐Ala‐Val (HAV) adhesion motif of N‐cadherin significantly decreased bone nodule formation in primary cultures of fetal rat calvaria and inhibited cell‐to‐cell contact in rat osteoblastic TRAB‐11 cells. HAV peptide also regulated the expression of specific genes such as alkaline phosphatase and the immediate early gene zif268 in SaOS‐2 cells. Transient transfection of SaOS‐2 cells with a dominant‐negative N‐cadherin mutant (NCADΔC) significantly inhibited their morphological differentiation. In addition, aggregation of NCTC cells derived from mouse connective tissue stably transfected with osteoblast‐derived N‐cadherin was inhibited by either treatment with HAV or transfection with NCADΔC. Together, these results strongly support a role for N‐cadherin, in concert with other previously identified osteoblast cadherins, in the late stages of osteoblast differentiation. (J Bone Miner Res 2000;15:198–208)

In vitro propagation and characterization of neoplastic stem/progenitor-like cells from human prostate cancer tissue

According to the cancer stem cell hypothesis, tumor growth is sustained by a subpopulation of cancer stem/progenitor‐like cells. Self‐renewal and high clonogenic potential are characteristics shared by normal stem and neoplastic stem/progenitor‐like cells. We investigated whether human prostate cancer specimens contain cells with these properties.

Stem‐Like Cells with Luminal Progenitor Phenotype Survive Castration in Human Prostate Cancer

Castration is the standard therapy for advanced prostate cancer (PC). Although this treatment is initially effective, tumors invariably relapse as incurable, castration‐resistant PC (CRPC). Adaptation of androgen‐dependent PC cells to an androgen‐depleted environment or selection of pre‐existing, CRPC cells have been proposed as mechanisms of CRPC development. Stem cell (SC)‐like PC cells have been implicated not only as tumor initiating/maintaining in PC but also as tumor‐reinitiating cells in CRPC. Recently, castration‐resistant cells expressing the NK3 homeobox 1 (Nkx3‐1) (CARNs), the other luminal markers cytokeratin 18 (CK18) and androgen receptor (AR), and possessing SC properties, have been found in castrated mouse prostate and proposed as the cell‐of‐origin of CRPC. However, the human counterpart of CARNs has not been identified yet. Here, we demonstrate that in the human PC xenograft BM18, pre‐existing SC‐like and neuroendocrine (NE) PC cells are selected by castration and survive as totally quiescent. SC‐like BM18 cells, displaying the SC markers aldehyde dehydrogenase 1A1 or NANOG, coexpress the luminal markers NKX3‐1, CK18, and a low level of AR (ARlow) but not basal or NE markers. These CR luminal SC‐like cells, but not NE cells, reinitiate BM18 tumor growth after androgen replacement. The ARlow seems to mediate directly both castration survival and tumor reinitiation. This study identifies for the first time in human PC SC‐/CARN‐like cells that may represent the cell‐of‐origin of tumor reinitiation as CRPC. This finding will be fundamental for refining the hierarchy among human PC cancer cells and may have important clinical implications. STEM CELLS2012;30:1076–1086