A novel knock-in prostate cancer model demonstrates biology similar to that of human prostate cancer and suitable for preclinical studies

Pivotal role of the ORAI3-STIM2 complex in the control of mitotic death and prostate cancer cell cycle progression

Prostate cancer (PCa) represents one of the most frequent diagnosed cancer in males worldwide. Due to routine screening tests and the efficiency of available treatments, PCa-related deaths have significantly decreased over the past decades. However, PCa remains a critical threat if detected at a late stage in which, cancer cells would have already detached from the primary tumor to spread and invade other parts of the body. Calcium (Ca2+) channels and their protein regulators are now considered as hallmarks of cancer and some of them have been well examined in PCa. Among these Ca2+ channels, isoform 3 of the ORAI channel family has been shown to regulate the proliferation of PCa cells via the Arachidonic Acid-mediated Ca2+ entry, requiring the involvement of STIM1 (Stromal Interaction Molecule 1). Still, no study has yet demonstrated a role of the "neglected" STIM2 isoform in PCa or if it may interact with ORAI3 to promote an oncogenic behavior. In this study, we demonstrate that ORAI3 and STIM2 are upregulated in human PCa tissues. In old KIMAP (Knock-In Mouse Prostate Adenocarcinoma) mice, ORAI3 and STIM2 mRNA levels were significantly higher than ORAI1 and STIM1. In vitro, we show that ORAI3-STIM2 interact under basal conditions in PC-3 cells. ORAI3 silencing increased Store Operated Ca2+ Entry (SOCE) and induced a significant increase of the cell population in G2/M phase of the cell cycle, consistent with the role of ORAI3 as a negative regulator of SOCE. Higher expression levels of CDK1-Y15/Cyclin B1 were detected and mitotic arrest-related death occurred after ORAI3 silencing, which resulted in activating Bax/Bcl-2-mediated apoptotic pathway and caspase-8 activation and cleavage. STIM2 and ORAI3 expression increased in M phase while STIM1 expression and SOCE amplitude significantly decreased. Taken together, ORAI3 -STIM2 complex allows a successful progression through mitosis of PCa cells by evading mitotic catastrophe.

Preclinical Models of Neuroendocrine Neoplasia

Neuroendocrine neoplasia (NENs) are a complex and heterogeneous group of cancers that can arise from neuroendocrine tissues throughout the body and differentiate them from other tumors. Their low incidence and high diversity make many of them orphan conditions characterized by a low incidence and few dedicated clinical trials. Study of the molecular and genetic nature of these diseases is limited in comparison to more common cancers and more dependent on preclinical models, including both in vitro models (such as cell lines and 3D models) and in vivo models (such as patient derived xenografts (PDXs) and genetically-engineered mouse models (GEMMs)). While preclinical models do not fully recapitulate the nature of these cancers in patients, they are useful tools in investigation of the basic biology and early-stage investigation for evaluation of treatments for these cancers. We review available preclinical models for each type of NEN and discuss their history as well as their current use and translation.

Oral administration of E-type prostanoid (EP) 1 receptor antagonist suppresses carcinogenesis and development of prostate cancer via upregulation of apoptosis in an animal model

Prostaglandin E2 plays an important role in carcinogenesis and malignant potential of prostate cancer (PC) cells by binding to its specific receptors, E-type prostanoid (EP) receptors. However, anti-carcinogenic effects of the EP receptor antagonist are unclear. In this study, we used a mouse model of PC. The mice were provided standard feed (control) or feed containing the EP1 receptor antagonist and were sacrificed at 10, 15, 30, and 52 weeks of age. Apoptosis was evaluated by immunohistochemical analysis using a cleaved caspase-3 assay. The incidence of cancer in the experimental group was significantly lower than that in the control group at 15, 30, and 52 weeks of age. The percentage of poorly differentiated PC cells was significantly lower in the experimental group than in the control group at 30 and 52 weeks of age. The percentage of apoptotic cells in the experimental group was significantly higher than that in the control group at 15, 30, and 52 weeks of age. These findings indicate that feeding with the addition of EP1 receptor antagonist delayed PC progression via the upregulation of apoptosis. We suggest that the EP1 receptor antagonist may be a novel chemopreventive agent for PC.

Biology and evolution of poorly differentiated neuroendocrine tumors

Neuroendocrine (NE) cancers are a diverse group of neoplasms typically diagnosed and treated on the basis of their site of origin. This Perspective focuses on advances in our understanding of the tumorigenesis and treatment of poorly differentiated neuroendocrine tumors. Recent evidence from sequencing indicates that, although neuroendocrine tumors can arise de novo, they can also develop as a result of lineage plasticity in response to pressure from targeted therapies. We discuss the shared genomic alterations of these tumors independently of their site of origin, and we explore potential therapeutic strategies on the basis of recent biological findings.

Vitamin D3 Prevents Calcium-Induced Progression of Early-Stage Prostate Tumors by Counteracting TRPC6 and Calcium Sensing Receptor Upregulation

Active surveillance has emerged as an alternative to immediate treatment for men with low-risk prostate cancer. Accordingly, identification of environmental factors that facilitate progression to more aggressive stages is critical for disease prevention. Although calcium-enriched diets have been speculated to increase prostate cancer risk, their impact on early-stage tumors remains unexplored. In this study, we addressed this issue with a large interventional animal study. Mouse models of fully penetrant and slowly evolving prostate tumorigenesis showed that a high calcium diet dramatically accelerated the progression of prostate intraepithelial neoplasia, by promoting cell proliferation, micro-invasion, tissue inflammation, and expression of acknowledged prostate cancer markers. Strikingly, dietary vitamin D prevented these calcium-triggered tumorigenic effects. Expression profiling and in vitro mechanistic studies showed that stimulation of PC-3 cells with extracellular Ca²⁺ resulted in an increase in cell proliferation rate, store-operated calcium entry (SOCE) amplitude, cationic channel TRPC6, and calcium sensing receptor (CaSR) expression. Notably, administration of the active vitamin D metabolite calcitriol reversed all these effects. Silencing CaSR or TRPC6 expression in calcium-stimulated PC3 cells decreased cell proliferation and SOCE. Overall, our results demonstrate the protective effects of vitamin D supplementation in blocking the progression of early-stage prostate lesions induced by a calcium-rich diet. Cancer Res; 77(2); 355-65. ©2016 AACR.

High milk consumption does not affect prostate tumor progression in two mouse models of benign and neoplastic lesions

Epidemiological studies that have investigated whether dairy (mainly milk) diets are associated with prostate cancer risk have led to controversial conclusions. In addition, no existing study clearly evaluated the effects of dairy/milk diets on prostate tumor progression, which is clinically highly relevant in view of the millions of men presenting with prostate pathologies worldwide, including benign prostate hyperplasia (BPH) or high-grade prostatic intraepithelial neoplasia (HGPIN). We report here a unique interventional animal study to address this issue. We used two mouse models of fully penetrant genetically-induced prostate tumorigenesis that were investigated at the stages of benign hyperplasia (probasin-Prl mice, Pb-Prl) or pre-cancerous PIN lesions (KIMAP mice). Mice were fed high milk diets (skim or whole) for 15 to 27 weeks of time depending on the kinetics of prostate tumor development in each model. Prostate tumor progression was assessed by tissue histopathology examination, epithelial proliferation, stromal inflammation and fibrosis, tumor invasiveness potency and expression of various tumor markers relevant for each model (c-Fes, Gprc6a, activated Stat5 and p63). Our results show that high milk consumption (either skim or whole) did not promote progression of existing prostate tumors when assessed at early stages of tumorigenesis (hyperplasia and neoplasia). For some parameters, and depending on milk type, milk regimen could even exhibit slight protective effects towards prostate tumor progression by decreasing the expression of tumor-related markers like Ki-67 and Gprc6a. In conclusion, our study suggests that regular milk consumption should not be considered detrimental for patients presenting with early-stage prostate tumors.

Models of neuroendocrine prostate cancer

Prostate cancer remains the second leading cause of cancer death in men in the USA and most western countries. Prostatic acinar adenocarcinoma is the most commonly diagnosed form of prostate cancer. Small-cell neuroendocrine carcinoma is less frequently identified at the time of initial diagnosis, but this highly aggressive form of prostate cancer is increasingly observed in patients who have failed first- and second-line hormone therapy. Thus, developing and exploring models of neuroendocrine prostate cancer (NePC) are of increasing importance. This review examines the relevant xenograft tumor and genetically engineered mouse models of NePC, with the aim of addressing salient features and clinical relevance.

TRIM59, a novel multiple cancer biomarker for immunohistochemical detection of tumorigenesis

OBJECTIVES AND DESIGN

We identified a novel TRIM59 gene, as an early signal transducer in two (SV40Tag and Ras) oncogene pathways in murine prostate cancer (CaP) models. We explore its clinical applications as a multitumour marker detecting early tumorigenesis by immunohistochemistry (IHC).

SETTING AND PARTICIPANTS

88 CaP patients were from a tissue microarray (TMA) of radical prostatectomy specimen, 42 patients from a 35 multiple tumour TMA, 75 patients with renal cell carcinoma (RCC) and 92 patients from eight different tumour groups (breast, lung, parotid, gastrointestinal, female genital tract, bladder, kidney and prostate cancer).

RESULTS

TRIM59 upregulation specifically in tumour area was determined by IHC in 291 cases of 37 tumour types. To demonstrate that TRIM59 upregulation is 'tumour-specific', we characterised a significant correlation of TRIM59 IHC signals with tumorigenesis and progression, while in control and normal area, TRIM59 IHC signal was all negative or significantly low. TRIM59 protein upregulation in prostate and kidney cancers was detectable in both intensity and extent in early tumorigenesis of prostate intraepithelial neoplasia (p<0.05) and grade 1 of RCC (p<0.05), and stopped until high grades cancer. The results of the correlation in these two large cohorts of tumour types confirmed and repeated murine CaP model studies. Enhanced TRIM59 expression was identified in most of the 37 different tumours, while the highest intensities were in lung, breast, liver, skin, tongue and mouth (squamous cell cancer) and endometrial cancers. Multiple tumour upregulation was further confirmed by comparing relative scores of TRIM59 IHC signals in eight tumours with a larger patient population; and by a mouse whole-mount embryo (14.5 days post conception) test on the origin of TRIM59 upregulation in epithelial cells.

CONCLUSIONS

TRIM59 may be used a novel multiple tumour marker for immunohistochemical detecting early tumorigenesis and could direct a novel strategy for molecular-targeted diagnosis and therapy of cancer.

Pathological significance and predictive value for biochemical recurrence of c-Fes expression in prostate cancer

BACKGROUND

c-Fes is a proto-oncogene encoded non-receptor protein-tyrosine kinase (PTK). However, genetic studies have indicated that it has anti-tumorigenic effects in certain cancers. The pathological and clinical significance of c-Fes in prostate cancer are unknown.

METHODS

Expression of c-Fes was evaluated in normal glands, prostatic intraepithelial neoplasia (PIN), cancer cells in tissues of knock-in mouse adenocarcinoma prostate (KIMAP) model, and prostate cancer patients free of metastasis. Expression of c-Fes was analyzed by immunohistochemistry, and quantified by using the immunoreactivity score (IRS) (staining intensity × percentage of positive cells). Relationships between c-Fes expression and pT stage, Gleason's score (GS), and biochemical recurrence in patients who underwent radical surgery were also investigated.

RESULTS

In KIMAP, the percentage in normal glands, PIN and cancer cells positive for c-Fes expression were 0 (0/7), 25.0 (2/8), and 100% (7/7), respectively. In human tissues, c-Fes expression was also significantly higher in cancer cells than in normal cells and PIN, and it correlated with pT stage (P < 0.001) and GS (P = 0.047). Multivariate analysis showed that c-Fes expression was an independent predictor of poor outcome poor prognosis (hazard ratio = 3.21, 95% confidence interval = 1.11-9.37, P = 0.032).

CONCLUSION

The results suggested that c-Fes expression is a useful predictor of biochemical recurrence after radical surgery. The results also suggested that c-Fes is a potentially useful therapeutic target in prostate cancer and a predictor of biochemical recurrence after radical prostatectomy.

Estrogen-initiated transformation of prostate epithelium derived from normal human prostate stem-progenitor cells

The present study sought to determine whether estrogens with testosterone support are sufficient to transform the normal human prostate epithelium and promote progression to invasive adenocarcinoma using a novel chimeric prostate model. Adult prostate stem/early progenitor cells were isolated from normal human prostates through prostasphere formation in three-dimensional culture. The stem/early progenitor cell status and clonality of prostasphere cells was confirmed by immunocytochemistry and Hoechst staining. Normal prostate progenitor cells were found to express estrogen receptor α, estrogen receptor β, and G protein-coupled receptor 30 mRNA and protein and were responsive to 1 nm estradiol-17β with increased numbers and prostasphere size, implicating them as direct estrogen targets. Recombinants of human prostate progenitor cells with rat urogenital sinus mesenchyme formed chimeric prostate tissue in vivo under the renal capsule of nude mice. Cytodifferentiation of human prostate progenitor cells in chimeric tissues was confirmed by immunohistochemistry using epithelial cell markers (p63, cytokeratin 8/18, and androgen receptor), whereas human origin and functional differentiation were confirmed by expression of human nuclear antigen and prostate-specific antigen, respectively. Once mature tissues formed, the hosts were exposed to elevated testosterone and estradiol-17β for 1-4 months, and prostate pathology was longitudinally monitored. Induction of prostate cancer in the human stem/progenitor cell-generated prostatic tissue was observed over time, progressing from normal histology to epithelial hyperplasia, prostate intraepithelial neoplasia, and prostate cancer with local renal invasion. These findings provide the first direct evidence that human prostate progenitor cells are estrogen targets and that estradiol in an androgen-supported milieu is a carcinogen for human prostate epithelium.

Characterization of the oncogenic activity of the novel TRIM59 gene in mouse cancer models

A novel TRIM family member, TRIM59 gene was characterized to be upregulated in SV40 Tag oncogene-directed transgenic and knockout mouse prostate cancer models as a signaling pathway effector. We identified two phosphorylated forms of TRIM59 (p53 and p55) and characterized them using purified TRIM59 proteins from mouse prostate cancer models at different stages with wild-type mice and NIH3T3 cells as controls. p53/p55-TRIM59 proteins possibly represent Ser/Thr and Tyr phosphorylation modifications, respectively. Quantitative measurements by ELISA showed that the p-Ser/Thr TRIM59 correlated with tumorigenesis, whereas the p-Tyr-TRIM59 protein correlated with advanced cancer of the prostate (CaP). The function of TRIM59 was elucidated using short hairpin RNA (shRNA)-mediated knockdown of the gene in human CaP cells, which caused S-phase cell-cycle arrest and cell growth retardation. A hit-and-run effect of TRIM59 shRNA knockdown was observed 24 hours posttransfection. Differential cDNA microarrray analysis was conducted, which showed that the initial and rapid knockdown occurred early in the Ras signaling pathway. To confirm the proto-oncogenic function of TRIM59 in the Ras signaling pathway, we generated a transgenic mouse model using a prostate tissue-specific gene (PSP94) to direct the upregulation of the TRIM59 gene. Restricted TRIM59 gene upregulation in the prostate revealed the full potential for inducing tumorigenesis, similar to the expression of SV40 Tag, and coincided with the upregulation of genes specific to the Ras signaling pathway and bridging genes for SV40 Tag-mediated oncogenesis. The finding of a possible novel oncogene in animal models will implicate a novel strategy for diagnosis, prognosis, and therapy for cancer.

Mouse models of prostate cancer

The development and optimization of high-throughput screening methods has identified a multitude of genetic changes associated with human disease. The use of immunodeficient and genetically engineered mouse models that mimic the human disease has been crucial in validating the importance of these genetic pathways in prostate cancer. These models provide a platform for finding novel therapies to treat human patients afflicted with prostate cancer as well as those who have debilitating bone metastases. In this paper, we focus on the historical development and phenotypic descriptions of mouse models used to study prostate cancer. We also comment on how closely each model recapitulates human prostate cancer.

Modeling prostate cancer: a perspective on transgenic mouse models

Despite considerable success in treatment of early stage localized prostate cancer (PC), acute inadequacy of late stage PC treatment and its inherent heterogeneity poses a formidable challenge. Clearly, an improved understanding of PC genesis and progression along with the development of new targeted therapies are warranted. Animal models, especially, transgenic immunocompetent mouse models, have proven to be the best ally in this respect. A series of models have been developed by modulation of expression of genes implicated in cancer-genesis and progression; mainly, modulation of expression of oncogenes, steroid hormone receptors, growth factors and their receptors, cell cycle and apoptosis regulators, and tumor suppressor genes have been used. Such models have contributed significantly to our understanding of the molecular and pathological aspects of PC initiation and progression. In particular, the transgenic mouse models based on multiple genetic alterations can more accurately address the inherent complexity of PC, not only in revealing the mechanisms of tumorigenesis and progression but also for clinically relevant evaluation of new therapies. Further, with advances in conditional knockout technologies, otherwise embryonically lethal gene changes can be incorporated leading to the development of new generation transgenics, thus adding significantly to our existing knowledge base. Different models and their relevance to PC research are discussed.

Novel steroid receptor phyto-modulator compound a inhibits growth and survival of prostate cancer cells

Androgen receptor (AR)- and glucocorticoid receptor (GR)- mediated signaling play opposite roles in prostate tumorigenesis: AR promotes prostate carcinoma (PC) development, whereas GR acts as a tumor suppressor. Compound A (CpdA) is a stable analogue of an aziridine precursor from the African shrub Salsola tuberculatiformis Botschantzev. It was shown recently that, in model cells, CpdA inhibits AR function and strongly enhances anti-inflammatory function of GR. We determined the effects of CpdA in prostate cells with different AR/GR status: (a) RWPE-1 cells (AR(low)/GR(low)), (b) PC3 and DU145 cells (GR(+)/AR(-)), (c) LNCaP cells (GR(-)/AR(+)), and (d) LNCaP-GR cells expressing both receptors. Similar to steroid hormones, CpdA induces nuclear translocation of both receptors in prostate cells. Despite this, CpdA inhibits DNA-binding and transactivation potential of AR. In addition, CpdA inhibits GR-mediated transactivation but induces GR transrepression via inhibition of several transcription factors, including nuclear factor-kappaB, AP-1, Ets-1, Elk-1, SRF, CRE/ATF, and NFATc. CpdA strongly decreases growth and induces caspase-dependent apoptosis in highly malignant PC3 and DU145 cells and in other AR/GR-expressing PC cells. The cytostatic effect of CpdA is receptor dependent: down-regulation of GR or AR expression drastically attenuates CpdA-induced PC cell growth inhibition. Finally, virtual docking analysis indicates that CpdA shares binding cavities in AR and GR ligand-binding domains with corresponding hormones and forms hydrogen bonds (H-bond) with the same amino acids that are involved in H-bond formation during steroid binding. Overall, our data suggest that CpdA is a unique dual-target steroid receptor modulator that has a high potential for PC therapy.

Functional neoangiogenesis imaging of genetically engineered mouse prostate cancer using three-dimensional power Doppler ultrasound

We report the first application of high-frequency three-dimensional power Doppler ultrasound imaging in a genetically engineered mouse (GEM) prostate cancer model. We show that the technology sensitively and specifically depicts functional neoangiogenic blood flow because little or no flow is measurable in normal prostate tissue or tumors smaller than 2-3 mm diameter, the neoangiogenesis "switch-on" size. Vascular structures depicted by power Doppler were verified using Microfil-enhanced micro-computed tomography (micro-CT) and by correlation with microvessel distributions measured by immunohistochemistry and enhanced vascularity visualized by confocal microscopy in two GEM models [transgenic adenocarcinoma of the mouse prostate (TRAMP) and PSP94 gene-directed transgenic mouse adenocarcinoma of the prostate (PSP-TGMAP)]. Four distinct phases of neoangiogenesis in cancer development were observed, specifically, (a) an early latent phase; (b) establishment of a peripheral capsular vascular structure as a neoangiogenesis initiation site; (c) a peak in tumor vascularity that occurs before aggressive tumor growth; and (d) rapid tumor growth accompanied by decreasing vascularity. Microsurgical interventions mimicking local delivery of antiangiogenesis drugs were done by ligating arteries upstream from feeder vessels branching to the prostate. Microsurgery produced an immediate reduction of tumor blood flow, and flow remained low from 1 h to 2 weeks or longer after treatment. Power Doppler, in conjunction with micro-CT, showed that the tumors recruit secondary blood supplies from nearby vessels, which likely accounts for the continued growth of the tumors after surgery. The microsurgical model represents an advanced angiogenic prostate cancer stage in GEM mice corresponding to clinically defined hormone-refractory prostate cancer. Three-dimensional power Doppler imaging is completely noninvasive and will facilitate basic and preclinical research on neoangiogenesis in live animal models.

Bub1 up-regulation and hyperphosphorylation promote malignant transformation in SV40 tag-induced transgenic mouse models

Rodents do not naturally develop prostate cancer. Currently, most widely used genetically engineered mouse prostate cancer models use SV40 T/tag oncogene. To understand the mechanism underlying prostate cancer development in transgenic and knock-in SV40 Tag mouse models, we did cDNA microarray analyses, comparing gene expression profiles of prostate cancer tissues from early-, late-, and advance-stage androgen-independent prostate cancers. Of the 67 genes that were up-regulated by > or = 10-fold, 40 are known to be required for chromosome stability. In particular, the spindle checkpoint component Bub1 was persistently up-regulated from early to advanced androgen-independent prostate cancer lesions. Significantly, Bub1, which is required for accurate chromosome segregation during mitosis, has recently been reported to bind SV40 Tag. Consistent with a spindle checkpoint defect, flow cytometry experiments indicate that advanced androgen-independent prostate cancer tumors exhibit aneuploidy, along with up-regulation of levels of both Bub1 mRNA and Bub1 protein or hyperphosphorylation. Importantly, up-regulation and hyperphosphorylation of Bub1 were also observed in established human prostate cancer cell lines and in clinical studies. Furthermore, analysis of human prostate cancer lines showed impaired spindle checkpoint function and endoreduplication following exposure to spindle toxins. Small interfering RNA-mediated repression of Bub1 in the human prostate cancer line PC-3 restrained cell proliferation, an effect mimicked by inhibition of mitogen-activated protein kinase, an upstream activator of Bub1. Thus, by perturbing Bub1 function, our observations suggest a new mechanism whereby the SV40 Tag oncoprotein promotes chromosomal instability and aneuploidy in transgenic mouse prostate cancer models. Whereas the exact details of this mechanism remain unclear, our novel findings raise the possibility of exploiting Bub1 as a new therapeutic target in the treatment of prostate cancer, the most common cancer in adult men in North America.

Markers of prostate region-specific epithelial identity define anatomical locations in the mouse prostate that are molecularly similar to human prostate cancers

Although the basic functions of the prostate gland are conserved among mammals, its morphology varies greatly among species. Comparative studies between mouse and human are important because mice are widely used to study prostate cancer, a disease that occurs in a region-restricted manner within the human prostate. An informatics-based approach was used to identify prostate-specific human genes as candidate markers of region-specific identity that might distinguish prostatic ducts prone to prostate cancer from ducts that rarely give rise to cancer. Subsequent analysis of normal and cancerous human prostates demonstrated that the genes microseminoprotein-beta (MSMB) and transglutaminase 4 (TGM4) were expressed in distinct groups of ducts in the normal human prostate, and only MSMB was detected in areas of prostate cancer. The mouse orthologs of MSMB and TGM4 were then used for expression studies in mice along with the mouse ventrally expressed gene spermine binding protein (SBP). All three genes were informative markers of region-specific epithelial identity with distinct expression patterns that collectively accounted for all ducts in the mouse prostate. Together with the human data, this suggested that MSMB expression defines an anatomical domain in the mouse prostate that is molecularly most similar to human prostate cancers. Computer-assisted serial section reconstruction was used to visualize the complete expression domains for MSMB, SBP, and TGM4 in the mouse prostate. This showed that MSMB is expressed in prostatic ducts that comprise 21% of the mouse dorso-lateral prostate. Finally, the expression of MSMB, SBP, and TGM4 was evaluated in a mouse prostate cancer model created by the prostate epithelium-specific deletion of the tumor suppressor PTEN. MSMB and TGM4 were rapidly and dramatically down-regulated in response to PTEN deletion suggesting that this model of prostate cancer includes a more rapid de-differentiation of the prostatic epithelium than is observed in organ-confined human prostate cancers.

Genomic analysis defines a cancer-specific gene expression signature for human squamous cell carcinoma and distinguishes malignant hyperproliferation from benign hyperplasia

Using high-density oligonucleotide arrays, we measured expression of >12,000 genes in surgical excisions of invasive human squamous cell carcinomas (SCCs) versus site-matched control skin. This analysis defined >1,900 genes with altered expression in SCCs that were statistically different from controls. As SCCs are composed of epithelial cells, which are both hyperplastic and invasive, we sought to define gene sets associated with these biologic processes by comparing gene expression to psoriasis vulgaris, which is a condition of benign keratinocyte hyperplasia without invasiveness or pre-malignant potential. Through this analysis, we found genes that were commonly upregulated in both conditions and unique genes with increased expression in SCCs. Differential gene regulation in these two conditions was confirmed by real-time reverse transcription-PCR and immunohistochemistry. We found that benign hyperplasia is associated with upregulation of genes including DEFB4 (defensin B4), SERPINB3 (serine proteinase inhibitor, member 3), STAT1 (signal transducer and activator of transcription 1), K16 (keratin 16), CEACAMs (carcinoembryonic antigen-related cell adhesion molecules), and WNT 5A (wingless-type MMTV integration site family, member 5A). WNT receptor frizzled homolog 6 (FZD6) and prostaglandin-metabolizing enzyme hydroxyprostaglandin dehydrogenase were increased in SCC alone. Growth factor pleiotrophin (PTN) was expressed at higher levels in non-tumor-bearing skin adjacent to excised SCC. SCC was further characterized by upregulation of matrix metalloproteinases 1, 10, and 13, cathepsin L2, cystatin E/M as well as STAT3 and microseminoprotein, beta (MSMB), and downregulation of inducible nitric oxide synthase, granzyme B, CD8, and CD83. The current study defines a unique gene expression signature for cutaneous SCC in humans and suggests potential roles for WNT, FZD, and PTN in the pathogenesis of SCC.

Establishment of a serum tumor marker for preclinical trials of mouse prostate cancer models

Current prostate cancer research in both basic and preclinical trial studies employ genetically engineered mouse models. However, unlike in human prostate cancer patients, rodents have no counterpart of prostatic-specific antigen (PSA) for monitoring prostate cancer initiation and progression. In this study, we established a mouse serum tumor marker from a mouse homologue of human prostate secretory protein of 94 amino acids (PSP94). Immunohistochemistry studies on different histologic grades from both transgenic and knock-in mouse prostate cancer models showed the down-regulation of tissue PSP94 expression (P < 0.001), the same as for PSA and PSP94 in humans. The presence of mouse serum PSP94 was shown by affinity column and immunoprecipitation purification using a polyclonal mouse PSP94 antibody. A competitive ELISA protocol was established to quantify serum PSP94 levels with a sensitivity of 1 ng/mL. Quantified serum levels of mouse PSP94 ranged from 49.84 ng/mL in wild-type mice to 113.86, 400.45, and 930.90 ng/mL in mouse prostatic intraepithelial neoplasia with microinvasion, well differentiated, moderately differentiated, and poorly differentiated prostate cancer genetically engineered prostate cancer mice, respectively (P < 0.01, n = 68). This increase in serum PSP94 is also well correlated with age and tumor weight. Through longitudinal monitoring of serum PSP94 levels of castrated mice (androgen ablation therapy), we found a correlation between responsiveness/refractory prostate tissues and serum PSP94 levels. The utility of mouse serum PSP94 as a marker in hormone therapy was further confirmed by three-dimensional ultrasound imaging. The establishment of the first rodent prostate cancer serum biomarker will greatly facilitate both basic and preclinical research on human prostate cancer.

Interferon-γ induces regression of epithelial cell carcinoma: critical roles of IRF-1 and ICSBP transcription factors

We have developed an epithelial cell carcinoma model for studying efficacy of IFNgamma gene therapy and have identified components of IFNgamma-signaling pathway responsible for its direct anti-tumor actions. The tumor results from ectopic expression of SV40 Large T-Antigen (SV40 T-Ag) oncogene in lens of transgenic mouse (alphaT3) and complete regression of the tumor is induced by targeting expression of IFNgamma into malignant lens cells. Inflammatory cells are absent in lens of alphaT3 or DT (co-expressing IFNgamma and SV40-T-Antigen) mice and the transformed lens cells are non-immunogenic, suggesting non-involvement of immunologic cells. We show that IFNgamma has direct growth-inhibitory effects on tumor cells, induces death of tumor cells by apoptosis and that these effects are mediated by two transcription factors, IRF-1 (interferon-regulatory factor-1) and ICSBP (interferon-consensus sequence-binding protein) induced by IFNgamma. Furthermore, stable transfection with ICSBP or IRF-1 construct inhibits lens carcinoma cell growth by upregulating Caspase-1, p21(WAF1) and p27 expression. In contrast, tumor progression in alphaT3 lens correlates with inhibition of IRF-1 and ICSBP expression. Our results suggest that IFNgamma gene therapy maybe effective in malignant diseases for which DNA tumor viruses are etiologic agents and that antitumor actions of IRF-1/ICSBP can be exploited therapeutically to circumvent adverse clinical effects associated with IFN therapy.

A new three-dimensional ultrasound microimaging technology for preclinical studies using a transgenic prostate cancer mouse model

Prostate cancer is the most common cancer in adult men in North America. Preclinical studies of prostate cancer employ genetically engineered mouse models, because prostate cancer does not occur naturally in rodents. Widespread application of these models has been limited because autopsy was the only reliable method to evaluate treatment efficacy in longitudinal studies. This article reports the first use of three-dimensional ultrasound microimaging for measuring tumor progression in a genetically engineered mouse model, the 94-amino acid prostate secretory protein gene-directed transgenic prostate cancer model. Qualitative comparisons of three-dimensional ultrasound images with serial histology sections of prostate tumors show the ability of ultrasound to accurately depict the size and shape of malignant masses in live mice. Ultrasound imaging identified tumors ranging from 2.4 to 14 mm maximum diameter. The correlation coefficient of tumor diameter measurements done in vivo with three-dimensional ultrasound and at autopsy was 0.998. Prospective tumor detection sensitivity and specificity were both >90% when diagnoses were based on repeated ultrasound examinations done on separate days. Representative exponential growth curves constructed via longitudinal ultrasound imaging indicated volume doubling times of 5 and 13 days for two prostate tumors. Compared with other microimaging and molecular imaging modalities, the application of three-dimensional ultrasound imaging to prostate cancer in mice showed advantages, such as high spatial resolution and contrast in soft tissue, fast and uncomplicated protocols, and portable and economical equipment that will likely enable ultrasound to become a new microimaging modality for mouse preclinical trial studies.