A novel signaling axis of matriptase/PDGF-D/ß-PDGFR in human prostate cancer.

Increasing evidence indicates the significance of platelet-derived growth factor receptor-ß (ß-PDGFR) signaling in prostate cancer (PCa). Accordingly, preclinical studies suggest the potential of ß-PDGFR as a therapeutic target in metastatic PCa. However, a ligand responsible for ß-PDGFR activation in PCa was unknown, and recent clinical trials with imatinib mesylate showed limited success due to normal tissue toxicity. Similarly, in spite of mounting evidence indicating the significance of matriptase in PCa, little is known about its substrates or molecular actions during PCa progression. Here, we identified PDGF-D as a ligand for ß-PDGFR in PCa and discovered matriptase as its regulator. Matriptase activates PDGF-D by proteolytic removal of the CUB domain in a 2-step process, creating a hemidimer, followed by growth factor domain dimer (GFD-D) generation. Matriptase can deactivate PDGF-D by further proteolytic cleavage within the GFD, revealing its biphasic regulation. Importantly, PDGF-D/matriptase colocalization is accompanied with ß-PDGFR phosphorylation in human PCa tissues. This study unveiled a novel signaling axis of matriptase/PDGF-D/ß-PDGFR in PCa, providing new insights into functional interplay between serine protease and growth factor signaling networks.

MDM2 and Ki-67 predict for distant metastasis and mortality in men treated with radiotherapy and androgen deprivation for prostate cancer: RTOG 92-02.

PURPOSE MDM2 regulates p53, which controls cell cycle arrest and apoptosis. Both proteins, along with Ki-67, which is an established strong determinant of metastasis, have shown promise in predicting the outcome of men treated with radiation therapy (RT) with or without short-term androgen deprivation (STAD). This report compares the utility of abnormal expression of these biomarkers in estimating progression in a cohort of men treated on RTOG 92-02. PATIENTS AND METHODS Adequate tissue for immunohistochemistry was available for p53, Ki-67, and MDM2 analyses in 478 patient cases. The percentage of tumor nuclei staining positive (PSP) was quantified manually or by image analysis, and the per-sample mean intensity score (MIS) was quantified by image analysis. Cox regression models were used to estimate overall mortality (OM), and Fine and Gray's regressions were applied to the end points of distant metastasis (DM) and cause-specific mortality (CSM). Results In multivariate analyses that adjusted for all markers and treatment covariates, MDM2 overexpression was significantly related to DM (P = .02) and OM (P = .003), and Ki-67 overexpression was significantly related to DM (P < .0001), CSM (P = .0007), and OM (P = .01). P53 overexpression was significantly related to OM (P = .02). When considered in combination, the overexpression of both Ki-67 and MDM2 at high levels was associated with significantly increased failure rates for all end points (P < .001 for DM, CSM, and OM). CONCLUSION Combined MDM2 and Ki-67 expression levels were independently related to distant metastasis and mortality and, if validated, could be considered for risk stratification of patients with prostate cancer in clinical trials.

Downregulation of vascular endothelial growth factor and induction of tumor dormancy by 15-lipoxygenase-2 in prostate cancer.

The enzyme 15-lipoxygenase-2 (15-LOX-2) utilizes arachidonic acid, a polyunsaturated fatty acid, to synthesize 15(S)-hydroxyeicosatetraenoic acid. Abundantly expressed in normal prostate epithelium but frequently suppressed in the cancerous tissues, 15-LOX-2 has been suggested as a functional suppressor of prostate cancer, but the mechanism(s) involved remains unknown. To study the functional role of 15-LOX-2 in prostate cancer, we expressed 15-LOX-2 as a fusion protein with GFP in DU145 and PC-3 cells and found that 15-LOX-2 increased cell cycle arrest at G0/G1 phase. When injected into athymic nu/nu mice, prostate cancer cells with 15-LOX-2 expression could still form palpable tumors without significant changes in tumorigenicity. But, the tumors with 15-LOX-2 expression grew significantly slower than those derived from vector controls and were kept dormant for a long period of time. Histological evaluation revealed an increase in cell death in tumors derived from prostate cancer cells with 15-LOX-2 expression, while in vitro cell culture conditions, no such increase in apoptosis was observed. Further studies found that the expression of vascular endothelial growth factor A (VEGF-A) was significantly reduced in prostate cancer cells with 15-LOX-2 expression restored. Our studies suggest that 15-LOX-2 suppresses VEGF gene expression and sustains tumor dormancy in prostate cancer. Loss of 15-LOX-2 functionalities, therefore, represents a key step for prostate cancer cells to exit from dormancy and embark on malignant progression in vivo.

Thromboxane A2 receptors in prostate carcinoma: expression and its role in regulating cell motility via small GTPase Rho.

Thromboxane A(2) (TxA(2)) is a prostanoid formed by thromboxane synthase using the cyclooxygenase product prostaglandin H(2) as the substrate. Previously, increased expression of thromboxane synthase was found in prostate tumors, and tumor cell motility was attenuated by inhibitors of thromboxane synthase. This study was undertaken to elucidate how tumor motility is regulated by TxA(2). Here, we report that human prostate cancer cells express functional receptors for TxA(2) (TP). Ligand binding assay found that PC-3 cells binded to SQ29548, a high-affinity TP antagonist, in a saturable manner with K(d) of 3.64 nmol/L and B(max) of 120.4 fmol per million cells. Treatment of PC-3 cells by U46619, a TP agonist, induced PC-3 cell contraction, which was blocked by pretreatment with the TP antagonist SQ29548 or pinane TxA(2). The migration of prostate cancer cells was significantly inhibited either by sustained activation of TP or by blockade of TP activation, suggesting that TP activation must be tightly controlled during cell migration. Further studies found that small GTPase RhoA was activated by TP activation, and pretreatment of PC-3 cells with Y27632, a Rho kinase (ROCK) inhibitor, blocked U46619-induced cell contraction. A dominant-negative mutant of RhoA also blocked U46619-induced cell contraction. Taken together, the data suggest that TPs are expressed in prostate cancer and activation of TPs regulates prostate cancer cell motility and cytoskeleton reorganization through activation of Rho.

Prognostic value of abnormal p53 expression in locally advanced prostate cancer treated with androgen deprivation and radiotherapy: a study based on RTOG 9202.

PURPOSE: The goal of this study was to verify the significance of p53 as a prognostic factor in Radiation Therapy Oncology Group 9202, which compared short-term androgen deprivation (STAD) with radiation therapy (RT) to long-term androgen deprivation + RT in men with locally advanced prostate cancer (Pca). METHODS AND MATERIALS: Tumor tissue was sufficient for p53 analysis in 777 cases. p53 status was determined by immunohistochemistry. Abnormal p53 expression was defined as 20% or more tumor cells with positive nuclei. Univariate and multivariate Cox proportional hazards models were used to evaluate the relationships of p53 status to patient outcomes. RESULTS: Abnormal p53 was detected in 168 of 777 (21.6%) cases, and was significantly associated with cause-specific mortality (adjusted hazard ratio [HR] = 1.89; 95% confidence interval (CI) 1.14 - 3.14; p = 0.014) and distant metastasis (adjusted HR = 1.72; 95% CI 1.13-2.62; p = 0.013). When patients were divided into subgroups according to assigned treatment, only the subgroup of patients who underwent STAD + RT showed significant correlation between p53 status and cause-specific mortality (adjusted HR = 2.43; 95% CI = 1.32-4.49; p = 0.0044). When patients were divided into subgroups according to p53 status, only the subgroup of patients with abnormal p53 showed significant association between assigned treatment and cause-specific mortality (adjusted HR = 3.81; 95% CI 1.40-10.37; p = 0.0087). CONCLUSIONS: Abnormal p53 is a significant prognostic factor for patients with prostate cancer who undergo short-term androgen deprivation and radiotherapy. Long-term androgen deprivation may significantly improve the cause-specific survival for those with abnormal p53.

In vitro and in vivo molecular evidence for better therapeutic efficacy of ABT-627 and taxotere combination in prostate cancer.

Bone is the key metastatic site for prostate cancer. Endothelin 1 (ET-1) produced abundantly by prostate cancer cells binds to its receptor present on bone marrow stromal cells and favors osteoblastic response during bone metastases of prostate cancer. This suggests that interrupting ET-1 interaction with its endothelin A (ET(A)) receptor could be useful for inhibiting prostate cancer bone metastasis and, as such, may enhance the therapeutic activity of docetaxel (Taxotere), the most commonly used drug for the treatment of metastatic prostate cancer. Therefore, the goal of our study was to obtain preclinical data supporting our hypothesis that the combined use of ET(A) receptor antagonist (ABT-627; Atrasentan) with Taxotere will be superior in inducing apoptosis in vitro and inhibiting tumor growth in vivo in a SCID-hu model of experimental bone metastasis induced by C4-2b prostate cancer cells. In vitro studies were done on a panel of prostate cancer cell lines to understand the molecular basis of combination therapy, and we found that the combination was more effective in the inhibition of cell viability and induction of apoptosis in LNCaP and C4-2b cells (androgen receptor positive) but not in PC-3 cells. These results were correlated with inactivation of Akt/nuclear factor-kappaB and its target genes. For in vivo studies, the therapeutic regimen was initiated when the tumor began showing signs of growth and treatment was continued for 5 weeks. Tumor volume and serum prostate-specific antigen were used as terminal index to evaluate the therapeutic advantage of combination therapy relative to a single regimen and untreated control. At termination, we found a 90% reduction in tumor volume by combination treatment relative to the untreated control group. Most importantly, the antitumor activity was associated with the down-regulation of molecular markers in tumor tissues that were similar to those observed in vitro.

Soy isoflavones enhance radiotherapy in a metastatic prostate cancer model.

We previously reported that genistein, the bioactive isoflavone of soybeans, acts as a radiosensitizer for prostate cancer. Pretreatment of tumor cells with genistein potentiated radiation-induced killing in vitro and in orthotopic models in vivo. However, pure genistein promoted increased lymph node metastasis, when administered alone in vivo. We investigated in vitro and in vivo the effects of soy isoflavones (genistein, daidzein and glycitein) as soy pills of similar composition are used in human interventions but not pure genistein. Soy isoflavones inhibited cell survival and potentiated radiation cell killing in PC-3 tumor cells, in vitro. Increased cell killing correlated with inhibition of antiapoptotic molecules Bcl-xL and survivin, upregulation of proapoptotic Bax molecule and PARP cleavage, suggesting activation of apoptotic pathways. In vivo, using the PC-3 orthotopic metastatic mouse model, soy isoflavones and prostate tumor irradiation led to enhanced control of primary tumor growth and metastasis, as observed with pure genistein and radiation. Interestingly, treatment with soy isoflavones did not increase metastasis to para-aortic lymph nodes in contrast to the consistent increase caused by pure genistein. Histologically prostate tumors, treated with soy isoflavones and radiation, showed tumor destruction and in situ tissue alterations, comparable with genistein and radiation effects. However, genistein, but not soy isoflavones, caused induction of HIF1-alpha in prostate tumors, suggesting that induction of hypoxia by pure genistein could contribute to increased metastasis. Our studies demonstrate the safety and potential role of soy isoflavones for enhancing the therapeutic effect of radiotherapy in prostate cancer.

Progression of renal cell carcinoma is inhibited by genistein and radiation in an orthotopic model.

BACKGROUND: We have previously reported the potentiation of radiotherapy by the soy isoflavone genistein for prostate cancer using prostate tumor cells in vitro and orthotopic prostate tumor models in vivo. However, when genistein was used as single therapy in animal models, it promoted metastasis to regional para-aortic lymph nodes. To clarify whether these intriguing adverse effects of genistein are intrinsic to the orthotopic prostate tumor model, or these results could also be recapitulated in another model, we used the orthotopic metastatic KCI-18 renal cell carcinoma (RCC) model established in our laboratory. METHODS: The KCI-18 RCC cell line was generated from a patient with papillary renal cell carcinoma. Following orthotopic renal implantation of KCI-18 RCC cells and serial in vivo kidney passages in nude mice, we have established a reliable and predictable metastatic RCC tumor model. Mice bearing established kidney tumors were treated with genistein combined with kidney tumor irradiation. The effect of the therapy was assessed on the primary tumor and metastases to various organs. RESULTS: In this experimental model, the karyotype and histological characteristics of the human primary tumor are preserved. Tumor cells metastasize from the primary renal tumor to the lungs, liver and mesentery mimicking the progression of RCC in humans. Treatment of established kidney tumors with genistein demonstrated a tendency to stimulate the growth of the primary kidney tumor and increase the incidence of metastasis to the mesentery lining the bowel. In contrast, when given in conjunction with kidney tumor irradiation, genistein significantly inhibited the growth and progression of established kidney tumors. These findings confirm the potentiation of radiotherapy by genistein in the orthotopic RCC model as previously shown in orthotopic models of prostate cancer. CONCLUSION: Our studies in both RCC and prostate tumor models demonstrate that the combination of genistein with primary tumor irradiation is a more effective and safer therapeutic approach as the tumor growth and progression are inhibited both in the primary and metastatic sites.

In vitro and in vivo molecular evidence of genistein action in augmenting the efficacy of cisplatin in pancreatic cancer.

We recently reported the potential of genistein in augmenting gemcitabine-induced killing of pancreatic cancer (Banerjee, S. et al., Cancer Research 2005;65:9064-72). Since cis-diaminedichloroplatinum (II) (cisplatin) is widely used against solid tumors, we further investigated whether genistein pretreatment could be used as a novel strategy for cisplatin-induced killing of pancreatic cancer cells in vitro and enhanced antitumor activity in vivo. Our in vitro results showed that pretreatment of cells with genistein followed by cisplatin resulted in significant loss of cell viability and potentiated apoptosis irrespective of the metastatic ability of cells. Mechanistically, genistein augmented cisplatin induced killing by down regulating transcription factor-NF-kappaB and anti-apoptotic Akt expression. NF-kappaB was found upregulated when pancreatic cancer cells were exposed to cisplatin, suggesting the potential mechanism of acquired chemo-resistance. In addition, we also showed, for the first time, that genistein in combination with cisplatin is more effective antitumor agent in our orthotopic tumor model. But most importantly, our data also showed that a specific target, such as NF-kappaB, was inactivated in animal tumors treated with genistein and cisplatin. Immunohistochemical data showed reduced staining for phospho-p65, Bcl-xL and MMP-9 in treated tumors compared to control tumors, but the lowest activity was seen in the combination group. These results provide strong molecular in vivo evidence in support of our hypothesis that inactivation of the NF-kappaB signaling pathway by genistein results in the chemo-sensitization of pancreatic tumors to cisplatin, which is likely to be an important and novel strategy for the treatment of pancreatic cancer.

Prostate cancer treatment is enhanced by genistein in vitro and in vivo in a syngeneic orthotopic tumor model.

Pretreatment with genistein, a bioactive component of soy isoflavones, potentiated cell killing induced by radiation in human PC-3 prostate cancer cells in vitro. Using an orthotopic xenograft in nude mice, we demonstrated that genistein combined with prostate tumor irradiation caused greater inhibition of primary tumor growth and increased control of spontaneous metastasis to para-aortic lymph nodes, increasing mouse survival. Paradoxically, treatment with genistein alone increased metastasis to lymph nodes. This observation is of concern in relation to soy-based clinical trials for cancer patients. To address whether this observation is because nude mice have an impaired immune system, these studies were repeated in orthotopic RM-9 prostate tumors in syngeneic C57BL/6 mice. The combination of genistein with radiation in this model also caused a greater inhibition of primary tumor growth and spontaneous metastasis to regional para-aortic lymph nodes, whereas treatment with genistein alone showed a trend to increased lymph node metastasis. Data from the syngeneic and xenograft models are comparable and indicate that the combination of genistein with radiotherapy is more effective and safer for prostate cancer treatment than genistein alone, which promotes metastatic spread to regional lymph nodes.

Antitumor activity of epidermal growth factor receptor-related protein is mediated by inactivation of ErbB receptors and nuclear factor-kappaB in pancreatic cancer.

The erbB family of receptor tyrosine kinases plays critical roles in human cancers, including pancreatic cancer. Discovering a specific agent, which targets multiple members of the erbB family, would be important in pancreatic cancer therapy. Recently, we isolated a novel negative regulator of epidermal growth factor receptor (EGFR), termed EGFR-related protein (ERRP), whose expression attenuates EGFR activation. In the current study, we examined the effects of recombinant ERRP on the growth and ligand-induced activation of multiple members of erbB family in three pancreatic cancer cell lines that express varying levels of EGFR and other member(s) of its family, specifically HER-2. Additionally, we compared the growth inhibitory effect of ERRP with that of Erbitux or Herceptin. Our results showed that ERRP is most effective in inhibiting proliferation of BxPC-3, HPAC, and PANC-1 pancreatic cancer cells. ERRP also inhibited ligand-induced activation of EGFR, HER-2, and HER-3 (ErbB3). In contrast, Erbitux and Herceptin only partially or modestly inhibited activation of EGFR, HER-2, and HER-3. Most importantly, ERRP was found to inhibit pancreatic tumor growth in a severe combined immunodeficient mouse xenograft model. The antitumor activity of ERRP correlates well with tumor differentiation and down-regulation of nuclear factor-kappaB activity. In summary, our results suggest that ERRP is an effective pan-erbB inhibitor, which could be a potential therapeutic agent for pancreatic cancers expressing different levels and subclasses of erbB family of proteins.

A proposal for a new and more practical grading scheme for pancreatic ductal adenocarcinoma.

There is no uniformly applied grading system for pancreatic ductal adenocarcinoma (DA). The scheme advocated by the WHO is essentially that of Kloppel et al, and is based on the "highest grade" focus. Although it is precise with good prognostic value, it is unfortunately not widely applied, largely because of the lack of recognition and partly because of its complex nature (interpretation of multiple parameters). Furthermore, it is fundamentally different from the one used in Japan, which evaluates the overall pattern. To establish a more widely applicable, practical, and clinically relevant grading system, a scheme similar to Gleason's scoring system was developed and tested on 112 cases of resected pancreatic DA and was compared with the WHO system. In the grading system devised, patterns (P) of infiltration were classified as follows: P1, well-defined glands with easily discernible contours; P2, fused or poorly formed glands with ill-defined contours; P3, nonglandular patterns. A score was then obtained by the summation of the predominant and the secondary patterns. Scores < or =3 (at least some well-formed glands and no nonglandular pattern) was graded as G1, 4 as G2, and > or =5 (at least some nonglandular patterns and no well-formed glandular pattern) as G3. Seventy-three percent of the cases displayed mixed patterns, with disparate patterns (P1 with P3) in 13%, confirming the high degree of heterogeneity of DA. There was a significant correlation between grade and survival, better than the correlation between survival and either the major or minor patterns evaluated separately. The median survival for G1, G2, and G3 were 22, 14, and 8 months; 1-year survival 68%, 44%, and 33%; 2-year was 67%, 11%, and 0%; and 3-year was 23%, 4%, and 0%, respectively (P = 0.0019). In a multivariate analysis, correlating survival with grade, tumor size, and lymph node status, the grade was the strongest independent predictor of survival. Odds ratio of dying of disease were 3.56 (P < 0.0001) in G3 versus G1, 1.79 (P = 0.058) in G2 versus G1, and 1.98 (P = 0.03) in G3 versus G2. Compared with this, the same odds ratio were 1.17 (P = 0.01) in tumors >2 cm versus < or =2 cm and 1.78 (P = 0.01) in cases with positive versus negative lymph nodes. The WHO grading scheme was not found to have as good a correlation with survival in this study, with WHO grade 2 showing a better survival than 1. The reproducibility of both the proposed grading system and that of WHO were found to be moderately good (with kappa values of 0.43 and 0.44, respectively), when 32 slides of DA were graded by four independent observers. The grading scheme for pancreatobiliary adenocarcinoma proposed here is highly applicable because it is practical and readily adoptable. It reflects biologic characteristics of ductal carcinoma (prominent tubule formation and tumor heterogeneity). Most importantly, it is clinically relevant with good prognostic value. Lastly, it is also applicable for use in research, by utilizing "patterns," even in small specimens like microarrays or biopsies.

Clear cell renal cell carcinoma.

Clear cell RCC is the most common type of RCC that occurs in adults. It has the worst prognosis among the common epithelial tumors of the kidney. Histologically, a wide range of morphologic patterns can be encountered. Those cases with a multi-locular cystic architecture are considered to be a distinct subtype because of the clinicopathologic features.

Handling and reporting of tumor-containing kidney specimens.

The pathologic features of RCC are the most valuable factors in predicting the prognosis and for planning surveillance and treatment protocols. Urologists and pathologists should optimize approaches in handling tumor-containing kidney specimens to allow for the best evaluation and reporting of such specimens. A pathologic report of a tumor-containing kidney specimen should include all established or potential prognostic factors, especially tumor types, size, grade, information for pathologic staging, and status of the surgical margin.

Matrix metalloproteinase activity and osteoclasts in experimental prostate cancer bone metastasis tissue.

Previously, we and others showed that broad spectrum pharmaceutical inhibition of matrix metalloproteinase (MMP) activity reduces intraosseous tumor burden and bone degradation in animal models of bone metastasis. Herein, we used specific assays to measure net enzymatic activities of individual MMPs during colonization of bone by prostate cancer cells. PC3 cells were injected into the marrow of human fetal femurs previously implanted in SCID mice. Net MMP-9 activity in bone tissues peaked 2 weeks after injection, coinciding with a wave of osteoclast recruitment. In contrast, MMP-2 and MT1-MMP activity did not change. In vitro, co-culture of PC3 cells with bone tissue led to activation of pro-MMP-9 and increases in secreted net MMP-9 activity. Activation of pro-MMP-9 was prevented by metalloprotease inhibitors but not by inhibitors of other classes of proteases. Ribozyme suppression of MMP-9 expression in PC3 cells did not affect pro-MMP-9 activation or net MMP-9 activity and did not affect the phenotype of bone tumors. siRNA targeting of MMP-9 expression in preosteoclasts in vitro demonstrated that tumor-induced preosteoclast motility was dependent on MMP-9 expression. These data suggest that osteoclast-derived MMP-9 may represent a potential therapeutic target in bone metastasis and provide a rationale for the development of MMP-9-specific inhibitors.

Expression of cyclooxygenase-2 in advanced stage ovarian serous carcinoma: correlation with tumor cell proliferation, apoptosis, angiogenesis, and survival.

OBJECTIVE: Cyclo-oxygenase-2 seems to be involved at various steps in the processes of tumor progression. The objective of this study was to examine the relationship between cyclo-oxygenase-2 expression and tumor proliferation, apoptosis and angiogenesis in patients with advanced stage high-grade ovarian carcinoma. STUDY DESIGN: Specimens from 118 patients with high-grade and advanced stage (III, IV) serous ovarian carcinoma were evaluated by immunohistochemistry for cyclo-oxygenase-2, Ki-67, vascular endothelial growth factor, and bcl-2 expression. Tumor microvessel density was assessed with CD34 immunostaining. We investigated the relationships between cyclo-oxygenase-2 expression and clinicopathologic characteristics, tumor angiogenesis (tumor microvessel density and vascular endothelial growth factor expression), and tumor proliferation and apoptosis. The effect of cyclooxygenase-2 expression on patient survival was determined. RESULTS: There was a significant positive correlation between cyclo-oxygenase-2 expression in tumor cells and markers of tumor proliferation and angiogenesis. In univariate survival analysis, high cyclo-oxygenase-2 and high Ki-67 expression showed a significant impact of on patient survival (P < .001). In multivariate regression analysis, only Ki-67 expression retained its significance as an independent poor prognostic factor (death hazard ratio, 2.0; 95% CI, 1.2-3.3; P < .001). CONCLUSION: Expression of cyclo-oxygenase-2 correlates with tumor proliferation and tumor angiogenesis but not with apoptotic markers (bcl-2 expression) in high-grade, advanced-stage serous ovarian carcinoma.

Curative antitumor immune response is optimal with tumor irradiation followed by genetic induction of major histocompatibility complex class I and class II molecules and suppression of Ii protein.

Transfecting genes into tumors, to upregulate major histocompatibility complex (MHC) class I and class II molecules and inhibit MHC class II associated invariant chain (Ii), induces a potent anti-tumor immune response when preceded by tumor irradiation, in murine RM-9 prostate carcinoma. The transfected genes are cDNA plasmids for interferon-gamma (pIFN-gamma), MHC class II transactivator (pCIITA), an Ii reverse gene construct (pIi-RGC), and a subtherapeutic dose of adjuvant IL-2 (pIL-2). Responding mice rejected challenge with parental tumor and demonstrated tumor-specific cytotoxic T lymphocytes (CTLs). We have extended our investigation to determine the relative roles of each one of the four plasmids pIFN-gamma, pCIITA, pIi-RGC, and pIL-2 in conjunction with radiation for the induction of a curative immune response. Upregulation of MHC class I with pIFN-gamma or class II with pCIITA, separately, does not lead to a complete response even if supplemented with pIL-2 or pIi-RGC. An optimal and specific antitumor response is achieved in more than 50% of the mice when, after tumor irradiation, tumor cells are converted in situ to a MHC class I+/class II+/Ii- phenotype with pIFN-gamma, pCIITA, pIi-RGC, and pIL-2. We demonstrate further that both CD4+ helper T cells and CD8+ cytotoxic T cells are essential for induction of an antitumor response because in vivo depletion of either subset abrogates the response. The radiation contributes to the gene therapy by causing tumor debulking and increasing the permeability of tumors to infiltration of inflammatory cells.

Genistein potentiates inhibition of tumor growth by radiation in a prostate cancer orthotopic model.

OBJECTIVE: We have shown previously that pretreatment with genistein potentiated cell killing induced by radiation in human PC-3 prostate carcinoma cell line in vitro. We tested this approach in vivo using an orthotopic prostate carcinoma model of PC-3 cells in nude mice. METHODS: Established prostate tumors were pretreated with p.o. genistein at a dose of 5 mg/d for 2 days followed by tumor irradiation with 5 Gy photons. One day after radiation, genistein was resumed and given every other day for 4 weeks. RESULTS: Genistein combined with radiation caused a significantly greater inhibition of primary tumor growth (87%) compared with genistein (30%) or radiation (73%) alone. The number of metastatic lymph nodes was also significantly decreased following genistein and radiation. Paradoxically, genistein alone increased the size of lymph nodes associated with heavy tumor infiltration. Genistein-treated prostate tumors were large with necrosis, apoptotic cells, and giant cells and have a lower proliferation index than in control tumors. Following radiation, areas of tumor destruction replaced by fibrotic tissue and inflammatory cells as well as giant cells were observed, which are typical of radiation effect. After radiation and genistein treatment, an increase in giant cells, apoptosis, inflammatory cells, and fibrosis was observed with decreased tumor cell proliferation consistent with increased tumor cell destruction. Long-term therapy with genistein after prostate tumor irradiation significantly increased survival. CONCLUSIONS: Genistein combined with prostate tumor irradiation led to a greater control of the growth of the primary tumor and metastasis to lymph nodes than genistein or radiation alone, resulting in greater survival.

Regulation of gene expression and inhibition of experimental prostate cancer bone metastasis by dietary genistein.

Prostate cancer frequently metastasizes to the bone, and the treatment outcome for metastatic prostate cancer has been disappointing so far. Dietary genistein, derived primarily from soy product, has been proposed to be partly responsible for the low rate of prostate cancer in Asians. Our previous studies have shown that genistein elicits pleiotropic effects on prostate cancer cells, but there are no studies documenting comprehensive gene expression profiles and antitumor effects of dietary genistein on human prostate cancer grown in human bone environment. In this study, we investigated the effects of genistein on PC3 prostate cancer cells and experimental PC3 bone tumors created by injecting PC3 cells into human bone fragments previously implanted in severe combined immunodeficient (SCID) mice (SCID human model). We found that genistein significantly inhibited PC3 bone tumor growth using both prevention and intervention strategies. By using microarray and real-time polymerase chain reaction technology, we found that genistein regulated the expression of multiple genes involved in the control of cell growth, apoptosis, and metastasis both in vitro and in vivo. For example, the expression of various metalloproteinases (MMPs) in PC3 bone tumors was inhibited by genistein treatment, whereas osteoprotegerin was upregulated. MMP immunostaining and transfection experiments also demonstrated that MMP-9 expression was inhibited in PC3 cells in vitro and PC3 bone tumors in vivo after genistein treatment. These results, particularly the in vivo results, demonstrate that dietary genistein may inhibit prostate cancer bone metastasis by regulating metastasis-related genes. Genistein may thus be a promising agent for the prevention and/or treatment of prostate cancer.

Disseminated malignant solitary fibrous tumor of the pleura.

Solitary fibrous tumor (SFT) of the pleura typically forms a localized pleura-based mass, and most are benign. A rare case of disseminated malignant SFT of the pleura is reported. The patient was a 71-year-old man who presented with complaints of shortness of breath to his primary care physician. A diagnosis of malignant mesothelioma was suspected, based on clinical, radiological and needle biopsy findings. He was referred to our institution for surgery. An extrapleural pneumonectomy, encompassing all pleural masses, was performed. Gross examination of the resected specimen was remarkable for numerous masses, ranging in size from 0.2 to 13.5 cm, covering the majority of the visceral pleura. Histologically, the tumor was composed of short spindle cells admixed with variable proportions of collagenous stroma. There were great intra- and intertumoral heterogeneity in tumor growth pattern, cellularity, pleomorphism and mitoses. Histologically malignant areas were present in all of the masses examined. The neoplastic cells were diffusely and intensely positive for bcl-2. Most tumor cells were also strongly stained for CD34 and CD99. Staining for cytokeratin was negative. The tumor also revealed p53 over-expression. Thus, the histological and immunohistochemical features of the tumor were consistent with a disseminated malignant SFT. This report shows that SFT rarely presents with disseminated pleural involvement, and a panel with CD34, bcl-2 and cytokeratin are valuable for differentiating SFT from malignant mesothelioma and other malignant spindle cell neoplasms of the pleura.