Mechanisms of liposomal all-{\it trans\/} retinoic acid and vitamin D3 induced inhibition of cell proliferation and stimulation of apoptosis in aggressive B-cell non-Hodgkin's lymphoma

The Non-Hodgkin's Lymphoma (NHLs) are neoplasms of the immune system. Currently, less than 1% of the etiology of the 22,000 newly diagnosed lymphoma cases in the U.S.A. every year is known. This disease has a significant prevalence and high mortality rate. Cell growth in lymphomas has been shown to be an important parameter in aggressive NHL when establishing prognosis, as well as an integral part in the pathophysiology of the disease process. While many aggressive B cell NHLs respond initially to chemotherapeutic regimens such as CHOP-bleo (adriamycin, vincristine and bleomycin) etc., relapse is common, and the patient is then often refractory to further salvage treatment regimens.^ To assess their potential to inhibit aggressive B cell NHLs and induce apoptosis (also referred to as programmed cell death (PCD)), it was proposed to utilize the following biological agents-liposomal all-trans retinoic acid (L-ATRA) which is a derivative of Vitamin A in liposomes and Vitamin D3. Preliminary evidence indicates that L-ATRA may inhibit cell growth in these cells and may induce PCD as well. Detailed studies were performed to understand the above phenomena by L-ATRA and Vitamin D3 in recently established NHL-B cell lines and primary cell cultures. The gene regulation involved in the case of L-ATRA was also delineated. ^

Integrin mediated growth and apoptosis in human gastric adenocarcinoma

Integrins are important as the primary cell adhesion molecule providing information about the extracellular microenvironment to the interior of the cell to influence cellular behavior such as differentiation, proliferation and apoptosis. Apoptotic death due to loss of adhesion is termed anoikis. In this study we have obtained a parental human gastric adenocarcinoma cell line that yielded two variant lines that had differing responses to lack of adhesion. The STAD.APO cell line undergoes apoptosis when denied adherence and the STAD.ARR cell line enters into cell cycle arrest under the identical suspended conditions. We have shown that cyclin A and cyclin D mRNA and protein are down regulated when cells are denied adherence for 24 hours in tissue culture wells previously coated with poly-HEMA. To test whether cyclin A was able to rescue cells from cell cycle arrest and/or anoikis by overriding the cell cycle machinery we transfected the full length cDNA in to each cell type. Surprisingly we found that anoikis and cell cycle arrest due to suspended conditions was not affected by overexpression of cyclin A protein, but that growth under adhered conditions was reduced compared to vector alone control transfectants. Further, we transfected other cell lines; ST7, gastric cancer, MDA-MB-4.35, breast cancer, and HPB T-cell leukemic and in no case were suspended culturing conditions overcome by cyclin A. This result indicates an additional level of regulation for the cell cycle machinery. Additionally, soluble collagen was shown to be able to save from anoikis and also from cell cycle arrest while the β1 specific mAb 33B6 was only able to save from anoikis. Immunofluorescent studies show that soluble collagen creates clusters of β1 with FAK and also β1 with actin in the STAD.ARR cells but does not in the STAD.APO cells. This result indicates that the phenotypes under suspended conditions between these cell lines may diverge at their requirements for integrin ligation. Additionally we characterized the nature of anoikis by showing cytochrome c release, caspase 3, p21 and p53 activation in STAD.APO cells. Thus, our results have implications in the understanding of integrin biology and neoplastic progression. ^

Risk of second primary tumors following treatment of non-small cell lung cancer

Background. The rise in survival rates along with more detailed follow-up using sophisticated imaging studies among non-small lung cancer (NSCLC) patients has led to an increased risk of second primary tumors (SPT) among these cases. Population and hospital based studies of lung cancer patients treated between 1974 and 1996 have found an increasing risk over time for the development of all cancers following treatment of non-small cell lung cancer (NSCLC). During this time the primary modalities for treatment were surgery alone, radiation alone, surgery and post-operative radiation therapy, or combinations of chemotherapy and radiation (sequentially or concurrently). There is limited information in the literature about the impact of treatment modalities on the development of second primary tumors in these patients. ^ Purpose. To investigate the impact of treatment modalities on the risk of second primary tumors in patients receiving treatment with curative intent for non-metastatic (Stage I–III) non-small cell lung cancer (NSCLC). ^ Methods. The hospital records of 1,095 NSCLC patients who were diagnosed between 1980–2001 and received treatment with curative intent at M.D. Anderson Cancer Center with surgery alone, radiation alone (with a minimum total radiation dose of at least 45Gy), surgery and post-operative radiation therapy, radiation therapy in combination with chemotherapy or surgery in combination with chemotherapy and radiation were retrospectively reviewed. A second primary malignancy was be defined as any tumor histologically different from the initial cancer, or of another anatomic location, or a tumor of the same location and histology as the initial tumor having an interval between cancers of at least five years. Only primary tumors occurring after treatment for NSCLC will qualified as second primary tumors for this study. ^ Results. The incidence of second primary tumor was 3.3%/year and the rate increased over time following treatment. The type of NSCLC treatment was not found to have a striking effect upon SPT development. Increased rates were observed in the radiation only and chemotherapy plus radiation treatment groups; but, these increases did not exceed expected random variation. Higher radiation treatment dose, patient age and weight loss prior to index NSCLC treatment were associated with higher SPT development. ^

Proteolytic mechanisms of cell injury following glucose -oxygen deprivation in primary neuronal cultures

Researchers have historically emphasized the contribution of caspase-3 to apoptotic but not necrotic cell death, while calpain has been implicated primarily in necrosis and, to a lesser extent, in apoptosis. Activation of these proteases occurs in vivo following various CNS insults including ischemia. In addition, both necrotic and apoptotic cell death phenotypes are detected following ischemia. However, the contributions of calpain and caspase-3 to apoptotic and necrotic cell death phenotypes following CNS insults are relatively unexplored. To date, no study has examined the concurrent activation of calpain and caspase-3 in necrotic and apoptotic cell death phenotypes following any CNS insult. The present study employed oxygen-glucose deprivation (OGD) to determine the relative contributions of caspase-3 and calpain to apoptotic and necrotic cell death following OGD. Experiments characterized a model of OGD by evaluating cell viability and characterizing the cell death phenotypes following OGD in primary septo-hippocampal co-cultures. Furthermore, cell markers (NeuN and MAP2 or GFAP) assessed the effects of OGD on neuronal and astroglial viability, respectively. In addition, calpain and caspase-3 mediated proteolysis of α-spectrin was examined using Western blot techniques. Activation of these proteases in individual cells phenotypically characterized as apoptotic and necrotic was also evaluated by using antibodies specific for calpain or caspase-3 mediated breakdown products to α-spectrin. Administration of appropriate caspase-3 and calpain inhibitors also examined the effects of protease inhibition on cell death. OGD produced prominent expression of apoptotic cell death phenotypes primarily in neurons, with relatively little damage to astroglia. Although Western blot data suggested greater proteolysis of α-spectrin by calpain than caspase-3, co-activation of both proteases was usually detected in cells exhibiting apoptotic or necrotic cell death phenotypes. While inhibition of calpain and caspase-3 activity decreased LDH release following OGD, it was not clear whether this effect was also associated with a decrease in cell death and the appearance of apoptotic cell death phenotypes. These data demonstrate that both calpain and caspase-3 contribute to the expression of apoptotic cell death phenotypes following OGD, and that calpain could potentially have a larger role in the expression of apoptotic cell death than previously thought. ^

K1 protein of human herpesvirus 8 suppresses lymphoma cell Fas-mediated apoptosis.

Expression of the K1 gene of human herpesvirus 8 activates nuclear factor-kappaB and induces lymph node hyperplasia and lymphomas in transgenic mice. To further delineate its role in cell survival, we determined whether K1 altered apoptosis of lymphoma cells. K1 protein is expressed in Kaposi sarcoma and primary effusion lymphoma. We retrovirally transfected BJAB lymphoma, THP-1, U937, and Kaposi sarcoma SLK cells to express K1 and a K1 mutant with the deleted immunoreceptor tyrosine-based activation motif (K1m). We challenged cells with an agonistic anti-Fas antibody, Fas ligand, irradiation, and tumor necrosis factor-related apoptosis-inducing ligand. K1 transfectants but not K1m transfectants exhibited reduced levels of apoptosis induced by the anti-Fas antibody but not apoptosis induced by the tumor necrosis factor-related apoptosis-inducing ligand or irradiation. K1 expression resulted in reduced apoptosis rates as shown in several assays. K1 induced a modest reduction in levels of Fas-associated death domain protein, and procaspase 8 recruited to the death-inducing signaling complex. Finally, K1 transfectants cleaved procaspase 8 at significantly lower rates than did K1m transfectants. K1-transfected mice, compared with vector-transfected mice, showed lower death rates after challenge with anti-Fas antibody. K1 may contribute to lymphoma development by stimulating cell survival by selectively blocking Fas-mediated apoptosis.

ROLE OF GSH METABOLISM IN MEDIATING STROMAL-LEUKEMIA INTERACTION AND PROMOTING CELL SURVIVAL AND DRUG RESISTANCE IN CHRONIC LYMPHOCYTIC LEUKEMIA

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the western countries. The interaction between CLL cells and the bone marrow stromal environment is thought to play a major role in promoting the leukemia cell survival and drug resistance. My dissertation works proved a novel biochemical mechanism by which the bone marrow stromal cells exert a profound influence on the redox status of primary CLL cells and enhance their ability to sustain oxidative stress and drug treatment. Fresh leukemia cells isolated from the peripheral blood of CLL patients exhibited two major redox alterations when they were cultured alone: a significant decrease in cellular glutathione (GSH) and an increase in basal ROS levels. However, when cultured in the presence of bone marrow stromal cells, CLL cells restored their redox balance with an increased synthesis of GSH, a decrease in spontaneous apoptosis, and an improved cell survival. Further study showed that CLL cells were under intrinsic ROS stress and highly dependent on GSH for survival, and that the bone marrow stromal cells promoted GSH synthesis in CLL cells through a novel biochemical mechanism. Cysteine is a limiting substrate for GSH synthesis and is chemically unstable. Cells normally obtain cysteine by uptaking the more stable and abundant precursor cystine from the tissue environment and convert it to cysteine intracellularly. I showed that CLL cells had limited ability to take up extracellular cystine for GSH synthesis due to their low expression of the transporter Xc-, but had normal ability to uptake cysteine. In the co-culture system, the bone marrow stromal cells effectively took up cystine and reduced it to cysteine for secretion into the tissue microenvironment to be taken up by CLL cells for GSH synthesis. The elevated GSH in CLL cells in the presence of bone marrow stromal cells significantly protected the leukemia cells from stress-induced apoptosis, and rendered them resistant to standard therapeutic agents such as fludarabine and oxaliplatin. Importantly, disabling of this protective mechanism by depletion of cellular GSH using a pharmacological approach potently sensitized CLL cells to drug treatment, and effectively enhanced the cytotoxic action of fludarabine and oxaliplatin against CLL in the presence of stromal cells. This study reveals a key biochemical mechanism of leukemia-stromal cells interaction, and identifies a new therapeutic strategy to overcome drug resistance in vivo.

Transplantation of human embryonic stem cell-derived alveolar epithelial type II cells abrogates acute lung injury in mice.

Respiratory diseases are a major cause of mortality and morbidity worldwide. Current treatments offer no prospect of cure or disease reversal. Transplantation of pulmonary progenitor cells derived from human embryonic stem cells (hESCs) may provide a novel approach to regenerate endogenous lung cells destroyed by injury and disease. Here, we examine the therapeutic potential of alveolar type II epithelial cells derived from hESCs (hES-ATIICs) in a mouse model of acute lung injury. When transplanted into lungs of mice subjected to bleomycin (BLM)-induced acute lung injury, hES-ATIICs behaved as normal primary ATIICs, differentiating into cells expressing phenotypic markers of alveolar type I epithelial cells. Without experiencing tumorigenic side effects, lung injury was abrogated in mice transplanted with hES-ATIICs, demonstrated by recovery of body weight and arterial blood oxygen saturation, decreased collagen deposition, and increased survival. Therefore, transplantation of hES-ATIICs shows promise as an effective therapeutic to treat acute lung injury.

Mechanism of surgical stress impairment of murine natural killer cell cytotoxicity

Natural killer cells may provide an important first line of defense against metastatic implantation of solid tumors. This antitumor function occurs during the intravascular and visceral lodgment phase of cancer dissemination, as demonstrated in small animal metastasis models. The role of the NK cell in controlling human tumor dissemination is more difficult to confirm, at least partially because of ethical restraints on experimental design. Nonetheless, a large number of solid tumor patient studies have demonstrated NK cell cytolysis of both autologous and allogeneic tumors.^ Of the major cancer therapeutic modalities, successful surgery in conjunction with other treatments offers the best possibility of cure. However, small animal experiments have demonstrated that surgical stress can lead to increased rates of primary tumor take, and increased incidence, size, and rapidity of metastasis development. Because the physiologic impact of surgical stress can also markedly impair perioperative antitumor immune function in humans, we examined the effect of surgical stress on perioperative NK cell cytolytic function in a murine preclinical model. Our studies demonstrated that hindlimb amputation led to a marked impairment of postoperative NK cell cytotoxicity. The mechanism underlying this process is complex and involves the postsurgical generation of splenic erythroblasts that successfully compete with NK cells for tumor target binding sites; NK cell-directed suppressor cell populations; and a direct impairment of NK cell recycling capacity. The observed postoperative NK cell suppression could be prevented by in vivo administration of pyrimidinone biologic response modifiers or by short term in vitro exposure of effector cells to recombinant Interleukin-2. It is hoped that insights gained from this research may help in the future development of NK cell specific perioperative immunotherapy relevant to the solid tumor patients undergoing cancer resection. ^

p75 receptor-mediated neurotrophism: A new mechanism of melanoma cell survival and invasion

Trophism as a "clonal dominance" support mechanism for tumor cells is an unexplored area of tumor progression. This report presents evidence that the human melanoma low-affinity neurotrophin receptor (p75) can signal independently of its high-affinity tyrosine kinase counterparts, the TRK family of kinases. Signaling may be accomplished by a p75-associated purine-analog-sensitive kinase and results in enhanced invasion into a reconstituted basement membrane with a corresponding stimulation of matrix metalloproteinase-2 expression. Additionally, a "stress culture" survival assay was developed to mimic the growth limiting conditions encountered by melanoma cells in a rapidly growing primary tumor or metastatic deposit prior to neoangiogenesis. Under these conditions, p75, promotes the survival of high p75 expressing brain-colonizing melanoma cells. Extensive 70W melanoma cell-cell contact, which downregulates p75, immediately precedes the induction of cell death associated with diminished production of two key cell survival factors, bcl-2 and the p85 subunit of phosphoinositol-3-kinase, and an elevation in apoptosis promoting intracellular reactive oxygen species (ROSs). Since one function of bcl-2 may be to control the generation of ROSs via the antioxidant pathway, these cells may receive a apoptosis-prompting "double hit". 70W melanoma cell death occurred by an apoptotic mechanism displaying classical morphological changes including plasma membrane blebbing, loss of microvilli and redistribution of ribosomes. 70W apoptosis could be pharmacologically triggered following anti-p75 monoclonal antibody-mediated clustering of p75 receptors. 70W cells fluorescently sorted for high-p75 expression (p75$\sp{\rm H}$ cells) exhibited an augmented survival potential and a predilection to sort with the S + G2/M growth phase, relative to their low p75 expressing, p75$\sp{\rm L}$ counterparts. Apoptosis is significantly delayed by p75$\sp{\rm H}$ cells, whereas p75$\sp{\rm L}$ cells are exquisitely prone to initiate apoptosis. Importantly, the p75$\sp{\rm L}$ cells that survive apoptosis, highly re-expressed p75 and were remarkably responsive to exogenous NGF.^ These are the first data to implicate p75-mediated neurotrophism as an invasion and survival support mechanism employed by brain-metastatic cells. In particular, these results may have implications in little understood phenomena of tumor progression, such as the emergence of "clonal dominance" and tumor dormancy. ^

Identification of cadmium-induced mutations in a mammalian cell line

Epidemiological studies have shown cadmium to induce cancer in humans, while experimental studies have proven this metal to be a potent tumor inducer in animals. However, cadmium appears nonmutagenic in most prokaryotic and eukaryotic mutagenesis assays. In this study, we present the identification of mutations in normal rat kidney cells infected with the mutant MuSVts110 retrovirus (6m2 cells) as a result of treatment with cadmium chloride. The detection of these mutations was facilitated by the use of a novel mutagenesis assay established in this laboratory. The 6m2 reversion assay is a positive selection system based on the conditional expression of the MuSVts110 v-mos gene. In MuSVts110 the gag and mos genes are fused out of frame, thus the translation of the v-mos sequence requires a frameshift in the genomic RNA. In 6m2 cells this frameshift is accomplished by the temperature-dependent splicing of the primary MuSVts110 transcript. Splicing of MuSVts110, which is mediated by cis-acting sequences, occurs when 6m2 cells are grown at 33$\sp\circ$C and below, but not at 39$\sp\circ$C. Therefore, 6m2 cells appear transformed at low growth temperatures, but take on a morphologically normal appearance when grown at high temperatures. The treatment of 6m2 cells with cadmium chloride resulted in the outgrowth of a number of cells that reverted to the transformed state at high growth temperatures. Analysis of the viral proteins expressed in these cadmium-induced 6m2 revertants suggested that they contained mutations in their MuSVts110 DNA. Sequencing of the viral DNA from three revertants that constitutively expressed the P85$\sp{gag{-}mos}$ transforming protein revealed five different mutations. The Cd-B2 revertant contained three of those mutations: an A-to-G transition 48 bases downstream of the MuSVts110 3$\sp\prime$ splice site, plus a G-to-T and an A-to-T transversion 84 and 100 bases downstream of the 5$\sp\prime$ splice site, respectively. The Cd-15-5 revertant also contained a point mutation, a T-to-C transition 46 bases downstream of the 5$\sp\prime$ splice site, while Cd-10-5 contained a three base deletion of MuSVts110 11 bases upstream of the 3$\sp\prime$ splice site. A fourth revertant, Cd-10, expressed a P100$\sp{gag{-}mos}$ transforming protein, and was found to have a two base deletion. This deletion accomplished the frameshift necessary for v-mos expression, but did not alter MuSVts110 RNA splicing and the expression of p85$\sp{gag{-}mos}.$ Lastly, sequencing of the MuSVts110 DNA from three spontaneous revertants revealed the same G to T transversion in each one. This was the same mutation that was found in the Cd-B2 revertant. These findings provide the first example of mutations resulting from exposure to cadmium and suggest, by the difference in each mutation, the complexity of the mechanism utilized by cadmium to induce DNA damage. ^

Expression and regulation of interleukins in human head and neck squamous cell carcinoma

Patients with head and neck squamous cell carcinoma (HNSCC) demonstrate abnormal cell-mediated immunity which is most pronounced at the primary tumor site. Therefore, we tested whether this aberrant immunity could be due to tumor-derived cytokines. We investigated the presence of cytokine mRNA and protein in 8 HNSCC-derived cell lines; RT-PCR results indicated mRNA's for IL-1$\alpha$ and TGF-$\alpha$ (8/8), TGF-$\beta$ (7/8), IL-1$\beta$ (7/8), IL-4 and IL-6 (4/8). IL-2, IFN-$\gamma,$ and TNF-$\alpha$ mRNA was not detected. Supernatants from 6 of these cell lines were analyzed by ELISA and IL-1$\alpha,$ IL-1$\beta,$ and IL-6 were markedly increased compared to HPV-16 immortalized human oral keratinocytes. IL-1$\alpha$ was found in the highest concentration $>$IL-6 $>$ IL-1$\beta.$^ To approach the mechanisms of cytokine regulation, 4 cell lines were compared for HPV DNA presence, p53 status, and cytokine expression. An association between HPV DNA and cytokine expression was not found. However, cell lines secreting the most IL-6 had mutant p53 and/or HPV 16 E6/E7 expression. Further regulatory investigations revealed that exogenous IL-1$\alpha$ and/or IL-1$\beta$ minimally stimulated the proliferation of 2/3 cell lines, as well as strongly induced IL-6 production in 3/3; this effect was completely abrogated by IL-1Ra. IL-1Ra also inhibited the secretion of IL-1$\alpha$ and IL-1$\beta$ in 2/3 cell lines. These data suggest an IL-1 autocrine loop in certain HNSCC cell lines. Because IL-2 induces IL-1 and is used in therapy of HNSCC, the expression of IL-2 receptor was also investigated; IL-2 $\alpha$ and $\beta$ subunits were detected in 3/3 cell lines and $\gamma$ subunits was detected in one. Exogenous IL-2 inhibited the proliferation, but stimulated the secretion of IL-1$\alpha$ in 2/3, and IL-1$\beta$ and IL-6 in 1/3 cell lines.^ To determine if our cell line findings were applicable to patients, immunohistochemistry was performed on biopsies from 12 invasive tumors. Unexpectedly, universal intracellular production of IL-1$\alpha,$ IL-1$\beta,$ and IL-6 protein was detected. Therefore, the aberrant elaboration of biologically active IL-1 and IL-6 may contribute to altered immune status in HNSCC patients. ^

Molecular analysis of the human $\gamma$-chain T cell receptor genes

In our studies we have focused on the issue of variability and diversity of the $\gamma$ (or $\delta)$ chain T cell receptor (TCR) genes by studying cDNA transcripts in peripheral blood mononuclear cells or $\gamma\delta$ TCR+ T cell clones. The significance of these studies lies in the better understanding of the molecular biology of the $\gamma\delta$ T cell receptor as well as in answering the question whether certain molecular forms predominate in $\gamma\delta$ T cells exhibiting specific immunologic functions. We establish that certain $\gamma$-chain TCR genes exhibit particular patterns of rearrangements in cDNA transcripts in normal individuals. V$\gamma$I subgroup were shown to preferentially rearrange to J$\gamma$2C$\gamma$2 gene segments. These preferential VJC rearrangements, may have implications regarding the potential for diversity and polymorphism of the $\gamma$-chain TCR gene. In addition, the preferential association of V$\gamma$I genes with J$\gamma$2C$\gamma$2, which encode a non-disulfide-linked $\gamma\delta$ TCR, suggests that $\gamma$ chains utilizing V$\gamma$I are predominantly expressed as non-disulfide-linked $\gamma\delta$ TCR heterodimers. The implications of this type of expression remain to be determined. We identified two alternative splicing events of the $\gamma$-chain TCR genes occurring in high frequency in all the normal individuals examined. These events may suggest additional mechanisms of regulation and control as well as diversification of $\gamma\delta$ TCR gene expression. The question whether particular forms of $\gamma$ or $\delta$-chain TCR genes are involved in HLA Class I recognition by specific $\gamma\delta$ cytotoxic T cell clones was addressed. Our results indicated that the T cell clones expressed identical $\gamma$ but distinct $\delta$-chains suggesting that the specificity for recognition of HLA-A2 or HLA-A3 may be conferred by the $\delta$-chain TCR. The issue of the degree of diversity and polymorphism of the $\delta$-chain TCR genes in a patient with a primary immunodeficiency (Omenn's syndrome) was addressed. A limited pattern of rearrangements in peripheral blood transcripts was found, suggesting that a limited $\gamma\delta$ TCR repertoire may be expressed in this particular primary immunodeficiency syndrome. Overall, our findings suggest that $\delta$-chain TCR genes exhibit the potential for significant diversity and that there are certain preferential patterns of expression that may be associated with particular immunologic functions. ^

Effects of galectin-1 and galectin-3 expression on prostate cancer cell adhesion, differentiation, proliferation, and tumorigenicity

The vertebrate $\beta$-galactoside-binding lectins galectin-1 and galectin-3 have been proposed to function in diverse cellular processes such as adhesion, proliferation, differentiation, and tumorigenesis. Experiments were initiated to further study the functional properties of these molecules. A prostate cancer cell line, LNCaP, was identified which expressed neither galectin. This line was stably transfected with cDNA for either galectin-1 or galectin-3. The resultant clones were used to study effects on critical cell processes. LNCaP cells expressing galectin-1 on the surface were found to bind more rapidly than control lines to the human extracellular matrix proteins laminin and fibronectin, although overall binding was not increased. To analyze effects on differentiation, LNCaP cells were studied which had either been transfected with galectin-1 or which had been induced to express endogenous galectin-1 by treatment with the differentiation agent sodium butyrate. In both cases, cells displayed a slower rate of growth and increased rate of apoptosis. A transient decrease in expression of prostate specific antigen was seen in the butyrate treated cells but not in the transfected cells. To investigate the role of galectins in the process of malignant transformation and progression, immunohistochemical analysis was performed on formalin-fixed, paraffin-embedded sections of human prostate tissue, the premalignant lesion prostatic intraepithelial neoplasia, primary adenocarcinoma of the prostate, and foci of metastatic prostate cancer. Galectin-1 expression was relatively constant throughout in contrast to galectin-3 which demonstrated significantly less expression in primary and metastatic tumors. LNCaP cells transfected with galectin-3 cDNA displayed lower proliferation rates, increased spontaneous apoptosis, and G1 growth phase arrest compared to controls. Four of six galectin-3 lines tested were less tumorigenic in nude mice than controls. The following conclusions are drawn regarding the role of galectin-1 and galectin-3 expression in the context of prostate cancer: (1) galectin-1 may participate in the early stages of cancer cell adhesion to extracellular matrix proteins; (2) galectin-1 expression results in a differentiated phenotype and may contribute to differentiation induction by butyrate; (3) galectin-3 expression correlates inversely with prostate cell tumorigenesis and prostate cancer metastasis. ^

Analysis of primary Wilms tumors for WT1 RNA processing alterations

Wilms tumor (WT) is an embryonal renal tumor with a heterogeneous genetic etiology that serves as a valuable model for studying tumorigenesis. Biallelic inactivation of the tumor suppressor gene WT1, a zinc-finger transcriptional regulator located at 11p13, is critical for the development of some Wilms tumors. Interestingly, WT1 genomic analysis has demonstrated mutations in less than 20% of WT cases. This suggests either other genes play a more major role in Wilms tumorigenesis or WT1 is functionally altered by mechanisms other than DNA mutation. Previous observations in rat and in WT xenograft cell lines have suggested that abnormal WT1 RNA processing (exon 6 RNA editing and aberrant exon 2 splicing, respectively) is a potential mechanism of altering WT1 function in the absence of a WT1 DNA mutation. However, the role of this abnormal RNA processing has not previously been assessed in primary Wilms tumors. ^ To test the hypothesis that abnormal WT1 RNA processing is a mechanism of WT1alteration during tumor development, WT1 RNA from 85 primary tumors was analyzed using reverse transcription and polymerase chain reaction amplification (RT-PCR). Although no evidence for WT1 RNA editing was observed, variable levels (5% to 50%) of aberrant WT1 exon 2 splicing were detected for 11 tumors in the absence of a detectable WT1 DNA mutation. Also, alteration of normal WT1 alternative splicing, observed as RNA isoform loss, was detected in five tumors with no apparent WT1 genomic alteration, although no consistent pattern of RNA isoform loss was detected. This abnormal WT1 splicing, detected by either loss of exon 2 from some of the transcripts or loss of RNA isoforms, is statistically correlated with relapse (p = 0.005). These studies demonstrate that abnormal WT1 RNA processing is not a common mechanism of abrogating normal WT1 function in primary tumors. However, in those cases in which abnormal WTI splicing is present, these data indicate that it may serve as a useful prognostic marker for relapse in WT patients. ^

Adenosine mediated lung mast cell degranulation in the mouse

Adenosine has been implicated to play a role in inflammatory processes associated with asthma. Most notable is adenosine's ability to potentiate mediator release from mast cells. Mast cells are bone marrow derived inflammatory cells that can release mediators that have both immediate and chronic effects on airway constriction and inflammation. Most physiological roles of adenosine are mediated through adenosine receptors. Four subtypes of adenosine receptors have been identified, A1, A2A, A2B and A 3. The mechanisms by which adenosine can influence the release of mediators from lung tissue mast cells is not understood due to lack of in vivo models. Mice deficient in the enzyme adenosine deaminase (ADA) have been generated. ADA controls the levels of adenosine in tissues and cells, and consequently, adenosine accumulates in the lungs of ADA-deficient mice. ADA-deficient mice develop features seen in asthmatics, including lung eosinophilia and mucus hypersecretion. In addition, lung tissue mast cell degranulation was associated with elevated adenosine in ADA-deficient lungs and can be prevented by ADA enzyme therapy. We established primary murine lung mast cell cultures, and used real time RT-PCR and immunofluorescence to demonstrate that A 2A, A2B and A3 receptors are expressed on murine lung mast cells. Studies using selective adenosine receptor agonists and antagonists and A3 receptor deficient (A3−/−) mast cells suggested that activation of A3 receptors could induce mast cell mediator release in vitro. Furthermore, this mediator release was associated with increases in intracellular Ca++ that appeared to be mediated through a Gi and PI3K pathway. In addition, nebulized A3 receptor agonist directly induced lung mast cell degranulation in wild type mice while having no effect in A3−/− mice. These results demonstrate that the A3 receptor plays an important role in adenosine mediated murine lung mast cell degranulation. Therefore, the A3 adenosine receptor and its signaling pathways may represent novel therapeutic targets for the treatment and prevention of asthma. ^