Fucosylation of HLA-DRB1 regulates CD4+ T cell-mediated anti-melanoma immunity and enhances immunotherapy efficacy.

Immunotherapy efficacy is limited in melanoma, and combinations of immunotherapies with other modalities have yielded limited improvements but also adverse events requiring cessation of treatment. In addition to ineffective patient stratification, efficacy is impaired by paucity of intratumoral immune cells (itICs); thus, effective strategies to safely increase itICs are needed. We report that dietary administration of L-fucose induces fucosylation and cell surface enrichment of the major histocompatibility complex (MHC)-II protein HLA-DRB1 in melanoma cells, triggering CD4+ T cell-mediated increases in itICs and anti-tumor immunity, enhancing immune checkpoint blockade responses. Melanoma fucosylation and fucosylated HLA-DRB1 associate with intratumoral T cell abundance and anti-programmed cell death protein 1 (PD1) responder status in patient melanoma specimens, suggesting the potential use of melanoma fucosylation as a strategy for stratifying patients for immunotherapies. Our findings demonstrate that fucosylation is a key mediator of anti-tumor immunity and, importantly, suggest that L-fucose is a powerful agent for safely increasing itICs and immunotherapy efficacy in melanoma.

Analysis of MRE11 and Mortality Among Adults With Muscle-Invasive Bladder Cancer Managed With Trimodality Therapy.

Importance: Bladder-preserving trimodality therapy can be an effective alternative to radical cystectomy for treatment of muscle-invasive bladder cancer (MIBC), but biomarkers are needed to guide optimal patient selection. The DNA repair protein MRE11 is a candidate response biomarker that has not been validated in prospective cohorts using standardized measurement approaches. Objective: To evaluate MRE11 expression as a prognostic biomarker in MIBC patients receiving trimodality therapy using automated quantitative image analysis. Design, Setting, and Participants: This prognostic study analyzed patients with MIBC pooled from 6 prospective phase I/II, II, or III trials of trimodality therapy (Radiation Therapy Oncology Group [RTOG] 8802, 8903, 9506, 9706, 9906, and 0233) across 37 participating institutions in North America from 1988 to 2007. Eligible patients had nonmetastatic MIBC and were enrolled in 1 of the 6 trimodality therapy clinical trials. Analyses were completed August 2020. Exposures: Trimodality therapy with transurethral bladder tumor resection and cisplatin-based chemoradiation therapy. Main Outcomes and Measures: MRE11 expression and association with disease-specific (bladder cancer) mortality (DSM), defined as death from bladder cancer. Pretreatment tumor tissues were processed for immunofluorescence with anti-MRE11 antibody and analyzed using automated quantitative image analysis to calculate a normalized score for MRE11 based on nuclear-to-cytoplasmic (NC) signal ratio. Results: Of 465 patients from 6 trials, 168 patients had available tissue, of which 135 were analyzable for MRE11 expression (median age of 65 years [minimum-maximum, 34-90 years]; 111 [82.2%] men). Median (minimum-maximum) follow-up for alive patients was 5.0 (0.6-11.7) years. Median (Q1-Q3) MRE11 NC signal ratio was 2.41 (1.49-3.34). Patients with an MRE11 NC ratio above 1.49 (ie, above first quartile) had a significantly lower DSM (HR, 0.50; 95% CI, 0.26-0.93; P = .03). The 4-year DSM was 41.0% (95% CI, 23.2%-58.0%) for patients with an MRE11 NC signal ratio of 1.49 or lower vs 21.0% (95% CI, 13.4%-29.8%) for a ratio above 1.49. MRE11 NC signal ratio was not significantly associated with overall survival (HR, 0.84; 95% CI, 0.49-1.44). Conclusions and Relevance: Higher MRE11 NC signal ratios were associated with better DSM after trimodality therapy. Lower MRE11 NC signal ratios identified a poor prognosis subgroup that may benefit from intensification of therapy.

Utilizing digital pathology to quantify stromal caveolin-1 expression in malignant and benign ovarian tumors: Associations with clinicopathological parameters and clinical outcomes.

Loss of stromal caveolin-1 (Cav-1) is a biomarker of a cancer-associated fibroblast (CAF) phenotype and is related to progression, metastasis, and poor outcomes in several cancers. The objective of this study was to evaluate the clinical significance of Cav-1 expression in invasive epithelial ovarian cancer (OvCa). Epithelial and stromal Cav-1 expression were quantified in serous OvCa and benign ovarian tissue in two, independent cohorts-one quantified expression using immunohistochemistry (IHC) and the other using multiplex immunofluorescence (IF) with digital image analysis designed to target CAF-specific expression. Cav-1 expression was significantly downregulated in OvCa stroma compared to non-neoplastic stroma using both the IHC (p = 0.002) and IF (p = 1.8x10-13) assays. OvCa stroma showed Cav-1 downregulation compared to tumor epithelium with IHC (p = 1.2x10-24). Conversely, Cav-1 expression was higher in OvCa stroma compared to tumor epithelium with IF (p = 0.002). There was moderate correlation between IHC and IF methods for stromal Cav-1 expression (r2 = 0.69, p = 0.006) whereas there was no correlation for epithelial expression (r2 = 0.006, p = 0.98). Irrespective of the staining assay, neither response to therapy or overall survival correlated with the expression level of Cav-1 in the stroma or tumor epithelium. Our findings demonstrate a loss of stromal Cav-1 expression in ovarian serous carcinomas. Studies are needed to replicate these findings and explore therapeutic implications, particularly for immunotherapy response.

Role of Ki-67, MRE11, and PD-L1 as Predictive Biomarkers for Recurrence Pattern in Muscle-invasive Bladder Cancer.

BACKGROUND/AIM: Muscle invasive bladder cancer (MIBC) is an aggressive disease with high rates of local recurrence following radical cystectomy (RC). Currently, there are no clinically validated biomarkers to predict local only recurrence (LOR) and guide adjuvant treatment decisions. This pilot study evaluated the role of Ki-67, MRE11 and PD-L1 as predictive biomarkers for recurrence patterns in patients undergoing RC for MIBC. PATIENTS AND METHODS: Our institutional cystectomy database containing cases from 1992-2014 was queried for patients with local only recurrence (LOR), and case-matched to patients with distant recurrence (DR) and no recurrence (NR). Clinicopathological data were collected and a tissue microarray was analyzed for presence of Ki-67, MRE11, and PD-L1 using immunofluorescence and immunohistochemistry. RESULTS: Pathologic specimens from 42 patients (18 NR, 16 LOR, and 8 DR) were reviewed. Compared to normal bladder tissue, tumors had increased expression of Ki-67 (p<0.01) and PD-L1 (p<0.05). High Ki-67 was associated with recurrence pattern (local vs. distant) on univariate analysis (p<0.05). Ki-67 cell density varied by recurrence type: LOR (1354 cells/mm2), DR (557 cells/mm2) and NR (1111 cells/mm2) (p=0.034). CONCLUSION: Our selected biomarkers could distinguish MIBC from normal bladder tissue but could not classify samples by recurrence pattern.

Suppression of Reserve MCM Complexes Chemosensitizes to Gemcitabine and 5-Fluorouracil.

UNLABELLED: Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest forms of cancer and is very difficult to treat with conventional chemotherapeutic regimens. Gemcitabine and 5-fluorouracil are used in the management of PDAC and act by indirectly blocking replicative forks. However, these drugs are not highly effective at suppressing disease progression, indicating a need for the development of innovative therapeutic approaches. Recent studies indicate that suppression of the MCM helicase may provide a novel means to sensitize cancer cells to chemotherapeutic agents that inhibit replicative fork progression. Mammalian cells assemble more MCM complexes on DNA than are required to start S-phase. The excess MCM complexes function as backup initiation sites under conditions of replicative stress. The current study provides definitive evidence that cosuppression of the excess/backup MCM complexes sensitizes PDAC tumor lines to both gemcitabine and 5-FU, leading to increased loss of proliferative capacity compared with drugs alone. This occurs because reduced MCM levels prevent efficient recovery of DNA replication in tumor cells exposed to drug. PDAC tumor cells are more sensitive to MCM loss in the presence of gemcitabine than are nontumor, immortalized epithelial cells. Similarly, colon tumor cells are rendered less viable when cosuppression of MCM complexes occurs during exposure to the crosslinking agent oxaliplatin or topoisomerase inhibitor etoposide. IMPLICATIONS: These studies demonstrate that suppressing the backup complement of MCM complexes provides an effective sensitizing approach with the potential to increase the therapeutic index of drugs used in the clinical management of PDAC and other cancers.

A genome-wide investigation of microRNA expression identifies biologically-meaningful microRNAs that distinguish between high-risk and low-risk intraductal papillary mucinous neoplasms of the pancreas.

BACKGROUND: Intraductal papillary mucinous neoplasms (IPMNs) are pancreatic ductal adenocarcinoma (PDAC) precursors. Differentiating between high-risk IPMNs that warrant surgical resection and low-risk IPMNs that can be monitored is a significant clinical problem, and we sought to discover a panel of mi(cro)RNAs that accurately classify IPMN risk status. METHODOLOGY/PRINCIPAL FINDINGS: In a discovery phase, genome-wide miRNA expression profiling was performed on 28 surgically-resected, pathologically-confirmed IPMNs (19 high-risk, 9 low-risk) using Taqman MicroRNA Arrays. A validation phase was performed in 21 independent IPMNs (13 high-risk, 8 low-risk). We also explored associations between miRNA expression level and various clinical and pathological factors and examined genes and pathways regulated by the identified miRNAs by integrating data from bioinformatic analyses and microarray analysis of miRNA gene targets. Six miRNAs (miR-100, miR-99b, miR-99a, miR-342-3p, miR-126, miR-130a) were down-regulated in high-risk versus low-risk IPMNs and distinguished between groups (P<10-3, area underneath the curve (AUC) = 87%). The same trend was observed in the validation phase (AUC = 74%). Low miR-99b expression was associated with main pancreatic duct involvement (P = 0.021), and serum albumin levels were positively correlated with miR-99a (r = 0.52, P = 0.004) and miR-100 expression (r = 0.49, P = 0.008). Literature, validated miRNA:target gene interactions, and pathway enrichment analysis supported the candidate miRNAs as tumor suppressors and regulators of PDAC development. Microarray analysis revealed that oncogenic targets of miR-130a (ATG2B, MEOX2), miR-342-3p (DNMT1), and miR-126 (IRS-1) were up-regulated in high- versus low-risk IPMNs (P<0.10). CONCLUSIONS: This pilot study highlights miRNAs that may aid in preoperative risk stratification of IPMNs and provides novel insights into miRNA-mediated progression to pancreatic malignancy. The miRNAs identified here and in other recent investigations warrant evaluation in biofluids in a well-powered prospective cohort of individuals newly-diagnosed with IPMNs and other pancreatic cysts and those at increased genetic risk for these lesions.

MicroRNA-147 induces a mesenchymal-to-epithelial transition (MET) and reverses EGFR inhibitor resistance.

BACKGROUND: The epithelial-mesenchymal transition (EMT) is a key developmental program that is often activated during cancer progression and may promote resistance to therapy. An analysis of patients (n = 71) profiled with both gene expression and a global microRNA assessment (∼ 415 miRs) identified miR-147 as highly anti-correlated with an EMT gene expression signature score and postulated to reverse EMT (MET). METHODS AND FINDINGS: miR-147 was transfected into colon cancer cells (HCT116, SW480) as well as lung cancer cells (A-549). The cells were assessed for morphological changes, and evaluated for effects on invasion, motility, and the expression of key EMT markers. Resistance to chemotherapy was evaluated by treating cells with gefitinib, an EGFR inhibitor. The downstream genes regulated by miR-147 were assayed using the Affymetrix GeneChip U133 Plus2.0 platform. miR-147 was identified to: 1. cause MET primarily by increasing the expression of CDH1 and decreasing that of ZEB1; 2. inhibit the invasion and motility of cells; 3. cause G1 arrest by up-regulating p27 and down-regulating cyclin D1. miR-147 also dramatically reversed the native drug resistance of the colon cancer cell line HCT116 to gefitinib. miR-147 significantly repressed Akt phosphorylation, and knockdown of Akt with siRNA induced MET. The morphologic effects of miR-147 on cells appear to be attenuated by TGF-B1, promoting a plastic and reversible transition between MET and EMT. CONCLUSION: miR-147 induced cancer cells to undergo MET and induced cell cycle arrest, suggesting a potential tumor suppressor role. miR-147 strikingly increased the sensitivity to EGFR inhibitor, gefitinib in cell with native resistance. We conclude that miR-147 might have therapeutic potential given its ability to inhibit proliferation, induce MET, as well as reverse drug sensitivity.

Metabolic reprogramming of the immune response in the tumor microenvironment.

A Division of Cancer Biology, NCI sponsored workshop, Metabolic Reprogramming of the Immune Response in the Tumor Microenvironment, was held October 2nd in Bethesda, MD. The purpose of the workshop was to bring together cancer cell biologists and immunologists to explore the mechanistic relationships between the metabolic pathways used by cancer cells and anti-tumor immune cells and how this information could be used to improve cancer immunotherapy. At the conclusion of the workshop a general discussion focused on defining the major challenges and opportunities concerning the impact of metabolism on anti-tumor immunity and cancer immunotherapy as well as what tools, technologies, resources or community efforts are required to accelerate research in this area. Overall, future studies need to consider how cancer cell metabolic pathways differ from activated lymphocytes in order to define a therapeutic window for cancer therapy. Further, studies aimed at reprogramming the metabolic qualities of T cells with the goal of improving immunotherapy were considered a promising avenue.

Complementary strand microRNAs mediate acquisition of metastatic potential in colonic adenocarcinoma.

BACKGROUND: Altered expression of specific microRNAs (miRNA) is known to occur during colorectal carcinogenesis. However, little is known about the genome-wide alterations in miRNA expression during the neoplastic progression of primary colorectal cancers. METHODS: Using a miRNA array platform, we evaluated the expression of 668 miRNA in primary colonic adenocarcinomas. Biological functions of selected miRNA were evaluated with in vitro invasion assays. RESULTS: RNA was extracted for miRNA analysis from 65 primary colon cancers. We identified a seven-miRNA expression signature that differentiated stage I and stage IV primary colon cancers. We then demonstrated this signature was able to discriminate between stage II and III primary colon cancers. Six differentially expressed miRNA were downregulated in association with the development of metastases, and all 7 miRNA were complementary strand miRNA. We transfected HCT-116, a highly invasive colon cancer cell line, with corresponding downregulated miRNA and demonstrated that overexpression of three miRNA (miR200c*, miR143*, and miR424*) significantly abrogated invasive potential. CONCLUSION: We have identified a seven-miRNA signature that is associated with metastatic potential in the primary tumor. Forced overexpression of three downregulated miRNA resulted in attenuation of in vitro invasion, suggesting direct tumor suppressive function and further supporting the biological importance of complementary strand miRNA.

Novel molecular markers of malignancy in histologically normal and benign breast.

To detect the molecular changes of malignancy in histologically normal breast (HNB) tissues, we recently developed a novel 117-gene-malignancy-signature. Here we report validation of our leading malignancy-risk-genes, topoisomerase-2-alpha (TOP2A), minichromosome-maintenance-protein-2 (MCM2) and "budding-uninhibited-by-benzimidazoles-1-homolog-beta" (BUB1B) at the protein level. Using our 117-gene malignancy-signature, we classified 18 fresh-frozen HNB tissues from 18 adult female breast cancer patients into HNB-tissues with low-grade (HNB-LGMA; N = 9) and high-grade molecular abnormality (HNB-HGMA; N = 9). Archival sections of additional HNB tissues from these patients, and invasive ductal carcinoma (IDC) tissues from six other patients were immunostained for these biomarkers. TOP2A/MCM2 expression was assessed as staining index (%) and BUB1B expression as H-scores (0-300). Increasing TOP2A, MCM2, and BUB1B protein expression from HNB-LGMA to HNB-HGMA tissues to IDCs validated our microarray-based molecular classification of HNB tissues by immunohistochemistry. We also demonstrated an increasing expression of TOP2A protein on an independent test set of HNB/benign/reductionmammoplasties, atypical-ductal-hyperplasia with and without synchronous breast cancer, DCIS and IDC tissues using a custom tissue microarray (TMA). In conclusion, TOP2A, MCM2, and BUB1B proteins are potential molecular biomarkers of malignancy in histologically normal and benign breast tissues. Larger-scale clinical validation studies are needed to further evaluate the clinical utility of these molecular biomarkers.

Proliferative genes dominate malignancy-risk gene signature in histologically-normal breast tissue.

Historical data have indicated the potential for the histologically-normal breast to harbor pre-malignant changes at the molecular level. We postulated that a histologically-normal tissue with "tumor-like" gene expression pattern might harbor substantial risk for future cancer development. Genes associated with these high-risk tissues were considered to be "malignancy-risk genes". From a total of 90 breast cancer patients, we collected a set of 143 histologically-normal breast tissues derived from patients harboring breast cancer who underwent curative mastectomy, as well as a set of 42 invasive ductal carcinomas (IDC) of various histologic grades. All samples were assessed for global gene expression differences using microarray analysis. For the purpose of this study we defined normal breast tissue to include histologically normal and benign lesions. Here we report the discovery of a "malignancy-risk" gene signature that may portend risk of breast cancer development in benign, but molecularly-abnormal, breast tissue. Pathway analysis showed that the malignancy-risk signature had a dramatic enrichment for genes with proliferative function, but appears to be independent of ER, PR, and HER2 status. The signature was validated by RT-PCR, with a high correlation (Pearson correlation = 0.95 with P < 0.0001) with microarray data. These results suggest a predictive role for the malignancy-risk signature in normal breast tissue. Proliferative biology dominates the earliest stages of tumor development.

Catalyzing community action within a national campaign: VERB community and national partnerships.

The VERB campaign used a social marketing approach to deliver its message through the mass media, school and community promotions, and partnerships to encourage children aged 9-13 years (tweens) to be physically active every day. This paper presents the VERB campaign's community and national partnership strategy, highlights three successful partnerships, and discusses challenges associated with the efforts. The national advertising generated awareness of and affinity for the product's brand and motivated the primary audience to seek out the product. The campaign's national and community partners were engaged to facilitate a product-distribution channel. The campaign developed a three-pronged partnership strategy to integrate the promotion with the placement of the campaign's product (physical activity): (1) reframe the way physical activity is positioned and delivered; (2) connect the brand to the point-of-purchase; and (3) refer (or drive) the audience to the action outlets, opportunities, places, spaces and programs to purchase the product. The VERB campaign provided partners with marketing training and resources to assist them as they leveraged tweens' brand awareness and supported regular physical activity among tweens. The method of technical assistance and the types of marketing tools were provided in relationship to four characteristics of the partner: (1) partner's network, (2) leaders and champions in the network, (3) partner's financial resources for community campaigns; and (4) partner's understanding of the marketing mindset. Coordinated, collaborative, and strong mass-media and community-based interventions within a national social marketing campaign can sustain the immediate effects of such campaigns.

Insig2 is associated with colon tumorigenesis and inhibits Bax-mediated apoptosis.

Insulin-induced gene 2 (Insig2) was recently identified as a putative positive prognostic biomarker for colon cancer prognosis. Insig2 has been previously reported to be an endoplasmic reticulum (ER) membrane protein, and a negative regulator of cholesterol synthesis. Here we report that Insig2 was validated as a gene with univariate negative prognostic capacity to discriminate human colon cancer survivorship. To investigate the functional roles it plays in tumor development and malignancy, Insig2 was over-expressed in colon cancer cells resulting in increased cellular proliferation, invasion, anchorage independent growth and inhibition of apoptosis. Over-expression of Insig2 appeared to suppress chemotherapeutic drug treatment-induced Bcl2 associated X protein (Bax) expression and activation. Insig2 was also found to localize to the mitochondria/heavy membrane fraction and associate with conformationally changed Bax. Moreover, Insig2 altered the expression of several additional apoptosis genes located in mitochondria, further supporting its new functional role in regulating mitochondrial mediated apoptosis. Our findings show that Insig2 is a novel colon cancer biomarker, and suggest, for the first time, a reasonable connection between Insig2 and Bax-mediated apoptosis through the mitochondrial pathway.

Green tea catechins suppress the DNA synthesis marker MCM7 in the TRAMP model of prostate cancer.

Green tea catechins (GTCs) exert chemopreventive effects in many cancer models. Several studies implicate the DNA synthesis marker minichromosome maintenance protein 7 (MCM7) in prostate cancer progression, growth and invasion; representing a novel therapeutic target. In this study, we investigated the effect of GTCs on MCM7 expression in the transgenic adenocarcinoma mouse prostate model (TRAMP). DNA microarray, immunohistochemistry and western blot analysis showed that GTCs significantly suppressed MCM7 in the TRAMP mice treated with GTCs. Our study indicates that the cellular DNA replication factor MCM7 is involved in prostate cancer (CaP) and MCM7 gene expression was reduced by GTCs. Together, these results suggest a possible role of GTCs in CaP chemoprevention in which MCM7 plays a critical role.

Prediction of radiation sensitivity using a gene expression classifier.

The development of a successful radiation sensitivity predictive assay has been a major goal of radiation biology for several decades. We have developed a radiation classifier that predicts the inherent radiosensitivity of tumor cell lines as measured by survival fraction at 2 Gy (SF2), based on gene expression profiles obtained from the literature. Our classifier correctly predicts the SF2 value in 22 of 35 cell lines from the National Cancer Institute panel of 60, a result significantly different from chance (P = 0.0002). In our approach, we treat radiation sensitivity as a continuous variable, significance analysis of microarrays is used for gene selection, and a multivariate linear regression model is used for radiosensitivity prediction. The gene selection step identified three novel genes (RbAp48, RGS19, and R5PIA) of which expression values are correlated with radiation sensitivity. Gene expression was confirmed by quantitative real-time PCR. To biologically validate our classifier, we transfected RbAp48 into three cancer cell lines (HS-578T, MALME-3M, and MDA-MB-231). RbAp48 overexpression induced radiosensitization (1.5- to 2-fold) when compared with mock-transfected cell lines. Furthermore, we show that HS-578T-RbAp48 overexpressors have a higher proportion of cells in G2-M (27% versus 5%), the radiosensitive phase of the cell cycle. Finally, RbAp48 overexpression is correlated with dephosphorylation of Akt, suggesting that RbAp48 may be exerting its effect by antagonizing the Ras pathway. The implications of our findings are significant. We establish that radiation sensitivity can be predicted based on gene expression profiles and we introduce a genomic approach to the identification of novel molecular markers of radiation sensitivity.

Osteopontin induces multiple changes in gene expression that reflect the six "hallmarks of cancer" in a model of breast cancer progression.

Tumor progression is a multistep process, which enables cells to evolve from benign to malignant tumors. This progression has been suggested to depend on six essential characteristics identified as the "hallmarks of cancer," which include: self-sufficiency in growth signals, insensitivity to growth-inhibitory signals, evasion of apoptosis, limitless replicative potential, sustained angiogenesis, and tissue invasion and metastasis. Osteopontin (OPN) is an integrin-binding protein that has been shown to be associated with the progression of several cancer types, and to play an important functional role in various aspects of malignancy, particularly tissue invasion and metastasis. Here we studied genes regulated by OPN in a model of human breast cancer using oligonucleotide microarray technology by comparing the gene-expression profiles of 21NT mammary carcinoma cells transfected to overexpress OPN versus mock-transfected control cells. From over 12,000 human genes, we identified 99 known human genes differentially regulated by OPN whose expression changed by at least 1.5-fold and showed statistically significant differences in mean expression levels between groups. Functional classification of these genes into the hallmarks of cancer categories showed that OPN can affect the expression of genes involved in all six categories in this model. Furthermore, we were able to validate the expression of 18/19 selected candidate genes by quantitative real-time PCR, further supporting our microarray findings. This study provides the first evidence that OPN can lead to numerous gene expression changes that influence multiple aspects of tumor progression and malignant growth.

A GM-CSF/CD40L producing cell augments anti-tumor T cell responses.

BACKGROUND: Tumors evade T cell-mediated rejection despite the presence of tumor associated antigens (TAAs) and T cells specific for these TAAs in cancer patients. Therapeutic tumor vaccines are being developed to prevent this evasion. Previous reports revealed that anti-tumor T cell responses could be activated in mice when granulocyte macrophage-colony stimulating factor (GM-CSF) or CD40L are produced at tumor vaccine sites. We sought to test the hypothesis that production of GM-CSF and CD40L by a bystander cell line could induce an anti-tumor T cell response in an in vitro human model. MATERIALS AND METHODS: The K562 cell line was stably transfected with the human GM-CSF and CD40L genes. The effect of this cell line on T cell responses was tested in a human autologous mixed tumor cell/lymph node cell model using tissue from a series of cancer patients. RESULTS: There was no significant anti-tumor T cell response when human lymphocytes derived from tumor-draining lymph nodes were stimulated with autologous tumor cells in vitro. However, significant anti-tumor T cell responses were observed when bystander cells transfected with CD40L and GM-CSF were added to the cultures. CONCLUSIONS: A fully autologous human model consisting of tumor cells as stimulator cells and tumor-draining lymph nodes as responder cells can be used to test immunotherapeutic strategies. T cells in these lymph nodes are unresponsive to autologous tumor cells, but this lack of responsiveness can be reversed in the presence of GM-CSF and CD40L. These data provide a rationale for testing tumor cell vaccines incorporating GM-CSF- and CD40L-expressing bystanders in clinical trials.

Oncogene regulation of tumor suppressor genes in tumorigenesis.

We attempted to demonstrate whether there is an epigenetic link between oncogenes and tumor suppression genes in tumorigenesis. We designed a high throughput model to identify a candidate group of tumor suppressor genes potentially regulated by oncogenes. Gene expression profiling of mock-transfected versus v-src-transfected 3Y1 rat fibroblasts identified significant overexpression of DNA methyltransferase 1, the enzyme responsible for aberrant genome methylation, in v-src-transfected fibroblasts. Secondary microarray analyses identified a number of candidate tumor suppressor genes that were down-regulated by v-src but were also re-expressed following treatment with 5-aza-2'-deoxycytidine, a potent demethylating agent. This candidate group included both tumor suppressor genes that are known to be silenced by DNA hypermethylation and those that have not been previously identified with promoter hypermethylation. To further validate our model, we identified tsg, a tumor suppressor gene that was shown to be down-regulated by v-src and found to harbor dense promoter hypermethylation. Our model demonstrates a cooperative relationship between oncogenes and tumor suppressor genes mediated through promoter hypermethylation.

Clusterin-mediated apoptosis is regulated by adenomatous polyposis coli and is p21 dependent but p53 independent.

Clusterin is a widely expressed glycoprotein that has been paradoxically observed to have both pro- and antiapoptotic functions. Recent reports suggest this apparent dichotomy of function may be related to two different isoforms, one secreted and cytoplasmic, the other nuclear. To clarify the functional role of clusterin in regulating apoptosis, we examined its expression in human colon cancer tissues and in human colon cancer cell lines. We additionally explored its expression and activity using models of adenomatous polyposis coli (APC)- and chemotherapy-induced apoptosis. Clusterin RNA and protein levels were decreased in colon cancer tissues largely devoid of wild-type APC when compared with matched normal tissue controls, suggesting a means for invasive cancers to avoid apoptosis. Conversely, induction of apoptosis by expression of wild-type APC or by treatment with chemotherapy led to increased clusterin RNA and protein levels localizing to apoptotic nuclei. We found that transient transfection of clusterin to colon cancer cell lines directly enhanced basal and chemotherapy-induced apoptosis. Clusterin-induced apoptosis was inhibited by antisense clusterin and was found to be highly dependent on p21 but not p53 expression, yet a deficit in p21 can be subverted by clusterin transfection. Collectively, these data support the hypothesis that nuclear clusterin function is proapoptotic when induced by APC or chemotherapy in the context of p21 expression. Absent of p21, clusterin in not induced, and apoptosis is significantly inhibited. These data support a potential therapeutic role for clusterin in enhancing chemotherapy-induced apoptosis and in promoting apoptosis in cells deficient in p21.

Autocrine activation by interleukin 1alpha induces the fibrogenic phenotype of systemic sclerosis fibroblasts.

OBJECTIVE: To explore the cellular localization of interleukin 1alpha (IL-1alpha) in cultured fibroblasts from lesional skin of patients with systemic sclerosis (SSc) and to study the role of intracellular IL-1alpha in the activation of fibroblasts. METHODS: Dermal fibroblasts were derived from 12 patients with SSc. Expression of IL-1alpha mRNA was examined using reverse transcriptase-polymerase chain reaction (RT-PCR). The cellular distribution of IL-1alpha was examined by subcellular fractionation, flow cytometry, and immunocytochemistry. A full-length IL-1alpha cDNA was subcloned into the pcDNA3 vector to create sense and antisense-encoding constructs. Normal and SSc fibroblasts were stably transfected with the sense and antisense-encoding constructs, respectively. Stably transfected fibroblast clones were analyzed for the production of procollagen and IL-6 protein by ELISA, alpha1(I) procollagen mRNA by Northern blot hybridization, and proliferation by [3H]thymidine incorporation. RESULTS: SSc-affected fibroblasts constitutively expressed intracellular IL-1alpha, which was predominantly located in the nucleus. Inhibition of IL-1alpha expression in SSc-affected fibroblasts using antisense constructs resulted in decreased proliferation, IL-6 production, and procollagen synthesis. Conversely, overexpression of IL-1alpha in normal fibroblasts resulted in development of the SSc fibroblast phenotype. CONCLUSION: IL-1alpha is an important autocrine fibrogenic factor in SSc, suggesting that inhibition of intracellular IL-1alpha may be a novel strategy for the treatment of SSc.