A pleiotropy scan to discover new susceptibility loci for pancreatic ductal adenocarcinoma

Pleiotropic variants (i.e., genetic polymorphisms influencing more than one phenotype) are often associated with cancer risk. A scan of pleiotropic variants was successfully conducted ten years ago in relation to pancreatic ductal adenocarcinoma susceptibility. However, in the last decade, genetic association studies performed on several human traits have greatly increased the number of known pleiotropic variants. Based on the hypothesis that variants already associated with a least one trait have a higher probability of association with other traits, 61,052 variants reported to be associated by at least one genome wide association study (GWAS) with at least one human trait were tested in the present study consisting of two phases (discovery and validation), comprising a total of 16,055 pancreatic ductal adenocarcinoma (PDAC) cases and 212,149 controls. The meta-analysis of the two phases showed two loci (10q21.1-rs4948550 (P=6.52×10-5) and 7q36.3-rs288762 (P=3.03×10-5) potentially associated with PDAC risk. 10q21.1-rs4948550 shows a high degree of pleiotropy and it is also associated with colorectal cancer risk while 7q36.3-rs288762 is situated 28,558 base pairs upstream of the Sonic Hedgehog (SHH) gene, which is involved in the cell differentiation process and PDAC etiopathogenesis. In conclusion, none of the single nucleotide polymorphisms (SNPs) showed a formally statistically significant association after correction for multiple testing. However, given their pleiotropic nature and association with various human traits including colorectal cancer, the two SNPs showing the best associations with PDAC risk merit further investigation through fine mapping and ad hoc functional studies.

Gender-related differences in patients with carcinoid syndrome: new insights from an Italian multicenter cohort study

BACKGROUND

The incidence of neuroendocrine neoplasm (NEN) and related carcinoid syndrome (CaS) has increased markedly in recent decades, and women appear to be more at risk than men. As per other tumors, gender may be relevant in influencing the clinical and prognostic characteristics of NEN-associated CS. However, specific data on carcinoid syndrome (CaS) are still lacking.

PURPOSE

To evaluate gender differences in clinical presentation and outcome of CaS.

METHODS

Retrospective analysis of 144 CaS patients from 20 Italian high-volume centers was conducted. Clinical presentation, tumor characteristics, therapies, and outcomes (progression-free survival, PFS, overall survival, OS) were correlated to gender.

RESULTS

Ninety (62.5%) CaS patients were male. There was no gender difference in the site of primary tumor, tumor grade and clinical stage, as well as in treatments. Men were more frequently smokers (37.2%) and alcohol drinkers (17.8%) than women (9.5%, p = 0.002, and 3.7%, p = 0.004, respectively). Concerning clinical presentation, women showed higher median number of symptoms (p = 0.0007), more frequent abdominal pain, tachycardia, and psychiatric disorders than men (53.3% vs 70.4%, p = 0.044; 6.7% vs 31.5%, p = 0.001; 50.9% vs. 26.7%, p = 0.003, respectively). Lymph node metastases at diagnosis were more frequent in men than in women (80% vs 64.8%; p = 0.04), but no differences in terms of PFS (p = 0.51) and OS (p = 0.64) were found between gender.

CONCLUSIONS

In this Italian cohort, CaS was slightly more frequent in males than females. Gender-related differences emerged in the clinical presentation of CaS, as well as gender-specific risk factors for CaS development. A gender-driven clinical management of these patients should be advisable.

Pathologic tumor response to neoadjuvant therapy in resected pancreatic cancer: does it affect prognosis?

Neoadjuvant therapy (NAT) + surgical resection for pancreatic cancer (PC) has gained consensus in recent years. Pathological response (PR) is generally assessed according to the College of American Pathologists grading system, ranging from 0 (complete response) to 3 (no response). The aim of our study is to evaluate the PR in a series of resections for PC after NAT and its prognostic implication. 112 patients undergone NAT and resection for PC between 2011 and 2020 were retrospectively evaluated. PR was 0/1, 2 and 3 in 18 (15%), 79 (61%) and 29 (24%) cases, respectively. Chemotherapy regimens different from FOLFIRINOX and gemcitabine + nab-paclitaxel (OR 11.61 (2.53-53.36), p = 0.002) and lymphovascular invasion (OR 11.28 (1.89-67.23), p = 0.008) were associated to PR-3. Median follow-up was 25.8 (3.6-130.5) months. For PR-0/1, PR-2 and PR-3, median DFS was 45.8, 11.5, 4.6 months (p < 0.0001), respectively, while median OS was not reached, 27.1 and 17.5 months (p = 0.0006), respectively. At univariate analysis, PR-0/1 was significantly associated to better DFS and OS (HR 0.33 (0.17-0.67), p = 0.002; HR 0.20 (0.07-0.54), p = 0.002, respectively). At multivariate analysis, pancreaticoduodenectomy (HR 0.50 (0.30-0.84), p = 0.009), LNR (HR 27.14 (1.21-608.9), p = 0.038) and lymphovascular invasion (HR 1.99 (1.06-3.76), p = 0.033) were independently associated to DFS; pre-treatment CA 19.9 value (HR 1.00 (1.00-1.00), p = 0.025), post-treatment resectability status (HR 0.51 (0.28-0.95), p = 0.035), pancreaticoduodenectomy (HR 0.56 (0.32-0.99), p = 0.050), severe morbidity (2.99 (1.22-7.55), p = 0.017), LNR (HR 56.8 (2.08-1548.3), p = 0.017), lymphovascular invasion (HR 2.18 (1.08-4.37), p = 0.029) were independently associated to OS. PR did not reach statistical significance at multivariate analysis. A favorable PR is observed only in a limited number of cases. The prognostic role of PR, despite being promising, remains unclear and further multicentric studies are needed.

Radical Resection in Entero-Pancreatic Neuroendocrine Tumors: Recurrence-Free Survival Rate and Definition of a Risk Score for Recurrence

BACKGROUND

Surgery with radical intent is the only potentially curative option for entero-pancreatic neuroendocrine tumors (EP-NETs) but many patients develop recurrence even after many years. The subset of patients at high risk of disease recurrence has not been clearly defined to date.

OBJECTIVE

The aim of this retrospective study was to define, in a series of completely resected EP-NETs, the recurrence-free survival (RFS) rate and a risk score for disease recurrence.

PATIENTS AND METHODS

This was a multicenter retrospective analysis of sporadic pancreatic NETs (PanNETs) or small intestine NETs (SiNETs) [G1/G2] that underwent R0/R1 surgery (years 2000-2016) with at least a 24-month follow-up. Survival analysis was performed using the Kaplan-Meier method and risk factor analysis was performed using the Cox regression model.

RESULTS

Overall, 441 patients (224 PanNETs and 217 SiNETs) were included, with a median Ki67 of 2% in tumor tissue and 8.2% stage IV disease. Median RFS was 101 months (5-year rate 67.9%). The derived prognostic score defined by multivariable analysis included prognostic parameters, such as TNM stage, lymph node ratio, margin status, and grading. The score distinguished three risk categories with a significantly different RFS (p < 0.01).

CONCLUSIONS

Approximately 30% of patients with EP-NETs recurred within 5 years after radical surgery. Risk factors for recurrence were disease stage, lymph node ratio, margin status, and grading. The definition of risk categories may help in selecting patients who might benefit from adjuvant treatments and more intensive follow-up programs.

Risk of preoperative understaging of duodenal neuroendocrine neoplasms: a plea for caution in the treatment strategy

PURPOSE

Pretreatment staging is the milestone for planning either surgical or endoscopic treatment in duodenal neuroendocrine neoplasms (dNENs). Herein, a series of surgically treated dNEN patients was evaluated to assess the concordance between the pre- and postsurgical staging.

METHODS

Retrospective analysis of patients with a histologically confirmed diagnosis of dNENs, who underwent surgical resection observed at eight Italian tertiary referral centers. The presurgical TNM stage, based on the radiological and functional imaging, was compared with the pathological TNM stage, after surgery.

RESULTS

From 2000 to 2019, 109 patients were included. Sixty-six patients had G1, 26 a G2, 7 a G3 dNEN (Ki-67 not available in 10 patients). In 46/109 patients (42%) there was disagreement between the pre- and postsurgical staging, being it understaged in 42 patients (38%), overstaged in 4 (3%). As regards understaging, in 25 patients (22.9%), metastatic loco-regional nodes (N) resulted undetected at both radiological and functional imaging. Understaging due to the presence of distal micrometastases (M) was observed in 2 cases (1.8%). Underestimation of tumor extent (T) was observed in 12 patients (11%); in three cases the tumor was understaged both in T and N extent.

CONCLUSIONS

Conventional imaging has a poor detection rate for loco-regional nodes and micrometastases in the presurgical setting of the dNENs. These results represent important advice when local conservative approaches, such as endoscopy or local surgical excision are considered and it represents a strong recommendation to include endoscopic ultrasound in the preoperative tools for a more accurate local staging.

Long-term outcomes after pancreatoduodenectomy for ampullary cancer: The influence of the histological subtypes and comparison with the other periampullary neoplasms

BACKGROUND

Ampullary carcinoma (AC) is histologically classified as intestinal (In-AC), pancreaticobiliary (Pb-AC) or mixed-AC. The prognostic role of AC subtypes has been debated and remains unclear. The aims of this study were to evaluate outcomes after pancreatoduodenectomy (PD) for each subtype of AC and to compare these with pancreatic ductal adenocarcinoma [PDAC] and distal cholangiocarcinoma [DCC].

METHODS

PDs performed for AC between 2010 and 2018 were retrospectively evaluated. Histological subtype was obtained for all patients. One-year, 3-year and 5-year disease-free-survival (DFS) and overall survival (OS) rates were calculated. Kaplan-Meier survival analysis was performed to compare Pb-AC, In-AC and mixed-AC. Comparison with PDs performed for PDAC and DCC during the same period was also performed.

RESULTS

A total of 97 patients undergoing PD for AC were evaluated: 34 (35.1%) In-AC, 54 (55.7%) Pb-AC and 9 mixed-AC (9.3%). DFS and OS rates for Pb-AC were significantly lower compared to In-AC (p < 0.05 and p < 0.01), but similar to mixed-AC (p = 0.3 and p = 0.4). Adjuvant therapy was not associated with increased survival, regardless of the histological subtype (p > 0.05). During the same period, 337 and 53 PDs for PDAC and DCC, respectively, were performed. In-AC was associated with significantly better outcomes compared to PDAC and DCC (p < 0.001); DFS and OS rates for Pb-AC and mixed AC were significantly higher compared to PDAC (p < 0.001), but similar to DCC (p > 0.05).

CONCLUSIONS

Pb-AC has significantly worse survival compared to In-AC. Moreover, mixed-AC should be considered as Pb-AC. Pb-AC and mixed-AC seem to have better prognosis compared to PDAC, but similar to DCC.

External validation of three nomograms predicting survival using an international cohort of patients with resected pancreatic head ductal adenocarcinoma

Objective

Lymph node ratio (LNR, positive lymph nodes/collected lymph nodes during surgery) was identified as an important prognostic factor of survival in resected pancreatic cancer. Several nomograms based on LNR were recently proposed to predict survival after pancreatoduodenectomy (PD). The present study aimed to externally validate 3 published nomograms using an international cohort.

Methods

Consecutive patients with ductal adenocarcinoma of the pancreatic head who underwent PD without neoadjuvant treatment from 6 tertiary centers in Europe and the USA were retrospectively collected from 2000 to 2017. Patients with metastases at diagnosis, R2 resection, missing data regarding LNR, and who died within 90 postoperative days were excluded. The 3 selected nomograms were the updated Amsterdam nomogram (including LNR, adjuvant therapy, margin status, and tumor grade), the nomogram by Pu et al. (including LNR, age, tumor grade, and T stage) and the nomogram by Li et al. (including LNR, age, tumor location, grade, size, and TNM stage). Overall survivals (OS) were calculated using Kaplan-Meier method. For the validation, calibration (Hosmer-Lemeshow test), discrimination capacity (ROC curves for 3-year OS), and clinical utility (sensitivity and specificity at the value of Youden index) were assessed.

Results

After exclusion of 95 patients with metastases, R2 resection, and who died within 90 postoperative days, 1167 patients were included. Median OS of the entire cohort was 23 months (95% confidence interval: 21-24).

For the 3 nomograms, Kaplan-Meier curves showed significant diminution of OS with increasing scores (p &lt; 0.01 for the 3 nomograms). All nomograms showed good calibration (non significant Hosmer-Lemeshow goodness-of-fit tests). For the updated Amsterdam nomogram, the area under the ROC curve (AUROC) for 3-year OS was 0.66. Sensitivity and specificity were 73% and 50%. Regarding the nomogram by Pu et al., the AUROC was 0.67. Sensitivity and specificity were 65% and 60%. For the nomogram by Li et al., the AUROC was 0.67, while sensitivity and specificity were 56% and 71%.

Conclusion

The 3 selected nomograms were validated using an external international cohort and displayed interesting and comparable predictive values. Those nomograms may be used in clinical practice to estimate survival after PD for ductal adenocarcinoma.

Immune infiltrating cells in duodenal cancers

Background

Duodenal adenocarcinoma (DA) is a rare yet aggressive malignancy, with increasing incidence in the last decades. Its low frequency has hampered a thorough understanding of the pathogenesis of the disease and of its biology, limiting the identification of tailored therapeutic options. A large body of evidence has clearly shown the clinical relevance of immune cells in solid tumors, correlating immune features with post-surgical prognosis. The aim of this study was to analyze the immune contexture in a cohort of duodenal adenocarcinomas surgically resected at our Institution and define its correlation with clinical variables.

Methods

Tissue slides from paraffin-embedded tumor specimens of 15 consecutive DA and 3 adenomas that underwent a pancreaticoduodenectomy in our center between 2010 to 2018 were immunohistochemically stained. The density (percentage of immune reactive area, IRA%) of immune markers CD45RO, CD8, CD20, IL-17, PD-1, CD68 was quantified by computer-assisted image analysis. Demographic, clinical, histopathological data were collected.

Results

In our population, median IRA % (IQR) of immune subsets was respectively CD45RO-TILs 2.19 (2.14), CD8-TIL 0.42 (0.81), CD20-TILs 0.22 (0.51), CD20-TLT 2.84 (4.64), CD68-TAM 2.19 (1.56), IL17⁺ cells 0.39 (0.39), PD1-TILs 0.19 (0.41). The median follow-up was 47.5 (22.4–63.3) months. At statistical analysis, the density of CD8-TILs inversely correlated with lymph node ratio (p = 0.013), number of metastatic lymph nodes (p = 0.019), and was lower in N+ adenocarcinomas compared to N0 (1.07 vs 0.29; p = 0.093), albeit not significantly. Stratifying patients for the N status, the density of CD8-TILs decreased with the increasing of the N stage (p = 0.065) and was lower in patients who experienced recurrence and died for the disease (0.276 vs 0.641; p = 0.044). Notably, also CD68-TAM distribution was different in patients who had recurrence versus patients who did not (1.028 vs 2.276; p = 0.036).

Conclusions

Immune cells showed variable expression in correlation with common prognostic factors, suggesting T cell infiltration may play a protective role towards lymphatic spread of disease and nodal metastatization. Furthermore, T cell density and macrophage infiltration were associated to a lower risk of recurrence and disease related death. A multicentric approach may be indicated to allow analysis of larger cohorts of patients, potentially increasing the power of our observations.

ZNF521 Has an Inhibitory Effect on the Adipogenic Differentiation of Human Adipose-Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are multipotent progenitors present in the bone marrow stroma and in subcutaneous abdominal fat, an abundant and easily accessible source of MSCs with the ability to differentiate along multiple lineage pathways. The stem cell-associated transcription co-factor Zinc Finger Protein 521 (ZNF521/zfp521) has been implicated in the control of the homeostasis of hematopoietic, neural and osteo-adipogenic progenitors. Here we document through the analysis of a panel of human adipose-derived stem cells (hADSCs), that ZNF521 strongly inhibits the generation of mature adipocytes. Enforced overexpression of ZNF521 in these cells resulted in a significant delay and reduction in adipocyte differentiation upon exposure to inducers of adipogenesis. Of particular relevance, ZNF521 was able to inhibit the expression of ZNF423, recently identified as an essential commitment factor necessary for the generation of pre-adipocytes. Conversely, silencing of ZNF521 was found to significantly enhance the adipogenic differentiation of hADSCs. Inhibition of adipogenesis by ZNF521 was at least in part due to inhibition of EBF1. Taken together, these results confirm a role for ZNF521 as a key negative regulator of adipocyte differentiation of hADSCs.

Inhibition of the glucocorticoid receptor results in an enhanced miR-99a/100-mediated radiation response in stem-like cells from human prostate cancers

Radiation therapy is a major primary treatment option for both localized early stage prostate cancer, and for advanced, regionally un-resectable, cancer. However, around 30% of patients still experience biochemical recurrence after radiation therapy within 10 years. Thus, identification of better biomarkers and new targets are urgently required to improve current therapeutic strategies. The miR-99 family has been shown to play an important role in the regulation of the DNA damage response, via targeting of the SWI/SNF chromatin remodeling factors, SMARCA5 and SMARCD1 in cell line models. In the present study, we have demonstrated that low expression of miR-99a and miR-100 is present in cell populations which are relatively radiation insensitive, for example in prostate cancer stem cells and in castration-resistant prostate cancer. Additionally, treatment of cells with the synthetic glucocorticoid, Dexamethasone resulted in decreased miR-99a and 100 expression, suggesting a new mechanism of miR-99a and 100 regulation in androgen-independent prostate cells. Strikingly, treatment of prostate cells with the glucocorticoid receptor inhibitor, Mifepristone was found to sensitize prostate cells to radiation by increasing the levels of miR-99a and miR-100. These results qualify the miR99 family as markers of radiation sensitivity and as potential therapeutic targets to improve efficiency of radiotherapy.

Abstract 1900: Understanding the biological role of latexin in the normal and malignant prostate

The retinoid-inducible protein Latexin (LXN) acts as a stem cell suppressor in normal murine hematopoiesis, and in human tumors where it can influence both tumor cell migration and invasion (Liang et al, Nature genetics 2007). We have shown that LXN is silenced in the stem cell fraction of primary prostate epithelial cells, and that expression increases as cells differentiate through the prostate basal epithelial hierarchy towards mature luminal cells. Furthermore, transient knockdown of LXN significantly increased clonogenic potential and promoted a more invasive phenotype in primary prostate epithelia (Oldridge et al, Oncogenesis 2013). LXN may therefore be involved in the differentiation of prostate epithelial cells, but could act as a tumor suppressor in Prostate Cancer (CaP), in addition to other tumours. In genome databases LXN is described as an inhibitor for Carboxypeptidase A4, but despite considerable molecular characterisation, the mechanism of action has remained an enigma since perhaps paradoxically LXN appears to be able to function independently of its classical CPA4 inhibitory role. To resolve this, we adopted an unbiased approach to determine if targeted re-expression of LXN or its binding partners could provide a viable novel drug target for the treatment of CaP. Our preliminary studies had revealed that LXN was an exclusively cytosolic protein in prostate epithelial cells. However, subsequent live cell imaging of primary prostate epithelial cells overexpressing YFP-LXN demonstrated for the first time that, whilst predominantly cytosolic, LXN was also present within the cell nucleus. To characterise the effects of LXN overexpression on gene transcription after LXN-expressing lentiviral transduction of primary prostate epithelial cells, we utilised Affymetrix HTA2 gene arrays. Perhaps surprisingly, short-term overexpression of LXN did not significantly effect global gene transcription compared to controls (n=4 P=NS). Additionally, we used IP/MS to investigate the potential interacting partners of LXN, using multiple approaches, including both overexpression of HA-tagged and WT LXN, and endogenous LXN as bait. These approaches failed to reveal any strong (and reproducible) intracellular protein interactors of LXN. From these data, we hypothesised that LXN may function as a secreted protein. We found that LXN was present in not only the conditioned media of LXN+ prostate epithelial cells, but also preliminary evidence that LXN is enriched in extracellular exosomes. Therefore, LXN may perform its biological roles extracellularly, or at the cell surface. Our current work is focusing on determining the functional consequences of secreted LXN on prostate epithelia and to establish potential protein: protein interactions of LXN in the extracellular space. Full characterisation of LXN function considering its potent biological effects on cancer cells will determine its suitability as a therapeutic in CaP and other cancers.

Citation Format: Robert I. Seed, Alberto J. Taurozzi, Giovanna Nappo, Holger H. Erb, Anne Collins, Norman J. Maitland, Fiona Frame. Understanding the biological role of latexin in the normal and malignant prostate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1900. doi:10.1158/1538-7445.AM2017-1900

Rate of convergence to equilibrium of marked Hawkes processes

In this article we obtain rates of convergence to equilibrium of marked Hawkes processes in two situations. Firstly, the stationary process is the empty process, in which case we speak of the rate of extinction. Secondly, the stationary process is the unique stationary and nontrivial marked Hawkes process, in which case we speak of the rate of installation. The first situation models small epidemics, whereas the results in the second case are useful in deriving stopping rules for simulation algorithms of Hawkes processes with random marks.

Minimally Invasive Pancreatic Resection: Is It Really the Future?

The introduction and widespread application of minimally invasive surgery has been one of the most important innovations that radically changed the practice of surgery during the last few decades. The application to pancreatic surgery of minimally invasive approach has only recently emerged: both laparoscopic distal pancreatectomy (LDP) and laparoscopic pancreaticoduodenectomy (LPD) can be competently performed. LDP and LPD are advocated to improved perioperative outcomes, including decreased blood loss, shorter length of stay, reduced postoperative pain and expedited time to functional recovery. However, the indication to minimally invasive approach for pancreatic surgery is often benign or low-grade malignant pathologies. In this review, we summarize the current data on minimally invasive pancreatic surgery, focusing on indication, perioperative and oncological outcomes.

hERG1 channels drive tumour malignancy and may serve as prognostic factor in pancreatic ductal adenocarcinoma

Background:

hERG1 channels are aberrantly expressed in human cancers. The expression, functional role and clinical significance of hERG1 channels in pancreatic ductal adenocarcinoma (PDAC) is lacking.

Methods:

hERG1 expression was tested in PDAC primary samples assembled as tissue microarray by immunohistochemistry using an anti-hERG1 monoclonal antibody (α-hERG1-MoAb). The functional role of hERG1 was studied in PDAC cell lines and primary cultures. ERG1 expression during PDAC progression was studied in Pdx-1-Cre,LSL-Kras^G12D/+,LSL-Trp53^R175H/+ transgenic (KPC) mice. ERG1 expression in vivo was determined by optical imaging using Alexa-680-labelled α-hERG1-MoAb.

Results:

(i) hERG1 was expressed at high levels in 59% of primary PDAC; (ii) hERG1 blockade decreased PDAC cell growth and migration; (iii) hERG1 was physically and functionally linked to the Epidermal Growth Factor-Receptor pathway; (iv) in transgenic mice, ERG1 was expressed in PanIN lesions, reaching high expression levels in PDAC; (v) PDAC patients whose primary tumour showed high hERG1 expression had a worse prognosis; (vi) the α-hERG1-MoAb could detect PDAC in vivo.

Conclusions:

hERG1 regulates PDAC malignancy and its expression, once validated in a larger cohort also comprising of late-stage, non-surgically resected cases, may be exploited for diagnostic and prognostic purposes in PDAC either ex vivo or in vivo.

UMG Lenti: novel lentiviral vectors for efficient transgene- and reporter gene expression in human early hematopoietic progenitors

Lentiviral vectors are widely used to investigate the biological properties of regulatory proteins and/or of leukaemia-associated oncogenes by stably enforcing their expression in hematopoietic stem and progenitor cells. In these studies it is critical to be able to monitor and/or sort the infected cells, typically via fluorescent proteins encoded by the modified viral genome. The most popular strategy to ensure co-expression of transgene and reporter gene is to insert between these cDNAs an IRES element, thus generating bi-cistronic mRNAs whose transcription is driven by a single promoter. However, while the product of the gene located upstream of the IRES is generally abundantly expressed, the translation of the downstream cDNA (typically encoding the reporter protein) is often inconsistent, which hinders the detection and the isolation of transduced cells. To overcome these limitations, we developed novel lentiviral dual-promoter vectors (named UMG-LV5 and –LV6) where transgene expression is driven by the potent UBC promoter and that of the reporter protein, EGFP, by the minimal regulatory element of the WASP gene. These vectors, harboring two distinct transgenes, were tested in a variety of human haematopoietic cell lines as well as in primary human CD34⁺ cells in comparison with the FUIGW vector that contains the expression cassette UBC-transgene-IRES-EGFP. In these experiments both UMG-LV5 and UMG–LV6 yielded moderately lower transgene expression than FUIGW, but dramatically higher levels of EGFP, thereby allowing the easy distinction between transduced and non-transduced cells. An additional construct was produced, in which the cDNA encoding the reporter protein is upstream, and the transgene downstream of the IRES sequence. This vector, named UMG-LV11, proved able to promote abundant expression of both transgene product and EGFP in all cells tested. The UMG-LVs represent therefore useful vectors for gene transfer-based studies in hematopoietic stem and progenitor cells, as well as in non-hematopoietic cells.

Synergy between enzastaurin doxorubicin in inducing melanoma apoptosis

Melanoma is resistant to most standard chemotherapeutics. We analysed the combined effect of doxorubicin and enzastaurin on cell death of four melanoma cell lines, namely G361, SK-MEL3, A375 and SAN. Enzastaurin IC50 was calculated by measure of growth inhibition with MTS assay and corresponded to 2 μM; the half maximal cytotoxicity of doxorubicin was obtained at 3 μM dose. Evaluation of combination index showed synergism (CI > 1) or additive effect (CI = 1) with all melanoma cell lines, with enzastaurin doses ≥0.6 μM and doxorubicin doses ≥1 μM. Combination of the two drugs resulted in increase in caspase 3 and 8 activation, in comparison with activation by single agents. Caspase 8 activation was impaired by TNFR-1 blocking. Our results show doxorubicin-stimulated production of TNFα, whereas enzastaurin-stimulated TNFR-1 expression on plasma membrane. The effect on TNFR-1 appeared to be mediated by PKCζ inhibition. Taken together, our findings suggest that enzastaurin increases doxorubicin-induced apoptosis of melanoma by a mechanism involving, at least in part, activation of the TNF-α signal.

Abstract 755: FK506 binding protein 51 (FKBP51) binds to p300 and acts as transcriptional co-regulator of ABCG2 gene expression in melanoma

Several lines of evidence support a role for FKBPs in chromatin modifications and cancer. Particularly for some of them, DNA association and regulation of gene expression has been demonstrated, mediated by histone- or transcription factor- chaperone activity. FKBP51 is an immunophilin that functions also as co chaperone of several proteins and receptors. We previously found this molecule has an essential role in melanoma resistance to the therapy and aggressiveness. Melanoma cells expressing stem cell markers (MCSC) produced high levels of FKBP51. In addition, the number of MCSC (identified by ABCG2 expression) was increased in FKBP51 over expressing melanoma cell lines. By converse, reduced expression of cancer stemness genes was measured in FKBP51 silenced melanoma. Since ABCG2+ cells also contained high levels of the general transcriptional co-activator, namely E1A binding protein p300, we hypotesized that FKBP51 might act as a p300 co chaperone with a role in transcriptional regulation of stemness markers. By co-IP assays, we show that FKBP51 interacts with p300 and partecipates in transcriptional complexes with Smad 2 and p300. By chromatin immunoprecipitation assays (ChIP) we demonstrate that FKBP51 binds to chromatin. We used different couples of primers to amplify different regions of the ABCG2 promoter, in FKBP51-immunoprecipitated chromatin and found enrichment of DNA fragments corresponding to a first sequence localized at 3450 bp (-3450) from the transcription start site (TSS), a second at -3219, and a third at -939. Differently, no enrichment in closest regions was found, suggesting the specificity of FKBP51 binding to ABCG2 promoter. In addition, we found p300 bound to the same regions of ABCG2 promoter, and such binding was impaired by FKBP51 downmodulation, suggesting the immunophilin regulatated the binding of p300 to DNA. In conclusion, our study supports the conclusion that FKBP51 partecipates in the transcriptional apparatus that controls expression of melanoma stemness genes, acting as co chaperone of p300.

Citation Format: Simona Romano, Giovanna Nappo, Elena Cesaro, Antonio Candela, Maria Fiammetta Romano. FK506 binding protein 51 (FKBP51) binds to p300 and acts as transcriptional co-regulator of ABCG2 gene expression in melanoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 755. doi:10.1158/1538-7445.AM2013-755

Abstract 260: FK506 binding protein (FKBP) 51 controls “TNF-related apoptosis inducing ligand” (TRAIL) response in melanoma

FKBP51 is a cochaperone that regulates several biological processes in the cell, through protein-protein interaction. Very recently, we have found that FKBP51 is hyperexpressed in malignant melanoma and plays a crucial role in its chemo- and radio-resistance. Downmodulation of FKBP51, by gene silencing, produces an increase of melanoma apoptosis induced by several cytotoxic stimuli. To investigate the mechanism of the increased apoptosis sensitivity of FKBP51-silenced melanoma, we performed a study of protein expression profiles in melanoma cells that were depleted or not of FKBP51, using ionizing radiation (IR) as apoptotic stimulus. Among the multiple signaling pathways that were found modulated in FKBP51-silenced cells, a marked upregulation of TRAIL receptors was found. In particular, the death receptors were significantly increased in FKBP51-depleted cells, while the decoy receptors, that do not transduce death signal, were decreased in the same cells. Among TRAIL receptors, TRAIL R2 (DR5) transduces most efficiently the death signal. Aim of the present study was to validate the increase of DR5 at mRNA and protein level in FKBP51-silenced melanoma cells and investigate the effect of FKBP51 silencing on TRAIL-induced apoptosis. Summary of key findings FKBP51-silencing increased DR5 transcript by 6,1 folds (range 2,8/14,7 folds), in melanoma cells, measured by Real-time PCR. Flow cytometry confirmed the increased expression of DR5 (by more than 100%) in FKBP51 silenced cells, compared with non silenced melanoma cells. The study of apoptosis was in accordance with the expression of death receptors. Indeed, FKBP51 silencing increased TRAIL-induced apoptosis, as suggested by both propidium iodide incorporation and annexin V staining of melanoma cells. Low levels of apoptosis were measured in melanoma cells stimulated with 100ng/ml TRAIL (18 + 6%). By contrast, 39 + 14% of apoptosis was measured in FKBP51-depleted melanoma cells, following TRAIL stimulation (P= 0.01). FKBP51 regulated the acetylation pattern of melanoma as suggested by the reduced amount af acetylated protein in FKBP51 silenced-melanoma cells (D), most interestingly, reduced levels of acetylated Yin Yang 1 transcription factor (YY1) involved in control of DR5 tanscription, were found in FKBP51-silenced melanoma, as suggested by western blot assay. Conclusions FKBP51 gene silencing produces a marked increase in TRAIL sensitivity of melanoma, due to upregulation of TRAIL death receptors. FKBP51 decreases the acetylation pattern of melanoma, and in particular of the DR5 transcriptional repressor YY1, suggesting that epigenetic modification of DNA could be responsible for reduced TRAIL-receptor transcription and resistance to apoptosis of melanoma.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 260. doi:1538-7445.AM2012-260

The emerging role of large immunophilin FK506 binding protein 51 in cancer

FK506 binding protein 51 (FKBP51) is an immunophilin physiologically expressed in lymphocytes. Very recently, aberrant expression of this protein was found in melanoma; FKBP51 expression correlates with melanoma aggressiveness and is maximal in metastatic lesions. FKBP51 promotes NF-κB activation and is involved in the resistance to genotoxic agents, including anthracyclines and ionizing radiation. FKBP51 is a cochaperone with peptidyl-prolyl isomerase activity that regulates several biological processes through protein-protein interaction. There is increasing evidence that FKBP51 hyperexpression is associated with cancer and this protein has a relevant role in sustaining cell growth, malignancy, and resistance to therapy. There is also evidence that FKBP ligands are potent anticancer agents, in addition to their immunosuppressant activity. In particular, rapamycin and its analogs have shown antitumor activity across a variety of human cancers in clinical trials. Although, classically, rapamycin actions are ascribed to inhibition of mTOR, recent studies indicate FKBP51 is also an important molecular determinant of the drug's anticancer activity. The aim of this article is to review the functions of FKBP51, especially in view of the recent findings that this protein is a potential oncogene when deregulated and a candidate target for signaling therapies against cancer.

Differential effect of atorvastatin and tacrolimus on proliferation of vascular smooth muscle and endothelial cells

Although considered promising for use in drug-eluting stents (DES), tacrolimus failed clinically. Tacrolimus inhibits growth factor production but can also act as a growth factor on vascular smooth muscle cells (VSMC). This unexpected proliferative stimulus could reverse the beneficial effects of the drug on restenosis. We hypothesized that tacrolimus' association with statins, which lower cholesterol and impair cell proliferation, could restore tacrolimus' beneficial effect by abrogating the aberrant proliferative stimulus. Additionally, since maintenance of endothelial function represents a challenge for new-generation DES, we investigated the combined effect of tacrolimus and atorvastatin on endothelial cells. Human VSMC and umbilical vein endothelial cells (HUVEC) were incubated with 100 nM tacrolimus and increasing doses of atorvastatin (0-3.0 μM). Atorvastatin plus tacrolimus dose-dependently inhibited VSMC proliferation. The percentage of cells incorporating 5-bromo-2'-deoxyuridine (BrdU) in their DNA was 49 ± 14% under basal conditions, 62 ± 15% (P = 0.01) with tacrolimus, 40 ± 22% with 3 μM atorvastatin, and 30 ± 7% (P < 0.05) with 3 μM atorvastatin plus tacrolimus. Atorvastatin downregulated β-catenin, Erk1 and Erk2, and cyclin B in tacrolimus-stimulated VSMC. In contrast, atorvastatin plus tacrolimus did not affect proliferation of endothelial cells. The percentage of HUVEC incorporating BrdU in their DNA was 47 ± 8% under basal conditions, 58 ± 6% (P = 0.01) with tacrolimus, 45 ± 4% with 3 μM atorvastatin, and 49 ± 1% with 3 μM atorvastatin plus tacrolimus. Both agents stimulated endoglin production by HUVEC. Taken together, these results suggest that, when combined with tacrolimus, atorvastatin exerts a dose-dependent antiproliferative effect on VSMC. In contrast, atorvastatin acts in concert with tacrolimus in HUVEC to stimulate production of endoglin, a factor that has an important role in endothelial repair. Our study supports the conclusion that prevention of postcoronary in-stent restenosis and late thrombosis may benefit of concomitant association of tacrolimus and high doses of atorvastatin.