Significant associations of mismatch repair gene polymorphisms with clinical outcome of pancreatic cancer

Intratumoral TREX1 Induction Promotes Immune Evasion by Limiting Type I IFN

Chromosomal instability is a hallmark of human cancer that is associated with aggressive disease characteristics. Chromosome mis-segregations help fuel natural selection, but they risk provoking a cGAS-STING immune response through the accumulation of cytosolic DNA. The mechanisms of how tumors benefit from chromosomal instability while mitigating associated risks, such as enhanced immune surveillance, are poorly understood. Here, we identify cGAS-STING-dependent upregulation of the nuclease TREX1 as an adaptive, negative feedback mechanism that promotes immune evasion through digestion of cytosolic DNA. TREX1 loss diminishes tumor growth, prolongs survival of host animals, increases tumor immune infiltration, and potentiates response to immune checkpoint blockade selectively in tumors capable of mounting a type I IFN response downstream of STING. Together, these data demonstrate that TREX1 induction shields chromosomally unstable tumors from immune surveillance by dampening type I IFN production and suggest that TREX1 inhibitors might be used to selectively target tumors that have retained the inherent ability to mount an IFN response downstream of STING. See related article by Lim et al., p. 663.

Structural, functional analysis and association of MSH6 rs1800932, rs1042821 polymorphisms with clinical outcome in North Indian lung cancer patients treated with platinum-based doublet chemotherapy

BACKGROUND

In this study, we have done structural and functional analysis of rs1800932 rs1042821 polymorphisms and tried to estimate any association of these polymorphisms with clinical outcomes in north Indian lung cancer patients.

METHODS

Genotyping of 500 lung cancer patients was completed utilizing PCR-RFLP (Polymerase chain reaction- Restriction fragment length polymorphism). MedCalc statistical software was used to calculate adjusted and unadjusted odds ratios. Various computational tools like SIFT PROVEAN are used for functional analysis. Structural analysis was completed via MODELLER and CHIMERA.

RESULTS

In our study, patients suffering from small cell lung cancer (SCLC) and harboring heterozygous genotype (AG) for MSH6 (rs1800932) polymorphism have reported a significant increase in median survival time (MST) (20.6 vs. 7.6 months, p = 0.03). Furthermore, for MSH6 rs1042821 polymorphism, patients undergoing docetaxel and carbo/cisplatin combination chemotherapeutic regimen and carrying heterogeneous genotype (CT) reported a significant increase in MST (16.6 vs.8.36 months, p = 0.03) and a corresponding decrease in hazard ratio 0.42 (95% CI= 0.18-1.03). Structural and Functional analysis of rs1042821 polymorphism revealed that it is present in the non-coding region of MSH6 protein and is significantly associated with increased overall survival.

CONCLUSIONS

These results suggest that MSH6 rs1800932 rs1042821 polymorphisms are involved in increasing the overall survival of lung cancer patients, further confirmed by computational analysis.

New insights on familial colorectal cancer type X syndrome

Familial colorectal cancer type X (FCCTX) is a heterogeneous colorectal cancer predisposition syndrome that, although displays a cancer pattern similar to Lynch syndrome, is mismatch repair proficient and does not exhibit microsatellite instability. Besides, its genetic etiology remains to be elucidated. In this study we performed germline exome sequencing of 39 cancer-affected patients from 34 families at risk for FCCTX. Variant classification followed the American College of Medical Genetics and Genomics (ACMG) guidelines. Pathogenic/likely pathogenic variants were identified in 17.65% of the families. Rare and potentially pathogenic alterations were identified in known hereditary cancer genes (CHEK2), in putative FCCTX candidate genes (OGG1 and FAN1) and in other cancer-related genes such as ATR, ASXL1, PARK2, SLX4 and TREX1. This study provides novel important clues that can contribute to the understanding of FCCTX genetic basis.

Carboplatin activates the cGAS-STING pathway by upregulating the TREX-1 (three prime repair exonuclease 1) expression in human melanoma

Human melanoma is a highly aggressive type of cancer, causing significant mortalities despite the advances in treatment. Carboplatin is a cisplatin analog necessary for the treatment of various cancers and can also be used to treat human melanoma. We assessed the effects and mechanisms leading to inhibited proliferation and induced apoptosis of human melanoma after carboplatin therapy in vitro and in vivo. TREX1, cGAS/STING, and apoptotic protein expressions were determined through RT-qPCR and western blot assays. Cell proliferation was validated through MTT assays. The study used SK-MEL-1 and SK-HEP-1 tumor cell line inoculations along with carboplatin in nude mice to validate the results. The TREX1 levels were down-regulated in human melanoma cell lines. TREX1 overexpression-induced apoptosis and decreased proliferation in the human melanoma cell lines. TREX1 overexpression also activated the cGAS/STING pathway to induce apoptosis and decrease cell growth. Carboplatin activated TREX1, induced apoptosis, and decreased proliferation in the human melanoma cancerous cell lines. Finally, carboplatin reduced the in-vivo tumor size and weight. In conclusion, the study revealed that carboplatin activated TREX1 and cGAS/STING pathways to upregulate apoptosis. The work also provides in vitro and in vivo evidence to understand the effects of TREX overexpression on tumor suppression. Targeting of TREX1/cGAS/STING pathway could be an effective therapeutic alternative to human melanoma.

TREX1 as a Novel Immunotherapeutic Target

Mutations in the TREX1 3' → 5' exonuclease are associated with a spectrum of autoimmune disease phenotypes in humans and mice. Failure to degrade DNA activates the cGAS-STING DNA-sensing pathway signaling a type-I interferon (IFN) response that ultimately drives immune system activation. TREX1 and the cGAS-STING DNA-sensing pathway have also been implicated in the tumor microenvironment, where TREX1 is proposed to degrade tumor-derived DNA that would otherwise activate cGAS-STING. If tumor-derived DNA were not degraded, the cGAS-STING pathway would be activated to promote IFN-dependent antitumor immunity. Thus, we hypothesize TREX1 exonuclease inhibition as a novel immunotherapeutic strategy. We present data demonstrating antitumor immunity in the TREX1 D18N mouse model and discuss theory surrounding the best strategy for TREX1 inhibition. Potential complications of TREX1 inhibition as a therapeutic strategy are also discussed.

A Novel DNA Replication-Related Signature Predicting Recurrence After R0 Resection of Pancreatic Ductal Adenocarcinoma: Prognostic Value and Clinical Implications

The aim of any surgical resection for pancreatic ductal adenocarcinoma (PDAC) is to achieve tumor-free margins (R0). R0 margins give rise to better outcomes than do positive margins (R1). Nevertheless, postoperative morbidity after R0 resection remains high and prognostic gene signature predicting recurrence risk of patients in this subgroup is blank. Our study aimed to develop a DNA replication-related gene signature to stratify the R0-treated PDAC patients with various recurrence risks. We conducted Cox regression analysis and the LASSO algorithm on 273 DNA replication-related genes and eventually constructed a 7-gene signature. The predictive capability and clinical feasibility of this risk model were assessed in both training and external validation sets. Pathway enrichment analysis showed that the signature was closely related to cell cycle, DNA replication, and DNA repair. These findings may shed light on the identification of novel biomarkers and therapeutic targets for PDAC.

Clinicopathological and survival characteristic of mismatch repair status in ovarian clear cell carcinoma

BACKGROUND AND OBJECTIVES

We sought to explore the expression of mismatch repair (MMR) status and its correlation with clinicopathologic and survival characteristics in ovarian clear cell carcinoma (OCCC).

METHODS

Expression of four MMR proteins (MLH1, PMS, MSH2, and MSH6) were measured using tissue microarray-based immunohistochemistry in 120 OCCC patients. The associations of clinicopathologic parameters with recurrence-free survival (RFS) and overall survival (OS) were analyzed by the Kaplan-Meier method, and multivariate analysis was further performed by the Cox regression model.

RESULTS

Overall, 120 OCCC patients met the entry criteria, and their MMR status was detected, consisting of 24 patients with dMMR and 96 patients with proficient MMR (pMMR). Patients with dMMR were strongly associated with platinum-sensitive disease (P = .006) and large tumor volume (P = .038). Among all the patients who have received surgery, tumors with dMMR had a better RFS and OS than those with pMMR (hazard ratio [HR] for recurrence: 0.459 [95% confidence interval {95% CI} = 0.224-0.940], P = .029; HR for death: 0.381 [95% CI = 0.170-0.853], P = .015). In subgroup analysis, dMMR patients experienced a better trend of RFS (HR = 0.273; P = .055) and OS (HR = 0.165; P = .040) than pMMR cases among early stages (I-II), but this difference was not observed in advanced stage (III-IV) patients. Meanwhile, pMMR was associated with a more favorable trend of prognosis than dMMR in platinum-resistant patients (RFS: HR = 0.317, P = .051; OS: HR = 0.370, P = .046). Multivariate analysis revealed that only advanced stages (III-IV) were adverse independent prognosticators for both RFS (HR = 5.938 [95% CI = 2.804-12.574]; P < .001) and OS (HR = 6.209 [95% CI = 2.724-14.156]; P < .001).

CONCLUSION

Tumors with dMMR were related to better OS in OCCC on univariate analysis. Only the tumor stage was an independent prognosticator for both RFS and OS. MMR status is a potentially valuable prognostic index in OCCC patients, and larger prospective studies are required to validate its prognostic role.

Somatic mutations in the DNA repairome in prostate cancers in African Americans and Caucasians

Most hereditary tumors show aberrations in DNA repair genes or their regulators. In contrast, only a minority of sporadic tumors show alterations in these genes. As a result, genomic instability is currently considered an enhancer of tumorigenesis rather than an obligatory event in this process. However, tumor heterogeneity presents a significant technical challenge for most cancer genomics studies performed at less than 100× mean resolution depth. To address the importance of genomic instability in prostate carcinogenesis and tumor progression, we performed ultrahigh depth exome sequencing of 124 DNA damage repair/response (repairome) genes in 63 tumors and matched normal tissue samples in African Americans and Caucasians. The average sequence depth was 712-fold for DNA isolated from normal tissue and 368-fold for FFPE tumors. We identified 671 somatic mutations in tumors from African Americans and 762 somatic mutations in tumors in Caucasians. The most frequently mutated DNA repairome genes were EXO1, ATR, POLQ, NEIL3, ERCC6, BRCA2, BRCA1, XPC, JAG1, RPA1, POLE, ATM, and LIG1 in African American men, and POLQ, NEIL3, POLB, BRCA2, EXO1, ERCC6, ATR, RBBP8, BRCA1, ATM, JAG1, XPC, and POLE in Caucasians. We found that 89% of tumors had at least one mutation in nucleotide excision repair pathway genes in African Americans, whereas >40% of tumors had mutations in base excision repair pathway genes in Caucasians. We further identified a marginal increase in mutation rate in tumors in African Americans with increasing age. Tumors in Caucasians did not show a correlation with age, but a progressive increase in the mutation rate was observed at higher Gleason scores. Our data reveal significant differences in the molecular signatures in the DNA repairome in prostate cancer between African Americans and Caucasians. These data also have substantial implications regarding the well-known health disparities in prostate cancer, such as the higher mortality in African Americans than Caucasians.

Aspartate β-hydroxylase promotes pancreatic ductal adenocarcinoma metastasis through activation of SRC signaling pathway

BACKGROUND

Signaling pathways critical for embryonic development re-emerge in adult pancreas during tumorigenesis. Aspartate β-hydroxylase (ASPH) drives embryonic cell motility/invasion in pancreatic development/differentiation. We explored if dysregulated ASPH is critically involved in pancreatic cancer pathogenesis.

METHODS

To demonstrate if/how ASPH mediates malignant phenotypes, proliferation, migration, 2-D/3-D invasion, pancreatosphere formation, immunofluorescence, Western blot, co-immunoprecipitation, invadopodia formation/maturation/function, qRT-PCR, immunohistochemistry (IHC), and self-developed in vitro metastasis assays were performed. Patient-derived xenograft (PDX) models of human pancreatic ductal adenocarcinoma (PDAC) were established to illustrate in vivo antitumor effects of the third-generation small molecule inhibitor specifically against ASPH's β-hydroxylase activity. Prognostic values of ASPH network components were evaluated with Kaplan-Meier plots, log-rank tests, and Cox proportional hazards regression models.

RESULTS

ASPH renders pancreatic cancer cells more aggressive phenotypes characterized by epithelial-mesenchymal transition (EMT), 2-D/3-D invasion, invadopodia formation/function as demonstrated by extracellular matrix (ECM) degradation, stemness (cancer stem cell marker upregulation and pancreatosphere formation), transendothelial migration (mimicking intravasation/extravasation), and sphere formation (mimicking metastatic colonization/outgrowth at distant sites). Mechanistically, ASPH activates SRC cascade through direct physical interaction with ADAM12/ADAM15 independent of FAK. The ASPH-SRC axis enables invadopodia construction and initiates MMP-mediated ECM degradation/remodeling as executors for invasiveness. Pharmacologic inhibition of invadopodia attenuates in vitro metastasis. ASPH fosters primary tumor development and pulmonary metastasis in PDX models of PDAC, which is blocked by a leading compound specifically against ASPH enzymatic activity. ASPH is silenced in normal pancreas, progressively upregulated from pre-malignant lesions to invasive/advanced stages of PDAC. Expression profiling of ASPH-SRC network components independently/jointly predicts clinical outcome of PDAC patients. Compared to a negative-low level, a moderate-very high level of ASPH, ADAM12, activated SRC, and MMPs correlated with curtailed overall survival (OS) of pancreatic cancer patients (log-rank test, ps < 0.001). The more unfavorable molecules patients carry, the more deleterious prognosis is destinated. Patients with 0-2 (n = 4), 3-5 (n = 8), 6-8 (n = 24), and 9-12 (n = 73) unfavorable expression scores of the 5 molecules had median survival time of 55.4, 15.9, 9.7, and 5.0 months, respectively (p < 0.001).

CONCLUSION

Targeting the ASPH-SRC axis, which is essential for propagating multi-step PDAC metastasis, may specifically/substantially retard development/progression and thus improve prognosis of PDAC.

A polymorphism within the mismatch repair gene predicts prognosis and adjuvant chemotherapy benefit in gastric cancer

BACKGROUND

Defective mismatch repair (dMMR) and microsatellite instability (MSI) correlate with gastric cancer (GC) outcome. We hypothesized that MMR genetic polymorphisms that have low-penetrant effects but may cause heterogeneous MMR capability among individuals also affect GC outcome.

METHODS

The polymorphisms rs1800734 in MLH1, rs2303428 and rs3732183 in MSH2, rs735943 in EXO1, and rs11797 in TREX1 were selected and analyzed in independent discovery and validation sets that included 167 and 593 patients, respectively. MSI was determined.

RESULTS

In both the discovery and validation sets, the rs2303428 TC + CC genotype correlated with poor overall survival (OS) in non-cardia (P < 0.05) but not in cardia GC. Multivariate models showed that for OS of patients with non-cardia GC, the rs2303428 TC + CC genotype was an independent predictor in the validation set (HR 1.54; 95% CI 1.02-2.32; P = 0.040) and had a trend to be an independent predictor in the discovery set (HR 1.70; 95% CI 0.96-3.01; P = 0.067). Furthermore, in both patient sets, fluoropyrimidines-based adjuvant chemotherapy improved OS for non-cardia patients with the rs2303428 TC + CC genotype (HR 0.14; 95% CI 0.04-0.57; P = 0.006; and HR 0.29; 95% CI 0.15-0.58; P < 0.001, respectively) but not for those with the TT genotype. The rs2303428 genotypes were not associated with MSI frequency. The rs2303428 TC + CC genotype correlated with reduced expressions for thymidylate synthetase, P-glycoprotein and ERCC1 (P < 0.05) in non-cardia GC.

CONCLUSIONS

The rs2303428 genotypes may predict prognosis and adjuvant chemotherapy benefit in non-cardia GC patients.

Circulating Biomarkers for Prediction of Objective Response to Chemotherapy in Pancreatic Cancer Patients

Pancreatic cancer is a lethal disease with increasing incidence. Most patients present with advanced disease, for which palliative systemic chemotherapy is the only therapeutic option. Despite improved median survival rates with FOLFIRINOX or gemcitabine chemotherapy compared to the best supportive care, many individual patients may not benefit from chemotherapy. Biomarkers are needed to predict who will benefit from chemotherapy and to monitor a patient’s response to chemotherapy. This review summarizes current research and future perspectives on circulating biomarkers for systemic chemotherapy response.

Polymorphisms in DNA mismatch repair pathway genes predict toxicity and response to cisplatin chemoradiation in head and neck squamous cell carcinoma patients

Head and neck squamous cell carcinoma (HNSCC) is treated with cisplatin (CDDP) and radiotherapy (RT), and distinct results are observed among patients with similar clinicopathological aspects. This prospective study aimed to investigate whether MLH1 c.-93G>A (rs1800734), MSH2 c.211+9C>G (rs2303426), MSH3 c.3133G>A (rs26279), EXO1 c.1765G>A (rs1047840), and EXO1 c.2270C>T (rs9350) single nucleotide polymorphisms (SNPs) of the mismatch repair (MMR) pathway change side effects and response rate of 90 HNSCC patients treated with CDDP and RT. DNA from peripheral blood was analyzed by PCR-based methods to obtain genotypes. It was observed 4.27-fold and 4.69-fold increased risks of presenting pronounced nephrotoxicity with treatment in patients with MSH3 GG and EXO1 rs9350 CC genotypes compared with patients with GA or AA and CT or TT genotypes, respectively. MSH3 GG or GA and GT haplotype of EXO1 rs1047840 and rs9350 SNPs conferred to patients 10.29 and 4.00 more chances of presenting pronounced ototoxicity after treatment than MSH3 AA genotype and other EXO1 haplotypes, respectively. Patients with EXO1 rs1047840 GA or AA genotype and AC haplotype of EXO1 rs1047840 and rs9350 SNPs had both 9.55-fold increased risks of achieving partial response or stable disease instead of complete remission after treatment than patients with EXO1 GG genotype and other EXO1 haplotypes, respectively. For the first time, our data show preliminary indication that inherited alterations of DNA MMR pathway, related to MSH3 rs26279, EXO1 rs1047840 and EXO1 rs9350 SNPs, modify toxicity and response to chemoradiation in HNSCC, and may contribute to future personalized treatment of patients.

Significant association of the EXO1 rs851797 polymorphism with clinical outcome of ovarian cancer

BACKGROUND

Exonuclease 1 (EXO1), one of DNA mismatch repair pathway genes, functions in maintaining genomic stability and affects tumor progression. We hypothesized that genetic variations in EXO1 may predict clinical outcomes in epithelial ovarian cancer (EOC).

METHODS

In this cohort study with 1,030 consecutive EOC patients, we genotyped four potentially functional polymorphisms in EXO1 by the Taqman assay and evaluated their associations with patients' survival.

RESULTS

Using multivariate Cox proportional hazards regression models, we found that rs851797AG/GG genotypes were significantly associated with recurrence and cancer death (HR =1.30 and 1.38, 95% CI =1.11-1.52 and 1.02-1.88, respectively). Kaplan-Meier survival estimates showed that patients who carried rs851797AG/GG genotypes had poorer progression-free survival and poorer overall survival, compared with rs851797AA genotype carriers (log-rank test, P=0.002 and 0.025, respectively). Moreover, patients with older age at menophania, advanced stage tumor, or being received incomplete cytoreduction were more likely to be recurrent and dead.

CONCLUSION

EXO1 rs851797 polymorphism can predict the clinical outcomes in EOC patients. In addition, age at menophania, FIGO stage, and complete cytoreduction might be independently prognostic factors of ovarian cancer. Large studies with functional experiments are warranted to validate these findings.

Genomic Variations in Pancreatic Cancer and Potential Opportunities for Development of New Approaches for Diagnosis and Treatment

Human pancreatic cancer has a very poor prognosis with an overall five-year survival rate of less than 5% and an average median survival time of six months. This is largely due to metastatic disease, which is already present in the majority of patients when diagnosed. Although our understanding of the molecular events underlying multi-step carcinogenesis in pancreatic cancer has steadily increased, translation into more effective therapeutic approaches has been inefficient in recent decades. Therefore, it is imperative that novel and targeted approaches are designed to facilitate the early detection and treatment of pancreatic cancer. Presently, there are numerous ongoing studies investigating the types of genomic variations in pancreatic cancer and their impact on tumor initiation and growth, as well as prognosis. This has led to the development of therapeutics to target these genetic variations for clinical benefit. Thus far, there have been minimal clinical successes directly targeting these genomic alterations; however research is ongoing to ultimately discover an innovative approach to tackle this devastating disease. This review will discuss the genomic variations in pancreatic cancer, and the resulting potential diagnostic and therapeutic implications.

Hypoxia pathway genetic variants predict survival of non-small-cell lung cancer patients receiving platinum-based chemotherapy

Hypoxia is a hallmark of solid tumors and has been implicated in the development of advanced disease and poor clinical outcome. In this multi-stage study, we aimed to assess whether genetic variations in hypoxia pathway genes might affect overall survival (OS) in patients with advanced-stage non-small cell lung cancer (NSCLC). We genotyped 598 potentially functional and tagging single nucleotide polymorphisms (SNPs) in 42 genes of the hypoxia pathway in 602 advanced stage NSCLC patients who received platinum-based chemotherapy or chemoradiation (discovery phase). Significant SNPs were validated in an additional 278 advanced stage patients (validation phase). Cox proportional hazard regression analysis was used to evaluate the association of each SNP with OS. Results showed in chemotherapy only group the median survival time (MST) of NSCLC patients with RPA1: rs2270412 AA+GA genotype versus GG genotype was 10.5 versus 12.7 month [P = 0.004, hazard ratio (HR) = 1.42, 95% CI: 1.16-1.74, combined set]. The MST of patients with EXO1: rs9350 GA+AA genotype versus GG genotypes was 13.2 months versus 11.5 months (P = 0.009, HR = 0.70, 95% CI: 0.56-0.87, combined set). Patients harboring two unfavorable genotypes had a 2.02-fold increased risk of death (P = 3.16E-6) and chemoradiation would improve survival for them (HR = 0.75, 95% CI: 0.51-1.10, P = 0.27, combined set). The MST for patients with 0, 1, and 2 unfavorable genotypes was 13.2, 12.7 and 8.9 months, respectively (P = 0.0002, combined set). In summary, two variants in RPA1 and EXO1 were associated with poor survival in NSCLC patients treated by platinum-based chemotherapy. Adding radiotherapy could improve survival in patients harboring these risk genotypes.

Verification of TREX1 as a promising indicator of judging the prognosis of osteosarcoma

Background

The study aimed to explore the correlation between the expression of TREX1 and the metastasis and the survival time of patients with osteosarcoma as well as biological characteristics of osteosarcoma cells for the prognosis judgment of osteosarcoma.

Method

The correlation between the expression of TREX1 protein and the occurrence of pulmonary metastasis in 45 cases of osteosarcoma was analyzed. The CD133⁺ and CD133⁻ cell subsets of osteosarcoma stem cells were sorted by the flow cytometry. The tumorsphere culture, clone formation, growth curve, osteogenic and adipogenic differentiation, tumor-formation ability in nude mice, sensitivity of chemotherapeutic drugs, and other cytobiology behaviors were compared between the cell subsets in two groups; the expressions of stem cell-related genes Nanog and Oct4 were compared; The expressions of TREX1 protein and mRNA were compared between the cell subsets in two groups. The data was statistically analyzed. The measurement data between the two groups were compared using t test. The count data between the two groups were compared using χ² test and Kaplan–Meier survival analysis. A P value <0.05 indicated that the difference was statistically significant.

Results

The expression of TREX1 protein in patients with osteosarcoma in the metastasis group was significantly lower than that in the non-metastasis group. The difference was statistically significant (P < 0.05). Up to the last follow-up visit, the former average survival time was significantly lower than that of the latter, and the difference was statistically significant (P < 0.05). The expression of TREX1 in human osteosarcoma CD133⁺ cell subsets was significantly lower than that in CD133^- cell subsets. Stemness-related genes Nanog and Oct4 were highly expressed in human osteosarcoma CD133⁺ cell subsets with lower expression of TREX1; the biological characteristics identification experiment showed that human CD133⁺ cell subsets with low TREX1 expression could form tumorspheres, the number of colony forming was more, the cell proliferation ability was strong, the osteogenic and adipogenic differentiation potential was big, the tumor-forming ability in nude mice was strong, and the sensibility of chemotherapeutics drugs on cisplatin was low.

Conclusions

The expression of TREX1 may be related to metastasis in patients with osteosarcoma. The expression of TREX1 was closely related to the cytobiology characteristics of osteosarcoma stem cell. TREX1 can play an important role in the occurrence and development processes. And, TREX1 is expected to become an effective new index for the evaluation of the prognosis.

Association of genetic polymorphisms with survival of pancreatic ductal adenocarcinoma patients

Germline genetic variability might contribute, at least partially, to the survival of pancreatic ductal adenocarcinoma (PDAC) patients. Two recently performed genome-wide association studies (GWAS) on PDAC overall survival (OS) suggested (P < 10(-5)) the association between 30 genomic regions and PDAC OS. With the aim to highlight the true associations within these regions, we analyzed 44 single-nucleotide polymorphisms (SNPs) in the 30 candidate regions in 1722 PDAC patients within the PANcreatic Disease ReseArch (PANDoRA) consortium. We observed statistically significant associations for five of the selected regions. One association in the CTNNA2 gene on chromosome 2p12 [rs1567532, hazard ratio (HR) = 1.75, 95% confidence interval (CI) 1.19-2.58, P = 0.005 for homozygotes for the minor allele] and one in the last intron of the RUNX2 gene on chromosome 6p21 (rs12209785, HR = 0.88, 95% CI 0.80-0.98, P = 0.014 for heterozygotes) are of particular relevance. These loci do not coincide with those that showed the strongest associations in the previous GWAS. In silico analysis strongly suggested a possible mechanistic link between these two SNPs and pancreatic cancer survival. Functional studies are warranted to confirm the link between these genes (or other genes mapping in those regions) and PDAC prognosis in order to understand whether these variants may have the potential to impact treatment decisions and design of clinical trials.

Impact of Polymorphic Variations of Gemcitabine Metabolism, DNA Damage Repair, and Drug-Resistance Genes on the Effect of High-Dose Chemotherapy for Relapsed or Refractory Lymphoid Malignancies

The goal of this study was to determine whether single nucleotide polymorphisms (SNPs) in genes involved in gemcitabine metabolism, DNA damage repair, multidrug resistance, and alkylator detoxification influence the clinical outcome of patients with refractory/relapsed lymphoid malignancies receiving high-dose gemcitabine/busulfan/melphalan (Gem/Bu/Mel) with autologous stem cell support. We evaluated 21 germline SNPs of the gemcitabine metabolism genes CDA, deoxycytidine kinase, and hCNT3; DNA damage repair genes RECQL, X-ray repair complementing 1, RAD54L, ATM, ATR, MLH1, MSH2, MSH3, TREX1, EXO1, and TP73; and multidrug-resistance genes MRP2 and MRP5; as well as glutathione-S-transferase GSTP1 in 153 patients with relapsed or refractory lymphoma or myeloma receiving Gem/Bu/Mel. We studied the association of genotypes with overall survival (OS), progression-free survival (PFS), and nonhematological grade 3 or 4 toxicity. CDA C111T and TREX1 Ex14-460C>T genotypes had a significant effect on OS (P = .007 and P = .005, respectively), and CDA C111T, ATR C340T, and EXO1 P757L genotypes were significant predictors for severe toxicity (P = .037, P = .024, and P = .025, respectively) in multivariable models that adjusted for clinical variables. The multi-SNP risk score analysis identified the combined genotypes of TREX1 Ex14-460 TT and hCNT3 Ex5 +25A>G AA as significant predictors for OS and the combination of MRP2 Ex10 + 40GG/GA and MLH1 IVS12-169 TT as significant predictor for PFS. Polymorphic variants of certain genes involved in gemcitabine metabolism and DNA damage repair pathways may be potential biomarkers for clinical outcome in patients with refractory/relapsed lymphoid tumors receiving Gem/Bu/Mel.

Identification of proteins interacting with protein kinase C-δ in hyperthermia-induced apoptosis and thermotolerance of Tca8113 cells

The purpose of the present study was to investigate the differential proteins that interact with protein kinase C‑δ (PKC‑δ) in hyperthermia‑induced apoptosis as well as thermotolerance in Tca8113 cells, and furthermore, to investigate the mechanisms of these processes in tumor cells. Activation of PKC‑δ was previously indicated to be involved in the heat sensitivity and thermal resistance of tongue squamous carcinoma cells. Tca8113 cell apoptosis was induced by incubation at 43˚C for 80 min and the thermotolerant Tca8113 cells (TT‑Tca8113) were generated through a gradient temperature‑elevating method. The apoptotic rate of the cells was determined by flow cytometry, while cleavage and activation of PKC‑δ were analyzed by western blot analysis. The proteins that interacted with PKC‑δ in the Tca8113 and TT‑Tca8113 cells were identified by co‑immunoprecipitation coupled with mass spectrometry. Co‑immunoprecipitation analysis followed by electrospray ionization mass spectrometric analysis were utilized to identify the pro‑ and anti‑apoptotic proteins that interacted with PKC‑δ. Significant cell apoptosis was observed in Tca8113 cells following hyperthermia, and the apoptotic rate was significantly higher than that in the control group (P<0.05). Marked PKC‑δ cleavage fragmentation was also identified. By contrast, the apoptotic rate of the TT‑Tca8113 cells was not significantly increased following hyperthermia and no PKC‑δ cleavage fragmentation was observed. Among the proteins interacting with PKC‑δ, 39 were found to be involved in the promotion of apoptosis and 16 in the inhibition of apoptosis of Tca8113 cells; these proteins were known to be involved in the regulation of cell proliferation, apoptosis, transcription and intracellular protein transport. The results of the present study provided evidence that PKC‑δ is a crucial factor in the heat sensitivity and thermal resistance of tongue squamous carcinoma cells and elucidated the underlying molecular basis, which may aid in the improvement of hyperthermic cancer treatments.

Neoadjuvant therapy for pancreas cancer: Past lessons and future therapies

Pancreatic adenocarcinoma remains a most deadly malignancy, with an overall 5-year survival of 5%. A subset of patients will be diagnosed with potentially resectable disease, and while complete surgical resection provides the only chance at cure, data from trials of postoperative chemoradiation and/or chemotherapy demonstrate a modest survival advantage over those patients who undergo resection alone. As such, most practitioners believe that completion of multimodality therapy is the optimal treatment. However, the sequence of surgery, chemotherapy and radiation therapy is frequently debated, as patients may benefit from a neoadjuvant approach by initiating chemotherapy and/or chemoradiation prior to resection. Here we review the rationale for neoadjuvant therapy, which includes a higher rate of completion of multimodality therapy, minimizing the risk of unnecessary surgical resection for patients who develop early metastatic disease, improved surgical outcomes and the potential for longer overall survival. However, there are no prospective, randomized studies of the neoadjuvant approach compared to a surgery-first strategy; the established and ongoing investigations of neoadjuvant therapy for pancreatic cancer are discussed in detail. Lastly, as the future of therapeutic regimens is likely to entail patient-specific genetic and molecular analyses, and the treatment that is best applied based on those data, a review of clinically relevant biomarkers in pancreatic cancer is also presented.

DNA repair gene polymorphisms and clinical outcome of patients with primary small cell carcinoma of the esophagus

Polymorphisms in DNA repair genes impact on the synthesis of DNA repair proteins that are crucial to the repair of DNA damages induced by chemotherapy and radiotherapy. We retrospectively examined whether there was an association between the selected six single nucleotide polymorphisms (SNPs) of five DNA repair genes (PARP1-Val762Ala, XRCC1-Arg194Trp, XRCC1-Arg399Gln, XPC-Lys939Gln, BRCA1-Lys1183Arg, and BRCA2-Asn372His) and the clinical outcome of patients with primary small cell carcinoma of esophagus (SCCE), and it showed that the median progression-free survival (PFS) and the overall survival (OS) were 11.8 versus 9.7 months (P = 0.041) and 17.4 versus 14.8 months (P = 0.032) for patients carrying the variant allele (T/C + C/C) and the wild-type allele (T/T) of PARP1-Val762Ala polymorphism, respectively. However, no statistical significance was observed in the other five polymorphic loci (P > 0.05). When these six SNPs were combined, however, patients with at least three variant genotypes had significantly longer PFS and OS compared with those carrying less than three variant genotypes (P = 0.009 and P = 0.007, respectively). The presence of at least three polymorphic variants in certain DNA repair genes may impact on patient survival and could be a potential genomic predictor of clinical response to DNA-damaging treatment in SCCE patients.

The prognostic significance of polymorphisms in hMLH1/hMSH2 for colorectal cancer

We aimed to investigate the associations between single-nucleotide polymorphisms (SNPs) in two mismatch repair genes (hMLH1 and hMSH2) and colorectal cancer (CRC) prognosis in Northeast China. We genotyped 387 patients for 10 SNPs in hMLH1 and hMSH2, using polymerase chain reaction restriction fragment length polymorphism approach. Associations between genotypes and overall survival (OS) were estimated using hazard ratios (HRs) and 95 % confidence intervals (CIs). Two SNPs of hMLH1 (hMLH1 -93G>A and IVS3-1403A>T) were significantly associated with OS of CRC in dominant model and recessive model, respectively. For hMLH1 -93G>A, the adjusted HR equaled 0.66 (95 % CI 0.45-0.99, p = 0.04). As for hMLH1 IVS3-1403A>T, the adjusted HR equaled 1.90 (95 % CI 1.14-3.17, p = 0.01). When stratified by tumor location, hMLH1 -93G>A and IVS3-1403A>T were associated with colon cancer survival (for hMLH1 -93G>A, AA+AG vs. GG, HRadj = 0.34, 95 % CI 0.17-0.68, p < 0.01; for hMLH1 IVS3-1403A>T, AT vs. AA, HR(adj) = 2.20, 95 % CI 1.11-4.36, p = 0.02), rather than rectal cancer. None of SNPs located at hMSH2 were significantly associated with prognosis of CRC. Our findings suggested that common variants in hMLH1 may serve as a predictor of CRC survival.

Variations in mismatch repair genes and colorectal cancer risk and clinical outcome

DNA mismatch repair (MMR) deficiency is one of the best understood forms of genetic instability in colorectal cancer (CRC). CRC is routinely cured by 5-fluorouracil (5-FU)-based chemotherapy, with a prognostic effect and resistance to such therapy conferred by MMR status. In this study, we aimed to analyse the effect of genetic variants in classical coding regions or in less-explored predicted microRNA (miRNA)-binding sites in the 3' untranslated region (3'UTR) of MMR genes on the risk of CRC, prognosis and the efficacy of 5-FU therapy. Four single nucleotide polymorphisms (SNPs) in MMR genes were initially tested for susceptibility to CRC in a case-control study (1095 cases and 1469 healthy controls). Subsequently, the same SNPs were analysed for their role in survival on a subset of patients with complete follow-up. Two SNPs in MLH3 and MSH6 were associated with clinical outcome. Among cases with colon and sigmoideum cancer, carriers of the CC genotype of rs108621 in the 3'UTR of MLH3 showed a significantly increased survival compared to those with the CT + TT genotype (log-rank test, P = 0.05). Moreover, this polymorphism was also associated with an increased risk of relapse or metastasis in patients with heterozygous genotype (log-rank test, P = 0.03). Patients carrying the CC genotype for MSH6 rs1800935 (D180D) and not undergoing 5-FU-based chemotherapy showed a decreased number of recurrences (log-rank test, P = 0.03). No association with CRC risk was observed. We provide the first evidence that variations in potential miRNA target-binding sites in the 3'UTR of MMR genes may contribute to modulate CRC prognosis and predictivity of therapy.

Biomarkers of TGF-β signaling pathway and prognosis of pancreatic cancer

Background

Transforming growth factor (TGF)-β signaling pathway, may act both as a tumor suppressor and as a tumor promoter in pancreatic cancer, depending on tumor stage and cellular context. TGF-β pathway has been under intensive investigation as a potential therapeutic target in the treatment of cancer. We hypothesized a correlation between TGF-βR2/SMAD4 expression in the tumor, plasma TGF-β1 ligand level, genetic variation in TGF-B pathway and prognosis of pancreatic cancer.

Method

We examined TGF-βR2 and SMAD4 protein expression in biopsy or surgical samples from 91 patients with pancreatic ductal adenocarcinoma (PDAC) using immunohistochemistry. Plasma level of TGF-β1 was measured in 644 patients with PDAC using ELISA. Twenty-eight single nucleotide polymorphisms (SNP) of the TGF-β1, TGF-β2, TGF-β3, TGF-βR1, TGF-βR2, and SMAD4 genes were determined in 1636 patients with PDAC using the Sequenom method. Correlation between protein expression in the tumor, plasma TGF-β1 level, and genotypes with overall survival (OS) was evaluated with Cox proportional regression models.

Results

The expression level of TGF-βR2 and SMAD4 as an independent marker was not associated with OS. However, patients with both low nuclear staining of TGF-βR2 and high nuclear staining of SMAD4 may have better survival (P = 0.06). The mean and median level of TGF-β1 was 15.44 (SD: 10.99) and 12.61 (interquartile range: 8.31 to 19.04) ng/ml respectively. Patients with advanced disease and in the upper quartile range of TGF-β1 level had significantly reduced survival than those with low levels (P = 0.02). A significant association of SMAD4 SNP rs113545983 with overall survival was observed (P<0.0001).

Conclusion

Our data provides valuable baseline information regarding the TGF-β pathway in pancreatic cancer, which can be utilized in targeted therapy clinical trials. High TGF-β1 plasma level, SMAD4 SNP or TGF-βR2/SMAD4 tumor protein expression may suggest a dependence on this pathway in patients with advanced pancreatic cancer.

Growth inhibition of pancreatic cancer cells by histone deacetylase inhibitor belinostat through suppression of multiple pathways including HIF, NFkB, and mTOR signaling in vitro and in vivo

Pancreatic ductal adenocarcinoma is a devastating disease with few therapeutic options. Histone deacetylase inhibitors are a novel therapeutic approach to cancer treatment; and two new pan-histone deacetylase inhibitors (HDACi), belinostat and panobinostat, are undergoing clinical trials for advanced hematologic malignancies, non-small cell lung cancers and advanced ovarian epithelial cancers. We found that belinostat and panobinostat potently inhibited, in a dose-dependent manner, the growth of six (AsPc1, BxPc3, Panc0327, Panc0403, Panc1005, MiaPaCa2) of 14 human pancreatic cancer cell lines. Belinostat increased the percentage of apoptotic pancreatic cancer cells and caused prominent G2 /M growth arrest of most pancreatic cancer cells. Belinostat prominently inhibited PI3K-mTOR-4EBP1 signaling with a 50% suppression of phorphorylated 4EBP1 (AsPc1, BxPc3, Panc0327, Panc1005 cells). Surprisingly, belinostat profoundly blocked hypoxia signaling including the suppression of hypoxia response element reporter activity; as well as an approximately 10-fold decreased transcriptional expression of VEGF, adrenomedullin, and HIF1α at 1% compared to 20% O2 . Treatment with this HDACi decreased levels of thioredoxin mRNA associated with increased levels of its endogenous inhibitor thioredoxin binding protein-2. Also, belinostat alone and synergistically with gemcitabine significantly (P = 0.0044) decreased the size of human pancreatic tumors grown in immunodeficiency mice. Taken together, HDACi decreases growth, increases apoptosis, and is associated with blocking the AKT/mTOR pathway. Surprisingly, it blocked hypoxic growth related signals. Our studies of belinostat suggest it may be an effective drug for the treatment of pancreatic cancers when used in combination with other drugs such as gemcitabine.

Systemic therapies for pancreatic cancer--the role of pharmacogenetics

Effective systemic treatment of pancreatic cancer remains a major challenge, with progress hampered by drug resistance and treatment related toxicities. Currently available cytotoxic agents as monotherapy or in combination have provided only a modest survival benefit for patients with advanced disease. Disappointing phase III results with gemcitabine-based combinations in patients with advanced pancreatic cancer might be related to poor efficacy of systemic therapies in unselected patients. Future research strategies should prioritize identification of predictive markers through pharmacogenetic investigations. The individualization of patient treatment through pharmacogenetics may help to improve outcome by maximizing efficacy whilst lowering toxicity. This review provides an update on the pharmacogenetics of pancreatic cancer treatment and its influence on treatment benefits and toxicity.

Systemic therapies for pancreatic cancer--the role of pharmacogenetics

Effective systemic treatment of pancreatic cancer remains a major challenge, with progress hampered by drug resistance and treatment related toxicities. Currently available cytotoxic agents as monotherapy or in combination have provided only a modest survival benefit for patients with advanced disease. Disappointing phase III results with gemcitabine-based combinations in patients with advanced pancreatic cancer might be related to poor efficacy of systemic therapies in unselected patients. Future research strategies should prioritize identification of predictive markers through pharmacogenetic investigations. The individualization of patient treatment through pharmacogenetics may help to improve outcome by maximizing efficacy whilst lowering toxicity. This review provides an update on the pharmacogenetics of pancreatic cancer treatment and its influence on treatment benefits and toxicity.

A replication study and genome-wide scan of single-nucleotide polymorphisms associated with pancreatic cancer risk and overall survival

PURPOSE

To explore the effects of single-nucleotide polymorphisms (SNP) on pancreatic cancer risk and overall survival (OS).

EXPERIMENTAL DESIGN

The germ line DNA of 531 pancreatic cancer cases and 305 healthy controls from a hospital-based study was genotyped at SNPs previously reported to be associated with pancreatic cancer risk or clinical outcome. We analyzed putative risk SNPs for replication of their reported effects on risk and tested for novel effects on OS. Similarly, we analyzed putative survival-associated SNPs for replication of their reported effects on OS and tested for novel effects on risk. Finally, we conducted a genome-wide association study (GWAS) of OS using a subset of 252 cases, with two subsequent validation sets of 261 and 572 patients, respectively.

RESULTS

Among seven risk SNPs analyzed, two (rs505922 and rs9543325) were associated with risk (P < 0.05). Among 24 survival-associated SNPs analyzed, one (rs9350) was associated with OS (P < 0.05). No putative risk SNPs or putative survival-associated SNPs were found to be associated with OS or risk, respectively. Furthermore, our GWAS identified a novel SNP [rs1482426, combined stage I and II, P = 1.7 × 10(-6), per-allele HR, 1.74; 95% confidence interval (CI), 1.38-2.18] to be putatively associated with OS.

CONCLUSIONS

The effects of SNPs on pancreatic cancer risk and OS were replicated in our study, although further work is necessary to understand the functional mechanisms underlying these effects. More importantly, the putative association with OS identified by GWAS suggests that GWAS may be useful in identifying SNPs associated with clinical outcome in pancreatic cancer.

The -409 C/T genotype of PRSS1 protects against pancreatic cancer in the Han Chinese population

BACKGROUND AND AIMS

The high mortality rate of pancreatic cancer is a bottleneck for further treatment with long-term efficacy. Thus, it is urgent to identify new methods to accurately predict the early onset of pancreatic cancer. We hypothesized that the different genotypes of cationic trypsinogen (PRSS1) gene could confer susceptibility and/or resistance to pancreatic cancer in the Han Chinese population.

METHODS

The genotypes of PRSS1 were determined in 154 patients with pancreatic cancer and in a control group of 520 healthy individuals of Han Chinese descent. Clinical information was obtained, single-nucleotide polymorphisms (SNPs) of the PRSS1 gene were analyzed by direct sequencing, and the distribution of the genotypes were tested for Hardy-Weinberg equilibrium. Odds ratios and 95% confidence intervals were calculated by logistic regression analysis to estimate the associations between the different genotypes or haplotypes and the risk of pancreatic cancer.

RESULTS

Three SNPs (-409 C/T, -204 A/C, and c.486 C/T) were identified. A case-control analysis revealed a 0.118-fold (95% CI: 0.037-0.653), 0.842-fold (95% CI: 0.177-4.010), and 0.750-fold (95% CI: 0.519-1.085) change in risk of developing pancreatic cancer for individuals harboring these SNPs, respectively. The individuals with the -409 C/T genotype tended to have a reduced risk compared to those who carried the -409 T/T genotype. A protective effect was observed for the C(-409)-A(-204)-C(486) haplotype compared to the T(-409)-A(-204)-T(486) haplotype (OR = 0.115, 95% CI: 0.016-0.849) or compared to the T(-409)-A(-204)-C(486) haplotype (OR = 0.090, 95% CI: 0.012-0.667). Serum levels of trypsin in patients with the -409 C/T genotype were only one-fourth that of those with the -409 T/T genotype and only one-third that of the healthy controls.

CONCLUSIONS

The -409 C/T genotype of PRSS1 was revealed to be a protective factor against pancreatic cancer in the Han Chinese population.

The significance of Exonuclease 1 K589E polymorphism on hepatocellular carcinoma susceptibility in the Turkish population: a case-control study

Exonuclease 1 (Exo 1) is an important nuclease involved in mismatch repair system that contributes to maintain genomic stability, to modulate DNA recombination, and to mediate cell cycle arrest. A guanine (G)/adenine (A) common single nucleotide polymorphism at first position of codon 589 in Exo 1 gene determines a glutamic acid (Glu, E) to lysine (Lys, K) (K589E) aminoacidic substitution which may alter cancer risk by influencing the activity of Exo 1 protein. Exo 1 K589E polymorphism has been studied in various cancers, but its association with hepatocellular carcinoma (HCC) has yet to be investigated. To determine the association of the Exo 1 K589E polymorphism with the risk of HCC development in a Turkish population, a hospital-based case-control study was designed consisting of 224 subjects with HCC and 224 cancer-free control subjects matched for age, gender, smoking and alcohol status. The genotype frequency of the Exo 1 K589E polymorphism was determined by using a polymerase chain reaction-restriction fragment length polymorphism assay. Our data shows that the Lys/Lys genotype of the Exo 1 K589E polymorphism is associated with increased risk of HCC development in this Turkish population [odds ratio (OR) = 2.15, 95% confidence interval (CI): 1.13-4.09, P = 0.02]. Furthermore, according to stratified analysis, a significant association was observed between the homozygote Lys/Lys genotype and HCC risk in the subgroups of male gender (OR = 2.67, 95% CI: 1.27-5.61, P = 0.009) and patients with non-viral-related HCC (OR = 3.14, 95% CI: 1.09-8.99, P = 0.03). Because our results suggest for the first time that the Lys/Lys homozygote genotype of Exo 1 K589E polymorphism may be a genetic susceptibility factor for HCC in the Turkish population, further independent studies are required to validate our findings in a larger series, as well as in patients of different ethnic origins.

Association between DNA-repair polymorphisms and survival in pancreatic cancer patients treated with combination chemotherapy

AIM

This multicenter study evaluated the association of 11 candidate polymorphisms in eight genes with outcome of pancreatic cancer patients treated with the equivalent polychemotherapeutic regimens: cisplatin/epirubicin/capecitabine/gemcitabine, cisplatin/docetaxel/capecitabine/gemcitabine and gemcitabine/capecitabine plus epirubicin/cisplatin intra-arterial infusion.

PATIENTS & METHODS

Towards this end, polymorphisms were assessed in DNA from 122 pancreatic cancer stage-III/IV patients, and their associations with toxicity/response and progression-free survival (PFS) and overall survival were evaluated using Pearson-χ(2) and log-rank test.

RESULTS

Patients harboring XPD Gln751Gln, XPD Asp312Asn + Asn312Asn or XRCC1 Arg399Gln + Gln399Gln genotypes had a worse prognosis. XPD Gln751Gln (hazard ratio: 1.9; p = 0.003), as well as a combination of over two risk genotypes (hazard ratio: 2.7; p < 0.001), emerged as independent predictors for death risk at multivariate analysis. No correlations were observed with toxicity. Conversely, XPD Gln751Gln was associated with shorter PFS, while the lack of association with overall survival/PFS in gemcitabine monotherapy-treated patients suggested its role only for platinum-based regimens.

CONCLUSION

Polymorphisms of DNA-repair genes appear to be candidate biomarkers of primary resistance to gemcitabine/cisplatin-based polychemotherapeutic regimens. The relatively small sample size, coupled with the retrospective and exploratory design of the present study, imply that these results should be considered as hypothesis generators, and should be further evaluated in larger and adequately designed retrospective/prospective studies.

Genetic effects and modifiers of radiotherapy and chemotherapy on survival in pancreatic cancer

OBJECTIVES

Germ-line genetic variation may affect clinical outcomes of cancer patients. We applied a candidate-gene approach to evaluate the effect of putative markers on survival of patients with pancreatic cancer. We also examined gene-radiotherapy and gene-chemotherapy interactions, aiming to explain interindividual differences in treatment outcomes.

METHODS

In total, 211 patients with pancreatic cancer were recruited in a population-based study. Sixty-four candidate genes associated with cancer survival or treatment response were selected from existing publications. Genotype information was obtained from a previous genome-wide association study data set. The main effects of genetic variation and gene-specific treatment interactions on overall survival were examined by proportional hazards regression models.

RESULTS

Fourteen genes showed evidence of association with pancreatic cancer survival. Among these, rs1760217, located at the DPYD gene; rs17091162 at SERPINA3; and rs2231164 at ABCG2 had the lowest P of 10(-4.60), 0.0013, and 0.0023, respectively. We also observed that 2 genes, RRM1 and IQGAP2, had significant interactions with radiotherapy in association with survival, and 2 others, TYMS and MET, showed evidence of interaction with 5-fluorouracil and erlotinib, respectively.

CONCLUSIONS

Our study suggested significant associations between germ-line genetic polymorphisms and overall survival in pancreatic cancer, as well as survival interactions between various genes and radiotherapy and chemotherapy.

DNA mismatch repair network gene polymorphism as a susceptibility factor for pancreatic cancer

DNA repair plays a critical role in human cancers. We hypothesized that DNA mismatch repair gene variants are associated with risk of pancreatic cancer. We retrospectively genotyped 102 single-nucleotide polymorphisms (SNPs) of 13 mismatch repair related genes in 706 patients with pancreatic cancer and 706 cancer-free controls using the mass spectroscopy-based MassArray method. Association of genotype with pancreatic cancer risk was tested by multivariate logistic regression models. A significance level of P ≤ 0.0015 was set at the false discovery rate (FDR) <1% using the Beta-Uniform Mixture method. We found 28 SNPs related to altered pancreatic cancer risk (P < 0.05). Adjusting for multiple comparisons, MGMT I143V AG/GG, PMS2 IVS1-1121C > T TC/TT, and PMS2L3 Ex1 + 118C > T CT/TT genotypes showed significant main effects on pancreatic cancer risk at FDR <1% with OR (95% CI) of 0.60 (0.46-0.80), 1.44 (1.14-1.81), and 5.54 (2.10-14.61), respectively (P ≤ 0.0015). To demonstrate genotype-phenotype association, we measured O(6)-ethylguanosine (O(6)-EtGua) adduct levels in vitro by immunoslot blot assay in lymphocytes treated with N-ethyl-N-nitrosourea (ENU) in 297 case/control subjects. MGMT I143V GG, MGMT K178R GG, MSH6 G39E AG/AA, PMS2L3 IVS3 + 9A > G GA and TP73 IVS1-7449G > C CG/CC genotypes correlated with a higher level of ENU-induced DNA adducts. Haplotypes of MGMT, MSH6, PMS2, PMS2L3, and TP73 were significantly associated with pancreatic cancer risk (P ≤ 0.0015). Our findings suggest that mismatch repair gene variants may affect susceptibility to pancreatic cancer.

Next generation histone deacetylase inhibitors: the answer to the search for optimized epigenetic therapies?

INTRODUCTION

HDAC inhibitors have demonstrated potent anticancer activities in preclinical and clinical studies. Currently, two drugs (SAHA and romidepsin) have gained the FDA approval for the treatment of cutaneous T-cell lymphoma. Clinical efficacy of HDAC inhibitors has been observed in advanced hematological malignancies, while response in other cancers has been in most cases unpredictable and often rather limited. The search for new molecules with the potential to overcome the limitations of the first HDAC inhibitors has become a primary goal in the field of epigenetic drug discovery as well as drugs acting on other chromatin modifying enzymes.

AREAS COVERED

The article shortlists seven new HDAC inhibitors that have recently entered clinical studies as representative examples of next generation drugs. The most recently published preclinical profile is reviewed, together with the first clinical data for these compounds. The article then focuses on challenges faced during the progress of first generation HDAC inhibitors and analyzes whether these new compounds are likely to provide a solution to the existing issues and needs.

EXPERT OPINION

Next generation HDAC inhibitors have the 'best-in-class' potential, particularly regarding potency and in vivo exposure. However, several issues remain unresolved. For example, none of the presented compounds appears to have a significantly different selectivity profile towards various HDAC isoforms and, thus, none of them may provide a further elucidation between the toxicity seen in more advanced HDAC inhibitors and isoform selectivity. Additionally, a need for a continuous effort on target validation is seen as a necessary requirement for further progress in the field.

DNA mismatch repair gene polymorphisms affect survival in pancreatic cancer

PURPOSE

DNA mismatch repair (MMR) maintains genomic stability and mediates cellular response to DNA damage. We aim to demonstrate whether MMR genetic variants affect overall survival (OS) in pancreatic cancer.

MATERIALS AND METHODS

Using the Sequenom method in genomic DNA, we retrospectively genotyped 102 single-nucleotide polymorphisms (SNPs) of 13 MMR genes from 706 patients with pancreatic adenocarcinoma seen at The University of Texas MD Anderson Cancer Center. Association between genotype and OS was evaluated using multivariable Cox proportional hazard regression models.

RESULTS

At a false discovery rate of 1% (p ≤ .0015), 15 SNPs of EXO1, MLH1, MSH2, MSH3, MSH6, PMS2, PMS2L3, TP73, and TREX1 in patients with localized disease (n = 333) and 6 SNPs of MSH3, MSH6, and TP73 in patients with locally advanced or metastatic disease (n = 373) were significantly associated with OS. In multivariable Cox proportional hazard regression models, SNPs of EXO1, MSH2, MSH3, PMS2L3, and TP73 in patients with localized disease, MSH2, MSH3, MSH6, and TP73 in patients with locally advanced or metastatic disease, and EXO1, MGMT, MSH2, MSH3, MSH6, PMS2L3, and TP73 in all patients remained significant predictors for OS (p ≤ .0015) after adjusting for all clinical predictors and all SNPs with p ≤ .0015 in single-locus analysis. Sixteen haplotypes of EXO1, MLH1, MSH2, MSH3, MSH6, PMS2, PMS2L3, RECQL, TP73, and TREX1 significantly correlated with OS in all patients (p ≤ .001).

CONCLUSION

MMR gene variants may have potential value as prognostic markers for OS in pancreatic cancer patients.

Association of multi-drug resistance gene polymorphisms with pancreatic cancer outcome

BACKGROUND

The purpose of this study was to identify single nucleotide polymorphisms (SNPs) of multidrug resistance genes that are associated with clinical outcome in patients with potentially resectable pancreatic adenocarcinoma who were treated with preoperative gemcitabine-based chemoradiotherapy at M. D. Anderson Cancer Center.

METHODS

We selected 8 SNPs of 7 drug resistance genes, including MDR1 (ABCB1), MRP1-5 (ABCC1-5), and BCRP (ABCG2), reported to be important in mediating drug resistance. Genotype was determined by the Taqman method. The associations of genotype with tumor response to therapy and overall survival (OS) were evaluated using log-rank test, Cox regression, and logistic regression models.

RESULTS

MRP5 A-2G AA genotype showed significant association with OS (log-rank P = .010). The hazard ratio (95% confidence interval) was 1.65 (1.11-2.45) after adjusting for clinical predictors. The MRP2 G40A GG genotype had a weak association with reduced OS (log-rank P = .097). A combined effect of the two genotypes on OS was observed. Patients with none of the adverse genotypes had a median survival time (MST) of 34.0 months, and those with 1-2 deleterious alleles had a significantly lower MST of 20.7 months (log-rank P = .006). MRP2 G40A GG genotype was also significantly associated with poor histological response to chemoradiotherapy (P = .028).

CONCLUSIONS

These observations suggest a potential role of polymorphic variants of drug resistance genes in predicting therapeutic efficacy and survival of patients with potentially resectable pancreatic cancer.

Glucose metabolism gene polymorphisms and clinical outcome in pancreatic cancer

BACKGROUND

Altered glucose metabolism is the most common metabolic hallmark of malignancies. The authors tested the hypothesis that glucose metabolism gene variations affect clinical outcome in pancreatic cancer.

METHODS

The authors retrospectively genotyped 26 single nucleotide polymorphisms from 5 glucose metabolism genes in 154 patients with localized disease and validated the findings in 552 patients with different stages of pancreatic adenocarcinoma. Association between genotypes and overall survival (OS) was evaluated using multivariate Cox proportional hazard regression models with adjustment for clinical predictors.

RESULTS

Glucokinase (GCK) IVS1 + 9652C > T and hexokinase 2 (HK2) N692N homozygous variants were significantly associated with reduced OS in the training set of 154 patients (P < .001). These associations were confirmed in the validation set of 552 patients and in the combined dataset of all 706 patients (P ≤ .001). In addition, HK2 R844K variant K allele was associated with a better survival in the validation set and the combined dataset (P ≤ .001). When data were further analyzed by disease stage, glutamine-fructose-6-phosphate transaminase (GFPT1) IVS14-3094T>C, HK2 N692N and R844K in patients with localized disease and GCK IVS1 + 9652C>T in patients with advanced disease were significant independent predictors for OS (P ≤ .001). Haplotype CGG of GPI and GCTATGG of HK2 were associated with better OS, respectively, with P values of .004 and .007.

CONCLUSIONS

The authors demonstrated that glucose metabolism gene polymorphisms affect clinical outcome in pancreatic cancer. These observations support a role of abnormal glucose metabolism in pancreatic carcinogenesis.

The activity of the lipophilic nucleoside derivatives elacytarabine and CP-4126 in a panel of tumor cell lines resistant to nucleoside analogues

The clinical activity of pyrimidine analogues (araC and gemcitabine) is impaired by different mechanisms of resistance and several efforts to overcome this problem have been undertaken. Elacytarabine (CP-4055, araC-5'elaidic acid ester) and CP-4126 (gemcitabine-5'elaidic acid ester) are lipophilic fatty acid derivatives of the nucleoside analogues araC and gemcitabine, respectively, that are currently investigated in clinical trials in solid tumors and hematological malignancies. Here, we present results on the activity of elacytarabine and CP-4126 in a panel of tumor cell lines that are resistant to araC and gemcitabine and we discuss the potential use of these agents in the treatment of patients with drug resistance phenotypes. We conclude that elacytarabine and CP-4126 are active in cells with deficient nucleoside membrane transport and altered mismatch repair. These results should be taking into consideration for future clinical development of elacyatrabine and CP-4126.

Insulin-like growth factor axis gene polymorphisms and clinical outcomes in pancreatic cancer

BACKGROUND & AIMS

Insulin-like growth factor (IGF)-axis mediated signaling pathways play an important role in pancreatic cancer development and progression. We examined whether IGF-axis gene variants are associated with clinical outcomes in pancreatic cancer.

METHODS

We retrospectively genotyped 41 single-nucleotide polymorphisms from 10 IGF-axis genes in 333 patients with localized pancreatic adenocarcinoma and validated the findings in 373 patients with advanced disease. Associations between genotype and overall survival (OS) were evaluated using multivariable Cox proportional hazard regression models.

RESULTS

IGF1 *8470T>C, IGF1R IVS2+46329T>C, IGFBP3 A32G, IRS1 G972R in patients with localized disease; IGF1R IVS20-3431A>G, IGF1R T766T, IGFBP3-202A>C, IRS1 IVS1+4315C>G, IRS1 G972R in patients with advanced disease; and IGF1R T766T, IGF2R L252V, IGFBP3 -202A>C, IRS1 IVS1+4315C>G, IRS1 G972R, IRS2 IVS1+5687T>C in all patients were significantly associated with OS (P<or=.007). Two haplotypes containing the variant allele of either IRS1 G972R or IVS1-10949G>A, and an IRS2 haplotype predicted worse OS (P<or=.002). A significant correlation between increased number of unfavorable genotypes and decreased OS was observed; patients with 0-1 (n=247), 2 (n=237), 3 (n=145), 4 (n=60), and 5-8 (n=17) unfavorable genotypes had median survival time of 24.2, 16.4, 14.4, 9.6, and 7.4 months, respectively (P<.001). Several single-nucleotide polymorphisms of IGF1R, IGF2R, and IRS1 gene were significantly associated with tumor response to therapy and disease stage.

CONCLUSIONS

These data suggest that individual genetic variations in the IGF axis pathway may predict worse survival in patients with pancreatic cancer. This information may identify population subgroups that could benefit from IGF(1)R-targeted agents.

A large-scale candidate gene approach identifies SNPs in SOD2 and IL13 as predictive markers of response to preoperative chemoradiation in rectal cancer

Neoadjuvant radiochemotherapy followed by total mesorectal excision is now the standard treatment for locally advanced rectal cancer. However, tumor response to chemoradiation varies widely among individuals and cannot be determined before the final pathologic evaluation. The aim of this study was to identify germline genetic markers that could predict sensitivity or resistance to preoperative radiochemotherapy (RT-CT) in rectal cancer. We evaluated the predictive value of 128 single-nucleotide polymorphisms (SNPs) in 71 patients preoperatively treated by RT-CT. The selected SNPs were distributed over 76 genes that are involved in various cellular processes such as DNA repair, apoptosis, proliferation or immune response. The SNPs superoxide dismutase 2 (SOD2) rs4880 (P=0.005) and interleukin-13 (IL13) rs1800925 (P=0.0008) were significantly associated with tumor response to chemoradiation. These results reinforce the idea of using germline polymorphisms for personalized treatment.

Systemic therapy for metastatic pancreatic adenocarcinoma

Systemic treatment of metastatic pancreatic adenocarcinoma achieves only modest benefits, with evidence indicating a survival advantage with 5-fluorouracil (5-FU) over best supportive care alone, and further advantage of single-agent gemcitabine over 5-FU. There are very few regimens better than single-agent gemcitabine despite multiple trials of cytotoxic and targeted agents. The addition of a platinum agent has improved response rate but not survival. The addition of erlotinib has improved survival but only by a small margin. The use of gemcitabine in multidrug regimens containing one or more of: a platinum agent; fluoropyrimidine; anthracycline; and taxane has demonstrated advantages in response rate, progression-free survival and, in one randomized study, overall survival. After gemcitabine failure, second-line therapy with oxaliplatin and 5-FU provides a further survival advantage. Further advances depend upon the current and future clinical trials investigating enhanced delivery of current agents, new agents and novel modalities, improved supportive care, and treatment more tailored to the individual patient and tumour.

Germline MLH1 and MSH2 mutations in Italian pancreatic cancer patients with suspected Lynch syndrome

Lynch syndrome is an inherited cancer syndrome caused by germline mutations in mismatch repair (MMR) genes MLH1, MSH2, MSH6 and PMS2. LS predisposes to high risk of early-onset colorectal, endometrial and other tumors. Patients with Lynch syndrome have also been shown to have an elevated risk for pancreatic cancer (PC). In this study, we aimed to estimate the frequency of suspected Lynch syndrome among a series of 135 PC patients. Further, we wanted to determine the frequency of MMR gene mutations in the suspected Lynch syndrome cases. We also aimed to verify the pathogenicity of any novel non-truncating variants we might detect with a functional assay. Based on personal and/or familial cancer history, 19 patients were classified as suspected Lynch syndrome cases. DNA material for mutation analysis was available for eleven of them. Four patients were found to carry a total of five MLH1 or MSH2 variants. Of these, MSH2-Q402X, MSH2-G322D, and MLH1-K618A had been previously reported, while the MSH2-E205Q and MSH2-V367I variants were novel. MSH2-Q402X is a known stop mutation and reported here for the first time here in association with PC. MLH1-K618A was found in the unaffected branch of a kindred, suggesting that it may be a polymorphism or a low penetrance variant. MSH2-G322D likely does not cause a MMR defect, although this variant has also been associated with breast cancer as indeed seen in our patient. The novel variants MSH2-E205Q and MSH2-V367I were found in the same patient. Both novel variants were however functional in the applied MMR assay. Our findings suggest that only a small subset of pancreatic cancer patients carry pathogenic MMR mutations.

Single nucleotide polymorphisms of gemcitabine metabolic genes and pancreatic cancer survival and drug toxicity

PURPOSE

To show whether single nucleotide polymorphisms (SNP) of drug metabolic genes were associated with toxicity of 2',2'-difluoro 2'-deoxycytidine (gemcitabine)-based chemoradiotherapy and overall survival (OS) of patients with pancreatic cancer.

EXPERIMENTAL DESIGN

We evaluated 17 SNPs of the CDA, dCK, DCTD, RRM1, hCNT1, hCNT2, hCNT3, and hENT1 genes in 154 patients with potentially resectable pancreatic adenocarcinoma who were enrolled in clinical trials at The University of Texas M.D. Anderson Cancer Center (Houston, TX) from February 1999 to January 2006, with follow-up until April 2009. Patients received neoadjuvant concurrent gemcitabine and radiation therapy with or without gemcitabine-cisplatin induction therapy. The association of genotypes with toxicity or OS was tested, respectively, by logistic regression and Cox regression analysis.

RESULTS

None of the 17 SNPs, individually, had a significant association with OS. A combined genotype effect of CDA A-76C, dCK C-1205T, DCTD T-47C, hCNT3 C-69T, hENT1 T-549C, and hENT1 C913T on OS was observed. Patients carrying 0 to 1 (n = 43), 2 to 3 (n = 77), or 4 to 6 (n = 30) variant alleles had median survival time of 31.5, 21.4, and 17.5 months, respectively. The hazard ratio of dying was 1.71 (95% confidence interval, 1.06-2.76) and 3.16 (95% confidence interval, 1.77-5.63) for patients carrying two to three or four to six at-risk genotypes (P = 0.028 and P < 0.001), respectively, after adjusting for clinical predictors. CDA C111T, dCK C-1205T, dCK A9846G, and hCNT3 A25G, individually and jointly, had a significant association with neutropenia toxicity.

CONCLUSIONS

These observations suggest that polymorphic variations of drug metabolic genes were associated with toxicity of gemcitabine-based therapy and OS of patients with resectable pancreatic cancer.