Epigenetic targeting in pancreatic cancer

Deubiquitinase UCHL5 stabilizes ELK3 to potentiate cancer stemness and tumor progression in pancreatic adenocarcinoma (PAAD)

Aberrant ubiquitin-proteasome system (UPS) contributes to tumorigeneisis or drug resistance of Pancreatic Adenocarcinoma (PAAD). Previous studies have implicated the deubiquitinase UCHL5 was abnormally expressed in multiple malignancies. However, little was reported about the specific roles of UCHL5 in PAAD. We aimed to identify the biological roles of UCHL5 in PAAD and demonstrate its prognostic significance. Differential analysis revealed that UCHL5 expressed highly in tumors versus normal tissues, like TCGA-PAAD, GSE28735, GSE15471 and collected samples. Patients with high UCHL5 expressions had worse survival outcomes relative to those with low UCHL5 levels. Experimental assays showed that UCHL5 overexpression could significantly enhance cell proliferation, colony formation and self-renewal capacities. UCHL5 could also promote PAAD migration in vitro and in vivo. Mechanistically, UCHL5 could directly deubiquitinate and stabilize ELK3 proteins. UCHL5 relied on accumulated ELK3 proteins to drive cell growth, stem-like properties and migration abilities. In addition, enrichment analysis based on RNA-seq data implicated that ELK3 mainly correlated with Notch1 signaling and ELK3 could notably elevate ELK3 mRNA levels. UCHL5 could thus promote self-renewal abilities of PAAD and targeting ELK3 could inhibit the stemness features. In contrast, UCHL5 deficiency could suppress PAAD stemness features, and ectopic expression of ELK3 could rescue this effect. Last of all, we utilized the UCHL5 inhibitor, b-AP15, to treat PAAD cells and found that b-AP15 could inhibit the growth of PAAD cells in a dose-dependent manner. Collectively, our study uncovered the underlying mechanisms of UCHL5/ELK3/Notch1 axis in PAAD progression and stemness maintaince, shedding light on individualized treatment and risk stratification for PAAD patients.

The histone deacetylase inhibitor M344 as a multifaceted therapy for pancreatic cancer

The histone deacetylase (HDAC) inhibitor vorinostat, used with gemcitabine and other therapies, has been effective in treatment of experimental models of pancreatic cancer. In this study, we demonstrated that M344, an HDAC inhibitor, is efficacious against pancreatic cancer in vitro and in vivo, alone or with gemcitabine. By 24 hours post-treatment, M344 augments the population of pancreatic cancer cells in G1, and at a later time point (48 hours) it increases apoptosis. M344 inhibits histone H3 deacetylation and slows pancreatic cancer cell proliferation better than vorinostat, and it does not decrease the viability of a non-malignant cell line more than vorinostat. M344 also elevates pancreatic cancer cell major histocompatibility complex (MHC) class I molecule expression, potentially increasing the susceptibility of pancreatic cancer cells to T cell lysis. Taken together, our findings support further investigation of M344 as a pancreatic cancer treatment.

A personalized approach to pancreatic ductal adenocarcinoma and its application in surgical practice

Pancreatic duct adenocarcinoma is an aggressive tumor which constitutes the fourth leading cause of cancer-related mortality in the USA. Despite the fact that surgery is an integral part of treatment, 5-year survival rates remain unfavorable, partly because of the complex genetic background, delayed diagnosis and also the absence of effective therapeutic approaches. To optimize surgery's results in recent years, the use of patients' genetic profile has been implemented through classification into subtypes; subtypes based on mutations which could efficiently lead oncologists to the path of targeted novel neoadjuvant regimens. This approach aims to achieve the most effective selection of patients undergoing surgery, to increase the number of potentially resectable tumors and also control micro-metastases, aiming to extend overall survival.

Evaluation of biomarkers, genetic mutations, and epigenetic modifications in early diagnosis of pancreatic cancer

BACKGROUND

Pancreatic cancer (PC) is one of the deadliest malignancies with an alarming mortality rate. Despite significant advancement in diagnostics and therapeutics, early diagnosis remains elusive causing poor prognosis, marred by mutations and epigenetic modifications in key genes which contribute to disease progression.

AIM

To evaluate the various biological tumor markers collectively for early diagnosis which could act as prognostic biomarkers and helps in future therapeutics of PC in Kashmir valley.

METHODS

A total of 50 confirmed PC cases were included in the study to evaluate the levels of carbohydrate antigen 19-9 (CA 19-9), tissue polypeptide specific antigen (TPS), carcinoembryonic antigen (CEA), vascular endothelial growth factor-A (VEGF-A), and epidermal growth factor receptor (EGFR). Mutational analysis was performed to evaluate the mutations in Kirsten rat sarcoma (KRAS), Breast cancer type 2 (BRCA-2), and deleted in pancreatic cancer-4 (DPC-4) genes. However, epigenetic modifications (methylation of CpG islands) were performed in the promoter regions of cyclin-dependent kinase inhibitor 2A (p16; CDKN2A), MutL homolog 1 (hMLH1), and Ras association domain-containing protein 1(RASSF1A) genes.

RESULTS

We found significantly elevated levels of biological markers CA 19-9 (P ≤ 0.05), TPS (P ≤ 0.05), CEA (P ≤ 0.001), and VEGF (P ≤ 0.001). Molecular genetic analysis revealed that KRAS gene mutation is predominant in codon 12 (16 subjects, P ≤ 0.05), and 13 (12 subjects, P ≤ 0.05). However, we did not find a mutation in DPC-4 (1203G > T) and BRCA-2 (617delT) genes. Furthermore, epigenetic modification revealed that CpG methylation in 21 (P ≤ 0.05) and 4 subjects in the promoter regions of the p16 and hMLH1 gene, respectively.

CONCLUSION

In conclusion, CA 19-9, TPS, CEA, and VEGF levels were significantly elevated and collectively have potential as diagnostic and prognostic markers in PC. Global data of mutation in the KRAS gene commonly in codon 12 and rare in codon 13 could augment the predisposition towards PC. Additionally, methylation of the p16 gene could also modulate transcription of genes thereby increasing the predisposition and susceptibility towards PC.

Methylation patterns partition pancreatic cancer into distinct prognostic subtypes

In the initiation and progression of pancreatic cancer, DNA methylation plays a critical role. The present study attempts to explore specific prognosis subtypes based on DNA methylation data and develop an epigenetic signature to predict the overall survival (OS) of patients with pancreatic cancer.147 samples were included in the training cohort, whereas the validation cohort included 226 samples. The 298 OS-related methylation sites in the training cohort were selected for consensus clustering, and the authors identified three subtypes with a significant difference in prognosis. Cluster1 was associated with poor OS, low-grade disease and high lymph node involvement. In addition, we identified 33 specific methylation sites in Cluster1. Subsequently, we developed a robust qualitative signature consisting of 14 methylation sites to individually predict OS in the training cohort, and the predictive accuracy of this model was confirmed in the validation cohort. Functional enrichment analysis showed that the selected genes in the model were mainly enriched in known cancer-related pathways. Patients were divided into high- and low-risk groups by the model, and a significant difference in OS was observed between these groups. Classification based on the modeling of a specific DNA methylation site can reveal the heterogeneity of pancreatic cancer and provide guidance for clinicians in predicting the prognosis of pancreatic cancer and providing personalized treatment.

HOXB5 promotes malignant progression in pancreatic cancer via the miR-6732 pathway

Background: Homeobox B5 (HOXB5) is associated with the poor prognosis of various cancer types. However, the specific mechanism by which HOXB5 promotes the malignant progression of pancreatic cancer (PC) remains to be determined.Methods: The Cancer Genome Atlas database indicated HOXB5 expression level correlated to PC prognosis. The biological functions of HOXB5 was confirmed by colony formation, migration, and invasion assays. The effects of HOXB5 on the expression of cancer stem cell and epithelial-mesenchymal transition markers were evaluated. The downstream target of HOXB5 was miR-6723, which was detected by transcriptional assay. A xenograft tumor model was established in nude mice for the assessment of the role of HOXB5 in tumor growth and metastasis.Results: PC tissues had higher HOXB5 expression levels than noncancerous tissues, and high HOXB5 expression was significantly associated with poor PC prognosis. HOXB5 knockdown suppressed clone formation and the proliferation, invasion, and migration of PC cells in vitro. Conversely, these activities were enhanced by HOXB5 overexpression. The HOXB5 that bound two synergy motifs regulated miR-6723 expression and contributed to PC malignant progression. The role of HOXB5 in promoting tumor growth and metastasis was verified in vivo. Further investigation revealed that Twist1 and Zeb1 expression levels were increased by HOXB5.Conclusions: HOXB5 overexpression was significantly correlated with poor PC prognosis. HOXB5 accelerated the malignant progression of PC by up-regulating miR-6723, which afforded PC cells stem-like properties and facilitated the epithelial-mesenchymal transition of PC cells.

Fluctuations of Histone Chemical Modifications in Breast, Prostate, and Colorectal Cancer: An Implication of Phytochemicals as Defenders of Chromatin Equilibrium

Natural substances of plant origin exert health beneficiary efficacy due to the content of various phytochemicals. Significant anticancer abilities of natural compounds are mediated via various processes such as regulation of a cell's epigenome. The potential antineoplastic activity of plant natural substances mediated by their action on posttranslational histone modifications (PHMs) is currently a highly evaluated area of cancer research. PHMs play an important role in maintaining chromatin structure and regulating gene expression. Aberrations in PHMs are directly linked to the process of carcinogenesis in cancer such as breast (BC), prostate (PC), and colorectal (CRC) cancer, common malignant diseases in terms of incidence and mortality among both men and women. This review summarizes the effects of plant phytochemicals (isolated or mixtures) on cancer-associated PHMs (mainly modulation of acetylation and methylation) resulting in alterations of chromatin structure that are related to the regulation of transcription activity of specific oncogenes, which are crucial in the development of BC, PC, and CRC. Significant effectiveness of natural compounds in the modulation of aberrant PHMs were confirmed by a number of in vitro or in vivo studies in preclinical cancer research. However, evidence concerning PHMs-modulating abilities of plant-based natural substances in clinical trials is insufficient.

LncRNA-MTA2TR functions as a promoter in pancreatic cancer via driving deacetylation-dependent accumulation of HIF-1α

Rationale: Hypoxia has been proved to contribute to aggressive phenotype of cancers, while functional and regulatory mechanism of long noncoding RNA (lncRNA) in the contribution of hypoxia on pancreatic cancer (PC) tumorigenesis is incompletely understood. The aim of this study was to uncover the regulatory and functional roles for hypoxia-induced lncRNA-MTA2TR (MTA2 transcriptional regulator RNA, AF083120.1) in the regulation of PC tumorigenesis. Methods: A lncRNA microarray confirmed MTA2TR expression in tissues of PC patients. The effects of MTA2TR on proliferation and metastasis of PC cells and xenograft models were determined, and the key mechanisms by which MTA2TR promotes PC were further dissected. Furthermore, the expression and regulation of MTA2TR under hypoxic conditions in PC cells were assessed. We also assessed the correlation between MTA2TR expression and PC patient clinical outcomes. Results: We found that metastasis associated protein 2 (MTA2) transcriptional regulator lncRNA (MTA2TR) was overexpressed in PC patient tissues relative to paired noncancerous tissues. Furthermore, we found that depletion of MTA2TR significantly inhibited PC cell proliferation and invasion both in vitro and in vivo. We further demonstrated that MTA2TR transcriptionally upregulates MTA2 expression by recruiting activating transcription factor 3 (ATF3) to the promoter area of MTA2. Consequentially, MTA2 can stabilize the HIF-1α protein via deacetylation, which further activates HIF-1α transcriptional activity. Interestingly, our results revealed that MTA2TR is transcriptionally regulated by HIF-1α under hypoxic conditions. Our clinical samples further indicated that the overexpression of MTA2TR was correlated with MTA2 upregulation, as well as with reduced overall survival (OS) in PC patients. Conclusions: These results suggest that feedback between MTA2TR and HIF-1α may play a key role in regulating PC tumorigenesis, thus potentially highlighting novel avenues PC treatment.

Engineering Multidimensional Evolutionary Forces to Combat Cancer

With advances in technology and bioinformatics, we are now positioned to view and manage cancer through an evolutionary lens. This perspective is critical as our appreciation for the role of tumor heterogeneity, tumor immune compartment, and tumor microenvironment on cancer pathogenesis and evolution grows. Here, we explore recent knowledge on the evolutionary basis of cancer pathogenesis and progression, viewing tumors as multilineage, multicomponent organisms whose growth is regulated by subcomponent fitness relationships. We propose reconsidering some current tenets of the cancer management paradigm in order to take better advantage of crucial fitness relationships to improve outcomes of patients with cancer. SIGNIFICANCE: Tumor and tumor immune compartment and microenvironment heterogeneity, and their evolution, are critical disease features that affect treatment response. The impact and interplay of these components during treatment are viable targets to improve clinical response. In this article, we consider how tumor cells, the tumor immune compartment and microenvironment, and epigenetic factors interact and also evolve during treatment. We evaluate the convergence of these factors and suggest innovative treatment concepts that leverage evolutionary relationships to limit tumor growth and drug resistance.

Epigenomics of Pancreatic Cancer: A Critical Role for Epigenome-Wide Studies

Several challenges present themselves when discussing current approaches to the prevention or treatment of pancreatic cancer. Up to 45% of the risk of pancreatic cancer is attributed to unknown causes, making effective prevention programs difficult to design. The most common type of pancreatic cancer, pancreatic ductal adenocarcinoma (PDAC), is generally diagnosed at a late stage, leading to a poor prognosis and 5-year survival estimate. PDAC tumors are heterogeneous, leading to many identified cell subtypes within one patient’s primary tumor. This explains why there is a high frequency of tumors that are resistant to standard treatments, leading to high relapse rates. This review will discuss how epigenetic technologies and epigenome-wide association studies have been used to address some of these challenges and the future promises these approaches hold.

Epigenetic reprogramming using 5-azacytidine promotes an anti-cancer response in pancreatic adenocarcinoma cells

Curative management of pancreatic adenocarcinoma is limited because this malignancy remains resistant to most chemotherapeutic drugs. Strategies that reverse epigenetic alterations offer a unique opportunity for cancer cell reprogramming, which is valuable for development of new treatments. The aim of this work was to reprogram pancreatic ductal adenocarcinoma (PDAC) cells toward a less aggressive and drug-responsive phenotype. The process applied is called "epigenetic reprogramming". To evaluate the efficiency of PDAC epigenetic reprogramming, we assessed tumor growth and drug response in PANC-1 cells after exposure to non-cytotoxic doses of the demethylating agent 5-azacytidine (5-AZA). Here, we showed that an epigenetic regimen using 5-AZA promoted an anti-cancer response by inhibiting PDAC tumor growth in vivo after the engraftment of treated cells. Remarkably, the subsequent addition of gemcitabine (GEM) to the 5-AZA-mediated reprogramming resulted in a marked growth inhibition effect in GEM-resistant pancreatic cancer cells. We observed that various characteristic peptides expressed in the pancreas, which included the antiproliferative hormone somatostatin (SST) and the SST receptor 2 (SSTR2), were significantly upregulated in the epigenetically reprogrammed PDAC cells. The inhibitory effect of octreotide (OCT), an SST analog, was tested on PDAC cells and found to be improved after cell reprogramming. Furthermore, we found that SST gene expression restoration following 5-AZA treatment or following knockdown of the DNA methyltransferase (DNMT) 1 enzyme was associated with the reversion of SST epigenetic silencing through regional CpG demethylation. Lastly, we confirmed the efficacy of 5-AZA-based epigenetic reprogramming in vivo using a PDAC tumor growth model. In conclusion, this study demonstrates that epigenetic reprogramming using the demethylating compound 5-AZA shows anti-cancer effects in PANC-1 cells and is potentially attractive for the treatment of solid tumors.

DNA methylation in the tumor microenvironment

The tumor microenvironment (TME) plays an important role in supporting cancer progression. The TME is composed of tumor cells, the surrounding tumor-associated stromal cells, and the extracellular matrix (ECM). Crosstalk between the TME components contributes to tumorigenesis. Recently, one of our studies showed that pancreatic ductal adenocarcinoma (PDAC) cells can induce DNA methylation in cancer-associated fibroblasts (CAFs), thereby modifying tumor-stromal interactions in the TME, and subsequently creating a TME that supports tumor growth. Here we summarize recent studies about how DNA methylation affects tumorigenesis through regulating tumor-associated stromal components including fibroblasts and immune cells. We also discuss the potential for targeting DNA methylation for the treatment of cancers.

The effect of metformin on survival of patients with pancreatic cancer: a meta-analysis

We conducted a meta-analysis to analyse the effect of metformin on survival of pancreatic cancer patients at various stages. We performed a systematic search of PubMed, Embase, Cochrane, and Web of Science to identify all relevant studies. Summary hazard ratios (HR) of survival and 95% confidence intervals (95% CI) were calculated with a fixed or random effects model according to inter-study heterogeneity. Nine retrospective cohort studies and two randomized controlled trials (RCTs) were eligible. There was a significant improvement in survival (HR = 0.86, 95% CI 0.76–0.97; P < 0.05) in the metformin group compared with control. Subgroup analysis indicated that metformin improved survival in patients with resection (HR = 0.79, 95% CI 0.69–0.91; P < 0.05) and patients with locally advanced tumors (HR = 0.68, 95% CI 0.55–0.84; P < 0.05) but not in patients with metastatic tumors, even when RCT data were included (HR = 0.99, 95% CI 0.70–1.40; P > 0.05), or were excluded (HR = 0.89, 95% CI 0.61–1.31; P > 0.05). This meta-analysis indicated that the effect of metformin does correlate with tumor stage but should be prudently considered given the limited and variable studies performed to data.

Nutrients and the Pancreas: An Epigenetic Perspective

Pancreatic cancer is the fourth most common cause of cancer-related deaths with a dismal average five-year survival rate of six percent. Substitutional progress has been made in understanding how pancreatic cancer develops and progresses. Evidence is mounting which demonstrates that diet and nutrition are key factors in carcinogenesis. In particular, diets low in folate and high in fruits, vegetables, red/processed meat, and saturated fat have been identified as pancreatic cancer risk factors with a proposed mechanism involving epigenetic modifications or gene regulation. We review the current literature assessing the correlation between diet, epigenetics, and pancreatic cancer.

Pancreatic cancer actionable genes in precision medicine and personalized surgery

Pancreatic ductal adenocarcinoma (PDAC) is a deadly cancer with an overall 5-year survival rate less than 5% due to the poor early diagnosis and lack of effective therapeutic options. The most effective therapy remains surgery, however post-operative survival could be enhanced with effective adjuvant therapy. The massive information gained from Omics techniques on PDAC at the beginning of the 21st century is a remarkable accomplishment. However, the information gained from the omics data, including next generation sequencing data, has yet to successfully affect care of patients suffering with PDAC. Therefore, we propose the development of an actionable genomic platform that matches a patient's PDAC clinically actionable genes with potential targeted adjuvant therapies. Using this platform, PDX1 has been identified as a potential actionable gene for PDAC, therefore, RNAi therapy, gene therapy and small inhibitory drugs, all targeting PDX1, serve as potential targeted adjuvant therapies. Preclinical studies support the hypothesis that identification of PDAC actionable genes could permit translation of a patient's genomic information into precision targeted adjuvant therapy for PDAC.

Effect of evodiamine and berberine on the interaction between DNMTs and target microRNAs during malignant transformation of the colon by TGF-β1

The tissue microenvironment functions as a crucial player in carcinogenesis, and transforming growth factor-β1 (TGF-β1) within the microenvironment stimulates the formation of neoplasms. Using an in vitro model of malignancy induced by TGF-β1, we assessed the effect of evodiamine and berberine on the interaction between DNA methyltransferases (DNMTs) and target microRNAs (miRNAs) in the model. Colon tissues from neonatal rats 7 days of age were cultured and malignancy was induced by TGF-β1 in vitro for 48 h, and then the tissues were respectively treated with evodiamine and berberine for 24 h. Morphological alteration of tissues was observed by an inverted microscope, histological structures were observed using hematoxylin and eosin staining, and the expression levels of DNMTs and targeted miRNAs screened by bioinformatics software combined with Gene chip analysis in our previous study were detected by immunohistochemistry and quantified by real-time PCR. Twenty-four hours after treatment with TGF-β1, expression levels of DNMT1, DNMT3A, DNMT3B and miR-152 (target DNMT1), miR-429 (target DNMT3A) and miR-29a (target DNMT3A/3B) were markedly decreased; however, after 48 h, the expression levels of DNMT1 and DNMT3A were significantly increased, but their target miRNAs were still decreased. After treatment with a DNMT inhibitor (5-Aza-dC), expression levels of the miRNAs were increased to a larger extent, but did not reach normal levels. After treatment with berberine and evodiamine for 24 h, respectively, increased expression of DNMT1, DNMT3A, DNMT3B and miR-152, miR-429, miR-29a was noted. In conclusion, the results of the present study suggest that miRNAs can also be post-transcriptionally regulated by their corresponding DNMTs and that berberine and evodiamine regulate the expression of these genes, which provides early epigenetic evidence for the prevention and therapy of colorectal cancer.

Epigenetic control of the tumor microenvironment

Stromal cells of the tumor microenvironment have been shown to play important roles in both supporting and limiting cancer growth. The altered phenotype of tumor-associated stromal cells (fibroblasts, immune cells, endothelial cells etc.) is proposed to be mainly due to epigenetic dysregulation of gene expression; however, only limited studies have probed the roles of epigenetic mechanisms in the regulation of stromal cell function. We review recent studies demonstrating how specific epigenetic mechanisms (DNA methylation and histone post-translational modification-based gene expression regulation, and miRNA-mediated translational regulation) drive aspects of stromal cell phenotype, and discuss the implications of these findings for treatment of malignancies. We also summarize the effects of epigenetic mechanism-targeted drugs on stromal cells and discuss the consideration of the microenvironment response in attempts to use these drugs for cancer treatment.

Oncogenic Ras suppresses ING4-TDG-Fas axis to promote apoptosis resistance

Ras is aberrantly activated in many cancers and active DNA demethylation plays a fundamental role to establish DNA methylation pattern which is of importance to cancer development. However, it was unknown whether and how Ras regulate DNA demethylation during carcinogenesis. Here we found that Ras downregulated thymine-DNA glycosylase (TDG), a DNA demethylation enzyme, by inhibiting the interaction of transcription activator ING4 with TDG promoter. TDG recruited histone lysine demethylase JMJD3 to the Fas promoter and activated its expression, thus restoring sensitivity to apoptosis. TDG suppressed in vivo tumorigenicity of xenograft pancreatic cancer. Thus, we speculate that reversing Ras-mediated ING4 inhibition to activate Fas expression is a potential therapeutic approach for Ras-driven cancers.

Epigenetic therapy in gastrointestinal cancer: the right combination

Epigenetics is a relatively recent field of molecular biology that has arisen over the past 25 years. Cancer is now understood to be a disease of widespread epigenetic dysregulation that interacts extensively with underlying genetic mutations. The development of drugs targeting these processes has rapidly progressed; with several drugs already FDA approved as first-line therapy in hematological malignancies. Gastrointestinal (GI) cancers possess high degrees of epigenetic dysregulation, exemplified by subtypes such as CpG island methylator phenotype (CIMP), and the potential benefit of epigenetic therapy in these cancers is evident. The application of epigenetic drugs in solid tumors, including GI cancers, is just emerging, with increased understanding of the cancer epigenome. In this review, we provide a brief overview of cancer epigenetics and the epigenetic targets of therapy including deoxyribonucleic acid (DNA) methylation, histone modifications, and chromatin remodeling. We discuss the epigenetic drugs currently in use, with a focus on DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors, and explain the pharmacokinetic and mechanistic challenges in their application. We present the strategies employed in incorporating these drugs into the treatment of GI cancers, and explain the concept of the cancer stem cell in epigenetic reprogramming and reversal of chemo resistance. We discuss the most promising combination strategies in GI cancers including: (1) epigenetic sensitization to radiotherapy, (2) epigenetic sensitization to cytotoxic chemotherapy, and (3) epigenetic immune modulation and priming for immune therapy. Finally, we present preclinical and clinical trial data employing these strategies thus far in various GI cancers including colorectal, esophageal, gastric, and pancreatic cancer.

Molecular therapeutics in pancreas cancer

The emergence of the "precision-medicine" paradigm in oncology has ushered in tremendous improvements in patient outcomes in a wide variety of malignancies. However, pancreas ductal adenocarcinoma (PDAC) has remained an obstinate challenge to the oncology community and continues to be associated with a dismal prognosis with 5-year survival rates consistently less than 5%. Cytotoxic chemotherapy with gemcitabine-based regimens has been the cornerstone of treatment in PDAC especially because most patients present with inoperable disease. But in recent years remarkable basic science research has improved our understanding of the molecular and genetic basis of PDAC. Whole genomic analysis has exemplified the genetic heterogeneity of pancreas cancer and has led to ingenious efforts to target oncogenes and their downstream signaling cascades. Novel stromal depletion strategies have been devised based on our enhanced recognition of the complex architecture of the tumor stroma and the various mechanisms in the tumor microenvironment that sustain tumorigenesis. Immunotherapy using vaccines and immune checkpoint inhibitors has also risen to the forefront of therapeutic strategies against PDAC. Furthermore, adoptive T cell transfer and strategies to target epigenetic regulators are being explored with enthusiasm. This review will focus on the recent advances in molecularly targeted therapies in PDAC and offer future perspectives to tackle this lethal disease.

Cep70 overexpression stimulates pancreatic cancer by inducing centrosome abnormality and microtubule disorganization

The centrosome is crucial for mitotic fidelity, and centrosome aberrations are associated with genomic instability and tumorigenesis. The centrosomal protein Cep70 has been reported to play a role in various cellular activities. However, whether this protein is involved in pathological processes remains unknown. In this study, we demonstrate that Cep70 is highly expressed in pancreatic cancer tissues. Cep70 expression correlates with clinicopathological parameters of pancreatic cancer, including histological grade, pathological tumor node metastasis stage, lymph node metastasis, and carbohydrate antigen 19-9 level. Depletion of Cep70 significantly suppresses pancreatic cancer cell proliferation and promotes apoptotic cell death, and exogenous expression of Cep70 can rescue the above effects. Cep70 also stimulates colony formation in soft agar and enhances tumor growth in mice. Our data further show that ectopic expression of Cep70 in pancreatic cancer cells results in the mislocalization of centrosomal proteins, including γ-tubulin and pericentrin, and the formation of intracellular aggregates. In addition, Cep70 overexpression leads to microtubule disorganization and the formation of multipolar spindles during mitosis. Our study thus unravels a critical role for Cep70 in pancreatic cancer and suggests Cep70 as a potential biomarker and therapeutic target for this deadly disease.

Epigenetic therapy for solid tumors: from bench science to clinical trials

The cancer epigenome is characterized by global DNA methylation and chromatin changes, such as the hypermethylation of specific CpG island promoters. Epigenetic agents like DNA methyltransferase or histone deacetylase inhibitors induce phenotype changes by reactivation of epigenetically silenced tumor suppressor genes. Despite initial promise in hematologic malignancies, epigenetic agents have not shown significant efficacy as monotherapy against solid tumors. Recent trials showed that epigenetic agents exert favorable modifier effects when combined with chemotherapy, hormonal therapy, or other epigenetic agents. Due to the novel nature of their mechanism, it is important to reconsider the optimal patient selection, drug regimen, study design, and outcome measures when pursuing future trials in order to discover the full potential of this new therapeutic modality.

Clinicopathological Significance of CDKN2A Promoter Hypermethylation Frequency with Pancreatic Cancer

The prognosis of pancreatic cancer patients is very poor, with a 5-year survival of less than 6%. Previous studies demonstrated that the loss of function of CDKN2A is mainly caused by the hypermethylation of CDKN2A gene promoter; however, whether or not it is associated with the incidence of pancreatic cancer still remains unclear. In this study, we systematically reviewed the association between CDKN2A promoter methylation and pancreatic cancer using meta-analysis methods. The pooled data were analyzed by Review Manager 5.2. Fourteen studies eligible studies, including 418 pancreatic cancer, 155 pancreatic intraepithelial neoplasia (PanINs) and 45 chronic pancreatitis (CP) patients were analyzed. We observed that the frequency of CDKN2A methylation was significantly higher in pancreatic cancer patients than in normal healthy controls, the pooled OR = 17.19, 95% CI = 8.72–33.86, P < 0.00001. The frequency of CDKN2A methylation was also significantly higher in PanINs patients than that in normal individual controls, OR = 12.35, 95% CI = 1.70–89.89, P = 0.01. In addition, CDKN2A methylation was associated with worse survival in pancreatic cancer, HR = 4.46, 95% CI = 1.37–14.53, P = 0.01. The results strongly suggest that CDKN2A methylation is correlated with an increased risk of pancreatic cancer. CDKN2A methylation plays a critical role in pancreatic carcinogenesis and may serve as a prognostic marker.