Epigenetic therapy inhibits metastases by disrupting premetastatic niches.

Cancer recurrence after surgery remains an unresolved clinical problem1-3. Myeloid cells derived from bone marrow contribute to the formation of the premetastatic microenvironment, which is required for disseminating tumour cells to engraft distant sites4-6. There are currently no effective interventions that prevent the formation of the premetastatic microenvironment6,7. Here we show that, after surgical removal of primary lung, breast and oesophageal cancers, low-dose adjuvant epigenetic therapy disrupts the premetastatic microenvironment and inhibits both the formation and growth of lung metastases through its selective effect on myeloid-derived suppressor cells (MDSCs). In mouse models of pulmonary metastases, MDSCs are key factors in the formation of the premetastatic microenvironment after resection of primary tumours. Adjuvant epigenetic therapy that uses low-dose DNA methyltransferase and histone deacetylase inhibitors, 5-azacytidine and entinostat, disrupts the premetastatic niche by inhibiting the trafficking of MDSCs through the downregulation of CCR2 and CXCR2, and by promoting MDSC differentiation into a more-interstitial macrophage-like phenotype. A decreased accumulation of MDSCs in the premetastatic lung produces longer periods of disease-free survival and increased overall survival, compared with chemotherapy. Our data demonstrate that, even after removal of the primary tumour, MDSCs contribute to the development of premetastatic niches and settlement of residual tumour cells. A combination of low-dose adjuvant epigenetic modifiers that disrupts this premetastatic microenvironment and inhibits metastases may permit an adjuvant approach to cancer therapy.

A MULTI-HIT MODEL OF LONG COVID PATHOPHYSIOLOGY: THE INTERACTION BETWEEN IMMUNE TRIGGERS AND NERVOUS SYSTEM SIGNALING.

Early in the pandemic, clinicians recognized an overlap between Long COVID symptoms and dysautonomia, suggesting autonomic nervous system (ANS) dysfunction. Our clinical experience at Johns Hopkins with primary dysautonomia suggested heritability of sympathetic dysfunction, manifesting primarily as hyperhidrosis and as other dysautonomia symptoms. Whole exome sequencing revealed mutations in genes regulating electrical signaling in the nervous system, thus providing a genetic basis for the sympathetic overdrive observed. We hypothesize that dysautonomia in Long COVID requires two molecular hits: a genetic vulnerability to prime the ANS and a SARS-CoV-2 infection, as an immune trigger, to further disrupt ANS function resulting in increased sympathetic activity. Indeed, Long COVID patients show signs of chronic inflammation and autoimmunity. We have translated this two-hit concept to the clinic using ion channel inhibitors to target genetic susceptibility and immunomodulators to treat inflammation. This multi-hit hypothesis shows promise for managing Long COVID and merits further study.

Anxiety and dysautonomia symptoms in patients with a NaV1.7 mutation and the potential benefits of low-dose short-acting guanfacine.

PURPOSE: Guanfacine is an α2A-adrenergic receptor agonist, FDA-approved to treat attention-deficit hyperactivity disorder and high blood pressure, typically as an extended-release formulation up to 7 mg/day. In our dysautonomia clinic, we observed that off-label use of short-acting guanfacine at 1 mg/day facilitated symptom relief in two families with multiple members presenting with severe generalized anxiety. We also noted anecdotal improvements in associated dysautonomia symptoms such as hyperhidrosis, cognitive impairment, and palpitations. We postulated that a genetic deficit existed in these patients that might augment guanfacine susceptibility. METHODS: We used whole-exome sequencing to identify mutations in patients with shared generalized anxiety and dysautonomia symptoms. Guanfacine-induced changes in the function of voltage-gated Na+ channels were investigated using voltage-clamp electrophysiology. RESULTS: Whole-exome sequencing uncovered the p.I739V mutation in SCN9A in the proband of two nonrelated families. Moreover, guanfacine inhibited ionic currents evoked by wild-type and mutant NaV1.7 encoded by SCN9A, as well as other NaV channel subtypes to a varying degree. CONCLUSION: Our study provides further evidence for a possible pathophysiological role of NaV1.7 in anxiety and dysautonomia. Combined with off-target effects on NaV channel function, daily administration of 1 mg short-acting guanfacine may be sufficient to normalize NaV channel mutation-induced changes in sympathetic activity, perhaps aided by partial inhibition of NaV1.7 or other channel subtypes. In a broader context, expanding genetic and functional data about ion channel aberrations may enable the prospect of stratifying patients in which mutation-induced increased sympathetic tone normalization by guanfacine can support treatment strategies for anxiety and dysautonomia symptoms.

Gasdermin D represses inflammation-induced colon cancer development by regulating apoptosis.

Chronic inflammation is widely recognized as a major risk factor for cancer formation, but the underlying mechanisms are poorly understood. Recently, it was shown that Gasdermin D (GSDMD) protein drives pyroptotic cell death in macrophages on cleavage by inflammatory caspases. Even though the Gsdmd gene is specifically expressed in the intestinal epithelium, the role of Gsdmd in the intestinal tissues remains poorly characterized. In this study, we examined the biological role of Gsdmd in colorectal cancer (CRC) development, employing an azoxymethane/dextran sulfate sodium carcinogenesis model. Results show that GSDMD deficiency enhances CRC development, probably due to decreased apoptosis caused by downregulation of interferon-gamma (IFNγ)-signal transducer and activator 1 (STAT1) signaling. Furthermore, we show that GSDMD protein is diminished in human colorectal cancer, indicating involvement of GSDMD in repression of CRC development in humans. Our findings provide a new insight into functions of Gsdmd/GSDMD in colonic inflammation and human CRC development.

pfeRNAs-A Novel Class of Small Non-coding RNAs With Real Translational Potential.

Small non-coding RNAs (sncRNAs) are defined by being less than 200 nucleotides (nt) in length, and consequently, have been divided into many different subclasses including mature microRNA (miRNA), small interfering RNA (siRNA), piwi-interacting RNA (piRNA), protein functional effector sncRNA (pfeRNA), precursor miRNA (pre-miRNA), small nucleolar RNA (snoRNA), 5S ribosome RNA (5SrRNA), 5.8SrRNA, and small nuclear RNA (snRNA). Except for the class of pfeRNAs, the discovery, identification, biogenesis, characterization, and function of other sncRNAs have been well documented. Herein, we provide a review, written especially for clinicians, of the least understood class of functional sncRNAs, the pfeRNAs, focusing on their initial discovery, identification, unique features, function, as well as their exciting clinical translational potential.

Double stapling technique versus hemi-double stapling technique for esophagojejunostomy with OrVil™ after laparoscopic total gastrectomy: a single-blind, randomized clinical trial.

BACKGROUND: The transorally inserted anvil (OrVil™) is frequently selected for esophagojejunostomy after laparoscopic total gastrectomy (LTG) because of its versatility. During anastomosis with OrVil™, the double stapling technique (DST) or hemi-double stapling technique (HDST) can be selected by overlapping the linear stapler and the circular stapler. However, no studies have reported the differences between the methods and their clinical significance. METHODS: A randomized controlled clinical trial with a parallel assignment and single-blind outcomes assessment analysis was conducted. Patients with gastric cancer eligible for LTG who met the selection criteria were randomized. Preoperative characteristics and perioperative and postoperative outcomes were compared between the DST and HDST. The primary endpoint was an anastomosis-related complication, and the secondary endpoints were perioperative outcomes and postoperative complications, excluding anastomosis-related complications. RESULTS: Thirty patients with gastric cancer were eligible and randomized. LTG and esophagojejunostomy were successfully performed in all patients, without conversion to laparotomy. Preoperative characteristics, excluding preoperative chemotherapy, were not significantly different between the two groups. One anastomotic leakage of Clavien-Dindo classification grade ≥ IIIa was observed in the DST, although no significant difference was found between the two groups (6.6% vs. 0%, P = 0.30). In the HDST, one case of anastomotic stricture required endoscopic balloon dilation. No significant differences were found in operative time, whereas the anastomosis time was significantly shorter in the HDST than in the DST (47.5 ± 15.8 vs. 38.2 ± 8.8 min, P = 0.028). Except for anastomosis-related complications, postoperative complications (P = 0.282) and postoperative hospital stay for the DST and HDST were not significantly different. CONCLUSIONS: No superiority was found between the DST and HDST with OrVil™ in esophagojejunostomy of LTG for gastric cancer with respect to postoperative complications, whereas the HDST may be preferable in terms of the simplicity of the surgical technique.

Prenatal stress enhances atherosclerosis and telomere shortening in ApoE knockout mouse offspring.

Children born to women who experience stress during pregnancy have an increased risk of atherosclerosis in later life, but few animal models have explored mechanisms. To study this phenomenon, timed-bred ApoE knockout mice were determined pregnant with ultrasound and randomly assigned on gestation day 8.5 to either a control (no stress) or prenatal stress (PS) group using 2 h of restraint for five consecutive days. PS significantly increased plasma corticosterone levels in pregnant mice. The litters from PS mice showed increased neonatal mortality within the first week of life. Body weights (at euthanasia) of adult offspring at 25 wk from the PS group were significantly increased compared with weights of controls. Adult offspring from these pregnancies were serially imaged with ultrasound to measure plaque thickness and were compared with plaque macroscopic and microscopic pathology. PS groups had increased plaque thickness determined by ultrasound, gross, histological evaluation and increased aortic root and valve macrophage infiltration at 25 wk. Five-week-old mice from PS group had significant decrease in mean arterial pressure, yet blood pressure normalized by 10 wk. As prenatal stress induced increased atherosclerosis, and telomeres are susceptible to stress, aortas from 10-wk-old mice were compared for telomere lengths and were found to be significantly shorter in PS mice compared with control mice. These studies support future investigation of how stress impacts telomere shortening in animal models and human aortas. This model could be further used to investigate the role of prenatal stress, telomere biology, and atherosclerosis pathogenesis in adults.

Disparities in Surgical Oncology: Management of Advanced Cancer.

Significant variations in the patterns of care, incidence, and mortality rates of several common cancers have been noted. These disparities have been attributed to a complex interplay of factors, including genetic, environmental, and healthcare-related components. Within this review, primarily focusing on commonly occurring cancers (breast, lung, colorectal), we initially summarize the burden of these disparities with regard to incidence and screening patterns. We then explore the interaction between several proven genetic, epigenetic, and environmental influences that are known to contribute to these disparities.

Prenatal stress enhances NNK-induced lung tumors in A/J mice.

Children born to women who experience stress during pregnancy have an increased risk of cancer in later life, but no previous animal studies have tested such a link. We questioned whether prenatal stress (PS) in A/J mice affected the development of lung tumors after postnatal response to tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Timed-bred A/J mice were randomly assigned on gestation day 12.5 to PS by restraint for 5 consecutive days or control (no restraint). Adult offspring of control and stressed pregnancies were all treated with three NNK injections (50 mg/kg every other day) and euthanized 16 weeks later to examine their lungs. Compared with controls, PS dams exhibited significantly increased levels of plasma corticosterone, increased adrenal weights and decreased fetus weights without fetal loss. Prenatally stressed litters had a significantly higher neonatal death rate within first week of life, and surviving male and female offspring developed lung epithelial proliferations with increase multiplicity, increased area and aggressive morphology. PS also induced more advanced atypical adenomatous hyperplasia lesions. We found no difference in lung NNK-derived methyl DNA adducts, but PS did significantly enhance CD3+ T cell and Foxp3+ T cell tumor infiltration. PS significantly increases multiplicity, area of NNK-induced lung tumors and advanced morphology. PS did not affect production of NNK-derived methyl DNA adducts but did increase lymphocytic infiltration of lung tumors. To our knowledge, this is the first animal model of PS with evaluation of cancer development in offspring.

Prognostic Impact of Phosphorylated Discoidin Domain Receptor-1 in Esophageal Cancer.

BACKGROUND: Esophageal squamous cell carcinoma (ESCC) is common in East Asia and also is often deadly. We sought to determine whether measuring the discoidin domain receptor-1 (DDR1)-both total and phosphorylated proteins-could improve our ability to predict recurrence in ESCC. MATERIALS AND METHODS: Total DDR1 and phosphorylated DDR1 (pDDR1) were measured using semiquantitative immunohistochemistry in a cohort of 60 patients with ESCC. Association between these immunohistochemical measurements and standard clinical-pathological variables such as patient recurrence-free survival was examined using univariate and multivariate analyses. RESULTS: Six patients (10.0%) had regional recurrence and eight patients (13.3%) had distant recurrence. In univariate analysis, early disease recurrence correlated with intense staining of total DDR1 (P = 0.03) as well as intense staining of pDDR1 (P < 0.001). On multivariate analysis, only regional lymph node metastasis (P = 0.04, HR = 4.20) and intensity of pDDR1 immunohistochemistry (P = 0.03, HR = 4.27) emerged as significant independent prognostic factors for recurrence. CONCLUSIONS: This study suggests that immunohistochemical measurements of both the DDR1 protein and pDDR1 can provide prognostic value in ESCC, even when other clinical and pathological factors are also being considered.

DNA methylation genome-wide analysis in remnant and primary gastric cancers.

BACKGROUND: Although primary (PGC) and remnant gastric cancers (RGC) both originate from the same gastrointestinal organ, they have very distinct clinicopathological behaviors. We hypothesized that there would be distinct differences in DNA methylation patterns that would occur during carcinogenesis of RGC and PGC, and that the differences in methylation patterns may help identify the primary factor contributing to chronic inflammation in patients with RGC. METHODS: We investigated the genome-wide DNA methylation patterns of PGC and RGC tissues from 48 patients using the Infinium HumanMethylation450 Beadchip assay. The results were validated by quantitative methylation-specific PCR (qMSP) in separate, independent cohorts. RESULTS: We found that in our training cohort of 48 patients, the most variable genes from the gastric cancer tissues identified by the Infinium HumanMethylation450 Beadchip clustered the resultant heatmap into high and low methylation groups. On multivariate analysis, PGCs contributed significantly to the high methylation group (p = 0.004, OR 12.33), which suggested that the promoter methylation status in PGC is higher than that in RGC. Supporting this conclusion was the finding that in a separate qMSP analysis in a test cohort, the EPB41L3 gene, chosen because of its high ß value on microarray analysis in the gastric cancer tissues, had significantly higher DNA promoter methylation in cancer tissues in the validation PGC tissues than in RGC. CONCLUSIONS: This study demonstrated that promoter methylation status in PGC is higher than in RGC. This result may reflect the effects of the absence of Helicobacter pylori on the reduced DNA methylation in the remnant stomach.

Phase Ib/II study of safety and efficacy of low-dose decitabine-primed chemoimmunotherapy in patients with drug-resistant relapsed/refractory alimentary tract cancer.

The pressing need for improved therapeutic outcomes provides a good rationale for identifying effective strategies for alimentary tract (AT) cancer treatment. The potential re-sensitivity property to chemo- and immunotherapy of low-dose decitabine has been evident both preclinically and in previous phase I trials. We conducted a phase Ib/II trial evaluating low-dose decitabine-primed chemoimmunotherapy in patients with drug-resistant relapsed/refractory (R/R) esophageal, gastric or colorectal cancers. Forty-five patients received either the 5-day decitabine treatment with subsequent readministration of the previously resistant chemotherapy (decitabine-primed chemotherapy, D-C cohort) or the aforementioned regimen followed by cytokine-induced killer cells therapy (D-C and cytokine-induced killer [CIK] cell treatment, D-C + CIK cohort) based on their treatment history. Grade 3 to 4 adverse events (AEs) were reported in 11 (24.4%) of 45 patients. All AEs were controllable, and no patient experienced a treatment-related death. The objective response rate (ORR) and disease control rate (DCR) were 24.44% and 82.22%, respectively, including two patients who achieved durable complete responses. Clinical response could be associated with treatment-free interval and initial surgical resection history. ORR and DCR reached 28% and 92%, respectively, in the D-C + CIK cohort. Consistently, the progression-free survival (PFS) of the D-C + CIK cohort compared favorably to the best PFS of the pre-resistant unprimed therapy (p = 0.0001). The toxicity and ORRs exhibited were non-significantly different between cancer types and treatment cohort. The safety and efficacy of decitabine-primed re-sensitization to chemoimmunotherapy is attractive and promising. These data warrant further large-scale evaluation of drug-resistant R/R AT cancer patients with advanced stage disease.

DREAMing: a simple and ultrasensitive method for assessing intratumor epigenetic heterogeneity directly from liquid biopsies.

Many cancers comprise heterogeneous populations of cells at primary and metastatic sites throughout the body. The presence or emergence of distinct subclones with drug-resistant genetic and epigenetic phenotypes within these populations can greatly complicate therapeutic intervention. Liquid biopsies of peripheral blood from cancer patients have been suggested as an ideal means of sampling intratumor genetic and epigenetic heterogeneity for diagnostics, monitoring and therapeutic guidance. However, current molecular diagnostic and sequencing methods are not well suited to the routine assessment of epigenetic heterogeneity in difficult samples such as liquid biopsies that contain intrinsically low fractional concentrations of circulating tumor DNA (ctDNA) and rare epigenetic subclonal populations. Here we report an alternative approach, deemed DREAMing (Discrimination of Rare EpiAlleles by Melt), which uses semi-limiting dilution and precise melt curve analysis to distinguish and enumerate individual copies of epiallelic species at single-CpG-site resolution in fractions as low as 0.005%, providing facile and inexpensive ultrasensitive assessment of locus-specific epigenetic heterogeneity directly from liquid biopsies. The technique is demonstrated here for the evaluation of epigenetic heterogeneity at p14(ARF) and BRCA1 gene-promoter loci in liquid biopsies obtained from patients in association with non-small cell lung cancer (NSCLC) and myelodysplastic/myeloproliferative neoplasms (MDS/MPN), respectively.

Predictive value of CHFR and MLH1 methylation in human gastric cancer.

BACKGROUND: Gastric carcinoma (GC) has one of the highest mortality rates of cancer diseases and has a high incidence rate in China. Palliative chemotherapy is the main treatment for advanced gastric cancer. It is necessary to compare the effectiveness and toxicities of different regimens. This study explores the possibility of methylation of DNA damage repair genes serving as a prognostic and chemo-sensitive marker in human gastric cancer. METHODS: The methylation status of five DNA damage repair genes (CHFR, FANCF, MGMT, MLH1, and RASSF1A) was detected by nested methylation-specific PCR in 102 paraffin-embedded gastric cancer samples. Chi-square or Fisher's exact tests were used to evaluate the association of methylation status and clinic-pathological factors. The Kaplan-Meier method and Cox proportional hazards models were employed to analyze the association of methylation status and chemo-sensitivity. RESULTS: The results indicate that CHFR, MLH1, RASSF1A, MGMT, and FANCF were methylated in 34.3% (35/102), 21.6% (22/102), 12.7% (13/102), 9.8% (10/102), and 0% (0/102) of samples, respectively. No association was found between methylation of CHFR, MLH1, RASSF1A, MGMT, or FANCF with gender, age, tumor size, tumor differentiation, lymph node metastasis, and TNM stage. In docetaxel-treated gastric cancer patients, resistance to docetaxel was found in CHFR unmethylated patients by Cox proportional hazards model (HR 0.243, 95% CI, 0.069-0.859, p = 0.028), and overall survival is longer in the CHFR methylated group compared with the CHFR unmethylated group (log-rank, p = 0.036). In oxaliplatin-treated gastric cancer patients, resistance to oxaliplatin was found in MLH1 methylated patients (HR 2.988, 95% CI, 1.064-8.394, p = 0.038), and overall survival was longer in the MLH1 unmethylated group compared with the MLH1 methylated group (log-rank, p = 0.046). CONCLUSIONS: CHFR is frequently methylated in human gastric cancer, and CHFR methylation may serve as a docetaxel-sensitive marker. MLH1 methylation was related to oxaliplatin resistance in gastric cancer patients.

Epigenetic silencing of DACH1 induces the invasion and metastasis of gastric cancer by activating TGF-ß signalling.

Gastric cancer (GC) is the fourth most common malignancy in males and the fifth most common malignancy in females worldwide. DACH1 is frequently methylated in hepatic and colorectal cancer. To further understand the regulation and mechanism of DACH1 in GC, eight GC cell lines, eight cases of normal gastric mucosa, 98 cases of primary GC and 50 cases of adjacent non-tumour tissues were examined. Methylation-specific PCR, western blot, transwell assay and xenograft mice were used in this study. Loss of DACH1 expression correlated with promoter region methylation in GC cells, and re-expression was induced by 5-Aza-2'-deoxyazacytidine. DACH1 is methylated in 63.3% (62/98) of primary GC and 38% (19/50) of adjacent non-tumour tissues, while no methylation was found in normal gastric mucosa. Methylation of DACH1 correlated with reduced expression of DACH1 (P < 0.01), late tumour stage (stage III/IV) (P < 0.01) and lymph node metastasis (P < 0.05). DACH1 expression inhibited epithelial-mesenchymal transition and metastasis by inhibiting transforming growth factor (TGF)-ß signalling and suppressed GC cell proliferation through inducing G2/M phase arrest. The tumour size is smaller in DACH1-expressed BGC823 cell xenograft mice than in unexpressed group (P < 0.01). Restoration of DACH1 expression also sensitized GC cells to docetaxel. These studies suggest that DACH1 is frequently methylated in human GC and expression of DACH1 was controlled by promoter region methylation. DACH1 suppresses GC proliferation, invasion and metastasis by inhibiting TGF-ß signalling pathways both in vitro and in vivo. Epigenetic silencing DACH1 may induce GC cells' resistance to docetaxel.

Epigenetic regulation of DACT2, a key component of the Wnt signalling pathway in human lung cancer.

Dapper, Dishevelled-associated antagonist of ß-catenin (DACT), is involved in Xenopus embryonic development. Human DACT2 is localized on chromosome 6q27, a region of frequent loss of heterozygosity (LOH) in human cancers. However, the function and regulation of DACT2 in human lung cancer remain unclear. DNA sequencing, methylation-specific PCR (MSP), semi-quantitative RT-PCR, western blotting, and xenograft models were employed in this study. Eight lung cancer cell lines, 106 cases of primary lung cancer, four specimens of normal lung from patients without cancer, and 99 blood samples from healthy individuals were examined. We found that while there was no SNP related to lung cancer, the DACT2 promoter region is frequently methylated in human lung cancer. DACT2 is silenced by promoter region hypermethylation and re-expressed by 5-aza-2'-deoxyazacytidine treatment of lung cancer cell lines. Methylation of DACT2 was associated with poor differentiation of lung cancer. Loss of DACT2 expression was associated with promoter region hypermethylation in primary lung cancer, and was associated with increased ß-catenin expression. Restoration of DACT2 expression suppressed tumour proliferation both in vitro and in vivo. DACT2 expression was down-regulated by siRNA knockdown in H727 cells. DACT2 inhibited T-cell factor/lymphoid enhancer factor (TCF/LEF) and its downstream genes. In conclusion, DACT2 methylation is a potential lung cancer detection marker. DACT2 is regulated by promoter region hypermethylation. DACT2 inhibits lung cancer proliferation by suppressing the Wnt signalling pathway in lung cancer.

Impact of the Aboral Pouch in Roux-en-Y Reconstruction after Laparoscopic Total Gastrectomy for Elderly Patients.

Objectives: The number of elderly people with stomach cancer is increasing; therefore, minimally invasive surgical treatments are required. Elderly patients have multiple comorbidities and are prone to postoperative weight loss, nutritional disorders, Postgastrectomy syndrome (PGS), and decreased quality of life (QOL). Total gastrectomy is particularly associated with these complications, although aboral-pouch creation reportedly improves the condition by compensating for lost reservoir capacity. However, there is no consensus regarding its significance. This study aimed to investigate the impact of the aboral pouch on total gastrectomy outcomes in elderly patients. Materials and Methods: Thirty-six patients who met the eligibility criteria, defined as elderly patients aged ≥75 years, were retrospectively analyzed. The patients had undergone Roux-en-Y reconstructions with an aboral pouch in laparoscopic total gastrectomy procedures performed at Juntendo University from July 2016 to June 2022. The main outcomes were postoperative nutritional status, PGS, and QOL. Results: The average postoperative period was approximately 1 year (12.0 vs. 13.5 months, P=0.536), for 14 elderly and 22 non-elderly patients, respectively. Elderly patients had more comorbidities (78.5% vs. 40.9%, P=0.041). The outcome of nutritional status demonstrated no differences in weight-loss rate (-5.3% vs. -8.6%, P=0.651) or prognostic nutritional status (-7.9% vs. -5.9%, P=0.243). There was no significant difference in PGS and QOL between elderly and non-elderly patients. Conclusions: Total gastrectomy with an aboral-pouch creation could be beneficial for elderly 43 patients from the perspective of postoperative nutritional status, PGS, and QOL.

Epigenetic silencing of BEND4, a novel DNA damage repair gene, is a synthetic lethal marker for ATM inhibitor in pancreatic cancer.

Synthetic lethality is a novel model for cancer therapy. To understand the function and mechanism of BEN domain-containing protein 4 (BEND4) in pancreatic cancer, eight cell lines and a total of 492 cases of pancreatic neoplasia samples were included in this study. Methylation-specific polymerase chain reaction, CRISPR/Cas9, immunoprecipitation assay, comet assay, and xenograft mouse model were used. BEND4 is a new member of the BEN domain family. The expression of BEND4 is regulated by promoter region methylation. It is methylated in 58.1% (176/303) of pancreatic ductal adenocarcinoma (PDAC), 33.3% (14/42) of intraductal papillary mucinous neoplasm, 31.0% (13/42) of pancreatic neuroendocrine tumor, 14.3% (3/21) of mucinous cystic neoplasm, 4.3% (2/47) of solid pseudopapillary neoplasm, and 2.7% (1/37) of serous cystic neoplasm. BEND4 methylation is significantly associated with late-onset PDAC (> 50 years, P < 0.01) and tumor differentiation (P < 0.0001), and methylation of BEND4 is an independent poor prognostic marker (P < 0.01) in PDAC. Furthermore, BEND4 plays tumor-suppressive roles in vitro and in vivo. Mechanistically, BEND4 involves non-homologous end joining signaling by interacting with Ku80 and promotes DNA damage repair. Loss of BEND4 increased the sensitivity of PDAC cells to ATM inhibitor. Collectively, the present study revealed an uncharacterized tumor suppressor BEND4 and indicated that methylation of BEND4 may serve as a potential synthetic lethal marker for ATM inhibitor in PDAC treatment.

Invited commentary: the etiology of lung cancer in men compared with women.

Lung cancer is the leading cause of cancer death among women in the United States and other Western nations. The predominant cause of lung cancer in women is active cigarette smoking. Secondhand exposure to tobacco smoke is another important cause. The hypothesis that women are more susceptible than men to smoking-induced lung cancer has not been supported by the preponderance of current data, as noted by De Matteis et al. (Am J Epidemiol. 2013;177(7):601-612) in the accompanying article. However, aspects of lung cancer in men and women continue to indicate potential male-female differences in the etiology of lung cancer, based on several observations: 1) among never smokers, women have higher lung cancer incidence rates than men; 2) there is evidence that estrogen may contribute to lung cancer risk and progression; and 3) there are different clinical characteristics of lung cancer in women compared with men, such as the higher percentage of adenocarcinomas in never smokers, the greater prevalence of epidermal growth factor receptor gene (EGFR) mutations in adenocarcinomas among never smokers, and better prognosis. Considered in total, observations such as these offer enticing clues that, even amid cigarette smoking and other commonalities in the etiology of lung cancer in men and women, distinct differences may remain to be delineated that could potentially be of scientific and clinical relevance.