Bile acid and cigarette smoke enhance the aggressive phenotype of esophageal adenocarcinoma cells by downregulation of the mitochondrial uncoupling protein-2

Cigarette Smoke Enhances the Malignant Phenotype of Esophageal Adenocarcinoma Cells by Disrupting a Repressive Regulatory Interaction Between miR-145 and LOXL2

Although linked to esophageal carcinogenesis, the mechanisms by which cigarette smoke mediates initiation and progression of esophageal adenocarcinomas (EAC) have not been fully elucidated. In this study, immortalized esophageal epithelial cells and EAC cells (EACCs) were cultured with or without cigarette smoke condensate (CSC) under relevant exposure conditions. Endogenous levels of microRNA (miR)-145 and lysyl-likeoxidase 2 (LOXL2) were inversely correlated in EAC lines/tumors compared with that in immortalized cells/normal mucosa. The CSC repressed miR-145 and upregulated LOXL2 in immortalized esophageal epithelial cells and EACCs. Knockdown or constitutive overexpression of miR-145 activated or depleted LOXL2, respectively, which enhanced or reduced proliferation, invasion, and tumorigenicity of EACC, respectively. LOXL2 was identified as a novel target of miR-145 as well as a negative regulator of this miR in EAC lines/Barrett's epithelia. Mechanistically, CSC induced recruitment of SP1 to the LOXL2 promoter; LOXL2 upregulation coincided with LOXL2 enrichment and concomitant reduction of H3K4me3 levels within the promoter of miR143HG (host gene for miR-145). Mithramycin downregulated LOXL2 and restored miR-145 expression in EACC and abrogated LOXL2-mediated repression of miR-145 by CSC. These findings implicate cigarette smoke in the pathogenesis of EAC and demonstrate that oncogenic miR-145-LOXL2 axis dysregulation is potentially druggable for the treatment and possible prevention of these malignancies.

Conjugated Bile Acids Promote Lymphangiogenesis by Modulation of the Reactive Oxygen Species-p90RSK-Vascular Endothelial Growth Factor Receptor 3 Pathway

Conjugated bile acids (BA) are significantly elevated in several liver pathologies and in the metastatic lymph node (LN). However, the effects of BAs on pathological lymphangiogenesis remains unknown. The current study explores the effects of BAs on lymphangiogenesis. BA levels were elevated in the LN and serum of Mdr2-/- mice (model of sclerosing cholangitis) compared to control mice. Liver and LN tissue sections showed a clear expansion of the lymphatic network in Mdr2-/- mice, indicating activated lymphangiogenic pathways. Human lymphatic endothelial cells (LECs) expressed BA receptors and a direct treatment with conjugated BAs enhanced invasion, migration, and tube formation. BAs also altered the LEC metabolism and upregulated key metabolic genes. Further, BAs induced the production of reactive oxygen species (ROS), that in turn phosphorylated the redox-sensitive kinase p90RSK, an essential regulator of endothelial cell dysfunction and oxidative stress. Activated p90RSK increased the SUMOylation of the Prox1 transcription factor and enhanced VEGFR3 expression and 3-D LEC invasion. BA-induced ROS in the LECs, which led to increased levels of Yes-associated protein (YAP), a lymphangiogenesis regulator. The suppression of cellular YAP inhibited BA-induced VEGFR3 upregulation and lymphangiogenic mechanism. Overall, our data shows the expansion of the lymphatic network in presclerotic liver disease and establishes a novel mechanism whereby BAs promote lymphangiogenesis.

The role of bile acids in carcinogenesis

Bile acids are soluble derivatives of cholesterol produced in the liver that subsequently undergo bacterial transformation yielding a diverse array of metabolites. The bulk of bile acid synthesis takes place in the liver yielding primary bile acids; however, other tissues have also the capacity to generate bile acids (e.g. ovaries). Hepatic bile acids are then transported to bile and are subsequently released into the intestines. In the large intestine, a fraction of primary bile acids is converted to secondary bile acids by gut bacteria. The majority of the intestinal bile acids undergo reuptake and return to the liver. A small fraction of secondary and primary bile acids remains in the circulation and exert receptor-mediated and pure chemical effects (e.g. acidic bile in oesophageal cancer) on cancer cells. In this review, we assess how changes to bile acid biosynthesis, bile acid flux and local bile acid concentration modulate the behavior of different cancers. Here, we present in-depth the involvement of bile acids in oesophageal, gastric, hepatocellular, pancreatic, colorectal, breast, prostate, ovarian cancer. Previous studies often used bile acids in supraphysiological concentration, sometimes in concentrations 1000 times higher than the highest reported tissue or serum concentrations likely eliciting unspecific effects, a practice that we advocate against in this review. Furthermore, we show that, although bile acids were classically considered as pro-carcinogenic agents (e.g. oesophageal cancer), the dogma that switch, as lower concentrations of bile acids that correspond to their serum or tissue reference concentration possess anticancer activity in a subset of cancers. Differences in the response of cancers to bile acids lie in the differential expression of bile acid receptors between cancers (e.g. FXR vs. TGR5). UDCA, a bile acid that is sold as a generic medication against cholestasis or biliary surge, and its conjugates were identified with almost purely anticancer features suggesting a possibility for drug repurposing. Taken together, bile acids were considered as tumor inducers or tumor promoter molecules; nevertheless, in certain cancers, like breast cancer, bile acids in their reference concentrations may act as tumor suppressors suggesting a Janus-faced nature of bile acids in carcinogenesis.

Therapeutic Synergy in Esophageal Cancer and Mesothelioma Is Predicted by Dynamic BH3 Profiling

Approximately 20,000 patients per year are diagnosed with esophageal adenocarcinoma (EAC) and malignant pleural mesothelioma (MPM); fewer than 20% survive 5 years. Effective therapeutic strategies are limited although patients receive a combination of chemotherapeutics. These tumors harbor thousands of mutations that contribute to tumor development. Downstream of oncogenic driving mutations, altered tumor mitochondria promote resistance to apoptosis. Dynamic Bcl-2 homology-3 profiling (DBP) is a functional assay of live cells that identifies the mitochondrial proteins responsible for resistance to apoptosis. We hypothesized that DBP will predict which protein to target to overcome resistance thereby enhancing combinatorial therapy.DBP predicted that targeting either Mcl-1 or Bcl-xL increases the efficacy of the chemotherapeutic agent, cisplatin, whereas targeting Bcl-2 does not. We performed these assays by treating EAC and MPM cells with a combination of Bcl-2 homology-3 (BH3) mimetics and cisplatin. Following treatments, we performed efficacy assessments including apoptosis assays, IC₅₀ calculations, and generation of a combinatorial index. DBP confirmed that targeting mitochondria with BH3 mimetics alters the threshold of apoptosis. These apoptotic effects were abolished when the mitochondrial pathway was disrupted. We validated our findings by developing knockdown models of antiapoptotic proteins Mcl-1, Bcl-xL, and the mitochondrial effector proteins Bax/Bak. Knockdown of Mcl-1 or Bcl-xL recapitulated the results of BH3 mimetics. In addition, we report an approach for BH3 profiling directly from patient tumor samples. We demonstrate that the DBP assay on living tumor cells measures the dynamic changes of resistance mechanisms, assesses response to combinatorial therapy, and provides results in a clinically feasible time frame.

Mutation differences in circulating tumor DNAs from non-small cell lung cancer patients between Uygur and Han populations

BACKGROUND

The incidence of non-small cell lung cancer (NSCLC) in Uygur population is gradually increasing recently. In view of the great diagnostic and prognostic values of cell-free DNAs (cfDNA) detection, this study focus on a liquid biopsy to explore the value of cfDNA mutation in healthy and NSCLC patients in 2 ethnicities.

METHODS

The concentration and sequencing of cfDNA in NSCLC and healthy subjects was assessed with a standard information analysis procedure, including detection, annotation, and statistical analysis. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were conducted to analyze the function of mutant genes and related pathways. Totally, 133 subjects, including 35 Uygur NSCLC patients, 10 Uygur healthy subjects, 63 cases of Han NSCLC patients and 25 Han health control, were admitted to the hospital.

RESULTS

There were a lower proportion of adenocarcinoma and higher percentage of smoking rate for Uygur patients. For cfDNA level between NSCLC and healthy subjects, Han patients exhibited sharp increase while there was no statistical difference in Uygur population. In addition, the mutation frequency of cfDNA in Han patients (72.6%) was significantly higher than Uygur patients (45.7%). There were 5 gene mutations only found in Han patients and ABCC11 showed a higher mutation frequency in Uygur population as a common one. Finally, Go and Kyoto Encyclopedia of Genes and Genomes analysis showed apprent functional enrichments and pathway changes between 2 ethnicities.

CONCLUSION

There existed distinct distributions of cancer subtypes, smoking proportion, cfDNA level, and mutation patterns between Han and Uygur patients. The results may be a useful tool in NSCLC patients' diagnosis as well as individualized therapy between ethnicities in future.

A glycolysis-related gene signature predicts prognosis of patients with esophageal adenocarcinoma

Background: Esophageal adenocarcinoma (EAC) is a growing problem with a rapidly rising incidence and carries a poor prognosis. We aimed to develop a glycolysis-related gene signature to predict the prognostic outcome of patients with EAC.

Results: Five genes (CLDN9, GFPT1, HMMR, RARS and STMN1) were correlated with prognosis of EAC patients. Patients were classified into high-risk and low-risk groups calculated by Cox regression analysis, based on the five gene signature risk score. The five-gene signature was an independent biomarker for prognosis and patients with low risk scores showed better prognosis. Nomogram incorporating the gene signature and clinical prognostic factors was effective in predicting the overall survival.

Conclusion: An innovative identified glycolysis-related gene signature and an effective nomogram reliably predicted the prognosis of EAC patients.

Methods: The Cancer Genome Atlas database was investigated for the gene expression profile of EAC patients. Glycolytic gene sets difference between EAC and normal tissues were identified via Gene set enrichment analysis (GSEA). Univariate and multivariate Cox analysis were utilized to construct a prognostic gene signature. The signature was evaluated by receiver operating characteristic curves and Kaplan–Meier curves. A prognosis model integrating clinical parameters with the gene signature was established with nomogram.

Bile acid-induced "Minority MOMP" promotes esophageal carcinogenesis while maintaining apoptotic resistance via Mcl-1

Barrett's esophagus (BE) is associated with reflux and is implicated the development of esophageal adenocarcinoma (EAC). Apoptosis induces cell death through mitochondrial outer membrane permeabilization (MOMP), which is considered an irreversible step in apoptosis. Activation of MOMP to levels that fail to reach the apoptotic threshold may paradoxically promote cancer-a phenomenon called "Minority MOMP." We asked whether reflux-induced esophageal carcinogenesis occurred via minority MOMP and whether compensatory resistance mechanisms prevented cell death during this process. We exposed preneoplastic, hTERT-immortalized Barrett's cell, CP-C and CP-A, to the oncogenic bile acid, deoxycholic acid (DCA), for 1 year. Induction of minority MOMP was tested via comet assay, CyQuant, annexin V, JC-1, cytochrome C subcellular localization, caspase 3 activation, and immunoblots. We used bcl-2 homology domain-3 (BH3) profiling to test the mitochondrial apoptotic threshold. One-year exposure of Barrett's cells to DCA induced a malignant phenotype noted by clone and tumor formation. DCA promoted minority MOMP noted by minimal release of cytochrome C and limited caspase 3 activation, which resulted in DNA damage without apoptosis. Upregulation of the antiapoptotic protein, Mcl-1, ROS generation, and NF-κB activation occurred in conjunction with minority MOMP. Inhibition of ROS blocked minority MOMP and Mcl-1 upregulation. Knockdown of Mcl-1 shifted minority MOMP to complete MOMP as noted by dynamic BH3 profiling and increased apoptosis. Minority MOMP contributes to DCA induced carcinogenesis in preneoplastic BE. Mcl-1 provided a balance within the mitochondria that induced resistance complete MOMP and cell death. Targeting Mcl-1 may be a therapeutic strategy in EAC.

Chemoresistance to Cancer Treatment: Benzo-α-Pyrene as Friend or Foe?

Background: Environmental pollution such as exposure to pro-carcinogens including benzo-α-pyrene is becoming a major problem globally. Moreover, the effects of benzo-α-pyrene (BaP) on drug pharmacokinetics, pharmacodynamics, and drug resistance warrant further investigation, especially in cancer outpatient chemotherapy where exposure to environmental pollutants might occur. Method: We report here on the effects of benzo-α-pyrene on esophageal cancer cells in vitro, alone, or in combination with chemotherapeutic drugs cisplatin, 5-flurouracil, or paclitaxel. As the study endpoints, we employed expression of proteins involved in cell proliferation, drug metabolism, apoptosis, cell cycle analysis, colony formation, migration, and signaling cascades in the WHCO1 esophageal cancer cell line after 24 h of treatment. Results: Benzo-α-pyrene had no significant effect on WHCO1 cancer cell proliferation but reversed the effect of chemotherapeutic drugs by reducing drug-induced cell death and apoptosis by 30−40% compared to drug-treated cells. The three drugs significantly reduced WHCO1 cell migration by 40−50% compared to control and BaP-treated cells. Combined exposure to drugs was associated with significantly increased apoptosis and reduced colony formation. Evaluation of survival signaling cascades showed that although the MEK-ERK and Akt pathways were activated in the presence of drugs, BaP was a stronger activator of the MEK-ERK and Akt pathways than the drugs. Conclusion: The present study suggest that BaP can reverse the effects of drugs on cancer cells via the activation of survival signaling pathways and upregulation of anti-apoptotic proteins such as Bcl-2 and Bcl-xL. Our data show that BaP contribute to the development of chemoresistant cancer cells.