Chan Young Ock

Pan-Cancer Immunogenomic Perspective on the Tumor Microenvironment Based on PD-L1 and CD8 T-Cell Infiltration

Purpose: There is currently no reliable biomarker to predict who would benefit from anti-PD-1/PD-L1 inhibitors. We comprehensively analyzed the immunogenomic properties in The Cancer Genome Atlas (TCGA) according to the classification of tumor into four groups based on PD-L1 status and tumor-infiltrating lymphocyte recruitment (TIL), a combination that has been suggested to be a theoretically reliable biomarker of anti-PD-1/PD-L1 inhibitors. Experimental Design: The RNA expression levels of PD-L1 and CD8A in the samples in the pan-cancer database of TCGA (N = 9,677) were analyzed. Based on their median values, the samples were classified into four tumor microenvironment immune types (TMIT). The mutational profiles, PD-L1 amplification, and viral association of the samples were compared according to the four TMITs. Results: The proportions of TMIT I, defined by high PD-L1 and CD8A expression, were high in lung adenocarcinoma (67.1%) and kidney clear cell carcinoma (64.8%) among solid cancers. The number of somatic mutations and the proportion of microsatellite instable-high tumor in TMIT I were significantly higher than those in other TMITs, respectively (P < 0.001). PD-L1 amplification and oncogenic virus infection were significantly associated with TMIT I, respectively (P < 0.001). A multivariate analysis confirmed that the number of somatic mutations, PD-L1 amplification, and Epstein–Barr virus/human papillomavirus infection were independently associated with TMIT I. Conclusions: TMIT I is associated with a high mutational burden, PD-L1 amplification, and oncogenic viral infection. This integrative analysis highlights the importance of the assessment of both PD-L1 expression and TIL recruitment to predict responders to immune checkpoint inhibitors. Clin Cancer Res; 22(9); 2261–70. ©2016 AACR. See related commentary by Schalper et al., p. 2102

PD-L1 expression is associated with epithelial-mesenchymal transition in head and neck squamous cell carcinoma

Virus-associated malignancies and sarcomatoid cancers correlate with high PD-L1 expression, however, underlying mechanisms remain controversial. We evaluated the correlation between PD-L1 expression and epithelial-mesenchymal transition (EMT) in head and neck squamous cell carcinomas (HNSCC). Tumor tissues from 50 patients with HNSCC were evaluated for PD-L1 by immunohistochemistry, which showed 32 (64.0%) were PD-L1 positive (PD-L1+). Interestingly, PD-L1 expression was significantly associated with EMT (P = 0.010), as assessed by low E-cadherin and high vimentin expression. The overall survival of PD-L1+ patients with EMT features was significantly worse than those without EMT features (P = 0.007). In an independent validation cohort (N = 91), as well as in HNSCC cases of The Cancer Genome Atlas (TCGA) and the Cancer Cell Line Encyclopedia, high PD-L1 expression was also associated with the high probability of an EMT signature, referred from the GEO dataset, GSE4824. Survival analysis confirmed PD-L1+/EMT+ patients had a poorer prognosis than PD-L1+/EMT- patients in the TCGA cohort. PD-L1 positivity can thus be divided into two categories according to the absence or presence of EMT. PD-L1 expression is also independently associated with EMT features in HNSCC.

Prevention of colitis-associated colorectal cancer with 8-hydroxydeoxyguanosine.

Colitis-associated cancer (CAC) is one of clear examples of inflammation–carcinogenesis sequence, by which the strict control of colitis with potent anti-inflammatory or antioxidative agent offers the chance of cancer prevention. Supported with the facts that Rac1 binds and activates STAT3, which are significantly upregulated in inflammatory bowel disease (IBD) as well as CAC, but 8-hydroxydeoxyguanosine (8-oxo-7,8-dihydrodeoxyguanosine or 8-OHdG) paradoxically can block Rac1 activation and subsequent NADPH oxidase (NOX) inactivation in various inflammation models, we hypothesized that attenuated Rac1–STAT3 and COX–NF-κB pathway by exogenous 8-OHdG administration may ameliorate inflammatory signaling in dextran sodium sulfate (DSS)-induced colitis and can prevent CAC. Before commencing carcinogenesis model, we checked whether exogenous 8-OHdG can alleviate IBD, for which interleukin (IL)-10 knockout mice were designed to ingest 5% DSS for 1 week, and 8-OHdG is given through intraperitoneal route daily. 8-OHdG treatment groups significantly reduced pathologic grade of DSS-induced colitis as well as various inflammatory mediators such as TNF-α, IL-6, COX-2, and iNOS in a dose-dependent manner. To document the cancer prevention effects of 8-OHdG, mice were injected azoxymethane followed by drinking 2.5% DSS for 1 week, after which 8-OHdG–containing diets were given for 20 weeks. As results, mice that consumed 8-OHdG–containing diet significantly reduced both tumor incidence and multiplicity. Rac1 activity and phosphorylated STAT3 level were significantly attenuated in the 8-OHdG–treated group. Significantly decreased levels of malondialdehyde, monocyte chemotactic protein-1, matrix metalloproteinasess, COX-2, NOX4, and β-catenin nuclear accumulation were responsible for cancer prevention effects of exogenous 8-OHdG. In conclusion, we clearly showed cancer-preventive effect of exogenous 8-OHdG against CAC. Cancer Prev Res; 4(9); 1507–21. ©2011 AACR.

Acid pump antagonist-provoked HSP27 dephosphorylation and accentuation rescues stomach from indomethacin-induced damages

OBJECTIVE:  Heat shock proteins (HSPs) are crucial for the maintenance of cellular integrity during normal cell growth as well as pathophysiological conditions. While acting as molecular chaperones with their folding activities, HSPs play a cytoprotective role to rescue epithelial cells from several gastric damages including non‐steroidal anti‐inflammatory drugs (NSAIDs) and Helicobacter pylori. Since the exact relationship between HSP27 phosphorylation and biological function remains unknown in NSAID‐induced gastropathy, we hypothesized that revaprazan, a novel acid pump antagonist, can secure significant cytoprotection from NSAID damages through HSP27 accentuation.

The Effect of Induction Chemotherapy Using Docetaxel, Cisplatin, and Fluorouracil on Survival in Locally Advanced Head and Neck Squamous Cell Carcinoma: A Meta-Analysis

Purpose The purpose of this study was to compare the survival of patients with locally advanced head and neck squamous cell carcinoma (LA-HNSCC) undergoing concurrent chemoradiotherapy (CRT) alone with that of patients undergoing induction chemotherapy (IC) using docetaxel, cisplatin, and 5-fluorouracil (TPF) followed by CRT. Materials and Methods A search of the PubMed, EMBASE, and Cochrane Library databases was performed in April 2015 and abstracts from the American Society of Clinical Oncology meetings (2008-2014) were reviewed. Summaries of the results were pooled using a fixed-effect model, and the risk of bias was evaluated using the Cochrane tool. Results A total of six relevant trials comprising 1,280 patients were identified. There was no statistically significant overall survival (OS) advantage for TPF prior to CRT (TPF/CRT) over CRT alone (hazard ratio [HR] 0.92; 95% confidence interval [CI], 0.79 to 1.09; p=0.339). Progression-free survival (PFS) was significantly longer in the TPF/CRT arms (HR, 0.82; 95% CI, 0.70 to 0.95; p=0.009). Patients with non-oropharyngeal LA-HNSCC obtained the greatest OS and PFS benefits from TPF (HR, 0.68; 95% CI, 0.47 to 0.99; p=0.043 and HR, 0.67; 95% CI, 0.48 to 0.94; p=0.022, respectively). The complete response rate was significantly increased (risk ratio [RR], 1.34; 95% CI, 1.14 to 1.56; p < 0.001), and the distant metastasis rate tended to decrease (RR, 0.65; 95% CI, 0.40 to 1.04; p=0.071) in the TPF/CRT arms. Conclusion IC with TPF followed by CRT is not superior to CRT alone for OS. However, PFS and the complete response rate were significantly improved in the TPF/CRT arms. TPF/CRT for patients with nonoropharyngeal LA-HNSCC provided clear survival advantages.

Combined Mutation of Apc, Kras, and Tgfbr2 Effectively Drives Metastasis of Intestinal Cancer

Colorectal cancer is driven by the accumulation of driver mutations, but the contributions of specific mutations to different steps in malignant progression are not fully understood. In this study, we generated mouse models harboring different combinations of key colorectal cancer driver mutations (Apc, Kras, Tgfbr2, Trp53, Fbxw7) in intestinal epithelial cells to comprehensively investigate their roles in the development of primary tumors and metastases. ApcΔ716 mutation caused intestinal adenomas and combination with Trp53R270H mutation or Tgfbr2 deletion induced submucosal invasion. The addition of KrasG12D mutation yielded epithelial-mesenchymal transition (EMT)-like morphology and lymph vessel intravasation of the invasive tumors. In contrast, combinations of ApcΔ716 with KrasG12D and Fbxw7 mutation were insufficient for submucosal invasion, but still induced EMT-like histology. Studies using tumor-derived organoids showed that KrasG12D was critical for liver metastasis following splenic transplantation, when this mutation was combined with either ApcΔ716 plus Trp53R270H or Tgfbr2 deletion, with the highest incidence of metastasis displayed by tumors with a ApcΔ716 KrasG12D Tgfbr2-/- genotype. RNA sequencing analysis of tumor organoids defined distinct gene expression profiles characteristic for the respective combinations of driver mutations, with upregulated genes in ApcΔ716 KrasG12D Tgfbr2-/- tumors found to be similarly upregulated in specimens of human metastatic colorectal cancer. Our results show how activation of Wnt and Kras with suppression of TGFβ signaling in intestinal epithelial cells is sufficient for colorectal cancer metastasis, with possible implications for the development of metastasis prevention strategies.Significance: These findings illuminate how key driver mutations in colon cancer cooperate to drive the development of metastatic disease, with potential implications for the development of suitable prevention strategies. Cancer Res; 78(5); 1334-46. ©2017 AACR.

Attenuation of cysteamine-induced duodenal ulcer with Cochinchina momordica seed extract through inhibiting cytoplasmic phospholipase A2/5-lipoxygenase and activating γ-glutamylcysteine synthetase.

Background and Aim:  Cysteamine is a reducing aminothiol used for inducing duodenal ulcer through mechanisms of oxidative stress related to thiol‐derived H2O2 reaction. Cochinchina momordica saponins have been suggested to be protective against various gastric diseases based on their cytoprotective and anti‐inflammatory mechanisms. This study was aimed to document the preventive effects of Cochinchina momordica seed extract against cysteamine‐induced duodenal ulcer as well as the elucidation of its pharmacological mechanisms.

Heat Shock Protein: Hard Worker or Bad Offender for Gastric Diseases

Heat shock proteins (HSPs) have core housekeeping functions in the cells where they are built-in components of folding, signal transduction pathways, and quality control functions for which they proofread the structure of proteins and repair misfolded conformers. Helicobacter pylori (H. pylori) infection leads to significant inflammations in the gastric mucosa, which is closely associated with development of either precancerous lesion including chronic atrophic gastritis or gastric cancer in addition to, peptic ulcer disease, and mucosa-associated lymphoid tissue (MALT) lymphoma. Therefore, the association between H. pylori infection and role of HSP has been focused as an important issue because there had been rather conflicting publications showing that HSPs as a good worker for defense against H. pylori infection, whereas HSPs as a bad offender contributing to the progression of H. pylori-associated gastric carcinogenesis in addition to aggravation of gastric inflammation. In this paper regarding proteomic discovery of HSPs related to H. pylori-associated gastric diseases, we introduce several evidences obtained from proteomic analysis dealing with friend or foe role of HSP in H. pylori infection from a cellular level to human diseases. The implication of HSPs in alcoholic or NSAIDs-induced gastritis and the intervening of HSPs in biological changes exemplified with TGF-β signaling, key tumor suppressor growth factors regulating inflammation, immune function, and carcinogenesis were further introduced.

Hydrogen Sulfide in the Gastrointestinal Tract: Friend or Foe?

Hydrogen sulfide (H2S) has been engaged in the reversible state of hypothermia, suspended animation-like states, and halitosis in vertebrates. In the gastrointestinal (GI) tract, H2S has been put on the chopping board since a rather conflicting fact exists that inhibition of H2S production causing obstacles in recovery from various animal models of inflammation, reperfusion injury, and compromised circulation or the possibility of therapeutic exploitation of H2S or its donor compounds based on their anti-inflammatory and circulatory preservation. As a third gasotransmitter, together with nitric oxide and carbon monoxide, there are complex interactions between these mediators in their contribution to regulating cell function, vascular responses, and inflammatory reactions. Inspite of these double-edged roles, many concerns have focused on H2S as a potential therapeutic or a newer pathophysiological player. In this chapter, we describe the benevolence or notoriety of H2S in the GI tract.

Free Radicals and Gastric Mucosal Injury

Free radicals in excess high amounts, irrespective of radical and/or nonradical reactive species, are very reactive in nature and impose detrimental influence on living organisms through damaging all major cellular constituents including membrane, cytoplasmic proteins, and even nuclear DNAs, resulting in oxidative stress, whereas nitric oxide (NO), superoxide anion, and related reactive oxygen species (ROS) in low or modest amounts play an important role as regulatory mediators in signaling processes through which many of the ROS-mediated responses, paradoxically, can protect the cells against oxidative stress and maintain redox homeostasis. Compared to primitive organisms, vertebrates have evolved the use of NO and ROS also as signaling molecules for several physiological functions, which are generated by tightly regulated enzymes including NO synthase and NADPH oxidase isoforms, respectively. Simply stated, the problem is provoked by blazed ROS productions far beyond the quenching capacity of cells, by which free radicals are implicated in the pathogenesis of several gastrointestinal diseases, cancer, diabetes mellitus, atherosclerosis, neurodegenerative diseases, rheumatoid arthritis, ischemia and reperfusion injury, and other diverse diseases in addition to senescence. The implication of free radicals in gastric mucosal injuries will be the main focus of the current chapter. The offending systems like NADPH oxidase and NO synthase and defending systems of glutathione and heat shock protein related to gastric mucosal injury will be introduced.