Methylation Induced Gene Silencing of HtrA3 in Smoking-Related Lung Cancer

Exploring the Role of HtrA Family Genes in Cancer: A Systematic Review

PURPOSE

HtrA1, HtrA2, HtrA3 and HtrA4 appear to be involved in the development of pathologies such as cancer. This systematic review reports the results of a literature search performed to compare the expression of HtrA family genes and proteins in cancer versus non-cancer tissues and cell lines, assess relationships between HtrA expression and cancer clinical features in cancer, and analyse the molecular mechanism, by which HtrA family affects cancer.

METHODS

The literature search was conducted according to the PRISMA statement among four databases (PubMed, Web of Science, Embase and Scopus).

RESULTS

A total of 38 articles met the inclusion criteria and involved the expression of HtrA family members and concerned the effect of HtrA expression on cancer and metastasis development or on the factor that influences it. Additionally, 31 reports were retrieved manually. Most articles highlighted that HtrA1 and HtrA3 exhibited tumour suppressor activity, while HtrA2 was associated with tumour growth and metastasis. There were too few studies to clearly define the role of the HtrA4 protease in tumours.

CONCLUSION

Although the expression of serine proteases of the HtrA family was dependent on tumour type, stage and the presence of metastases, most articles indicated that HtrA1 and HtrA3 expression in tumours was downregulated compared with healthy tissue or cell lines. The expression of HtrA2 was completely study dependent. The limited number of studies on HtrA4 expression made it impossible to draw conclusions about differences in expression between healthy and tumour tissue. The conclusions drawn from the study suggest that HtrA1 and HtrA3 act as tumour suppressors.

Identification of MicroRNAs Regulating Clostridium perfringens Type C Infection in the Spleen of Diarrheic Piglets

Clostridium perfringens (C. perfringens) type C is one of the common bacteria in piglet diarrhea, which seriously affects the swine industry's development. The spleen plays crucial roles in the resistance and elimination of pathogenic microorganisms, and miRNAs play important roles in regulating piglet diarrhea caused by pathogens. However, the mechanism by which miRNAs in the spleen are involved in regulating C. perfringens type C causing diarrhea in piglets remains unclear. The expression profiles of the spleen miRNAs of 7-day-old piglets challenged by C. perfringens type C were studied using small RNA-sequencing in control (SC), susceptible (SS), and resistant (SR) groups. Eight-eight differentially expressed miRNAs were screened. The KEGG pathway analysis of target genes revealed that the miRNAs were involved in the MAPK, p53, and ECM-receptor interaction signaling pathways. NFATC4 was determined to be a direct target of miR-532-3p and miR-133b using a dual-luciferase reporter assay. Thus, miR-133b and miR-532-3p targeted to NFATC4 were likely involved to piglet resistance to C. perfringens type C. This paper provides the valuable resources to deeply understand the genetic basis of C. perfringens type C resistance in piglets and a solid foundation to identify novel markers of C. perfringens type C resistance.

Reactive Species in Progeroid Syndromes and Aging-Related Processes

Significance: Reactive species have been classically considered causative of age-related degenerative processes, but the scenario appears considerably more complex and to some extent counterintuitive than originally anticipated. The impact of reactive species in precocious aging syndromes is revealing new clues to understand and perhaps challenge the resulting degenerative processes. Recent Advances: Our understanding of reactive species has considerably evolved, including their hormetic effect (beneficial at a certain level, harmful beyond this level), the occurrence of diverse hormetic peaks in different cell types and organisms, and the extended type of reactive species that are relevant in biological processes. Our understanding of the impact of reactive species has also expanded from the dichotomic damaging/signaling role to modulation of gene expression. Critical Issues: These new concepts are affecting the study of aging and diseases where aging is greatly accelerated. We discuss how notions arising from the study of the underlying mechanisms of a progeroid disease, Cockayne syndrome, represent a paradigm shift that may shed a new light in understanding the role of reactive species in age-related degenerative processes. Future Issues: Future investigations urge to explore established and emerging notions to elucidate the multiple contributions of reactive species in degenerative processes linked to pathophysiological aging and their possible amelioration. Antioxid. Redox Signal. 37, 208-228.

Construction of a single nucleotide variant score-related gene-based prognostic model in hepatocellular carcinoma: analysis of multi-independent databases and validation in vitro

BACKGROUND

The accumulation of single nucleotide variants (SNVs) and the emergence of neoantigens can affect tumour proliferation and the immune microenvironment. However, the SNV-related immune microenvironment characteristics and key genes involved in hepatocellular carcinoma (HCC) are still unclear. We aimed to evaluate differences in the SNV-related immune microenvironment, construct a prognostic model and validate the key genes in vitro.

METHODS

The categories of samples were defined by the expression of SNV score-related genes to evaluate the differences in mutational features, immune environment and prognosis. The survival model was constructed with survival-associated genes and verified in two independent test datasets. RCAN2, the key gene screened out for biofunction, was validated in vitro.

RESULTS

IC2, among the three integrated clusters (IC1, IC2, IC3) classified by the 82 SNV score-related genes, was distinct from the rest in SNV score and immune cell infiltration, showing a better prognosis. Seven prognostic markers, HTRA3, GGT5, RCAN2, LGALS3, CXCL1, CLEC3B, and CTHRC1, were screened to construct a prognostic model. The survival model distinguished high-risk patients with poor prognoses in three independent datasets (log-rank P < 0.0001, 0.011, and 0.0068, respectively) with acceptable sensitivity and specificity. RCAN2 was inversely correlated with NK cell infiltration, and knockdown of RCAN2 promoted proliferation in HCC.

CONCLUSIONS

This study revealed the characteristics of the HCC SNV-associated subgroup and screened seven latent markers for their accuracy of prognosis. Additionally, RCAN2 was preliminarily proven to influence proliferation in HCC and it had a close relationship with NK cell infiltration in vitro. With the capability to predict HCC outcomes, the model constructed with seven key differentially expressed genes offers new insights into individual therapy.

Overview of Human HtrA Family Proteases and Their Distinctive Physiological Roles and Unique Involvement in Diseases, Especially Cancer and Pregnancy Complications

The mammalian high temperature requirement A (HtrA) proteins are a family of evolutionarily conserved serine proteases, consisting of four homologs (HtrA1-4) that are involved in many cellular processes such as growth, unfolded protein stress response and programmed cell death. In humans, while HtrA1, 2 and 3 are widely expressed in multiple tissues with variable levels, HtrA4 expression is largely restricted to the placenta with the protein released into maternal circulation during pregnancy. This limited expression sets HtrA4 apart from the rest of the family. All four HtrAs are active proteases, and their specific cellular and physiological roles depend on tissue type. The dysregulation of HtrAs has been implicated in many human diseases such as cancer, arthritis, neurogenerative ailments and reproductive disorders. This review first discusses HtrAs broadly and then focuses on the current knowledge of key molecular characteristics of individual human HtrAs, their similarities and differences and their reported physiological functions. HtrAs in other species are also briefly mentioned in the context of understanding the human HtrAs. It then reviews the distinctive involvement of each HtrA in various human diseases, especially cancer and pregnancy complications. It is noteworthy that HtrA4 expression has not yet been reported in any primary tumour samples, suggesting an unlikely involvement of this HtrA in cancer. Collectively, we accentuate that a better understanding of tissue-specific regulation and distinctive physiological and pathological roles of each HtrA will improve our knowledge of many processes that are critical for human health.

HtrA serine proteases in cancers: A target of interest for cancer therapy

The HtrA protein family is composed by evolutionally-conserved serine proteases, which are homologous to the HtrA protein of the model bacterium Escherichia coli. They are widely distributed in organisms including humans, prokaryotes and eukaryotes. Moreover, HtrA family proteins are important regulators of a variety of human physiological processes, which contains the maintenance of mitochondrial homeostasis, cellular signal transduction and apoptosis regulation. The HtrA family has been found to be associated with cancer and could be used as a target for future cancer treatments. The purpose of this article is to review the relationship between these HtrA and cancer and to summarize the latest researches on HtrA and cancer.

Rebalancing the Oral Microbiota as an Efficient Tool in Endocrine, Metabolic and Immune Disorders

The current treatment and prevention procedures of oral disorders follow a very targeted approach considering mouth and its structures as a system that is completely independent, than the rest of the body. The main therapeutic approach is to keep the levels of oral bacteria and hygiene in an acceptable range compatible with oral-mouth health, completely separated from systemic microbial homeostasis (eubiosis vs dysbiosis). This can negatively impact the diagnosis of a more complex systemic disease and its progression. Dysbiosis occurs as a consequence of imbalance in oral and gut microbiota which leads to cardiovascular diseases, diabetes mellitus, rheumatoid arthritis, and Alzheimer's disease, as reported in current literature. Likewise, there is a need to highlight and develop a novel philosophical approach in the treatments for oral diseases that will necessarily involve nonconventional approaches.

A distinct concerted mechanism of structural dynamism defines activity of human serine protease HtrA3

Human HtrA3 (high-temperature requirement protease A3) is a trimeric multitasking propapoptotic serine protease associated with critical cellular functions and pathogenicity. Implicated in diseases including cancer and pre-eclampsia, its role as a tumor suppressor and potential therapeutic target cannot be ignored. Therefore, elucidating its mode of activation and regulatory switch becomes indispensable towards modulating its functions with desired effects for disease intervention. Using computational, biochemical and biophysical tools, we delineated the role of all domains, their combinations and the critical phenylalanine residues in regulating HtrA3 activity, oligomerization and specificity. Our findings underline the crucial roles of the N-terminus as well as the PDZ domain in oligomerization and formation of a catalytically competent enzyme, thus providing new insights into its structure–function coordination. Our study also reports an intricate ligand-induced allosteric switch, which redefines the existing hypothesis of HtrA3 activation besides opening up avenues for modulating protease activity favorably through suitable effector molecules.

Expression of HTRA Genes and Its Association with Microsatellite Instability and Survival of Patients with Colorectal Cancer

HtrA proteases regulate cellular homeostasis and cell death. Their dysfunctions have been correlated with oncogenesis and response to therapeutic treatment. We investigated the relation between HtrA1-3 expression and clinicopathological, and survival data, as well as the microsatellite status of tumors. Sixty-five colorectal cancer patients were included in the study. The expression of HTRA1-3 was estimated at the mRNA and protein levels by quantitative PCR and immunoblotting. Microsatellite status was determined by high-resolution-melting PCR. We found that the HTRA1 mRNA level was higher in colorectal cancer tissue as compared to the unchanged mucosa, specifically in primary lesions of metastasizing cancer. The levels of HtrA1 and HtrA2 proteins were reduced in tumor tissue when compared to unchanged mucosa, specifically in primary lesions of metastasizing disease. Moreover, a decrease in HTRA1 and HTRA2 transcripts' levels in cancers with a high level of microsatellite instability compared to microsatellite stable ones has been observed. A low level of HtrA1 or/and HtrA2 in cancer tissue correlated with poorer patient survival. The expression of HTRA1 and HTRA2 changes during colorectal carcinogenesis and microsatellite instability may be, at least partially, associated with these changes. The alterations in the HTRA1/2 genes' expression are connected with metastatic potential of colorectal cancer and may affect patient survival.

The HtrA3 protease promotes drug-induced death of lung cancer cells by cleavage of the X-linked inhibitor of apoptosis protein (XIAP)

HtrA3 is a proapoptotic protease shown to promote drug-induced cytotoxicity in lung cancer cells and proposed to have an antitumor effect. However, at the molecular level, the role of HtrA3 in cell death induction is poorly understood. There are two HtrA3 isoforms, a long and a short one, termed HtrA3L and HtrA3S. By performing pull down assays, co-immunoprecipitation and ELISA, we showed that HtrA3 formed complexes with the X-linked inhibitor of apoptosis protein (XIAP). The recombinant HtrA3 variants ΔN-HtrA3L and -S, lacking the N-terminal regions that are not essential for protease activity, cleaved XIAP with a comparable efficiency, though ΔN-HtrA3S was more active in the presence of cellular extract, suggesting the existence of an activating factor. Immunofluorescence and proximity ligation assays indicated that HtrA3 partially co-localized with XIAP. Exogenous ΔN-HtrA3L/S promoted apoptotic death of lung cancer cells treated with etoposide and caused a significant decrease of cellular XIAP levels, in a way dependent on HtrA3 proteolytic activity. These results collectively indicate that both HtrA3 isoforms stimulate drug-induced apoptotic death of lung cancer cells via XIAP cleavage and thus help to understand the molecular mechanism of HtrA3 function in apoptosis and in cancer cell death caused by chemotherapy.

Proteomics analysis of human serum of patients with non-small-cell lung cancer reveals proteins as diagnostic biomarker candidates

Non-small-cell lung carcinomas (NSCLC) is the most common type of lung cancer and it has a poor prognosis, because overall survival after 5 years is 20-25% for all stages. Thus, it is extremely important to increase the survival rate in the early stages NSCLC by focusing on novel screening tests of cancer identifying specific biomarkers expression associated with a more accurate tumor staging and patient prognosis. In this study, we focused our attention on quantitative proteomics of three heavily glycosylated serum proteins: AMBP, α2 macroglobulin, and SERPINA1. In particular, we analyzed serum samples from 20 NSCLC lung adenocarcinoma cancer patients in early and advanced stages, and 10 healthy donors to obtain a relative quantification through the MRM analysis of these proteins that have shown to be markers of cancer development and progression. AMBP, α2 macroglobulin, and SERPINA1 were chosen because all of them possess endopeptidase inhibitor activity and play key roles in cancer. We observe a variation in the expression of these proteins linked to the stage of the disease. Therefore, we believe that proteins like α2 macroglobulin, αmicroglobulin/bikunin, and SERPINA1 could be useful biomarkers for early detection of lung cancer and in monitoring its evolution.

Antagonism between HTRA3 and TGFβ1 Contributes to Metastasis in Non-Small Cell Lung Cancer

High temperature requirement A3 (HTRA3, long and short isoforms) is a member of the HtrA family and has been implicated as a tumor suppressor in cancer progression in multiple cancer types, yet its molecular functions in non-small cell lung cancer (NSCLC) are not well understood. Here, we report that decreased levels of HTRA3 negatively correlate with elevated TGFβ1 in lung tumor tissue with metastasis. Furthermore, high expression of HTRA3 indicated better prognosis independent of TGFβ1 expression. In NSCLC cell lines, exogenous TGFβ1 significantly downregulated the level of HTRA3, especially the long isoform, during induction of epithelial-mesenchymal transition (EMT). Mechanistically, c-Jun, which is elevated by TGFβ1, directly bound the promoter of HTRA3-L and inhibited its transcription. As a negative feedback loop, overexpression of HTRA3-L attenuated TGFβ1-mediated invasion-metastasis cascades via activation of SMAD2/3 and sensitized cells to anti-PD-L1 treatment. Taken together, our findings suggest that in the early stages of cancer, overexpressed HTRA3 acts as a brake on the oncogenic effects of TGFβ1 and inhibits tumor metastasis. In later stages, the role of HTRA3 is weakened and TGFβ1 efficiently promotes EMT in the absence of the HTRA3 brake. SIGNIFICANCE: This study provides new mechanistic insight of the interaction between HTRA3 and TGFβ in lung cancer by illustrating that HTRA3 is a novel mediator acting as a suppressor of TGFβ1-related oncogenic effects.

Hypoxia is involved in the reduction of HtrA3 in patients with endometrial hyperplasia and cancer

Endometrial cancer (EC) has recently become a major gynecological cancer and endometrial hyperplasia increases the risk for developing EC. Previous studies have reported that human high temperature requirement factor A3 (HtrA3), a member of ATP independent serine proteases family, is involved in endometrial carcinogenesis. However, the underlying mechanism of HtrA3 function is unclear in endometrial hyperplasia and cancer. In this study, we investigated that HtrA3 expression was reduced in endometrial hyperplasia as well as EC. The circulating levels of HtrA3 were also significantly reduced in both atypical hyperplasia and EC. Whether hypoxia is involved in the reduction of HtrA3 in EC was further investigated. Immunohistochemistry (IHC) scores of Glut1 and HtrA3 in type 1 and type 2 EC tissues showed the inverse correlation. And hypoxic condition reduced the expression of HtrA3. Furthermore, silencing HtrA3 promoted EC cell migration. Our study demonstrated the reduced levels of HtrA3 in endometrial hyperplasia including atypical hyperplasia which is a premalignant condition; and as the degree of hypoxia increases in EC, HtrA3 eventually loses its expression. Hypoxia is responsible for the reduction of HtrA3 which in turn promotes EC progression. These findings suggested that HtrA3 is an important adaptor in hypoxic regions that drives endometrial cancer development.

Methylation and expression of PTPN22 in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a fatal disease contributed by both genetic and epigenetic factors. The epigenetic alteration of protein tyrosine phosphatase non-receptor type 22 (PTPN22) and its clinical significance in ESCC were still not yet clarified. A quantitative methylation study of PTPN22 and its expression were conducted in 121 and 31 paired tumor and adjacent normal tissue (ANT), respectively. Moreover, the association between PTPN22 methylation and clinicopathological parameters was evaluated. We found that the methylation level of PTPN22 was significantly elevated in tumor tissues (66.3%) relative to ANT (62.1%) (p=0.005). The methylation level of non-smoking ANT (59.1%) was significant lower than smoking ESCC tissue (65.8%) (p=0.03); similarly, the methylation levels in ANT with no lymph node invasion (57.6%) were significant lower than tumor tissues with lymph node invasion (67.5%) (p=0.001). PTPN22 expression in ESCC was lower than normal tissues, however the difference was not statistically significant (p=0.55). Lower expression was more frequently occurred in N_1-3 and III stage patients, while higher expression was more likely to occur in N₀ and I-II stage patients. Lower expression of PTPN22 was associated with poor overall survival (p=0.04). Taken together, PTPN22 was hypermethylationed in ESCC. Hypermethylation was associated with lymph node invasion. The PTPN22 expression may act as a prognostic biomarker to identify patients at risk of high grade.

HtrA3 is a cellular partner of cytoskeleton proteins and TCP1α chaperonin

The human HtrA3 protease is involved in placentation, mitochondrial homeostasis, stimulation of apoptosis and proposed to be a tumor suppressor. Molecular mechanisms of the HtrA3 functions are poorly understood and knowledge concerning its cellular targets is very limited. There are two HtrA3 isoforms, the long (HtrA3L) and short (HtrA3S). Upon stress, their N-terminal domains are removed, resulting in the more active ΔN-HtrA3. By pull down and mass spectrometry techniques, we identified a panel of putative ΔN-HtrA3L/S substrates. We confirmed that ΔN-HtrA3L/S formed complexes with actin, β-tubulin, vimentin and TCP1α in vitro and in a cell and partially co-localized with the actin and vimentin filaments, microtubules and TCP1α in a cell. In vitro, both isoforms cleaved the cytoskeleton proteins, promoted tubulin polymerization and displayed chaperone-like activity, with ΔN-HtrA3S being more efficient in proteolysis and ΔN-HtrA3L - in polymerization. TCP1α, essential for the actin and tubulin folding, was directly bound by the ΔN-HtrA3L/S but not cleaved. These results indicate that actin, β-tubulin, vimentin, and TCP1α are HtrA3 cellular partners and suggest that HtrA3 may influence cytoskeleton dynamics. They also suggest different roles of the HtrA3 isoforms and a possibility that HtrA3 protease may also function as a co-chaperone.

SIGNIFICANCE

The HtrA3 protease stimulates apoptosis and is proposed to be a tumor suppressor and a therapeutic target, however little is known about its function at the molecular level and very few HtrA3 physiological substrates have been identified so far. Furthermore, HtrA3 is the only member of the HtrA family of proteins which, apart from the long isoform possessing the PD and PDZ domains (HtrA3L), has a short isoform (HtrA3S) lacking the PDZ domain. In this work we identified a large panel (about 150) of the tentative HtrA3L/S cellular partners which provides a good basis for further research concerning the HtrA3 function. We have shown that the cytoskeleton proteins actin, β-tubulin and vimentin, and the TCP1α chaperonin are cellular partners of both HtrA3 isoforms. Our findings indicate that HtrA3 may promote destabilization of the actin and vimentin cytoskeleton and suggest that it may influence the dynamics of the microtubule network, with the HtrA3S being more efficient in cytoskeleton protein cleavage and HtrA3L - in tubulin polymerization. Also, we have shown for the first time that HtrA3 has a chaperone-like, holdase activity in vitro - activity typical for co-chaperone proteins. The proposed HtrA3 influence on the cytoskeleton dynamics may be one of the ways in which HtrA3 promotes cell death and affects cancerogenesis. We believe that the results of this study provide a new insight into the role of HtrA3 in a cell and further confirm the notion that HtrA3 should be considered as a target of new anti-cancer therapies.

High temperature requirement A3 (HTRA3) expression predicts postoperative recurrence and survival in patients with non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide, and its recurrence rate after complete resection is high, owing to local or distant metastases. Low expression of high temperature requirement A3 (HTRA3) has been reported to promote tumorigenesis, diminish the effects of anti-tumor treatments, and correlate with a malignant phenotype. To assess the involvement of HTRA3 in the prognosis of postoperative NSCLC, we obtained tumors from 78 patients who had undergone complete surgical resection, and immunohistochemically examined them for HTRA3 expression. HTRA3 was significantly down-regulated in lung cancer tissues compared with normal lung tissues, and only six tumor cases(7.7%) exhibited relatively high levels of HTRA3 (P < 0.001). Notably, high-HTRA3 patients were at significantly lower risk of postoperative recurrence than low-HTRA3 or HTRA3-negative patients (0% versus 31.2% and 35.0%; P = 0.044, 0.029, respectively). High expression of HTRA3 also independently indicated longer disease-free survival in Cox regression analysis (hazard ratio 0.39, 95%CI 0.16-0.95, P = 0.038). Ectopic expression of the long isoform of HTRA3 attenuated the invasion of an NSCLC cell line in a Transwell assay, while knockdown of HTRA3 had the converse effect. Thus, HTRA3 suppresses tumor cell invasiveness and may serve as a prognostic biomarker for postoperative recurrence or survival in NSCLC.

Paeoniflorin suppresses pancreatic cancer cell growth by upregulating HTRA3 expression

Paeoniflorin (PF) is an active monoterpene glycoside extracted from Paeonia lactiflora Pall. PF has exhibited antitumor effects in various cancer types. However, the effects of PF in pancreatic cancer are largely unexplored. Here, we showed that PF suppressed growth of pancreatic cancer cell lines Capan-1 and MIAPaCa-2 and profoundly sensitized these cells to X-ray irradiation. Through microarray analysis, we identified HTRA3, a tumor-suppressor candidate gene, as the most increased gene upon PF treatment in Capan-1 cells. Ectopic expression of HTRA3 led to reduced cell proliferation and increased expression of apoptotic protein Bax, suggesting a tumor suppressive role of HTRA3 in pancreatic cancer cells. Together, our results provide a set group of genetic proofs and biological proofs that PF inhibited pancreatic cancer growth by upregulating HTRA3.

Maternal HtrA3 optimizes placental development to influence offspring birth weight and subsequent white fat gain in adulthood

High temperature requirement factor A3 (HtrA3), a member of the HtrA protease family, is highly expressed in the developing placenta, including the maternal decidual cells in both mice and humans. In this study we deleted the HtrA3 gene in the mouse and crossed females carrying zero, one, or two HtrA3-expressing alleles with HtrA3^+/− males to investigate the role of maternal vs fetal HtrA3 in placentation. Although HtrA3^−/− mice were phenotypically normal and fertile, HtrA3 deletion in the mother resulted in intra-uterine growth restriction (IUGR). Disorganization of labyrinthine fetal capillaries was the major placental defect when HtrA3 was absent. The IUGR caused by maternal HtrA3 deletion, albeit being mild, significantly altered offspring growth trajectory long after birth. By 8 months of age, mice born to HtrA3-deficient mothers, independent of their own genotype, were significantly heavier and contained a larger mass of white fat. We further demonstrated that in women serum levels of HtrA3 during early pregnancy were significantly lower in IUGR pregnancies, establishing an association between lower HtrA3 levels and placental insufficiency in the human. This study thus revealed the importance of maternal HtrA3 in optimizing placental development and its long-term impact on the offspring well beyond in utero growth.

Association of Smoking, Alcohol Use, and Betel Quid Chewing with Epigenetic Aberrations in Cancers

Numerous environmental factors such as diet, alcohol use, stress, and environmental chemicals are known to elicit epigenetic changes, leading to increased rates of cancers and other diseases. The incidence of head and neck cancer, one of the most common cancers in Taiwanese males, is increasing: oral cancer and nasopharyngeal carcinoma are ranked fourth and tenth respectively, among the top ten cancers in this group, and a major cause of cancer-related deaths in Taiwanese males. Previous studies have identified smoking, alcohol use, and betel quid chewing as the three major causes of head and neck cancers; these three social habits are commonly observed in Taiwanese males, resulting in an increasing morbidity rate of head and neck cancers in this population. In this literature review, we discuss the association between specific components of betel quid, alcohol, and tobacco, and the occurrence of head and neck cancers, lung cancer, gastrointestinal cancers, and urethral cancer. We focus on regulatory mechanisms at the epigenetic level and their oncogenic effects. The review further discusses the application of FDA-approved epigenetic drugs as therapeutic strategies against cancer.

Structural insights into the activation mechanisms of human HtrA serine proteases

Human HtrA1-4 proteins belong to the HtrA family of evolutionarily conserved serine proteases and function as important modulators of many physiological processes, including maintenance of mitochondrial homeostasis, cell signaling and apoptosis. Disturbances in their action are linked to severe diseases, including oncogenesis and neurodegeneration. The HtrA1-4 proteins share structural and functional features of other members of the HtrA protein family, however there are several significant differences in structural architecture and mechanisms of action which makes each of them unique. Our goal is to present recent studies regarding human HtrAs. We focus on their physiological functions, structure and regulation, and describe current models of activation mechanisms. Knowledge of molecular basis of the human HtrAs' action is a subject of great interest; it is crucial for understanding their relevance in cellular physiology and pathogenesis as well as for using them as targets in future therapies of diseases such as neurodegenerative disorders and cancer.

Role of Proteases in Lung Disease: A Brief Overview

Proteases play an important role in health and disease of the lung. In the normal lungs, proteases maintain their homeostatic functions that regulate processes like its regeneration and repair. Dysregulation of proteases–antiproteases balance is crucial in the manifestation of different types of lung diseases. Chronic inflammatory lung pathologies are associated with a marked increase in protease activities. Thus, in addition to protease activities, inhibition of anti-proteolytic control mechanisms are also important for effective microbial infection and inflammation in the lung. Herein, we briefly summarize the role of different proteases and to some extent antiproteases in regulating a variety of lung diseases.

Aberrant methylation of the TERT promoter in esophageal squamous cell carcinoma

A recent study indicated that upstream of the transcription start site (UTSS) hypermethylation of the telomerase reverse transcriptase (TERT) gene was associated with tumor progression and poor prognosis in pediatric brain tumors. The potential for methylation-mediated regulation of the UTSS region of the TERT gene in esophageal squamous cell carcinoma (ESCC) has not yet been investigated. Here, TERT methylation was investigated in tumor and paired adjacent non-cancerous tissues (ANT) from 185 ESCC patients, and the expression of TERT was investigated in 26 tumors paired with ANTs selected from the same cohort. The methylation level of TERT was analyzed in three different regions: region 1, region 2, and the UTSS region. Comparison and correlation of methylation level and clinical features were analyzed in the abovementioned regions. The results showed that the methylation level of TERT was significantly elevated in the tumor relative to the ANT in ESCC. TERT RNA expression was significantly reduced in primary tumors. Tumor stage was the major determinant of survival. The UTSS region may not be an accessible biomarker for ESCC.

OASIS/CREB3L1 is epigenetically silenced in human bladder cancer facilitating tumor cell spreading and migration in vitro

CREB3L1 has been recently proposed as a novel metastasis suppressor gene in breast cancer. Our current study highlights CREB3L1 expression, regulation, and function in bladder cancer. We demonstrate a significant downregulation of CREB3L1 mRNA expression (n = 64) in primary bladder cancer tissues caused by tumor-specific CREB3L1 promoter hypermethylation (n = 51). Based on pyrosequencing CREB3L1 methylation was shown to be potentially associated with a more aggressive phenotype of bladder cancer. These findings were verified by an independent public data set containing data from 184 bladder tumors. In addition, immunohistochemical evaluation showed that CREB3L1 protein expression is decreased in bladder cancer tissues as well. Interestingly, protein loss is predominately observed in the nuclei of aggressive tumor cells. Based on in vitro models we clearly show that CREB3L1 re-expression mediates suppression of tumor cell migration and colony growth of high grade and invasive bladder cancer cells. The candidate tumor suppressor and TGF-β signaling inhibitor HTRA3 was furthermore identified as putative target gene of CREB3L1 in both invasive J82 bladder cells and primary bladder tumors. Hence, our data provide for the first time evidence that the transcription factor CREB3L1 may have an important role as a putative tumor suppressor in bladder cancer.

Structural and Functional Analysis of Human HtrA3 Protease and Its Subdomains

Human HtrA3 protease, which induces mitochondria-mediated apoptosis, can be a tumor suppressor and a potential therapeutic target in the treatment of cancer. However, there is little information about its structure and biochemical properties. HtrA3 is composed of an N-terminal domain not required for proteolytic activity, a central serine protease domain and a C-terminal PDZ domain. HtrA3S, its short natural isoform, lacks the PDZ domain which is substituted by a stretch of 7 C-terminal amino acid residues, unique for this isoform. This paper presents the crystal structure of the HtrA3 protease domain together with the PDZ domain (ΔN-HtrA3), showing that the protein forms a trimer whose protease domains are similar to those of human HtrA1 and HtrA2. The ΔN-HtrA3 PDZ domains are placed in a position intermediate between that in the flat saucer-like HtrA1 SAXS structure and the compact pyramidal HtrA2 X-ray structure. The PDZ domain interacts closely with the LB loop of the protease domain in a way not found in other human HtrAs. ΔN-HtrA3 with the PDZ removed (ΔN-HtrA3-ΔPDZ) and an N-terminally truncated HtrA3S (ΔN-HtrA3S) were fully active at a wide range of temperatures and their substrate affinity was not impaired. This indicates that the PDZ domain is dispensable for HtrA3 activity. As determined by size exclusion chromatography, ΔN-HtrA3 formed stable trimers while both ΔN-HtrA3-ΔPDZ and ΔN-HtrA3S were monomeric. This suggests that the presence of the PDZ domain, unlike in HtrA1 and HtrA2, influences HtrA3 trimer formation. The unique C-terminal sequence of ΔN-HtrA3S appeared to have little effect on activity and oligomerization. Additionally, we examined the cleavage specificity of ΔN-HtrA3. Results reported in this paper provide new insights into the structure and function of ΔN-HtrA3, which seems to have a unique combination of features among human HtrA proteases.

Effects of cigarette smoking on metabolism and effectiveness of systemic therapy for lung cancer

INTRODUCTION

Cigarette smoke associated polycyclic aromatic hydrocarbons can induce key drug-metabolizing enzymes of cytochrome P450 and isoforms of the glucuronyl transferases families. These enzymes metabolize several systemic therapies for lung cancer. Induction of these enzymes may lead to accelerated clearance with resultant impact on systemic therapy efficacy and toxicity in smokers compared with nonsmokers. This article reviews published literature regarding the influence of smoking as it relates to alteration of metabolism of systemic therapy in lung cancer.

METHODS

A structured search of the National Library of Medicine's PubMed/MEDLINE identified relevant articles. Data were abstracted and analyzed to summarize the findings.

RESULTS

Studies that analyzed pharmacokinetic data were prospective. Smokers receiving erlotinib exhibited rapid clearance, requiring a higher dose to reach equivalent systemic exposure compared with nonsmokers. Smokers receiving irinotecan also demonstrated increased clearance and lower systemic exposure. There was no difference in clearance of paclitaxel or docetaxel in smokers. Chemotherapy-associated neutropenia was worse in nonsmokers compared with smokers in patients treated with paclitaxel, docetaxel, irinotecan, and gemcitabine.

CONCLUSIONS

Systemic therapy for lung cancer has a narrow therapeutic index such that small changes in plasma concentrations or exposure in smokers may result in suboptimal therapy and poor outcomes. Smoking cessation must be emphasized at each clinical visit. However, prospective trials should take into consideration the effects of smoking history on drug pharmacokinetics and efficacy. The metabolizing enzyme phenotype in smokers may require individualized dose algorithms for specific agents.

Activity-modulating monoclonal antibodies to the human serine protease HtrA3 provide novel insights into regulating HtrA proteolytic activities

Mammalian HtrA (high temperature requirement factor A) proteases, comprising 4 multi-domain members HtrA1-4, play important roles in a number of normal cellular processes as well as pathological conditions such as cancer, arthritis, neurodegenerative diseases and pregnancy disorders. However, how HtrA activities are regulated is not well understood, and to date no inhibitors specific to individual HtrA proteins have been identified. Here we investigated five HtrA3 monoclonal antibodies (mAbs) that we have previously produced, and demonstrated that two of them regulated HtrA3 activity in an opposing fashion: one inhibited while the other stimulated. The inhibitory mAb also blocked HtrA3 activity in trophoblast cells and enhanced migration and invasion, confirming its potential in vivo utility. To understand how the binding of these mAbs modulated HtrA3 protease activity, their epitopes were visualized in relation to a 3-dimensional HtrA3 homology model. This model suggests that the inhibitory HtrA3 mAb blocks substrate access to the protease catalytic site, whereas the stimulatory mAb may bind to the PDZ domain alone or in combination with the N-terminal and protease domains. Since HtrA1, HtrA3 and HtrA4 share identical domain organization, our results establish important foundations for developing potential therapeutics to target these HtrA proteins specifically for the treatment of a number of diseases, including cancer and pregnancy disorders.

Identification of genes with consistent methylation levels across different human tissues

DNA methylation plays an important role in regulating cell growth and disease development. Methylation profiles are examined by bisulfite conversion; however, the lack of markers for bisulfite conversion efficiency and appropriate internal control genes remains a major challenge. To address these issues, we utilized two bioinformatics approaches, coefficients of variances and resampling tests, to identify probes showing stable methylation levels from several independent microarray datasets. Mass spectrometry validated the consistently high methylation levels of the five probes (N4BP2, EGFL8, CTRB1, TSPAN3, and ZNF690) in 13 human tissue types from 24 cell lines. Linear associations between detected methylation levels and methyl concentrations of DNA samples were further demonstrated in three genes (N4BP2, EGFL8, and CTRB1). To summarize, we identified five genes which may serve as internal controls for methylation studies by analyzing large-scale microarray data, and three of them can be used as markers for evaluating the efficiency of bisulfite conversion.

MBD-seq as a cost-effective approach for methylome-wide association studies: demonstration in 1500 case--control samples

AIM

We studied the use of methyl-CpG binding domain (MBD) protein-enriched genome sequencing (MBD-seq) as a cost-effective screening tool for methylome-wide association studies (MWAS).

MATERIALS & METHODS

Because MBD-seq has not yet been applied on a large scale, we first developed and tested a pipeline for data processing using 1500 schizophrenia cases and controls plus 75 technical replicates with an average of 68 million reads per sample. This involved the use of technical replicates to optimize quality control for multi- and duplicate-reads, an in silico experiment to identify CpGs in loci with alignment problems, CpG coverage calculations based on multiparametric estimates of the fragment size distribution, a two-stage adaptive algorithm to combine data from correlated adjacent CpG sites, principal component analyses to control for confounders and new software tailored to handle the large data set.

RESULTS

We replicated MWAS findings in independent samples using a different technology that provided single base resolution. In an MWAS of age-related methylation changes, one of our top findings was a previously reported robust association involving GRIA2. Our results also suggested that owing to the many confounding effects, a considerable challenge in MWAS is to identify those effects that are informative about disease processes.

CONCLUSION

This study showed the potential of MBD-seq as a cost-effective tool in large-scale disease studies.

HtrA3 Is Downregulated in Cancer Cell Lines and Significantly Reduced in Primary Serous and Granulosa Cell Ovarian Tumors

Objective. The high temperature requirement factor A3 (HtrA3) is a serine protease homologous to bacterial HtrA. Four human HtrAs have been identified. HtrA1 and HtrA3 share a high degree of domain organization and are downregulated in a number of cancers, suggesting a widespread loss of these proteases in cancer. This study examined how extensively the HtrA (HtrA1-3) proteins are downregulated in commonly used cancer cell lines and primary ovarian tumors.

Methods. RT-PCR was applied to various cancer cell lines (n=17) derived from the ovary, endometrium, testes, breast, prostate, and colon, and different subtypes of primary ovarian tumors [granulosa cell tumors (n=19), mucinous cystadenocarcinomas (n=6), serous cystadenocarcinomas (n=8)] and normal ovary (n = 9). HtrA3 protein was localized by immunohistochemistry.

Results. HtrA3 was extensively downregulated in the cancer cell lines examined including the granulosa cell tumor-derived cell lines. In primary ovarian tumors, the HtrA3 was significantly lower in serous cystadenocarcinoma and granulosa cell tumors. In contrast, HtrA1 and HtrA2 were expressed in all samples with no significant differences between the control and tumors. In normal postmenopausal ovary, HtrA3 protein was localized to lutenizing stromal cells and corpus albicans. In serous cystadenocarcinoma, HtrA3 protein was absent in the papillae but detected in the mesenchymal cyst wall.

Conclusion. HtrA3 is more extensively downregulated than HtrA1-2 in cancer cell lines. HtrA3, but not HtrA1 or HtrA2, was decreased in primary ovarian serous cystadenocarcinoma and granulosa cell tumors. This study provides evidence that HtrA3 may be the most relevant HtrA associated with ovarian malignancy.

HtrA3 as an early marker for preeclampsia: specific monoclonal antibodies and sensitive high-throughput assays for serum screening

Mammalian HtrA3 (high temperature requirement A3) is a serine protease of the HtrA family. It has two isoforms [long (HtrA3-L) and short (HtrA3-S)] and is important for placental development and cancer progression. Recently, HtrA3 was identified as a potential diagnostic marker for early detection of preeclampsia, a life-threatening pregnancy-specific disorder. Currently there are no high-throughput assays available to detect HtrA3 in human serum. In this study we generated and fully tested a panel of five HtrA3 mouse monoclonal antibodies (mAbs). Three mAbs recognised both HtrA3-L and HtrA3-S and the other two detected HtrA3-L only. All five mAbs were highly specific to HtrA3 and applicable in western blotting and immunohistochemical analysis of endogenous HtrA3 proteins in the mouse and human tissues. Amplified luminescent proximity homogeneous assays-linked immunosorbent assays (AlphaLISAs), were developed to detect HtrA3 isoforms in picomolar levels in serum. The HtrA3 AlphaLISA detected significantly higher serum levels of HtrA3 in women at 13-14 weeks of gestation who subsequently developed preeclampsia compared to gestational-age matched controls. These HtrA3 mAbs are valuable for the development of immunoassays and characterisation of HtrA3 isoform-specific biology. The newly developed HtrA3 AlphaLISA assays are suitable for large scale screening of human serum.

Application of the wheat-germ cell-free translation system to produce high temperature requirement A3 (HtrA3) proteases

Mammalian high temperature requirement A3 (HtrA3) is a serine protease of the HtrA family. It is an important factor for placental development and a tumor suppressor. The biochemical properties of HtrA3 are uncharacterized. One critical step in biochemical characterization is overexpressing and purifying the full-length recombinant protein. However, utility of cell-based expression systems is limited for a protease because of autocleavage. The wheat-germ cell-free translation system is highly efficient at producing "difficult" eukaryotic multidomain proteins and is easily modifiable for protein synthesis at different temperatures. In this study, we evaluated the potential of the wheat-germ cell-free translation system for producing human HtrA3. HtrA3 underwent autocleavage when synthesized at 17 °C. When the synthesis temperature was lowered to 4 °C, full-length HtrA3 was successfully produced and proteolytically active. Catalytic site serine substitution with alanine (S305A) stabilized HtrA3 while abolishing its protease activity. This mutant was readily synthesized and stable at 17 °C. When used with glutathione S-transferase (GST) pull-down assay, S305A HtrA3 was a valuable bait in searching for endogenous HtrA3 binding proteins. Thus, we demonstrated the unique utility of the wheat-germ cell-free translation system for producing and characterizing human HtrA3. These strategies will be likely applicable to a wide range of proteases.

Molecular changes in smoking-related lung cancer

To elucidate the effect of cigarette smoke on developing lung cancer among individuals, numerous genetic and epigenetic factors related to cigarette smoke-induced lung cancers have been widely investigated and a various genes, loci and pathways have been identified as candidates to date. However, the importance of these molecular alterations in the initiation and progression of lung cancer still remains imprecise and different molecules altered in lung cancer are being used for stratification of patients for targeted therapy. There are a number of molecular pathways involved in the development of lung cancer, and environmental factors related to these alterations are still unclear. Furthermore, various genetic alterations determined by candidate gene approach have not been re-evaluated for their functional significance together with epigenetic alterations in the same population. Accumulated evidence suggested that lung cancer in ever smokers and never smokers follow distinct molecular pathways and may therefore respond to distinct therapy. Therefore, additional studies will be essential to re-evaluate the individual risk of developing lung cancer based on the combination of genetic and epigenetic alterations and to set up a guideline to assess the individual risk for lung cancer and for its prevention.

Coordinated DNA methylation and gene expression changes in smoker alveolar macrophages: specific effects on VEGF receptor 1 expression

Cigarette smoking is implicated in numerous diseases, including emphysema and lung cancer. The clinical expression of lung disease in smokers is not well explained by currently defined variations in gene expression or simple differences in smoking exposure. Alveolar macrophages play a critical role in the inflammation and remodeling of the lung parenchyma in smoking-related lung disease. Significant gene expression changes in alveolar macrophages from smokers have been identified. However, the mechanism for these changes remains unknown. One potential mechanism for smoking-altered gene expression is via changes in cytosine methylation in DNA regions proximal to gene-coding sequences. In this study, alveolar macrophage DNA from heavy smokers and never smokers was isolated and methylation status at 25,000 loci determined. We found differential methylation in genes from immune-system and inflammatory pathways. Analysis of matching gene expression data demonstrated a parallel enrichment for changes in immune-system and inflammatory pathways. A significant number of genes with smoking-altered mRNA expression had inverse changes in methylation status. One gene highlighted by this data was the FLT1, and further studies found particular up-regulation of a splice variant encoding a soluble inhibitory form of the receptor. In conclusion, chronic cigarette smoke exposure altered DNA methylation in specific gene promoter regions in human alveolar macrophages.

Lung cancer and its association with chronic obstructive pulmonary disease: update on nexus of epigenetics

PURPOSE OF REVIEW

Chronic obstructive pulmonary disease (COPD) and lung cancer are the leading causes of morbidity and mortality worldwide. The current research is focused on identifying the common and disparate events involved in epigenetic modifications that concurrently occur during the pathogenesis of COPD and lung cancer. The purpose of this review is to describe the current knowledge and understanding of epigenetic modifications in pathogenesis of COPD and lung cancer.

RECENT FINDINGS

This review provides an update on advances of how epigenetic modifications are linked to COPD and lung cancer, and their commonalities and disparities. The key epigenetic modification enzymes (e.g. DNA methyltransferases -- CpG methylation, histone acetylases/deacetylases and histone methyltransferases/demethylases) that are identified to play an important role in COPD and lung tumorigenesis and progression are described in this review.

SUMMARY

Distinct DNA methyltransferases and histone modification enzymes are differentially involved in pathogenesis of lung cancer and COPD, although some of the modifications are common. Understanding the epigenetic modifications involved in pathogenesis of lung cancer or COPD with respect to common and disparate mechanisms will lead to targeting of epigenetic therapies against these disorders.

The role of epigenetics in resistance to Cisplatin chemotherapy in lung cancer

Non-small cell lung cancer (NSCLC) is the most common cause of cancer related death in the world. Cisplatin and carboplatin are the most commonly used cytotoxic chemotherapeutic agents to treat the disease. These agents, usually combined with drugs such as gemcitabine or pemetrexed, induce objective tumor responses in only 20-30% of patients. Aberrant epigenetic regulation of gene expression is a frequent event in NSCLC. In this article we review the emerging evidence that epigenetics and the cellular machinery involved with this type of regulation may be key elements in the development of cisplatin resistance in NSCLC.

HTRA proteases: regulated proteolysis in protein quality control

Controlled proteolysis underlies a vast diversity of protective and regulatory processes that are of key importance to cell fate. The unique molecular architecture of the widely conserved high temperature requirement A (HTRA) proteases has evolved to mediate critical aspects of ATP-independent protein quality control. The simple combination of a classic Ser protease domain and a carboxy-terminal peptide-binding domain produces cellular factors of remarkable structural and functional plasticity that allow cells to rapidly respond to the presence of misfolded or mislocalized polypeptides.