Autophagy and hypoxia in colonic adenomas related to aggressive features

Autophagic impairment in endometrial polyps: A potential biomarker and therapeutic target

Endometrial polyps are a common gynecological condition associated with abnormal uterine bleeding, infertility, and potential malignancies. This study investigated the expression of key autophagy proteins LC3A/B, p62, and Beclin-1 in endometrial polyps. Twenty patients with endometrial polyps and ten healthy controls were enrolled in a prospective randomized controlled trial. Tissue samples were collected via operative hysteroscopy. ELISA and immunohistochemistry were employed to assess the expression of LC3A/B, p62, and Beclin-1. While ELISA results did not reveal significant differences between the two groups, immunohistochemical analysis demonstrated significantly lower levels of LC3A/B, p62, and Beclin-1 in endometrial polyps compared to healthy endometrial tissue (p = 0.041, p = 0.012, and p = 0.003, respectively). These findings suggest that impaired autophagy, as evidenced by reduced levels of these key autophagy proteins, may contribute to the pathogenesis of endometrial polyps. Further research is needed to elucidate the precise mechanisms underlying this association and to explore potential therapeutic implications.

Berberine for gastric cancer prevention and treatment: Multi-step actions on the Correa's cascade underlie its therapeutic effects

Gastric carcinoma (GC) is a complex multifactorial disease occurring as sequential events commonly referred to as the Correa's cascade, a stepwise progression from non-active or chronic active gastritis, to gastric precancerous lesions, and finally, adenocarcinoma. Therefore, the identification of novel agents with multi-step actions on the Correa's cascade and those functioning as multiple phenotypic regulators are the future direction for drug discovery. Recently, berberine (BBR) has gained traction owing to its pharmacological properties, including anti-inflammatory, anti-cancer, anti-ulcer, antibacterial, and immunopotentiation activities. In this article, we investigated and summarized the multi-step actions of BBR on Correa's cascade and its underlying regulatory mechanism in gastric carcinogenesis for the first time, along with a discussion on the strength of BBR to prevent and treat GC. BBR was found to suppress H. pylori infection, control mucosal inflammation, and promote ulcer healing. In the gastric precancerous lesion phase, BBR could reverse mucosal atrophy and prevent lesions in intestinal metaplasia and dysplasia by regulating inflammatory cytokines, promoting cell apoptosis, regulating macrophage polarization, and regulating autophagy. Additionally, the therapeutic action of BBR on GC was partly realized through the inhibition of cell proliferation, migration, and angiogenesis; induction of apoptosis and autophagy, and enhancement of chemotherapeutic drug sensitivity. BBR exerted multi-step actions on the Correa's cascade, thereby halting and even reversing gastric carcinogenesis in some cases. Thus, BBR could be used to prevent and treat GC. In conclusion, the therapeutic strategy underlying BBR's multi-step action in the trilogy of Correa's cascade may include "prevention of gastric mucosal inflammation (Phase 1); reversal of gastric precancerous lesions (Phase 2), and rescue of GC (Phase 3)". The NF-κB, PI3K/Akt, and MAPK signaling pathways may be the key signaling transduction pathways underlying the treatment of gastric carcinogenesis using BBR. The advantage of BBR over conventional drugs is its multifaceted and long-term effects. This review is expected to provide preclinical evidence for using BBR to prevent gastric carcinogenesis and treat gastric cancer.

Hypoxia Reduces the Transcription of Fibrotic Markers in the Intestinal Mucosa

Introduction

Intestinal fibrosis, characterized by excessive deposition of extracellular matrix proteins, is a common and severe clinical complication of inflammatory bowel disease (IBD). However, the mechanisms underlying fibrosis remain elusive, and currently, there are limited effective pharmacologic treatments that target the development of fibrosis. Hypoxia is one of the key microenvironmental factors influencing intestinal inflammation and has been linked to fibrosis.

Objective

In the present study, we sought to elucidate the impact of hypoxia on fibrotic gene expression in the intestinal mucosa.

Methods

Human volunteers, IBD patients, and dextran sulphate sodium-treated mice were exposed to hypoxia, and colonic biopsies were collected. The human intestinal epithelial cell line Caco-2, human THP-1 macrophages, and primary human gut fibroblasts were subjected to hypoxia, and changes in fibrotic gene expression were assessed.

Results

Human volunteers subjected to hypoxia presented reduced transcriptional levels of fibrotic and epithelial-mesenchymal transition markers in the intestinal mucosa. IBD patients showed a trend towards a decrease in tissue inhibitor of metalloproteinase 1 protein expression. In mice, hypoxic conditions reduced the colonic expression of several collagens and matrix metalloproteinases. Hypoxic Caco-2 cells, THP-1 cells, and primary gut fibroblasts showed a significant downregulation in the expression of fibrotic and tissue remodelling factors.

Conclusions

Stabilization of hypoxia-inducible factors might represent a novel therapeutic approach for the treatment of IBD-associated fibrosis.

MiR-155 contributes to intestinal barrier dysfunction in DSS-induced mice colitis via targeting HIF-1α/TFF-3 axis

Intestinal barrier dysfunction is a hallmark of inflammatory bowel disease (IBD). MiR-155 is increased in colitis and downregulates expression of hypoxia-inducible factor 1α (HIF-1α). Here, we investigated the effects of miR-155 on intestinal barrier dysfunction in dextran sulfate sodium (DSS)-induced colitis. We found that miR-155 antagomir treatment relieved weight loss and intestinal damage in IBD mouse models (P < 0.05). Furthermore, electron microscopy and immunofluorescence imaging showed that miR-155 increased intestinal barrier dysfunction and downregulated the expression of tight junction proteins in DSS-induced colitis. FG-4497, which upregulates HIF-1α expression, elicited protective effects on the intestinal barrier in DSS-induced colitis. Dual luciferase reporter assays also confirmed that miR-155 downregulated expression of HIF-1α. Finally, we discovered that HIF-1α levels were elevated by miR-155 antagomir treatment (P < 0.05) and that TFF-3 expression correlated positively with HIF-1α expression. These results suggest that miR-155 contributes to DSS-induced colitis by promoting intestinal barrier dysfunction and inhibiting the HIF-1α/TFF-3 axis.

Patterns of LC3A Autophagy Protein Expression in Keratoacanthomas

To investigate the expression patterns of autophagy marker light chain protein 3 (LC3A) in keratoacanthoma (KA). KAs are generally regarded as benign but malignant behavior, including rare metastases, may occur. 85 KAs were assessed for the LC3A autophagic protein by immunohistochemistry. Diffuse cytoplasmic staining and a "stone-like structure" (SLS) characterized positive expression. Thirty-four out of 85 KAs (40%) had diffuse cytoplasmic LC3A immunostaining (percentage of positive cells ranging from 5 to 60%). In contrast, only 4 of the 85 KAs (4.7%) expressed SLSs. Only one SLS was detected per histologic section of each tumor. The p53 oncoprotein was encountered in all cases with expression ranging from 1 to 90% of cells (median 30%). The Ki-67 index was expressed in 63 cases (74% of cases; range 1-50% of cells; median value 5%). Neither of these two parameters nor diffuse cytoplasmic LC3A staining was significantly correlated with SLS expression or lack thereof. Expression of SLSs, a hallmark of malignancy, was found in 4.7% of KAs. Further study is necessary to determine whether this fraction represents the exceptional cases that harbor latent malignant potential.

Iron Prevents Hypoxia-Associated Inflammation Through the Regulation of Nuclear Factor-κB in the Intestinal Epithelium

BACKGROUND & AIMS

Hypoxia-associated pathways influence the development of inflammatory bowel disease. Adaptive responses to hypoxia are mediated through hypoxia-inducible factors, which are regulated by iron-dependent hydroxylases. Signals reflecting oxygen tension and iron levels in enterocytes regulate iron metabolism. Conversely, iron availability modulates responses to hypoxia. In the present study we sought to elucidate how iron influences the responses to hypoxia in the intestinal epithelium.

METHODS

Human subjects were exposed to hypoxia, and colonic biopsy specimens and serum samples were collected. HT-29, Caco-2, and T84 cells were subjected to normoxia or hypoxia in the presence of iron or the iron chelator deferoxamine. Changes in inflammatory gene expression and signaling were assessed by quantitative polymerase chain reaction and Western blot. Chromatin immunoprecipitation was performed using antibodies against nuclear factor (NF)-κB and primers for the promoter of tumor necrosis factor (TNF) and interleukin (IL)1β.

RESULTS

Human subjects presented reduced levels of ferritin in the intestinal epithelium after hypoxia. Hypoxia reduced iron deprivation-associated TNF and IL1β expression in HT-29 cells through the induction of autophagy. Contrarily, hypoxia triggered TNF and IL1β expression, and NF-κB activation in Caco-2 and T84 cells. Iron blocked autophagy in Caco-2 cells, while reducing hypoxia-associated TNF and IL1β expression through the inhibition of NF-κB binding to the promoter of TNF and IL1β.

CONCLUSIONS

Hypoxia promotes iron mobilization from the intestinal epithelium. Hypoxia-associated autophagy reduces inflammatory processes in HT-29 cells. In Caco-2 cells, iron uptake is essential to counteract hypoxia-induced inflammation. Iron mobilization into enterocytes may be a vital protective mechanism in the hypoxic inflamed mucosa.

From Colitis to Cancer: An Evolutionary Trajectory That Merges Maths and Biology

Patients with inflammatory bowel disease have an increased risk of developing colorectal cancer, and this risk is related to disease duration, extent, and cumulative inflammation burden. Carcinogenesis follows the principles of Darwinian evolution, whereby somatic cells acquire genomic alterations that provide them with a survival and/or growth advantage. Colitis represents a unique situation whereby routine surveillance endoscopy provides a serendipitous opportunity to observe somatic evolution over space and time in vivo in a human organ. Moreover, somatic evolution in colitis is evolution in the ‘fast lane': the repeated rounds of inflammation and mucosal healing that are characteristic of the disease accelerate the evolutionary process and likely provide a strong selective pressure for inflammation-adapted phenotypic traits. In this review, we discuss the evolutionary dynamics of pre-neoplastic clones in colitis with a focus on how measuring their evolutionary trajectories could deliver a powerful way to predict future cancer occurrence. Measurements of somatic evolution require an interdisciplinary approach that combines quantitative measurement of the genotype, phenotype and the microenvironment of somatic cells–paying particular attention to spatial heterogeneity across the colon–together with mathematical modeling to interpret these data within an evolutionary framework. Here we take a practical approach in discussing how and why the different “evolutionary ingredients” can and should be measured, together with our viewpoint on subsequent translation into clinical practice. We highlight the open questions in the evolution of colitis-associated cancer as a stimulus for future work.

The gastric mucosal protective effects of astragaloside IV in mnng-induced GPL rats

Gastric Cancer is one of the most common types of cancer. And the occurrence of gastric carcinoma is an evolutionary histopathological stage. As a result, further research of GPL, which is a borderline of gastric cancer, is indispensable for preventing the formation and development of gastric carcinoma. Several studies have demonstrated a correlation between the expression of autophagy, apoptosis and Gastric cancer (GC). However, the effects of autophagy and apoptosis on human gastric cancer progression, particularly on gastric precancerous lesions (GPL), have not totally been investigated. At present, Astragaloside IV(AS-IV) is a saponin purified from Astragalus membranaceous Bge, a traditional Chinese herb that has been widely used for more than 2000 y in the treatment of cancer, cardiovascular and immune disorders. This study was designed to investigate the mechanism of AS-IV protecting gastric mucosa in N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced GPL rats. The lesions of GIM and GED were significantly ameliorated compared with the model rats, especially crowded tubular glandular and back-to-back tubular structure, which were the dangerous borderline between GPL and GC. Western Blot analysis showed that the ratio of Bcl-2/Bax and the protein expression of Bcl-XL, p53, Beclin1, p62, ATG5 and ATG12 were decreased and the level of Caspase3 was increased in the group of AS-IV compared with the model group; RT-PCR analysis showed that the gene expression Ambra1, Beclin1, ATG5, LC3 and p62 were decreased in the group of AS-IV compared with the model group. This research manifested that the occurrence of gastric cancer was preceded by a prolonged precancerous stage, which could be ameliorated by the AS-IV. Meanwhile, the mild and moderate stage of precancerous lesions is similar with gastric adenocarcinoma in critical biological processes, including inflammation, cell proliferation, differentiation. But this lesion is very different from cancer, because it does not appear obvious invasion and malignant lesions in this pathologic stag. Further, AS-IV could regulate p53 expression to activate the Ambra1/Beclin1 complex in GPL, and it will protect the gastric mucosal injury, prevent and cure gastric mucosal atrophy, intestinal metaplasia and atypical hyperplastic lesions. It provided a potential therapeutic strategy in reversing intestinal metaplasia and dysplasia of gastric precancerous lesions and protecting the gastric mucosa in GPL rats.

Hypoxia ameliorates intestinal inflammation through NLRP3/mTOR downregulation and autophagy activation

Hypoxia regulates autophagy and nucleotide-binding oligomerization domain receptor, pyrin domain containing (NLRP)3, two innate immune mechanisms linked by mutual regulation and associated to IBD. Here we show that hypoxia ameliorates inflammation during the development of colitis by modulating autophagy and mammalian target of rapamycin (mTOR)/NLRP3 pathway. Hypoxia significantly reduces tumor necrosis factor α, interleukin (IL)-6 and NLRP3 expression, and increases the turnover of the autophagy protein p62 in colon biopsies of Crohn’s disease patients, and in samples from dextran sulfate sodium-treated mice and Il-10^−/− mice. In vitro, NF-κB signaling and NLRP3 expression are reduced through hypoxia-induced autophagy. We also identify NLRP3 as a novel binding partner of mTOR. Dimethyloxalylglycine-mediated hydroxylase inhibition ameliorates colitis in mice, downregulates NLRP3 and promotes autophagy. We suggest that hypoxia counteracts inflammation through the downregulation of the binding of mTOR and NLRP3 and activation of autophagy.

Hypoxia and HIF-1α activation are protective in mouse models of colitis, and the latter regulates autophagy. Here Cosin-Roger et al. show that hypoxia ameliorates intestinal inflammation in Crohn’s patients and murine colitis models by inhibiting mTOR/NLRP3 pathway and promoting autophagy.

Role of Autophagy as a Survival Mechanism for Hypoxic Cells in Tumors

Enhanced autophagy has been observed in hypoxic regions of solid tumors. Here we address the hypothesis that autophagy is required for survival of hypoxic cells. We evaluated sensitivity to hypoxia of three human tumor cell lines (MCF7, PC3, and LNCaP) and their autophagy-deficient variants with shRNA knockdown of the genes ATG7 and BECLIN1. Hypoxia-induced cell death was more rapid for autophagy-deficient cells and was increased in the presence of the proton pump inhibitor pantoprazole that inhibits autophagy. Autophagy-deficient cells had a lower rate of oxygen consumption than wild-type cells. In xenografts derived from the three cell lines, autophagy (as determined by increased LC3 and reduced p62/SQSTM1) colocalized with hypoxic regions (identified by EF5). Xenografts derived from autophagy-deficient cells grew more slowly than wild-type tumors. Both LC3 expression and hypoxia were decreased in xenografts generated from single-knockdown cells and absent in double-knockdown tumors. Our results are consistent with the hypothesis that autophagy facilitates the survival of hypoxic cells, although reduced oxygen consumption of autophagy-deficient cells may contribute to lack of hypoxia in tumors derived from them. Because hypoxia is associated with resistance to anticancer therapy, inhibition of autophagy has potential to enhance the effectiveness of cancer treatment.

Expression patterns of sirtuin 1-AMPK-autophagy pathway in chronic colitis and inflammation-associated colon neoplasia in IL-10-deficient mice

BACKGROUND

Interleukin-10-deficient (IL-10 (-/-)) mice spontaneously develop chronic colitis and adenocarcinoma through the dysplasia sequence. Autophagy malfunction is associated to inflammatory bowel disease (IBD) and colorectal cancer (CRC) pathogenesis. Autophagy is regulated by silent information regulator-1 (SIRT1), a NAD+-dependent histone deacetylase. Our aim was to investigate the expression changes of SIRT1-AMPK-autophagy pathway in the progression from chronic colitis to CRC.

METHODS

We studied C57BL/6-IL-10-deficient mice between 6 and 18weeks of age. Macroscopic and histological analysis, and characterization of inflammatory and tumor biomarkers were performed.

RESULTS

IL-10-deficient mice developed colitis from the age of 6weeks onward. The severity of inflammation and dysplasia, and the proliferative activity increased gradually with age. IL-10 (-/-) mice were characterized by improved levels of TNF-α and decreased expression of SIRT1. Moreover, our findings show an increase in p-AMPK expression and an activation of the autophagy in IL-10 (-/-) mice from all stages, evidenced by the accumulation of LC3-II protein, the increase in Beclin 1 expression and the reduction in Bcl-2 levels.

CONCLUSIONS

SIRT1-AMPK-autophagy pathway may be involved in the maintenance of chronic inflammation and dysplasia development in the IL-10-deficient mice model. Modulation of this pathway could be a novel strategy for IBD and CRC treatment.

Autophagy is upregulated during colorectal carcinogenesis, and in DNA microsatellite stable carcinomas

Cancer cells are exposed to a wide range of stress sources, such as nutrient deprivation and hypoxia, as well as cytotoxic chemotherapy and radiotherapy. Certain forms of stress can also promote survival activating the metabolic autophagy pathway in cancer cells. Autophagy is dramatically increased in cancer cells. In these conditions, it is becoming evident that autophagy protects cells, by providing an alternative energy source and by eliminating dysfunctional organelles or proteins. Its role in tumorigenesis is more controversial and both the presence and the absence of autophagy have been implicated. Autophagy is known to be associated with the poor outcome of patients with various types of cancers, and its effectiveness as a prognostic marker in colorectal cancer was demonstrated by several studies. The inhibition of autophagy may be a potential therapeutic target in colorectal cancer. In vitro experiments have shown that the inhibition of autophagy increases 5-FU-induced apoptosis. There are two trials currently investigating the addition of chloroquine to 5-FU-based chemotherapy and bevacizumab. In the present study, we evaluated the expression of LC3B-II in samples of human colorectal microadenomas (i.e., dysplastic aberrant crypt foci) and carcinomas compared to normal mucosa. Furthermore, the expression pattern of LC3B-II was assessed in carcinomas classified as DNA microsatellite stable (MSS) and unstable (MSI). Thus, immunofluorescence techniques coupled with confocal microscopy and immunoblot experiments were performed. The results clearly showed a significant increase in expression of the autophagic key factor in microadenomas and carcinomas with respect to normal mucosa. In MSS carcinomas, the level of LC3B-II expression was higher than that in the MSI carcinomas.

Enhancement of oxaliplatin-induced cell apoptosis and tumor suppression by 3-methyladenine in colon cancer

Oxaliplatin (OX) has been widely used in adjuvant and palliative treatments of advanced colon cancer; however, cancer cells ultimately become resistant in the majority of cases. Therefore, the development of a novel strategy to overcome this resistance is important for the effective treatment of colon cancer. Cell autophagy reduces the sensitivity of cancer cells to therapeutic reagents in various types of human cancer; therefore, the present study used murine CT26 colon carcinoma cells to explore whether inhibition of autophagy by 3-methyladenine (3-MA) is able to enhance OX-induced apoptosis in vitro and OX-suppressed tumor growth in vivo. CT26 cells were treated with 3-MA, OX, or 3-MA plus OX, and the autophagy, apoptosis and proliferation of the CT26 cells was investigated. Additionally, the therapeutic efficiency of the combination of 3-MA and OX treatment was evaluated in vivo by determining the survival time of the tumor-bearing mice and, thus, tumor growth rate. The treatment of CT26 cells in vitro with OX alone increased autophagy as well as apoptosis, whereas treatment with 3-MA plus OX markedly inhibited OX-induced autophagy, but increased OX-induced cell apoptosis. Furthermore, the combination of OX and 3-MA treatment significantly suppressed tumor growth in vivo and prolonged mouse survival time when compared with OX treatment alone. Similarly, 3-MA increased OX-induced cell apoptosis and decreased autophagy in xenograft tumor tissues. Thus, the administration of 3-MA may increase tumor cell sensitivity to OX by reducing its autophagic effects and enhancing its apoptotic effects. Data obtained in the present study indicates that the clinical combination of an autophagy inhibitor with OX may increase the therapeutic effect of OX and improve the clinical outcome of patients with colon cancer.

β-Catenin promotes colitis and colon cancer through imprinting of proinflammatory properties in T cells

The density and type of lymphocytes that infiltrate colon tumors are predictive of the clinical outcome of colon cancer. High densities of T helper 17 (T(H)17) cells and inflammation predict poor outcome, whereas infiltration by T regulatory cells (Tregs) that naturally suppress inflammation is associated with longer patient survival. However, the role of Tregs in cancer remains controversial. We recently reported that Tregs in colon cancer patients can become proinflammatory and tumor-promoting. These properties were directly linked with their expression of RORγt (retinoic acid-related orphan receptor-γt), the signature transcription factor of T(H)17 cells. We report that Wnt/β-catenin signaling in T cells promotes expression of RORγt. Expression of β-catenin was elevated in T cells, including Tregs, of patients with colon cancer. Genetically engineered activation of β-catenin in mouse T cells resulted in enhanced chromatin accessibility in the proximity of T cell factor-1 (Tcf-1) binding sites genome-wide, induced expression of T(H)17 signature genes including RORγt, and promoted T(H)17-mediated inflammation. Strikingly, the mice had inflammation of small intestine and colon and developed lesions indistinguishable from colitis-induced cancer. Activation of β-catenin only in Tregs was sufficient to produce inflammation and initiate cancer. On the basis of these findings, we conclude that activation of Wnt/β-catenin signaling in effector T cells and/or Tregs is causatively linked with the imprinting of proinflammatory properties and the promotion of colon cancer.

Targeting autophagy as a potential therapeutic approach for melanoma therapy

Melanoma, occurring as a rapidly progressive skin cancer, is resistant to current chemo- and radiotherapy, especially after metastases to distant organs has taken place. Most chemotherapeutic drugs exert their cytotoxic effect by inducing apoptosis, which, however, is often deficient in cancer cells. Thus, it is appropriate to attempt the targeting of alternative pathways, which regulate cellular viability. Recent studies of autophagy, a well-conserved cellular catabolic process, promise to improve the therapeutic outcome in melanoma patients. Although a dual role for autophagy in cancer therapy has been reported, both protecting against and promoting cell death, the potential for using autophagy in cancer therapy seems to be promising. Here, we review the recent literature on the role of autophagy in melanoma with respect to the expression of autophagic markers, the involvement of autophagy in chemo- and immunotherapy, as well as the role of autophagy in hypoxia and altered metabolic pathways employed for melanoma therapy.