Macrophorins H and L, two new HMG-conjugate macrophorins from rihzospheric Penicillium sp. NX-05-G-3.

Macrophorins H (4) and L (5), two rare HMG-conjugate macrophorins along with three known macrophorins (1-3), three DMOA-derived meroterpenoids (6-8) and two ergosterol derivates (9-10) were isolated from sterilized rice medium cultured Penicillium sp. NX-05-G-3. Their structures were elucidated by 1D and 2D NMR. The cytotoxicities of all compounds were evaluated, and compounds 1 and 2 showed extensive cytotoxicity against human cancer cell lines Hela, SCC15, MDA-MB-453 and A549, with IC50 values ranging from 17.6 to 32.8 µM.

Tandem Vinylogous Aldol and Intramolecular [2 + 2] Cycloaddition toward Benzocyclobutenes by UV Light Photocatalysis.

A facile and efficient radical tandem vinylogous aldol and intramolecular [2 + 2] cycloaddition reaction for direct synthesis of cyclobutane-containing benzocyclobutenes (BCBs) under extremely mild conditions without using any photocatalysts is reported. This approach exhibited definite compatibility with functional groups and afforded new BCBs with excellent regioselectivity and high yields. Moreover, detailed mechanism studies were carried out both experimentally and theoretically. The readily accessible, low-cost, and ecofriendly nature of the developed strategy will endow it with attractive applications in organic and medicinal chemistry.

Intestinal aberrant sphingolipid metabolism shaped-gut microbiome and bile acids metabolome in the development of hepatic steatosis.

Conjugated bile acids (CBAs) play major roles in hepatic gene regulation via nuclear S1P-inhibited histone deacetylase (HDACs). Gut microbiota modifies bile acid pool to generate CBAs and then CBAs returned to liver to regulate hepatic genes, fatty liver, and non-alcoholic fatty liver disease (NAFLD). However, it is not yet known how the gut microbiota was modified under the environment of inflammatory bowel disease (IBD). Here, we revealed that aberrant intestinal sphingosine kinases (SphKs), a major risk factor of IBD, modified gut microbiota by increasing the proportions of Firmicutes and Verrucomicrobia, which were associated with the increase in CBAs. When exposed to a high-fat diet (HFD), sphingosine kinases 2 knockout (SphK2KO) mice developed more severity of intestinal inflammation and hepatic steatosis than their wild-type (WT) littermates. Due to knockdown of nuclear SphK2, Sphk2KO mice exhibited an increase in sphingosine kinases 1 (SphK1) and sphingosine-1-phosphate (S1P) in intestinal epithelial cells. Therefore, the microbiota was modified in the environment of the SphK1/S1P-induced IBD. 16S rDNA amplicon sequencing of cecal contents indicated an increase of Firmicutes and Verrucomicrobia. Ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) measured an increase in CBAs, including taurocholic acid (TCA), taurodeoxycholic acid (TDCA), and glycocholic acid (GCA), in cecal contents and liver tissues of Sphk2KO mice. These CBAs accumulated in the liver promoted hepatic steatosis through downregulating the acetylation of H3K9, H3K14, H3K18 and H3K27 due to the CBAs-S1PR2-nuclear SphK2-S1P signaling pathway was blocked in HFD-SphK2KO mice. In summary, intestinal aberrant sphingolipid metabolism developed hepatic steatosis through the increase in CBAs associated with an increase in Firmicutes and Verrucomicrobia.

Atypical chemokine receptor 3 induces colorectal tumorigenesis in mice by promoting ß-arrestin-NOLC1-fibrillarin-dependent rRNA biogenesis.

Atypical chemokine receptor 3 (ACKR3) has emerged as a key player in various biological processes. Its atypical "intercepting receptor" properties have established ACKR3 as the major regulator in the pathophysiological processes in many diseases. In this study, we investigated the role of ACKR3 activation in promoting colorectal tumorigenesis. We showed that ACKR3 expression levels were significantly increased in human colon cancer tissues, and high levels of ACKR3 predicted the increased severity of cancer. In Villin-ACKR3 transgenic mice with a high expression level of CKR3 in their intestinal epithelial cells, administration of AOM/DSS induced more severe colorectal tumorigenesis than their WT littermates. Cancer cells of Villin-ACKR3 transgenic mice were characterised by the nuclear ß-arrestin-1 (ß-arr1)-activated perturbation of rRNA biogenesis. In HCT116 cells, cotreatment with CXCL12 and AMD3100 selectively activated ACKR3 and induced nuclear translocation of ß-arr1, leading to an interaction of ß-arr1 with nucleolar and coiled-body phosphoprotein 1 (NOLC1). NOLC1, as the phosphorylated protein, further interacted with fibrillarin, a conserved nucleolar methyltransferase responsible for ribosomal RNA methylation in the nucleolus, thereby increasing the methylation in histone H2A and promoting rRNA transcription in ribosome biogenesis. In conclusion, ACKR3 promotes colorectal tumorigenesis through the perturbation of rRNA biogenesis by the ß-arr1-induced interaction of NOLC1 with fibrillarin.

The localization of the alkaloids in Coptis chinensis rhizome by time-of-flight secondary ion mass spectrometry.

Background: Understanding the spatial distribution of active compounds can effectively evaluate the quality of decoction pieces of traditional Chinese medicine (TCM). Traditional methods are economical and practical but lack chemical information on the original distribution. Time-of-flight secondary ion mass spectrometry (TOF-SIMS), with the advantage of non-destructive detection of samples, can directly analyze the distribution of chemical compounds on the surface of various samples. Methods: In this study, TOF-SIMS image analysis technology was used to detect TCM for the first time. Taking Coptis rhizome (CR) as an example, a commonly used TCM, the distribution of the compounds in the cross-section of CR was studied. Meanwhile, ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLCQQQ-MS/MS) was used to verify the results of TOF-SIMS. Results: The distribution of nine active compounds: berberine, epiberberine, coptisine, palmatine, columbamine, jatrorrhizine, tetrahydricheilanthifolinium, and oxyberberine, was well imaged in the cross-section of CR by TOF-SIMS. The content of berberine and epiberberine was the highest; Palmatine distribution in the pith was more than that in other parts; Oxyberberine was mainly concentrated in the cork and xylem rays. Normalization analysis showed contents of these compounds increased along with the growth years. The result was consistent with UPLC-QQQ-MS/MS. Conclusion: The TOF-SIMS method can display the spatial distribution status of the active compounds of herbs, providing a basis for selecting the medicine site with non-destructive and fast detection.

Myricetin and M10, a myricetin-3-O-ß-d-lactose sodium salt, modify composition of gut microbiota in mice with ulcerative colitis.

Our previous studies found that M10, a myricetin-3-O-ß-d-lactose sodium salt, possessed higher effects of ameliorating ulcerative colitis (UC) than Myricetin in mice. Here, we aim to investigate whether the inhibition of UC is the consequence of the effects of M10 that leads to the changed microbiota. Mice model of UC was induced by dextran sulfate sodium (DSS) treatment. M10 and Myricetin were orally administrated for 12 weeks. We performed 16S rDNA sequencing assay to analyze the composition of gut microbiota isolated from ileocecum. Both M10 and Myricetin normalized the composition of Firmicutes and Actinobacteria as healthy mice had. At genus level, the effects of M10 and Myricetin on colitis were associated to the increase of probiotics, such as Akkermansia, and the inhibition of pathogenic microorganisms, such as Ruminococcus and Parabacteroides. M10 had stronger activity than Myricetin in the improvement of biosynthesis and degradation activities, resulting to increasing metabolism of sulfur, pyruvate, steroid biosynthesis and unsaturated fatty acid biosynthesis in gut. Furthermore, M10 normalized the proportion of Firmicutes and Actinobacteria in gut microbiota. It suggests that the improvements in UC are the consequence of the effect of M10 that leads to the changed intestinal microbiota. Conclusion: M10 contributed the pharmacological effects on UC by modification of the intestinal microbiota.

Nuclear translocation of ATG5 induces DNA mismatch repair deficiency (MMR-D)/microsatellite instability (MSI) via interacting with Mis18α in colorectal cancer.

BACKGROUND AND PURPOSE: It is well known that microsatellite instability-high (MSI-H) is associated with 5-fluorouracil (5-FU) resistance in colorectal cancer. MSI-H is the phenotype of DNA mismatch repair deficiency (MMR-D), mainly occurring due to hypermethylation of MLH1 promoter CpG island. However, the mechanisms of MMR-D/MSI-H are unclear. We aim to investigate the pathway of MMR-D/MSI-H involved in 5-FU resistance. EXPERIMENTAL APPROACH: Human colorectal cancer specimens were diagnosed for MSI-H by immunohistochemistry and western blotting. Proteome microarray interactome assay was performed to screen nuclear proteins interacting with ATG5. Nuclear ATG5 and ATG5-Mis18α overexpression were analysed in ATG5high colorectal cancer bearing mice. The methylation assay determined the hypermethylation of hMLH1 promoter CpG island in freshly isolated human colorectal cancer tissue samples and HT29atg5 and SW480atg5 cancer cells. KEY RESULTS: In ATG5high colorectal cancer patients, 5-FU-based therapy resulted in nuclear translocation of ATG5, leading to MSI-H. Colorectal cancer in Atg5 Tg mice demonstrated 5-FU resistance, compared to Atg5+/- and WT mice. Proteome microarray assay identified Mis18α, a protein localized on the centromere and a source for methylation of the underlying chromatin, which responded to the translocated nuclear ATG5 leading to ATG5-Mis18α conjugate overexpression. This resulted in MLH1 deficiency due to hypermethylation of hMLH1 promoter CpG island, while the deletion of nuclear Mis18α failed to induce ATG5-Mis18α complex and MMR-D/MSI-H. CONCLUSIONS AND IMPLICATIONS: Nuclear ATG5 resulted in MMR-D/MSI-H through its interaction with Mis18α in ATG5high colorectal cancer cells. We suggest that ATG5-Mis18α or Mis18α may be a therapeutic target for treating colorectal cancer.

Increased S1P induces S1PR2 internalization to blunt the sensitivity of colorectal cancer to 5-fluorouracil via promoting intracellular uracil generation.

Sphingosine-1-phosphate (S1P), the backbone of most sphingolipids, activating S1P receptors (S1PRs) and the downstream G protein signaling has been implicated in chemoresistance. In this study we investigated the role of S1PR2 internalization in 5-fluorouracil (5-FU) resistance in human colorectal cancer (CRC). Clinical data of randomly selected 60 CRC specimens showed the correlation between S1PR2 internalization and increased intracellular uracil (P < 0.001). Then we explored the regulatory mechanisms in CRC model of villin-S1PR2-/- mice and CRC cell lines. We showed that co-administration of S1P promoted S1PR2 internalization from plasma membrane (PM) to endoplasmic reticulum (ER), thus blunted 5-FU efficacy against colorectal tumors in WT mice, compared to that in S1PR2-/- mice. In HCT116 and HT-29 cells, application of S1P (10 µM) empowered S1PR2 to internalize from PM to ER, thus inducing 5-FU resistance, whereas the specific S1PR2 inhibitor JTE-013 (10 µM) effectively inhibited S1P-induced S1PR2 internalization. Using Mag-Fluo-AM-labeling [Ca2+]ER and LC-ESI-MS/MS, we revealed that internalized S1PR2 triggered elevating [Ca2+]ER levels to activate PERK-eLF2α-ATF4 signaling in HCT116 cells. The activated ATF4 upregulated RNASET2-mediated uracil generation, which impaired exogenous 5-FU uptake to blunt 5-FU therapy. Overall, this study reveals a previously unrecognized mechanism of 5-FU resistance resulted from S1PR2 internalization-upregulated uracil generation in colorectal cancer, and provides the novel insight into the significance of S1PR2 localization in predicting the benefit of CRC patients from 5-FU-based chemotherapy.

M10, a Myricetin-3-O-b-D-Lactose Sodium Salt, Prevents Ulcerative Colitis Through Inhibiting Necroptosis in Mice.

BACKGROUND: M10 is a derivative of Myricetin by adding a hydrophilic glycosylation group. Our previous study revealed that M10 by oral administration prevented colitis-associated colonic cancer (CAC) through attenuating endoplasmic reticulum stress in mice. In current study, we evaluated the inhibitory effects of M10 on ulcerative colitis in mice model, the mechanism of M10 in preventing colitis was further investigated. METHODS: Mice model of ulcerative colitis was induced by continuous oral dextran sodium sulfate (DSS). M10 was given gavage once a day for 12 consecutive weeks. Disease activity index (DAI) was recorded by analyzing the symptoms of colitis. Intestinal barrier was analyzed by the Immunofluorescence staining assay. The structure of microvilli of intestinal epithelial cells was analyzed under Transmission electron microscopy (TEM). TEM assay was also performed to determine the formation of necroptosis in the colonic epithelium with ulcerative colitis. We performed Western blotting assay to analyze the IL-6 and NF-κB pathways, as well as the cytokine cascades related to TNF-α signaling pathway during necroptosis. RESULTS: M10 by oral administration demonstrated a prevention of ulcerative colitis, showing a significant decrease of DAI as compared to the model mice. Pathological analysis indicated that M10 attenuated the degree of colonic inflammation in colonic tissues. M10 restored the structures of intestinal barrier damaged by DSS. M10 prevented the activation of the IL-6 and NF-κB signaling pathways in the inflamed colonic epithelium. Further, M10 prevented necroptosis in the inflamed colonic mucosal cells through down-regulating the TNF-α pathway. Importantly, M10 demonstrated higher activities in preventing ulcerative colitis than Myricetin and control drug Mesalazine. CONCLUSIONS: Myricetin derivative M10 prevents chronic ulcerative colitis through inhibiting necroptosis. M10 could be developed as a promising drug for the treatment of chronic ulcerative colitis.

SphK2 confers 5-fluorouracil resistance to colorectal cancer via upregulating H3K56ac-mediated DPD expression.

Aberrant sphingolipid metabolism has been implicated in chemoresistance, but the underlying mechanisms are still poorly understood. Herein we revealed a previously unrecognized mechanism of 5-fluorouracil (5-FU) resistance contributed by high SphK2-upregulated dihydropyrimidine dehydrogenase (DPD) in colorectal cancer (CRC), which is evidenced from human CRC specimens, animal models, and cancer cell lines. TMA samples from randomly selected 60 CRC specimens firstly identified the clinical correlation between high SphK2 and increased DPD (p < 0.001). Then the regulatory mechanism was explored in CRC models of villin-SphK2 Tg mice, SphK2-/-mice, and human CRC cells xenografted nude mice. Assays of ChIP-Seq and luciferase reporter gene demonstrated that high SphK2 upregulated DPD through promoting the HDAC1-mediated H3K56ac, leading to the degradation of intracellular 5-FU into inactive α-fluoro-ß-alanine (FBAL). Lastly, inhibition of SphK2 by SLR080811 exhibited excellent inhibition on DPD expression and potently reversed 5-FU resistance in colorectal tumors of villin-SphK2 Tg mice. Overall, this study manifests that SphK2high conferred 5-FU resistance through upregulating tumoral DPD, which highlights the strategies of blocking SphK2 to overcome 5-FU resistance in CRC.

Insight into the role of p62 in the cisplatin resistant mechanisms of ovarian cancer.

Cisplatin is a platinum-based first-line drug for treating ovarian cancer. However, chemotherapy tolerance has limited the efficacy of cisplatin for ovarian cancer patients. Research has demonstrated that cisplatin causes changes in cell survival and death signaling pathways through its interaction with macromolecules and organelles, which indicates that investigation into the DNA off-target effects of cisplatin may provide critical insights into the mechanisms underlying drug resistance. The multifunctional protein p62 works as a signaling hub in the regulation of pro-survival transcriptional factors NF-κB and Nrf2 and connects autophagy and apoptotic signals, which play important roles in maintaining cell homeostasis. In this review, we discuss the role of p62 in cisplatin resistance by exploring p62-associated signaling pathways based on current studies and our work. Insights into these resistance mechanisms may lead to more effective therapeutic strategies for ovarian cancer by targeting p62.

S1PR2 inhibitors potently reverse 5-FU resistance by downregulating DPD expression in colorectal cancer.

In this study, S1PR2 was reckoned as a brand-new GPCR target for designing inhibitors to reverse 5-FU resistance. Herein a series of pyrrolidine pyrazoles as the S1PR2 inhibitors were designed, synthesized and evaluated for their activities of anti-FU-resistance. Among them, the most promising compound JTE-013, exhibited excellent inhibition on DPD expression and potent anti-FU-resistance activity in various human cancer cell lines, along with the in vivo HCT116DPD cells xenograft model, in which the inhibition rate of 5-FU was greatly increased from 13.01%-75.87%. The underlying mechanism was uncovered that JTE-013 demonstrated an anti-FU-resistance activity by blocking S1PR2 internalization to the endoplasmic reticulum (ER), which inhibited the degradation of 5-FU into α-fluoro-ß-alanine (FBAL) by downregulating tumoral DPD expression. Overall, JTE-013 could serve as the lead compound for the discovery of new anti-FU-resistance drugs. SIGNIFICANCE: This study provides novel insights that S1PR2 inhibitors could sensitize 5-FU therapy in colorectal cancer.

Correction: CXCR7/CXCR4 heterodimer-induced histone demethylation: a new mechanism of colorectal tumorigenesis.

A correction to this paper has been published and can be accessed via a link at the top of the paper.

[Investigation and application of Dendrobium resources in Qinba Mountains with a discussion on industrial poverty alleviation model].

The Dendrobium species are rare and endangered medicinal plants, and it is difficult to investigate their wild resources with conventional methods because of typical epiphytic herbaceous. We explored Dendrobium resources(include culture resource) of Qinba Mountains and the boundary Mountain area in Hubei, Chongqing using the methods of literatures and field investigation, and found that the cultural base of Dendrobium were profound in Qinba Mountains region. Furthermore, its germplasm resources of Dendrobium were established for the first time in Wanzhou Luotian town. In case the advantages of local rock resources and poverty alleviation demand, we have actively carried out the cultivating mode of Dendrobium which grow on rock, and the poverty alleviation model of local characteristic Dendrobium industry were established preliminarily. Our application case can provide reference for the mining and transformation of traditional Chinese medicine resources census results.

Knockdown of IGF-1R Triggers Viral RNA Sensor MDA5- and RIG-I-Mediated Mitochondrial Apoptosis in Colonic Cancer Cells.

The important role of insulin-like growth factor-1 receptor (IGF-1R) in tumorigenesis has been well established. The classical model involves IGF-1R binding to IGF-1/2, the following activation of PI3K-Akt-signaling cascades, driving cell proliferation and apoptosis inhibition. Here we report a new signal transduction pathway of IGF-1R in the intestinal epithelium. Using heterozygous knockout mice (Igf1r+/-), we analyzed the expressions of viral RNA sensors MDA5 and RIG-I in the intestinal epithelium. Igf1r+/- mice exhibited higher MDA5 and RIG-I than wild-type (WT) mice, indicating that knockdown of IGF-1R could trigger MDA5 and RIG-I. IGF-1R knockdown-triggered MDA5 and RIG-I were further investigated in human colonic cancer cells. Increased MDA5 and RIG-I were clearly seen in the cytoplasm in cancer cells as well as normal human colonic cells with silenced IGF-1R. Notably, the upregulations of MDA5 and RIG-I was not affected by blockage of the PI3K-Akt pathway with LY294002. These results suggested a new signal transduction pathway of IGF-1R. Importantly, IGF-1R knockdown-triggered MDA5 and RIG-I resulted in colorectal cancer apoptosis through activation of the mitochondrial pathway. These in vitro observations were evidenced in the azoxymethane (AOM)-dextran sulfate sodium (DSS) colorectal cancer model of mice. In conclusion, knockdown of IGF-1R triggers viral RNA sensor MDA5- and RIG-I-mediated mitochondrial apoptosis in cancer cells.

Heterozygous knockout insulin-like growth factor-1 receptor (IGF-1R) regulates mitochondrial functions and prevents colitis and colorectal cancer.

Although insulin-like growth factor-1 receptor (IGF-1R) has been accepted as a major determinant of cancers, its biological roles and corresponding mechanisms in tumorigenesis have remained elusive. Herein, we demonstrate that IGF-1R plays pivotal roles in the regulation of mitochondrial respiratory chain and functions during colitis and tumorigenesis. Heterozygous knockout IGF-1R attenuated azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced colitis and colitis associated cancer (CAC) in Igf1r+/- mice. Heterozygous knockout IGF-1R confers resistance to oxidative stress-induced damage on colorectal epithelial cells by protecting mitochondrial dynamics and structures. IGF-1R low expression improves the biological function of mitochondrial fusion under oxidative stress. Mechanically, an increase in respiratory coupling index (RCI) and oxidative phosphorylation index (ADP/O) was seen in colorectal epithelial cells of Igf1r+/- mice. Seahorse XFe-24 analyzer analysis of mitochondrial bioenergetics demonstrated an increase in oxygen consumption rate (OCR) and a decrease of extracellular acidification rate (ECAR) in Igf1r+/- cells. Further analysis suggests the protection mechanisms of Igf1r+/- cells from oxidative stress through the activation of the mitochondrial respiratory chain and LKB1/AMPK pathways. These results highlight the biological roles of IGF-1R at the nexus between oxidative damage and mitochondrial function and a connection between colitis and colorectal cancer.

CXCR7/CXCR4 heterodimer-induced histone demethylation: a new mechanism of colorectal tumorigenesis.

Both chemokine receptors (CXCRs) 7 and 4 can facilitate immune cell migration and mediate a vast array of physiological and pathological events. Herein we report, in both human and animal studies, that these two CXCRs can form heterodimers in vivo and promote colorectal tumorigenesis through histone demethylation. Compared with adjacent non-neoplastic tissue, human colorectal cancer (CRC) tissue showed a significant higher expression of CXCR4 and CXCR7, which was colocalized in the cancer cell epithelium. The CXCR/CXCR4 heterodimerization was associated with increased histone demethylase JMJD2A. Villin-CXCR7-CXCR4 transgenic mice demonstrated a greater degree of exacerbated colitis and tumorigenesis than villin-CXCR7 and villin-CXCR4 mice. The CXCR7/CXCR4 heterodimerization also promoted APC mutation-driven colorectal tumorigenesis in APCMin/+/villin-CXCR7-CXCR4 mice. Further analysis showed that the CXCR7/CXCR4 heterodimer induced nuclear ßarr1 recruitment and histone demethylase JMJD2A, leading to histone demethylation and resulting in transcription of inflammatory factors and oncogenes. This study uncovered a novel mechanism of colorectal tumorigenesis through the CXCR7/CXCR4 heterodimer-induced histone demethylation. Inhibition of CXCR7/CXCR4 heterodimer-induced histone demethylation could be an effective strategy for the prevention and treatment of colorectal cancer.

Analyses of active antioxidant polysaccharides from four edible mushrooms.

Four water-soluble polysaccharides were extracted from Pleurotus eryngii, Flammulina velutipes, Pleurotus ostreatus and white Hypsizygus marmoreus. Using anion exchange and gel permeation chromatography, a neutral and an acidic fraction were purified from each water-soluble polysaccharide. Their molecular weights were all around 20 kDa except that the acidic polysaccharide from Pleurotus ostreatus (named WPOPA) had a lower molecular weight of 5 kDa. Four neutral polysaccharides were mainly composed of galactose (42.7%-69.1%), followed by Man (19.4%-39.3%) and Glc (1.1%-15.9%). Four acidic polysaccharides contained glucose (59.0%-81.8%) as major sugar and minor glucuronic acid (4.5%-9.5%). Acidic polysaccharides exhibited stronger antioxidant activities than neutral fractions, and WPOPA showed the best antioxidant effects. Structural analysis indicated WPOPA had ß-(1 → 6)-glucan backbone branched at O-3 by ß-1,3-d-Glcp, t-ß-d-Glcp and t-ß-d-GlcpA. This investigation would be useful for screening natural antioxidants and significant in developing mushroom polysaccharides as functional foods.

Metformin inhibited colitis and colitis-associated cancer (CAC) through protecting mitochondrial structures of colorectal epithelial cells in mice.

Although a mountain of papers have showed that metformin plays a role in inhibiting cancers, but the mechanism underpinning this has not yet fully elucidated. Herein, we used AOM/DSS model, the clinicopathological features are similar to those found in humans, to investigate the effects of metformin as well as combination with 5-FU in the prevention of colitis and colitis associated cancer (CAC). Oral metformin significantly inhibited DSS-induced ulcerative colitis and AOM/DSS-induced CAC. Metformin also ameliorated 5-FU-induced colorectal gastrointestinal symptoms in mice. Metformin combination with 5-FU strongly inhibited colorectal cancer. Metformin reduced levels of the NFκB signaling components p-IKKα/ß, p-NFκB, p-IκBα in colorectal mucosal cells. Transmission electron microscopy analysis suggested that the inhibition of metformin on colitis and CAC might associate with its biological activity of protecting mitochondrial structures of colorectal epithelial cells. Further analysis by Mito Tracker Red staining assay indicated that metformin prevented H2O2-induced mitochondrial fission correlated with a decrease of mitochondrial perimeter. In addition, metformin increased the level of NDUFA9, a Q-module subunit required for complex I assembly, in colorectal epithelial cells. These observations of metformin in the inhibition of colitis and CAC might associate with its activity of activating the LKB1/AMPK pathway in colorectal epithelial cells. In conclusion, metformin inhibited colitis and CAC through protecting the mitochondrial structures of colorectal epithelial cells.