BCAP31 is involved in modulating colorectal cancer cell proliferation via the Emerin/ß-catenin axis.

Understanding the mechanisms of colorectal cancer (CRC) progression is critical for developing innovative treatment strategies. As an endoplasmic reticulum-located protein, B cell receptor-associated protein 31 (BCAP31) has been identified to be highly expressed in multiple cancers. However, its function and molecular mechanism in CRC remain not fully understood. In the present study, BCAP31 expression and its correlation with the clinical stage were analyzed based on TCGA database. We demonstrated that loss of BCAP31 suppressed CRC cell proliferation in vitro and tumor growth in vivo. Mechanistically, we demonstrated that Emerin was an interaction partner and downstream molecule of BCAP31. Knockdown of BCAP31 promoted the nuclear envelope localization of Emerin, leading to a reduction of ß-catenin accumulation in the nucleus, which resulted in downregulation of Wnt/ß-catenin downstream target genes, including c-Myc, cyclin D1, Survivin, and Mcl-1. Moreover, downregulation of Emerin partially restored the BCAP31 depletion-mediated ß-catenin protein level and tumor suppressive effects in CRC cells.Our data highlights the pivotal role of BCAP31 depletion in inhibiting cell proliferation in CRC cells, and mechanistically via Emerin/ß-catenin signaling, which may serve as a promising target for CRC treatment.

SND1 acts as a functional target of miR-330-5p involved in modulating the proliferation, apoptosis and invasion of colorectal cancer cells.

MicroRNAs (miRNAs) play a crucial role in cancer progression due to their capability to modulate the expression of various target genes. However, given the heterogeneity of tumor cells, miRNAs have been confirmed to exert different regulatory effects. Here, bioinformatic analysis results indicated that expression of miR-330-5p is decreased in colorectal cancer (CRC) tissues and inversely correlated with SND1 expression. Notably, ectopic expression of miR-330-5p restrained tumor cell proliferation, migration, and enhance the sensitivity of CRC cells to 5-FU. Moreover, similar phenotypes were substantiated after inhibition of SND1 expression using RNA interference. Conversely, overexpression of SND1 facilitated the malignant phenotypes of CRC cells and restored miR-330-5p-mediated tumor-suppressive activities in CRC cells. Mechanistically, miR-330-5p directly binds to SND1-3'-untranslated region (3'-UTR), thus involving in inhibiting CRC cells proliferation and invasion and promoting apoptosis. Taken together, miR-330-5p may act as a tumor suppressor by targeting the expression of SND1, suggesting that the miR-330-5p/SND1 axis may be a meaningful regulator for CRC intervention.

Identification of novel biallelic variants in BMP15 in two siblings with premature ovarian insufficiency.

BACKGROUND: Premature ovarian insufficiency (POI) occurs in women before the age of 40 years, accompanied by amenorrhea, hypoestrogenism, hypergonadotropinism, and infertility. The pathology of POI is complex and the molecular genetic mechanisms are poorly understood. Bone morphogenetic protein 15 (BMP15) plays a crucial role in oocyte maturation and follicular development through the activation of granulosa cells. Dysfunction of BMP15 causes ovarian dysgenesis and is related to POI. Identifying pathogenic variants contributes to revealing genetic mechanisms and making clinical diagnoses of POI. METHODS: The study involved two sisters diagnosed with POI. Whole-exome sequencing (WES) was performed to identify causative genes. Sanger sequencing was used to validate the mutations in patients with POI and members of the family with no clinical signs or symptoms. The effect of the novel mutations on the BMP15 structure was analyzed by PSIPRED. By over-expressing wild-type (WT) or mutant BMP15 plasmids in vitro, a functional study of the BMP15 mutant was conducted by real-time qPCR and western blotting. Through cocultivation with HEK293T cells, the effects of secreted BMP15 WT and variants on granulosa cell proliferation and apoptosis were detected through a cell counting kit-8 assay and flow cytometric analysis. RESULTS: We identified biallelic variants in BMP15, c.791G > A (p. R264Q) and c.1076C > T (p. P359L), in two siblings with POI. Both sisters carried the same biallelic variants, while the other female members of their family carried only one of them. Structural prediction showed that the variants have not affected the secondary structure of BMP15 but may change the conformation of water molecules around protein surfaces and thermal stability of BMP15. Real-time qPCR showed no significant difference in mRNA levels among WT and the two variants. Western blotting indicated a reduction in BMP15 expression with the c.791G > A and c.1076C > T variants compared to WT. Moreover, mutants 791G > A and 1076C > T impaired the function of secreted BMP15 in promoting granulosa cell proliferation and suppressing cell apoptosis caused by reactive oxygen species. CONCLUSIONS: This study identified novel biallelic variants, c.791G > A and c.1076C > T, of BMP15 in two siblings with POI. Both missense variants reduced the level of the BMP15 protein and impaired the function of BMP15 in promoting granulosa cell proliferation in vitro. Taken together, our findings provide a novel molecular genetic basis and potential pathogenesis of BMP15 variants in POI.

TRX2/Rab35 Interaction Impairs Exosome Secretion by Inducing Rab35 Degradation.

Given that exosomes mediate intercellular communication by delivering cellular components to recipient cells or tissue, they have the potential to be engineered to deliver therapeutic payloads. However, the regulatory mechanism of exosome secretion is poorly understood. In addition, mitochondrial components have been found in exosomes, suggesting communication between mitochondria and exosomes. However, the molecular mechanism of the mitochondria and vesicle interaction remains unclear. Here, we showed that mitochondrial thioredoxin 2 (TRX2) decreased exosome concentrations and inhibited HCT116 cell migration. Coimmunoprecipitation/mass spectrometry (Co-IP/MS) showed that TRX2 interacted with Rab35. TRX2 and Rab35 bound to each other at their N-terminal motifs and colocalized on mitochondria. Furthermore, TRX2 induced Rab35 degradation, resulting in impaired exosome secretion. Additionally, Rab35 mediated the suppressive effects of TRX2 on cell migration, and TRX2 suppressed cell migration through exosomes. Taken together, this study first found an interaction between TRX2 and Rab35. These results revealed a new role for TRX2 in the regulation of exosome secretion and cell migration and explained the upstream regulatory mechanism of Rab35. Furthermore, these findings also provide new molecular evidence for communication between mitochondria and vesicles.

Targeting BAX ubiquitin-binding sites reveals that BAX activation is essential for its ubiquitin-dependent degradation.

BAX is an important proapoptotic protein of the BCL-2 family, and its stability is essential for the regulation of the mitochondrial apoptotic pathway. A previous study revealed that BAX could undergo degradation through the ubiquitin-proteasome pathway. In this study, we identified two lysine sites, K21 and K123, that were critical ubiquitin-binding sites in BAX. Mutation of these two sites prolonged the half-life of BAX and also affected its proapoptotic ability. Intriguingly, we found that ABT-737, a BCL-2 inhibitor, significantly enhanced TRAIL-induced BAX degradation in HCT116 cells and increased TRAIL-induced apoptosis in the HCT116 only with the BAX K21R/K123R mutant, not other BAX mutants. In addition, overexpression of PARKIN, an E3 ubiquitin ligase targeting BAX, dramatically decreased BAX protein level when only treated with ABT-737 in HCT116 cells. Therefore, we speculated that BAX activation is essential for its ubiquitin-dependent degradation.

Expression profiling of planarians shed light on a dual role of programmed cell death during the regeneration.

Most animals hold the ability to regenerate damaged cells, tissues, and even any lost part of their bodies. To date, there is little known about the precise regulatory mechanism of regeneration and many fundamental questions remain unanswered. To further understand the precise regulatory mechanism of regeneration, we used planarian Dugesia japonica as a model and sequenced the transcriptomes of their regenerated tissues at different regeneration stages. Through de novo assembly and expression profiling, we found that Heat shock protein and MAPK pathway were involved into early response of regeneration in D. japonica. In addition, immune response, cell proliferation, and migration were activated during regeneration. Of notes, our results revealed a specific functional role of programmed cell death (PCD) in regeneration of D. japonica. PCD may not only remove the damaged and superfluous tissues for further patterning with regenerated tissues, but also provide signals to trigger neoblasts proliferation and differentiation directly. Together, our results revealed Heat shock protein and MAPK pathway mediated early response of regeneration and found a dual role of PCD in regeneration D. japonica. Meanwhile, we constructed regulatory networks of apoptosis, autophagy, and related signaling pathways and proposed a schematic model, which provided a global landscape of regeneration.

Efficacy of the MEK Inhibitor Cobimetinib and its Potential Application to Colorectal Cancer Cells.

BACKGROUND/AIMS: Mutations in the Ras/Raf/MEK/ERK pathway are detected in 50% of colorectal cancer cases and play a crucial role in cancer development and progression. Cobimetinib is a MEK inhibitor approved for the treatment of advanced melanoma and inhibits the cell viability of other types of cancer cells. METHODS: HCT116 colorectal cancer cells were treated with cobimetinib, and MTT assay, colony formation assay, and flow cytometry were used to evaluate cell viability, cell cycle, and apoptosis, respectively. The expression of genes associated with the cell cycle and apoptosis were evaluated by quantitative real-time PCR and western blotting. To explore use of cobimetinib in colorectal cancer treatment and further understand its mechanisms, RNA-seq technology was used to identify differentially expressed genes (DEGs) between cobimetinib-treated and untreated HCT116 cells. Furthermore, we compared these DEGs with Gene Expression Omnibus data from colorectal cancer tissues and normal colonic epithelial tissues. RESULTS: We found that cobimetinib not only inhibited cell proliferation but also induced G1 phase arrest and apoptosis in HCT116 colorectal cancer cells, suggesting that cobimetinib may useful in colorectal cancer therapy. After cobimetinib treatment, 3,495 DEGs were obtained, including 2,089 upregulated genes and 1,406 downregulated genes, and most of these DEGs were enriched in the cell cycle, DNA replication, and DNA damage repair pathways. Our results revealed that some genes with high expression in colorectal cancer tissues were downregulated by cobimetinib in HCT116 cells, including CCND1, E2F1, CDC25C, CCNE2, MYC, and PCNA. These genes have vital roles in DNA replication and the cell cycle. Furthermore, genes with low expression in colorectal cancer tissues were upregulated by cobimetinib, including PRKCA, PI3K, RTK, and PKC. Based on our results, the PKC and PI3K pathways were activated after cobimetinib treatment, and inhibition of these two pathways can increase the cytotoxicity of cobimetinib in HCT116 cells. Notably, cobimetinib appeared to enhance the efficacy of 5-fluorouracil (5-FU) by decreasing TYMS expression, high expression of which is responsible for 5-FU resistance in colorectal cancer. CONCLUSIONS: Our results suggest the potential use of cobimetinib in colorectal cancer therapy.

Characterization and Analysis of Whole Transcriptome of Giant Panda Spleens: Implying Critical Roles of Long Non-Coding RNAs in Immunity.

BACKGROUND/AIMS: Giant pandas, an endangered species, are a powerful symbol of species conservation. Giant pandas may suffer from a variety of diseases. Owing to their highly specialized diet of bamboo, giant pandas are thought to have a relatively weak ability to resist diseases. The spleen is the largest organ in the lymphatic system. However, there is little known about giant panda spleen at a molecular level. Thus, clarifying the regulatory mechanisms of spleen could help us further understand the immune system of the giant panda as well as its conservation. METHODS: The two giant panda spleens were from two male individuals, one newborn and one an adult, in a non-pathological condition. The whole transcriptomes of mRNA, lncRNA, miRNA, and circRNA in the two spleens were sequenced using the Illumina HiSeq platform. EBseq and IDEG6 were used to observe the differentially expressed genes (DEGs) between these two spleens. Gene Ontology and KEGG analyses were used to annotate the function of DEGs. Furthermore, networks between non-coding RNAs and protein-coding genes were constructed to investigate the relationship between non-coding RNAs and immune-associated genes. RESULTS: By comparative analysis of the whole transcriptomes of these two spleens, we found that one of the major roles of lncRNAs could be involved in the regulation of immune responses of giant panda spleens. In addition, our results also revealed that microRNAs and circRNAs may have evolved to regulate a large set of biological processes of giant panda spleens, and circRNAs may function as miRNA sponges. CONCLUSION: To our knowledge, this is the first report of lncRNAs and circRNAs in giant panda, which could be a useful resource for further giant panda research. Our study reveals the potential functional roles of miRNAs, lncRNAs, and circRNAs in giant panda spleen.

BID mediates selective killing of APC-deficient cells in intestinal tumor suppression by nonsteroidal antiinflammatory drugs.

Colorectal tumorigenesis is driven by genetic alterations in the adenomatous polyposis coli (APC) tumor suppressor pathway and effectively inhibited by nonsteroidal antiinflammatory drugs (NSAIDs). However, how NSAIDs prevent colorectal tumorigenesis has remained obscure. We found that the extrinsic apoptotic pathway and the BH3 interacting-domain death agonist (BID) are activated in adenomas from NSAID-treated patients. Loss of BID abolishes NSAID-mediated tumor suppression, survival benefit, and apoptosis in tumor-initiating stem cells in APC(Min/+) mice. BID-mediated cross-talk between the extrinsic and intrinsic apoptotic pathways is responsible for selective killing of neoplastic cells by NSAIDs. We further demonstrate that NSAIDs induce death receptor signaling in both cancer and normal cells, but only activate BID in cells with APC deficiency and ensuing c-Myc activation. Our results suggest that NSAIDs suppress intestinal tumorigenesis through BID-mediated synthetic lethality triggered by death receptor signaling and gatekeeper mutations, and provide a rationale for developing more effective cancer prevention strategies and agents.

Spatial Compartmentalization Specializes the Function of Aurora A and Aurora B.

Aurora kinase A and B share great similarity in sequences, structures, and phosphorylation motif, yet they show different localizations and play distinct crucial roles. The factors that determine such differences are largely unknown. Here we targeted Aurora A to the localization of Aurora B and found that Aurora A phosphorylates the substrate of Aurora B and substitutes its function in spindle checkpoint. In return, the centrosome targeting of Aurora B substitutes the function of Aurora A in the mitotic entry. Expressing the chimera proteins of the Auroras with exchanged N termini in cells indicates that the divergent N termini are also important for their spatiotemporal localizations and functions. Collectively, we demonstrate that functional divergence of Aurora kinases is determined by spatial compartmentalization, and their divergent N termini also contribute to their spatial and functional differentiation.

Upregulation of Transient Receptor Potential Canonical Channels Contributes to Endotoxin-Induced Pulmonary Arterial Stenosis.

BACKGROUND Septic shock is a pathologic condition caused by endotoxin-producing bacteria, and often associated with severe pulmonary hypertension. Inflammation is a major systemic response to endotoxin; however, it is unknown whether endotoxin has a direct impact on pulmonary arteries that contributes to pathogenesis of pulmonary hypertension. MATERIAL AND METHODS Rat pulmonary arteries and primary pulmonary arterial smooth muscle cells (PASMCs) were cultured in vitro and treated with lipopolysaccharide (LPS) and blockers of transient receptor potential canonical (TRPC) channels. Neointimal growth and arterial stenosis were observed on cryosections of cultured pulmonary arteries. Proliferation of PASMCs was examined by a WST-1 (water-soluble tetrazolium salt) assay. Expression of TRPC genes in pulmonary arteries and PASMCs were detected and quantified by real-time polymerase chain reaction and Western blotting. RESULTS LPS significantly induced neointimal growth and stenosis of pulmonary arteries and promoted proliferation of PASMCs. TRPC channel blockers 2-aminoethoxydiphenyl borate and SKF-96365 inhibited LPS-induced remodeling of pulmonary arteries and PASMC proliferation. Expression of TRPC1/3/4/6 was detected in pulmonary arteries and PASMCs. LPS treatment dramatically increased the expression of TRPC3 and TRPC4 at both messenger RNA and protein levels. CONCLUSIONS LPS stimulates stenosis of pulmonary arteries through enhancement of TRPC-mediated Ca2+ entry into PASMCs, which is caused by upregulation of TRPC3 and TRPC4 channels.

[Drug resistance of colon cancer cells to 5-fluorouracil mediated by microRNA-21].

OBJECTIVE To explore downstream regulatory pathway of microRNA-21 (miR-21) in colon cancer cells (RKO) through detecting miR-21 and its target PDCD4, and the influence of miR-21 regulation on the sensitivity of RKO cells to 5-fluorouracil (5-FU). METHODS 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the effect of 5-FU on the viability of RKO cells with knockout of miR-21 or high expression of PDCD4. Real-time was used to determine the expression of PDCD4, ABCC5 and CD44 in RKO cell after knockout of miR-21. RESULTS MTT assay reveals that the IC50 of 5-FU in RKO-WT cells (52.82 ± 0.06 umol/L) was about 67% higher than in miR-21 knockout cells (32.23 ± 0.05 umol/L) (P < 0.05), and the apoptosis ratio elevated after knockout of miR-21. High expression of PDCD4, a target gene of miR-21, can negatively regulate the expression of ABC transporter ABCC5 and the stem cell marker CD44. CONCLUSION MiR-21 can mediate the drug resistance to 5-FU by inhibiting its target PDCD4, which can regulate the expression of ABCC5 and CD44 genes.

hnRNPH1 maintains mitochondrial homeostasis by establishing NRF1/DRP1 retrograde signaling under mitochondrial stress.

Mitochondrial homeostasis is coordinated through communication between mitochondria and the nucleus. In response to stress, mitochondria generate retrograde signals to protect against their dysfunction by activating the expression of nuclear genes involved in metabolic reprogramming. However, the mediators associated with mitochondria-to-nucleus communication pathways remain to be clarified. Here, we identified that hnRNPH1 functions as a pivotal mediator of mitochondrial retrograde signaling to maintain mitochondrial homeostasis. hnRNPH1 accumulates in the nucleus following mitochondrial stress in a 5'-adenosine monophosphate-activated protein kinase (AMPK)-dependent manner. Accordingly, hnRNPH1 interacts with the transcription factor NRF1 and binds to the DRP1 promoter, enhancing the transcription of DRP1. Furthermore, in the cytoplasm, hnRNPH1 directly interacts with DRP1 and enhances DRP1 Ser616 phosphorylation, thereby increasing DRP1 translocation to mitochondrial outer membranes and triggering mitochondrial fission. Collectively, our findings reveal a novel role for hnRNPH1 in the mitochondrial-nuclear communication pathway to maintain mitochondrial homeostasis under stress and suggest that it may be a potential target for mitochondrial dysfunction diseases.

miR-653-3p promotes genomic instability of colorectal cancer cells via targeting SIRT1/TWIST1 signaling pathway.

Development of colorectal cancer (CRC) accompanied with genomic instability. Genomic instability was promoted by microRNAs (miRNAs) inhibiting key genes in DNA damage repair and spindle assembly processes. Whether miR-653-3p affects genomic instability is unknown. The aim of this study is to explore the effect of miR-653-3p on genomic instability in CRC cells. Based on RT-qPCR analysis, miR-653-3p was highly expressed in CRC cells. Through single-cell electrophoresis assay and chromosome karyotype analysis, we determined ectopic expression of miR-653-3p induced increased DNA damage but inhibited apoptosis by promoting chromosomal instability. Mechanistically, luciferase assay identified the direct interaction of miR-653-3p with the 3' UTR of SIRT1, and western blot analysis indicated miR-653-3p inhibited SIRT1 and then promoted STAT3 phosphorylation and TWIST1 expression. The results of karyotype analysis showed that the upregulation of SIRT1 and the downregulation of TWIST1 caused by the downregulation of miR-653-3p suppressed chromosomal instability. Additionally, our evidence showed that miR-653-3p promoted CRC cell proliferation, migration, and 5-FU resistance, and miR-653-3p induced the development of CRC in the xenograft mice model. Altogether, our evidence suggests that miR-653-3p regulates SIRT1/TWIST1 signaling pathway and plays an important role in promoting genomic instability, proliferation, migration, and chemoresistance of CRC cells, which may serve as a promising therapeutic target for CRC therapy.

miR-15a-5p enhances the malignant phenotypes of colorectal cancer cells through the STAT3/TWIST1 and PTEN/AKT signaling pathways by targeting SIRT4.

Colorectal cancer (CRC) continues to represent one of the major causes of cancer-related mortality and morbidity. MicroRNAs (miRNAs) are confirmed to be involved in modulating substential biological processes by affecting the expression of targeted genes, including carcinogenesis. In the present study, the expression pattern and functional roles of microRNA-15a-5p (miR-15a-5p) in CRC cells were investigated. The data from TCGA database indicated that miR-15a-5p is highly expressed in CRC tissues. Moreover, ectopic expression of miR-15a-5p facilitated the proliferation, migration, and invasion of CRC cells. Furthermore, bioinformatic analysis combinating with dual-luciferase assay revealed that SIRT4 acts as a crucial target of miR-15a-5p. Accordingly, overexpression of SIRT4 suppresses the miR-15a-5p-mediated enhancement in the proliferation, migration, and invasion of CRC cells, while the opposite phenotypes were observed after inhibition of SIRT4. Moreover, we further revealed that miR-15a-5p restrained the expression of SIRT4 to exacerbate the malignant phenotypes by modulating STAT3/TWIST1 and PETN/AKT signaling in CRC cells. Alternatively, inhibition of the miR-15a-5p/SIRT4 axis enhanced the chemosensitivity of 5-fluorouracil- and oxaliplatin-resistant HCT116 cells. Altogether, our evidence suggests that miR-15a-5p plays an essential role in promoting the proliferation, migration, and chemoresistance of CRC cells via targeting SIRT4 to modulate STAT3/TWIST1 and PETN/AKT signaling, which may serve as a promising therapeutic target for CRC therapy.

Molecular evidence for the subspecific differentiation of blue sheep (Pseudois nayaur) and polyphyletic origin of dwarf blue sheep (Pseudois schaeferi).

Blue sheep (Pseudois nayaur), a Central Asian ungulate with restricted geographic distribution, exhibits unclear variation in morphology and phylogeographic structure. The composition of species and subspecies in the genus Pseudois is controversial, particularly with respect to the taxonomic designation of geographically restricted populations. Here, 26 specimens including 5 dwarf blue sheep (Pseudois schaeferi), which were collected from a broad geographic region in China, were analyzed for 2 mitochondrial DNA fragments (cytochrome b and control region sequences). In a pattern consistent with geographically defined subspecies, we found three deeply divergent mitochondrial lineages restricted to different geographic regions. The currently designated two subspecies of blue sheep, Pseudois nayaur nayaur and Pseudois nayaur szechuanensis, were recognized in the phylogenetic trees. In addition, the Helan Mountain population showed distinct genetic characteristics from other geographic populations, and thus should be classified as a new subspecies. In contrast, dwarf blue sheep clustered closely with some blue sheep from Sichuan Province in the phylogenetic trees. Therefore, dwarf blue sheep appear to be a subset of Pseudois nayaur szechuanensis. After considering both population genetic information and molecular clock analysis, we obtained some relevant molecular phylogeographic information concerning the historical biogeography of blue sheep. These results also indicate that western Sichuan was a potential refugium for blue sheep during the Quaternary period.

MicroRNA-21: a ubiquitously expressed pro-survival factor in cancer and other diseases.

MiRNAs are a new class of small RNA molecules that regulate gene expression at the post-transcriptional and translational levels. MiRNAs have been implicated in the control of many vital biological processes including development, cell proliferation, differentiation, and apoptosis. A growing number of studies have shown that miRNAs also play an important role in carcinogenesis and other diseases. Among the miRNAs identified, miRNA-21 is dramatically up-regulated in cancer cells of various origins. It regulates a wide range of genes and pathways involved in cancer initiation, transformation, invasion, and metastasis. MiRNA-21 also acts as a pro-survival factor in cardiovascular diseases. Aberrant expression in these diseases makes miRNA-21 a potential marker for disease diagnosis and prognosis. This review highlights the complex roles that miRNA-21 plays in cancer and cardiovascular diseases and its potential clinical applications.

Pre-Administration of Berberine Exerts Chemopreventive Effects in AOM/DSS-Induced Colitis-Associated Carcinogenesis Mice via Modulating Inflammation and Intestinal Microbiota.

Inflammatory activation and intestinal flora imbalance play an essential role in the development and progression of colorectal cancer (CRC). Berberine (BBR) has attracted great attention in recent years due to its heath-related benefits in inflammatory disorders and tumors, but the intricate mechanisms have not been fully elucidated. In this study, the effects and the mechanism of BBR on colon cancer were investigated in an azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colitis-associated carcinogenesis mice model. Our results showed that pre-administration of BBR showed a decrease in weight loss, disease activity index (DAI) score, and the number of colon tumors in mice, compared with the model group. The evidence from pathological examination indicated that the malignancy of intestinal tumors was ameliorated after pre-administration of BBR. Additionally, pre-administration with BBR suppressed the expression of pro-inflammatory factors (interleukin (IL)-6, IL-1ß, cyclooxygenase (COX)-2 and tumor necrosis factor (TNF)-α) and the cell-proliferation marker Ki67, while expression of the tight junction proteins (ZO-1 and occludin) were increased in colon tissue. Moreover, the levels of critical pathway proteins involved in the inflammatory process (p-STAT3 and p-JNK) and cell cycle regulation molecules (ß-catenin, c-Myc and CylinD1) exhibited lower expression levels. Besides, 16S rRNA sequence analysis indicated that pre-administration of BBR increased the ratio of Firmicutes/Bacteroidetes (F:M) and the relative abundance of potentially beneficial bacteria, while the abundance of cancer-related bacteria was decreased. Gavage with Lactobacillus rhamnosus can improve the anti-tumor effect of BBR. Overall, pre-administration of BBR exerts preventive effects in colon carcinogenesis, and the mechanisms underlying these effects are correlated with the inhibition of inflammation and tumor proliferation and the maintenance of intestinal homeostasis.

Repressing PDCD4 activates JNK/ABCG2 pathway to induce chemoresistance to fluorouracil in colorectal cancer cells.

BACKGROUND: Colorectal cancer (CRC) is the third major cause of cancer-related death worldwide, and fluorouracil (5-FU) is widely used in the treatment of CRC. However, acquired resistance to 5-FU has become an obstacle in the effective treatment of CRC. Adenosine triphosphate (ATP)-binding cassette sub-family G member 2 (ABCG2) has been found highly expressed in CRC patients with poor responsiveness to folinic acid/5-FU/irinotecan. However, the mechanisms of 5-FU resistance regulated by ABCG2 in CRC cells remain to be comprehensively understood. We aimed to explore the upstream mechanisms of ABCG2 involved in the regulation of chemoresistance in CRC cells. METHODS: We investigated the potential mechanisms of 5-FU resistance in HCT116, RKO, RKO microRNA-21 (miR-21) knockout, and acquired 5-FU-resistant HCT116 (HCT116/FUR) cells. The biochemical and biological analyses were conducted using semiquantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blotting, transfections, and rescue experiments, along with cell proliferation, viability, and colony formation assays. In order to investigate the efficacy of inhibiting the c-Jun NH2 terminal kinase (JNK) pathway to overcome 5-FU resistance, HCT116 and 5-FU-resistant HCT116 cells were inoculated into BALB/c-nu/nu mice to establish the cell-derived xenograft model. RESULTS: The results showed that ABCG2 expression in HCT116/FUR cells was higher compared to HCT116 cells. Overexpression of ABCG2 decreased sensitivity to 5-FU in HCT116 cells, but knockdown of ABCG2 decreased the survival rate in HCT116/FUR cells. Additionally, repressing programmed cell death 4 (PDCD4) activated the JNK pathway in HCT116/FUR cells. Overexpression of PDCD4 inhibited phosphorylation of c-Jun and ABCG2 expression, and recovered sensitivity to 5-FU in HCT116/FUR cells. Moreover, treatment with the JNK pathway inhibitor SP600125 downregulated ABCG2 expression and rescued sensitivity to 5-FU in HCT116/FUR cells. We also found that miR-21 expression in HCT116/FUR cells was higher compared to HCT116 cells. Finally, 5-FU treatment in combination with SP600125 significantly decreased tumorigenicity compared to other treatments in vivo. CONCLUSIONS: Our results demonstrated that 5-FU treatment upregulated miR-21, which directly repressed PDCD4, and subsequently activated the JNK pathway, leading to the upregulation of ABCG2 in CRC cells. Inhibition of the JNK pathway overcame acquired 5-FU resistance both in vivo and in vitro.

Is iPS cell the panacea?

In 2006, it was reported that transgenic expression of merely four defined transcription factors (c-Myc, Klf4, Oct4, and Sox2) is sufficient to reprogram somatic cells to a pluripotent state. The resulting induced pluripotent stem (iPS) cells ignited intense interest in the field of life science for their promising applications in basic biology, drug development, and transplantation. However, the underlying problems of iPS cells seem to be ignored. This review shed light on the problems pertaining iPS cells, including the elusive origin, risk of tumorgenesis, and its relationship with natural selection.