EGFR is involved in control of gastric cell proliferation through activation of MAPK and Src signalling pathways in early-weaned rats

Distribution of Troy (Tnfrsf19) in the Gastric Gland During Postnatal Development: Effects of Early Weaning

This study investigates the distribution and role of the stem cell marker Troy (Tnfrsf19) in the gastric mucosa of rats during postnatal development and the effects of early weaning. Troy, previously identified as a reserve stem cell marker in adult gastric tissues, is examined across various developmental stages from birth to adulthood. We showed that Troy+ cells are scattered throughout the gastric gland in early postnatal stages, but they become concentrated in the basal portion of the gland as the rats mature. Additionally, early weaning affects Troy expression at its gene and protein levels, altering its distribution in the gastric mucosa. This suggests that early dietary changes may disrupt the organization and function of the secondary stem cell niche in the stomach, potentially impacting gastric gland homeostasis. We also used in silico analysis to compare the molecular functions of Troy+ zymogenic and parietal cells, finding distinct roles in proliferation and secretion. The results underscore the importance of Troy in gastric development and highlight the long-term impact of early weaning on gastric tissue organization and cell proliferation dynamics.

Transforming Growth Factor α Evokes Aromatase Expression in Gastric Parietal Cells during Rat Postnatal Development

Estrogen, well known as a female hormone, is synthesized primarily by ovarian aromatase. However, extra-glandular tissues also express aromatase and produce estrogen. It is noteworthy that aromatase in gastric parietal cells begins expression around 20 days after birth and continues secreting considerable amounts of estrogen into the portal vein throughout life, supplying it to the liver. Estrogen, which is secreted from the stomach, is speculated to play a monitoring role in blood triglyceride, and its importance is expected to increase. Nevertheless, the regulatory mechanisms of the aromatase expression remain unclear. This study investigated the influence of transforming growth factor α (TGFα) on gastric aromatase expression during postnatal development. The administration of TGFα (50 μg/kg BW) to male Wistar rats in the weaning period resulted in enhanced aromatase expression and increased phosphorylated ERK1+2 in the gastric mucosa. By contrast, administration of AG1478 (5 mg/kg BW), a protein tyrosine kinase inhibitor with high selectivity for the epidermal growth factor receptor and acting as an antagonist of TGFα, led to the suppression of aromatase expression. In fact, TGFα expression in the gastric fundic gland isthmus began around 20 days after birth in normal rats as did that of aromatase, which indicates that TGFα might induce the expression of aromatase in the parietal cells concomitantly.

Breastfeeding lifespan control of growth, maintenance, and metabolism of small intestinal epithelium

Gastrointestinal epithelial cells respond to milk-born molecules throughout breastfeeding, influencing growth, and development. The rapid renewal of the small intestine depends on the proliferation in the crypt that drives cell fates. We used early weaning model to investigate immediate and late effects of breastfeeding on proliferation, differentiation of jejunal epithelial cells. Wistar rats were either allowed to suckle (S) until 21 postnatal days or submitted to early weaning (EW) at 15 days. By comparing ages (18, 60, and 120 days), we found that EW decreased Ki67 indices and villi height at 18 and 60 days (p < 0.05), and at 120 days they were similar between diets. Proliferative reduction and augmented expression of Cdkn1b (p27 gene) were parallel. In the stem cell niche, EW increased the number and activity (Defa24) of Paneth cells at 18 and 60 days (p < 0.05), and Lgr5 and Ascl2 genes showed inverted responses between ages. Among target cells, EW decreased goblet cell number at 18 and 60 days (p < 0.05) and increased it at 120 days (p < 0.05), whereas enteroendocrine marker genes were differentially altered. EW reduced enterocytes density at 18 days (p < 0.05), and at 120 days this population was decreased (vs. 60 days). Among cell fate crypt-controlling genes, Notch and Atoh1 were the main targets of EW. Metabolically, intraperitoneal glucose tolerance was immediately reduced (18 days), being reverted until 120 days (p < 0.05). Currently, we showed that breastfeeding has a lifespan influence on intestinal mucosa and on its stem cell compartment. We suggest that, although jejunum absorptive function is granted after early weaning, the long lasting changes in gene expression might prime the mucosa with a different sensitivity to gut disorders that still have to be further explored.

Lifelong Adaptation of Gastric Cell Proliferation and Mucosa Structure to Early Weaning-Induced Effects

The gastric mucosa is disturbed when breastfeeding is interrupted, and such early weaning (EW) condition permanently affects the differentiation of zymogenic cells. The aim of the study was to evaluate the immediate and long-term effects of EW on gastric cell proliferation, considering the molecular markers for cell cycle, inflammation, and metaplasia. Overall, we investigated the lifelong adaptation of gastric growth. Wistar rats were divided into suckling-control (S) and EW groups, and gastric samples were collected at 18, 30, and 60 days for morphology, RNA, and protein isolation. Inflammation and metaplasia were not identified, but we observed that EW promptly increased Ki-67-proliferative index (PI) and mucosa thickness (18 days). From 18 to 30 days, PI increased in S rats, whereas it was stable in EW animals, and such developmental change in S made its PI higher than in EW. At 60 days, the PI decreased in S, making the indices similar between groups. Spatially, during development, proliferative cells spread along the gland, whereas, in adults, they concentrate at the isthmus-neck area. EW pushed dividing cells to this compartment (18 days), increased PI at the gland base (60 days), but it did not interfere in expression of cell cycle molecules. At 18 days, EW reduced Tgfβ2, Tgfβ3, and Tgfbr2 and TβRII and p27 levels, which might regulate the proliferative increase at this age. We demonstrated that gastric cell proliferation is immediately upregulated by EW, corroborating previous results, but for the first time, we showed that such increased PI is stable during growth and aging. We suggest that suckling and early weaning might use TGFβs and p27 to trigger different proliferative profiles during life course.

Molecular risk markers related to local tumor recurrence at histological margin-free endoscopically resected early gastric cancers: A pilot study

Local recurrences in early gastric cancers (EGCs) after complete endoscopic submucosal dissection (ESD) remain problematic. Here, we investigated the spatially sequential molecular changes in various cancer-related proteins along the axis of the histologically clear but recurrent resection margins (TRM) to determine the appropriate tumor-free margin distance and potential molecular risk markers related to local recurrence. Five eligible patients with recurrent EGCs after complete ESD were selected from 548 EGC patients. The specimens, including recurrent resection margin axis, were divided into 5 zones. Digital spatial profiling assay was performed to quantify the expression level of 31 cancer-related proteins along each zone. p-Chk1 level was significantly reduced in TRM zone than non-recurrent resection margin. The expression of p44/42 ERK and p-Chk1 were significantly decreased along the lateral axis of the recurrent resection margin, with no significance toward the normal zone, which may suggest that p44/42 ERK and p-Chk1 may be involved in the recurrent side compared to non-recurrent margin. Although we could not evaluate more than 5.5 mm, the significant linear decreases in p44/42 ERK and p-Chk1 were maintained until at least 5.5 mm from the tumor zone in the TRM direction. We estimated the possible margin distance using scatterplots and linear regression analyses, which also showed the estimated distance more than 5.5 mm. In conclusion, the p-Chk1 and p44/42 ERK may be potential candidates of molecular risk markers that may be related to the local recurrence after complete ESD, and a tumor-free distance of 5.5 mm is not enough for safety margin.

Breastfeeding importance and its therapeutic potential against SARS-CoV-2

During postnatal development, colostrum and breastmilk are sequentially the first sources of nutrition with protein components and bioactive molecules that confer protection and immunostimulatory function to the gut. Caseins, whey proteins, secretory immunoglobulin A (sIgA), mucins, tryptophan, and growth factors are among milk-borne elements that are directly important in the control of mucosa development and protection. Consequently, breastfeeding is associated with the low incidence of gastrointestinal inflammation and with the decrease in respiratory diseases during postnatal period. The novel coronavirus (SARS-CoV-2) binds to angiotensin II-converting enzyme (ACE2) on the cell membrane, allowing virus entrance, replication, and host commitment. ACE2 is expressed by different cell types, which include ciliated cells in the lungs and enterocytes in the intestine. Such cells are highly active in metabolism, as they internalize molecules to be processed and used by the organism. The disruption of ACE2 impairs leads to intestinal inflammation and decreased synthesis of serotonin, affecting motility. By reviewing the effects of SARS-CoV-2 in the gastrointestinal and respiratory tracts in infants, and gut responses to breastfeeding interruption, we suggest that it is important to maintain breastfeeding during SARS-CoV-2 infection, as it might be essential to protect newborns from gastrointestinal-associated disorders and relieve disease symptoms.

Comparison of MicroRNA Transcriptomes Reveals the Association between MiR-148a-3p Expression and Rumen Development in Goats

Simple Summary

In ruminants, the rumen epithelium plays an important role in nutrient absorption, metabolism and transport. MicroRNAs (miRNAs) have been reported to regulate the proliferation of diverse epithelial cells. In this study, we profiled the miRNA transcriptomes of goat rumens at four development stages and screened for candidate miRNAs related to rumen development. MiR-148a-3p was found to be highly expressed in the rumen tissues and induced the proliferation of GES-1 cells by targeting QKI. Our findings provide some insights into the functional roles of miRNAs in rumen growth and functional development in ruminants.

Abstract

The rumen is an important digestive organ of ruminants. From the fetal to adult stage, the morphology, structure and function of the rumen change significantly. However, the knowledge of the intrinsic genetic regulation of these changes is still limited. We previously reported a genome-wide expression profile of miRNAs in pre-natal goat rumens. In this study, we combined and analyzed the transcriptomes of rumen miRNAs during pre-natal (E60 and E135) and post-natal (D30 and D150) stages. A total of 66 differentially expressed miRNAs (DEMs) were identified in the rumen tissues from D30 and D150 goats. Of these, 17 DEMs were consistently highly expressed in the rumens at the pre-weaning stages (E60, E135 and D30), while down-regulated at D150. Noteworthy, annotation analysis revealed that the target genes regulated by the DEMs were mainly enriched in MAPK signaling pathway, Jak-STAT signaling pathway and Ras signaling pathway. Interestingly, the expression of miR-148a-3p was significantly high in the embryonic stage and down-regulated at D150. The potential binding sites of miR-148a-3p in the 3′-UTR of QKI were predicted by the TargetScan and verified by the dual luciferase report assay. The co-localization of miR-148a-3p and QKI through in situ hybridization was observed in the rumen tissues but not in the intestinal tracts. Moreover, the expression of miR-148a-3p in the epithelium was significantly higher than that in the other layers of the rumen, suggesting that miR-148a-3p is involved in the development of the rumen epithelial cells by targeting QKI. Subsequently, miR-148a-3p inhibitor was found to induce the proliferation of GES-1 cells. Taken together, our study identified DEMs involved in the development of the rumen and provides insights into the regulation mechanism of rumen development in goats.

Targeting epidermal growth factor-overexpressing triple-negative breast cancer by natural killer cells expressing a specific chimeric antigen receptor

OBJECTIVES

Traditional cancer therapy and regular immunotherapy are ineffective for treating triple-negative breast cancer (TNBC) patients. Recently, chimeric antigen receptor-engineered natural killer cells (CAR NK) have been applied to target several hormone receptors on different cancer cells to improve the efficacy of immunotherapy. Furthermore, epidermal growth factor receptor (EGFR) is a potential therapeutic target for TNBC. Here, we demonstrated that EGFR-specific CAR NK cells (EGFR-CAR NK cells) could be potentially used to treat patients with TNBC exhibiting enhanced EGFR expression.

MATERIALS AND METHODS

We investigated the cytotoxic effects of EGFR-CAR NK cells against TNBC cells in vitro and in vivo. The two types of EGFR-CAR NK cells were generated by transducing lentiviral vectors containing DNA sequences encoding the single-chain variable fragment (scFv) regions of the two anti-EGFR antibodies. The cytotoxic and anti-tumor effects of the two cell types were examined by performing cytokine release and cytotoxicity assays in vitro, and tumor growth assays in breast cancer cell line-derived xenograft (CLDX) and patient-derived xenograft (PDX) mouse models.

RESULTS

Both EGFR-CAR NK cell types were activated by TNBC cells exhibiting upregulated EGFR expression and specifically triggered the lysis of the TNBC cells in vitro. Furthermore, the two EGFR-CAR NK cell types inhibited CLDX and PDX tumors in mice.

CONCLUSIONS

This study suggested that treatment with EGFR-CAR NK cells could be a promising strategy for TNBC patients.

Immediate and Late Effects of Early Weaning on Rat Gastric Cell Differentiation

Background: Gastric glands grow and cells reach differentiation at weaning in rats. By considering that early weaning (EW) can affect the timing of development, we aimed to compare molecular and cellular markers of differentiation in pups and adults. Methods: Wistar rats were separated into suckling-control (S) and EW groups at 15 days. Stomachs were collected at 15, 18, and 60 days for RNA and protein extraction, and morphology. Results: After EW, the expression of genes involved in differentiation (Atp4b, Bhlha15 and Pgc) augmented (18 days), and Atp4b and Gif were high at 60 days. EW increased the number of zymogenic cells (ZC) in pups and adults and augmented mucous neck cells only at 18 days, whereas parietal and transition cells (TC) were unchanged. Conclusions: EW affected the gastric mucosa mostly in a transient manner as the changes in gene expression and distribution of differentiated cells that were detected in pups were not fully maintained in adults, except for the size of ZC population. We concluded that though most of EW effects were immediate, such nutritional change in the infancy might affect part of gastric digestive functions in a permanent manner, as some markers were kept unbalanced in the adulthood.

A Novel Role of Irbesartan in Gastroprotection against Indomethacin-Induced Gastric Injury in Rats: Targeting DDAH/ADMA and EGFR/ERK Signaling

The advent of angiotensin II type 1 receptor blockers (ARBs) as intriguing gastroprotective candidates and the superior pharmacokinetics and pharmacodynamics displayed by irbesartan compared to many other ARBs raised the interest to investigate its gastroprotective potential in a rat model of gastric injury. Irbesartan (50 mg/Kg) was orally administered to male Wistar rats once daily for 14 days; thereafter gastric injury was induced by indomethacin (60 mg/Kg, p.o). Irbesartan reduced gastric ulcer index, gastric acidity, and ameliorated indomethacin-induced gastric mucosal apoptotic and inflammatory aberrations, as demonstrated by hampering caspase-3, prostaglandin E₂ and tumor necrosis factor-alpha levels and cyclooxygenase-2 mRNA expression. This ARB increased mucosal dimethylarginine dimethylaminohydrolase-1 (DDAH-1) gene expression and decreased elevated levels of matrix metalloproteinase-9, asymmetric dimethylarginine (ADMA), epidermal growth factor receptor (EGFR) mRNA and phosphorylated extracellular signal-regulated kinase 1 and 2 (pERK1/2). Histopathological evaluation corroborated biochemical findings. Overall efficacy of irbesartan was comparable to ranitidine, the widely used H₂ receptor blocker. In conclusion, irbesartan exerts significant gastroprotection against indomethacin-induced mucosal damage via acid-inhibitory, anti-inflammatory, anti-apoptotic and extracellular matrix remodeling mechanisms that are probably mediated, at least partly, by down-regulating DDAH/ADMA and EGFR/ERK1/2 signaling.

Identification and Characterization of MicroRNAs in the Goat (Capra hircus) Rumen during Embryonic Development

The rumen is an important digestive organ in ruminants. Numerous regulatory factors including microRNAs (miRNAs) are involved in embryonic organ development. In the present study, miRNAs expressed in the rumens of goats (Capra hircus) and their potential roles in the pathways involved in rumen development were identified using high-throughput sequencing. Histological morphology revealed a distinct difference in each layer of rumen during the period from embryonic day 60 (E60) to embryonic day 135 (E135). We determined the expression profiles of miRNAs in the goat rumen, and identified 423 known miRNAs and 559 potentially novel miRNAs in the E60 and E135 embryonic rumen, respectively. Bioinformatics analysis annotated the 42 differentially expressed miRNAs and the top 10 most highly expressed miRNAs of the two libraries to 48 and 38 gene ontology categories, as well as to 168 and 71 Kyoto Encyclopedia of Genes and Genomes pathways, respectively. The expression patterns of eight randomly selected miRNAs were validated by stem-loop quantitative reverse transcription PCR, suggesting that the sequencing data were reliable. We profiled the genome-wide expression of rumen-expressed miRNAs at different prenatal stages of rumen tissues, revealing that a subset of miRNAs might play important roles in the formation of the rumen layers. Taken together, these findings will aid the investigation of dominant rumen-related miRNA sets and help understand the genetic control of rumen development in goats.

Corticosterone activity during early weaning reprograms molecular markers in rat gastric secretory cells

Gastric epithelial cells differentiate throughout the third postnatal week in rats, and become completely functional by weaning time. When suckling is interrupted by early weaning (EW), cell proliferation and differentiation change in the gastric mucosa, and regulatory mechanisms might involve corticosterone activity. Here we used EW and RU486 (glucocorticoid receptor antagonist) to investigate the roles of corticosterone on differentiation of mucous neck (MNC) and zymogenic cells (ZC) in rats, and to evaluate whether effects persisted in young adults. MNC give rise to ZC, and mucin 6, Mist1, pepsinogen a5 and pepsinogen C are produced to characterize these cells. We found that in pups, EW augmented the expression of mucins, Mist1 and pepsinogen C at mRNA and protein levels, and it changed the number of MNC and ZC. Corticosterone regulated pepsinogen C expression, and MNC and ZC distributions. Further, the changes on MNC population and pepsinogen C were maintained until early- adult life. Therefore, by using EW as a model for altered corticosterone activity in rats, we demonstrated that the differentiation of secretory epithelial cells is sensitive to the type of nutrient in the lumen. Moreover, this environmental perception activates corticosterone to change maturation and reprogram cellular functions in adulthood.

MOXIBUSTION ALLEVIATES GASTRIC PRECANCEROUS LESIONS IN RATS BY PROMOTING CELL APOPTOSIS AND INHIBITING PROLIFERATION-RELATED ONCOGENES

Background:

It is well known that gastric mucosa dysplasia and intestinal metaplasia are gastric precancerous lesions (GPL). Moxibustion treatment of Liangmen (ST21) and Zusanli (ST36) alleviated the inflammatory response and dysplasia of gastric mucosa in our previous study. The purpose of this study was to further examine the underlying mechanism of moxibustion treatment of ST21 and ST36 on GPL.

Materials and Methods:

Sixty SD rats were divided into five groups and rats with GPL were treated with either moxibustion (ST), moxibustion (Sham), or vitacoenzyme. B-cell lymphoma 2 (bcl-2), tumor protein p53 (P53) and cellular Myc (C-MYC), which are related to cell apoptosis, proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF), argyrophilic nucleolar organizer region proteins (Ag-NORs), which are associated with cell proliferation, and cell signaling proteins, nuclear factor kappa B (NF-κB), epidermal growth factor receptor (EGFR) and phosphorylated extracellular signal regulated kinase (p-ERK), were measured after moxibustion treatment.

Results:

Compared with Control group, gastric mucosa in GPL group showed abnormal mucosal proliferation and pathological mitotic figure, the mRNA expression of bcl-2, P53 and C-MYC increased significantly (P < 0.01), the protein expression of PCNA, VEGF, Ag-NORs and the activity of NF-κβ as well as EGFR/ERK signaling proteins also increased significantly (P < 0.01). Moxibustion treatment decreased gastric mucosal proliferation and pathological mitotic figure, down-regulated the mRNA expression of bcl-2, P53, C-MYC (P < 0.01), decreased the protein expression of PCNA, VEGF, Ag-NORs and the activity of NF-κβ as well as EGFR/ERK signaling proteins significantly (P < 0.01). But moxibustion treatment of Sham didn’t show the same effect on GPL.

Conclusion:

Moxibustion treatment inhibited cell apoptosis and reduced gastric mucosa dysplasia by inhibiting the expression of bcl-2, P53, C-MYC and decreased the activity of NF-κβ as well as EGFR/ERK signaling proteins.

Analyzing pERK Activation During Planarian Regeneration

Planarians are an ideal model in which to study stem cell-based regeneration. After amputation, planarian pluripotent stem cells surrounding the wound proliferate to produce the regenerative blastema, in which they differentiate into the missing tissues and structures. Recent independent studies in planarians have shown that Smed-egfr-3, a gene encoding a homologue of epidermal growth factor (EGF) receptors, and DjerkA, which encodes an extracellular signal-regulated kinase (ERK), may control cell differentiation and blastema growth. However, because these studies were carried in two different planarian species, the relationship between these two genes remains unclear. We have optimized anti-pERK immunostaining in Schmidtea mediterranea using the original protocol developed in Dugesia japonica. Both protocols are reported here as most laboratories worldwide work with one of these two species. Using this protocol we have determined that Smed-egfr-3 appears to be necessary for pERK activation during planarian regeneration.

Ghrelin and GHS-R in the rat gastric mucosa: Are they involved in regulation of growth during early weaning?

OBJECTIVES

Based on previous evidence showing that early weaning disturbs the ontogenesis of rat gastric glands, which are the major site of ghrelin synthesis, we investigated the distribution of ghrelin and its receptor (GHS-R) in the rat gastric epithelium during postnatal development and evaluated the effects of early weaning on their levels. Additionally, we studied the contribution of ghrelin to gastric growth during the abrupt nutrient transition.

METHODS

Wistar rats were submitted to early weaning at 15 d and suckling counterparts were taken as controls.

RESULTS

By running quantitative reverse transcription polymerase chain reaction, immunoblots, and immunohistochemistry, we detected a variation of ghrelin levels and an increase of expression and number of immunolabeled cells, 3 d after treatment (P < 0.05). Through confocal microscopy, we identified GHS-R in the neck region of the gland and did not observe changes in protein levels. Growth was evaluated after ghrelin antagonist ([D-Lys-3]-GHRP-6) administration, which reduced DNA synthesis index in early-weaned rats (P < 0.05) as determined by bromodeoxyuridine incorporation.

CONCLUSION

The present study demonstrated that ghrelin and GHS-R are distributed in gastric mucosa during the postnatal development, indicating that they can signal and function in epithelial cells. We concluded that early weaning increased ghrelin levels in the stomach, and it takes part of cell proliferation control that is essential for stomach growth. Therefore, among the many effects previously described for early weaning, this abrupt nutrient transition also changed ghrelin levels, which might represent an additional element in the complex mechanism that coordinates stomach development.

Transforming growth factor β1 increases p27 levels via synthesis and degradation mechanisms in the hyperproliferative gastric epithelium in rats

Throughout postnatal development, the gastric epithelium expresses Transforming Growth Factor beta1 (TGFβ1), but it is also exposed to luminal peptides that are part of milk. During suckling period, fasting promotes the withdrawal of milk-born molecules while it stimulates gastric epithelial cell proliferation. Such response can be reversed by exogenous TGFβ1, as it directly affects cell cycle through the regulation of p27 levels. We used fasting condition to induce the hyperproliferation of gastric epithelial cells in 14-day-old Wistar rats, and evaluated the effects of TGFβ1 gavage on p27 expression, phosphorylation at threonine 187 (phospho-p27^Thr187) and degradation. p27 protein level was reduced during fasting when compared to suckling counterparts, while phospho-p27^Thr187/p27 ratio was increased. TGFβ1 gavage reversed this response, which was confirmed through immunostaining. By using a neutralizing antibody against TGFβ1, we found that it restored the p27 and phosphorylation levels detected during fasting, indicating the specific role of the growth factor. We noted that neither fasting nor TGFβ1 changed p27 expression, but after cycloheximide administration, we observed that protein synthesis was influenced by TGFβ1. Next, we evaluated the capacity of the gastric mucosa to degrade p27 and we recorded a higher concentration of the remaining protein in pups treated with TGFβ1, suggesting augmented stability under this condition. Thus, we showed for the first time that luminal TGFβ1 increased p27 levels in the rat gastric mucosa by up- regulating translation and reducing protein degradation. We concluded that such mechanisms might be used by rapidly proliferating cells to respond to milk-born TGFβ1 and food restriction.

Electroacupuncture promotes neural cell proliferation in vivo through activation of the ERK1/2 signaling pathway

The aim of this study was to investigate the effect of electroacupuncture (EA) on cell proliferation and its molecular mechanisms. Sixty rats were randomly divided into 5 groups: sham operation control (SC), ischemia control (IC), EA, EA and DMSO injection (ED), EA and U0126 injection (EU). All the groups, with the exception of SC, underwent middle cerebral artery occlusion (MCAO), and DMSO or U0126 was injected into the rat in the ED or EU group 30 min prior to MCAO. Cell proliferation was evaluated by proliferating cell nuclear antigen (PCNA) immunostaining. The changes of cell cycle proteins (cyclin D1, CDK4, cyclin E, CDK2, p21 and p27) and the ERK1/2 pathway activation were examined by RT-PCR and western blot analysis. The results showed that the positive cell numbers of PCNA immunostaining in the EA and ED groups were more than those in the IC group (P<0.05). The mRNA and protein levels of p21 or p27 were obviously increased, however, the mRNA and protein levels of cyclin D1, CDK4, cyclin E and CDK2 were reduced in the IC and EU groups. The findings suggested that EA activates the ERK1/2 signaling pathway to protect brain injury during cerebral ischemia. However, this positive effect of EA can be blocked by U0126.

MAPK signaling pathway regulates p27 phosphorylation at threonin 187 as part of the mechanism triggered by early-weaning to induce cell proliferation in rat gastric mucosa

During rat postnatal development, gastric cell proliferation and differentiation depend on many elements, which include dietary pattern, hormones, growth factors and their signaling pathways. Among them, EGFR activity is increased through MAPK and Src cascades in response to early weaning that represents the abrupt transition from milk to solid food. We herein investigated the direct involvement of ERK pathway in the control of cell cycle progression during early weaning, and studied the specific role of p27. At 15 days, Wistar rats were separated from dams, fed with powdered chow and daily injected with PD98059 (MEK inhibitor, 300 µg/kg) or 0.5% DMSO (control). By using HE staining and immunohistochemistry for PCNA, we respectively detected mitotic (MI) and proliferative (PI) indices in 18-day-old pups, and observed that both were reduced by PD98059. As cell cycle-related proteins (cyclin E, CDK2, cyclin D1, CDK4, p21 and p27) are involved in proliferative regulation, we compared samples obtained at 17 days in the morning (17 d) and evening (17.5 d). We found that they were not altered after ERK inhibition, but cyclin D1, p21 and p27 levels changed throughout the day in the control group. As p27 activity depends on its integrity, we studied p27 phosphorylation (threonin 187), and observed that ERK inhibition reduced this process. We suggest that MAPK pathway interferes in the regulation of p27 function in the gastric mucosa during early weaning, possibly by controlling its degradation, and altogether this mechanism might contribute to the increase of epithelial proliferation at this condition.

The hyaluronic acid receptor CD44 coordinates normal and metaplastic gastric epithelial progenitor cell proliferation

The stem cell in the isthmus of gastric units continually replenishes the epithelium. Atrophy of acid-secreting parietal cells (PCs) frequently occurs during infection with Helicobacter pylori, predisposing patients to cancer. Atrophy causes increased proliferation of stem cells, yet little is known about how this process is regulated. Here we show that CD44 labels a population of small, undifferentiated cells in the gastric unit isthmus where stem cells are known to reside. Loss of CD44 in vivo results in decreased proliferation of the gastric epithelium. When we induce PC atrophy by Helicobacter infection or tamoxifen treatment, this CD44(+) population expands from the isthmus toward the base of the unit. CD44 blockade during PC atrophy abrogates the expansion. We find that CD44 binds STAT3, and inhibition of either CD44 or STAT3 signaling causes decreased proliferation. Atrophy-induced CD44 expansion depends on pERK, which labels isthmal cells in mice and humans. Our studies delineate an in vivo signaling pathway, ERK → CD44 → STAT3, that regulates normal and atrophy-induced gastric stem/progenitor-cell proliferation. We further show that we can intervene pharmacologically at each signaling step in vivo to modulate proliferation.

MAPKs and signal transduction in the control of gastrointestinal epithelial cell proliferation and differentiation

Mitogen-activated protein kinase (MAPK) pathways are activated by several stimuli and transduce the signal inside cells, generating diverse responses including cell proliferation, differentiation, migration and apoptosis. Each MAPK cascade comprises a series of molecules, and regulation takes place at different levels. They communicate with each other and with additional pathways, creating a signaling network that is important for cell fate determination. In this review, we focus on ERK, JNK, p38 and ERK5, the major MAPKs, and their interactions with PI3K-Akt, TGFβ/Smad and Wnt/β-catenin pathways. More importantly, we describe how MAPKs regulate cell proliferation and differentiation in the rapidly renewing epithelia that lines the gastrointestinal tract and, finally, we highlight the recent findings on nutritional aspects that affect MAPK transduction cascades.

Independent of ErbB1 gene copy number, EGF stimulates migration but is not associated with cell proliferation in non-small cell lung cancer

Background

Lung cancer often exhibits molecular changes, such as the overexpression of the ErbB1 gene. ErbB1 encodes epidermal growth factor receptor (EGFR), a tyrosine kinase receptor, involved mainly in cell proliferation and survival. EGFR overexpression has been associated with more aggressive disease, poor prognosis, low survival rate and low response to therapy. ErbB1 amplification and mutation are associated with tumor development and are implicated in ineffective treatment. The aim of the present study was to investigate whether the ErbB1 copy number affects EGFR expression, cell proliferation or cell migration by comparing two different cell lines.

Methods

The copies of ErbB1 gene was evaluated by FISH. Immunofluorescence and Western blotting were performed to determine location and expression of proteins mentioned in the present study. Proliferation was studied by flow cytometry and cell migration by wound healing assay and time lapse.

Results

We investigated the activation and function of EGFR in the A549 and HK2 lung cancer cell lines, which contain 3 and 6 copies of ErbB1, respectively. The expression of EGFR was lower in the HK2 cell line. EGFR was activated after stimulation with EGF in both cell lines, but this activation did not promote differences in cellular proliferation when compared to control cells. Inhibiting EGFR with AG1478 did not modify cellular proliferation, confirming previous data. However, we observed morphological alterations, changes in microfilament organization and increased cell migration upon EGF stimulation. However, these effects did not seem to be consequence of an epithelial-mesenchymal transition.

Conclusion

EGFR expression did not appear to be associated to the ErbB1 gene copy number, and neither of these aspects appeared to affect cell proliferation. However, EGFR activation by EGF resulted in cell migration stimulation in both cell lines.

EBP50 inhibits EGF-induced breast cancer cell proliferation by blocking EGFR phosphorylation

Ezrin-radixin-moesin-binding phosphoprotein-50 (EBP50) suppresses breast cancer cell proliferation, potentially through its regulatory effect on epidermal growth factor receptor (EGFR) signaling, although the mechanism by which this occurs remains unknown. Thus in our studies, we aimed to determine the effect of EBP50 expression on EGF-induced cell proliferation and activation of EGFR signaling in the breast cancer cell lines, MDA-MB-231 and MCF-7. In MDA-MB-231 cells, which express low levels of EBP50, EBP50 overexpression inhibited EGF-induced cell proliferation, ERK1/2 and AKT phosphorylation. In MCF-7 cells, which express high levels of EBP50, EBP50 knockdown promoted EGF-induced cell proliferation, ERK1/2 and AKT phosphorylation. Knockdown of EBP50 in EBP50-overexpressed MDA-MB-231 cells abrogated the inhibitory effect of EBP50 on EGF-stimulated ERK1/2 phosphorylation and restoration of EBP50 expression in EBP50-knockdown MCF-7 cells rescued the inhibition of EBP50 on EGF-stimulated ERK1/2 phosphorylation, further confirming that the activation of EGF-induced downstream molecules could be specifically inhibited by EBP50 expression. Since EGFR signaling was triggered by EGF ligands via EGFR phosphorylation, we further detected the phosphorylation status of EGFR in the presence or absence of EBP50 expression. Overexpression of EBP50 in MDA-MB-231 cells inhibited EGF-stimulated EGFR phosphorylation, whereas knockdown of EBP50 in MCF-7 cells enhanced EGF-stimulated EGFR phosphorylation. Meanwhile, total expression levels of EGFR were unaffected during EGF stimulation. Taken together, our data shows that EBP50 can suppress EGF-induced proliferation of breast cancer cells by inhibiting EGFR phosphorylation and blocking EGFR downstream signaling in breast cancer cells. These results provide further insight into the molecular mechanism by which EBP50 regulates the development and progression of breast cancer.

Enhanced wound healing by recombinant Escherichia coli Nissle 1917 via human epidermal growth factor receptor in human intestinal epithelial cells: therapeutic implication using recombinant probiotics

The gastrointestinal mucosa has a remarkable ability to repair damage with the support of epidermal growth factor (EGF), which stimulates epithelial migration and proliferative reepithelialization. For the treatment of mucosal injuries, it is important to develop efficient methods for the localized delivery of mucoactive biotherapeutics. The basic idea in the present study came from the assumption that an intestinal probiotic vehicle can carry and deliver key recombinant medicinal proteins to the injured epithelial target in patients with intestinal ulcerative diseases, including inflammatory bowel disease. The study was focused on the use of the safe probiotic E. coli Nissle 1917, which was constructed to secrete human EGF in conjunction with the lipase ABC transporter recognition domain (LARD). Using the in vitro physically wounded monolayer model, ABC transporter-mediated EGF secretion by probiotic E. coli Nissle 1917 was demonstrated to enhance the wound-healing migration of human enterocytes. Moreover, the epithelial wound closure was dependent on EGF receptor-linked activation, which exclusively involved the subsequent signaling pathway of the mitogen-activated protein kinase kinase (MEK) extracellular-related kinases 1 and 2 (ERK1/2). In particular, the migrating frontier of the wounded edge displayed the strongest EGF receptor-linked signaling activation in the presence of the recombinant probiotic. The present study provides a basis for the clinical application of human recombinant biotherapeutics via an efficient, safe probiotic vehicle.