Comprehensive analysis of miRNA-mRNA regulatory pairs associated with colorectal cancer and the role in tumor immunity.

BACKGROUND: MicroRNA (miRNA) which can act as post-transcriptional regulators of mRNAs via base-pairing with complementary sequences within mRNAs is involved in processes of the complex interaction between immune system and tumors. In this research, we elucidated the profiles of miRNAs and target mRNAs expression and their associations with the phenotypic hallmarks of colorectal cancers (CRC) by integrating transcriptomic, immunophenotype, methylation, mutation and survival data. RESULTS: We conducted the analysis of differential miRNA/mRNA expression profile by GEO, TCGA and GTEx databases and the correlation between miRNA and targeted mRNA by miRTarBase and TarBase. Then we detected using qRT-PCR and validated the diagnostic value of miRNA-mRNA regulator pairs by the ROC, calibration curve and DCA. Phenotypic hallmarks of regulatory pairs including tumor-infiltrating lymphocytes, tumor microenvironment, tumor mutation burden, global methylation and gene mutation were also described. The expression levels of miRNAs and target mRNAs were detected in 80 paired colon tissue samples. Ultimately, we picked up two pivotal regulatory pairs (miR-139-5p/ STC1 and miR-20a-5p/ FGL2) and verified the diagnostic value of the complex model which is the combination of 4 signatures above-mentioned in 3 testing GEO datasets and an external validation cohort. CONCLUSIONS: We found that 2 miRNAs by targeting 2 metastasis-related mRNAs were correlated with tumor-infiltrating macrophages, HRAS, and BRAF gene mutation status. Our results established the diagnostic model containing 2 miRNAs and their respective targeted mRNAs to distinguish CRCs and normal controls and displayed their complex roles in CRC pathogenesis especially tumor immunity.

[Processing Magnoliae Officinalis Cortex with ginger juice: process optimization based on AHP-CRITIC weighting method and composition changes after processing].

The weight coefficients of appearance traits, extract yield of standard decoction, and total content of honokiol and magnolol were determined by analytic hierarchy process(AHP), criteria importance though intercrieria correlation(CRITIC), and AHP-CRITIC weighting method, and the comprehensive scores were calculated. The effects of ginger juice dosage, moistening time, proces-sing temperature, and processing time on the quality of Magnoliae Officinalis Cortex(MOC) were investigated, and Box-Behnken design was employed to optimize the process parameters. To reveal the processing mechanism, MOC, ginger juice-processed Magnoliae Officinalis Cortex(GMOC), and water-processed Magnoliae Officinalis Cortex(WMOC) were compared. The results showed that the weight coefficients of the appearance traits, extract yield of standard decoction, and total content of honokiol and magnolol determined by AHP-CRITIC weighting method were 0.134, 0.287, and 0.579, respectively. The optimal processing parameters of GMOC were ginger juice dosage of 8%, moistening time of 120 min, and processing at 100 ℃ for 7 min. The content of syringoside and magnolflorine in MOC decreased after processing, and the content of honokiol and magnolol followed the trend of GMOC>MOC>WMOC, which suggested that the change in clinical efficacy of MOC after processing was associated with the changes of chemical composition. The optimized processing technology is stable and feasible and provides references for the modern production and processing of MOC.

Integrative analysis of negatively regulated miRNA-mRNA axes for esophageal squamous cell carcinoma.

BACKGROUND: MicroRNAs regulating mRNA expression by targeting at mRNAs is known constructive in tumor occurrence, immune escape, and metastasis. OBJECTIVE: This research aims at finding negatively regulatory miRNA-mRNA pairs in esophageal squamous cell carcinoma (ESCC). METHODS: GENE expression data of The Cancer Genome Atlas (TCGA) and GEO database were employed in differently expressed RNA and miRNA (DE-miRNAs/DE-mRNAs) screening. Function analysis was conducted with DAVID-mirPath. MiRNA-mRNA axes were identified by MiRTarBase and TarBase and verified in esophageal specimen by real-time reverse transcription polymerase chain reaction (RT-qPCR). Receiver operation characteristic (ROC) curve and Decision Curve Analysis (DCA) were applied in miRNA-mRNA pairs predictive value estimation. Interactions between miRNA-mRNA regulatory pairs and immune features were analyzed using CIBERSORT. RESULTS: Combining TCGA database, 4 miRNA and 10 mRNA GEO datasets, totally 26 DE-miRNAs (13 up and 13 down) and 114 DE-mRNAs (64 up and 50 down) were considered significant. MiRTarBase and TarBase identified 37 reverse regulation miRNA-mRNA pairs, 14 of which had been observed in esophageal tissue or cell line. Through analysis of RT-qPCR outcome, miR-106b-5p/KIAA0232 signature was chosen as characteristic pair of ESCC. ROC and DCA verified the predictive value of model containing miRNA-mRNA axis in ESCC. Via affecting mast cells, miR-106b-5p/KIAA0232 may contribute to tumor microenvironment. CONCLUSIONS: The diagnostic model of miRNA-mRNA pair in ESCC was established. Their complex role in ESCC pathogenesis especially tumor immunity was partly disclosed.

miR-338-3p acts as a tumor suppressor in lung squamous cell carcinoma by targeting FGFR2/FRS2.

Background: Lung cancer refers to the occurrence of malignant tumors in the lung, and squamous cell carcinoma is one of the most common pathological types of non-small cell lung cancer. Studies have shown that microRNAs (miRNAs) play an important role in the occurrence, development, early diagnosis, and treatment of lung cancer. This study aimed to explore the role and possible mechanism of MicroRNA-338-3p (miR-338-3p) in lung squamous cell carcinoma (LUSC). Method: In this study, we compared 238 LUSC patients with relatively high miR-338-3p expression levels with 238 miR-338-3p expression levels in The Cancer Genome Atlas (TCGA)-LUSC dataset using first-line gene set enrichment analysis (GSEA). Second, the mRNA expression of miR-338-3p, FGFR2, and fibroblast growth factor receptor substrate 2 (FRS2) in 30 lung cancers and adjacent lung tissues was detected using quantitative real-time polymerase chain reaction (qRT-PCR). Finally, in vitro experiments were conducted, whereby the expression levels of miR-338-3p in lung cancer cells (H1703, SKMES1, H2170, H520) and normal lung epithelial cells (16HBE) were detected using qRT-PCR. miR-338-3p was overexpressed in lung cancer cells (H1703), and the cell proliferation (cell counting kit-8 [CCK8] assay), colony formation, cell apoptosis, cell cycle (BD-FACSVerse assay, Becton Dickinson, Bedford, MA, USA), cell invasion, and migration (Transwell assay, Thermo Fischer Corporation, Waltham, MA, USA) were detected. Results: We found that the expression of miR-338-3p was significantly reduced in LUSC tissues (p â€‹< â€‹0.001) and cancer cell lines (P < 0.01), and miR-338-3p was significantly negatively correlated with the expression of FGFR2 (P < 0.001) and FRS2 (P < 0.01). Furthermore, overexpression of miR-338-3p inhibited proliferation (P < 0.001), migration, and invasion (P < 0.001) of LUSC cell lines and increased apoptosis in the G1 phase (P < 0.001) and cell cycle arrest (P < 0.05). Conclusions: Our study demonstrates that miR-338-3p inhibits tumor cell proliferation and migration by targeting FGFR2 and FRS2 in LUSC. We believe that miR-338-3p may be a promising target for the treatment of LUSC.

Analysis of aberrant miRNA-mRNA interaction networks in prostate cancer to conjecture its molecular mechanisms.

BACKGROUND: MicroRNAs (miRNAs) capable of post-transcriptionally regulating mRNA expression are essential to tumor occurrence and progression. OBJECTIVE: This study aims to find negatively regulatory miRNA-mRNA pairs in prostate adenocarcinoma (PRAD). METHODS: Combining The Cancer Genome Atlas (TCGA) RNA-Seq data with Gene Expression Omnibus (GEO) mRNA/miRNA expression profiles, differently expressed miRNA/mRNA (DE-miRNAs/DE-mRNAs) were identified. MiRNA-mRNA pairs were screened by miRTarBase and TarBase, databases collecting experimentally confirmed miRNA-mRNA pairs, and verified in 30 paired prostate specimens by real-time reverse transcription polymerase chain reaction (RT-qPCR). The diagnostic values of miRNA-mRNA pairs were measured by receiver operation characteristic (ROC) curve and Decision Curve Analysis (DCA). DAVID-mirPath database and Connectivity Map were employed in GO/KEGG analysis and compounds research. Interactions between miRNA-mRNA pairs and phenotypic features were analyzed with correlation heatmap in hiplot. RESULTS: Based on TCGA RNA-Seq data, 22 miRNA and 14 mRNA GEO datasets, 67 (20 down and 47 up) miRNAs and 351 (139 up and 212 down) mRNAs were selected. After screening from 2 databases, 8 miRNA (up)-mRNA (down) and 7 miRNA (down)-mRNA (up) pairs were identified with Pearson's correlation in TCGA. By external validation, miR-221-3p (down)/GALNT3 (up) and miR-20a-5p (up)/FRMD6 (down) were chosen. The model combing 4 signatures possessed better diagnostic value. These two miRNA-mRNA pairs were significantly connected with immune cells fraction and tumor immune microenvironment. CONCLUSIONS: The diagnostic model containing 2 negatively regulatory miRNA-mRNA pairs was established to distinguish PRADs from normal controls.

Identify miRNA-mRNA regulation pairs to explore potential pathogenesis of lung adenocarcinoma.

PURPOSE: MicroRNA (miRNA) function via base-pairing with complementary sequences within mRNA molecules. This study aims to identify critical miRNA-mRNA regulation pairs contributing to lung adenocarcinoma (LUAD) pathogenesis. PATIENTS AND METHODS: MiRNA and mRNA microarray and RNA-sequencing datasets were downloaded from gene expression omnibus (GEO) and the cancer genome atlas (TCGA) databases. Differential miRNAs (DE-miRNAs) and mRNAs (DE-mRNAs) were screened by the GEO2R tool and R packages. DAVID, DIANA, and Hiplot tools were used to perform gene enrichment analysis. The pairs of miRNA-mRNA were screened from the experimentally validated miRNA-target interactions databases (miRTarBase and TarBase). External validation was carried out in 30 pairs of LUAD tissues by quantitative reverse transcription and polymerase chain reaction (qRT-PCR). The diagnostic value of the miRNA-mRNA regulation pairs was evaluated by receiver operating characteristic curve (ROC) and decision curve analysis (DCA). Biological function assay was were also performed to confirm the function of miRNA-mRNA axis in LUAD progression. The study also performed the clinical, survival and tumor-associated phenotypic analysis of miRNA-mRNA pairs. RESULTS: A total of 7 miRNA and 13 mRNA expression datasets from GEO were analyzed, and 11 DE-miRNAs (5 down-regulated and 6 up-regulated in LUAD tissues) and 128 DE-mRNAs (30 up-regulated and 98 down-regulated in LUAD tissues) were identified. The pairs of miR-1-3p(down) and CENPF(up) and miR-126-5p(down) and UGT8(up) were verified in the external validation cohort (30 LUAD vs. 30 NC) using qRT-PCR. Areas under the ROC curve of the two miRNA-mRNA regulation pairs panel were 0.973 in TCGA-LUAD and 0.771 in the external validation. The DCA also showed that the miRNA-mRNA regulation pairs had an excellent diagnostic performance distinguishing LUAD from normal controls. The expression of the regulation pairs is different in different ages, TNM stages, and gender. The overexpression of miR-1-3p and miR-126-5p significantly inhibited the proliferation and migration of LUAD cells. Correlation analysis showed that CENPF correlated with prognosis and tumor immunity. CONCLUSIONS: The research identified potential miRNA-mRNA regulation pairs, providing a new idea for exploring the genesis and development of LUAD.

Construction of the miRNA-mRNA Regulatory Networks and Explore Their Role in the Development of Lung Squamous Cell Carcinoma.

Purpose: MicroRNA (miRNA) binds to target mRNA and inhibit post-transcriptional gene expression. It plays an essential role in regulating gene expression, cell cycle, and biological development. This study aims to identify potential miRNA-mRNA regulatory networks that contribute to the pathogenesis of lung squamous cell carcinoma (LUSC). Patients and Methods: MiRNA microarray and RNA-Seq datasets were obtained from the gene expression omnibus (GEO) databases, the cancer genome atlas (TCGA), miRcancer, and dbDEMC. The GEO2R tool, "limma" and "DEseq" R packages were used to perform differential expression analysis. Gene enrichment analysis was conducted using the DAVID, DIANA, and Hiplot tools. The miRNA-mRNA regulatory networks were screened from the experimentally validated miRNA-target interactions databases (miRTarBase and TarBase). External validation was carried out in 30 pairs of LUSC tissues by Real-Time Quantitative Reverse Transcription PCR (qRT-PCR). Receiver operating characteristic curve (ROC) and decision curve analysis (DCA) were conducted to evaluate the diagnostic value. Clinical, survival and phenotypic analysis of miRNA-mRNA regulatory networks were further explored. Results: We screened 5 miRNA and 10 mRNA expression datasets from GEO and identified 7 DE-miRNAs and 270 DE-mRNAs. After databases screening and correlation analysis, four pairs of miRNA-mRNA regulatory networks were screened out. The miRNA-mRNA network of miR-205-5p (up) and PTPRM (down) was validated in 30 pairs of LUSC tissues. MiR-205-5p and PTPRM have good diagnostic efficacy and are expressed differently in different clinical features and are related to tumor immunity. Conclusion: The research identified a potential miRNA-mRNA regulatory network, providing a new way to explore the genesis and development of LUSC.

Comprehensive analysis of negatively correlated miRNA-mRNA regulatory pairs associated with microsatellite instability in colorectal cancer.

BACKGROUND: Several studies have demonstrated that microRNAs (miRNAs) and target mRNAs are associated with different frequencies of microsatellite instability. OBJECTIVE: The study aimed to elucidate the profiles of miRNAs and target mRNAs expression and their associations with the phenotypic hallmarks of microsatellite instability in colorectal cancers (CRC) by integrating transcriptomic, immunophenotype, methylation, mutation, and survival data. METHODS: Differentially expressed miRNAs (DEmiRNAs) and mRNAs (DEmRNAs) were screened out and then the miRNA-mRNA regulatory pairs were identified through two databases. We verified that the expression levels were detected in 40 microsatellite instable (MSI) and 40 microsatellite stable (MSS) CRC samples and used the logistic regression and the Cox regression method to evaluate the diagnostic and prognostic value of negative regulatory pairs respectively. RESULTS: The best diagnostic model that combines miR-31-5p, PLAGL2, miR-361-5p, and RAB27B, which were associated with immune microenvironment, tumor mutation burden (TMB), and overall DNA methylation, could significantly predict microsatellite instability in colon tissues. MiR-31-5p and RAB27B could also predict the overall survival of MSS CRCs. CONCLUSION: This study generated a predictive model of the combination of miRNAs and mRNAs to distinguish MSI versus MSS CRCs and elaborated their potential molecular mechanisms and biological functions.

Discrimination between raw and ginger juice processed Magnoliae officinalis cortex based on HPLC and Heracles NEO ultra-fast gas phase electronic nose.

INTRODUCTION: Magnoliae officinalis cortex (MOC), a traditional Chinese medicine, has been used in treating gastrointestinal diseases since ancient time. According to the Chinese Pharmacopoeia, it includes two kinds of decoction pieces, raw and ginger juice processed Magnoliae officinalis cortex (RMOC and GMOC). OBJECTIVE: The aim of this paper was to study the differences between non-volatile and volatile components in RMOC and GMOC. METHODS: The non-volatile components were detected by HPLC fingerprinting coupled with content determination (syringin, magnoflorine, honokiol and magnolol). Meanwhile, their odor information was obtained using a Heracles NEO ultra-fast gas phase electronic nose to conduct radar fingerprint analysis, principal component analysis and discriminant factor analysis, and the volatile components were analyzed qualitatively by the Kovats retention index and the AroChemBase database. RESULTS: The HPLC fingerprints were established and 20 common peaks were found in all chromatograms with similarity values of more than 0.900. The content determination results showed that the contents of syringin and magnoflorine decreased, while the contents of honokiol and magnolol increased in GMOC. By the gas phase electronic nose, the two decoction pieces could be distinguished obviously and 16 possible compounds were identified. Among them, the relative contents of (-)-α-pinene and ß-pinene increased, while ß-phellandrene and (+)-limonene levels decreased. CONCLUSION: The results suggested that honokiol, magnolol, (-)-α-pinene and ß-pinene might be the main substances which could enhance the harmonizing effect on the stomach. Moreover, this paper could lay a foundation for exploring the processing mechanism of MOC and provide a novel method for the research of other traditional Chinese medicine with strong aroma.

Global analysis of miRNA-mRNA regulation pair in bladder cancer.

PURPOSE: MicroRNA (miRNA) is a class of short non-coding RNA molecules that functions in RNA silencing and post-transcriptional regulation of gene expression. This study aims to identify critical miRNA-mRNA regulation pairs contributing to bladder cancer (BLCA) pathogenesis. PATIENTS AND METHODS: MiRNA and mRNA microarray and RNA-sequencing datasets were downloaded from gene expression omnibus (GEO) and the cancer genome atlas (TCGA) databases. The tool of GEO2R and R packages were used to screen differential miRNAs (DE-miRNAs) and mRNAs (DE-mRNAs) and DAVID, DIANA, and Hiplot tools were used to perform gene enrichment analysis. The miRNA-mRNA regulation pair were screened from the experimentally validated miRNA-target interactions databases (miRTarbase and TarBase). Twenty-eight pairs of BLCA tissues were used to further verify the screened DE-miRNAs and DE-mRNAs by quantitative reverse transcription and polymerase chain reaction (qRT-PCR). The diagnostic value of the miRNA-mRNA regulation pairs was evaluated by receiver operating characteristic curve (ROC) and decision curve analysis (DCA). The correlation analysis between the selected miRNA-mRNAs regulation pair and clinical, survival and tumor-related phenotypes was performed in this study. RESULTS: After miRTarBase, the analysis of 2 miRNA datasets, 6 mRNA datasets, and TCGA-BLCA dataset, a total of 13 miRNAs (5 downregulated and 8 upregulated in BLCA tissues) and 181 mRNAs (72 upregulated and 109 downregulated in BLCA tissues) were screened out. The pairs of miR-17-5p (upregulated in BLCA tissues) and TGFBR2 (downregulated in BLCA tissues) were verified in the external validation cohort (28 BLCA vs. 28 NC) using qRT-PCR. Areas under the ROC curve of the miRNA-mRNA regulation pair panel were 0.929 (95% CI: 0.885-0.972, p < 0.0001) in TCGA-BLCA and 0.767 (95% CI: 0.643-0.891, p = 0.001) in the external validation. The DCA also showed that the miRNA-mRNA regulation pairs had an excellent diagnostic performance distinguishing BLCA from normal controls. Correlation analysis showed that miR-17-5p and TGFBR2 correlated with tumor immunity. CONCLUSIONS: The research identified potential miRNA-mRNA regulation pairs, providing a new idea for exploring the genesis and development of BLCA.

MicroRNA expression profile in serum reveals novel diagnostic biomarkers for endometrial cancer.

PURPOSE: Circulating microRNAs (miRNAs) prove to be promising diagnostic biomarkers for various cancers, including endometrial cancer (EC). The present study aims to identify serum microRNAs that can serve as potential biomarkers for EC diagnosis. PATIENTS AND METHODS: A total of 92 EC and 102 normal control (NC) serum samples were analyzed using quantitative real-time polymerase chain reaction (qRT-PCR) in this four-phase experiment. The logistic regression method was used to construct a diagnostic model based on the differentially expressed miRNAs in serum. The receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic value. To further validate the diagnostic capacity of the identified signature, the 6-miRNA marker was compared with previously reported biomarkers and verified in three public datasets. In addition, the expression characteristics of the identified miRNAs were further explored in tissue and serum exosomes samples. RESULTS: Six miRNAs (miR-143-3p, miR-195-5p, miR-20b-5p, miR-204-5p, miR-423-3p, and miR-484) were significantly overexpressed in the serum of EC compared with NCs. Areas under the ROC of the 6-miRNA signatures were 0.748, 0.833, and 0.967 for the training, testing, and the external validation phases, respectively. The identified signature has a very stable diagnostic performance in the large cohorts of three public datasets. Compared with previously identified miRNA biomarkers, the 6-miRNA signature in the present study has superior performance in diagnosing EC. Moreover, the expression of miR-143-3p and miR-195-5p in tissues and the expression of miR-20b-5p in serum exosomes were consistent with those in serum. CONCLUSIONS: We established a 6-miRNA signature in serum and they could function as potential non-invasive biomarker for EC diagnosis.

MicroRNA panel in serum reveals novel diagnostic biomarkers for prostate cancer.

PURPOSE: MicroRNAs (miRNAs), which could be stably preserved and detected in serum or plasma, could act as biomarkers in cancer diagnosis. Prostate cancer is the second cancer in males for incidence. This study aimed to establish a miRNA panel in peripheral serum which could act as a non-invasive biomarker helping diagnosing PC. METHODS: A total of 86 PC patients and 86 normal control serum samples were analyzed through a four-stage experimental process using quantitative real-time polymerase chain reaction. Logistic regression method was used to construct a diagnostic model based on the differentially expressed miRNAs in serum. Receiver operating characteristic curves were constructed to evaluate the diagnostic accuracy. We also compared the 3-miRNA panel with previously reported biomarkers and verified in four public datasets. In addition, the expression characteristics of the identified miRNAs were further explored in tissue and serum exosomes samples. RESULTS: We identified a 3-miRNA signature including up-regulated miR-146a-5p, miR-24-3p and miR-93-5p for PC detection. Areas under the receiver operating characteristic curve of the 3-miRNA panel for the training, testing and external validation phase were 0.819, 0.831 and 0.814, respectively. The identified signature has a very stable diagnostic performance in the large cohorts of four public datasets. Compared with previously identified miRNA biomarkers, the 3-miRNA signature in this study has superior performance in diagnosing PC. What's more, the expression level of miR-93-5p was also elevated in exosomes from PC samples. However, in PC tissues, none of the three miRNAs showed significantly dysregulated expression. CONCLUSIONS: We established a three-miRNA panel (miR-146a-5p, miR-24-3p and miR-93-5p) in peripheral serum which could act as a non-invasive biomarker helping diagnosing PC.

Three plasma-based microRNAs as potent diagnostic biomarkers for endometrial cancer.

BACKGROUND: MicroRNAs (miRNAs), with noticeable stability and unique expression pattern in plasma of patients with various diseases, are powerful non-invasive biomarkers for cancer detection including endometrial cancer (EC). OBJECTIVE: The objective of this study was to identify promising miRNA biomarkers in plasma to assist the clinical screening of EC. METHODS: A total of 93 EC and 79 normal control (NC) plasma samples were analyzed using Quantitative Real-time Polymerase Chain Reaction (qRT-PCR) in this four-stage experiment. The receiver operating characteristic curve (ROC) analysis was conducted to evaluate the diagnostic value. Additionally, the expression features of the identified miRNAs were further explored in tissues and plasma exosomes samples. RESULTS: The expression of miR-142-3p, miR-146a-5p, and miR-151a-5p was significantly overexpressed in the plasma of EC patients compared with NCs. Areas under the ROC curve of the 3-miRNA signature were 0.729, 0.751, and 0.789 for the training, testing, and external validation phases, respectively. The diagnostic performance of the identified signature proved to be stable in the three public datasets and superior to the other miRNA biomarkers in EC diagnosis. Moreover, the expression of miR-151a-5p was significantly elevated in EC plasma exosomes. CONCLUSIONS: A signature consisting of 3 plasma miRNAs was identified and showed potential for the non-invasive diagnosis of EC.

Electron density measurement using a partially covered hairpin resonator in an inductively coupled plasma.

Hairpin probes are used to determine electron densities via measuring the shift of the resonant frequency of the probe structure when immersed in a plasma. This manuscript presents new developments in hairpin probe hardware and theory that have enabled measurements in a high electron density plasma, up to approximately 1012 cm-3, corresponding to a plasma frequency of about 9 GHz. Hardware developments include the use of both quarter-wavelength and three-quarter-wavelength partially covered hairpin probes in a transmission mode together with an easily reproducible implementation of the associated microwave electronics using commercial off-the-shelf components. The three-quarter-wavelength structure is operated at its second harmonic with the purpose of measuring higher electron densities. New theory developments for interpreting the probe measurements include the use of a transmission line model to find an accurate relationship between the resonant frequency of the probe and the electron density, including effects of partially covering the probes with epoxy. Measurements are taken in an inductively coupled plasma sustained in argon at pressures below 50 mTorr. Results are compared with Langmuir probe and interferometry measurements.

Controlled methyl-esterification of pectin catalyzed by cation exchange resin.

This study developed a new method to methyl-esterify pectin using a cation exchange resin. Homogalacturonan (HG)-type pectin (WGPA-3-HG) and rhamnogalacturonan (RG)-I-type pectin (AHP-RG) obtained from the roots of Panax ginseng and sunflower heads, respectively, were used as models. Compared to commonly used methyl-esterification methods that use either methyl iodide or acidified methanol, the developed method can methyl-esterify both HG- and RG-I-type pectins without degrading their structures via ß-elimination or acid hydrolysis. In addition, by modifying reaction conditions, including the mass ratio of resin to pectin, reaction time, and temperature, the degree of esterification can be controlled. Moreover, the resin and methanol can be recycled to conserve resources, lower costs, and reduce environmental pollution. This new methodology will be highly useful for industrial esterification of pectin.