Dendrobium Multi-Omics Reveal Lipid Remodeling in Response to Freezing.

Freezing damage is a common phenomenon responsible for reduced yields of economic crops. Regulation of lipid metabolism plays an important role in plant growth and adaptation during freezing. We previously carried out transcriptome and untargeted metabolome analyses to determine the regulation of flavonol and anthocyanin biosynthesis during freezing treatment (FT) and post-freezing recovery (FR) in Dendrobium catenatum. However, changes in lipid levels are hard to confirm by untargeted metabolomics analysis alone. Regulation of lipid metabolism in response to freezing is largely unknown in Dendrobium. In this study, a multi-omics strategy was used to offer a better means of studying metabolic flow during FT and FR. To this end, 6976 proteins were identified by the 4D_label-free proteome, including 5343 quantified proteins. For each of the two conditions, we enriched differentially accumulated proteins (DAPs) into 15 gene ontology (GO) terms, including primary metabolism, lipid metabolism, and photosynthesis processes. We also identified 7 lipid categories and 3672 lipid species using lipidome assays. We found significant remodeling occurring in the phospholipid category during FT and FR. We also found that most sphingolipids were significantly upregulated. An integrated multi-omics analysis revealed significant changes in the expression levels of 141 mRNAs and encoding proteins under both FT and FR conditions. During FT, phospholipase A (PLA) and phospholipase D (PLD) were associated with phospholipid editing and galactolipid remodeling. These results provide valuable new insights into how the freezing tolerance of D. catenatum might be improved by genetic engineering.

Identification of Two GDSL-Type Esterase/Lipase Genes Related to Tissue-Specific Lipolysis in Dendrobium catenatum by Multi-Omics Analysis.

Dendrobium catenatum is an important herb and widely cultivated in China. GDSL-Type Esterase/Lipase proteins (GELPs) are widely distributed in plants and play crucial roles in stress responses, plant growth, and development. However, no identification or functional analysis of GELPs was reported in D. catenatum. This study identifies 52 GELPs in D. catenatum genome, which is classified into four groups by phylogenetic analysis. Four conservative blocks (Ser-Gly-Asn-His) are found in most GELP domains. Transcriptome analysis reveals the expression profiles of GELPs in different organs and flowering phases. Co-expression analysis of the transcriptome and lipidome identifies a GELP gene, Dca016600, that positively correlates with 23 lipids. The purified Dca016600 protein shows the optimum pH is active from 8.0 to 8.5, and the optimum temperature is active from 30 °C to 40 °C. The kinetic study provides Vmax (233.43 µmol·min-1·mg-1) and Km (1.49 mM) for substrate p-nitrophenyl palmitate (p-NPP). Integrated analysis of the transcriptome and proteome identifies a GELP gene, Dca005399, which is specially induced by freezing. Interestingly, Dca005399 shows high expression in symbiotic germination seeds and sepals. This study provides new insights into the function of D. catenatum GELPs in plant development and stress tolerance.

Metabolic Profiling of Terpene Diversity and the Response of Prenylsynthase-Terpene Synthase Genes during Biotic and Abiotic Stresses in Dendrobium catenatum.

Dendrobium catenatum is a widely cultivated Chinese orchid herb rich in abundant secondary metabolites, such as terpenes. However, terpene distribution and characterization of terpene biosynthesis-related genes remain unknown in D. catenatum. In this study, metabolic profiling was performed to analyze terpene distribution in the root, stem, leaf, and flower of D. catenatum. A total of 74 terpene compounds were identified and classified. Clustering analysis revealed that terpene compounds exhibited a tissue-specific accumulation, including monoterpenes in the flowers, sesquiterpenes in the stems, and triterpenes in the roots. Transcriptome analysis revealed that the 'terpenoid backbone biosynthesis' pathway was only significantly enriched in root vs. flower. The expression of terpene biosynthesis-related genes was spatiotemporal in the flowers. Prenylsynthase-terpene synthases (PS-TPSs) are the largest and core enzymes for generating terpene diversity. By systematic sequence analysis of six species, 318 PS-TPSs were classified into 10 groups and 51 DcaPS-TPSs were found in eight of them. Eighteen DcaPS-TPSs were regulated by circadian rhythm under drought stress. Most of the DcaPS-TPSs were influenced by cold stress and fungi infection. The cis-element of the majority of the DcaPS-TPS promoters was related to abiotic stress and plant development. Methyl jasmonate levels were significantly associated with DcaTPSs expression and terpene biosynthesis. These results provide insight into further functional investigation of DcaPS-TPSs and the regulation of terpene biosynthesis in Dendrobium.

Overexpression of arogenate dehydratase reveals an upstream point of metabolic control in phenylalanine biosynthesis.

Out of the three aromatic amino acids, the highest flux in plants is directed towards phenylalanine, which is utilized to synthesize proteins and thousands of phenolic metabolites contributing to plant fitness. Phenylalanine is produced predominantly in plastids via the shikimate pathway and subsequent arogenate pathway, both of which are subject to complex transcriptional and post-transcriptional regulation. Previously, it was shown that allosteric feedback inhibition of arogenate dehydratase (ADT), which catalyzes the final step of the arogenate pathway, restricts flux through phenylalanine biosynthesis. Here, we show that in petunia (Petunia hybrida) flowers, which typically produce high phenylalanine levels, ADT regulation is relaxed, but not eliminated. Moderate expression of a feedback-insensitive ADT increased flux towards phenylalanine, while high overexpression paradoxically reduced phenylalanine formation. This reduction could be partially, but not fully, recovered by bypassing other known metabolic flux control points in the aromatic amino acid network. Using comparative transcriptomics, reverse genetics, and metabolic flux analysis, we discovered that transcriptional regulation of the d-ribulose-5-phosphate 3-epimerase gene in the pentose phosphate pathway controls flux into the shikimate pathway. Taken together, our findings reveal that regulation within and upstream of the shikimate pathway shares control over phenylalanine biosynthesis in the plant cell.

Identification and Expression Profiling of Nonphosphorus Glycerolipid Synthase Genes in Response to Abiotic Stresses in Dendrobium catenatum.

Dendrobium catenatum, a valuable Chinese herb, frequently experiences abiotic stresses, such as cold and drought, under natural conditions. Nonphosphorus glycerolipid synthase (NGLS) genes are closely linked to the homeostasis of membrane lipids under abiotic stress in plants. However, there is limited information on NGLS genes in D. catenatum. In this study, a total of eight DcaNGLS genes were identified from the D. catenatum genome; these included three monogalactosyldiacylglycerol synthase (DcaMGD1, 2, 3) genes, two digalactosyldiacylglycerol synthase (DcaDGD1, 2) genes, and three sulfoquinovosyldiacylglycerol synthase (DcaSQD1, 2.1, 2.2) genes. The gene structures and conserved motifs in the DcaNGLSs showed a high conservation during their evolution. Gene expression profiling showed that the DcaNGLSs were highly expressed in specific tissues and during rapid growth stages. Furthermore, most DcaNGLSs were strongly induced by freezing and post-freezing recovery. DcaMGD1 and DcaSQDs were greatly induced by salt stress in leaves, while DcaDGDs were primarily induced by salt stress in roots. Under drought stress, most DcaNGLSs were regulated by circadian rhythms, and DcaSQD2 was closely associated with drought recovery. Transcriptome analysis also revealed that MYB might be regulated by circadian rhythm and co-expressed with DcaNGLSs under drought stress. These results provide insight for the further functional investigation of NGLS and the regulation of nonphosphorus glycerolipid biosynthesis in Dendrobium.

Long Non-coding RNA RUNDC3A-AS1 Promotes Lung Metastasis of Thyroid Cancer via Targeting the miR-182-5p/ADAM9.

Long non-coding RNAs (lncRNAs) have been identified as influential indicators in variety of malignancies. Among which, LncRNA RUNDC3A-AS1 is reported to upregulate in thyroid cancer. However, the expression pattern and the pathological function of lncRNA RUNDC3A-AS1 in thyroid cancer is unclear. In this study, we examined the expression levels of lncRNA RUNDC3A-AS1 in the thyroid cancer tissues and cell lines via RT-qPCR analysis. The effects of RUNDC3A-AS1 on thyroid cancer cell metastasis were detected by transwell chamber assay, scratch assay in vitro and lung metastasis model in vivo. The results indicated that RUNDC3A-AS1 was highly expressed in the thyroid cancer tissues and cell lines. Functionally, knockdown of RUNDC3A-AS1 could repress the migration and invasion of thyroid cancer cells in vitro, and inhibit thyroid cancer metastasis to lung in vivo. Mechanistically, RUNDC3A-AS1 served as an inhibitor of miR-182-5p in tumor tissues and cell lines. RUNDC3A-AS1 inhibited the expression of miR-182-5p to increase the expression level of ADAM9, thus further aggravating the malignancy of thyroid cancer. Therefore, the RUNDC3A-AS1/miR-182-5p/ADAM9 axis may be a potential therapeutic target for the treatment of thyroid cancer metastasis.

Prognostic factors in patients with persistent/recurrent differentiated thyroid carcinoma after comprehensive treatment

Objective: To investigate the prognostic factors of patients with persistent/recurrent differentiated thyroid carcinoma (DTC) especially with external invasive persistent recurrent DTC after comprehensive treatment. Methods: The clinical data of 525 patients with persistent/recurrent DTC who underwent surgical treatment from August 2011 to June 2021 in the Department of Head and Neck Surgery of Jiangsu Cancer Hospital were retrospectively analyzed. The prognostic factors affecting overall survival (OS) and relapse-free survival (RFS) of persistent/recurrent DTC, especially external invasive persistent/recurrent DTC were analyzed. Results: Among 525 patients, 318 patients underwent thyroidectomy, 359 patients underwent central lymph node dissection, and 409 patients underwent lateral cervical lymph node dissection. Among 493 followed-up patients, 5-year OS and RFS were 95.10% and 89.60%, 8-year OS and RFS were 91.80% and 81.30%. Cox regression analysis showed that in patients with persistent/recurrent DTC after comprehensive treatment, age ≥55 years at reoperation after recurrence, male gender and distant metastasis were independent risk factors of OS (all P<0.05); while the simultaneous invasion of thyroid and lymph nodes, multiple organ invasion and the number of previous operations ≥2 were independent risk factors of RFS (all P<0.05). In patients with external invasive persistent/recurrent DTC after comprehensive treatment, age ≥55 years at reoperation after recurrence and male gender were independent risk factors of OS (both P<0.05); while multiple organ invasion and the number of previous operations ≥2 were independent risk factors of RFS (both P<0.05). Conclusions: Male patients aged 55 years old and above, with distant metastasis have a higher risk of poorer prognosis in persistent/recurrent DTC; while patients with simultaneous external invasion of thyroid and lymph nodes, multiple organ invasion and the number of previous operations ≥2 are more likely to relapse. For external invasive persistent/recurrent DTC, male patients aged 55 years old and above have a higher risk of poorer prognosis; while patients with multiple organ invasion and the number of previous operations ≥2 are more likely to have recurrence.

Prognostic factors and the effect of radioiodine on patients with locally advanced differentiated thyroid cancer.

BACKGROUND: Locally advanced differentiated thyroid cancer (DTC) is rare. The optimal treatment remains controversial. This study was to investigate the natural history and prognostic factors of patients with locally advanced DTC and assess the effects of radioiodine therapy for locally advanced DTC. METHODS: A retrospective study was performed in 259 patients with locally advanced DTC. The clinicopathological features, prognostic factors and the effects of radioiodine therapy were evaluated using univariate and multivariate statistical analysis. RESULTS: Among the clinicopathological characteristics of locally advanced DTC, the patient's age (unfavourable >55 years), extent of primary tumour (more widely extrathyroidal extension showed a worse prognosis than others), tumor size, histopathological classifications and distant metastases were the significant prognostic factors. With regard to the effects of RAI on local invasive DTC, neither T3b nor T4 patients without distant metastases could benefit from performance of 131I therapy for over survival and locoregional relapse-free survival. CONCLUSIONS: In patients with locally advanced DTC, the independent prognostic factors were age, extent of extrathyroidal invasion, tumor size, histopathological classifications and distant metastases. Adjuvant postoperative RAI did not affect overall survival and locoregional control in patients with locally advanced DTC who had no distant metastasis disease. Given the results, we suggested radioiodine would not be applied for metastasis-free patients with locally advanced DTC postoperatively.

Modulation of auxin formation by the cytosolic phenylalanine biosynthetic pathway.

In plants, phenylalanine biosynthesis occurs via two compartmentally separated pathways. Overexpression of petunia chorismate mutase 2 (PhCM2), which catalyzes the committed step of the cytosolic pathway, increased flux in cytosolic phenylalanine biosynthesis, but paradoxically decreased the overall levels of phenylalanine and phenylalanine-derived volatiles. Concomitantly, the levels of auxins, including indole-3-acetic acid and its precursor indole-3-pyruvic acid, were elevated. Biochemical and genetic analyses revealed the existence of metabolic crosstalk between the cytosolic phenylalanine biosynthesis and tryptophan-dependent auxin biosynthesis mediated by an aminotransferase that uses a cytosolic phenylalanine biosynthetic pathway intermediate, phenylpyruvate, as an amino acceptor for auxin formation.

Correction to: Hsa_circ_0058124 promotes papillary thyroid cancer tumorigenesis and invasiveness through the NOTCH3/GATAD2A axis.

In the original publication of this manuscript [1], the Fig. 6a invasion si-hsa_circ_0058124_2# group (row 2 right and row 3 right) and Fig. 9c TPC-1 clone formation assay control group (row 1 left) were misplaced and need to be revised. The updated figures are shown below.

Hsa_circ_0058124 promotes papillary thyroid cancer tumorigenesis and invasiveness through the NOTCH3/GATAD2A axis.

BACKGROUND: Despite a good and overall prognosis, papillary thyroid cancer (PTC) can still affect the quality of life of many patients, and can even be life-threatening due to its invasiveness and metastasis. Emerging studies demonstrate that circular RNAs (circRNAs) participate in the regulation of various cancers. However, the circRNA profile in invasive PTC is still not well understood. METHODS: Competing endogenous RNA (ceRNA) microarrays were performed to determine circRNAs contributed to the tumorigenesis and invasiveness of PTC. Bioinformatics methods were used to narrow down the candidate circRNAs. Quantitative real-time polymerase chain reaction (qRT-PCR) assays revealed a significant upregulation of hsa_circ_0058124 in PTC tissue and a close correlation with a poor prognosis for PTC patients. RNA fluorescence in situ hybridization and Cell fractionation assay were used to investigate the subcellular location of hsa_circ_0058124. Then, we examined the functions of hsa_circ_0058124 in PTC by cell proliferation, cell cycle, apoptosis, migration and invasion assay. Mechanistically, RNA sequencing and GSEA analysis were applied to predict the downstream pathway of hsa_circ_0058124. Dual-luciferase report assays were used to explore the potential miRNA sponge role of hsa_circ_0058124. Western blotting, cell proliferation, cell cycle, cell apoptosis, migration and invasion, and mouse xenograft assay were used to validate the effects of hsa_circ_0058124/NOTCH3/GATAD2A axis on PTC progression. RESULTS: In the current study, a novel hsa_circ_0058124 on 2q35 was identified and explored in PTC. Hsa_circ_0058124 is associated with the malignant features and poor outcomes of PTC patients. Hsa_circ_0058124 acts as an oncogenic driver that promotes PTC cell proliferation, tumorigenicity, tumor invasion, and metastasis, which functions as a competing endogenous RNA to modulate miRNA-218-5p and its target gene NUMB expression, and consequently with repression of the NOTCH3/GATAD2A signaling axis in vitro and in vivo. CONCLUSIONS: This study unveils a novel biomarker panel consisting of the hsa_circ_0058124/NOTCH3/GATAD2A axis which is critical for PTC tumorigenesis and invasiveness and may represent a novel therapeutic target for intervening in PTC progression.

Over-expression of miR-206 decreases the Euthyrox-resistance by targeting MAP4K3 in papillary thyroid carcinoma.

PURPOSE: microRNAs (miRNAs) play a critical role in drug resistance of multiple cancers including papillary thyroid carcinoma (PTC), indicating the potential of miRNAs as chemoresistance regulators in cancer treatment. The aim of this paper is to explore the relationship between miR-206 and chemoresistance of PTC. METHODS: qRT-PCR was conducted to examine the expression of miR-206 in PTC tissues, parental and TPC-1/euthyrox. The CCK-8 assay, EdU assay and flow cytometry were performed to test cells viability, proliferation and apoptosis, respectively. Luciferase reporter assay was used to confirm the potential target of miR-206. Western blotting analysis was performed to evaluate the expressions of related-proteins. RESULTS: miR-206 was significantly down-regulated in PTC tissues, parental and TPC-1/euthyrox. Moreover, the expression of miR-206 was exceptionally lower in TPC-1/euthyrox cells than that in TPC-1 cells. Furthermore, we found that over-expression of miR-206 could notably decrease the IC50 values both in TPC-1 and TPC-1/euthyrox cells, which indicated that miR-206 played an essential role in the euthyrox resistance in PTC. In addition, up-regulation of miR-206 inhibited the proliferation, induced apoptosis, suppressed the expressions of multidrug resistance-related proteins, including p-gp, MRP, BCRP and LRP, in euthyrox-resistant PTC cells. Besides, over-expression of miR-206 could notably promoted the expression of NIS, an intrinsic membrane protein that mediates the active transport of iodide into the thyroid and other tissues, playing a critical role in the progress. Further, miR-206 was demonstrated to be able to bind to MAP4K3 and negatively regulated the expression of MAP4K3. Besides, MAP4K3 was clearly up-regulated in PTC tissues, parental and TPC-1/euthyrox cells, and down-regulation of miR-206 attenuated the effect of si-MAP4K3 on the euthyrox sensitivity in euthyrox-resistant PTC cells. Moreover, TPC-1/euthyrox cells transfected with miR-206 mimics could significantly inhibit the expressions of p-p38, p-JNK and p-Erk, which indicated that miR-206 might play an essential role in the euthyrox resistance in PTC by negatively regulating the p38 and JNK signaling pathway. CONCLUSION: miR-206 contributed to euthyrox resistance in PTC cells through blockage p38 and JNK signaling pathway by targeting MAP4K3, providing a potential therapeutic application for the treatment of patients with euthyrox-resistant PTC in the further.

Completion of the cytosolic post-chorismate phenylalanine biosynthetic pathway in plants.

In addition to being a vital component of proteins, phenylalanine is also a precursor of numerous aromatic primary and secondary metabolites with broad physiological functions. In plants phenylalanine is synthesized predominantly via the arogenate pathway in plastids. Here, we describe the structure, molecular players and subcellular localization of a microbial-like phenylpyruvate pathway for phenylalanine biosynthesis in plants. Using a reverse genetic approach and metabolic flux analysis, we provide evidence that the cytosolic chorismate mutase is responsible for directing carbon flux towards cytosolic phenylalanine production via the phenylpyruvate pathway. We also show that an alternative transcription start site of a known plastidial enzyme produces a functional cytosolic prephenate dehydratase that catalyzes the conversion of prephenate to phenylpyruvate, the intermediate step between chorismate mutase and phenylpyruvate aminotransferase. Thus, our results complete elucidation of phenylalanine biosynthesis via phenylpyruvate in plants, showing that this pathway splits from the known plastidial arogenate pathway at chorismate, instead of prephenate as previously thought, and the complete pathway is localized in the cytosol.

miR-214 regulates papillary thyroid carcinoma cell proliferation and metastasis by targeting PSMD10.

MicroRNAs (miRNAs) have important effects on cancer occurrence and development by adjusting gene expression. The aim of the present study was to examine the role of miR­214 in papillary thyroid carcinoma cell proliferation and metastasis, and its molecular mechanisms. miR­214 was demonstrated to be markedly downregulated in papillary thyroid carcinoma tissues and cells compared with normal, and this was significantly associated with lymph node metastasis, tumor size and TNM stage. Upregulation of miR­214 significantly decreased cell proliferation, and promoted cell apoptosis and cell cycle arrest in papillary thyroid carcinoma cell lines in vitro. By contrast, downregulation of miR­214 resulted in the opposite effects. In addition, miR­214 mimics significantly decreased papillary thyroid carcinoma cell migration and invasion, which was correlated with decreased expression levels of matrix metallopeptidase (MMP)­2 and MMP­9. Restoration of miR­214 expression in papillary thyroid carcinoma cells decreased the activities associated with epithelial­mesenchymal transition (EMT). Furthermore, proteasome 26S subunit non­ATPase 10 (PSMD10) was predicted to be a target of miR­214. Experimental results demonstrated that miR­214 negatively regulated PSMD10 expression by targeting its 3' untranslated region directly. Knockdown of PSMD10 reduced papillary thyroid carcinoma cell clone formation, migration and invasion, most likely by repressing glycogen synthase kinase (GSK)­3ß/ß­catenin and AKT signaling. Finally, a negative correlation was observed between the expression levels of miR­214 and PSMD10 in papillary thyroid carcinoma tissues. Taken together, these data suggested that miR­214 might be a candidate target for the treatment of papillary thyroid carcinoma.

Circulating Long Noncoding RNAs as Biomarkers for Predicting Head and Neck Squamous Cell Carcinoma.

BACKGROUND/AIMS: The anatomical complexity of the head and neck region and the lack of sufficiently specific and sensitive biomarkers often lead to the diagnosis of head and neck squamous cell carcinoma (HNSCC) at advanced stages. To identify novel biomarkers for early diagnosis of primary HNSCC through a minimally invasive method, we investigated circulating long noncoding RNA (lncRNA) levels in plasma of HNSCC patients. METHODS: The global lncRNA expression profiles of HNSCC patients were measured using microarray and next-generation RNA-sequencing (RNA-seq) data from both circulating and tissue samples. The diagnosis prediction model based on the lncRNA signatures and clinical features was evaluated by multi-stage validation and risk score analysis. RESULTS: The data showed that 432 lncRNA transcripts were differentially expressed by fold changes of > 4 in circulating samples and 333 in tissues samples, respectively. Only 12 lncRNAs consistently emerged in these two kinds of samples. After the risk score analysis including a multistage validation, we identified three lncRNAs, namely, HOXA11-AS, LINC00964 and MALAT1, which were up-regulated in the plasma of HNSCC patients compared with those in healthy controls with merged areas under the curve (AUCs) in training and validation sets of 0.925 and 0.839, respectively. CONCLUSION: HOXA11-AS, LINC00964 and MALAT1 might be potential circulating biomarkers for the early detection of HNSCC in the future.

MiR-206 inhibits Head and neck squamous cell carcinoma cell progression by targeting HDAC6 via PTEN/AKT/mTOR pathway.

As a kind of endogenous noncoding small RNA, microRNA (miRNA) plays important roles of regulation to various physiological functions, while its affections on senescence of human Head and neck squamous cell carcinoma (HNSCC) are still unknown. The objective of this study was to investigate the effect of miR-206 in HNSCC tissues, adjacent normal tissues and cell lines, and explore its biological functions in HNSCC. In our study, the level of miR-206 in HNSCC tissues and adjacent normal tissues was detected via real-time qPCR. The effect of miR-206 on cell proliferation was tested by MTT assay, colony formation and cell cycle assays. In order to explore the effect of miR-206 on HNSCC cell migration and invasion, we performed wound healing assays and transwell assays. Luciferase reporter assays were designed to identify the interaction between 3'UTR of HDAC6 and miR-206. The level of signaling pathway-related proteins was determined by western blot. The expression of miR-206 was found to be observably decreased in HNSCC tissues and cell lines through real time-PCR. Restoration of miR-206 weaked cell proliferation, invasion and migration in HNSCC cells and the cell cycle was arrest in S phase. Further explores have shown that miR-206 could inhibit HNSCC cells proliferation by targeting the HDAC6 via PTEN/AKT/mTOR pathway. Taken together, our results demonstrated that miR-206 plays a critical role in HNSCC progression by targeting HDAC6 via PTEN/AKT/mTOR pathway, which might be a potential target for diagnostic and therapeutic in HNSCC.

Identification of a plastidial phenylalanine exporter that influences flux distribution through the phenylalanine biosynthetic network.

In addition to proteins, L-phenylalanine is a versatile precursor for thousands of plant metabolites. Production of phenylalanine-derived compounds is a complex multi-compartmental process using phenylalanine synthesized predominantly in plastids as precursor. The transporter(s) exporting phenylalanine from plastids, however, remains unknown. Here, a gene encoding a Petunia hybrida plastidial cationic amino-acid transporter (PhpCAT) functioning in plastidial phenylalanine export is identified based on homology to an Escherichia coli phenylalanine transporter and co-expression with phenylalanine metabolic genes. Radiolabel transport assays show that PhpCAT exports all three aromatic amino acids. PhpCAT downregulation and overexpression result in decreased and increased levels, respectively, of phenylalanine-derived volatiles, as well as phenylalanine, tyrosine and their biosynthetic intermediates. Metabolic flux analysis reveals that flux through the plastidial phenylalanine biosynthetic pathway is reduced in PhpCAT RNAi lines, suggesting that the rate of phenylalanine export from plastids contributes to regulating flux through the aromatic amino-acid network.

Enhanced cytotoxic activity of cetuximab in EGFR-positive lung cancer by conjugating with gold nanoparticles.

Cetuximab (C225) is a unique agent, targeting epidermal growth factor receptor (EGFR)-positive cancer. However, the therapeutic effect of C225 in EGFR high-expressing non-small cell lung cancer (NSCLC) remains poor. Here, we report that conjugation of C225 with gold nanoparticles (AuNPs) enhances the cytotoxicity of C225 in NSCLC both in vitro and in vivo. The NSCLC cell lines A549 (EGFR(high)) and H1299 (EGFR(low)) were employed to investigate different responses to C225, IgG-AuNPs and C225-AuNPs. The antitumor properties of C225-AuNPs were explored in vivo by establishing a tumor xenograft model in nude mice. Overall, the therapeutic effect of C225-AuNPs was more pronounced in EGFR(high) A549 cells compared with EGFR(low) H1299 cells. The cytotoxic effect of C225-AuNPs in A549 cells increased in a dose-dependent manner. C225-AuNPs significantly suppressed A549 cell proliferation and migration capacity and accelerated apoptosis compared with C225, and this effect was probably due to enhanced EGFR endocytosis and the subsequent suppression of downstream signaling pathway. Finally in the tumor xenograft of nude mice, treatment with C225-AuNPs also led to a significant reduction in tumor weight and volume with low toxicity. Our findings suggest that C225-AuNPs conjugate has promising potential for targeted therapy of EGFR positive NSCLC patients.

Association between MCP-1 -2518A/G polymorphism and cancer risk: evidence from 19 case-control studies.

BACKGROUND: Single nucleotide polymorphisms (SNPs) may affect the development of diseases. The -2518A/G polymorphism in the regulatory region of the monocyte chemo-attractant protein-1 (MCP-1) gene has been reported to be associated with cancer risk. However, the results of previous studies were inconsistent. Therefore, we performed a meta-analysis to obtain a more precise estimation of the relationship between the -2518A/G polymorphism and cancer risk. METHODOLOGY/PRINCIPAL FINDINGS: We performed a meta-analysis, including 4,162 cases and 5,173 controls, to evaluate the strength of the association between the -2518A/G polymorphism and cancer risk. Odds ratio (OR) and 95% confidence intervals (95% CIs) were used to assess the strength of association. Overall, the results indicated that the -2518A/G polymorphism was not statistically associated with cancer risk. However, sub-group analysis revealed that individuals with GG genotypes showed an increased risk of cancer in digestive system compared with carriers of the A allele (GG vs. AA: OR = 1.43, 95%CI = 1.05-1.96, P(heterogeneity) = 0.08; GG vs. AG/AA: OR = 1.29, 95%CI = 1.02-1.64, P(heterogeneity) = 0.14). In addition, the increased risk of GG genotype was also observed in Caucasians (GG vs. AG/AA: OR = 1.81, 95%CI = 1.10-2.96, P(heterogeneity) = 0.02). CONCLUSION: This meta-analysis suggests that the MCP-1 -2518A/G polymorphism may have some relation to digestive system cancer susceptibility or cancer development in Caucasian. Large-scale and well-designed case-control studies are needed to validate the findings.

An alternative pathway contributes to phenylalanine biosynthesis in plants via a cytosolic tyrosine:phenylpyruvate aminotransferase.

Phenylalanine is a vital component of proteins in all living organisms, and in plants is a precursor for thousands of additional metabolites. Animals are incapable of synthesizing phenylalanine and must primarily obtain it directly or indirectly from plants. Although plants can synthesize phenylalanine in plastids through arogenate, the contribution of an alternative pathway via phenylpyruvate, as occurs in most microbes, has not been demonstrated. Here we show that plants also utilize a microbial-like phenylpyruvate pathway to produce phenylalanine, and flux through this route is increased when the entry point to the arogenate pathway is limiting. Unexpectedly, we find the plant phenylpyruvate pathway utilizes a cytosolic aminotransferase that links the coordinated catabolism of tyrosine to serve as the amino donor, thus interconnecting the extra-plastidial metabolism of these amino acids. This discovery uncovers another level of complexity in the plant aromatic amino acid regulatory network, unveiling new targets for metabolic engineering.