Downregulation of phosphoglycerate dehydrogenase inhibits proliferation and enhances cisplatin sensitivity in cervical adenocarcinoma cells by regulating Bcl-2 and caspase-3

Integrative metabolome and transcriptome analyses provide insights into PHGDH in colon cancer organoids

As a rate-limiting enzyme in the endogenous serine de novo synthesis pathway, 3-Phosphoglycerate dehydrogenase (PHGDH) has been widely concerned about its role in a variety of tumors including colon cancer and the development of inhibitors. In our previous study, we studied PHGDH in colon cancer cell lines. However, with the development of personalized therapy, we realized that in scientific research, two-dimensional cell lines lost a lot of original characteristic information during long-term culture, and the results obtained may not be enough to support the conclusion. Patient-derived tumor organoids maintain genomic stability and make up for information missing from cell lines due to monoclonal growth. Therefore, in our study, a colon cancer organoid with high PHGDH expression was selected and analyzed for transcriptomic and metabolomic changes through targeted inhibition of PHGDH. The results showed that inhibition of PHGDH significantly inhibited the proliferation of colon cancer organoids. The transcriptome, metabolome, and combined omics analysis showed that the changes in colon cancer organoids after inhibition of PHGDH were mainly involved in PRSS1 and PRSS56, steroid hormone biosynthesis, phenylalanine metabolism, ascorbate and aldarate metabolism, and tyrosine metabolism. In our study, the role of PHGDH in serine metabolism in colon cancer organoids was clarified by multi-omics analysis to provide new knowledge for an in-depth understanding of serine metabolism and PHGDH function in colon cancer.

PHGDH: a novel therapeutic target in cancer

Serine is a key contributor to the generation of one-carbon units for DNA synthesis during cellular proliferation. In addition, it plays a crucial role in the production of antioxidants that prevent abnormal proliferation and stress in cancer cells. In recent studies, the relationship between cancer metabolism and the serine biosynthesis pathway has been highlighted. In this context, 3-phosphoglycerate dehydrogenase (PHGDH) is notable as a key enzyme that functions as the primary rate-limiting enzyme in the serine biosynthesis pathway, facilitating the conversion of 3-phosphoglycerate to 3-phosphohydroxypyruvate. Elevated PHGDH activity in diverse cancer cells is mediated through genetic amplification, posttranslational modification, increased transcription, and allosteric regulation. Ultimately, these characteristics allow PHGDH to not only influence the growth and progression of cancer but also play an important role in metastasis and drug resistance. Consequently, PHGDH has emerged as a crucial focal point in cancer research. In this review, the structural aspects of PHGDH and its involvement in one-carbon metabolism are investigated, and PHGDH is proposed as a potential therapeutic target in diverse cancers. By elucidating how PHGDH expression promotes cancer growth, the goal of this review is to provide insight into innovative treatment strategies. This paper aims to reveal how PHGDH inhibitors can overcome resistance mechanisms, contributing to the development of effective cancer treatments.

Identification of benzo[b]thiophene-1,1-dioxide derivatives as novel PHGDH covalent inhibitors

The increased de novo serine biosynthesis confers many advantages for tumorigenesis and metastasis. Phosphoglycerate dehydrogenase (PHGDH), a rate-limiting enzyme in serine biogenesis, exhibits hyperactivity across multiple tumors and emerges as a promising target for cancer treatment. Through screening our in-house compound library, we identified compound Stattic as a potent PHGDH inhibitor (IC50 = 1.98 ± 0.66 µM). Subsequent exploration in structural activity relationships led to the discovery of compound B12 that demonstrated the increased enzymatic inhibitory activity (IC50 = 0.29 ± 0.02 μM). Furthermore, B12 exhibited robust inhibitory effects on the proliferation of MDA-MB-468, NCI-H1975, HT1080 and PC9 cells that overexpress PHGDH. Additionally, using a [U-13C6]-glucose tracing assay, B12 was found to reduce the production of glucose-derived serine in MDA-MB-468 cells. Finally, mass spectrometry-based peptide profiling, mutagenesis experiment and molecular docking study collectively suggested that B12 formed a covalent bond with Cys421 of PHGDH.

Effect of aza-BODIPY-photodynamic therapy on the expression of carcinoma-associated genes and cell death mode

BACKGROUND

Breast cancer is the most common cancer affecting women worldwide.Photodynamic therapy(PDT) has now proven to be a promising form of cancer therapy due to its targeted and low cytotoxicity to healthy cells and tissues.PDT is a technique used to create cell death localized by light after application of a light-sensitive agent.Aza-BODIPY is a promising photosensitizer for use in PDT. Our results showed that aza-BODIPY-PDT induced apoptosis, probably through p53 and caspase3 in MCF-7 cells. Future studies should delineate the molecular mechanisms underlying aza-BODIPY-PDT-induced cell death for a better understanding of the signaling pathways modulated by the therapy so that this novel technology could be implemented in the clinic for treating breast cancer.

AIM

In this study,we aimed to determine the change in the expression levels of 88 carcinoma-associated genes induced by aza-BODIPY-PDT were analyzed so as to understand the specific pathways that are modulated by aza-BODIPY-PDT.

MATERIAL METHOD

In this study,the molecular basis of the anti-cancer activity of aza-BODIPY-PDT was investigated.Induction of apoptosis and necrosis in MCF-7 breast cancer cells after treatment with aza- BODIPY derivative with phthalonitrile substituents (aza-BODIPY) followed by light exposure was evaluated by Annexin V 7- Aminoactinomycin D (7-AAD) flow cytometry.

RESULTS

Aza-BODIPY-PDT induced cell death in MCF-7 cells treated with aza-BODIPY-PDT; flow cytometry revealed that 28 % of the cells died by apoptosis. Seven of the 88 carcinoma-associated genes that were assayed were differentially expressed -EGF, LEF1, WNT1, TCF7, and TGFBR2 were downregulated, and CASP3 and TP53 were upregulated - in cells subjected to aza-BODIPY-PDT.This made us think that the aza-BODIPY-PDT induced caspase 3 and p53-mediated apoptosis in MCF7 cells.

CONCLUSION

In our study,it was determined that the application of aza-BODIPY-PDT to MCF7 cells had a negative effect on cell connectivity and cell cycle.The fact that the same effect was not observed in control cells and MCF7 cells in the dark field of aza-BODIPY indicates that aza-BODIPY has a strong phodynamic anticancer effect.

The Role of ESRP1 in the Regulation of PHGDH in Estrogen Receptor-Positive Breast Cancer

Resistance to hormone therapy leads to a recurrence of estrogen receptor-positive breast cancer. We have demonstrated that the epithelial splicing regulatory protein 1 (ESRP1) significantly affects cell/tumor growth and metabolism and is associated with a poor prognosis in this breast cancer subtype. In this study, we aimed to investigate the ESRP1 protein-messenger RNA (mRNA) interaction in hormone therapy-resistant breast cancer. RNA-binding protein immunoprecipitation (RIP) followed by Clariom D (Applied Biosystems/Thermo Fisher Scientific) transcriptomics microarray (RIP-Chip) was performed to identify mRNA-binding partners of ESRP1. The integration of RIP-Chip and immunoprecipitation-mass spectrometry analyses identified phosphoglycerate dehydrogenase (PHGDH), a key metabolic enzyme, as a binding partner of ESRP1 in hormone-resistant breast cancer. Bioinformatic analysis showed ESRP1 binding to the 5' untranslated region of PHGDH. RNA electrophoresis mobility shift assay and RIP-quantitative reverse transcription-polymerase chain reaction further validated the ESRP1-PHGDH binding. In addition, knockdown of ESRP1 decreased PHGDH mRNA stability significantly, suggesting the posttranscriptional regulation of PHGDH by ESRP1. The presence or absence of ESRP1 levels significantly affected the stability in tamoxifen-resistant LCC2 and fulvestrant-resistant LCC9 cells. PHGDH knockdown in tamoxifen-resistant cells further reduced the oxygen consumption rate (ranging from P = .005 and P = .02), mimicking the effects of ESRP1 knockdown. Glycolytic parameters were also altered (ranging P = .001 and P = .005). ESRP1 levels did not affect the stability of PHGDH in T-47D cells, although knockdown of PHGDH affected the growth of these cells. In conclusion, to our knowledge, this study, for the first time, reports that ESRP1 binds to the 5' untranslated region of PHGDH, increasing its mRNA stability in hormone therapy-resistant estrogen receptor-positive breast cancer. These findings provide evidence for a novel mechanism of action of RNA-binding proteins such as ESRP1. These new insights could assist in developing novel strategies for the treatment of hormone therapy-resistant breast cancer.

The role of serine metabolism in lung cancer: From oncogenesis to tumor treatment

Metabolic reprogramming is an important hallmark of malignant tumors. Serine is a non-essential amino acid involved in cell proliferation. Serine metabolism, especially the de novo serine synthesis pathway, forms a metabolic network with glycolysis, folate cycle, and one-carbon metabolism, which is essential for rapidly proliferating cells. Owing to the rapid development in metabolomics, abnormal serine metabolism may serve as a biomarker for the early diagnosis and pathological typing of tumors. Targeting serine metabolism also plays an essential role in precision and personalized cancer therapy. This article is a systematic review of de novo serine biosynthesis and the link between serine and folate metabolism in tumorigenesis, particularly in lung cancer. In addition, we discuss the potential of serine metabolism to improve tumor treatment.

SHMT2 promotes cell viability and inhibits ROS-dependent, mitochondrial-mediated apoptosis via the intrinsic signaling pathway in bladder cancer cells

Mitochondrial serine hydroxymethyltransferase (SHMT2) catalyzes the conversion of serine to glycine and concomitantly produces one-carbon units to support cell growth and is upregulated in various cancer cells. SHMT2 knockdown triggers cell apoptosis; however, the detailed mechanism of apoptosis induced by SHMT2 inactivation remains unknown. Here, we demonstrate that SHMT2 supports the proliferation of bladder cancer (BC) cells by maintaining redox homeostasis. SHMT2 knockout decreased the pools of purine and one-carbon units and delayed cell cycle progression in a manner that was rescued by formate, demonstrating that SHMT2-mediated one-carbon units are essential for BC cell proliferation. SHMT2 deficiency promoted the accumulation of intracellular reactive oxygen species (ROS) by decreasing the NADH/NAD+, NADPH/NADP+, and GSH/GSSG ratios, leading to a loss in mitochondrial membrane potential, release of cytochrome c, translocation of Bcl-2 family protein and activation of caspase-3. Notably, blocking ROS production with the one-carbon donor formate and the ROS scavenger N-acetyl-cysteine (NAC) effectively rescued SHMT2 deficiency-induced cell apoptosis via the intrinsic signaling pathway. Treatment with the SHMT inhibitor SHIN1 resulted in a significant inhibitory effect on cell proliferation and induced cell apoptosis. Formate and NAC rescued SHIN1-induced cell apoptosis. Our findings reveal an important mechanism by which the loss of SHMT2 triggers ROS-dependent, mitochondrial-mediated apoptosis, which gives insight into the link between serine metabolism and cell apoptosis and provides a promising target for BC treatment and drug discovery.

Effects of insufficient serine on health and selenoprotein expression in rats and their offspring

Objective

To observe the impact of insufficient exogenous and/or endogenous serine on selenoprotein expression and health of pregnant rats and their offspring.

Method

Experiment 1 was conducted in male rats, in which the dose-dependent effects of serine on selenoprotein expression and thyroid hormones (T3, T4 and TSH) were investigated by feeding either a serine adequate diet (20C), serine-deprived diet (20CSD) or 20CSD with different serine levels (0.5, 1.0, and 2.0 times the amount of serine in 20C). In experiment 2, a PHGDH inhibitor was administrated to pregnant rats fed either 20C or 20CSD. Blood and organ tissues of pregnant rats and offspring were subjected to the analyses of thyroid hormone, serine and homocysteine and GPx3 and SELENOP in plasma and expression of GPx1 and DIO1, 2 in tissues respectively.

Result

In experiment 1, plasma SELENOP and GPx3 levels in adult male rats increased with the increasing dose of serine. Immunohistochemical results showed that GPx1 expression in liver and kidney of male rats also increased with increasing serine supplementation. Amongst all diet groups, only male rats fed 20CSD had significantly lower plasma TSH and T4 levels (P < 0.05). In experiment 2, GPx1 and DIO2 expression in the liver and kidney were suppressed in pregnant rats administered with a PHGDH compared to those who were not (P < 0.05). There were no significant differences in plasma T4 and T3 amongst all diet groups (P > 0.05). Also, offspring born to pregnant rats administered with a PHGDH inhibitor exhibited slower growth rates and hyperhomocysteinemia compared to offspring from mothers not administered with the inhibitor (P < 0.05). Conclusions: Insufficient exogenous serine through the diet decreased selenoprotein synthesis in adult male rats. However, this was not observed in pregnant rats, whereby exogenous or endogenous serine deficiency had no effect on the selenoprotein levels. A possible explanation is that dams may have an adaptive mechanism to limit maternal serine utilization and ensure adequate supply to the fetus.

Pharmacological inhibition of serine synthesis enhances temozolomide efficacy by decreasing O6-methylguanine DNA methyltransferase (MGMT) expression and reactive oxygen species (ROS)-mediated DNA damage in glioblastoma

Glioblastoma (GBM) is the most malignant primary tumor in the central nervous system of adults. Temozolomide (TMZ), an alkylating agent, is the first-line chemotherapeutic agent for GBM patients. However, its efficacy is often limited by innate or acquired chemoresistance. Cancer cells can rewire their metabolic programming to support rapid growth and sustain cell survival against chemotherapies. An example is the de novo serine synthesis pathway (SSP), one of the main branches from glycolysis that is highly activated in multiple cancers in promoting cancer progression and inducing chemotherapy resistance. However, the roles of SSP in TMZ therapy for GBM patients remain unexplored. In this study, we employed NCT503, a highly selective inhibitor of phosphoglycerate dehydrogenase (PHGDH, the first rate-limiting enzyme of SSP), to study whether inhibition of SSP may enhance TMZ efficacy in MGMT-positive GBMs. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), flowcytometry and colony formation assays demonstrated that NCT503 worked synergistically with TMZ in suppressing GBM cell growth and inducing apoptosis in T98G and U118 cells in vitro. U118 and patient-derived GBM subcutaneous xenograft models showed that combined NCT503 and TMZ treatment inhibited GBM growth and promoted apoptosis more significantly than would each treatment alone in vivo. Mechanistically, we found that NCT503 treatment decreased MGMT expression possibly by modulating the Wnt/β-catenin pathway. Moreover, intracellular levels of reactive oxygen species were elevated especially when NCT503 and TMZ treatments were combined, and the synergistic effects could be partially negated by NAC, a classic scavenger of reactive oxygen species. Taken together, these results suggest that NCT503 may be a promising agent for augmenting TMZ efficacy in the treatment of GBM, especially in TMZ-resistant GBMs with high expression of MGMT.

Biophysical and biochemical properties of PHGDH revealed by studies on PHGDH inhibitors

The rate-limiting serine biogenesis enzyme PHGDH is overexpressed in cancers. Both serine withdrawal and genetic/pharmacological inhibition of PHGDH have demonstrated promising tumor-suppressing activities. However, the enzyme properties of PHGDH are not well understood and the discovery of PHGDH inhibitors is still in its infancy. Here, oridonin was identified from a natural product library as a new PHGDH inhibitor. The crystal structure of PHGDH in complex with oridonin revealed a new allosteric site. The binding of oridonin to this site reduced the activity of the enzyme by relocating R54, a residue involved in substrate binding. Mutagenesis studies showed that PHGDH activity was very sensitive to cysteine mutations, especially those in the substrate binding domain. Conjugation of oridonin and other reported covalent PHGDH inhibitors to these sites will therefore inhibit PHGDH. In addition to being inhibited enzymatically, PHGDH can also be inhibited by protein aggregation and proteasome-mediated degradation. Several tested PHGDH cancer mutants showed altered enzymatic activity, which can be explained by protein structure and stability. Overall, the above studies present new biophysical and biochemical insights into PHGDH and may facilitate the future design of PHGDH inhibitors.

Expression of Glucose Metabolism-Related Proteins in Adrenal Neoplasms

PURPOSE

The aim of this study was to investigate the expression patterns of glucose metabolism-related proteins and their clinicopathologic implications in adrenal cortical neoplasms (ACN) and pheochromocytoma (PCC).

METHODS

Immunohistochemical staining was performed to evaluate glucose metabolism-related proteins (GLUT1, CAIX, hexokinase II, G6PDH, PHGDH, and SHMT1) in 132 ACN cases (115 adrenal cortical adenoma [ACA] and 17 adrenal cortical carcinoma [ACC]) and 189 PCC cases.

RESULTS

Expression levels of GLUT1 in tumor cells ([T]; p < 0.001), GLUT1 in stromal cells ([S]; p < 0.001), G6PDH (p < 0.001), and SHMT1 (p = 0.002) were higher in ACN than in PCC. GLUT1 (T; p = 0.045) and PHGDH (p = 0.043) levels were higher in ACC than in ACA. In a univariate analysis of ACN, GLUT1 (T; p = 0.017), CAIX (S; p = 0.003), and PHGDH (p = 0.009) levels were correlated with a shorter overall survival (OS). GLUT1 (T; p = 0.001) and PHGDH (p < 0.001) were related to a shorter OS in PCC. GLUT1 (T) positivity (p = 0.043) in ACN predicted a poor OS in a multivariate Cox analysis. In PCC, high GAPP score (p = 0.026), GLUT1 (T; p = 0.002), and PHGDH (p < 0.001) were independent prognostic factors for poor OS.

CONCLUSIONS

The adrenal gland tumors ACN and PCC had different expression patterns of glucose metabolism-related proteins (GLUT1, G6PDH, and SHMT1), with higher expression levels in ACN than in PCC. GLUT1 and PHGDH were significant prognostic factors in these adrenal neoplasms.

Identification of Blood-Based Glycolysis Gene Associated with Alzheimer's Disease by Integrated Bioinformatics Analysis

BACKGROUND

Alzheimer's disease (AD) is one of many common neurodegenerative diseases without ideal treatment, but early detection and intervention can prevent the disease progression.

OBJECTIVE

This study aimed to identify AD-related glycolysis gene for AD diagnosis and further investigation by integrated bioinformatics analysis.

METHODS

122 subjects were recruited from the affiliated hospitals of Ningbo University between 1 October 2015 and 31 December 2016. Their clinical information and methylation levels of 8 glycolysis genes were assessed. Machine learning algorithms were used to establish an AD prediction model. Receiver operating characteristic curve (AUC) and decision curve analysis (DCA) were used to assess the model. An AD risk factor model was developed by SHapley Additive exPlanations (SHAP) to extract features that had important impacts on AD. Finally, gene expression of AD-related glycolysis genes were validated by AlzData.

RESULTS

An AD prediction model was developed using random forest algorithm with the best average ROC_AUC (0.969544). The threshold probability of the model was positive in the range of 0∼0.9875 by DCA. Eight glycolysis genes (GAPDHS, PKLR, PFKFB3, LDHC, DLD, ALDOC, LDHB, HK3) were identified by SHAP. Five of these genes (PFKFB3, DLD, ALDOC, LDHB, LDHC) have significant differences in gene expression between AD and control groups by Alzdata, while three of the genes (HK3, ALDOC, PKLR) are related to the pathogenesis of AD. GAPDHS is involved in the regulatory network of AD risk genes.

CONCLUSION

We identified 8 AD-related glycolysis genes (GAPDHS, PFKFB3, LDHC, HK3, ALDOC, LDHB, PKLR, DLD) as promising candidate biomarkers for early diagnosis of AD by integrated bioinformatics analysis. Machine learning has the advantage in identifying genes.

Discovery of novel inhibitors of human phosphoglycerate dehydrogenase by activity-directed combinatorial chemical synthesis strategy

Serine, the source of the one-carbon units essential for de novo purine and deoxythymidine synthesis plays a crucial role in the growth of cancer cells. Phosphoglycerate dehydrogenase (PHGDH) which catalyzes the first, rate-limiting step in de novo serine biosynthesis has become a promising target for the cancer treatment. Here we identified H-G6 as a potential PHGDH inhibitor from the screening of an in-house small molecule library based on the enzymatic assay. We adopted activity-directed combinatorial chemical synthesis strategy to optimize this hit compound. Compound b36 was found to be the noncompetitive and the most promising one with IC₅₀ values of 5.96 ± 0.61 μM against PHGDH. Compound b36 inhibited the proliferation of human breast cancer and ovarian cancer cells, reduced intracellular serine synthesis, damaged DNA synthesis, and induced cell cycle arrest. Collectively, our results suggest that b36 is a novel PHGDH inhibitor, which could be a promising modulator to reprogram the serine synthesis pathway and might be a potential anticancer lead worth further exploration.

3-Phosphoglycerate dehydrogenase: a potential target for cancer treatment

BACKGROUND

Metabolic changes have been recognized as an important hallmark of cancer cells. Cancer cells can promote their own growth and proliferation through metabolic reprogramming. Particularly, serine metabolism has frequently been reported to be dysregulated in tumor cells. 3-Phosphoglycerate dehydrogenase (PHGDH) catalyzes the first step in the serine biosynthesis pathway and acts as a rate-limiting enzyme involved in metabolic reprogramming. PHGDH upregulation has been observed in many tumor types, and inhibition of PHGDH expression has been reported to inhibit the proliferation of PHGDH-overexpressing tumor cells, indicating that it may be utilized as a target for cancer treatment. Recently identified inhibitors targeting PHGDH have already shown effectiveness. A further in-depth analysis and concomitant development of PHGDH inhibitors will be of great value for the treatment of cancer.

CONCLUSIONS

In this review we describe in detail the role of PHGDH in various cancers and inhibitors that have recently been identified to highlight progression in cancer treatment. We also discuss the development of new drugs and treatment modalities based on PHGDH targets. Overexpression of PHGDH has been observed in melanoma, breast cancer, nasopharyngeal carcinoma, parathyroid adenoma, glioma, cervical cancer and others. PHGDH may serve as a molecular biomarker for the diagnosis, prognosis and treatment of these cancers. The design and development of novel PHGDH inhibitors may have broad implications for cancer treatment. Therapeutic strategies of PHGDH inhibitors in combination with traditional chemotherapeutic drugs may provide new perspectives for precision medicine and effective personalized treatment for cancer patients.

A retrospective overview of PHGDH and its inhibitors for regulating cancer metabolism

Emerging evidence suggests that cancer metabolism is closely associated to the serine biosynthesis pathway (SSP), in which glycolytic intermediate 3-phosphoglycerate is converted to serine through a three-step enzymatic transformation. As the rate-limiting enzyme in the first step of SSP, phosphoglycerate dehydrogenase (PHGDH) is overexpressed in various diseases, especially in cancer. Genetic knockdown or silencing of PHGDH exhibits obvious anti-tumor response both in vitro and in vivo, demonstrating that PHGDH is a promising drug target for cancer therapy. So far, several types of PHGDH inhibitors have been identified as a significant and newly emerging option for anticancer treatment. Herein, this comprehensive review summarizes the recent achievements of PHGDH, especially its critical role in cancer and the development of PHGDH inhibitors in drug discovery.

Extracellular vesicles derived from oesophageal cancer containing P4HB promote muscle wasting via regulating PHGDH/Bcl-2/caspase-3 pathway

Cachexia, characterized by loss of skeletal muscle mass and function, is estimated to inflict the majority of patients with oesophageal squamous cell carcinoma (ESCC) and associated with their poor prognosis. However, its underlying mechanisms remain elusive. Here, we developed an ESCC‐induced cachexia mouse model using human xenograft ESCC cell lines and found that ESCC‐derived extracellular vesicles (EVs) containing prolyl 4‐hydroxylase subunit beta (P4HB) induced apoptosis of skeletal muscle cells. We further identified that P4HB promoted apoptotic response through activating ubiquitin‐dependent proteolytic pathway and regulated the stability of phosphoglycerate dehydrogenase (PHGDH) and subsequent antiapoptotic protein Bcl‐2. Additionally, we proved that the P4HB inhibitor, CCF642, not only rescued apoptosis of muscle cells in vitro, but also prevented body weight loss and muscle wasting in ESCC‐induced cachexia mouse model. Overall, these findings demonstrate a novel pathway for ESCC‐induced muscle wasting and advocate for the development of P4HB as a potential intervention target for cachexia in patients with ESCC.

PHGDH as a mechanism for resistance in metabolically-driven cancers

At the forefront of cancer research is the rapidly evolving understanding of metabolic reprogramming within cancer cells. The expeditious adaptation to metabolic inhibition allows cells to evolve and acquire resistance to targeted treatments, which makes therapeutic exploitation complex but achievable. 3-phosphoglycerate dehydrogenase (PHGDH) is the rate-limiting enzyme of de novo serine biosynthesis and is highly expressed in a variety of cancers, including breast cancer, melanoma, and Ewing’s sarcoma. This review will investigate the role of PHGDH in normal biological processes, leading to the role of PHGDH in the progression of cancer. With an understanding of the molecular mechanisms by which PHGDH expression advances cancer growth, we will highlight the known mechanisms of resistance to cancer therapeutics facilitated by PHGDH biology and identify avenues for combatting PHGDH-driven resistance with inhibitors of PHGDH to allow for the development of effective metabolic therapies.

Characterization of PHGDH expression in bladder cancer: potential targeting therapy with gemcitabine/cisplatin and the contribution of promoter DNA hypomethylation

d‐3‐Phosphoglycerate dehydrogenase (PHGDH) conducts an important step in the synthesis of serine. Importantly, the PHGDH gene is often amplified in certain cancers. Our previous studies revealed that PHGDH gene amplification was associated with poor overall survival in clear cell renal cell carcinoma (ccRCC) and that metabolic reprogramming of serine synthesis through PHGDH recruitment allowed ccRCC cells to survive in unfavorable environments. There have been no investigations of the role of PHGDH expression in bladder cancer (BC). In this investigation, we examined the clinical importance of PHDGH in BC. Furthermore, we asked whether PHGDH expression could be exploited for BC therapy. Finally, we investigated the regulatory mechanisms that modulated the expression of PHGDH. Using data from The Cancer Genome Atlas, we found that patients with high‐grade BC had significantly higher PHGDH expression levels than did those with low‐grade BC. In addition, patients with high PHGDH expression did not survive as long as those with low expression. PHGDH downregulation by si‐RNAs or an inhibitor in BC cell lines significantly inhibited proliferative ability and induced apoptosis. Furthermore, combined treatment using a PHGDH inhibitor and gemcitabine/cisplatin achieved synergistic tumor suppression compared to use of a single agent both in vitro as well as in vivo. Mechanistic analyses of PHGDH regulation showed that PHGDH expression might be associated with DNA copy number and hypomethylation in BC. These findings suggest novel therapeutic strategies could be used in BC. Finally, our data enhance our understanding of the role of PHGDH in BC.

Inhibition of Serine Metabolism Promotes Resistance to Cisplatin in Gastric Cancer

Background

Serine provides important precursors of protein, lipid, and nucleotide synthesis needed for tumor cell growth. Phosphoglycerate dehydrogenase (PHGDH), a key rate-limiting enzyme in the serine de novo synthesis pathway, is highly expressed in many tumor types (including gastric cancer) and negatively correlated with overall survival. Cisplatin is a chemotherapeutic drug commonly used in the treatment of gastric cancer. In this study, we mainly investigated the relationship between serine metabolism and resistance to cisplatin in gastric cancer cells, as well as the regulatory mechanism involved in this process.

Materials and Methods

We determined the effect of different concentrations of serine or a PHGDH inhibitor combined with cisplatin or oxaliplatin on the viability and apoptosis of SGC7901, BGC823, and MGC803 cells via the Cell Counting Kit-8 and Hoechst 33258 staining, respectively. Western blotting was utilized to detect the relative protein expression. Furthermore, we investigated DNA damage through the micrococcal nuclease sensitivity assay detected using agarose gels.

Results

We found that reduced concentrations of serine or inhibition of PHGDH hindered the toxicity and pro-apoptotic effects of cisplatin on gastric cancer cells. Moreover, the addition of serine could reverse the sensitivity of gastric cancer cells to cisplatin. Moreover, we found that DNA damage was reduced by treatment with PHGDH inhibitor NCT-503 or CBR-5884. Inhibition of serine metabolism induced a decrease in H3K4 tri-methylation, which was reversed by JIB-04 (inhibitor of H3K4 demethylase). The tolerance of gastric cancer cells to cisplatin was relieved by JIB-04. Through micrococcal nuclease experiments, we further found that inhibiting the activity of PHGDH strengthened chromatin tightness.

Conclusion

Inhibition of serine metabolism reduced H3K4 tri-methylation and increased the density of chromatin, which leads to decreased toxicity and pro-apoptotic effect of platinum chemotherapeutic drugs on gastric cancer cells.

The PHGDH enigma: Do cancer cells only need serine or also a redox modulator?

Upregulation of serine biosynthesis pathway activity is an increasingly apparent feature of many cancers. Most notably, the first rate-limiting enzyme of the pathway, phosphoglycerate dehydrogenase (PHGDH), is genomically amplified in some melanomas and breast cancers and can be transcriptionally regulated by various tumor suppressors and oncogenes. Yet emerging evidence suggests that serine-in particular, serine biosynthetic pathway activity-may promote cancer in ways beyond providing the building blocks to support cell proliferation. Here, we summarize how mammalian cells tightly control serine synthesis before discussing alternate ways in which increased serine synthetic flux through PHGDH may benefit cancer cells, such as maintenance of TCA cycle flux through alpha-ketoglutarate (αKG) and modulation of cellular redox balance. We will also provide an overview of the current landscape of therapeutics targeting serine synthesis and offer a perspective on future strategies.

The Role of D-3-Phosphoglycerate Dehydrogenase in Cancer

Serine, a non-essential amino acid, can be imported from the extracellular environment by transporters and de novo synthesized from glycolytic 3-phosphoglycerate (3-PG) in the serine biosynthetic pathway (SSP). It has been reported that active serine synthesis might be needed for the synthesis of proteins, lipids, and nucleotides and the balance of folate metabolism and redox homeostasis, which are necessary for cancer cell proliferation. Human D-3-phosphoglycerate dehydrogenase (PHGDH), the first and only rate-limiting enzyme in the de novo serine biosynthetic pathway, catalyzes the oxidation of 3-PG derived from glycolysis to 3-phosphohydroxypyruvate (3-PHP). PHGDH is highly expressed in tumors as a result of amplification, transcription, or its degradation and stability alteration, which dysregulates the serine biosynthesis pathway via metabolic enzyme activity to nourish tumors. And some recent researches reported that PHGDH promoted some tumors growth via non-metabolic way by upregulating target cancer-promoting genes. In this article, we reviewed the type, structure, expression and inhibitors of PHGDH, as well as the role it plays in cancer and tumor resistance to chemotherapy.

Links between cancer metabolism and cisplatin resistance

Cisplatin is one of the most potent and widely used chemotherapeutic agent in the treatment of several solid tumors, despite the high toxicity and the frequent relapse of patients due to the onset of drug resistance. Resistance to chemotherapeutic agents, either intrinsic or acquired, is currently one of the major problems in oncology. Thus, understanding the biology of chemoresistance is fundamental in order to overcome this challenge and to improve the survival rate of patients. Studies over the last 30 decades have underlined how resistance is a multifactorial phenomenon not yet completely understood. Recently, tumor metabolism has gained a lot of interest in the context of chemoresistance; accumulating evidence suggests that the rearrangements of the principal metabolic pathways within cells, contributes to the sensitivity of tumor to the drug treatment. In this review, the principal metabolic alterations associated with cisplatin resistance are highlighted. Improving the knowledge of the influence of metabolism on cisplatin response is fundamental to identify new possible metabolic targets useful for combinatory treatments, in order to overcome cisplatin resistance.

Effects of Galectin-1 on Biological Behavior in Cervical Cancer

Background: We previously revealed that the expression of galectin-1 (LGALS1) was significantly reduced after neoadjuvant chemotherapy treatment in cervical cancer patients. The objective of this study is to investigate the effects of LGALS1 expression on biological behaviors of cervical cancer cells.

Methods: Immunohistochemistry and immunocytochemistry were performed to detect the expression of LGALS1 in cervical cancer tissues and cells (SiHa and C33A). Western blot analysis was performed to evaluate the efficacy of lentivirus-mediated upregulation or downregulation of LGALS1 in cervical cancer cells. Cell viability and proliferation were detected by CCK-8 and BrdU assays, respectively. Annexin V-FITC/PI apoptosis detection kit was employed to measure the apoptosis of cervical cancer cells. Transwell invasion and migration assays were also conducted to explore the invasive and migratory capabilities of cervical cancer cells. The expression of apoptosis- (Bcl-2 and Bax), invasion- (MMP-2 and MMP-9), and migration-related (Fascin and Ezrin) proteins, were detected by Western blot analysis. Xenograft mouse model of cervical cancer was generated to explore whether LGALS1 overexpression could promote tumor growth in vivo.

Results: LGALS1 was overexpressed in cervical cancer tissues and cell lines compared to that in normal cervical tissues and epithelium cells. Upregulation of LGALS1 significantly promoted the cell proliferation, inhibited cell apoptosis, and enhanced the migratory and invasive abilities of both SiHa and C33A cells, whereas downregulation of LGALS1 led to the opposite results. The level of Bcl-2, MMP-2, MMP-9, Fascin, and Erzin expression was significantly upregulated in cervical cancer cells with LGALS1 overexpression, while converse results were obtained in LGALS1 knockdown cancer cells. In vivo study also showed that LGALS1 overexpression facilitated tumor growth of cervical cancer cells.

Conclusion: Overexpression of LGALS1 significantly promoted and enhanced the aggressive features of cervical cancer both in vitro and in vivo, which may be associated with high expression of Bcl-2, MMP-2, MMP-9, Fascin, and Erzin proteins.

Inhibition of EP2/EP4 prostanoid receptor-mediated signaling suppresses IGF-1-induced proliferation of pancreatic cancer BxPC-3 cells via upregulating γ-glutamyl cyclotransferase expression

Inhibition of prostaglandin E₂ signaling via EP2/EP4 prostanoid receptors suppresses Insulin-like growth factor (IGF)-1-induced proliferation of pancreatic cancer BxPC-3 cells. To better understand the mechanism of EP2/EP4 signaling for controlling cell proliferation, we performed metabolome analyses in BxPC-3 cells treated with IGF-1 alone or IGF-1 plus EP2/EP4 inhibitors. These analyses revealed increased g-aminobutyric acid and 5-oxoproline production following the addition of EP2/EP4 inhibitors to IGF-1-treated cells. The expression of a 5-oxoproline-catalyzing enzyme, γ-glutamylcyclotransferase (GGCT), was also upregulated by IGF-1 treatment and further enhanced by the addition of EP2/EP4 inhibitors. Knockdown of GGCT expression resulted in the loss of suppressive effects of EP2/EP4 inhibitors on IGF-1-induced BxPC-3 cell proliferation, whereas GGCT overexpression repressed the basal proliferation of BxPC-3 cells but did not affect the suppressive effects of EP2/EP4 inhibitors. To summarize, we propose a role for EP2/EP4 signaling in regulating IGF-1-induced cell proliferation, in which EP2/EP4 signaling represses IGF-1-induced GGCT expression, which mediates and whose amount controls a branch of IGF-1 signaling to promote cell proliferation via extracellular signal-regulated kinase phosphorylation.

Alcohol and DNA Methylation: An Epigenome-Wide Association Study in Blood and Normal Breast Tissue

The biological mechanisms driving associations between alcohol consumption and chronic diseases might include epigenetic modification of DNA methylation. We explored the hypothesis that alcohol consumption is associated with methylation in an epigenome-wide association study of blood and normal breast tissue DNA. Infinium HumanMethylation450 BeadChip (Illumina Inc., San Diego, California) array data on blood DNA methylation was examined in a discovery set of 2,878 non-Hispanic white women from the Sister Study (United States, 2004-2015) who provided detailed questionnaire information on lifetime alcohol use. Robust linear regression modeling was used to identify significant associations (false discovery rate of Q < 0.05) between the number of alcoholic drinks per week and DNA methylation at 5,458 cytosine-phosphate-guanine (CpG) sites. Associations were replicated (P < 0.05) for 677 CpGs in an independent set of 187 blood DNA samples from the Sister Study and for 628 CpGs in an independent set of 171 normal breast DNA samples; 1,207 CpGs were replicated in either blood or normal breast, with 98 CpGs replicated in both tissues. Individual gene effects were notable for phosphoglycerate dehydrogenase (PGHDH), peptidyl-prolyl cis-trans isomerase (PPIF), solute carrier 15 (SLC15), solute carrier family 43 member 1 (SLC43A1), and solute carrier family 7 member 11 (SLC7A11). We also found that high alcohol consumption was associated with significantly lower global methylation as measured by the average of CpGs on the entire array.

Downregulation of the long non‑coding RNA FOXD2‑AS1 inhibits cell proliferation, migration and invasion in osteosarcoma

Increasing amounts of long noncoding RNAs (lncRNAs) have been shown to be involved in the development of cancer. Recently, aberrant expression of the lncRNA forkhead box D2 adjacent opposite strand RNA1 (FOXD2-AS1) has been reported to be involved in the progression of several types of human cancer. However, the function and mechanism of FOXD2-AS1 in osteosarcoma (OS) are currently unclear. The present study aimed to investigate the function and mechanism of FOXD2-AS1 in OS. Firstly, it was revealed that the expression levels of FOXD2-AS1 were significantly upregulated in OS tissues and cells, compared with in adjacent tissues and normal cells, as determined using reverse transcription-quantitative polymerase chain reaction. Notably, the overall survival of patients with relatively high FOXD2-AS1 expression in OS tissues was significantly lower than that of patients with relatively low expression, as determined using Kaplan-Meier analysis. In addition, loss-of-function experiments were performed in vivo and in vitro to study the biological effects of FOXD2-AS1. The SOSP-9607 and U2OS OS cell lines were infected with lentivirus-mediated FOXD2-AS1 short hairpin RNA; subsequently, the alterations in cell phenotype and downstream molecules were evaluated. Knockdown of FOXD2-AS1 inhibited the proliferation, migration and invasion of OS cells. Furthermore, the number of cells in the S phase was significantly decreased, which was consistent with the results of the Cell Counting kit 8 proliferation assay. The expression levels of ribonucleotide reductase regulatory subunit M2 and phosphoglycerate dehydrogenase were decreased, as determined by western blotting, following FOXD2-AS1 knockdown. Finally, in a nude mouse model of tumorigenesis, it was revealed that, when FOXD2-AS1 expression was downregulated, tumor growth was significantly reduced and pulmonary metastatic nodules were markedly reduced. The results of the present study suggested that decreased FOXD2-AS1 expression may inhibit the growth, migration and invasion of tumor cells, and it may regulate downstream gene expression. In conclusion, these findings indicated that FOXD2-AS1 may be used as a potential therapeutic target and early tumor marker for the diagnosis and prognosis of OS.

Curcumin and its Potential for Systemic Targeting of Inflamm-Aging and Metabolic Reprogramming in Cancer

Pleiotropic effects of curcumin have been the subject of intensive research. The interest in this molecule for preventive medicine may further increase because of its potential to modulate inflamm-aging. Although direct data related to its effect on inflamm-aging does not exist, there is a strong possibility that its well-known anti-inflammatory properties may be relevant to this phenomenon. Curcumin's binding to various proteins, which was shown to be dependent on cellular oxidative status, is yet another feature for exploration in depth. Finally, the binding of curcumin to various metabolic enzymes is crucial to curcumin's interference with powerful metabolic machinery, and can also be crucial for metabolic reprogramming of cancer cells. This review offers a synthesis and functional links that may better explain older data, some observational, in light of the most recent findings on curcumin. Our focus is on its modes of action that have the potential to alleviate specific morbidities of the 21st century.

Ixocarpalactone A from dietary tomatillo inhibits pancreatic cancer growth by targeting PHGDH

3-Phosphoglycerate dehydrogenase (PHGDH) has been reported to associate with tumorigenesis in many cancers. IoxA, a natural withanolide obtained from dietary tomatillo (Physalis ixocarpa), was identified as the novel natural PHGDH inhibitor with high targeting and low toxicities for treatment of pancreatic cancers.

D-3-Phosphoglycerate Dehydrogenase

l-Serine is the immediate precursor of d-serine, a major agonist of the N-methyl-d-aspartate (NMDA) receptor. l-Serine is a pivotal amino acid since it serves as a precursor to a large number of essential metabolites besides d-serine. In all non-photosynthetic organisms, including mammals, a major source of l-serine is the phosphorylated pathway of l-serine biosynthesis. The pathway consists of three enzymes, d-3-phosphoglycerate dehydrogenase (PGDH), phosphoserine amino transferase (PSAT), and l-phosphoserine phosphatase (PSP). PGDH catalyzes the first step in the pathway by converting d-3-phosphoglycerate (PGA), an intermediate in glycolysis, to phosphohydroxypyruvate (PHP) concomitant with the reduction of NAD⁺. In some, but not all organisms, the catalytic activity of PGDH can be regulated by feedback inhibition by l-serine. Three types of PGDH can be distinguished based on their domain structure. Type III PGDHs contain only a nucleotide binding and substrate binding domain. Type II PGDHs contain an additional regulatory domain (ACT domain), and Type I PGDHs contain a fourth domain, termed the ASB domain. There is no consistent pattern of domain content that correlates with organism type, and even when additional domains are present, they are not always functional. PGDH deficiency results in metabolic defects of the nervous system whose systems range from microcephaly at birth, seizures, and psychomotor retardation. Although deficiency of any of the pathway enzymes have similar outcomes, PGDH deficiency is predominant. Dietary or intravenous supplementation with l-serine is effective in controlling seizures but has little effect on psychomotor development. An increase in PGDH levels, due to overexpression, is also associated with a wide array of cancers. In culture, PGDH is required for tumor cell proliferation, but extracellular l-serine is not able to support cell proliferation. This has led to the hypothesis that the pathway is performing some function related to tumor growth other than supplying l-serine. The most well-studied PGDHs are bacterial, primarily from Escherichia coli and Mycobacterium tuberculosis, perhaps because they have been of most interest mechanistically. However, the relatively recent association of PGDH with neuronal defects and human cancers has provoked renewed interest in human PGDH.

Knockdown of PHGDH potentiates 5-FU cytotoxicity in gastric cancer cells via the Bcl-2/Bax/caspase-3 signaling pathway

Gastric cancer (GC) is one of the most common malignancies in the world. Fluorouracil (5-FU) is widely used in the treatment of cancers, but resistance to 5-FU results in the failure of chemotherapy. Phosphoglycerate dehydrogenase (PHGDH) has been reported to play a vital role in the development of 5-FU resistance in cancer cells. However, the exact role of PHGDH and the underlying mechanisms for 5-FU resistance in GC cells remain elusive. In this study, PHGDH expression was much higher in the GC tissues of 5-FU-resistant patients than that in the GC tissues of 5-FU-sensitive patients. Moreover, the expression of PHGDH was obviously increased in BGC823/5-FU cells compared with that in BGC823 cells. 5-FU treatment significantly reduced the viability of BGC823/5-FU cells, in a dose- and time-dependent manner. Furthermore, 5-FU treatment inhibited the proliferation of BGC823/5-FU cells, as evidenced by decreased cell viability and reduced colony-forming ability. The knockdown of PHGDH made possible the inhibitory effect of 5-FU on the proliferation of BGC823/5-FU cells. Furthermore, 5-FU treatment promoted apoptosis of BGC823/5-FU cells, as indicated by increased numbers of TUNEL-positive cells and increased rates of apoptosis. Notably, the promoting effect of 5-FU on the apoptosis of BGC823/5-FU cells was markedly enhanced by PHGDH knockdown. Additionally, 5-FU treatment downregulated Bcl-2 expression and upregulated the expression of Bax and caspase-3, and this effect was remarkably enhanced by PHGDH knockdown. In conclusion, knockdown of PHGDH potentiates 5-FU cytotoxicity in GC cells via the Bcl-2/Bax/caspase-3 signaling pathway.

S100A9 regulates cisplatin chemosensitivity of squamous cervical cancer cells and related mechanism

Objective

Our previous research has shown that the expression of S100 calcium-binding protein A9 (S100A9) in tumor cells was associated with neoadjuvant chemotherapy sensitivity in cervical squamous cell carcinoma. In the present study, we altered the expression of S100A9 through infecting lentivirus, investigated its effect on the chemosensitivity to cisplatin of cervical cancer cells and then made a primary exploration of the involved mechanism.

Materials and methods

Lentivirus was employed to upregulate and downregulate S100A9 expression in SiHa cells. The protein expression level of apoptotic-related proteins Bcl-2 and Bax, drug resistance-related proteins multiple drug resistance protein 1 (MRP1), P glycoprotein (P-gp), glutathione-S-transferase-π (GST-π), lung resistance-related protein (LRP), and FOXO1 signaling pathway related proteins was detected by Western blot. The CCK-8 assay was used to examine chemosensitivity to cisplatin, and the proportion of apoptosis cells was analyzed by the flow cytometry.

Results

S100A9 overexpression could obviously increase the IC50 value of SiHa cells to cisplatin and decrease the apoptosis rate induced by cisplatin. Downregulation of S100A9 led to the opposite results. In S100A9 overexpression SiHa cells, the expression level of Bcl-2, LRP, GST-π, p-AKT, p-ERK, p-FOXO1, and Nanog was significantly increased, while FOXO1 expression was decreased. The opposite results were observed in S100A9 knockdown SiHa cells.

Conclusion

Downregulation of S100A9 could significantly increase apoptosis rate, resulting in enhancing sensitivity of SiHa cells to cisplatin, which may be related to Bcl-2, GST-π, and LRP protein and by altering the AKT/ERK-FOXO1-Nanog signaling pathway.

Expression of cleaved caspase-3 predicts good chemotherapy response but poor survival for patients with advanced primary triple-negative breast cancer

OBJECTIVE

To assess cleaved caspase-3 (CC3), Ki-67, and E-cadherin (E-cad) expression in relation to chemotherapy response and prognosis of patients with advanced primary triple-negative breast cancer (TNBC).

METHODS

CC3 expression was detected immunohistochemically in 67 pre-chemotherapy biopsy samples. Ki67 and E-cad levels were obtained from patients' medical records.

RESULTS

CC3-positivity (N = 32; 47.8%) was associated with a higher first-line chemotherapy overall response rate (ORR; P = 0.028) and second-line chemotherapy clinical benefit rate (CBR; P = 0.033). The Ki-67 high-risk group (N = 51; 76.1%) exhibited a reduced second-line chemotherapy CBR (P = 0.024). The E-cad negative group (N = 25; 37.3%) exhibited a lower first-line chemotherapy ORR (P = 0.044) and CBR (P<0.001), and a lower second-line chemotherapy CBR (P = 0.020). CC3, Ki-67, and E-cad were significant predictors of third-line chemotherapy ORR or CBR. Similar numbers of chemotherapy cycles were completed by the CC3-positive and -negative groups. The Ki-67 high-risk and E-cad negative groups completed fewer second-line chemotherapy cycles (P = 0.038) and fewer first-line chemotherapy cycles, respectively (P = 0.001). Kaplan-Meier analyses identified worse outcomes for the CC3-positive, Ki-67 high-risk, and E-cad negative groups than for their corresponding comparison groups (P<0.05). Multivariate Cox regression analysis identified CC3 expression and an absence of E-cad expression as independent survival factors (P<0.05).

CONCLUSIONS

Our CC3-positive group exhibited a better chemotherapy response, but a worse prognosis. The Ki-67 high-risk and E-cad negative groups exhibited both a worse chemotherapy response and worse prognosis.

Tissue-based Immunohistochemical Biomarker Accuracy in the Diagnosis of Malignant Glandular Lesions of the Uterine Cervix: A Systematic Review of the Literature and Meta-Analysis

Immunohistochemistry is widely used to support a pathology diagnosis of cervical adenocarcinoma despite the absence of a systematic review and meta-analysis of the published data. This systematic review and meta-analysis was performed to investigate the sensitivity and specificity of immunohistochemistry biomarkers in the tissue-based diagnosis of cervical adenocarcinoma histotypes compared with normal endocervix and benign glandular lesions. The systematic review and meta-analysis used a PICOT framework and QUADAS-2 to evaluate the quality of included studies. The literature search spanned 40 years and ended June 30, 2015. Abstracts of identified records were independently screened by 2 of the authors who then conducted a full-text review of selected articles. Sensitivity and specificity of immunohistochemistry expression in malignant glandular lesions of the cervix classified per WHO 2003 compared with 5 benign comparators (normal/benign endocervix, and benign endocervical, endometrioid, gastric, and mesonephric lesions) were calculated. Of 902 abstracts screened, 154 articles were selected for full review. Twenty-five articles with results for 36 biomarkers were included. The only biomarker with enough studies for a meta-analysis was p16 and the definition of positive p16 staining among them was variable. Nevertheless, any positive p16 expression was sensitive, ranging from 0.94 to 0.98 with narrow confidence intervals (CIs), for adenocarcinoma in situ (AIS) and mucinous adenocarcinomas in comparison with normal/benign endocervix and benign endocervical and endometrioid lesions. Specificity for AIS and mucinous adenocarcinomas was also high with narrow CIs compared with benign endocervical lesions. The specificity was high for AIS, 0.99 (0.24, 1.0), and mucinous adenocarcinoma, 0.95 (0.52, 1.0), compared with normal/benign endocervix but with wider CIs, and low with very wide CIs compared with benign endometrioid lesions: 0.31 (0.00, 0.99) and 0.34 (0.00, 0.99), respectively. Results from single studies showed that p16, p16/Ki67 dual stain, ProExC, CEA, ESA, HIK1083, Claudin 18, and ER loss in perilesional stromal cells were useful with high (≥0.75) sensitivity and specificity estimates in ≥1 malignant versus benign comparisons. None of the biomarkers had highly useful sensitivity and specificity estimates for AIS, mucinous adenocarcinomas, or minimal deviation adenocarcinoma/gastric adenocarcinoma compared with benign gastric or mesonephric lesions or for mesonephric carcinoma compared with normal/benign endocervix, benign endocervical, endometrial, or mesonephric lesions. Any expression of p16 supports a diagnosis of AIS and mucinous adenocarcinomas in comparison with normal/benign endocervix and benign endocervical lesions. The majority of studies did not separate mosaic/focal p16 staining from diffuse staining as a distinct pattern of p16 overexpression and this may have contributed to the poor performance of p16 in distinguishing AIS and mucinous adenocarcinomas from benign endometrioid lesions. Single studies support further investigation of 8 additional biomarkers that have highly useful sensitivity and specificity estimates for ≥1 malignant glandular lesions compared with ≥1 of the 5 benign comparators.

Validating and enabling phosphoglycerate dehydrogenase (PHGDH) as a target for fragment-based drug discovery in PHGDH-amplified breast cancer

3-Phosphoglycerate dehydrogenase (PHGDH) has recently been identified as an attractive target in cancer therapy as it links upregulated glycolytic flux to increased biomass production in cancer cells. PHGDH catalyses the first step in the serine synthesis pathway and thus diverts glycolytic flux into serine synthesis. We have used siRNA-mediated suppression of PHGDH expression to show that PHGDH is a potential therapeutic target in PHGDH-amplified breast cancer. Knockdown caused reduced proliferation in the PHGDH-amplified cell line MDA-MB-468, whereas breast cancer cells with low PHGDH expression or with elevated PHGDH expression in the absence of genomic amplification were not affected. As a first step towards design of a chemical probe for PHGDH, we report a fragment-based drug discovery approach for the identification of PHGDH inhibitors. We designed a truncated PHGDH construct that gave crystals which diffracted to high resolution, and could be used for fragment soaking. 15 fragments stabilising PHGDH were identified using a thermal shift assay and validated by X-ray crystallography and ITC competition experiments to exhibit 1.5-26.2 mM affinity for PHGDH. A structure-guided fragment growing approach was applied to the PHGDH binders from the initial screen, yielding greater understanding of the binding site and suggesting routes to achieve higher affinity NAD-competitive inhibitors.

Caspase-3 over-expression is associated with poor overall survival and clinicopathological parameters in breast cancer: a meta-analysis of 3091 cases

Caspase-3 is a vital executioner molecule during the apoptotic process. Numerous studies have revealed the close association of caspase-3 expression and breast cancer. Nevertheless, the prognostic value of caspase-3 expression for patients with breast cancer remains uncertain. To thoroughly analyze the prognostic effect of caspase-3 expression on the clinicopathological features and survival of breast cancer, we conducted this meta-analysis. With various search strategies, electronic databases were comprehensively searched. A total of 3091 patients from 21 studies were ultimately obtained. The analysis results indicated that increased expression of caspase-3 had a negative influence on the overall survival (OS) of breast cancer (HR = 1.73, 95%CI 1.12–2.67, P = 0.014). Subgroup analyses based on race revealed that the value of caspase-3 for evaluating patients’ OS was more useful in Asian patients (HR = 3.16, 95%CI 1.20–8.15, P = 0.020), and subgroup analyses based on study analytical methods revealed that caspase-3 was a risk factor for breast cancer patients in multivariate overall survival analyses (HR = 1.67, 95%CI 1.02–2.75, P = 0.044). As for the relationship between caspase-3 expression and breast cancer subtype as well as progression, caspase-3 might serve as a risk factor for the progestogen receptor (PR) and human epidermal growth factor receptor-2 (HER-2) subtypes (OR = 1.44, 95%CI 1.09–1.89, P = 0.010; OR = 1.76, 95%CI 1.18–2.62, P = 0.050, respectively) of breast cancer. However, no evidence showed that increased expression of caspase-3 was statistically correlated with tumor differentiation state (low/moderate or high), tumor TNM stage (I-II/III-IV) or lymph node metastasis (–/+). In conclusion, this meta-analysis revealed that increased caspase-3 expression was significantly associated with worse prognosis and two subtypes of breast cancer. More prospective studies are urgently needed to define the prognostic value of caspase-3 expression in patients with breast cancer.

PBX3 is associated with proliferation and poor prognosis in patients with cervical cancer

Pre-B-cell leukemia homeobox 3 (PBX3) is upregulated in various malignancies; however, the role of PBX3 in cervical cancer (CC) is unknown. The purpose of this study was to explore the expression characteristics, clinicopathological significance, and molecular biological function of PBX3 in CC. The expression levels of PBX3 were analyzed in CC cell lines and tumor specimens by real-time polymerase chain reaction (RT-PCR), Western blotting, and immunohistochemical staining. The clinicopathological characteristics associated with PBX3 expression were evaluated. An RNA interference approach was employed to suppress PBX3 expression in CC in vitro and in vivo, determine its role in cell proliferation and analyze its molecular function. We found that PBX3 expression was significantly upregulated in CC cell lines and clinical specimens compared with normal cells and adjacent nontumorous cervical tissues. PBX3 was an independent predictive factor of poor prognosis, and its expression was correlated with tumor diameter, pathological grading, lymph node metastasis, invasion depth, vascular invasion, and clinical stage of CC. Multivariate analysis suggested that PBX3 expression may represent an independent prognostic indicator of the survival of CC patients. CC patients with high PBX3 expression exhibited reduced overall survival compared with those with low PBX3 expression. Additionally, stable downregulation of PBX3 expression in CC cell lines suppressed cell proliferation and decreased p-AKT protein expression levels in vitro. Similarly, in vivo assays demonstrated that PBX3 downregulation in CC cells markedly inhibited tumor size and weight. Overall, we demonstrated that PBX3 can promote CC cell proliferation via the AKT signaling pathway and that it may serve as a prognostic marker. Our data indicate that inactivation of PBX3 may be an effective clinical treatment for CC.

PHGDH is an independent prognosis marker and contributes cell proliferation, migration and invasion in human pancreatic cancer

PURPOSE

To investigate the expression, clinical significance, biological function, and the potential mechanism of PHGDH in pancreatic cancer.

METHODS

The expression of PHGDH in human pancreatic cancer tissues and corresponding adjacent normal tissues were analyzed through immunohistochemistry staining. Simultaneously, the association between the PHGDH expression and the clinicopathological parameters and OS and DFS was evaluated. Human pancreatic cancer cell line BxPC-3 and SW1990 were selected to investigate the effect of PHGDH knockdown on cell proliferation, migration, and invasion. In addition, we performed western blot to assess the expression of cyclin B1, and cyclin D1, MMP-2, and MMP-9 protein.

RESULTS

Our results suggested that the expression of PHGDH is increased in pancreatic cancer compared with adjacent normal tissues and the increased expression of PHGDH is associated with tumor size, lymph node metastasis, and TNM state of pancreatic cancer patients. Moreover, the expression of PHGDH is an independent prognostic indicator for pancreatic cancer patients. In addition, we found that knockdown of PHGDH in pancreatic cancer cells inhibits the cell proliferation, migration, and invasion abilities by down-regulating the expression of cyclin B1, and cyclin D1, MMP-2, and MMP-9.

CONCLUSIONS

Our data indicated that the expression of PHGDH is increased in pancreatic cancer and is an independent molecular prognostic factor for pancreatic cancer patients. In addition, PHGDH controls cell proliferation, migration and invasion abilities. Therefore, PHGDH could serve as an important prognostic indicator and therapeutic target for pancreatic cancer.

Knockdown of ST6Gal-I increases cisplatin sensitivity in cervical cancer cells

Background

Sialyltransferase I (ST6Gal-I) is an enzyme involved in tumor metastasis that processes sialic acid precursors into their mature form, enabling them to regulate gene expression. However, the effect of ST6Gal-I on the biological behavior of cancer cells remain unclear. This study was the first to demonstrate the influence of ST6Gal-I on cisplatin sensitivity in cervical cancer cells.

Methods

Knockdown of ST6Gal-I was performed by shRNA and HeLa cells combination with cisplatin were tested.

Results

We showed that down-regulation of ST6Gal-I promoted cell apoptosis and inhibited proliferation and invasion in cervical cancer cells. Knockdown of ST6Gal-I by RNA interference increased the sensitivity of HeLa cells to cisplatin in vitro, and reduced tumor volume and suppressed subcutaneous tumor growth in response to cisplatin treatment in a xenograft mouse model in vivo.

Conclusions

The results provide new information that ST6Gal-I plays an important role in several biological or pathological processes including drug resistance in cervical cancer and may be a potential therapeutic target to improve the response to chemotherapy in cervical cancer patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2981-y) contains supplementary material, which is available to authorized users.

High Expression of PHGDH Predicts Poor Prognosis in Non-Small Cell Lung Cancer

Tumors have exceptionally high demands for energy and anabolism because of their rapid growth. The de novo serine synthesis pathway initiated by phosphoglycerate dehydrogenase (PHGDH) has been recognized as a hallmark of metabolic adaption in carcinogenesis. The oncogenic role and prognostic value of PHGDH have been investigated in multiple cancer types, including breast cancer, melanoma, cervical cancer, and colon cancer. Due to the importance of PHGDH in cancer, we attempted to determine the clinical significance of PHGDH in 319 patients with non–small cell lung cancer (NSCLC). We evaluated the mRNA and protein expression levels of PHGDH gene, using quantitative reverse transcriptase polymerase chain reaction and tissue array–based immunohistochemistry, respectively. Significantly increased PHGDH expression in mRNA and protein levels was identified in tumor tissues versus matched adjacent nontumor tissues. More interestingly, immunohistochemical expression of PHGDH was significantly associated with lymph node metastasis (P = .021) and TNM stage (P = .016). Kaplan-Meier survival analysis indicated that NSCLC patients with low levels of PHGDH outperformed patients with high levels of PHGDH regarding 5-year overall survival. Significantly longer survival in the former suggested the prognostic implication of PHGDH in NSCLC. Multivariate survival analysis using Cox regression model demonstrated that high PHGDH levels and advanced TNM stage (III + IV) were independent predictors of prognosis in NSCLC. Moreover, bioinformatics analysis confirmed the increase in PHGDH transcripts (data from The Cancer Genome Atlas) and its prognostic value (Kaplan-Meier plotter) in NSCLC. In conclusion, this study suggested the clinical implication of PHGDH in NSCLC. PHGDH may be a promising therapeutic target in NSCLC.

Phosphoglycerate dehydrogenase is a novel predictor for poor prognosis in gastric cancer

PURPOSE

Phosphoglycerate dehydrogenase (PHGDH) acts as a key metabolic enzyme in the rate-limiting step in serine biosynthesis and plays an important role in metastasis of several cancers. The aim of this study was to investigate the prognostic value of PHGDH in gastric cancer (GC).

METHODS

The messenger RNA expression of PHGDH was determined in 20 pairs of cancerous and adjacent nontumor tissues by real-time polymerase chain reaction. Immunohistochemistry of PHGDH was performed on tissue microarray, composed of 482 GC and 64 matched adjacent nontumor tissues acquired from surgery, 20 chronic gastritis, 18 intestinal metaplasia, and 31 low-grade and 66 high-grade intraepithelial neoplasias acquired through gastric endoscopic biopsy. Univariate and multivariate Cox proportional hazard models were used to perform survival analyses.

RESULTS

Both PHGDH messenger RNA and protein product exhibited GC tissue-preferred expression, when compared with benign tissues. The high PHGDH expression was significantly correlated with histological type (P=0.011), tumor stage (P=0.014), and preoperative carcinoembryonic antigen (P<0.001). A negative correlation was found between PHGDH expression and the 5-year survival rate of patients with GC. Furthermore, multivariate analysis indicated that PHGDH was an independent prognostic factor for outcome in GC.

CONCLUSION

PHGDH is important in predicting patient outcomes and is a potential target for the development of therapeutic approaches to GC.

Methionine-restricted diet inhibits growth of MCF10AT1-derived mammary tumors by increasing cell cycle inhibitors in athymic nude mice

Background

Dietary methionine restriction (MR) improves healthspan in part by reducing adiposity and by increasing insulin sensitivity in rodent models. The purpose of this study was to determine whether MR inhibits tumor progression in breast cancer xenograft model and breast cancer cell lines.

Methods

Athymic nude mice were injected with MCF10AT1 cells in Matrigel® and fed a diet containing either 0.86 % methionine (control fed, CF), or 0.12 % methionine (MR) for 12 weeks. Plasma amino acid concentrations were measured by UPLC, and proliferation and apoptosis were examined using RT-PCR, immunohistochemistry, and Cell Titer 96® Aqueous One Solution Cell Proliferation assay.

Results

Mice on the MR diet had reduced body weight and decreased adiposity. They also had smaller tumors when compared to the mice bearing tumors on the CF diet. Plasma concentrations of the sulfur amino acids (methionine, cysteine, and taurine) were reduced, whereas ornithine, serine, and glutamate acid were increased in mice on the MR diet. MR mice exhibited decreased proliferation and increased apoptosis in cells that comprise the mammary glands and tumors of mice. Elevated expression of P21 occurred in both MCF10AT1-derived tumor tissue and endogenously in mammary gland tissue of MR mice. Breast cancer cell lines MCF10A and MDA-MB-231 grown in methionine-restricted cysteine-depleted media for 24 h also up-regulated P21 and P27 gene expression, and MDA-MB-231 cells had decreased proliferation.

Conclusion

MR hinders cancer progression by increasing cell cycle inhibitors that halt cell cycle progression. The application of MR in a clinical setting may provide a delay in the progression of cancer, which would provide more time for conventional cancer therapies to be effective.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2367-1) contains supplementary material, which is available to authorized users.

Increased Expression of PHGDH and Prognostic Significance in Colorectal Cancer

Phosphoglycerate dehydrogenase (PHGDH) plays an essential role in cancer-specific metabolic reprogramming. It has been reported as a putative metabolic oncogene in several types of human malignant tumors, such as breast cancer and melanoma. To date, PHGDH expression in colorectal cancer (CRC) as well as its association with clinicopathological characteristics and prognostic implication remain undetermined. In this study, we determined the PHGDH protein expression using tissue microarray immunohistochemistry (TMA-IHC) on 193 pairs of formalin-fixed, paraffin-embedded specimens of CRC and adjacent tissues, 25 chronic colitis, 41 low-, and 19 high-grade intraepithelial neoplasia specimens, and we also determined PHGDH mRNA level using quantitative reverse transcription PCR (qRT-PCR) on additional 23 pairs of fresh CRC tissues and adjacent tissues. We found that both PHGDH mRNA and protein was highly expressed in tumor tissues in comparison with matched adjacent non-tumor tissues, and high PHGDH protein expression was correlated with advanced TNM stage (P = .038) and larger tumor (P = .001). Multivariate Cox regression analysis showed that PHGDH protein expression (HR = 2.285, 95% CI = 1.18 to 4.41, P = .014), tumor differentiation (HR = .307, 95% CI = .154 to 0.609, P = .001), and TNM stage (HR = 1.791, 95% CI = 1.125 to 2.85, P = .014) were independent prognostic factors in CRC. Kaplan-Meier survival curves and log rank test showed that high PHGDH protein expression contributed to poor outcome in CRC patients (P < .001). In conclusion, these results suggest that assessment of PHGDH expression could be useful in identifying a high-risk subgroup of CRC.

Amino acid management in cancer

Amino acids have a dual role in cellular metabolism, as they are both the building blocks for protein synthesis and intermediate metabolites which fuel other biosynthetic reactions. Recent work has demonstrated that deregulation of both arms of amino acid management are common alterations seen in cancer. Among the most highly consumed nutrients by cancer cells are the amino acids glutamine and serine, and the biosynthetic pathways that metabolize them are required in various cancer subtypes and the object of current efforts to target cancer metabolism. Also altered in cancer are components of the machinery which sense amino acid sufficiency, nucleated by the mechanistic target of rapamycin (mTOR), a key regulator of cell growth via modulation of key processes including protein synthesis and autophagy. The precise ways in which altered amino acid management supports cellular transformation remain mostly elusive, and a fuller mechanistic understanding of these processes will be important for efforts to exploit such alterations for cancer therapy.