Potential blockade of the human voltage-dependent anion channel by MoS2 nanoflakes.

Despite significant interest in molybdenum disulfide (MoS2) nanomaterials, particularly in biomedicine, their biological effects have been understudied. Here, we explored the effect of MoS2 nanoflakes on the ubiquitous mitochondrial porin voltage-dependent anion channel (VDAC1), using a combined computational and functional approach. All-atomic molecular dynamics simulations suggest that MoS2 nanoflakes make specific contact interactions with human VDAC1. We show that the initial contacts between hVDAC1 and the nanoflake are hydrophobic but are subsequently enhanced by a complex interplay of van der Waals (vdW), hydrophobic and electrostatic interactions in the equilibrium state. Moreover, the MoS2 nanoflake can insert into the lumen of the hVDAC1 pore. Free-energy calculations computed by the potential of mean force (PMF) verify that the blocked configuration of the MoS2-hVDAC1 complex is more energetically favorable than the non-blocked binding mode. Consistent with these predictions, we showed that MoS2 depolarizes the mitochondrial membrane potential (Ψm) and causes a decrease in the viability of mammalian tissue culture cells. These findings might shed new light on the potential biological effect of MoS2 nanomaterials.

Phosphoinositide control of membrane protein function: a frontier led by studies on ion channels.

Anionic phospholipids are critical constituents of the inner leaflet of the plasma membrane, ensuring appropriate membrane topology of transmembrane proteins. Additionally, in eukaryotes, the negatively charged phosphoinositides serve as key signals not only through their hydrolysis products but also through direct control of transmembrane protein function. Direct phosphoinositide control of the activity of ion channels and transporters has been the most convincing case of the critical importance of phospholipid-protein interactions in the functional control of membrane proteins. Furthermore, second messengers, such as [Ca(2+)]i, or posttranslational modifications, such as phosphorylation, can directly or allosterically fine-tune phospholipid-protein interactions and modulate activity. Recent advances in structure determination of membrane proteins have allowed investigators to obtain complexes of ion channels with phosphoinositides and to use computational and experimental approaches to probe the dynamic mechanisms by which lipid-protein interactions control active and inactive protein states.

Effect of lncRNA HOXA11-AS1 on adipocyte differentiation in human adipose-derived stem cells.

AIMS: To determine the role of lncRNA HOXA11-AS1 on adipocyte differentiation. METHODS: Human adipose-derived stem cells (hADSCs) were isolated from adipose tissues of patients and cultured in vitro, followed by knockdown of HOXA11-AS1. Then, adipocyte differentiation and expression of adipogenic-related genes (CEBP-α, DGAT2, CIDEC, and perilipin) were measured by RT-qPCR and Western blot. RESULTS: We demonstrated that knockdown of HOXA11-AS1 inhibited adipocyte differentiation, leading to suppression of adipogenic-related gene (CEBP-α, DGAT2, CIDEC, and perilipin) transcription, as well as decreased lipid accumulation in hADSCs. In addition, lncRNA HOXA11-AS1 was highly expressed in obese patients and significantly increased during the process of adipocyte differentiation. CONCLUSION: The results provide new insight into the molecular mechanism by which lncRNA HOXA11-AS1 is involved in adipogenesis and may have implications for the treatment of obesity and associated disorders.

A Critical Gating Switch at a Modulatory Site in Neuronal Kir3 Channels.

Inwardly rectifying potassium channels enforce tight control of resting membrane potential in excitable cells. The Kir3.2 channel, a member of the Kir3 subfamily of G-protein-activated potassium channels (GIRKs), plays several roles in the nervous system, including key responsibility in the GABAB pathway of inhibition, in pain perception pathways via opioid receptors, and is also involved in alcoholism. PKC phosphorylation acts on the channel to reduce activity, yet the mechanism is incompletely understood. Using the heterologous Xenopus oocyte system combined with molecular dynamics simulations, we show that PKC modulation of channel activity is dependent on Ser-196 in Kir3.2 such that, when this site is phosphorylated, the channel is less sensitive to PKC inhibition. This reduced inhibition is dependent on an interaction between phospho-Ser (SEP)-196 and Arg-201, reducing Arg-201 interaction with the sodium-binding site Asp-228. Neutralization of either SEP-196 or Arg-201 leads to a channel with reduced activity and increased sensitivity to PKC inhibition. This study clarifies the role of Ser-196 as an allosteric modulator of PKC inhibition and suggests that the SEP-196/Arg-201 interaction is critical for maintaining maximal channel activity. SIGNIFICANCE STATEMENT: The inwardly rectifying potassium 3.2 (Kir3.2) channel is found principally in neurons that regulate diverse brain functions, including pain perception, alcoholism, and substance addiction. Activation or inhibition of this channel leads to changes in neuronal firing and chemical message transmission. The Kir3.2 channel is subject to regulation by intracellular signals including sodium, G-proteins, ethanol, the phospholipid phosphatidylinositol bis-phosphate, and phosphorylation by protein kinases. Here, we take advantage of the recently published structure of Kir3.2 to provide an in-depth molecular view of how phosphorylation of a specific residue previously thought to be the target of PKC promotes channel gating and acts as an allosteric modulator of PKC-mediated inhibition.

Selective phosphorylation modulates the PIP2 sensitivity of the CaM-SK channel complex.

Phosphatidylinositol bisphosphate (PIP2) regulates the activities of many membrane proteins, including ion channels, through direct interactions. However, the affinity of PIP2 is so high for some channel proteins that its physiological role as a modulator has been questioned. Here we show that PIP2 is a key cofactor for activation of small conductance Ca2+-activated potassium channels (SKs) by Ca(2+)-bound calmodulin (CaM). Removal of the endogenous PIP2 inhibits SKs. The PIP2-binding site resides at the interface of CaM and the SK C terminus. We further demonstrate that the affinity of PIP2 for its target proteins can be regulated by cellular signaling. Phosphorylation of CaM T79, located adjacent to the PIP2-binding site, by casein kinase 2 reduces the affinity of PIP2 for the CaM-SK channel complex by altering the dynamic interactions among amino acid residues surrounding the PIP2-binding site. This effect of CaM phosphorylation promotes greater channel inhibition by G protein-mediated hydrolysis of PIP2.

Structural determinants of phosphatidylinositol 4,5-bisphosphate (PIP2) regulation of BK channel activity through the RCK1 Ca2+ coordination site.

Big or high conductance potassium (BK) channels are activated by voltage and intracellular calcium (Ca(2+)). Phosphatidylinositol 4,5-bisphosphate (PIP2), a ubiquitous modulator of ion channel activity, has been reported to enhance Ca(2+)-driven gating of BK channels, but a molecular understanding of this interplay or even of the PIP2 regulation of this channel's activity remains elusive. Here, we identify structural determinants in the KDRDD loop (which follows the αA helix in the RCK1 domain) to be responsible for the coupling between Ca(2+) and PIP2 in regulating BK channel activity. In the absence of Ca(2+), RCK1 structural elements limit channel activation through a decrease in the channel's PIP2 apparent affinity. This inhibitory influence of BK channel activation can be relieved by mutation of residues that (a) connect either the RCK1 Ca(2+) coordination site (Asp(367) or its flanking basic residues in the KDRDD loop) to the PIP2-interacting residues (Lys(392) and Arg(393)) found in the αB helix or (b) are involved in hydrophobic interactions between the αA and αB helix of the RCK1 domain. In the presence of Ca(2+), the RCK1-inhibitory influence of channel-PIP2 interactions and channel activity is relieved by Ca(2+) engaging Asp(367). Our results demonstrate that, along with Ca(2+) and voltage, PIP2 is a third factor critical to the integral control of BK channel activity.

PIP2 controls voltage-sensor movement and pore opening of Kv channels through the S4-S5 linker.

Voltage-gated K(+) (Kv) channels couple the movement of a voltage sensor to the channel gate(s) via a helical intracellular region, the S4-S5 linker. A number of studies link voltage sensitivity to interactions of S4 charges with membrane phospholipids in the outer leaflet of the bilayer. Although the phospholipid phosphatidylinositol-4,5-bisphosphate (PIP(2)) in the inner membrane leaflet has emerged as a universal activator of ion channels, no such role has been established for mammalian Kv channels. Here we show that PIP(2) depletion induced two kinetically distinct effects on Kv channels: an increase in voltage sensitivity and a concomitant decrease in current amplitude. These effects are reversible, exhibiting distinct molecular determinants and sensitivities to PIP(2). Gating current measurements revealed that PIP(2) constrains the movement of the sensor through interactions with the S4-S5 linker. Thus, PIP(2) controls both the movement of the voltage sensor and the stability of the open pore through interactions with the linker that connects them.

Ku70 Binding to YAP Alters PARP1 Ubiquitination to Regulate Genome Stability and Tumorigenesis.

Yes-associated protein (YAP) is a central player in cancer development, with functions extending beyond its recognized role in cell growth regulation. Recent work has identified a link between YAP/transcriptional coactivator with PDZ-binding motif (TAZ) and the DNA damage response. Here, we investigated the mechanistic underpinnings of the cross-talk between DNA damage repair and YAP activity. Ku70, a key component of the nonhomologous end joining pathway to repair DNA damage, engaged in a dynamic competition with TEAD4 for binding to YAP, limiting the transcriptional activity of YAP. Depletion of Ku70 enhanced interaction between YAP and TEAD4 and boosted YAP transcriptional capacity. Consequently, Ku70 loss enhanced tumorigenesis in colon cancer and hepatocellular carcinoma (HCC) in vivo. YAP impeded DNA damage repair and elevated genome instability by inducing PARP1 degradation through the SMURF2-mediated ubiquitin-proteasome pathway. Analysis of samples from patients with HCC substantiated the link between Ku70 expression, YAP activity, PARP1 levels, and genome instability. In conclusion, this research provides insight into the mechanistic interactions between YAP and key regulators of DNA damage repair, highlighting the role of a Ku70-YAP-PARP1 axis in preserving genome stability. Significance: Increased yes-associated protein transcriptional activity stimulated by loss of Ku70 induces PARP1 degradation by upregulating SMURF2 to inhibit DNA damage, driving genome instability and tumorigenesis.

Building KCNQ1/KCNE1 channel models and probing their interactions by molecular-dynamics simulations.

The slow delayed rectifier (I(KS)) channel is composed of KCNQ1 (pore-forming) and KCNE1 (auxiliary) subunits, and functions as a repolarization reserve in the human heart. Design of I(KS)-targeting anti-arrhythmic drugs requires detailed three-dimensional structures of the KCNQ1/KCNE1 complex, a task made possible by Kv channel crystal structures (templates for KCNQ1 homology-modeling) and KCNE1 NMR structures. Our goal was to build KCNQ1/KCNE1 models and extract mechanistic information about their interactions by molecular-dynamics simulations in an explicit lipid/solvent environment. We validated our models by confirming two sets of model-generated predictions that were independent from the spatial restraints used in model-building. Detailed analysis of the molecular-dynamics trajectories revealed previously unrecognized KCNQ1/KCNE1 interactions, whose relevance in I(KS) channel function was confirmed by voltage-clamp experiments. Our models and analyses suggest three mechanisms by which KCNE1 slows KCNQ1 activation: by promoting S6 bending at the Pro hinge that closes the activation gate; by promoting a downward movement of gating charge on S4; and by establishing a network of electrostatic interactions with KCNQ1 on the extracellular surface that stabilizes the channel in a pre-open activated state. Our data also suggest how KCNE1 may affect the KCNQ1 pore conductance.

The cytosolic GH loop regulates the phosphatidylinositol 4,5-bisphosphate-induced gating kinetics of Kir2 channels.

Inwardly rectifying K(+) (Kir) channels set the resting membrane potential and regulate cellular excitability. The activity of Kir channels depends critically on the phospholipid PIP(2). The molecular mechanism by which PIP(2) regulates Kir channel gating is poorly understood. Here, we utilized a combination of computational and electrophysiological approaches to discern structural elements involved in regulating the PIP(2)-induced gating kinetics of Kir2 channels. We identify a novel role for the cytosolic GH loop. Mutations that directly or indirectly affect GH loop flexibility (e.g. V223L, E272G, D292G) increase both the on- and especially the off-gating kinetics. These effects are consistent with a model in which competing interactions between the CD and GH loops for the N terminus regulate the gating of the intracellular G loop gate.

N-geranyl cyclopropyl-carboximide modulates salty and umami taste in humans and animal models.

Effects of N-geranyl cyclopropyl-carboxamide (NGCC) and four structurally related compounds (N-cyclopropyl E2,Z6-nonadienamide, N-geranyl isobutanamide, N-geranyl 2-methylbutanamide, and allyl N-geranyl carbamate) were evaluated on the chorda tympani (CT) nerve response to NaCl and monosodium glutamate (MSG) in rats and wild-type (WT) and TRPV1 knockout (KO) mice and on human salty and umami taste intensity. NGCC enhanced the rat CT response to 100 mM NaCl + 5 µM benzamil (Bz; an epithelial Na(+) channel blocker) between 1 and 2.5 µM and inhibited it above 5 µM. N-(3-methoxyphenyl)-4-chlorocinnamid (SB-366791, a TRPV1t blocker) inhibited the NaCl+Bz CT response in the absence and presence of NGCC. Unlike the WT mice, no NaCl+Bz CT response was observed in TRPV1 KO mice in the absence or presence of NGCC. NGCC enhanced human salt taste intensity of fish soup stock containing 60 mM NaCl at 5 and 10 µM and decreased it at 25 µM. Rat CT responses to NaCl+Bz and human salt sensory perception were not affected by the above four structurally related compounds. Above 10 µM, NGCC increased the CT response to MSG+Bz+SB-366791 and maximally enhanced the response between 40 and 60 µM. Increasing taste cell Ca(2+) inhibited the NGCC-induced increase but not the inosine monophosphate-induced increase in glutamate response. Addition of 45 µM NGCC to chicken broth containing 60 mM sodium enhanced the human umami taste intensity. Thus, depending upon its concentration, NGCC modulates salt taste by interacting with the putative TRPV1t-dependent salt taste receptor and umami taste by interacting with a Ca(2+)-dependent transduction pathway.

Rare-Earth-Zirconate Porous High-Entropy Ceramics with Unique Pore Structures for Thermal Insulating Applications.

Porous high-entropy ceramics are a new alternative material for thermal insulation. Their better stability and low thermal conductivity are due to lattice distortion and unique pore structures. In this work, rare-earth-zirconate ((La0.25Eu0.25Gd0.25Yb0.25)2(Zr0.75Ce0.25)2O7) porous high-entropy ceramics were fabricated by a tert-butyl alcohol (TBA)-based gel-casting method. The regulation of pore structures was realized through changing different initial solid loadings. The XRD, HRTEM, and SAED results showed that the porous high-entropy ceramics had a single fluorite phase without impurity phases, exhibiting high porosity (67.1-81.5%), relatively high compressive strength (1.02-6.45 MPa) and low thermal conductivity (0.0642-0.1213 W/(m·K)) at room temperature. Porous high-entropy ceramics with 81.5% porosity demonstrated excellent thermal properties, showing a thermal conductivity of 0.0642 W/(m·K) at room temperature and 0.1467 W/(m·K) at 1200 °C. The unique pore structure with a micron size contributed to their excellent thermal insulating performance. The present work provides the prospect that rare-earth-zirconate porous high-entropy ceramics with tailored pore structures are expected to be thermal insulation materials.

STAU1 promotes adipogenesis by regulating the alternative splicing of Pparγ2 mRNA.

During adipocyte differentiation, specific genes such as peroxisome proliferator-activated receptor γ (PPARγ) are transcribed and post-transcriptional pre-mRNA is processed into mature mRNA. Since Pparγ2 pre-mRNAs contain putative binding sites for STAUFEN1 (STAU1), which can affect the alternative splicing of pre-mRNA, we hypothesized that STAU1 might regulate the alternative splicing of Pparγ2 pre-mRNA. In this study, we found that STAU1 affects the differentiation of 3 T3-L1 pre-adipocytes. Through RNA-seq analysis, we confirmed that STAU1 can regulate alternative splicing events during adipocyte differentiation, mainly through exon skipping, which suggests that STAU1 is mainly involved in exon splicing. In addition, gene annotation and cluster analysis revealed that the genes affected by alternative splicing were enriched in lipid metabolism pathways. We further demonstrated that STAU1 can regulate the alternative splicing of Pparγ2 pre-mRNA and affect the splicing of exon E1 through RNA immuno-precipitation, photoactivatable ribonucleotide enhanced crosslinking and immunoprecipitation, and sucrose density gradient centrifugation assays. Finally, we confirmed that STAU1 can regulate the alternative splicing of Pparγ2 pre-mRNA in stromal vascular fraction cells. In summary, this study improves our understanding of the function of STAU1 in adipocyte differentiation and the regulatory network of adipocyte differentiation-related gene expression.

Identification of driving genes of familial adenomatous polyposis by differential gene expression analysis and weighted gene co-expression network analysis.

BACKGROUND: Despite the advancement of new screening strategies and the advances in pharmacological therapies, the cancerization rates of familial adenomatous polyposis (FAP) are stable and even increased in the last years. Therefore, it necessitates additional research to characterize and understand the underlying mechanisms of FAP. OBJECTIVE: To determine the genes that drive the pathogenesis of familial adenomatous polyposis (FAP). METHODS: We performed on a cohort (GSE111156) gene profile, which consist of four group of gene expressions (the gene expressions of cancer, adenoma and normal tissue of duodenal cancer from patients with FAP were defined as Case N, Case A and Case C respectively, while that of adenoma tissue from patients with FAP who did not have duodenal cancer was Ctrl A). Tracking Tumor Immunophenotype (TIP) website was applied to reveal immune infiltration profile and signature genes of FAP. We merged the genes of key module (pink and midnight module) with signature genes to obtained the biomarkers related with FAP pathogenesis. The expression of these five biomarkers in FAP intratumoral region (IT) and tumor rim (TR) was detected with Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR). RESULTS: In total, 220, 23 and 63 DEGs were determined in Cases C, A and N, in comparison to Ctrl A. In total, 196 and 10 DEGs were determined in Cases C and A, separately, as compared to Case N. A total of four biomarkers including CCL5, CD3G, CD2 and TLR3 were finally identified associated with pink module, while only one biomarker (KLF2) associated with midnight module was identified. All biomarkers were evidently raised in FAP IT tissues utilizing qRT-PCR. CONCLUSION: We identified five potential biomarkers for pathogenesis of FAP to understand the fundamental mechanisms of FAP progression and revealed some probable targets for the diagnosis or treatment of FAP.

Somatic mutation profiling, tumor-infiltrating leukocytes, tertiary lymphoid structures and PD-L1 protein expression in HER2-amplified colorectal cancer.

The status of human epidermal growth factor receptor 2 (HER2) for the prognosis in colorectal cancer (CRC) is controversial, and the characteristics of the somatic mutation spectrum, tumor-infiltrating leukocytes, tertiary lymphoid structures and PD-L1 protein are unknown in HER2-amplified colorectal cancer (HACC). In order to explore these characteristics along with their correlation with clinicopathological factors and prognosis in HACC. Samples of 812 CRC patients was collected. After immunohistochemistry (IHC), 59 of 812 were found to be HER2-positive, then 26 of 59 samples were further determined to be HER2 amplification by fluorescence in situ hybridization (FISH). Somatic mutation profiling of HACC was analysed using whole exome sequencing (WES). Multiplex fluorescence immunohistochemistry (mIHC) was used for tumor-infiltrating leukocytes and tertiary lymphoid structures (TLSs), while PD-L1 protein was detected by IHC. Our results indicate that the detection rates of HER2 positivity by IHC and FISH were 7.3% and 3.2% respectively, and HER2 amplification is correlated with distant tumour metastasis. The somatic mutation profiling revealed no differences between HACC and HER2-negative CRC. However, TP 53 strongly correlated with poor prognosis in HACC. Furthermore, tumor-infiltrating T cells and TLSs in the tumor immune microenvironment, as well as PD-L1 expression, were higher in HACC than in HER2-negative controls. However, none of them were associated with the prognosis of HACC. In all, HER2 amplification is correlated with distant metastasis and TP53 gene mutation may be a potential protective mechanism of HACC.

The molecular mechanism by which PIP(2) opens the intracellular G-loop gate of a Kir3.1 channel.

Inwardly rectifying potassium (Kir) channels are characterized by a long pore comprised of continuous transmembrane and cytosolic portions. A high-resolution structure of a Kir3.1 chimera revealed the presence of the cytosolic (G-loop) gate captured in the closed or open conformations. Here, we conducted molecular-dynamics simulations of these two channel states in the presence and absence of phosphatidylinositol bisphosphate (PIP(2)), a phospholipid that is known to gate Kir channels. Simulations of the closed state with PIP(2) revealed an intermediate state between the closed and open conformations involving direct transient interactions with PIP(2), as well as a network of transitional inter- and intrasubunit interactions. Key elements in the G-loop gating transition involved a PIP(2)-driven movement of the N-terminus and C-linker that removed constraining intermolecular interactions and led to CD-loop stabilization of the G-loop gate in the open state. To our knowledge, this is the first dynamic molecular view of PIP(2)-induced channel gating that is consistent with existing experimental data.

Molecular mechanism of species-dependent sweet taste toward artificial sweeteners.

The heterodimer of Tas1R2 and Tas1R3 is a broadly acting sweet taste receptor, which mediates mammalian sweet taste toward natural and artificial sweeteners and sweet-tasting proteins. Perception of sweet taste is a species-selective physiological process. For instance, artificial sweeteners aspartame and neotame taste sweet to humans, apes, and Old World monkeys but not to New World monkeys and rodents. Although specific regions determining the activation of the receptors by these sweeteners have been identified, the molecular mechanism of species-dependent sweet taste remains elusive. Using human/squirrel monkey chimeras, mutagenesis, and molecular modeling, we reveal that the different responses of mammalian species toward the artificial sweeteners aspartame and neotame are determined by the steric effect of a combination of a few residues in the ligand binding pocket. Residues S40 and D142 in the human Tas1R2, which correspond to residues T40 and E142 in the squirrel monkey Tas1R2, were found to be the critical residues for the species-dependent difference in sweet taste. In addition, human Tas1R2 residue I67, which corresponds to S67 in squirrel monkey receptor, modulates the higher affinity of neotame than of aspartame. Our studies not only shed light on the molecular mechanism of species-dependent sweet taste toward artificial sweeteners, but also provide guidance for designing novel effective artificial sweet compounds.

Functional characterization of the heterodimeric sweet taste receptor T1R2 and T1R3 from a New World monkey species (squirrel monkey) and its response to sweet-tasting proteins.

The family C G protein-coupled receptor (GPCR) T1R2 and T1R3 heterodimer functions as a broadly acting sweet taste receptor. Perception of sweet taste is a species-dependent physiological process. It has been widely reported that New World monkeys and rodents are not able to perceive some of the artificial sweeteners and sweet-tasting proteins that can be perceived by humans, apes, and Old World monkeys. Until now, only the sweet receptors of humans, mice and rats have been functionally characterized. Here we report characterization of the sweet taste receptor (T1R2/T1R3) from a species of New World primate, squirrel monkey. Our results show that the heterodimeric receptor of squirrel monkey does not respond to artificial sweeteners aspartame, neotame, cyclamate, saccharin and sweet-tasting protein monellin, but surprisingly, it does respond to thaumatin at high concentrations (>18 µM). This is the first report demonstrating that species of New World monkey can perceive some specific sweet-tasting proteins. Furthermore, the sweet receptor of squirrel monkey responses to the such sweeteners cannot be inhibited by the sweet inhibitor lactisole. We compared the response differences of the squirrel monkey and human receptors and found that the residues in T1R2 determine species-dependent sweet taste toward saccharin, while the residues in either T1R2 or T1R3 are responsible for the sweet taste difference between humans and squirrel monkeys toward monellin. Molecular models indicated that electrostatic properties of the receptors probably mediate the species-dependent response to sweet-tasting proteins.

Predicting protein interactions by Brownian dynamics simulations.

We present a newly adapted Brownian-Dynamics (BD)-based protein docking method for predicting native protein complexes. The approach includes global BD conformational sampling, compact complex selection, and local energy minimization. In order to reduce the computational costs for energy evaluations, a shell-based grid force field was developed to represent the receptor protein and solvation effects. The performance of this BD protein docking approach has been evaluated on a test set of 24 crystal protein complexes. Reproduction of experimental structures in the test set indicates the adequate conformational sampling and accurate scoring of this BD protein docking approach. Furthermore, we have developed an approach to account for the flexibility of proteins, which has been successfully applied to reproduce the experimental complex structure from the structure of two unbounded proteins. These results indicate that this adapted BD protein docking approach can be useful for the prediction of protein-protein interactions.

The prognostic and clinicopathological roles of microsatellite instability, PD-L1 expression and tumor-infiltrating leukocytes in familial adenomatous polyposis.

BACKGROUND: Microsatellite instability, programmed death-ligand 1 and tumor-infiltrating leukocytes are prognostic biomarkers in colorectal cancer but unknown toward familial adenomatous polyposis. AIM: To investigate the prognostic and clinicopathological roles of microsatellite instability, programmed death-ligand 1 and tumor-infiltrating leukocytes in familial adenomatous polyposis. METHODS: Clinical data and paraffin embedded tissues from 45 familial adenomatous polyposis patients were collected. Microsatellite instability was detected by immunohistochemistry and polymerase chain reaction. Programmed death-ligand 1 was detected by immunohistochemistry. Tumor-infiltrating leukocytes comprising CD8+ T cells, M1 and M2 tumor associated macrophages, CD56bright and CD56dim natural killer cells were analyzed using multiple fluorescence immunohistochemistry. RESULTS: Microsatellite instability high was noted in 6 samples but not associated with overall survival or progression-free survival. Programmed death-ligand 1 is negative on tumor cells but positive on tumor-infiltrating leukocytes, and positive programmed death-ligand 1 expression on tumor-infiltrating leucocytes is associated with overall survival. Low CD56bright natural killer cell infiltration was associated with longer progression-free survival and was an independent prognostic factor in FAP. CONCLUSION: For familial adenomatous polyposis, microsatellite instability high can be found but has no correlation with prognosis; programmed death-ligand 1 on tumor-infiltrating leukocytes is related with overall survival; CD56bright natural killer cell is an independent prognostic factor associating with longer progression-free survival.