Medical genetics is a basic medical course that discusses the diagnosis, prevention and treatment of diseases in relation with genetic factors. This course requires students who have abilities of strong logical thinking, independent thinking, problem analyzing and solving. Single "cramming" teaching is difficult to mobilize students' autonomous learning, and hardly achieves teaching effect of medical genetics. Teaching of case-based discussion breaks passive teaching mode in traditional class. The teacher throws out typically clinical cases. The students prepare materials around relevant problems of cases, and carry out class discussion. Then, key and difficult points of the course are integrated in teaching and learning interaction, which reaches a remarkable effect of teaching. Since 2013, the teaching and research group has carried out teaching of case-based discussion in undergraduates majoring in clinical medicine. In this paper, we screen and sort clinical cases on the basis of course teaching plan and case-based discussion in the teaching of medical genetics. The cases are summarized into 8 chapters in teaching case base, which basically cover the teaching of disease genetics and clinical genetics.The construction of teaching case base in medical genetics has realized the deep integration of clinical cases and teaching. Students can understand and master important and difficult points of teaching in a more intuitive way, which is helpful to stimulate students' innovative thinking, improve students' learning interest and class participation.

High-frequency oscillatory activity in cognition-related neural circuits during wakefulness consistently induces the growth of dendritic spines and axonal terminals. Although these structural changes are essential for cognitive functions, it is hypothesized that if these newly expanded structures fail to establish functional connections, they may become superfluous. Sleep is believed to facilitate the reduction of such redundant structures to maintain neural homeostasis. However, the mechanisms underlying this pruning process during sleep remain poorly understood. In this study, that melatonin type 3 receptors (MT3Rs) are selectively expressed in the stellate neurons of the medial entorhinal cortex (MEC) is demonstrated, an area where high melatonin levels are detected during sleep. Activation of MT3Rs during sleep initiates the shrinkage of dendritic spines in stellate neurons by downregulating neural network activity and dephosphorylating synaptic proteins in the MEC. This process is disrupted when MT3R expression is knocked down or when MT3Rs are blocked during sleep. Notably, interference with MT3Rs in the MEC during sleep impairs the acquisition of spatial memory but does not affect object memory acquisition following sleep. These findings reveal novel molecular mechanisms involving melatonin and MT3Rs in the regulation of dendritic spine shrinkage during sleep, which is crucial for the acquisition and consolidation of spatial memory.

Lactate provides signals that modulate neural functions, including excitability, plasticity and memory consolidation. G-protein-coupled receptor 81 (GPR81) is a specific receptor of lactate, which functions in signaling regulation in neural activity. This process is mediated by downstream of GPR81, phosphatidylinositol 3 kinase /protein kinase B/cyclic adenosine monophosphate response element binding protein (PI3K/Akt/CREB) pathway. Previously, it is recognized that lactate content is reduced in the brain of Alzheimer’s disease (AD) model mice. But, it hasn’t been identified whether lactate decrease is related with increased amyloid beta (Aβ) in AD model mice. This work proves that reduced lactate content is correlated with Aβ increase in cortex and hippocampus of AD model mice. Importantly, it signifies that reduced lactate and GPR81 lead to decrease of deoxyribonucleic acid methyltransferase 1 (DNMT1). DNMT1 reduction promotes beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) expression, further increasing Aβ level. Besides, lactate reduction is correlated with decreased expressions of p-PI3K, p-AKT and p-CREB. But, promotion of lactate content activates GPR81-PI3K/Akt/CREB signaling pathway. Hence, it signifies that lactate decrease might contribute to Aβ increase, and underlying mechanism is that reduced lactate induces inhibition of GPR81-PI3K/Akt/CREB pathway, and then decreases DNMT1, increases BACE1 and Aβ levels (Graphic abstract).

Long noncoding RNA (lncRNA) cancer susceptibility 9 (CASC9) has been found to be overexpressed and functions as an oncogene in many cancer types. We investigated the molecular mechanism underlying CASC9 overexpression in esophageal squamous cell carcinoma (ESCC). Transcripts containing exons 2 and 6 and exons 4 and 6 showed the highest CASC9 expression levels in ESCC, no transcripts were detected in the normal esophageal epithelial Het1A cell line. The Long Interspersed Nuclear Element-1 (LINE1 or L1) element in the genome was found to participate in the evolution of lncRNA CASC9, the antisense promoter (ASP) of L1 provides the cis-regulatory elements necessary for CASC9 activation, and the antisense chain of L1 participates in the formation of exons of CASC9. The activation of the antisense promoter was due to the aberrant hypomethylation of L1 elements. An active enhancer element was identified in the downstream region of CASC9 gene by ChIP-seq and ChIP-qPCR. The interaction between ASP and the enhancer elements was confirmed by chromosome conformation capture (3C). Thus, our results suggest that the L1 ASP activation due to aberrant hypomethylation and downstream enhancer interaction plays a key role in the overexpression of lncRNA CASC9 in ESCC.

Abstract Lactate provides signals that modulate neuronal functions, including excitability, plasticity and memory consolidation. This process is mediated by its specific receptor, G-protein-coupled receptor 81 (GPR81), which activates phosphatidylinositol 3 kinase /protein kinase B/cyclic adenosine monophosphate response element binding protein (PI3K/Akt/CREB) signaling pathway. However, it is recognized that cerebral lactate content is reduced at the early stage of Alzheimer’s disease (AD). Besides, continiously production of amyloid beta (Aβ) induces synaptic dysfunction. Here, this study focuses on the decrease of cerebral lactate content, and its relation with Aβ production at early stage of AD. Firstly, it identifies a decrease of lactate level, GPR81 and phosphorylation of PI3K/Akt/CREB, a reduction of deoxyribonucleic acid methyltransferase 1 (DNMT1), an increase of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) and Aβ in the cortex and hippocampus of early AD model mice. Then, through correlation analysis, it is found that reduction of cerebral lactate level is positively correlative with the decreased phosphorylation of PI3K/Akt/CREB. Especially, phosphorylation of CREB is positively correlative with DNMT1 expression, and negatively correlated with BACE1 and Aβ level. These results signify that reduction of cerebral lactate content contributes to suppression of PI3K/Akt/CREB signaling pathway, leading to DNMT1 downregulation. As a result, BACE1 and Aβ are increased in the cortex and hippocampus of early AD model mice. Hence, this study proposes a novel insight that lactate reduction contributes to Aβ production at early period of AD. The underlying mechanism is that reduced lactate can hardly activate GPR81-PI3K/Akt/CREB, which results in DNMT1 reduction, and then increasing BACE1 level and Aβ production (Graphic Abstract).

Abstract Lactate arouses an increasing concern in recent studies of Alzheimer’s disease (AD). At late stage of AD, amyloid beta (Aβ) directly promotes lactate level, continuously activating microglial inflammation and aggravating neuronal damage. However, whether lactate fluctuation can effect on Aβ hasn’t been recognized. Especially, it is observed a reduction of lactate in the hippocampus and cortex of early AD mouse model. Hence, this study discusses the relation between decreased lactate and Aβ production at early stage of AD, and its possibly mechanism. As results showed, a specific receptor of lactate, G-protein-coupled receptor 81 (GPR81) and its downstream of phosphatidylinositol 3 kinase /protein kinase B (PI3K/Akt)-cyclic-adenosine-monophosphate response element-binding protein (CREB) is suppressed in the cortex and hippocampus of early AD mouse model. Moreover, deoxyribonucleic acid methyltransferase 1 (DNMT1) is reduced in the presence of increased beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) and Aβ. Previously, it is observed that PI3K/Akt-CREB inhibition leads to DNMT1 downregulation. As an indispensable methyltransferase, DNMT1 reduction can directly inhibit the methylation of specific loci within BACE1 gene promoter, leading to increased BACE1 and Aβ production. Hence, this study proposes a novel insight that lactate reduction contributes to Aβ production at early period of AD. The underlying mechanism is that reduced lactate can hardly activate GPR81-PI3K/Akt-CREB, which results in DNMT1 reduction, and then increasing BACE1 level and Aβ production (Graphic abstract).

Lactate is not only an energy metabolite for neurons, but also serves as a molecule regulator affecting neuronal activity through its receptor, G protein-coupled receptor 81 (GPR81). This receptor can trigger cellular signaling pathways, such as phosphatidylinositol 3 kinase /protein kinase B (PI3K/Akt) pathway. Particularly, lactate deficit and inhibition of PI3K/Akt pathway were observed to be related with early synaptic dysfunction in Alzheimer’s disease (AD). In addition, amyloid beta (Aβ) is toxic to neurons, while in vitro lactate administration of neurons can resist against this toxicity. Hence, this work focuses on the effect of lactate deficiency on Aβ production, suggesting that lactate decrease can inhibit GPR81-PI3K/Akt pathway, and then reduce deoxyribonucleic acid methyltransferase 1 (DNMT1) expression, further resulting in increase of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) and Aβ production. Based on the analysis of results, this study primarily proves that lactate reduction suppresses its downstream GPR81-PI3K/Akt pathway, which decreases the expression of DNMT1 through regulating cyclic-adenosine-monophosphate response element-binding protein (CREB)/P300. Then, it is proved that DNMT1 reduction can lead to the increase of BACE1 and Aβ accumulation in AD. At last, in vitro experiment recognizes that lactate directly activates GPR81-PI3K/Akt pathway. Thus, this study provides a novel insight in Aβ production in relation with lactate deficit at early stage of AD. Particularly, it is suggested that extra addition of lactate might be protective for neurons targeting Aβ clearance in early treatment of AD.

SCOPE:Choline is an essential nutrient and a primary dietary source of methyl groups that are vital for brain development. Low choline (LC) in the maternal diet during pregnancy alters neurogenesis in the fetal brain and leads to low cognitive performance. However, the key signaling pathways that are sensitive to maternal choline supply during neural progenitor cell (NPC) development and the epigenetic mechanisms by which choline availability regulates gene expression are unclear.METHODS AND RESULTS:Timed-pregnant Nestin-CFPnuc transgenic mice are fed either a control diet or LC diet during E11-17. Gene expression changes in sorted E17 NPCs are identified by RNA sequencing. A maternal LC diet significantly increases Tlr4 transcription, causing premature neuronal differentiation and enhanced ethanol-induced NLRP3 inflammasome activation. No changes in DNA methylation at the Tlr4 gene promoter region are detected; however, a 70% decrease in H3K27me3 is observed in the LC-treated NPCs. Inhibition of EZH2 decreases H3K27me3 levels and increases Tlr4 expression. Conversely, the application of catalytically inactive Cas9 with EZH2 to increase H3K27me3 at the Tlr4 promoter causes reduced Tlr4 expression.CONCLUSION:These data reveal an epigenetic mechanism for the effect of maternal choline availability on brain development, suggesting a likely intervention for neurodevelopmental diseases.

Angelicin is an active compound isolated from the Chinese herb Angelica archangelica, which has been reported to exert antitumor effects by inhibiting malignant behaviors in several types of tumor, including proliferation, colony formation, migration and invasion. However, the effects of angelicin on human cervical cancer cells is yet to be elucidated. The present study evaluated the antitumor effects of angelicin on cervical cancer cells. The results demonstrated that cervical cancer cells were more sensitive to angelicin than cervical epithelial cells. At its IC30, angelicin inhibited the proliferation of HeLa and SiHa cells by blocking the cell cycle at the G1/G0 phase and inhibiting other malignant behaviors, including colony formation, tumor formation in soft agar, migration and invasion. At the IC50, angelicin induced cell death potentially by promoting apoptosis. By identifying the hallmarks of autophagy, it was observed that angelicin treatment caused the accumulation of microtubule associated protein 1 light chain 3-β (LC3B) in the cytoplasm of HeLa and SiHa cells. Western blotting results demonstrated that cleaved LC3B-II and autophagy related proteins (Atg)3, Atg7 and Atg12-5 were upregulated following angelicin treatment. It was also determined that the phosphorylation of mTOR was induced by angelicin treatment. Furthermore, the inhibition of angelicin-induced mTOR phosphorylation did not disrupt its inhibitory effect on autophagy, indicating that angelicin inhibited autophagy in an mTOR-independent manner. Taken together, the present results suggested that angelicin regulated malignant behaviors in cervical cancer cells by inhibiting autophagy in an mTOR-independent manner. Findings suggested that autophagy might be a potential therapeutic target for cervical cancer.

An increasing number of long noncoding RNAs (lncRNAs) have been discovered, and dysregulation of lncRNAs plays critical roles in tumorigenesis and tumor progression. In this study, we identified a novel lncRNA LINC01980, located in both the cytoplasm and nucleus, which was significantly upregulated in esophageal squamous cell carcinoma (ESCC) tissues through microarray profiling. Further analysis revealed that LINC01980 overexpression was positively correlated with deeper invasion of cancer, positive lymph node metastasis, and advanced TNM stage. Additionally, high LINC01980 expression in ESCC tissues was associated with poor prognosis. In vitro and in vivo experiments demonstrated that LINC01980 promoted ESCC growth. EdU incorporation assay implied that LINC01980 accelerated ESCC proliferation. Flow cytometry analysis showed that knockdown of LINC01980 induced cell cycle arrest and increased apoptosis. Microarray analysis indicated that LINC01980 upregulated the expression of growth arrest and DNA damage inducible 45 alpha (GADD45A). Further experiments demonstrated that GADD45A promoted ESCC cell growth, indicating that GADD45A may be a downstream target of LINC01980. In conclusion, this study identified LINC01980 as a novel potential oncogene in ESCC, which can be a promising biomarker for prognosis and therapeutic targeting in ESCC.

ScopeAlzheimer's disease (AD) is a detrimental neurodegenerative disease and has no known effective treatment. The essential nutrient choline potentially plays an important role in cognition. Perinatal choline supplementation (CS) is critical for memory performance. Findings have shown that postnatal choline‐containing compounds enhance memory functions in populations with memory impairments. However, whether CS can be targeted to decelerate the progression of AD remains unknown.Methods and resultsAPP/PS1 mice and their wild‐type littermates are fed either a control or CS diet from 2 to 11 months of age. As compared to WT mice, APP/PS1 mice on the control diet are characterized by the reduction in the number of cholinergic neurons in the basal forebrain, reduced cholinergic fiber staining intensity in the amygdala, and reduced hippocampal and cerebral cortical levels of choline and acetylcholine. CS partially prevents these changes and ameliorates cognitive deficits and anxiety. Furthermore, amyloid‐β deposition and microgliosis are decreased in the APP/PS1 mice fed a CS diet. These effects may have been due to inhibition of NLRP3 inflammasome activation and restoration of synapse membrane formation.ConclusionThese findings reveal a beneficial effect of CS on AD progression during adulthood and provide a likely therapeutic intervention for AD patients.

Esophageal squamous cell carcinoma (ESCC) is the main subtype of esophageal cancer. Long noncoding RNAs (lncRNAs) are thought to play a critical role in cancer development. Recently, lncRNA CASC9 was shown to be dysregulated in many cancer types, but the mechanisms whereby this occurs remain largely unknown. In this study, we found that CASC9 was significantly upregulated in ESCC tissues, with further analysis revealing that elevated CASC9 expression was associated with ESCC prognosis and metastasis. Furthermore, we found that CASC9 knockdown significantly repressed ESCC migration and invasion in vitro and metastasis in nude mice in vivo. A microarray analysis and mechanical experiments indicated that CASC9 preferentially affected gene expression linked to ECM–integrin interactions, including LAMC2, an upstream inducer of the integrin pathway. We demonstrated that LAMC2 was consistently upregulated in ESCC and promoted ESCC metastasis. LAMC2 overexpression partially compromised the decrease of cell migration and invasion capacity in CASC9 knockdowns. In addition, we found that both CASC9 and LAMC2 depletion reduced the phosphorylation of FAK, PI3K, and Akt, which are downstream effectors of the integrin pathway. Moreover, the reduction in phosphorylation caused by CASC9 depletion was rescued by LAMC2 overexpression, further confirming that CASC9 exerts a pro-metastatic role through LAMC2. Mechanistically, RNA pull-down and RNA-binding protein immunoprecipitation (RIP) assay indicated that CASC9 could bind with the transcriptional coactivator CREB-binding protein (CBP) in the nucleus. Chromatin immunoprecipitation (ChIP) assay additionally illustrated that CASC9 increased the enrichment of CBP and H3K27 acetylation in the LAMC2 promoter, thereby upregulating LAMC2 expression. In conclusion, we demonstrate that CASC9 upregulates LAMC2 expression by binding with CBP and modifying histone acetylation. Our research reveals the prognostic and pro-metastatic roles for CASC9 in ESCC, suggesting that CASC9 could serve as a biomarker for prognosis and a target for metastasis treatment.

Background SOX2 overlapping transcript (SOX2OT) has been reported to be an important lncRNA in various cancers. SOX2 is embedded in an intron of the SOX2OT gene. But the role of SOX2OT in esophageal squamous cell carcinoma (ESCC) and the association between SOX2OT and SOX2 remain unclear. Methods Quantitative PCR (qPCR) was used to detect the expression of SOX2OT and SOX2 in ESCC tissues and cells. The isoforms of SOX2OT were identified by PCR and confirmed by sequencing. CCK-8 and Edu assays were performed to investigate the effects of SOX2OT on cell growth. The relationship between SOX2OT and SOX2 was explored by luciferase reporter assay. Results Both SOX2OT and SOX2 were upregulated in ESCC tissues and cells. SOX2OT expression was positively associated with SOX2 expression in ESCC tissues. NR_004053 was one of the major SOX2OT transcripts aberrantly expressed in ESCC tissues and cells. Overexpression of SOX2OT (NR_004053) promoted ESCC cell growth, antagonized the effect of DDP and increased cell proliferation ratio. Ectopic expression of SOX2 could increase the luciferase activity of SOX2OT-pGL3/Basic and SOX2OT expression, while overexpression of SOX2OT (NR_004053) had no effect on SOX2 expression. Conclusion Our study demonstrates that the major isoform of SOX2OT in ESCC, SOX2OT (NR_004053) contributes to cell growth. SOX2 promotes SOX2OT expression at transcriptional level.

Epidemiological studies have revealed the association between increased risk of bladder cancer and chronic arsenic exposure. Here, we explored biological effects of arsenic in T24. Microarray analysis was applied to analyze mRNA in T24 following 0, 2 or 5 μM sodium arsenite (As) exposure for 72 hours. Long term (up to 140 days) low-dose (200 nM) and high-dose (1,000 nM) As decreased E-cadherin protein level through different mechanisms because the mRNA levels of E-cadherin increased following low-dose As exposure but decreased following high-dose As exposure. Long term As increased the protein levels of N-cadherin, vimentin, β-catenin, and slug. Low-dose As exposure resulted in a change in the morphology of T24 cells from an epithelial to a mesenchymal-like appearance. Knockdown of E-cadherin increased the protein levels of N-cadherin, vimentin, β-catenin, and slug. Cell proliferation and growth of T24 with or without As exposure for 100 days were assayed using EdU and WST, respectively. Low-dose As exposure increased cell proliferation and growth while high-dose As exposure decreased both. Long term As activated p53 on account of increasing protein levels of p53, p-p53 (Ser15), and mRNA levels of p21. These demonstrate that arsenic exposure exerts multiple effects. Long term low- or high-dose arsenic induces epithelial-mesenchymal transition, likely via downregulation of E-cadherin, activates p53, and differently affects cell proliferation/growth.

Dysregulation of c-Myc is one of the most common abnormalities in human malignancies, including esophageal cancer, one of the world's most lethal cancers. MicroRNA-26 family, including miR-26a and miR-26b, is transcriptionally suppressed by c-MYC. Our previous microarray data indicated a decreased-expression of miR26 family in esophageal squamous cell carcinoma (ESCC). However, its roles in c-MYC pathway regulation and esophageal cancer tumorigenesis have yet not been elucidated. In this study, we expanded the detection of miR26 expression in ESCC patients and found that the great majority of ESCC tissues showed an > 50% reduction, even in the early-staged tumor. Furthermore, ectopic expression of miR-26a or miR-26b induced ESCC cell growth inhibition and G1 phase arrest. MYC binding protein (MYCBP) was identified as a direct target of miR-26. MiR-26 could dramatically decrease MYCBP mRNA and protein levels, as well as the expression of luciferase carrying MYCBP 3'-untranslated region. Moreover, knock-down of MYCBP mimicked the effect of miR-26. More importantly, miR-26 overexpression could downregulate a series of c-MYC target genes as MYCBP silence did. Taken together, these results indicate that miR-26 family can suppress esophageal cancer cell proliferation by inhibition of MYCBP, subsequently downregulate c-MYC pathway. Besides, we also found that reduction of miR26 expression in ESCC was not due to DNA methylation. Hence, our study reveals a novel feedback loop for cMYC pathway and implicates miR-26 as a potential target for prevention and treatment of esophageal cancer.

BACKGROUND:Abnormal expression of numerous long non-coding RNAs (lncRNAs) has been reported in esophageal squamous cell carcinoma (ESCC) recently, but the great majority of their roles and mechanisms remain largely unclear. We aim to identify the critical ESCC-associated lncRNAs and elucidate the functions and mechanisms in detail.METHODS:Microarrays were used to analyze the differentially expressed lncRNAs in ESCC tissues. qRT-PCR was used to verify the result of microarrays. The effects of the most up-regulated lncRNA, cancer susceptibility candidate 9(CASC9), on cell growth, proliferation and cell cycle were investigated by in vivo and in vitro assays. Microarrays and recovery tests were used to discover the regulatory targets of CASC9. RNA FISH and subcellular fractionation assays were used to detect the subcellular location of CASC9. Finally, the mechanism of CASC9 regulating PDCD4 was explored by RIP, RNA-protein pull down and ChIP assays.RESULTS:ESCC tissue microarrays showed that CASC9 was the most up-regulated lncRNA. qRT-PCR analysis indicated that CASC9 expression was positively associated with tumor size and TNM stage, and predicted poor overall survival of ESCC patients. Knockdown of CASC9 inhibited ESCC cell growth in vitro and tumorigenesis in nude mice. Furthermore interfering CASC9 decreased cell proliferation and blocked cell cycle G1/S transition. CASC9-associated microarrays indicated that PDCD4 might be the target of CASC9. Consistent with this, PDCD4 expression was negatively associated with CASC9 expression in ESCC tissues and predicted good prognosis. Manipulating CASC9 expression in ESCC cells altered both PDCD4 mRNA and protein levels and cell cycle arrest caused by CASC9 knockdown could be rescued by suppressing PDCD4 expression. CASC9 located both in the nucleus and cytoplasm. Mechanistically, enhancer of zeste homolog2 (EZH2) could bind to both CASC9 and PDCD4 promoter region. Interfering CASC9 reduced the enrichment of EZH2 and H3K27me3 in the PDCD4 promoter region.CONCLUSIONS:Our study firstly demonstrates that lncRNA CASC9 functions as an oncogene by negatively regulating PDCD4 expression through recruiting EZH2 and subsequently altering H3K27me3 level. Our study implicates lncRNA CASC9 as a valuable biomarker for ESCC diagnosis and prognosis.

Esophageal cancer is one of the leading causes of cancer-related mortality because of poor prognosis. Long noncoding RNAs (lncRNAs) have been gradually demonstrated to play critical roles in cancer development. We identified a novel long noncoding RNA named linc00460 by microarray analysis using esophageal squamous cell carcinoma (ESCC) clinical samples, which has not been studied before. Our research indicated that linc00460 was overexpressed in the majority of tumor tissues and ESCC cell lines. Linc00460 expression was positively correlated with ESCC TNM stage, lymph node metastasis, and predicted poor prognosis. In vitro experiments showed that linc00460 depletion suppressed ESCC cell growth through regulating cell proliferation and cell cycle; in additional, linc00460 depletion accelerated ESCC cell apoptosis. We further revealed that linc00460 overexpression was manipulated by transcriptional co-activator CBP/P300 through histone acetylation. Given the high expression and important biological functions of linc00460, we suggest that linc00460 works as an oncogene and might be a valuable prognostic biomarker for ESCC diagnosis and treatment.

Three-dimensional (3D) culture models represent a better approximation of solid tumor tissue architecture, especially cell adhesion, in vivo than two-dimensional (2D) cultures do. Here, we explored the role of architecture in chemosensitivity to platinum in colon cancer. Under the 3D culture condition, colon cancer cells formed multicellular spheroids, consisting of layers of cells. 3D cultures displayed significantly decreased sensitivity to platinum compared with 2D cultures. Platinum increased p53 in a dose-dependent and time-dependent manner. There was no detectable difference in basal p53 levels between 3D cultures and 2D cultures but cisplatin induced less p53 in both HCT116 3D cultures and LoVo 3D cultures. It was not due to cisplatin concentration because cisplatin induced similar γ-H2AX in 3D vs 2D. Knockdown of p53 significantly decreased sensitivity to platinum in 3D cultures. Knockdown of p53 decreased cleaved caspase 3 and apoptosis induced by cisplatin. These findings indicate that 3D architecture confers decreased chemosensitivity to platinum and p53 is involved in the mechanism. Knockdown of p53 decreased cisplatin's induction of c-Jun N-terminal kinase 1/2 (JNK1/2) activation, whereas inhibition of JNK1/2 activation increased chemosensitivity. Inhibition of p38 activation decreased cisplatin's induction of p53, but no difference in p38 activation by cisplatin was observed between 2D cultures and 3D cultures. Taken together, our results suggest that p53 is involved in a 3D architecture-mediated decrease in chemosensitivity to platinum in colon cancer. Mitogen-activated protein kinases (JNK1/2 and p38) do not play a dominant role in the mechanism.

Objective: The human T cell transcription factor-4 (TCF4) interacts functionally with β-catenin in the Wnt signaling pathway, whose deregulation is involved in the tumorigenesis of various types of cancers. Recent studies showed that TCF4 mRNAs were subject to alternative splicing, which was proposed to be important in regulating transactivational properties of the corresponding protein isoforms. Here we investigated the splicing isoforms and the roles of TCF4 in human esophageal squamous cell carcinoma. Methods: RT-PCR and subsequent cloning and sequencing were applied to identify the splicing isoforms. Western blotting and realtime PCR were used to analyze the expression of TCF4. Knockdown of TCF4 was achieved with siRNA and stable transfection of expression vectors was performed. Results: Our results showed there were a lot of different isoforms of TCF4 mRNA both in human esophageal cancers and cell line. Further, knockdown of TCF4E isoform expression in EC109 cells inhibited the cell growth, while overexpression of TCF4M isoform did not alter its transcription activity. Moreover, sixteen potential binding proteins of TCF4 were preliminarily identified by mass spectrometry. Conclusions: Our data suggested that deregulation of TCF4 isoforms may contribute to the tumorigenesis of ESCC.