Exogenous expression of Esophagin/SPRR3 attenuates the tumorigenicity of esophageal squamous cell carcinoma cellsviapromoting apoptosis

A tumor cornification and immune-infiltration-based scheme for anti-PD-1 plus chemotherapy response in advanced squamous cell lung carcinoma

BACKGROUND

Anti-PD-1 immunotherapy plus chemotherapy (combo) exhibits significantly prolonged survival for squamous cell lung cancer (LUSC). An exploration of predictive biomarkers is still needed.

METHODS

High-throughput RNA sequencing (RNA-seq) of 349 LUSC samples from the randomized, multi-center, phase 3 trial ORIENT-12 (ClinicalTrials.gov: NCT03629925) was conducted for biomarker discovery, followed by flow cytometry and multiplex immunohistochemistry (mIHC) in additional clinical cohorts, and in vitro experiments were performed for verification.

RESULTS

A high abundance of activated CD8+ T and CD56bright natural killer (NK) cells benefited patients' outcomes (progression-free survival [PFS]; overall survival [OS]) with combo treatment. Tumor cornification level remarkably affected the infiltration of the two crucial immune cells. Thus, a novel scheme of LUSC immune infiltration and cornification characterization-based classification (LICC) was established for combo efficacy prediction. Patients who received combo treatment achieved significant PFS improvements in LICC1 (hazard ratio [HR] = 0.43, 95% confidence interval [CI]: 0.25-0.75, p = 0.0029) and LICC2 (HR = 0.32, 95% CI: 0.17-0.58, p = 0.0002) subtypes but not in the LICC3 subtype (HR = 0.86, 95% CI: 0.60-1.23, p = 0.4053). Via single-cell RNA-seq analysis, the tumor cornification signal was mainly mapped to SPRR3+ tumor cells, whose relationships with activated CD8+ T or CD56bright NK cells were verified using flow cytometry and mIHC. Our data suggest that SPRR3+ tumor cells might evade immune surveillance via the CD24-SIGLEC10 (M2 macrophage) axis to maintain a suppressive tumor microenvironment.

CONCLUSIONS

Tumor cornification greatly impacts immune infiltration, and the LICC scheme may guide clinical medication of anti-PD-1+chemo treatment in patients with LUSC.

FUNDING

The study was funded by the National Key R&D Program of China, the National Natural Science Foundation of China, Shanghia Multidisplinary Cooperation Building Project for Diagnosis and Treatment of Major Disease, and Innovent Biologics, Inc.

Predictive role and molecular biological function of proline-rich small repeat protein SPRR3 in the diagnosis of lung adenocarcinoma

The fascinating role of SPRR3 in various malignant tumors has prompted extensive research to unravel its expression patterns and prognostic significance. To comprehensively investigate SPRR3, we leveraged multiple datasets containing invaluable biomedical information, specifically focusing on the comparative analysis of SPRR3 gene expression levels across different cancer types. Meticulous examination of lung adenocarcinoma allowed us to delve deeper into the correlation between SPRR3 expression and its molecular biological functions. Our comprehensive analysis encompassed 33 malignant tumors, and the results unveiled significant differential expression of SPRR3 across a range of malignancies. Moreover, this aberrant expression of SPRR3 was observed to be closely associated with poorer prognosis in these malignant tumors. Notably, our investigation also unearthed a compelling link between SPRR3 and immune infiltrating cells in lung adenocarcinoma. The utilization of receiver operating characteristic (ROC) curves and survival curves in our study illustrated the immense potential of SPRR3 as a highly accurate predictor of cancer. These findings further emphasize the possibility of SPRR3 serving as a promising diagnostic and prognostic biomarker for a diverse array of cancers.

SPRR3 Contributes to Aggressiveness of Pancreatic Cancer Cells via NF-κB Signaling Pathway

Pancreatic cancer remains a deadly solid tumor with worst survival, and a better understanding of the mechanisms of carcinogenesis of pancreatic cancer is critical to promote the survival of patients with pancreatic cancer. qPCR and western blot assay were used to determine the expression of SPRR3 in pancreatic cancer. Anchorage-independent growth ability, BrdU labeling, Transwell assay, and in vivo experiment were used to examine the functions of SPRR3 in aggressiveness of pancreatic cancer. Luciferase reporter assay, nucleoplasmic-separation technique, qPCR, and western blot assay were used to investigate the mechanism of SPRR3 regulating aggressiveness of pancreatic cancer. Our results showed that SPRR3 was significantly increased in pancreatic cancer, which resulted in poor survival for patients with pancreatic cancer. Further analysis showed that overexpression of SPRR3 contributed to anchorage-independent growth ability, growth rate, and invasion ability of pancreatic cancer cells. While, knockdown of SPRR3 showed the reverse results. Mechanistically, overexpression of SPRR3 can promote the transcription of NF-κB pathway, nuclear accumulation of p65, and mRNA levels of NF-κB pathway downstream genes. But, knockdown of SPRR3 induced the reverse results. The above findings clarified the important roles of SPRR3 in the progression of pancreatic cancer through NF-κB pathway. And targeting SPRR3 might be an effective strategy to therapy pancreatic cancer.

SPRR3, a novel miR‑338‑3p target, regulates the malignant progression of clear cell renal cell carcinoma in vitro via the PI3K/Akt signaling pathway

Clear cell renal cell carcinoma (ccRCC) is the most common type of renal cell carcinoma and has a poor prognosis. However, its underlying mechanisms remain unclear. The present study aimed to evaluate the role of small proline-rich repeat protein 3 (SPRR3) in the proliferation, migration and invasion of ccRCC cells and to investigate its upstream and downstream regulatory mechanisms. Survival analysis was performed using the UALCAN website based on the The Cancer Genome Atlas database. Normal renal cell line HK-2 and ccRCC cell lines (786-O, CaKi-1 and UMRC-2) were used. Reverse transcription-quantitative PCR (RT-qPCR) was used to detect mRNA and microRNA (miRNA) levels. Western blotting was used to detect protein levels. Cell Counting Kit-8 and colony formation assays, a wound healing assay and a Transwell invasion assay were used to assess the proliferation, migration and invasion of ccRCC cells, respectively. Transfection of overexpression plasmids and small interfering RNAs were used to upregulate and knockdown SPRR3 expression, respectively. Transfection of miRNA-mimics was used to overexpress miR-338-3p. A luciferase reporter gene assay was used to verify the predicted binding relationship between SPRR3 mRNA and miR-338-3p. The results indicated the following: i) SPRR3 was a risk factor for the survival of patients with ccRCC, and was upregulated in ccRCC cell lines; ii) SPRR3 promoted the proliferation, migration and invasion of ccRCC cells; iii) SPRR3 regulated the tumor phenotypes of ccRCC cells via the PI3K/Akt pathway; iv) miR-338-3p directly targeted SPRR3 mRNA and negatively regulated SPRR3 expression; and v) miR-338-3p inhibited the PI3K/Akt pathway and the tumor phenotypes of ccRCC cells by downregulating SPRR3. In conclusion, SPRR3, as a novel target of miR-338-3p, regulated the proliferation, migration and invasion of ccRCC cells via the PI3K/Akt pathway; this finding not only enriches our understanding of the mechanism underlying ccRCC development, but also demonstrates a potential novel therapeutic target for this disease.

DNAJB8 in small extracellular vesicles promotes Oxaliplatin resistance through TP53/MDR1 pathway in colon cancer

Chemotherapy is one of the most frequently used therapies for the treatment of colon cancer (COAD). However, Oxaliplatin (L-OHP) resistance is a major obstacle to the effective treatment of COAD. Here, we investigated whether DNAJB8, a heat shock protein 40 (HSP40) family protein, could be used for the prognosis and therapy of L-OHP resistance in COAD. Treatment with small interfering RNA targeting DNAJB8 could restore the response to L-OHP in vitro and in vivo. On the mechanism, we demonstrated that DNAJB8 could interact with TP53 and inhibit the ubiquitination degradation of TP53, leading to MDR1 upregulation which promotes colon cancer L-OHP resistance. We found that small extracellular vesicle (sEV)-mediated transfer of DNAJB8 from L-OHP-resistant COAD cells to sensitive cells contributed to L-OHP resistance. A prognostic signature based on the DNAJB8 levels in both tissue and serum showed that COAD patients with high-risk scores exhibited significantly worse overall survival and disease-free survival than patients with low-risk scores. These results indicate that DNAJB8 levels in serum sEVs may serve as a biomarker for COAD. DNAJB8 from sEVs might be a promising therapeutic target for L-OHP resistance and a prognostic predictor of clinical response.

Molecular Pathways Associated with Kallikrein 6 Overexpression in Colorectal Cancer

Colorectal cancer (CRC) remains one of the leading causes of cancer-related death worldwide. The high mortality of CRC is related to its ability to metastasize to distant organs. The kallikrein-related peptidase Kallikrein 6 (KLK6) is overexpressed in CRC and contributes to cancer cell invasion and metastasis. The goal of this study was to identify KLK6-associated markers for the CRC prognosis and treatment. Tumor Samples from the CRC patients with significantly elevated KLK6 transcript levels were identified in the RNA-Seq data from Cancer Genome Atlas (TCGA) and their expression profiles were evaluated using Gene Ontology (GO), Phenotype and Reactome enrichment, and protein interaction methods. KLK6-high cases had a distinct spectrum of mutations in titin (TTN), APC, K-RAS, and MUC16 genes. Differentially expressed genes (DEGs) found in the KLK6-overexpressing CRCs were associated with cell signaling, extracellular matrix organization, and cell communication regulatory pathways. The top KLK6-interaction partners were found to be the members of kallikrein family (KLK7, KLK8, KLK10), extracellular matrix associated proteins (keratins, integrins, small proline rich repeat, S100A families) and TGF-β, FOS, and Ser/Thr protein kinase signaling pathways. Expression of selected KLK6-associated genes was validated in a subset of paired normal and tumor CRC patient-derived organoid cultures. The performed analyses identified KLK6 itself and a set of genes, which are co-expressed with KLK6, as potential clinical biomarkers for the management of the CRC disease.

Differentiation-related zinc finger protein 750 suppresses cell growth in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a deadly squamous cell carcinoma (SCC) of the esophagus. Development of SCCs is associated with the deregulation of the squamous cell lineage program and/or keratinocyte terminal differentiation by genomic and genetic aberrations; thus, these processes must be tightly controlled to maintain normal squamous cell development. Zinc finger protein 750 (ZNF750) is a gene involved in keratinocyte terminal differentiation and is frequently mutated and putatively silenced in ESCC, which implicates its function as a potential differentiation-related suppressor of ESCC. The present study aimed to elucidate the relationship between ZNF750 function to induce keratinocyte differentiation and tumor suppression in ESCC. The results demonstrated that chemical manipulation of esophageal keratinocyte differentiation in mouse normal esophageal epithelial organoids (mNEEO) implicated the involvement of the mouse homologue of ZNF750, Zfp750, in keratinocyte differentiation in premalignant cells. Bioinformatics analyses of data from high ZNF750-expressing ESCC tumors obtained from public databases and ZNF750-overexpressing ESCC cells compared with low ZNF750-expressing ESCC tumors and GFP-expressing ESCC cells, respectively, revealed enrichment of keratinocyte differentiation-related gene sets in these samples. Finally, the induction through to terminal differentiation of the keratinocyte by all-trans retinoic acid on parental ESCC cell lines led to the upregulation of the terminal differentiation marker Involucrin and a decrease in cell viability similar to that observed in ZNF750-overexpressing ESCC cells. The results of the present study demonstrated a functional link between the ability of ZNF750 to induce cell differentiation through to terminal differentiation and its function as a growth suppressor in ESCC. This study provides improved understanding of the role of ZNF750, a frequently mutated differentiation-related gene in ESCC, and its effects in ESCC pathogenesis.

Identification of crucial long non-coding RNAs and mRNAs along with related regulatory networks through microarray analysis in esophageal carcinoma

Esophageal carcinoma (EC) is a tremendous threat to human health and life worldwide. Long non-coding RNAs (lncRNAs) have been identified as crucial players in carcinomas including EC. An in-depth understanding on regulatory networks of lncRNAs contributes to the better management of EC. In this text, 2052 lncRNAs and 3240 mRNAs were found to be differentially expressed in 5 EC tumor tissues versus adjacent normal tissues by microarray analysis. Moreover, 297 carcinoma-related genes were screened out according to pathway and disease annotation analyses. In addition, 410 potential lncRNA-mRNA cis-regulation pairs and 395 lncRNA-mRNA trans-regulation pairs were screened out. Among these genes, 14 trans-regulated and 19 cis-regulated genes were found to be related with carcinomas. Additionally, 42 possible lncRNA-mRNA trans-regulation pairs and 26 cis-regulation pairs were found to be related with carcinomas. Also, 4 differentially expressed transcription factors in EC and lncRNAs possibly regulated by these transcription factors were screened out. Moreover, plenty of common upregulated or downregulated lncRNAs and mRNAs in EC were identified by comparative analysis for our microarray outcomes and previous high-throughput data. Furthermore, we demonstrated that ENST00000437781.1 knockdown inhibited cell proliferation and facilitated cell apoptosis by downregulating SIX homeobox 4 (SIX4) and ENST00000524987.1 knockdown had no influence on anoctamin 1 calcium activated chloride channel (ANO1) expression in EC cells. In conclusion, we identified some crucial lncRNAs and genes along with potential regulatory networks of lncRNAs/genes, deepening our understanding on pathogenesis of EC.

DNA Methylome Distinguishes Head and Neck Cancer from Potentially Malignant Oral Lesions and Healthy Oral Mucosa

There is a strong need to find new, good biomarkers of head and neck squamous cell carcinoma (HNSCC) because of the bad prognoses and high mortality rates. The aim of this study was to identify the potential biomarkers in HNSCC that have differences in their DNA methylome and potentially premalignant oral lesions, in comparison to healthy oral mucosa. In this study, 32 oral samples were tested: nine healthy oral mucosae, 13 HNSCC, and 10 oral lesions for DNA methylation by the Infinium MethylationEPIC BeadChip. Our findings showed that a panel of genes significantly hypermethylated in their promoters or specific sites in HNSCC samples in comparison to healthy oral samples, which are mainly oncogenes, receptor, and transcription factor genes, or genes included in cell cycle, transformation, apoptosis, and autophagy. A group of hypomethylated genes in HNSCC, in comparison to healthy oral mucosa, are mainly involved in the host immune response and transcriptional regulation. The results also showed significant differences in gene methylation between HNSCC and potentially premalignant oral lesions, as well as differently methylated genes that discriminate between oral lesions and healthy mucosa. The given methylation panels point to novel potential biomarkers for early diagnostics of HNSCC, as well as potentially premalignant oral lesions.

Retinoic acid receptor γ activation promotes differentiation of human induced pluripotent stem cells into esophageal epithelium

BACKGROUND

The esophagus is known to be derived from the foregut. However, the mechanisms regulating this process remain unclear. In particular, the details of the human esophagus itself have been poorly researched. In this decade, studies using human induced pluripotent stem cells (hiPSCs) have proven powerful tools for clarifying the developmental biology of various human organs. Several studies using hiPSCs have demonstrated that retinoic acid (RA) signaling promotes the differentiation of foregut into tissues such as lung and pancreas. However, the effect of RA signaling on the differentiation of foregut into esophagus remains unclear.

METHODS

We established a novel stepwise protocol with transwell culture and an air-liquid interface system for esophageal epithelial cell (EEC) differentiation from hiPSCs. We then evaluated the effect of all-trans retinoic acid (ATRA), which is a retinoic acid receptor (RAR)α, RARβ and RARγ agonist, on the differentiation from the hiPSC-derived foregut. Finally, to identify which RAR subtype was involved in the differentiation, we used synthetic agonists and antagonists of RARα and RARγ, which are known to be expressed in esophagus.

RESULTS

We successfully generated stratified layers of cells expressing EEC marker genes that were positive for lugol staining. The enhancing effect of ATRA on EEC differentiation was clearly demonstrated with quantitative reverse transcription polymerase chain reaction, immunohistology, lugol-staining and RNA sequencing analyses. RARγ agonist and antagonist enhanced and suppressed EEC differentiation, respectively. RARα agonist had no effect on the differentiation.

CONCLUSION

We revealed that RARγ activation promotes the differentiation of hiPSCs-derived foregut into EECs.

Cellular heterogeneity landscape in laryngeal squamous cell carcinoma

Laryngeal squamous cell carcinoma (LSCC) is a highly malignant tumor originated from respiratory system. Although there have been many improvements in therapy until now, reducing the high mortality remains difficult. Understanding the cellular heterogeneity of LSCC could contribute to improve this problem. Single-cell RNA sequencing was applied to dissect the cell composition and molecular characteristics of LSCC tissues. Immunohistochemistry staining of the LSCC tissues was performed to identify the spatial location of tumor cells. Survival analysis of marker genes was executed in The Cancer Genome Atlas to verify the correlation between each cell clusters and patients' prognosis. The LSCC tissue cells were finely grouped into various clusters, including tumor cells, immune cells, epithelial cells, fibroblasts and endothelial cells. Notably, in tumor cells, keratinocyte-like cells were in the core of tumor while malignant proliferating cells were located at the tumor edge. The malignant proliferating cells were correlated with poor prognosis. In summary, this is the first study to delineate a landscape of the LSCC intratumor heterogeneity. Our work might help researchers have a better understanding for tumor progression.

Dysregulation of SPRR3/miR-876-3p Axis Contributes to Tumorigenesis in Non-Small-Cell Lung Cancer

Background

SPRR3, also known as esophagin, has been shown to be involved in the initiation and progression of numerous types of tumor. However, the biological function of SPRR3 that contributes to non-small-cell lung cancer (NSCLC) growth and migration is largely unknown.

Methods

The expression of SPRR3 and its association with EZH2 and miR-876-3p in NSCLC cells were determined by real-time PCR. Protein levels were measured by immunohistochemistry (IHC) and Western blot. Cell functions were studied by CCK-8, transwell assay, flow cytometry and dual-luciferase reporter assay. The effect of SPRR3 on tumor growth in vivo was evaluated in patient-derived xenograft (PDX) models.

Results

SPRR3 was up-regulated in most NSCLC cell lines and clinical tissues. Also, the correlation between SPRR3 expression and clinical features was significant. Functional studies confirmed that SPRR3 modulates cell proliferation, invasion and cell apoptosis in NSCLC via regulating EZH2, which is a well-known oncogene in NSCLC. Furthermore, SPRR3 was found to be a direct target of miR-876-3p that also plays a suppressor role in NSCLC.

Conclusion

These findings indicated that miR-876-3p/SPRR3/EZH2 signaling cascade exerts important roles in the regulation of NSCLC, suggesting that this pathway can serve as a potential therapeutic target in NSCLC.

Co-targeting PLK1 and mTOR induces synergistic inhibitory effects against esophageal squamous cell carcinoma

Both polo-like kinase 1 (PLK1) and mammalian/mechanistic target of rapamycin (mTOR) are attractive therapeutic targets for cancer therapy. However, the efficacy of the combined inhibition of both pathways for treating esophageal squamous cell carcinoma (ESCC), an aggressive malignancy with poor prognosis, remains unknown. In this study, we found that suppression of PLK1 by specific siRNA or inhibitor attenuated mTOR activity in ESCC cells. Phosphorylated S6, a downstream effector of mTOR signaling, was significantly correlated with overexpression of PLK1 in a subset of ESCC. These data suggest that PLK1 activates mTOR signaling in vitro and in vivo. More importantly, the mTOR inhibitor rapamycin synergized with PLK1 inhibitor BI 2536 to inhibit ESCC cell proliferation in culture and in mice. Notably, combined treatment with BI 2536 and rapamycin produced more potent inhibitory effects on the activation of S6 and AKT than either alone. Further analysis reveals that PLK1 modulates both mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2) cascades. Therefore, dual inhibition of PLK1 and mTOR yields stronger antitumor effects, at least partially due to synergistic abrogated the activation of S6, eukaryotic initiation factor 4E-binding protein 1 (4E-BP1), and AKT by cooperatively blocking mTORC1 and mTORC2 cascades. These results provide evidence that the mTOR inhibitor rapamycin synergistically enhances the antitumor effect of PLK1 inhibitor BI 2536 in ESCC cells. Simultaneous targeting of PLK1 and mTOR may thus be a novel and promising therapeutic strategy for ESCC.

KEY MESSAGES

PLK1 potentiates both mTORC1 and mTORC2 activities in ESCC cells. PLK1 expression positively correlated with mTOR activity in a subset of ESCC. Co-targeting of PLK1 and mTOR produced stronger antitumor effects partially due to synergistic inhibition of AKT, 4E-BP1 and S6 through cooperatively blocking mTORC2 and mTORC1 cascades. Combination targeting of PLK1 and mTOR may be a novel and promising therapeutic strategy for ESCC treatment.

PLK1 protects against sepsis-induced intestinal barrier dysfunction

Sepsis and sepsis-associated intestinal barrier dysfunction are common in intensive care units, with high mortality. The aim of this study is to investigate whether Polo-like kinase 1 (PLK1) ameliorates sepsis-induced intestinal barrier dysfunction in the intestinal epithelium. The mouse intestinal barrier was disrupted after Lipopolysaccharide (LPS) injection due to intestinal epithelial cell apoptosis and proliferation inhibition, accompanied by decreased PLK1. In HT-29 intestinal epithelial cells, LPS stimulation induced cell apoptosis and inhibited cell proliferation. Overexpression of PLK1 partly rescued the apoptosis and proliferation inhibition in HT29 cells caused by LPS. Finally, LPS stimulation promoted the reduction of PLK1, resulting in apoptosis and proliferation inhibition in intestinal epithelial cells, disrupting the intestinal epithelial barrier. These findings indicate that PLK1 might be a potential therapeutic target for the treatment of sepsis-induced intestinal barrier dysfunction.

C-Jun expression in lichen planus, psoriasis, and cutaneous squamous cell carcinoma, an immunohistochemical study

The AP-1 transcription factor complex is a key player in regulating inflammatory processes, cell proliferation, differentiation, and cell transformation. The aim of the present study is to investigate C-Jun (one of AP-1complex) expression and its proliferative role in skin samples of lichen planus, psoriasis as common inflammatory skin diseases and squamous cell carcinoma using immunohistochemical method. The present study was carried out on skin biopsies of 15 psoriatic patients, 15 lichen planus patients, 15 SCC, and 15 normal skin biopsies. Nuclear expression of C-Jun was detected in basal and few suprabasal layers of epidermis of normal skin. C-Jun was expressed in the whole epidermal layers of both psoriasis (14/15) and lichen planus (15/15) in addition to its expression in lymphocytic infiltrate in the latter in about half of cases (8/15). C-Jun was also expressed in 93.3% (14/15) of SCC in a percentage lower than that of psoriasis, lichen planus, and normal skin. The percentage of C-Jun expression in SCC was significantly associated with an early stage (p = 0.000), free surgical margins (p = 0.022), and small tumour size (p = 0.003).

CONCLUSIONS

The marked reduction of C-Jun in SCC in comparison to normal skin and inflammatory skin dermatoses may refer to its tumour suppressor activity. C-Jun expression in SCC carries favourable prognosis. Absence of significant association between C-Jun and Ki-67 either in SCC or inflammatory skin diseases indicates that it does not affect proliferative capacity of cells.

Microtubule-associated protein 4 is an important regulator of cell invasion/migration and a potential therapeutic target in esophageal squamous cell carcinoma

Cell invasion and migration significantly contribute to tumor metastasis. Microtubule-associated protein 4 (MAP4) protein is one member of microtubule-associate proteins family. It is responsible for stabilization of microtubules by modulation of microtubule dynamics. However, there is little information about the involvement of MAP4 in human cancer. Here we show that MAP4 serves as a regulator of invasion and migration in esophageal squamous cancer cells. By activating the ERK-c-Jun-vascular endothelial growth factor A signaling pathway, MAP4 promotes cell invasion and migration in vitro, tumor growth and metastasis in mouse models. Immunohistochemical staining of operative tissues indicated that MAP4 expression was associated with tumor stage, lymph node metastasis and shorter survival of the patients with esophageal squamous cell carcinoma (ESCC). Multivariate Cox regression analysis showed that MAP4 is an independent prognostic indicator. In the serial sections of ESCC tissues, there was a positive correlation between MAP4 and vascular endothelial growth factor A expression. Notably, an intratumoral injection of MAP4-small interfering RNA (siRNA) remarkably inhibited the growth of the tumors that formed by the MAP4-expressing ESCC cells in nude mice, and a combination of MAP4-siRNA and Bevacizumab significantly enhanced the inhibition effect. Our data suggest that MAP4 is probably a useful prognostic biomarker and a potential therapeutic target for the disease.

Differentiation-associated genes regulated by c-Jun and decreased in the progression of esophageal squamous cell carcinoma

Transcription factor c-Jun plays a key role in controlling epithelium cell proliferation, apoptosis and differentiation. However, molecular mechanism and biological functions of c-Jun in squamous differentiation and the progression of esophageal squamous cell carcinoma (ESCC) remain elusive. In this study, we found that c-Jun bound directly to the promoter region, and activated the transcription of differentiation-associated genes including cystatin A, involucrin and SPRR3 in vivo. Ectopic expression of c-Jun enhanced SPRR3 transactivation in KYSE450 cells. Conversely, TAM67, a dominant negative mutant of c-Jun, inhibited SPRR3 transactivation. c-Jun increased expression of SPPR3 mainly via a PKC/JNK pathway in response to TPA in KYSE450 cells. Furthermore, c-Jun was remarkably reduced in esophageal cancer. Interestingly, cystatin A, involucrin and SPRR3 were significantly downregulated as well, and associated with differentiation grade. Expression of c-Jun was correlated with the expression of these genes in normal epithelium and ESCC. Importantly, the expression of these genes was remarkably decreased during the malignant transformation from normal epithelium to low-grade intraepithelial neoplasia (LGIN) or high-grade intraepithelial neoplasia (HGIN). The expression of cystatin A and involucrin was significantly reduced from LGIN to HGIN. These results suggest c-Jun was involved in the regulation of differentiation-associated genes in ESCC. These genes might serve as the potential markers in distinguishing normal epithelium from esophageal squamous intraepithelial neoplasia.

Expression of SPRR3 is associated with tumor cell proliferation and invasion in glioblastoma multiforme

Esophagin, also known as small proline-rich protein 3 (SPRR3), has been demonstrated to be important in the initiation and progression of numerous types of tumor, including colorectal and breast cancer. However, studies concerning the biological functions of SPRR3 in glioblastoma multiforme (GBM) are limited. Therefore, we aimed to identify the functions and molecular mechanisms underlying the role of SPRR3 in GBM. Hypomethylation of SPRR3 was observed and associated with a poor clinical outcome in GBM patients compared with healthy individuals by using gene methylation profiling. The present study was performed to investigate the expression status and effects of SPRR3 in GBM. The U251 cell line was used in the functional analyses. Cell growth was examined by MTT and colony formation assay. Cell invasion was measured using the Transwell invasion assay. The expression of SPRR3 in tissue samples was examined by immunohistochemistry. The results revealed that the overexpression of SPRR3 accelerates U251 cell proliferation and invasion. It was also observed that SPRR3 was markedly upregulated in 72.7% of GBM samples (24/33) compared with the normal tissue. These results suggest that an increased expression of SPRR3 is involved in tumorigenesis.

The potential of molecular markers to improve interventions through the natural history of oesophageal squamous cell carcinoma

EC (oesophageal cancer) is one of the ten most frequent and fatal tumours worldwide and ESCC (oesophageal squamous cell carcinoma) accounts for about 80% of the cases. The first symptoms of ESCC arise late during the progression of the disease and, therefore, the diagnosis is usually done in advanced stages. This leads to an inefficient treatment and consequently to a poor prognosis. Thus, a comprehensive knowledge of ESCC biology is of major importance to identify risk factors, especially in high-incidence areas and biomarkers which could enable ESCC prevention and interventions throughout the natural history of the disease. In this review, we present the current knowledge regarding ESCC aetiology as well as the different genetic and epigenetic alterations already described in this tumour. We also discuss how these alterations could be used to anticipate ESCC diagnosis as well as how they can help improving treatment. A molecular natural history of the disease is proposed pointing out potential markers that may improve interventions at different points of ESCC development. Only when the different layers of complexity behind this tumour are elucidated, it will be possible to successfully perform prevention at different levels.

Small proline-rich repeat protein 3 enhances the sensitivity of esophageal cancer cells in response to DNA damage-induced apoptosis

Small proline-rich repeat protein 3 (SPRR3) has been linked with the altered chemoradiosensitivity, however the underlying molecular mechanisms remain elusive. Here, we report that ectopic overexpression of SPRR3 enhanced the sensitivity of cells in response to DNA damage-induced apoptosis via loss of mitochondrial membrane potential (MMP), and increasing activation of caspase 3 in human esophageal cancer cell lines. Conversely, siRNA knockdown of SPRR3 reduced apoptosis. We found that SPRR3 was localized in mitochondria and interacted with Bcl-2 in vivo, thus facilitating Bax mitochondrial translocation and the subsequent release of cytochrome c, and thereby enhancing cell sensitivity to DNA damage stimuli. In clinical samples, expression of SPRR3 was associated with the pathologic response (P = 0.007 in radiotherapy group, P = 0.035 in preoperative radiotherapy group) and good survival of patients with locally advanced esophageal squamous cell carcinoma (ESCC, P = 0.008). Taken together, our results implicate that SPRR3 might serve as a radiation-sensitive predictor of ESCC.

Identification of PTK6, via RNA sequencing analysis, as a suppressor of esophageal squamous cell carcinoma

BACKGROUND & AIMS

Esophageal squamous cell carcinoma (ESCC) is the most commonly observed histologic subtype of esophageal cancer. ESCC is believed to develop via accumulation of numerous genetic alterations, including inactivation of tumor suppressor genes and activation of oncogenes. We searched for transcripts that were altered in human ESCC samples compared with nontumor tissues.

METHODS

We performed integrative transcriptome sequencing (RNA-Seq) analysis using ESCC samples from 3 patients and adjacent nontumor tissues to identify transcripts that were altered in ESCC tissue. We performed molecular and functional studies of the transcripts identified and investigated the mechanisms of alteration.

RESULTS

We identified protein tyrosine kinase 6 (PTK6) as a transcript that was significantly down-regulated in ESCC tissues and cell lines compared with nontumor tissues or immortalized normal esophageal cell lines. The promoter of the PTK6 gene was inactivated in ESCC tissues at least in part via hypermethylation and histone deacetylation. Knockdown of PTK6 in KYSE30 ESCC cells using small hairpin RNAs increased their ability to form foci, migrate, and invade extracellular matrix in culture and form tumors in nude mice. Overexpression of PTK6 in these cells reduced their proliferation in culture and tumor formation in mice. PTK6 reduced phosphorylation of Akt and glycogen synthase kinase (GSK)3β, leading to activation of β-catenin.

CONCLUSIONS

PTK6 was identified as a transcript that is down-regulated in human ESCC tissues via epigenetic modification at the PTK6 locus. Its product appears to regulate cell proliferation by reducing phosphorylation of Akt and GSK3β, leading to activation of β-catenin. Reduced levels of PTK6 promote growth of xenograft tumors in mice; it might be developed as a marker of ESCC.

Combination of meta-analysis and graph clustering to identify prognostic markers of ESCC

Esophageal squamous cell carcinoma (ESCC) is one of the most malignant gastrointestinal cancers and occurs at a high frequency rate in China and other Asian countries. Recently, several molecular markers were identified for predicting ESCC. Notwithstanding, additional prognostic markers, with a clear understanding of their underlying roles, are still required. Through bioinformatics, a graph-clustering method by DPClus was used to detect co-expressed modules. The aim was to identify a set of discriminating genes that could be used for predicting ESCC through graph-clustering and GO-term analysis. The results showed that CXCL12, CYP2C9, TGM3, MAL, S100A9, EMP-1 and SPRR3 were highly associated with ESCC development. In our study, all their predicted roles were in line with previous reports, whereby the assumption that a combination of meta-analysis, graph-clustering and GO-term analysis is effective for both identifying differentially expressed genes, and reflecting on their functions in ESCC.

Reciprocal activation between PLK1 and Stat3 contributes to survival and proliferation of esophageal cancer cells

BACKGROUND & AIMS

Aberrant activation of the signal transducer and activator of transcription (Stat)3 and overexpression of polo-like kinase (PLK)1 each have been associated with cancer pathogenesis. The mechanisms and significance of dysregulation of Stat3 and PLK1 in carcinogenesis and cancer progression are unclear. We investigated the relationship between Stat3 and PLK1 and the effects of their dysregulation in esophageal squamous cell carcinoma (ESCC) cells.

METHODS

We used immunoblot, quantitative reverse-transcription polymerase chain reaction, immunochemistry, chromatin immunoprecipitation, mobility shift, and reporter assays to investigate the relationship between Stat3 and PLK1. We used colony formation, fluorescence-activated cell sorting, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling, and xenograft tumor assays to determine the effects of increased activation of Stat3 and PLK1 in proliferation and survival of ESCC cells.

RESULTS

Stat3 directly activated transcription of PLK1 in esophageal cancer cells and mouse embryonic fibroblast cell NIH3T3. PLK1 then potentiated the expression of Stat3; β-catenin was involved in PLK1-dependent transcriptional activation of Stat3. This mutual regulation between Stat3 and PLK1 was required for proliferation of esophageal cancer cells and resistance to apoptosis in culture and as tumor xenografts in mice. Furthermore, phosphorylation of Stat3 and overexpression of PLK1 were correlated in a subset of ESCC.

CONCLUSIONS

Stat3 and PLK1 control each other's transcription in a positive feedback loop that contributes to the development of ESCC. Increased activity of Stat3 and overexpression of PLK1 promote survival and proliferation of ESCC cells in culture and in mice.

Quantitative evaluation of SPRR3 expression in esophageal squamous cell carcinoma by qPCR and its potential use as a biomarker

Esophageal squamous cell carcinoma (ESCC) is highly fatal due to late diagnosis and inefficient treatment. Early disease detection could improve diagnosis and patient survival. Esophageal squamous epithelial cells express SPRR3, a member of the small proline-rich protein family, which is downregulated in ESCC. Therefore, SPRR3 expression may be used as a biomarker to follow the transition from healthy mucosa to ESCC. Both SPRR3 mRNA splice variants, v1 and v2, were evaluated by real time PCR in tumor and histologically normal adjacent tissue biopsies from 84 ESCC patients and 18 healthy controls. SPRR3-v1 was most highly expressed in the esophageal mucosa of healthy subjects, with an increasingly lower expression in the adjacent mucosa of ESCC patients and in tumors, respectively. SPRR3-v2 expression was low in normal mucosa and in tumors but it was higher in the adjacent mucosa of ESCC patients. In addition, we found a significant correlation between a lower SPRR3-v1 and SPRR3-v2 expression and age and alcohol consumption, respectively. SPRR3 protein expression presented a good correlation with SPRR3 mRNA expression. Cut-off points to discriminate between healthy mucosa, tumor and adjacent mucosa were determined with receiver operating characteristic (ROC) curves. This analysis showed that SPRR3-v1 expression discriminates the esophageal mucosa of healthy subjects from the adjacent mucosa and the tumor of ESCC patients with high sensitivity and specificity. Our data shows that the quantitative analysis of SPRR3 mRNA is a robust and reliable method to monitor the malignant transformation of the healthy esophageal mucosa into ESCC.

Meta-analysis of cancer gene expression signatures reveals new cancer genes, SAGE tags and tumor associated regions of co-regulation

Cancer is among the major causes of human death and its mechanism(s) are not fully understood. We applied a novel meta-analysis approach to multiple sets of merged serial analysis of gene expression and microarray cancer data in order to analyze transcriptome alterations in human cancer. Our methodology, which we denote ‘COgnate Gene Expression patterNing in tumours’ (COGENT), unmasked numerous genes that were differentially expressed in multiple cancers. COGENT detected well-known tumor-associated (TA) genes such as TP53, EGFR and VEGF, as well as many multi-cancer, but not-yet-tumor-associated genes. In addition, we identified 81 co-regulated regions on the human genome (RIDGEs) by using expression data from all cancers. Some RIDGEs (28%) consist of paralog genes while another subset (30%) are specifically dysregulated in tumors but not in normal tissues. Furthermore, a significant number of RIDGEs are associated with GC-rich regions on the genome. All assembled data is freely available online (www.oncoreveal.org) as a tool implementing COGENT analysis of multi-cancer genes and RIDGEs. These findings engender a deeper understanding of cancer biology by demonstrating the existence of a pool of under-studied multi-cancer genes and by highlighting the cancer-specificity of some TA-RIDGEs.

Upregulation of SPRR3 promotes colorectal tumorigenesis

Hereditary colorectal cancer develops through a series of well-defined genetic and histological changes. However, elucidation of the canonical pathway based on hereditary colorectal cancer has not provided a clear explanation of the molecular mechanisms of sporadic colorectal cancer. To identify the alterative pathways involved in sporadic colorectal tumorigenesis, we performed gene expression analysis in patients with sporadic colorectal tumors. A comparison analysis of gene expression profiles revealed a pattern of upregulation of small proline rich repeat protein 3 (SPRR3) in tumor samples. SPRR3 has previously been reported to be downregulated in esophageal cancer. However, in the present study, we observed that SPRR3 was strongly upregulated in 31 of 35 samples of sporadic colorectal tumors (88%). We also determined that overexpression of SPRR3 not only accelerates colorectal cancer cell proliferation but also is associated with lymphovascular invasion in colorectal cancer. Moreover, AKT was activated and p53 levels were decreased in cells that overexpressed SPRR3. In contrast to the pattern seen in esophageal cancer, these results suggest that increased expression of SPRR3 is involved in colorectal tumorigenesis.

A novel p53 target gene, S100A9, induces p53-dependent cellular apoptosis and mediates the p53 apoptosis pathway

S100A9 (S100 calcium-binding protein A9) is a calcium-binding protein of the S100 family, and its differential expression has been associated with acute and chronic inflammation and several human cancers. Our previous work showed that S100A9 was severely down-regulated in human ESCC (oesophageal squamous cell carcinoma). To further investigate the transcriptional regulation of S100A9, we analysed the S100A9 promoter region and found several putative p53BS (p53-binding sites). Luciferase reporter assays showed that constructs carrying the p53BS exhibited enhanced luciferase activity in response to wild-type p53 activation. Further study demonstrated that S100A9 mRNA and protein expression could be positively regulated in a p53-dependent manner and p53 could bind to p53BS on the S100A9 promoter. Overexpression of S100A9 could induce cellular apoptosis, and this was partly p53-dependent. Knockdown of S100A9 impaired the apoptosis induced by p53. Thus we conclude that a gene down-regulated in ESCC, S100A9, is a novel p53 transcriptional target, induces cellular apoptosis in a partly p53-dependent manner and mediates the p53 apoptosis pathway.