SPRR3 Expression Research Articles

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.

Long Noncoding RNA PCAT18 Upregulates SPRR3 to Promote Colorectal Cancer Progression by Binding to miR-759.

BackgroundLong noncoding RNAs (lncRNAs) play essential functions in the development of several cancers, including colorectal cancer (CRC). Nevertheless, how PCAT18 regulates CRC tumorigenesis remains unclear. In this research, we aimed to investigate the roles of PCAT18 in CRC.Materials and MethodsqRT-PCR and Western blot were used to analyze RNA and protein levels. CCK8, colony formation, transwell and wound healing assays were utilized to analyze proliferation, migration and invasion. Luciferase reporter assay was used to analyze RNA interactions.ResultsPCAT18 was found to be highly expressed in CRC tissues and cells. PCAT18 level was positively correlated with lymph node metastasis and TNM stage. Functionally, PCAT18 silencing induced impairment of CRC proliferation, migration and invasion. Besides, PCAT18 was identified to inhibit miR-759. PCAT18 promotes SPRR3 expression through binding to miR-759. Furthermore, miR-759 inhibitors or SPRR3 ectopic expression partially rescued the abilities of proliferation, migration and invasion in CRC cells transfected with sh-PCAT18.ConclusionTherefore, our study demonstrated that PCAT18 contributes to CRC progression through regulating miR-759/SPRR3 axis, which provides a new theoretical basis of explaining CRC tumorigenesis.

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

BackgroundSPRR3, 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.MethodsThe 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.ResultsSPRR3 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.ConclusionThese 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.

Cigarette smoke upregulates SPRR3 by favoring c-Jun/Fra1 heterodimerization in human bronchial epithelial cells.

The airway epithelium of smokers exhibits upregulated SPRR3, an indicator of pathogenic keratinization. The mechanisms underlying this phenomenon require investigation. Human bronchial epithelial (HBE) SPRR3 expression was analyzed by smoking status. Primary HBE cells were exposed to cigarette smoke (CS). SPRR3 expression, SPRR3 promoter activity, AP-1 factor binding and AP-1 factors' effects were analyzed. Current smokers display SPRR3 upregulation relative to never smokers. CS upregulates SPRR3 transcription in an exposure-dependent manner. CS promotes c-Jun and Fra1 binding to the SPRR3-AP-1/TRE site. Wild-type c-Jun and Fra1 upregulate, whereas c-Jun and Fra1, dominant-negative mutants, suppress SPRR3 promoter activity. CS induces SPRR3 upregulation in HBE cells by promoting aberrant c-Jun/Fra1 dimerization.

PO-391 DNA methylation as a probable cause of SPRR3 loss in esophageal cancer

IntroductionEsophageal cancer (EC) is the eighth most frequent cancer and the sixth leading cause of cancer-related deaths worldwide, with squamous cell carcinoma (ESCC) corresponding to 80% of the cases. SPRR3 is a differentiation-associated gene that belongs to SPRR (small proline rich) family that showed a gradual loss of expression in malignant transformation of the healthy oesophagus into ESCC. However, studies of the molecular mechanisms involved in SPRR3 silencing are limited. Thus, the aim of this study is to examine DNA methylation as a regulatory mechanism of SPRR3 expression in ESCC.Material and methodsThree CpG sites of SPRR3 (A, B for promotor region and C for 5´UTR region) were analysed by pyrosequencing in esophageal cancer cell lines (TE-1, TE-13 and OE21) treated with the demethylating agent decitabine, and in tumour and matched normal surrounding mucosa from patients with ESCC. RT-qPCR was performed to evaluated SPRR3, DNMT1, DNMT3A and DNMT3B expression in the same samples.Results and discussionsDecitabine treatment was able to induce SPRR3 demethylation and reestablished esophagin expression in the three cell lines tested. The methylation of all CpG sites analysed was significantly higher in tumours in comparison with the adjacent tissues (p<0.0001 for the three CpG sites analysed). The ability of SPRR3 methylation to distinguish the adjacent mucosa from tumour samples using ROC curve analyses was significant for each of the CpG sites examined (A, sensitivity 93.10% and specificity=86.21%, p<0.0001; B. sensitivity=88.24% specificity=76.47%, p<0.0001; C, sensitivity=82.35% and specificity=73.53%, p<0.0001). We observed an inverse correlation between esophagin methylation and SPRR3 mRNA expression for all CpG sites evaluated (A and B p<0.0001; C p=0.0007). In order to investigate the mechanisms that could be involved in SPRR3 hypermethylation, we evaluated DNMTs expression (higher expression in tumour in comparision with the normal surrounding mucosa, p<0.0001 DNMT1, p=0.0005 DNMT3A and p<0.0001 DNMT3B) which are inversely correlated with SPRR3 expression (DNMT1 p=0.0013, DNMT3A p=0.0108 and DNMT3B p<0.0001). We observed an inverse correlation between SPRR3 methylation and DNMTs mRNA expression for all CpG sites evaluated exceptd for DNMT3A and Site C.ConclusionThus, our data provide evidences that DNA methylation induced by DNMTs is a possible mechanism involved for SPRR3 silencing in ESCC.

Identification of small proline-rich repeat protein 3 as a novel atheroprotective factor that promotes adaptive Akt signaling in vascular smooth muscle cells.

Atherosclerosis is the primary driver of cardiovascular disease, the leading cause of death worldwide. Identification of naturally occurring atheroprotective genes has become a major goal for the development of interventions that will limit atheroma progression and associated adverse events. To this end, we have identified small proline-rich repeat protein (SPRR3) as selectively upregulated in vascular smooth muscle cells (VSMCs) of atheroma-bearing arterial tissue versus healthy arterial tissue. In this study, we sought to determine the role of SPRR3 in atheroma pathophysiology. We found that atheroprone apolipoprotein E-null mice lacking SPRR3 developed significantly greater atheroma burden. To determine the cellular driver(s) of this increase, we evaluated SPRR3-dependent changes in bone marrow-derived cells, endothelial cells, and VSMCs. Bone marrow transplant of SPRR3-expressing cells into SPRR3(-/-)apolipoprotein E-deficient recipients failed to rescue atheroma burden. Similarly, endothelial cells did not exhibit a response to SPRR3 loss. However, atheromas from SPRR3-deficient mice exhibited increased TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling)-positive VSMCs compared with control. Cell death in SPRR3-deficient VSMCs was significantly increased in vitro. Conversely, SPRR3-overexpressing VSMCs exhibited reduced apoptosis compared with control. We also observed a PI3K (phosphatidylinositol 3-kinase)/Akt-dependent positive association between SPRR3 expression and levels of active Akt in VSMCs. The survival advantage seen in SPRR3-overexpressing VSMCs was abrogated after the addition of a PI3K/Akt pathway inhibitor. These results indicate that SPRR3 protects the lesion from VSMC loss by promoting survival signaling in plaque VSMCs, thereby significantly decreasing atherosclerosis progression. As the first identified atheroma-specific VSMC prosurvival factor, SPRR3 represents a potential target for lesion-specific modulation of VSMC survival.

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.

Regulation of the Atheroma-Enriched Protein, SPRR3, in Vascular Smooth Muscle Cells through Cyclic Strain is Dependent on Integrin α1β1/Collagen Interaction

Atherosclerotic plaques express high levels of small proline-rich repeat protein (SPRR3), a previously characterized component of the cornified cell envelope of stratified epithelia, where it is believed to play a role in cellular adaptation to biomechanical stress. We investigated the physiological signals and underlying mechanism(s) that regulate atheroma-enriched SPRR3 expression in vascular smooth muscle cells (VSMCs). We showed that SPRR3 is expressed by VSMCs in both human and mouse atheromas. In cultured arterial VSMCs, mechanical cyclic strain, but neither shear stress nor lipid loading induced SPRR3 expression. Furthermore, this upregulation of SPRR3 expression was dependent on VSMC adherence to type I collagen. To link the mechanoregulation of SPRR3 to specific collagen/integrin interactions, we used blocking antibodies against either integrin alpha1 or alpha2 subunits and VSMCs from mice that lack specific collagen receptors. Our results showed a dependence on the alpha1beta1 integrin for SPRR3 expression induced by cyclic strain. Furthermore, we showed that integrin alpha1 but not alpha2 subunits were expressed on VSMCs within mouse lesions but not in normal arteries. Therefore, we identified the enrichment of the mechanical strain-regulated protein SPRR3 in VSMCs of both human and mouse atherosclerotic lesions whose expression is dependent on the collagen-binding integrin alpha1beta1 on VSMCs. These data suggest that SPRR3 may play a role in VSMC adaptation to local biomechanical stress within the plaque microenvironment.

Enrichment of Genes in the Aortic Intima That Are Associated With Stratified Epithelium

Arteries and veins are exposed to different pressures and are easily distinguished by morphology. Although several recent studies have focused on differential gene expression between the arterial and venous endothelium, the molecular distinctions that give rise to the dramatic structural distinctions between arteries and veins, such as in the organization of the intima, are not known. We used high-density oligonucleotide arrays to analyze the transcriptional profile of the mouse aorta and inferior vena cava (IVC), not restricting our analysis to the endothelium, to identify genes whose expression was enriched in aorta over other tissues and the IVC. By quantitative reverse transcription-polymerase chain reaction analysis, these genes have been shown to be highly expressed in the mouse aorta and were either expressed at low levels or were undetectable in the murine IVC. By immunofluorescence analysis of human tissue, we determined that a subset of these aorta-enriched proteins exhibited a primarily intima-restricted expression. Intimal expression of at least a subset of these genes, plakoglobin, galectin 7, sciellin, and SPRR3, was also detected in other types of arteries but not in veins. Furthermore, SPRR3 expression in the intima was primarily associated with atheromas. The proteins identified are functionally related in that they are known to also be enriched in stratified epithelia, where they play an important role in stress-bearing and barrier properties. Vascular expression of these genes has not been reported previously. Our observations suggest that they may play a significant role in the mechanisms by which large arteries may adapt to biomechanical stress.

Decreased expression of SPRR3 in Chinese human oesophageal cancer.

cDNA fragments that were differentially expressed between human oesophageal carcinomas and matched normal adjacent mucosa were isolated using an improved mRNA differential display technique. One of them was identified as the 3'-untranslated region of SPRR3 and was homologous to the esophagin cDNA. Northern blot, dot blot and reverse transcription-polymerase chain reaction (RT-PCR) analyses revealed that SPRR3 expression was lost in three cell lines of oesophageal carcinoma and was dramatically decreased in 54 out of 57 primary oesophageal carcinomas compared with adjacent normal mucosa. Esophagin has been shown to be down-regulated in western oesophageal carcinomas. The data suggest that esophagin is probably the protein product of the gene SPRR3 and that altered mRNA expression of SPRR3/esophagin is a frequent event in the development of Chinese oesophageal cancer.

Expression of small proline rich proteins in neoplastic and inflammatory skin diseases.

The formation of the cornified cell envelope (CE) during the late stages of epidermal differentiation is essential for epidermal barrier function and protects the body against environmental attack and water loss. Formation of the CE involves the replacement of the plasma membrane by cross-linkage of precursor proteins such as involucrin, small proline rich proteins (SPRR) and loricrin. In normal epidermis, SPRR1 is restricted to appendages, SPRR2 is also expressed in interfollicular areas, while SPRR3 is completely absent; the latter is most abundant in oral epithelium. This differential expression indicates an important part for SPRRs in specific barrier requirements, and reflects their importance in the biomechanical properties of the CE. We report here on the expression of SPRR1, SPRR2 and SPRR3 in a wide range of cutaneous neoplastic and inflammatory diseases. We used immunohistochemistry; in addition, Northern blot analysis of malignant tumours was performed. Increased suprabasal expression of SPRR1 and SPRR2, but no SPRR3 expression, was noted in inflammatory dermatoses with orthokeratotic and parakeratotic squamous differentiation. By contrast, differentiating epidermal tumours such as Bowen's disease, keratoacanthoma and squamous cell carcinoma expressed SPRR3. As SPRRs were originally cloned on the basis of their expression in ultraviolet light-irradiated keratinocytes, the expression of SPRR3 in actinic lesions is of interest, and might serve as a diagnostic tool.

Temperature-sensitive regulation of epidermal morphogenesis and the expression of cornified envelope precursors by EGF and TGF alpha.

Epidermis reconstructed on de-epidermized dermis was used to investigate the effects of growth factors and culture temperature on epidermal morphogenesis and the expression of cornified envelope precursors. Cultures grown at 33 degreesC or 37 degreesC in the absence or presence of transforming growth factor alpha (TGFalpha), keratinocyte growth factor (KGF), basic fibroblast growth factor (bFGF), or insulin-like growth factor (IGF) show a similar morphology to that of native epidermis. Loricrin and SPRR2 are expressed in the stratum granulosum and SPRR3 is absent. Cultures grown in epidermal growth factor (EGF)-supplemented medium at 37 degrees C have a normal morphology, whereas cultures grown at 33 degrees C have a disorganized basal layer, no stratum granulosum, and nuclei are present in the stratum corneum. Loricrin is absent, and SPRR2 and SPRR3 expression extend into the spinous layers. Irrespective of the culture condition used, involucrin is aberrantly expressed in all suprabasal layers. EGF stimulated keratinocyte proliferation and migration to a greater degree than TGFalpha. Epidermis reconstructed on fibroblast-populated collagen gels at 33 degrees C led to the same disturbances in keratinocyte differentiation as seen in cultures grown on de-epidermized dermis at 33 degrees C in the presence of EGF, whereas parallel cultures grown at 37 degrees C have a similar morphology to that of native epidermis.