Decreased expression of Calpain-9 predicts unfavorable prognosis in patients with gastric cancer

Nicotine reduces ROS and enhances cell proliferation via the α4 nicotinic acetylcholine receptor subunit in human induced pluripotent stem cells

The effects of smoking on fetal development and stem cell differentiation are not fully understood. Although nicotinic acetylcholine receptors (nAChRs) are expressed in many organs of the human body, their significance in human induced pluripotent stem cells (hiPSCs) remains unclear. After expression levels of nAChR subunits in hiPSCs were determined, the effects of the nAChR agonist, nicotine, on undifferentiated hiPSCs were evaluated using a Clariom S Array. We also determined the effect of nicotine alone and with a nAChR subunit antagonist on hiPSC cells. NAChR α4, α7, and β4 subunits were strongly expressed in hiPSCs. cDNA microarray, gene ontology, and enrichment analyses showed that exposing hiPSCs to nicotine altered expression of genes associated with immune responses, neurological system, carcinogenesis, cell differentiation, and cell proliferation. Particularly affected was metallothionein, which acts to decrease reactive oxygen species (ROS). The nicotine-induced reduction of ROS in hiPSCs was canceled by an α4 subunit or nonselective nAChR antagonist. HiPSC proliferation was increased by nicotine, and this effect, too, was canceled by an α4 antagonist. In conclusion, nicotine reduces ROS and enhances cell proliferation via the α4 nAChR subunit in hiPSCs. These findings provide new insight into the significance of nAChRs on human stem cells and fertilized human ova.

Comprehensive Analysis of the Effects of Genetic Ancestry and Genetic Characteristics on the Clinical Evolution of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC), a kind of malignant cancer, is associated with increasing morbidity and mortality. Patients with different genetic ancestries may respond differently to clinical treatment. The limited understanding of the influence of genetic ancestry and genetic characteristics on OSCC impedes the development of precision medicine. To provide a reference for clinical treatment, this study comprehensively analyzed multigenomic differences in OSCC patients with different genetic ancestries and their impact on prognosis. An analysis of data from OSCC patients with different genetic ancestries in The Cancer Genome Atlas (TCGA) showed that the overall survival (OS) of African (AFR) patients was lower than that of primarily European (EUR) patients, and differences were also observed in the tumor-stroma ratio (TSR) and tumor-infiltrating lymphocytes (TILs), which are associated with prognosis. FAT1 is a key mutant gene in OSCC, and it has inconsistent effects on clinical evolution for patients with diverse genetic characteristics. PIKfyve and CAPN9 showed a significant difference in mutation frequency between EUR and AFR; PIKfyve was related to Ki-67 expression, suggesting that it could promote tumor proliferation, and CAPN9 was related to the expression of Bcl-2, promoting tumor cell apoptosis. A variant methylation locus, cg20469139, was correlated with the levels of PD-L1 and Caspase-7 and modulated tumor cell apoptosis. A novel ceRNA model was constructed based on genetic ancestries, and it could accurately evaluate patient prognosis. More importantly, although T cell dysfunction scores could determine the potential of tumor immune escape, the efficacy was obviously affected by patients' genetic ancestries. To provide patients with more precise, personalized therapy and to further improve their quality of life and 5-year survival rate, the influence of genetic ancestry should be fully considered when selecting treatments.

Comprehensive analysis of prognostic value and immune infiltration of calpains in pancreatic cancer

BACKGROUND

Calpains (CAPNs) are intracellular calcium-activated neutral cysteine proteinases involved in cancer initiation, progression, and metastasis. However, its role in pancreatic cancer (PC) is still unclear. This study aims to identify the prognostic value and immune infiltration of CAPNs for PC patients using comprehensive bioinformatics analyzes.

METHODS

We analyzed the transcription levels of CAPNs in different cancers from Oncomine, differential gene expression in tumor/normal tissues and pathological stage through GEPIA database, the prognostic value of the mRNA expression of CAPNs by Kaplan-Meier plotter, the protein expression comparison of different CAPNs in human tumor/normal tissues from The Human Protein Atla, the CAPNs gene alterations through cBioPortal, the prediction of protein-protein interactions by STRING and GeneMANIA, the functional enrichment of discrepant CAPNs by GO and KEGG, and the immune infiltration of CAPNs by ssGSEA.

RESULTS

Our results showed that CAPN1, 2, 4, 5, 6, 8, 9, 10, and 12 were highly expressed in PC. CAPN1, 5, 8, and 12 expression levels were positively correlated with individual cancer stages. Furthermore, CAPN1, 2, 5, and 8 expression levels were negatively correlated with overall survival (OS) and recurrence-free survival (RFS), while CAPN10 was positively correlated with OS and RFS. We found that CAPN1, 2, 5, and 8 were correlated with tumor-infiltrating T follicular helper cells and CAPN10 with tumor-infiltrating T helper 2 cells. Functional enrichment analysis showed that differentially expressed CAPNs (CAPN1, 2, 5, 8, and 10) are involved in axonogenesis, cell-substrate adhesion, immune response-activating cell surface receptor signaling pathway, and cell junction organization in PC.

CONCLUSIONS

These results suggested that CAPN1, 2, 5, 8, and 10 could be used as prognostic biomarkers in PC and improve individualized treatment strategies.

A Novel Calpain Inhibitor Compound Has Protective Effects on a Zebrafish Model of Spinocerebellar Ataxia Type 3

Spinocerebellar ataxia type 3 (SCA3) is a hereditary ataxia caused by inheritance of a mutated form of the human ATXN3 gene containing an expanded CAG repeat region, encoding a human ataxin-3 protein with a long polyglutamine (polyQ) repeat region. Previous studies have demonstrated that ataxin-3 containing a long polyQ length is highly aggregation prone. Cleavage of the ataxin-3 protein by calpain proteases has been demonstrated to be enhanced in SCA3 models, leading to an increase in the aggregation propensity of the protein. Here, we tested the therapeutic potential of a novel calpain inhibitor BLD-2736 for the treatment of SCA3 by testing its efficacy on a transgenic zebrafish model of SCA3. We found that treatment with BLD-2736 from 1 to 6 days post-fertilisation (dpf) improves the swimming of SCA3 zebrafish larvae and decreases the presence of insoluble protein aggregates. Furthermore, delaying the commencement of treatment with BLD-2736, until a timepoint when protein aggregates were already known to be present in the zebrafish larvae, was still successful at removing enhanced green fluorescent protein (EGFP) fused-ataxin-3 aggregates and improving the zebrafish swimming. Finally, we demonstrate that treatment with BLD-2736 increased the synthesis of LC3II, increasing the activity of the autophagy protein quality control pathway. Together, these findings suggest that BLD-2736 warrants further investigation as a treatment for SCA3 and related neurodegenerative diseases.

MiR-585-3p suppresses tumor proliferation and migration by directly targeting CAPN9 in high grade serous ovarian cancer

Background

Aberrant expression of microRNAs (miRNAs) contributes to the development of high grade serous ovarian cancer (HGSOC). However, the molecular mechanism by which miRNA-585-3p mediates high-grade serous ovarian carcinogenesis is unclear. This study aims to investigate the specific mechanism of action of miR-585-3p in HGSOC.

Methods

Expression of miR-585-3p in HGSOC tissues and cell lines was detected by qRT-PCR. Cell viability and migration were detected using MTT and transwell system. The expression of target genes and target proteins of miR-585-3p was detected by dual luciferase reporter assay and western blot.

Results

The expression of miR-585-3p was significantly lower in HGSOC tissues and cells than in normal ovarian tissues and cell lines. In HGSOC tissues, CAPN9 expression was inversely correlated with miR-585-3p expression. MiR-585-3p inhibited the proliferation and migration of HGSOC cells. MiR-585-3p bound to the 3'-untranslated region (UTR) of CAPN9 and inhibits CAPN9 expression. Overexpression of CAPN9 reduced the inhibitory effect of miR-585-3p in HGSOC cells.

Conclusions

miR-585-3p is significantly down-regulated in HGSOC tissues and cell lines. MiR-585-3p inhibits the proliferation and migration of HGSOC cells by targeting CAPN9.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-021-00841-w.

Screening of immunosuppressive cells from colorectal adenocarcinoma and identification of prognostic markers

Background: Colorectal cancer (CRC) is the most common type of gastrointestinal malignant tumour. Colorectal adenocarcinoma (COAD) – the most common type of CRC – is particularly dangerous. The role of the immune system in the development of tumour-associated inflammation and cancer has received increasing attention recently.

Methods: In the present study, we compiled the expression profiles of 262 patients with complete follow-up data from The Cancer Genome Atlas (TCGA) database as an experimental group and selected 65 samples from the Gene Expression Omnibus (GEO) dataset (of which 46 samples were with M0) as a verification group. First, we screened the immune T helper 17 (Th17) cells related to the prognosis of COAD. Subsequently, we identified Th17 cells-related hub genes by utilising Weighted Gene Co-expression Network Analysis (WGCNA) and Least Absolute Shrinkage and Selector Operation (LASSO) regression analysis. Six genes associated with the prognosis in patients with COAD were identified, including: KRT23, ULBP2, ASRGL1, SERPINA1, SCIN, and SLC28A2. We constructed a clinical prediction model and analysed its predictive power.

Results: The identified hub genes are involved in developing many diseases and closely linked to digestive disorders. Our results suggested that the hub genes could influence the prognosis of COAD by regulating Th17 cells’ infiltration.

Conclusions: These newly discovered hub genes contribute to clarifying the mechanisms of COAD development and metastasis. Given that they promote COAD development, they may become new therapeutic targets and biomarkers of COAD.

Deciphering the Role of Ca2+ Signalling in Cancer Metastasis: From the Bench to the Bedside

Metastatic cancer is one of the major causes of cancer-related mortalities. Metastasis is a complex, multi-process phenomenon, and a hallmark of cancer. Calcium (Ca2+) is a ubiquitous secondary messenger, and it has become evident that Ca2+ signalling plays a vital role in cancer. Ca2+ homeostasis is dysregulated in physiological processes related to tumour metastasis and progression-including cellular adhesion, epithelial-mesenchymal transition, cell migration, motility, and invasion. In this review, we looked at the role of intracellular and extracellular Ca2+ signalling pathways in processes that contribute to metastasis at the local level and also their effects on cancer metastasis globally, as well as at underlying molecular mechanisms and clinical applications. Spatiotemporal Ca2+ homeostasis, in terms of oscillations or waves, is crucial for hindering tumour progression and metastasis. They are a limited number of clinical trials investigating treating patients with advanced stages of various cancer types. Ca2+ signalling may serve as a novel hallmark of cancer due to the versatility of Ca2+ signals in cells, which suggests that the modulation of specific upstream/downstream targets may be a therapeutic approach to treat cancer, particularly in patients with metastatic cancers.

Genome-Wide Analysis of the FOXA1 Transcriptional Network Identifies Novel Protein-Coding and Long Noncoding RNA Targets in Colorectal Cancer Cells

Differentiation status of tumors is correlated with metastatic potential and malignancy. FOXA1 (forkhead box A1) is a transcription factor known to regulate differentiation in certain tissues. Here, we investigate FOXA1 function in human colorectal cancer (CRC). We found that FOXA1 is robustly expressed in the normal human colon but significantly downregulated in colon adenocarcinoma. Applying FOXA1 chromatin immunoprecipitation coupled with deep sequencing and transcriptome analysis upon FOXA1 knockdown in well-differentiated CRC cells and FOXA1 overexpression in poorly differentiated CRC cells, we identified novel protein-coding and lncRNA genes regulated by FOXA1. Among the numerous novel FOXA1 targets we identified, we focused on CEACAM5, a tumor marker and facilitator of cell adhesion. We show that FOXA1 binds to a distal enhancer downstream of CEACAM5 and strongly activates its expression. Consistent with these data, we show that FOXA1 inhibits anoikis in CRC cells. Collectively, our results uncover novel protein-coding and noncoding targets of FOXA1 and suggest a vital role of FOXA1 in enhancing CEACAM5 expression and anoikis resistance in CRC cells.

CAPN6 in disease: An emerging therapeutic target (Review)

As a member of the calpain protein family, calpain6 (CAPN6) is highly expressed mainly in the placenta and embryos. It plays a number of important roles in cellular processes, such as the stabilization of microtubules, the main-tenance of cell stability, the control of cell movement and the inhibition of apoptosis. In recent years, various studies have found that CAPN6 is one of the contributing factors associated with the tumorigenesis of uterine tumors and osteosarcoma, and that CAPN6 participates in the development of tumors by promoting cell proliferation and angiogenesis, and by inhibiting apoptosis, which is mainly regulated by the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt) pathway. Due to its abnormal cellular expression, CAPN6 has also been found to be associated with a number of diseases, such as white matter damage and muscular dystrophy. Therefore, CAPN6 may be a novel therapeutic target for these diseases. In the present review, the role of CAPN6 in disease and its possible use as a target in various therapies are discussed.

Digenic inheritance of MSH6 and MUTYH variants in familial colorectal cancer

We describe a family severely affected by colorectal cancer (CRC) where whole-exome sequencing identified the coinheritance of the germline variants encoding MSH6 p.Thr1100Met and MUTYH p.Tyr179Cys in, at least, three CRC patients diagnosed before 60 years of age. Digenic inheritance of monoallelic MSH6 variants of uncertain significance and MUTYH variants has been suggested to predispose to Lynch syndrome-associated cancers; however, cosegregation with disease in the familial setting has not yet been established. The identification of individuals carrying multiple potential cancer risk variants is expected to rise with the increased application of whole-genome sequencing and large multigene panel testing in clinical genetic counseling of familial cancer patients. Here we demonstrate the coinheritance of monoallelic variants in MSH6 and MUTYH consistent with cosegregation with CRC, further supporting a role for digenic inheritance in cancer predisposition.

lncRNA SPRY4-IT1 Regulates Cell Proliferation and Migration by Sponging miR-101-3p and Regulating AMPK Expression in Gastric Cancer

Increasing evidence indicates that long noncoding RNA SPRY4 intronic transcript 1 (lncRNA SPRY4-IT1) has been reported to be associated with the progression of several cancers, but its expression level and the function of SPRY4-IT1 in the progression of gastric cancer (GC) have been rarely reported. Here we found that SPRY4-IT1 was upregulated in GC. In vitro experiments revealed that SPRY4-IT1 knockdown significantly inhibited GC cell proliferation by causing G1 arrest and promoting apoptosis, whereas SPRY4-IT1 overexpression promoted cell growth. Further functional assays indicated that SPRY4-IT1 overexpression significantly promoted cell migration and invasion. Bioinformatics analysis predicted that there is a SPRY4-IT1/miR-101-3p/AMPK axis in GC progression. A dual-luciferase reporter system validated the direct interaction of SPRY4-IT1, miR-101-3p, and AMPK. Western blot verified that the inhibition of SPRY4-IT1 decreased AMPK expression. Furthermore, silencing SPRY4-IT1 suppressed GC growth in vivo. Importantly, we demonstrated that SPRY4-IT1 was upregulated in serum exosomes from GC patients and correlated with cancer metastasis. Altogether, silencing SPRY4-IT1 suppresses the progression of GC by interacting with miR-101-3p and decreasing inhibiting AMPK expression. Taken together, our study demonstrates that SPRY4-IT1 could act as a potential therapeutic target for GC patients.

1,25-Dihydroxyvitamin D3 affects gastric cancer progression by repressing BMP3 promoter methylation

Background

Vitamin D₃ has been known to have an anticancer effect, but the mechanisms underlying this is poorly explored. The present study aimed to investigate the antitumor role of vitamin D₃ on gastric cancer and mechanisms.

Methods

The Roche Elecsys platform was applied in retrospective studies to detect the role of 25-hydroxylvitamin D₃ in adenocarcinoma and colony formation assay was conducted to verify the effect of 1, 25-dihydroxyvitamin D₃ on the proliferation of gastric cancer cells. After the identification of hypermethylation of BMP3 CpG islands by bisulfite genomic sequencing (BGS), we further investigated the relationship of BMP3 expression and gastric carcinogenesis by Western blot analysis and gel electrophoresis mobility shift assay (EMSA).

Results

Here we show that low concentration of 1, 25-dihydroxyvitamin D₃ links to can-cerization and significantly inhibits proliferation of undifferentiated gastric cancer cell lines SGC-7901 and BGC-823. BMP3 promoter hypermethylation was highly correlated with gastric tumor. Moreover, BMP3 expression was regulated by its promoter methylation in gastric cells. The further exploration of the relationship between 1, 25-dihydroxyvitamin D₃ and BMP3 by EMSA results that 1, 25-dihydroxyvitamin D₃ stimulates BMP3 expression by the inhibition of BMP3 promoter methylation in gastric tumor cells.

Conclusion

In combination with the data from clinical research, bioinformatics analysis and experimental verification, we propose that 1, 25-hydroxylvitamin D₃ affects gastric cancer progression by repressing BMP3 promoter methylation.

Genome-wide association study identifies variants in the CAPN9 gene associated with umbilical hernia in pigs

Pig umbilical hernia (UH) affects pig welfare and brings considerable economic loss to the pig industry. To date, the molecular mechanisms underlying pig UH are still poorly understood. To identify potential loci for susceptibility to this disease, we performed a genome-wide association study in an Erhualian × Shaziling F₂ intercross population. A total of 45 animals were genotyped using Illumina Porcine SNP60 BeadChips. We observed a SNP (rs80993347) located in the calpain-9 (CAPN9) gene on Sus scrofa chromosome 14 that was significantly associated with UH (P = 1.97 × 10^-10 ). Then, we identified a synonymous mutation rs321865883 (g.20164T>C) in exon 10 of the CAPN9 gene that distinguished two affected individuals (CC) from their normal full-sibs (TC). Finally, quantitative polymerase chain reaction was explored to investigate the mRNA expression profile of the CAPN9 gene in 12 tissues in Yorkshire pigs at different developmental stages (3, 90 and 180 days). CAPN9 showed high expression levels in the gastrointestinal tract at these three growth stages. The results of this study indicate that the CAPN9 gene might be implicated in UH. Further studies are required to establish a role of CAPN9 in pig UH.

Evidence for calpains in cancer metastasis

Metastatic dissemination represents the final stage of tumor progression as well as the principal cause of cancer-associated deaths. Calpains are a conserved family of calcium-dependent cysteine proteinases with ubiquitous or tissue-specific expression. Accumulating evidence indicates a central role for calpains in tumor migration and invasion via participating in several key processes, including focal adhesion dynamics, cytoskeletal remodeling, epithelial-to-mesenchymal transition, and apoptosis. Activated after the increased intracellular calcium concentration ( [ Ca 2 + ] i ) induced by membrane channels and extracellular or intracellular stimuli, calpains induce the limited cleavage or functional modulation of various substrates that serve as metastatic mediators. This review covers established literature to summarize the mechanisms and underlying signaling pathways of calpains in cancer metastasis, making calpains attractive targets for aggressive tumor therapies.

Calpain-2 triggers prostate cancer metastasis via enhancing CRMP4 promoter methylation through NF-κB/DNMT1 signaling pathway

BACKGROUND

Metastasis is the major cause of cancer-specific death in patients with prostate cancer (PCa). We previously reported that collapsing response mediator protein-4 (CRMP4) is a PCa metastasis-suppressor gene and the hypermethylation in CRMP4 promoter is responsible for the transcription repression in metastatic PCa. However, the underlying mechanisms remain unknown. In this study, we aimed to investigate the role of calpain-2 in CRMP4 promoter hypermethylation and its functional modulation in PCa metastasis.

METHODS

Calpain-2 expression in PCa tissues (n = 87) and its specific mechanisms of functional modulation in CRMP4 expression via limited enzymatic cleavage was investigated. We then focused on the cooperative crosstalk of calpain-2 and NF-κB RelA/p65 in CRMP4 promoter methylation for the initiation of PCa metastasis. Statistical differences between groups were determined using a two-tailed Student's t-test. P < 0.05 indicated statistically significant.

RESULTS

Calpain-2 was differentially upregulated in metastatic PCa compared with localized PCa. Moreover, calpain-2 cleaved CRMP4 into the N-terminally fragment which promoted migration and invasion in PCa cells via nuclear translocation and activation of E2F1-mediated DNA methyltransferase 1 (DNMT1) expression. NF-κB RelA/p65 recruited DNMT1 to bind to and methylate CRMP4 promoter in which Serine276 phosphorylation of p65 was essential. Furthermore, CRMP4 exhibited anti-metastatic function via inhibiting the expression of VEGFC through Semaphorin3B-Neuropilin2 signaling.

CONCLUSION

Calpain-2 may contribute to the promoter methylation of CRMP4 to repress its transcription, leading to the metastasis of PCa via enhancing VEGFC expression.

High expression of Nectin-4 is associated with unfavorable prognosis in gastric cancer

Nectins are Ca²⁺-independent immunoglobulin-like cell adhesion molecules that belong to a family of four members that function in a number of biological cellular activities. Nectin-4 is overexpressed in several types of human cancer; however, the functional and prognostic significance of Nectin-4 in gastric cancer (GC) remains unclear. In the present study, the reverse transcription-quantitative polymerase chain reaction and tissue microarray immunohistochemical analysis were used to investigate the expression of Nectin-4 in GC as well as its function in the prognosis of patients with GC. The results indicated that mRNA and protein expression of Nectin-4 were increased in tumor tissues compared with the matched non-tumor tissues. Expression of Nectin-4 was closely associated with differentiation (P=0.004), primary tumor (P=0.001), lymph node metastasis (P<0.001) and tumor-node-metastasis (TNM) stage (P<0.001). Positive Nectin-4 expression (P=0.001) and advanced TNM stage (P<0.001) were demonstrated to be associated with overall survival time in multivariate analyses. These results suggest that Nectin-4 may serve a significant function in GC and may serve as a novel clinic pathological biomarker and therapeutic target in GC.

Nectin-4 promotes gastric cancer progression via the PI3K/AKT signaling pathway

Nectin-4, a member of the Nectin family that includes 4 Ca+-independent immunoglobulin-like cell adhesion molecules, plays a carcinogenic role in multiple cancers. However, Nectin-4 expression and its biological role in gastric cancer (GC) remain largely unknown. In this study, quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemistry were used to evaluate the expression patterns of Nectin-4 in GC specimens and cell lines. We observed that high expression of Nectin-4 in GC patients was associated with TNM stage and lymph node metastasis status, and poor prognosis. In addition, cell proliferation and cell migration assays in vitro and tumorigenicity in vivo were performed to observe the effects of up-regulation and down-regulation of Nectin-4 expression on GC cell phenotypes. In further studies, the PI3K/AKT signaling pathway was revealed to be involved in Nectin-4-mediated GC progression. These results demonstrated that Nectin-4 had a promoter effect on human GC cell growth and motility, indicating that Nectin-4 may serve as an effective therapeutic target in GC.

Decreased expression of STING predicts poor prognosis in patients with gastric cancer

STING (stimulator of interferon genes) has recently been found to play an important role in host defenses against virus and intracellular bacteria via the regulation of type-I IFN signaling and innate immunity. Chronic infection with Helicobacter pylori is identified as the strongest risk factor for gastric cancer. Thus, we aim to explore the function of STING signaling in the development of gastric cancer. Immunohistochemistry was used to detect STING expression in 217 gastric cancer patients who underwent surgical resection. STING protein expression was remarkably decreased in tumor tissues compared to non-tumor tissues, and low STING staining intensity was positively correlated with tumor size, tumor invasion depth, lymph mode metastasis, TNM stage, and reduced patients’ survival. Multivariate analysis identified STING as an independent prognostic factor, which could improve the predictive accuracy for overall survival when incorporated into TNM staging system. In vitro studies revealed that knock-down of STING promoted colony formation, viability, migration and invasion of gastric cancer cells, and also led to a defect in cytosolic DNA sensing. Besides, chronic H. pylori infection up-regulated STING expression and activated STING signaling in mice. In conclusion, STING was proposed as a novel independent prognostic factor and potential immunotherapeutic target for gastric cancer.

Calpain research for drug discovery: challenges and potential

Calpains are a family of proteases that were scientifically recognized earlier than proteasomes and caspases, but remain enigmatic. However, they are known to participate in a multitude of physiological and pathological processes, performing 'limited proteolysis' whereby they do not destroy but rather modulate the functions of their substrates. Calpains are therefore referred to as 'modulator proteases'. Multidisciplinary research on calpains has begun to elucidate their involvement in pathophysiological mechanisms. Therapeutic strategies targeting malfunctions of calpains have been developed, driven primarily by improvements in the specificity and bioavailability of calpain inhibitors. Here, we review the calpain superfamily and calpain-related disorders, and discuss emerging calpain-targeted therapeutic strategies.

Elevated Expression of Calpain-4 Predicts Poor Prognosis in Patients with Gastric Cancer after Gastrectomy

Calpain-4 belongs to the calpain family of calcium-dependent cysteine proteases, and functions as a small regulatory subunit of the calpains. Recent evidence indicates that calpain-4 plays critical roles in tumor migration and invasion. However, the roles of calpain-4 in gastric tumorigenesis remain poorly understood. Herein, we examined calpain-4 expression by immunohistochemical staining on tissue microarrays containing tumor samples of 174 gastric cancer patients between 2004 and 2008 at a single center. The Kaplan-Meier method was used to compare survival curves, and expression levels were correlated to clinicopathological factors and overall survival. Our data demonstrated that calpain-4 was generally increased in gastric cancer cell lines and primary tumor tissues. High expression of calpain-4 was positively associated with vessel invasion, lymph node metastasis, and advanced TNM (Tumor Node Metastasis) stage. Multivariate analysis identified calpain-4 as an independent prognostic factor for poor prognosis. A predictive nomogram integrating calpain-4 expression with other independent prognosticators was constructed, which generated a better prognostic value for overall survival of gastric cancer patients than a TNM staging system. In conclusion, calpain-4 could be regarded as a potential prognosis indicator for clinical outcomes in gastric cancer.