Trophoblast expression dynamics of the tumor suppressor gene gastrokine 2

Promising protein biomarkers for early gastric cancer: clinical performance of combined detection

OBJECTIVES

In the early stage of gastric cancer (GC), identifying cancer-specific biomarkers is a key step in the disease screening process. This study aims to explore the clinical value of five novel protein biomarkers and their combination (5 MP) for GC early diagnosis.

METHODS

The candidate biomarkers were mined from TCGA, GTEx, and CPTAC databases. The clinical value of the five biomarkers and 5 MP in the early diagnosis from healthy control, benign gastric disease (BGD), precancerous lesions (PLGC), early GC (EGC), and GC was evaluated by receiver operator characteristic curve (ROC), the area under the curve (AUC), sensitivity, specificity, and accuracy.

RESULTS

Five candidate biomarkers, COL10A1, GKN1, GKN2, LIPF, and REG4, were mined from TCGA, GTEx, and CPTAC databases. In the training cohort, the five proteins were confirmed to be differentially expressed in the serum of control, BGD, EGC, and GC. COL10A1 has the highest AUC of a single protein in control vs. EGC (0.857). GKN2 has the highest AUC of a single protein in BGD vs. EGC (0.822). 5 MP has an AUC of 0.890 in Control vs. EGC, and 0.854 in BGD vs. EGC. In the validation cohort, 5 MP has an AUC of 0.834 in PLGC vs. GC, and 0.839 in PLGC vs. EGC.

CONCLUSIONS

Our findings suggest that COL10A1, GKN1, GKN2, LIPF, and REG4 are useful non-invasive serum biomarkers for GC diagnosis. Combination detection (5 MP) has enhanced early diagnosis of GC and distinguishing between benign and malignant gastric diseases.

Low-level gastrokine 2 promoted progress of NSCLC and as a potential biomarker

Background

Gastrokine 2 (GKN2) is significantly downregulated in non‐small cell lung cancer (NSCLC) tissues than in normal tissues (NT), as assessed by mRNA microassay; however, the mechanism and clinical value of GKN2 is unknown in NSCLC.

Methods

A total of 60 NSCLC samples and corresponding NT samples were prospectively collected GKN2 expression in NSCLC tissues was estimated. Also, the expression level of GKN2 promoter methylation and correlation with clinical data in NSCLC patients from public databases were analyzed. Cytology experiments were also carried out.

Results

The GKN2 mRNA and protein expression level in NSCLC was significantly lower than that in the NT, and the GKN2 expression level in large tumors NSCLC was significantly lower than that in the small tumor group. Public data showed that expression of GKN2 in LUAD with P53 mutation group was lower than that of the P53 non‐mutation group, and GKN2 promoter methylation level of LUAD was significantly higher than its NT and close to age and clinical stage. Cell migration, invasion, and proliferation ability of GKN2 overexpressed were lower in A549 and PC9 groups than those in GKN2 overexpressed A549 and PC9 negative control groups, while the percentage of apoptotic cells increased in the GKN2 overexpressed A549 and PC9 groups. The DNMT3B mRNA expression levels were higher in PC9 and A549 cells than BEAS‐2B cells.

Conclusion

The overexpression of GKN2 significantly inhibited cell proliferation, migration, and invasion and promoted apoptosis. Low‐level GKN2 promoted the progression of NSCLC via DNMT3B and is expected to be a biomarker for NSCLC.

Impact of Spatially Heterogeneous Trop-2 Expression on Prognosis in Oral Squamous Cell Carcinoma

Oral cancer often presents with aggressive behavior and a high risk of recurrence and metastasis. For oral squamous cell carcinoma (OSCC), which is the most frequent histological subtype, therapy strategies include surgery, radiation therapy, chemotherapy, immune checkpoint inhibitors, and EGFR inhibitors. Recently, a Trop-2 antibody-drug conjugate (ADC) has been approved in the United States of America for the treatment of advanced triple-negative breast cancer. However, this ADC has also been tested in other solid tumors including head & neck squamous cell carcinoma. The prognostic impact of Trop-2 has already been reported for several cancers. We studied the prognostic influence of Trop-2 protein expression on OSCC patients' survival. The cohort comprised n = 229 OSCC patients with available archived tumor tissue and corresponding non-neoplastic oral mucosa tissue. Using immunohistochemistry, we investigated Trop-2 expression in both the central and peripheral regions of each tumor and in corresponding non-neoplastic oral mucosa. In patients suffering from OSCC with combined high central and low peripheral Trop-2 expression, five-year overall survival (OS) was 41.2%, whereas 55.6% of OSCC patients who presented lower central and/or higher peripheral tumoral Trop-2 expression were alive after five years (p = 0.075). In multivariate Cox regression, the expression pattern of high central tumoral and lower peripheral Trop-2 expression was significantly correlated with impaired OS (HR = 1.802, 95%-CI: 1.134-2.864; p = 0.013) and recurrence-free survival (RFS) (HR = 1.633, 95%-CI: 1.042-2.560; p = 0.033), respectively, when adjusting for co-variables. Hence, Trop-2 may serve as an independent prognostic biomarker in OSCC. In subsequent studies, the pathophysiological meaning of downregulated Trop-2 expression in the OSCC periphery has to be analyzed.

Gastrokine 2 Regulates the Antitumor Effect of JAK2/STAT3 Pathway in Gastric Cancer

GKN2 (gastrokine 2) mainly plays a regulatory role in gastric mucosal defense and cell protection mechanisms, and its role in gastric cancer has not been thoroughly elucidated. Immunohistochemistry was used to detect GKN2 and TFF1 expressions in 90 gastric cancer tissues, 48 neoplastic resection margins, and 22 normal gastric mucosa epithelia. It showed that the downregulation of GKN2 and TFF1 expressions in gastric cancer tissues was significantly different from that in adjacent normal gastric tissues and distal gastric mucosal tissues. Nevertheless, correlation analysis showed that GKN2 expression in gastric cancer tissues was independent of TFF1 expression. After overexpression of GKN2 was constructed in human gastric cancer cell line MKN28 with the Ad-GFP-GKN2 transfected, cell viability was measured by CCK-8 assay, and migration and invasion ability were analyzed by transwell migration assay and transwell invasion assay. It indicated that overexpression of GKN2 significantly reduced the viability of MKN28 and SGC7901 cells. Overexpression of GKN2 could also inhibit the migration and invasion ability in MKN28 and SGC7901 cells. In addition, upregulation of GKN2 can inactivate the JAK2/STAT3 pathway. Our data suggest that GKN2 and TFF1 play the antitumor role in gastric carcinoma, and TFF1 may not interact or cooperate with GKN2. GKN2 overexpression can inhibit the growth and metastasis by downregulating the JAK2/STAT3 pathway in gastric cancer cells.

The Rodent-Specific MicroRNA Cluster within the Sfmbt2 Gene Is Imprinted and Essential for Placental Development

MicroRNAs (miRNAs) represent small noncoding RNAs that are involved in physiological and developmental processes by posttranscriptionally inhibiting gene expression. One of the largest miRNA clusters in mice is located in intron 10 of the Sfmbt2 gene, containing 72 miRNA precursor sequences. In this study, we generated mice lacking the entire Sfmbt2 miRNA cluster to elucidate its functions during development. The Sfmbt2 miRNAs were expressed predominantly from the paternal allele in the placenta, as is the host Sfmbt2 gene. Loss of the paternal allele resulted in severely impaired development of the placenta, especially the spongiotrophoblast layer, and frequent lethality or defects of fetuses. The predicted target sequences of the miRNAs and gene expression analysis defined at least nine putative target genes, which function as tumor suppressors or apoptosis inducers. Our study has provided experimental evidence for the indispensable roles of placental miRNAs in trophoblast proliferation and thus fetal development.

Integrin α8 Is Abundant in Human, Rat, and Mouse Trophoblasts

OBJECTIVE

Integrins exert regulatory functions in placentogenesis. Null mutation of certain integrin α subunits leads to placental defects with subsequent fetal growth restriction or embryonic lethality in mice. So far, the placental role of α8 integrin remains to be determined.

METHODS

Localization of α8 integrin and its ligands, fibronectin (FN) and osteopontin (OPN), was studied by immunohistochemistry in human, rat, and mouse placenta. The vascularization of the placental labyrinth layer of α8 integrin-deficient mice was determined by CD31 staining. In humans, α8 integrin expression was assessed via real-time polymerase chain reaction in healthy placentas, in the placental pathologies such as intrauterine growth restriction (IUGR), preeclampsia, and HELLP-syndrome (hemolysis, elevated liver enzymes, low platelet count), as well as in primary extravillous trophoblasts (EVT) and villous trophoblasts.

RESULTS

In humans, α8 integrin was detected in first and third trimester syncytiotrophoblast and EVT. Although OPN showed the same localization, FN was observed in EVT only. No expressional changes in α8 integrin were detected in the placental pathologies studied. Rodent placenta showed α8 integrin expression in giant cells and in the labyrinth layer. The localization of OPN and FN, however, showed species-specific differences. Knockout of α8 integrin in mice did not cause IUGR, despite some reduction in labyrinth layer vascularization.

CONCLUSION

α8 Integrin is expressed in functional placental compartments among its ligands, OPN and/or FN, across species. Although this may point to a regulatory role in trophoblast function, our data from α8 integrin-deficient mice indicated only mild placental pathology. Thus, the lack of placental α8 integrin seems to be largely compensated for.