CD26 as a Promising Biomarker for Predicting Prognosis in Patients with Pancreatic Tumors

Ugonin P inhibits lung cancer motility by suppressing DPP-4 expression via promoting the synthesis of miR-130b-5p

Lung cancer is the leading cause of cancer-related death worldwide, and the survival rate of metastatic lung cancer is exceedingly low. Helminthostatchys Zeylanica (H. Zeylanica) is a Chinese herbal medicine renowned for its anti-inflammatory, immunomodulatory, and anti-cancer activities in various cellular and animal studies. The current study evaluated the effects of H. Zeylanica derivatives on lung cancer cells. We determined that dipeptidyl peptidase-4 (DPP-4) expression levels were higher in lung cancer tissues than in normal tissues. We also determined that DPP-4 expression levels were higher in the metastatic stage and strongly correlated with lung cancer survival rates. An H. Zeylanica derivative (ugonin P) was shown to inhibit DPP-4 mRNA and protein expression in two lung cancer cell lines in a dose-dependent manner. Ugonin P was shown to decrease migration and invasion activities in lung cancer cells while promoting the synthesis of miR-130b-5p, which was found to negatively regulate DPP-4 protein expression and cell motility in lung cancer. We determined that ugonin P suppresses the DPP-4-dependent migration and invasion of lung cancer cells by downregulating the RAF/MEK/ERK signalling pathway and enhancing the expression of miR-130b-5p. This study provides compelling evidence that ugonin P could be used to develop novel therapeutic agents for the treatment of lung cancer.

Soluble DPP4 can act as a diagnostic biomarker in Hashimoto's thyroiditis with thyroid papillary carcinoma

Background

Hashimoto's thyroiditis (HT) is an independent risk factor for papillary thyroid carcinoma (PTC), but the underlying mechanism remains unknown. The incidence of PTC in patients with HT is significantly elevated, and the presence of both HT and PTC contributes to a higher rate of misdiagnosis.

Materials and Methods

Gene ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed on the thyroid nodule gene chip dataset from GEO Datasets. Serum and clinical data from 191 patients with thyroid nodules at the affiliated hospital were collected for analysis. Experimental techniques, including real-time quantitative PCR, ELISA, immunohistochemistry (IHC), and enzyme activity detection, were used to measure the level of dipeptidyl peptidase 4 (DPP4) in thyroid nodule tissues and serum.

Results

Thyroid nodules in patients with HT and PTC exhibit high levels of DPP4, along with elevated concentrations of soluble DPP4 in the serum. These findings demonstrate the potential predictive value of soluble DPP4 for PTC diagnosis.

Conclusions

The concentration and enzymatic activity of soluble DPP4 in serum can serve as diagnostic biomarkers for patients with HT-associated PTC.

The Role of Serum CD26 in the Diagnosis of Gastric Cancer

Purpose

The value of serum cluster of differentiation 26 (CD26) in gastric cancer remains unknown. We investigated serum CD26 as a non-invasive serological marker for the diagnosis of gastric cancer and its relationship with serum human epidermal growth factor receptor-2 (HER2) levels.

Patients and Methods

We enrolled 393 gastric cancer patients treated with endoscopic resection or surgery, and 90 healthy controls. HER2 positivity in tissue was evaluated by immunohistochemistry staining, and the serum CD26 and HER2 levels were measured using an enzyme-linked immunosorbent assay.

Results

Serum CD26 levels were significantly lower in gastric cancer patients than in healthy controls (582.2 ± 254.3 vs 862.7 ± 410.6 ng/mL, P<0.001). Serum CD26 levels were significantly lower in advanced gastric cancer compared to early gastric cancer (642.2 ± 333.9 vs 503.4 ± 332.7 ng/mL, P<0.001), and tended to decrease with gastric cancer progression. To diagnose gastric cancer, the optimal cut-off value of serum CD26 was 762.7 ng/mL with 75.6% sensitivity and 64.4% specificity. Serum CD26 levels were weakly correlated with serum HER2 levels (rs=0.363, P<0.001). However, no difference in serum CD26 levels was observed between tissue HER2-negative and HER2-positive gastric cancer groups (586.2 ± 362.1 vs 579.6 ± 264.8 ng/mL, P=0.898).

Conclusion

CD26 is a useful non-invasive serological marker for gastric cancer diagnosis; however, its levels do not correlate with HER2 status.

DPP4 Is a Potential Prognostic Marker of Thyroid Carcinoma and a Target for Immunotherapy

DPP4 (dipeptidyl peptidase 4) is expressed in many cancers, but the relationship between DPP4 and thyroid carcinoma (THCA) is incompletely understood. We aim to explore the expression of DPP4 in THCA and the correlation between DPP4 expression with the prognosis of THCA and antitumor immunity. We systematically analyzed data from The Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), and Gene Expression Omnibus (GEO) databases and explored DPP4 expression, its impact on prognosis, and its relationship with antitumor immunity in THCA. Next, we collected 18 pairs of fresh THCA and adjacent paracancerous tissues and performed RT-qPCR to validate the DPP4 mRNA level. Concurrently, immunohistochemistry (IHC) analysis was performed on 12 pairs of paraffin-embedded tissues of medullary thyroid carcinoma (MTC) and paracancerous tissues to validate the DPP4 protein level. Bioinformatics analysis showed that DPP4 mRNA expression in THCA was significantly higher than that in paracancerous tissues (p < 0.01). DPP4 was expressed at the highest levels in MTC than in other pathological types. The DPP4 expression level was different between groups with different clinical characteristics. The higher the DPP4 expressed in THCA, the lower the disease-free survival (DFS) was (HR = 1.8, p=0.048). DPP4 was significantly correlated with immune cell infiltration and immune response and was positively associated with 21 immune checkpoint genes (ICGs) in THCA (p < 0.05). The results of RT-qPCR showed that the relative mRNA expression of DPP4 was significantly upregulated in 18 THCA tissues compared to that in paracancerous tissues (p=0.011). IHC results showed that the DPP4 protein level was higher in 12 MTC tissues than in paracancerous tissues (p=0.011). In conclusion, DPP4 is a potential prognostic marker of THCA and may become an effective target for immunotherapy.

CD26/DPP-4: Type 2 Diabetes Drug Target with Potential Influence on Cancer Biology

Simple Summary

Dipeptidyl peptidase (DPP)-4 inhibitor is widely used for type 2 diabetes. Although DPP-4/CD26 has been recognized as both a suppressor and inducer in tumor biology due to its various functions, how DPP-4 inhibitor affects cancer progression in diabetic patients is still unknown. The aim of this review is to summarize one unfavorable aspect of DPP-4 inhibitor in cancer-bearing diabetic patients.

Abstract

DPP-4/CD26, a membrane-bound glycoprotein, is ubiquitously expressed and has diverse biological functions. Because of its enzymatic action, such as the degradation of incretin hormones, DPP-4/CD26 is recognized as the significant therapeutic target for type 2 diabetes (T2DM); DPP-4 inhibitors have been used as an anti-diabetic agent for a decade. The safety profile of DPP-4 inhibitors for a cardiovascular event in T2DM patients has been widely analyzed; however, a clear association between DPP-4 inhibitors and tumor biology is not yet established. Previous preclinical studies reported that DPP-4 suppression would impact tumor progression processes. With regard to this finding, we have shown that the DPP-4 inhibitor induces breast cancer metastasis and chemoresistance via an increase in its substrate C-X-C motif chemokine 12, and the consequent induction of epithelial-mesenchymal transition in the tumor. DPP-4/CD26 plays diverse pivotal roles beyond blood glucose control; thus, DPP-4 inhibitors can potentially impact cancer-bearing T2DM patients either favorably or unfavorably. In this review, we primarily focus on the possible undesirable effect of DPP-4 inhibition on tumor biology. Clinicians should note that the safety of DPP-4 inhibitors for diabetic patients with an existing cancer is an unresolved issue, and further mechanistic analysis is essential in this field.