Spontaneous regression of hepatocellular carcinoma after improving diabetes mellitus: possibly responsible for immune system

Does DPP-IV Inhibition Offer New Avenues for Therapeutic Intervention in Malignant Disease?

Simple Summary

There is growing interest in identifying the effects of antidiabetic agents on cancer risk, progression, and anti-cancer treatment due to the long-term use of these medications and the inherently increased risk of malignancies in diabetic patients. Tumor development and progression are affected by multiple mediators in the tumor microenvironment, several of which may be proteolytically modified by the multifunctional protease dipeptidyl peptidase-IV (DPP-IV, CD26). Currently, low-molecular-weight DPP-IV inhibitors (gliptins) are used in patients with type 2 diabetes based on the observation that DPP-IV inhibition enhances insulin secretion by increasing the bioavailability of incretins. However, the DPP-IV-mediated cleavage of other biopeptides and chemokines is also prevented by gliptins. The potential utility of gliptins in other areas of medicine, including cancer, is therefore being evaluated. Here, we critically review the existing evidence on the role of DPP-IV inhibitors in cancer pathogenesis, their potential to be used in anti-cancer treatment, and the possible perils associated with this approach.

Abstract

Dipeptidyl peptidase IV (DPP-IV, CD26) is frequently dysregulated in cancer and plays an important role in regulating multiple bioactive peptides with the potential to influence cancer progression and the recruitment of immune cells. Therefore, it represents a potential contributing factor to cancer pathogenesis and an attractive therapeutic target. Specific DPP-IV inhibitors (gliptins) are currently used in patients with type 2 diabetes mellitus to promote insulin secretion by prolonging the activity of the incretins glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). Nevertheless, the modulation of the bioavailability and function of other DPP-IV substrates, including chemokines, raises the possibility that the use of these orally administered drugs with favorable side-effect profiles might be extended beyond the treatment of hyperglycemia. In this review, we critically examine the possible utilization of DPP-IV inhibition in cancer prevention and various aspects of cancer treatment and discuss the potential perils associated with the inhibition of DPP-IV in cancer. The current literature is summarized regarding the possible chemopreventive and cytotoxic effects of gliptins and their potential utility in modulating the anti-tumor immune response, enhancing hematopoietic stem cell transplantation, preventing acute graft-versus-host disease, and alleviating the side-effects of conventional anti-tumor treatments.

Discovery of tight-binding competitive inhibitors of dipeptidyl peptidase IV

Dipeptidyl peptidase IV (DPP-IV, EC 3.4.14.5) is an abundant serine aminopeptidase that preferentially cleaves N-terminal Xaa-Pro or Xaa-Ala dipeptides from oligopeptides. Inhibitors of DPP-IV activity are used for treating type 2 diabetes mellitus and other diseases. DPP-IV is also involved in tumor progression. We identified four new non-peptide tight-binding competitive inhibitors of porcine DPP-IV by virtual screening and enzymatic assays. Molecular docking simulations supported the competitive behavior, and the selectivity of one of the compounds in the DPP-IV family. Since three of these inhibitors are also aminopeptidase N (APN) inhibitors, we tested their impact on APN+/DPP-IV+ and DPP-IV+ human tumor cells' viability. Using kinetic assays, we determined that HL-60 tumor cells express both APN and DPP-IV activities and that MDA-MB-231 tumor cells express DPP-IV activity. The inhibitors had a slight inhibitory effect on human HEK-293 cell viability but reduced the viability of APN+/DPP-IV+ and DPP-IV+ human tumor cells more potently. Remarkably, the intraperitoneal injection of these compounds inhibited DPP-IV activity in rat brain, liver, and pancreas. In silico studies suggested inhibitors binding to serum albumin contribute to blood-brain barrier crossing. The spectrum of action of some of these compounds may be useful for niche applications.

Dipeptidyl peptidase-4 inhibitors may accelerate cirrhosis decompensation in patients with diabetes and liver cirrhosis: a nationwide population-based cohort study in Taiwan

BACKGROUND/PURPOSE

Management of type 2 diabetes mellitus (T2DM) in patients with liver cirrhosis is complex and suboptimal, but no clinical trial has adequately investigated antidiabetic drug use for such patients. We evaluate the risk of mortality, cardiovascular events, and hepatic outcomes between dipeptidyl peptidase-4 (DPP-4) inhibitor users and nonusers in patients with type 2 diabetes mellitus (T2DM) and cirrhosis.

METHODS

We selected 2828 paired propensity score matched DPP-4 inhibitor users and nonusers from a cohort of T2DM with compensated liver cirrhosis between January 1, 2007, and December 31, 2012. Cox proportional hazards models were used to assess the risk of main outcomes for DPP-4 inhibitor users.

RESULTS

The incidence rate of decompensated cirrhosis during follow-up was 2.20 and 1.53 per 100 patient-years (adjusted hazard ratio [aHR] 1.35, 95% confidence interval [CI] 1.03-1.77) for DPP-4 inhibitor users and nonusers, respectively. The aHRs (95% CI) of variceal bleeding and hepatic failure were 1.67 (1.11-2.52) and 1.35 (1.02-1.79), respectively, for DPP-4 inhibitor users over nonusers. The risk of all-cause mortality, hepatocellular carcinoma, and major cardiovascular events between DPP-4 inhibitor users and nonusers were not statistically different.

CONCLUSIONS

This study found that DPP-4 inhibitor users were associated with higher risks of decompensated cirrhosis and hepatic failure than did nonusers among patients with T2DM and compensated liver cirrhosis. We must continue to search for appropriate antidiabetic drugs for patients with liver cirrhosis.

Soluble cluster of differentiation 26/soluble dipeptidyl peptidase-4 and glypican-3 are promising serum biomarkers for the early detection of Hepatitis C virus related hepatocellular carcinoma in Egyptians

BACKGROUND AND STUDY AIMS

Many patients are diagnosed with hepatocellular carcinoma (HCC) in the late stage when it is already untreatable. Therefore, there is an increased need for sensitive biomarkers to detect HCC at an earlier stage in high risk patients with hepatitis C virus (HCV)-induced cirrhosis. This study aimed to evaluate the diagnostic performance of soluble cluster of differentiation 26/dipeptidyl peptidase 4 (sCD26/sDPP4) and glypican-3 (GPC3) as serum biomarkers for the early detection of HCV related HCC and compare it with that of the conventional tumor marker serum alpha fetoprotein (AFP).

PATIENTS AND METHODS

The study included 80 participants, 30 patients diagnosed with HCV infection without HCC (HCV group), 30 patients diagnosed with HCV- related HCC (HCV group), and 20 healthy volunteers (control group). The serum levels of GPC3 and sCD26 were measured using specific enzyme linked immunosorbant assay (ELISA) kits, whereas AFP levels were determined using chemiluminescence.

RESULTS

The serum levels of both sCD26 and GPC3 were found to be significantly higher in patients with early-stage HCC than in the HCV group, (1450 and 1.16 ng/mL, respectively). sCD26 at a cutoff value of > 1000 ng/ml, showed a high sensitivity (83.3%) and 63.3% specificity with an area under curve (AUC) of 0.811 and a 95% confidence interval (CI) of (0.682-0.94). While, the combination of GPC3 and sCD26 exhibited the best diagnostic performance for early-stage-HCC because it increased the sensitivity and specificity (85% and 93.3% respectively), with an AUC of 0.986 and a 95% CI of (0.899-1.00) compared to sCD26 alone.

CONCLUSION

We conclude that serum sCD26 could be a sensitive biomarker for the early detection of HCC among HCV patients. Moreover, the combination of sCD26 and GPC3 increases both the sensitivity and specificity for the early detection of HCV related HCC compared with AFP and could help in the monitoring of HCC in high risk patients with HCV induced cirrhosis.

Spontaneous Regression of Hepatocellular Carcinoma and Review of Reports in the Published English Literature

Background

Spontaneous regression of hepatocellular carcinoma (HCC) is a rare event, although it has been described by numerous groups. The long-term fate of individuals experiencing an SR is not well described, and the underlying mechanism(s) of SR are unknown. Case Presentation: A 79-year-old Asian female with metastatic HCC taking only valsartan for hypertension had a marked reduction in tumor dimension in the primary tumor and the pulmonary metastases. Serum alpha-fetoprotein (AFP) decreased from 17,833 μg/L to 26 μg/L. Her disease progressed after 71 months, and she died shortly after. In a review of 66 patients with SR reported in the English literature, median survival was 83 months. Median survival in 37 cases that underwent resection after SR was 108 months.

Conclusions

The case and a review of the literature illustrate that SR is often durable and associated with an excellent prognosis. Understanding the underlying mechanism of SR may point to novel therapeutic strategies.

Sitagliptin and oral cancer risk in type 2 diabetes patients

The reimbursement database of the Taiwan’s National Health Insurance was used to evaluate oral cancer risk after sitagliptin use. Patients newly diagnosed of type 2 diabetes during 1999–2008 were recruited. A 1:1 propensity score matched-pair sample of 39195 ever users and 39195 never users were followed up until December 31, 2011. Cox regression incorporated with the inverse probability of treatment weighting using propensity score was used to estimate hazard ratios. Results showed that the overall hazard ratio was not statistically significant (0.956, 95% confidence interval: 0.652–1.401). However, in tertile analyses, the hazard ratio for the first (< 7.47 months), second (7.47–15.63 months) and third (> 15.63 months) tertile of cumulative duration was 1.563 (0.963–2.537), 1.236 (0.738–2.071) and 0.345 (0.164–0.725), respectively; and was 1.575 (0.963–2.575), 1.224 (0.738–2.033) and 0.347 (0.165–0.731), respectively, for the first (< 19,600 mg), second (19,600–42,200 mg) and third (> 42,200 mg) tertile of cumulative dose. Sensitivity analyses after excluding patients who developed any other cancer during follow-up did not change the results substantially. Additionally, the risk of oral diseases that may predispose to oral cancer (i.e., “gingival and periodontal diseases" and/or "oral mucosal lesions") paralleled the risk pattern of oral cancer, suggesting a possible explanation for the risk change of oral cancer related to sitagliptin. In conclusion, sitagliptin may reduce oral cancer risk when the cumulative duration is > 15.63 months or the cumulative dose is > 42,200 mg.

DPP-4 inhibitors in diabetic complications: role of DPP-4 beyond glucose control

Dipeptidyl peptidase-4 (DPP-4) inhibitors (gliptins) are an emerging class of antidiabetic drugs that constitutes approximately fifty percent of the market share of the oral hypoglycemic drugs. Its mechanism of action for lowering blood glucose is essentially via inhibition of the rapid degradation of incretin hormones, such as glucagon-like peptide (GLP)-1 and gastric inhibitory polypeptide (GIP), thus the plasma concentration of GLP-1 increases, which promotes insulin secretion from the pancreatic β cells and suppresses glucagon secretion from the α cells. In addition to the direct actions on the pancreas, GLP-1 exhibits diverse actions on different tissues through its action on GLP-1 receptor, which is expressed ubiquitously. Moreover, DPP-4 has multiple substrates besides GLP-1 and GIP, including cytokines, chemokines, neuropeptides, and growth factors, which are involved in many pathophysiological conditions. Recently, it was suggested that DPP-4 is a new adipokine secreted from the adipose tissue, which plays an important role in the regulation of the endocrine function in obesity-associated type 2 diabetes. Consequently, DPP-4 inhibitors have been reported to exhibit cytoprotective functions against various diabetic complications affecting the liver, heart, kidneys, retina, and neurons. This review outlines the current understanding of the effect of DPP-4 inhibitors on the complications associated with type 2 diabetes, such as liver steatosis and inflammation, dysfunction of the adipose tissue and pancreas, cardiovascular diseases, nephropathy, and neuropathy in preclinical and clinical studies.