An observational study to justify and plan a future phase III randomized controlled trial of metformin in improving overall survival in patients with inoperable pancreatic cancer without liver metastases. J Cancer Res Clin Oncol. 2020;146:1369-1375. [PMID: 32157435 DOI: 10.1007/s00432-020-03177-y]

Diabetes and pancreatic cancer: Exploring the two-way traffic

Pancreatic cancer (PC) is often associated with a poor prognosis. Long-standing diabetes mellitus is considered as an important risk factor for its development. This risk can be modified by the use of certain antidiabetic medications. On the other hand, new-onset diabetes can signal towards an underlying PC in the elderly population. Recently, several attempts have been made to develop an effective clinical tool for PC screening using a combination of history of new-onset diabetes and several other clinical and biochemical markers. On the contrary, diabetes affects the survival after treatment for PC. We describe this intimate and complex two-way relationship of diabetes and PC in this review by exploring the underlying pathogenesis.

Systematic Pan-Cancer Population-Based Analysis Reveals the Incidence and Prognosis of Lung Metastases at Diagnosis

Background

Metastasis is one of the most prevalent causes of death in cancer patients and the lungs are among the organs most commonly affected by metastasis. However, analysis of the incidence and prognosis of lung metastasis (LM) based on primary cancer sites is lacking.

Methods

We enrolled cancer patients with LM from the Surveillance, Epidemiology, and End Results (SEER) database. The risk factors for LM were determined using multivariate logistics regression. Forest plots were used to compare the impact of with LM versus without LM alone among different primary caner site subgroups.

Results

Among 1,525,441 cases, 47,537 presented with LM at initial diagnosis. Multivariate logistics regression revealed that male sex, older age, later T/N stage, unmarried status, and lack of insurance were risk factors for LM. The incidence of LM was 11.91% in bone cancer and 11.19% in pancreatic cancer. In terms of the distribution of primary cancers, 19.22% of LMs originated from the colon and rectum, with 11.63% from the kidneys. The median survival for LM cases was 6 months, with the best survival in testicular cancer (19 months) and bone cancer (12 months). Patients with LM had higher hazard ratio (HR) for mortality compared to those without LM, except for those with primary cancer in the brain (P=0.09). We stratified patients by primary cancer site, and subgroup analyses showed that LM had a significant negative impact on survival. The most significant was in thyroid cancer (HR = 44.79), followed by melanoma (HR = 24.26), prostate (HR = 16.0), breast (HR = 13.46), endometrial (HR = 12.64), testicular (HR = 12.31), and kidney (HR = 11.33) cancer (all P < 0.001).

Conclusion

Patients presenting with LM had higher HR for mortality compared to those without LM, except for those with brain tumor. Clinicians should pay more attention to the occurrence of LM, especially in patients with a significantly increased HR for mortality, such as those with thyroid cancer, melanoma, and prostate cancer.

Metformin-Induced Epigenetic Toxicity in Zebrafish: Experimental and Molecular Dynamics Simulation Studies

The increased detection of many prescription drugs in aquatic environments has heightened concerns of their potential ecotoxicological effects. In this study, the effects of metformin (MEF) exposure on tissue accumulation, gene expression, and global DNA methylation (GDM) in zebrafish were investigated. The toxic mechanism of MEF exposure was simulated by molecular dynamics (MD) to reveal any conformational changes to DNA methyltransferase 1 (DNMT1). The results showed MEF accumulation in the gills, gut, and liver of zebrafish after 30 days of exposure, and the bioaccumulation capacity was in the order of gut > liver > gills. After a 30 day recovery period, MEF could still be detected in zebrafish tissues in groups exposed to MEF concentrations ≥ 10 μg/L. Moreover, the liver was the main site of GDM, and the restoration of GDM in the liver was slower than that in the gut and gills during the recovery period. Furthermore, MEF could induce the abnormal expression of CYP3A65, GSTM1, p53, and DNMT1 genes in the liver due to the formation of hydrogen bonds between MEF and the protein residues of those genes. The MD simulation allowed for the mechanistic determination of MEF-induced three-dimensional (3D) conformational changes and changes to the catalytic activity of DNMT1.

Diabetes and Pancreatic Cancer-A Dangerous Liaison Relying on Carbonyl Stress

Both type 2 (T2DM) and type 1 (T1DM) diabetes mellitus confer an increased risk of pancreatic cancer in humans. The magnitude and temporal trajectory of the risk conferred by the two forms of diabetes are similar, suggesting a common mechanism. Carbonyl stress is a hallmark of hyperglycemia and dyslipidemia, which accompanies T2DM, prediabetes, and obesity. Accumulating evidence demonstrates that diabetes promotes pancreatic ductal adenocarcinoma (PDAC) in experimental models of T2DM, a finding recently confirmed in a T1DM model. The carbonyl stress markers advanced glycation end-products (AGEs), the levels of which are increased in diabetes, were shown to markedly accelerate tumor development in a mouse model of Kras-driven PDAC. Consistently, inhibition of AGE formation by trapping their carbonyl precursors (i.e., reactive carbonyl species, RCS) prevented the PDAC-promoting effect of diabetes. Considering the growing attention on carbonyl stress in the onset and progression of several cancers, including breast, lung and colorectal cancer, this review discusses the mechanisms by which glucose and lipid imbalances induce a status of carbonyl stress, the oncogenic pathways activated by AGEs and their precursors RCS, and the potential use of carbonyl-scavenging agents and AGE inhibitors in PDAC prevention and treatment, particularly in high-risk diabetic individuals.