Hyperglycemia is associated with adverse prognosis in patients with pancreatic neuroendocrine neoplasms

Metabolic changes in neuroendocrine neoplasms

Neuroendocrine neoplasms (NENs) are a group of highly heterogeneous neoplasms originating from neuroendocrine cells with a gradually increased incidence. Metabolic change is one of the recognized markers of tumor progression, which has been extensively and systematically studied in other malignant tumors. However, metabolic change in NENs has been relatively poorly studied, and systematic reviews are lacking. We reviewed the relationship between metabolic changes and NENs from the aspects of glucose metabolism, lipid metabolism, metabolic syndrome, amino acid metabolism and metabolomics, and discussed the potential therapeutic strategies of metabolic changes for NENs.

The Warburg hypothesis and the emergence of the mitochondrial metabolic theory of cancer

Otto Warburg originally proposed that cancer arose from a two-step process. The first step involved a chronic insufficiency of mitochondrial oxidative phosphorylation (OxPhos), while the second step involved a protracted compensatory energy synthesis through lactic acid fermentation. His extensive findings showed that oxygen consumption was lower while lactate production was higher in cancerous tissues than in non-cancerous tissues. Warburg considered both oxygen consumption and extracellular lactate as accurate markers for ATP production through OxPhos and glycolysis, respectively. Warburg's hypothesis was challenged from findings showing that oxygen consumption remained high in some cancer cells despite the elevated production of lactate suggesting that OxPhos was largely unimpaired. New information indicates that neither oxygen consumption nor lactate production are accurate surrogates for quantification of ATP production in cancer cells. Warburg also did not know that a significant amount of ATP could come from glutamine-driven mitochondrial substrate level phosphorylation in the glutaminolysis pathway with succinate produced as end product, thus confounding the linkage of oxygen consumption to the origin of ATP production within mitochondria. Moreover, new information shows that cytoplasmic lipid droplets and elevated aerobic lactic acid fermentation are both biomarkers for OxPhos insufficiency. Warburg's original hypothesis can now be linked to a more complete understanding of how OxPhos insufficiency underlies dysregulated cancer cell growth. These findings can also address several questionable assumptions regarding the origin of cancer thus allowing the field to advance with more effective therapeutic strategies for a less toxic metabolic management and prevention of cancer.

Changes of CA19-9 levels and related influencing factors in patients with type 2 diabetes mellitus after antidiabetic therapy

Abnormalities of carbohydrate antigen 19 - 9 (CA19-9) are common in patients with type 2 diabetes mellitus (T2DM), and in some patients, CA19-9 returns to normal level after glycemic control. The aim of this study was to investigate the factors associated with CA19-9 levels in patients with T2DM and the associated influences on the degree of reduction of CA19-9 levels after antidiabetic therapy (AT). This study was an observational cross-sectional study. A total of 213 patients with T2DM were enrolled in this study, of whom 105 with abnormal CA19-9 and 108 with normal CA19-9. Socio-demographic information, complete blood counts, biochemical indicators, thyroid function indicators, and CA19-9 level were collected separately for each subject. Levels of glycosylated hemoglobin, type A1C (HbA1c), fasting blood glucose (FBG) were significantly higher in T2DM patients with abnormal CA19-9 compared to patients with normal CA19-9 (both FDR < 0.001). CA19-9 level was significantly and positively correlated with neutrophil/lymphocyte ratio (NLR) (r = 0.16, P = 0.02), monocyte/lymphocyte ratio (MLR) (r = 0.16, P = 0.02), and FBG (r = 0.38, P < 0.001), while significantly and negatively correlated with free triiodothyronine (FT3) (r=-0.22, P = 0.002) and albumin count (r=-0.18, P = 0.007). After AT, the degree of decrease in CA19-9 level in T2DM patients with abnormal CA19-9 was significantly positively correlated with degree of decrease in FBG (r = 0.33, P < 0.001), as well as CA19-9 level before AT (r = 0.73, P < 0.001), NLR (r = 0.20, P = 0.04), and MLR (r = 0.25, P = 0.01). In this study, we investigated the influencing factors associated with CA19-9 level and the factors influencing degree of CA19-9 reduction after AT in T2DM patients with abnormal CA19-9.

Metformin and pancreatic neuroendocrine tumors: A systematic review and meta-analysis

BACKGROUND

Most patients with advanced pancreatic neuroendocrine tumors (pNETs) die due to tumor progression. Therefore, identifying new therapies with low toxicity and good tolerability to use concomitantly with the established pNET treatment is relevant. In this perspective, metformin is emerging as a molecule of interest. Retrospective studies have described metformin, a widely used agent for the treatment of patients with type 2 diabetes mellitus (T2DM), to be effective in modulating different tumor-related events, including cancer incidence, recurrence and survival by inhibiting mTOR phosphorylation. This systematic review evaluates the role of T2DM and metformin in the insurgence and post-treatment outcomes in patients with pNET.

AIM

To systematically analyze and summarize evidence related to the diagnostic and prognostic value of T2DM and metformin for predicting the insurgence and post-treatment outcomes of pNET.

METHODS

A systematic review of the published literature was undertaken, focusing on the role of T2DM and metformin in insurgence and prognosis of pNET, measured through outcomes of tumor-free survival (TFS), overall survival and progression-free survival.

RESULTS

A total of 13 studies (5674 patients) were included in this review. Analysis of 809 pNET cases from five retrospective studies (low study heterogeneity with I² = 0%) confirms the correlation between T2DM and insurgence of pNET (OR = 2.13, 95%CI = 1.56-4.55; P < 0.001). The pooled data from 1174 pNET patients showed the correlation between T2DM and post-treatment TFS in pNET patients (hazard ratio = 1.84, 95%CI = 0.78-2.90; P < 0.001). The study heterogeneity was intermediate, with I² = 51%. A few studies limited the possibility of performing pooled analysis in the setting of metformin; therefore, results were heterogeneous, with no statistical relevance to the use of this drug in the diagnosis and prognosis of pNET.

CONCLUSION

T2DM represents a risk factor for the insurgence of pNET and is a significant predictor of poor post-treatment TFS of pNET patients. Unfortunately, a few studies with heterogeneous results limited the possibility of exploring the effect of metformin in the diagnosis and prognosis of pNET.

Tumor acidity: From hallmark of cancer to target of treatment

Tumor acidity is one of the cancer hallmarks and is associated with metabolic reprogramming and the use of glycolysis, which results in a high intracellular lactic acid concentration. Cancer cells avoid acid stress major by the activation and expression of proton and lactate transporters and exchangers and have an inverted pH gradient (extracellular and intracellular pHs are acid and alkaline, respectively). The shift in the tumor acid-base balance promotes proliferation, apoptosis avoidance, invasiveness, metastatic potential, aggressiveness, immune evasion, and treatment resistance. For example, weak-base chemotherapeutic agents may have a substantially reduced cellular uptake capacity due to "ion trapping". Lactic acid negatively affects the functions of activated effector T cells, stimulates regulatory T cells, and promotes them to express programmed cell death receptor 1. On the other hand, the inversion of pH gradient could be a cancer weakness that will allow the development of new promising therapies, such as tumor-targeted pH-sensitive antibodies and pH-responsible nanoparticle conjugates with anticancer drugs. The regulation of tumor pH levels by pharmacological inhibition of pH-responsible proteins (monocarboxylate transporters, H+-ATPase, etc.) and lactate dehydrogenase A is also a promising anticancer strategy. Another idea is the oral or parenteral use of buffer systems, such as sodium bicarbonate, to neutralize tumor acidity. Buffering therapy does not counteract standard treatment methods and can be used in combination to increase effectiveness. However, the mechanisms of the anticancer effect of buffering therapy are still unclear, and more research is needed. We have attempted to summarize the basic knowledge about tumor acidity.