Liprin-α1 contributes to oncogenic MAPK signaling by counteracting ERK activity

PTPRF interacting protein alpha 1 (PPFIA1) encodes for liprin-α1, a member of the leukocyte common antigen-related protein tyrosine phosphatase (LAR-RPTPs)-interacting protein family. Liprin-α1 localizes to adhesive and invasive structures in the periphery of cancer cells, where it modulates migration and invasion in head and neck squamous cell carcinoma (HNSCC) and breast cancer. To study the possible role of liprin-α1 in anticancer drug responses, we screened a library of oncology compounds in cell lines with high endogenous PPFIA1 expression. The compounds with the highest differential responses between high PPFIA1-expressing and silenced cells across cell lines were inhibitors targeting mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinases (ERK) signaling. KRAS proto-oncogene, GTPase (KRAS)-mutated MDA-MB-231 cells were more resistant to trametinib upon PPFIA1 knockdown compared with control cells. In contrast, liprin-α1-depleted HNSCC cells with low RAS activity showed a context-dependent response to MEK/ERK inhibitors. Importantly, we showed that liprin-α1 depletion leads to increased p-ERK1/2 levels in all our studied cell lines independent of KRAS mutational status, suggesting a role of liprin-α1 in the regulation of MAPK oncogenic signaling. Furthermore, liprin-α1 depletion led to more pronounced redistribution of RAS proteins to the cell membrane. Our data suggest that liprin-α1 is an important contributor to oncogenic RAS/MAPK signaling, and the status of liprin-α1 may assist in predicting drug responses in cancer cells in a context-dependent manner.

Combined tumor-directed recruitment and protection from immune suppression enable CAR T cell efficacy in solid tumors

CAR T cell therapy remains ineffective in solid tumors, due largely to poor infiltration and T cell suppression at the tumor site. T regulatory (Treg) cells suppress the immune response via inhibitory factors such as transforming growth factor-β (TGF-β). Treg cells expressing the C-C chemokine receptor 8 (CCR8) have been associated with poor prognosis in solid tumors. We postulated that CCR8 could be exploited to redirect effector T cells to the tumor site while a dominant-negative TGF-β receptor 2 (DNR) can simultaneously shield them from TGF-β. We identified that CCL1 from activated T cells potentiates a feedback loop for CCR8+ T cell recruitment to the tumor site. This sustained and improved infiltration of engineered T cells synergized with TGF-β shielding for improved therapeutic efficacy. Our results demonstrate that addition of CCR8 and DNR into CAR T cells can render them effective in solid tumors.

The common SLC30A8 Arg325Trp variant is associated with reduced first-phase insulin release in 846 non-diabetic offspring of type 2 diabetes patients--the EUGENE2 study

AIMS/HYPOTHESIS

A recent genome-wide association study identified the SLC30A8 rs13266634 polymorphism encoding an Arg325Trp polymorphism in the zinc transporter protein member 8 (ZnT-8) to be associated with type 2 diabetes. Here, we investigate whether the polymorphism is related to altered insulin release in response to intravenous and oral glucose loads in non-diabetic offspring of type 2 diabetic patients.

METHODS

We genotyped SLC30A8 rs13266634 in 846 non-diabetic offspring of type 2 diabetic patients from five different white populations: Danish (n = 271), Finnish (n = 217), German (n = 149), Italian (n = 109) and Swedish (n = 100). Participants were subjected to both IVGTTs and OGTTs, and measurements of insulin sensitivity.

RESULTS

Homozygous carriers of the major type 2 diabetes C risk-allele showed a 19% decrease in first-phase insulin release (0-10 min) measured during the IVGTT (CC 3,624 +/- 3,197; CT 3,763 +/- 2,674; TT 4,478 +/- 3,032 pmol l(-1) min(-1), mean +/- SD; p = 0.007). We found no significant genotype effect on insulin release measured during the OGTT or on estimates of insulin sensitivity.

CONCLUSIONS/INTERPRETATION

Of European non-diabetic offspring of type 2 diabetes patients, 46% are homozygous carriers of the Arg325Trp polymorphism in ZnT-8, which is known to associate with type 2 diabetes. These diabetes-prone offspring are characterised by a 19% decrease in first-phase insulin release following an intravenous glucose load, suggesting a role for this variant in the pathogenesis of pancreatic beta cell dysfunction.

Insulin sensitivity, insulin release and glucagon-like peptide-1 levels in persons with impaired fasting glucose and/or impaired glucose tolerance in the EUGENE2 study

AIMS/HYPOTHESIS

We examined the phenotype of individuals with impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) with regard to insulin release and insulin resistance.

METHODS

Non-diabetic offspring (n=874; mean age 40+/-10.4 years; BMI 26.6+/-4.9 kg/m(2)) of type 2 diabetic patients from five different European Centres (Denmark, Finland, Germany, Italy and Sweden) were examined with regard to insulin sensitivity (euglycaemic clamps), insulin release (IVGTT) and glucose tolerance (OGTT). The levels of glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) were measured during the OGTT in 278 individuals.

RESULTS

Normal glucose tolerance was found in 634 participants, while 110 had isolated IFG, 86 had isolated IGT and 44 had both IFG and IGT, i.e. about 28% had a form of reduced glucose tolerance. Participants with isolated IFG had lower glucose-corrected first-phase (0-10 min) and higher second-phase insulin release (10-60 min) during the IVGTT, while insulin sensitivity was reduced in all groups with abnormal glucose tolerance. Similarly, GLP-1 but not GIP levels were reduced in individuals with abnormal glucose tolerance.

CONCLUSIONS/INTERPRETATION

The primary mechanism leading to hyperglycaemia in participants with isolated IFG is likely to be impaired basal and first-phase insulin secretion, whereas in isolated IGT the primary mechanism leading to postglucose load hyperglycaemia is insulin resistance. Reduced GLP-1 levels were seen in all groups with abnormal glucose tolerance and were unrelated to the insulin release pattern during an IVGTT.

Variants of transcription factor 7-like 2 (TCF7L2) gene predict conversion to type 2 diabetes in the Finnish Diabetes Prevention Study and are associated with impaired glucose regulation and impaired insulin secretion

AIMS/HYPOTHESIS

We investigated the association of variants of the transcription factor 7-like 2 (TCF7L2) gene with: (1) incident diabetes in the Finnish Diabetes Prevention Study (DPS, Study I); (2) type 2 diabetes and impaired glucose regulation (i.e. IGT or IFG) in a cross-sectional study (Study II); and (3) insulin secretion, insulin sensitivity and adipose tissue expression of TCF7L2 in offspring of type 2 diabetic probands (III).

SUBJECTS AND METHODS

Study I (the DPS) included 507 individuals with IGT who were randomly allocated to control and intervention groups and followed for an average of 3.9 years to monitor for progression to diabetes. Study II was a population-based cross-sectional study of 1,766 men, aged 50-70 years, randomly selected from the population of Kuopio, eastern Finland. Study III included 238 non-diabetic offspring of patients with type 2 diabetes. Genotyping of rs12255372 and rs7903146 of TCF7L2 was carried out.

RESULTS

In the DPS, the TT genotype of rs12255372 was significantly associated with an adjusted 2.85-fold risk (95% CI 1.17-6.95, p = 0.021) of incident diabetes in the control group, but not in the intervention group. In Study II, the adjusted odds ratio in subjects with the TT genotype was 3.40 (1.45-7.97, p = 0.005) for the comparison of diabetic subjects with normoglycaemic subjects. The T allele of rs12255372 was significantly associated with decreased insulin secretion (Studies II, III). Expression of TCF7L2 in adipose tissue tended to be lower in subjects with the TT risk genotypes of rs12255372 and rs7903146.

CONCLUSIONS/INTERPRETATION

The variant of rs12255372 of TCF7L2 was associated with incident type 2 diabetes in the DPS and in a separate population-based cross-sectional study. Impaired insulin secretion is likely to be the main cause for our findings.

Common polymorphisms of calpain-10 are associated with abdominal obesity in subjects at high risk of type 2 diabetes

AIMS/HYPOTHESIS

The mechanisms by which the calpain-10 gene (CAPN10) affects the risk of type 2 diabetes are unclear. Therefore, we investigated the effects of four polymorphisms in CAPN10 (single nucleotide polymorphism [SNP]-43, SNP-44, Insertion/Deletion [Indel]-19 and SNP-63) on insulin secretion, insulin action and abdominal fat distribution in offspring of patients with type 2 diabetes.

SUBJECTS AND METHODS

Insulin secretion was determined by an IVGTT, insulin action by the hyperinsulinaemic-euglycaemic clamp and abdominal fat distribution by computed tomography in 158 non-diabetic offspring (age 34.9+/-6.3 years [mean+/-SD], BMI 26.2+/-4.9 kg/m(2)) of type 2 diabetic patients.

RESULTS

SNP-43 (p=0.009 over the three genotypes, adjusted for age, sex, BMI and family relationship) and haplotypes carrying the A allele of SNP-43 were associated with intra-abdominal fat area. The A allele of SNP-43 was associated with intra-abdominal fat area in men (p=0.014) but not in women. SNP-44, InDel-19 and SNP-63 were not associated with intra-abdominal fat area or insulin action. Furthermore, we demonstrated in a separate sample of middle-aged men (n=234) who had a history of type 2 diabetes in first-degree relatives that the A allele of SNP-43 was associated with a large waist circumference, and high insulin levels in an OGTT.

CONCLUSIONS/INTERPRETATION

SNP-43 of CAPN10 may contribute to the risk of diabetes by regulating abdominal obesity in subjects with high risk of type 2 diabetes.

High amount of visceral fat mass is associated with multiple metabolic changes in offspring of type 2 diabetic patients

OBJECTIVE

To investigate the relative contribution of total body fat mass (TFM) and intra-abdominal fat mass (IAFM) to metabolic consequences of obesity in offspring of type 2 diabetic parents.

DESIGN

Cross-sectional study of 129 nondiabetic offspring of diabetic parents (59 men, 70 women, age 35.7 +/- 6.3 y, body mass index 26.2 +/- 4.6 kg/m2). Study subjects were grouped according to TFM (assessed with bioelectrical impedance) and IAFM (assessed with CT). Insulin sensitivity was assessed with the euglycemic hyperinsulinemic clamp, insulin secretion with the intravenous glucose tolerance test and energy expenditure with indirect calorimetry. Furthermore, C-reactive protein (CRP) and adiponectin levels were measured.

RESULTS

Insulin resistance, low rates of oxidative and nonoxidative glucose disposal, high rates of lipid oxidation and reduced energy expenditure during hyperinsulinemia were associated with high IAFM, independently of TFM. Adiponectin level was reduced and CRP level increased in subjects with high IAFM.

CONCLUSIONS

The metabolic changes relating to obesity are largely attributable to high IAFM, and are present even in normal weight subjects with high IAFM.