IRAK2-NF-κB signaling promotes glycolysis-dependent tumor growth in pancreatic cancer.

BACKGROUND: Metabolic reprogramming has emerged as a core hallmark of cancer, and cancer metabolism has long been equated with aerobic glycolysis. Moreover, hypoxia and the hypovascular tumor microenvironment (TME) are major hallmarks of pancreatic ductal adenocarcinoma (PDAC), in which glycolysis is imperative for tumor cell survival and proliferation. Here, we explored the impact of interleukin 1 receptor-associated kinase 2 (IRAK2) on the biological behavior of PDAC and investigated the underlying mechanism. METHODS: The expression pattern and clinical relevance of IRAK2 was determined in GEO, TCGA and Ren Ji datasets. Loss-of-function and gain-of-function studies were employed to investigate the cellular functions of IRAK2 in vitro and in vivo. Gene set enrichment analysis, Seahorse metabolic analysis, immunohistochemistry and Western blot were applied to reveal the underlying molecular mechanisms. RESULTS: We found that IRAK2 is highly expressed in PDAC patient samples and is related to a poor prognosis. IRAK2 knockdown led to a significant impairment of PDAC cell proliferation via an aberrant Warburg effect. Opposite results were obtained after exogenous IRAK2 overexpression. Mechanistically, we found that IRAK2 is critical for sustaining the activation of transcription factors such as those of the nuclear factor-κB (NF-κB) family, which have increasingly been recognized as crucial players in many steps of cancer initiation and progression. Treatment with maslinic acid (MA), a NF-κB inhibitor, markedly attenuated the aberrant oncological behavior of PDAC cells caused by IRAK2 overexpression. CONCLUSIONS: Our data reveal a role of IRAK2 in PDAC metabolic reprogramming. In addition, we obtained novel insights into how immune-related pathways affect PDAC progression and suggest that targeting IRAK2 may serve as a novel therapeutic approach for PDAC.

Upregulation of ASAP3 contributes to colorectal carcinogenesis and indicates poor survival outcome.

The function and clinical implication of ArfGAP with SH3 domain, ankyrin repeat, and PH domain 3 (ASAP3) in colorectal cancer (CRC) remains undefined. In the present study, we showed that the expression level of ASAP3 was dramatically increased in CRC and its upregulation was associated with American Joint Committee on Cancer stage (P < 0.001) and poor prognosis (P = 0.0022). The combination of stage and ASAP3 expression improved the prediction of survival in CRC patients. Suppression of ASAP3 inhibited cell proliferation by inducing G1 phase arrest without influencing apoptosis. ASAP3 promoted growth of colon tumors in mice with colitis, and accelerated cell invasion and migration in vitro. Increased ASAP3 was associated with activation of the nuclear factor-κB (NF-κB) canonical pathway in CRC. Upregulation of ASAP3 increased the phosphorylation and nuclear translocation of the p65 NF-κB subunit. Mechanistically, ASAP3 interacts with NF-κB essential modulator (NEMO) and could reduce the polyubiquitinylation of NEMO. Overall, ASAP3 might regulate NF-κB via binding to NEMO. ASAP3 acts as an oncogene in colonic cancer and could be a potential biomarker of colon carcinogenesis.

Biphasic regulation of autophagy by miR-96 in prostate cancer cells under hypoxia.

Autophagy favors cell survival under hypoxia, and increasing evidence revealed that microRNAs regulate autophagy. We report here hypoxia increased the expression of miR-96 in prostate cancer cells, and miR-96 stimulated autophagy by suppressing MTOR. We found that inhibition of miR-96 abolished hypoxia-induced autophagy. Paradoxically, ectopic over-expression of miR-96 to a certain threshold, also abolished the hypoxia-induced autophagy. Further studies have shown that high levels of miR-96 inhibited autophagy through suppressing ATG7, a key autophagy-associated gene. Importantly, the miR-96 expression level threshold was determined, and the effects of miR-96 on autophagy on either side of the threshold were opposite. These data demonstrate hypoxia-induced autophagy is at least partially regulated by miR-96; miR-96 can promote or inhibit autophagy by principally inhibiting MTOR or ATG7 depending on the expression levels of miR-96. Our observation might reveal a novel regulatory mode of autophagy by microRNAs under hypoxia.

Inhibition of tumor necrosis factor alpha reduces the outgrowth of hepatic micrometastasis of colorectal tumors in a mouse model of liver ischemia-reperfusion injury.

BACKGROUND: Patients with colorectal cancer (CRC) often develop liver metastases, in which case surgery is considered the only potentially curative treatment option. However, liver surgery is associated with a risk of ischemia-reperfusion (IR) injury, which is thought to promote the growth of colorectal liver metastases. The influence of IR-induced tumor necrosis factor alpha (TNF-α) elevation in the process still is unknown. To investigate the role of TNF-α in the growth of pre-existing micrometastases in the liver following IR, we used a mouse model of colorectal liver metastases. In this model, mice received IR treatment seven days after intrasplenic injections of colorectal CT26 cells. Prior to IR treatment, either TNF-α blocker Enbrel or low-dose TNF-α, which could inhibit IR-induced TNF-α elevation, was administered by intraperitoneal injection. RESULTS: Hepatic IR treatment significantly promoted CT26 tumor growth in the liver, but either Enbrel or low-dose TNF-α pretreatment reversed this trend. Further studies showed that the CT26 + IR group prominently increased the levels of ALT and AST, liver necrosis, inflammatory infiltration and the expressions of hepatic IL-6, MMP9 and E-selectin compared to those of CT26 group. Inhibition of TNF-α elevation remarkably attenuated the increases of these liver inflammatory damage indicators and tumor-promoting factors. CONCLUSION: These findings suggested that inhibition of TNF-α elevation delayed the IR-enhanced outgrowth of colorectal liver metastases by reducing IR-induced inflammatory damage and the formation of tumor-promoting microenvironments. Both Enbrel and low-dose TNF-α represented the potential therapeutic approaches for the protection of colorectal liver metastatic patients against IR injury-induced growth of liver micrometastases foci.

The characteristics of respiratory function and pulmonary hemodynamics in patients with portal hypertension.

OBJECTIVE: To investigate the respiratory function and pulmonary hemodynamics in patients with portal hypertension (PHT). METHODS: A total of 148 patients with PHT were divided into three groups according to Child-Pugh classification. Results of blood biochemistry test, lung function test, arterial blood gas analysis, free portal pressure (FPP) and pulmonary hemodynamics measurements of the three Child-Pugh grade groups were compared with those of the control group. RESULTS: The overall incidence of arterial hypoxemia was 27.0% in PHT patients. Arterial oxygen tension (PaO(2) ) had a significant negative correlation with FPP (r=-0.76, P<0.01) and Child-Pugh grade (r=-0.42, P<0.01), as well as a positive correlation with systemic vascular resistance (SVR, r=0.24, P=0.01). Alveolar-arterial oxygen difference (A-aDO(2) ) increased in Child-Pugh grade C group when compared with Child-Pugh grade A and B groups (P<0.05). Restrictive impairment of lung function was seen in Child-Pugh grade C group. Direct measurement of the hemodynamics in PHT patients revealed a hyperdynamic disturbance in both systemic and portal venous systems, and was illustrated in pulmonary circulation as an increase of mean pulmonary arterial pressure (MPAP) and pulmonary arterial wedged pressure (PAWP) as well as a decrease of pulmonary vascular resistance (PVR). CONCLUSIONS: High output and low resistance are the key characteristics of pulmonary circulation in PHT patients and the decrease of PVR can be detected even when liver function is still compensated.

Suppression of growth of pancreatic cancer cell and expression of vascular endothelial growth factor by gene silencing with RNA interference.

OBJECTIVE: To explore the anti-angiogenesis and tumor cell growth suppressive effects resulted from gene silencing by RNAi in BxPC-3 human pancreatic cancer cells. METHODS: The designation and transfection of vascular endothelial growth factor (VEGF)-siRNA lentivirus was carried out in vitro. Real-time PCR and western blot were conducted to measure the expression levels of VEGF mRNA and protein. Flow cytometry was employed to evaluate cell apoptosis and cell death. A lactate dehydrogenase (LDH) assay was used to assess the cytotoxicity of VEGF-siRNA. A 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to picture the cellular growth. For the in vivo study, BxPC-3 cells were injected subcutaneously into nude mice to form xenografts. The mice were divided into three groups according to the intervention used. The control group, the negative control group and the knockdown group of mice were injected with saline, an empty lentivirus vehicle and lentivirus carrying VEGF-siRNA, respectively. None of the mice died during the study. When these mice were killed, the xenografts were collected and the tumor sizes of the different groups were compared. Finally, immunohistochemistry was used to assess the VEGF expression level and microvascular density. RESULTS: After the transfection of VEGF-siRNA lentivirus, the cellular expression of VEGF mRNA decreased to 50% of the control and the VEGF protein in the BxPC-3 cells decreased to 30% of the control. Apoptosis and cell death increased after transfection of the VEGF-siRNA lentivirus. The LDH assay showed high cytotoxicity induced by VEGF-siRNA lentivirus transfection. The MTT assay showed slower cellular growth in the knockdown cells. Tumor growth suppression was observed in nude mice that had received the VEGF-siRNA lentivirus transfection, and the tumor sizes of the xenografts in this group were clearly smaller than those in other two groups. VEGF expression and microvascular density were significantly decreased. CONCLUSION: Vascular endothelial growth factor gene silencing via VEGF-siRNA can effectively inhibit the production of VEGF and exert an anti-angiogenesis and tumor cell growth suppressive effect both in vitro and in vivo.