PCSK9 modulates the Wnt/beta-catenin signaling pathway in myocardial ischemia/reperfusion injury

Background

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a protein that affects cholesterol homeostasis. Recent research has found that PCSK9 has various effects on the heart that are unrelated to LDL cholesterol regulation. The Wnt/β-catenin signaling pathway plays a crucial role during heart development, and it is re-activated in response to cardiac injury. Low-density lipoprotein receptor-related proteins 5 (LRP5) act as co-receptors of Wnt ligands and are indispensable for Wnt/β-catenin signal transduction. However, it is not fully elucidated whether other members of the LDLR-superfamily may be targets of PCSK9.

Purpose

This study aimed to determine if LRP5 is a PCSK9 target, study the association between PCSK9 and Wnt/β-catenin signaling, and elucidate its effect on myocardial infarction in patients with ischemic cardiomyopathy.

Methods

The expression of Lrp5, phospho-β-catenin, total β-catenin was evaluated by western blot analysis, and the effects of overexpressed PCSK9 were tested under normoxia, hypoxia, or hypoxia/re-oxygenation (H/R) in mouse cardiomyocytes (HL-1). The transcriptional activity of β-catenin was assessed using the TOP-Flash/FOP-Flash luciferase reporter assay. In addition, the impact on various downstream targets of the Wnt/β-catenin signaling pathway was assessed using a quantitative real-time polymerase chain reaction. To examine whether PCSK9 regulates injury of cardiomyocytes in vivo, we subjected transgenic mice with cardiac-specific overexpression of PCSK9 (PCSK9 TG) and wild-type (WT) mice to either sham surgery or ischemia/reperfusion (I/R) surgery.

Results

Under hypoxic conditions, the Wnt/β-catenin signaling pathway-related genes were downregulated in HL-1 cells, as evidenced by lower Lrp5 and active phospho-β-catenin expression levels (0.5-fold, n=3, p<0.01). After H/R, the Wnt/β-catenin-related genes were recovered (1.5-fold, p<0.01) in the control group but not in the PCSK9 overexpressed group. In the luciferase reporter assay results, PCSK9 overexpression inhibited the recovery of β-catenin transcriptional activity after H/R, in contrast to the control group. Furthermore, mRNA levels of Axin2, Cyclin D1, which are the Wnt/β-catenin signaling downstream pathway targets, were down-regulated under hypoxia and recovered after H/R but did not recover in PCSK9 overexpressed cells. In the mouse I/R model, the overall protein levels of the Wnt/β-catenin signaling-related genes were down-regulated in PCSK9 TG mice compared to WT mice after I/R injury.

Conclusions

These results indicated that the regulation of PCSK9 is closely associated with the Wnt/β-catenin signaling pathway which may play a crucial role in damaged cardiomyocytes. It suggests that the regulation of PCSK9 could be a therapeutic target in patients with ischemic cardiomyopathy.

Funding Acknowledgement

Type of funding sources: None.

PAUF functions in the metastasis of human pancreatic cancer cells and upregulates CXCR4 expression

Pancreatic cancer is characterized by early metastatic spread, but the process of tumor cell dissemination is largely unknown. In this study we show that the soluble protein pancreatic adenocarcinoma upregulated factor (PAUF) has an important role in the metastasis and progression of the disease. Variations in the level of PAUF, either by overexpression or knockdown, resulted in altered migration, invasion and proliferation capacity of pancreatic cancer cells. Moreover, depletion of PAUF in metastatic cells dramatically abrogated the spread of the cells to distant organs in an orthotopic xenograft mouse model. PAUF elicited the activation of the extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and AKT intracellular signaling cascades and consequently their downstream transcription factors in an autocrine manner. Genome-wide expression analysis revealed that C-X-C chemokine receptor type 4 (CXCR4) expression was induced by PAUF overexpression but was repressed by PAUF knockdown. The PAUF-mediated increase in cancer cell motility was attenuated by the CXCR4 inhibitor, AMD3100, or by anti-CXCR4 antibody. Furthermore, immunohistochemical analysis of pancreatic tumor tissues clearly showed a significant positive correlation between PAUF and CXCR4 expression. Collectively, these findings indicate that PAUF enhances the metastatic potential of pancreatic cancer cells, at least in part, by upregulating CXCR4 expression.

Rapid appearance of new cerebral microbleeds after acute ischemic stroke

BACKGROUND

It is unknown whether the development of cerebral microbleeds (MBs), small areas of signal loss on T2*-weighted gradient-echo imaging (GRE), follows a slow or a rapid process. We hypothesized that MBs may develop rapidly after certain critical events, such as strokes, and investigated the frequency, location, and factors associated with the formation of new MBs after acute ischemic stroke.

METHODS

We retrospectively examined 237 consecutive acute ischemic stroke patients who underwent MRI within 24 hours and follow-up MRI during the week after symptom onset. We defined new MBs as MBs that newly appeared on follow-up GRE outside the infarcted area. We examined the association of new MBs with demographics, risk factors, laboratory data, baseline MBs, and small vessel disease (SVD; leukoaraiosis and lacunar infarctions).

RESULTS

Seventy-five patients (31.6%) had baseline MBs, and 30 (12.7%) developed new MBs. Multiple logistic regression analysis indicated that the presence of baseline MBs (odds ratio [OR] 5.72, 95% confidence interval [CI] 2.12-15.42, p = 0.001) and severe SVD (OR 2.94, 95% CI 1.12-7.77, p = 0.03) independently predicted the development of new MBs. Of the 56 new MBs, 29 (51.8%) appeared in the lobar location, 17 (30.4%) appeared in the deep location, and 10 (17.9%) appeared in the infratentorial location.

CONCLUSIONS

This study suggests that new microbleeds (MBs) can develop rapidly after acute ischemic stroke. Baseline MBs and severe small vessel disease are predictors for the development of new MBs. Further studies will be needed to investigate the clinical implications and mechanisms of these findings.

Phase II study of capecitabine and irinotecan combination chemotherapy in patients with advanced gastric cancer

The present study was conducted to evaluate the efficacy and safety of a combination regimen of capecitabine plus irinotecan in patients with advanced gastric cancer. Patients with previously untreated metastatic or recurrent, measurable gastric cancer received oral capecitabine 1000 mg m⁻² twice daily from day 1 to 14 and intravenous irinotecan 100 mg m⁻² on days 1 and 8, based on a 3-week cycle. Forty-one patients were enrolled in the current study, among whom 38 were assessable for efficacy and 40 assessable for toxicity. Three complete responses and 16 partial responses were confirmed, giving an overall response rate of 46.3%. At a median follow-up of 269 days, the median time to progression and overall survival were 5.1 and 8.6 months, respectively. Grade 3/4 neutropenia occurred in four patients and grade 3 febrile neutropenia was observed in two patients. Grade 3 diarrhoea and grade 2 hand–foot syndrome occurred in six patients and eight patients, respectively. The combination of capecitabine and irinotecan was found to be well tolerated and effective in patients with advanced gastric cancer. Accordingly, this regimen can be regarded as one of first-line treatment options for advanced gastric cancer.

Protective role of interleukin-10 promoter gene polymorphism in the pathogenesis of invasive pulmonary aspergillosis after allogeneic stem cell transplantation

The current study attempted to evaluate the association between the IL-10 promoter gene single nucleotide polymorphism (SNP) and invasive pulmonary aspergillosis (IPA) after allogeneic stem cell transplantation (SCT) in 105 patients. Three single-nucleotide polymorphisms were investigated in the proximal region of the IL-10 promoter gene (-1082/-819/-592). Two haplotypes (1082*A/819*T/592*A [ATA] and 1082*A/819*C/592*C [ACC]) were found in the current study. The overall incidence of IPA was estimated as 14.1+/-4.5% with a median onset at 186 days post-transplant (62 approximately 405 days). An increased occurrence of IPA was noted dependent on the IL-10 haplotype (0% vs 11.5+/-6.4% vs 19.7+/-7.7% for ACC/ACC vs ATA/ACC vs ATA/ATA haplotype, P=0.0307 when comparing ACC with non-ACC haplotype). In a multivariate survival analysis using Cox's proportional hazard model, the IL-10 promoter gene SNPs were identified as an independent predictive factor for the development of IPA (P=0.012, hazard ratio (HR) 9.3), along with an histocompatibility leukocyte antigen (HLA)-identical donor (P=0.005, HR 16.3), the CD34+ cell dose transplanted (P=0.004, HR 26.5), and time-dependent chronic graft-versus-host disease (GVHD; P=0.049, HR 16.0). The IL-10 ACC haplotype was found to have an apparent protective role in the development of IPA after allogeneic transplantation, regardless of HLA-disparity or chronic GVHD.

Phase II study of concurrent chemoradiotherapy with capecitabine and cisplatin in patients with locally advanced squamous cell carcinoma of the head and neck

We aimed to evaluate the efficacy and safety of concurrent chemoradiotherapy with capecitabine and cisplatin in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN). In total, 37 patients with stage III or IV SCCHN were enrolled on the study. The chemotherapy consisted of two cycles of intravenous cisplatin of 80 mg m⁻² on day 1 and oral capecitabine 825 mg m⁻² twice daily from day 1 to day 14 at 3-week intervals. The radiotherapy (1.8–2.0 Gy 1 fraction day⁻¹ to a total dose of 70–70.2 Gy) was delivered to the primary tumour site and neck. The primary tumour sites were as follows: oral cavity (n=6), oropharynx (n=11), hypopharynx (n=8), larynx (n=3), nasopharynx (n=6), and paranasal sinus (n=3). After the chemoradiotherapy, 29 complete responses (78.4%) and 6 partial responses (16.2%) were confirmed. Grade 3 or 4 neutropenia occurred only in two patients, plus grade 3 febrile neutropenia was observed only in one patient. At a median follow-up duration of 19.8 months, the estimated overall survival and progression-free survival rate at 2-year was 76.8 and 57.9%, respectively. Concurrent chemoradiotherapy with capecitabine and cisplatin was found to be well tolerated and effective in patients with locally advanced SCCHN.

Prognostic significance of platelet recovery pattern after allogeneic HLA-identical sibling transplantation and its association with severe acute GVHD

Thrombocytopenia (TP) is a frequent complication after allogeneic stem cell transplantation (SCT) and regarded as a poor prognostic factor when assessed beyond day 100. However, little is known about the clinical significance of the platelet recovery pattern before chronic graft-versus-host disease (GVHD) develops. Eighty-five patients undergoing HLA-identical sibling SCT were stratified according to their platelet recovery pattern between day +30 and +90 and the transplant outcomes analyzed, along with the association of each component of the acute GVHD grading system. Fifteen patients (18%) were classified with persistent TP, 33 patients (39%) with unstable TP, and 37 patients (43%) as non-TP. Persistent TP, which was strongly associated with severe acute GVHD (P<0.001), exhibited the worst 2-year OS (P<0.0001) and highest NRM (P<0.0001) and opportunistic infection rates (P<0.0001). In multivariate analyses, the platelet recovery pattern was identified as an independent prognostic factor (P=0.02) together with the disease risk (P=0.02) in terms of OS, and the only independent prognostic factor in terms of NRM (P=0.005) and the incidence of infectious events (P<0.001). Persistent TP was strongly associated with the development of extensive chronic GVHD (P=0.03). The platelet recovery pattern between day +30 and +90 can be used to predict the prognosis of SCT recipients.