Nicotine enhances mesangial cell proliferation and fibronectin production in high glucose milieu via activation of Wnt/β-catenin pathway

GCF2 mediates nicotine-induced cancer stemness and progression in hepatocellular carcinoma

Cigarette smoking is one of the most impactful behavior-related risk factors for multiple cancers including hepatocellular carcinoma (HCC). Nicotine, as the principal component of tobacco, is not only responsible for smoking addiction but also a carcinogen; nevertheless, the underlying mechanisms remain unclear. Here we report that nicotine enhances HCC cancer stemness and malignant progression by upregulating the expression of GC-rich binding factor 2 (GCF2), a gene that was revealed to be upregulated in HCC and whose upregulation predicts poor prognosis, and subsequently activating the Wnt/ꞵ-catenin/SOX2 signaling pathway. We found that nicotine significantly increased GCF2 expression and that silencing of GCF2 reduced nicotine-induced cancer stemness and progression. Mechanistically, nicotine could stabilize the protein level of GCF2, and then GCF2 could robustly activate its downstream Wnt/β-catenin signaling pathway. Taken together, our results thus suggest that GCF2 is a potential target for a therapeutic strategy against nicotine-promoted HCC.

Tenascin-C promotes the proliferation and fibrosis of mesangial cells in diabetic nephropathy through the β-catenin pathway

OBJECTIVE

To mechanistically assess the involvement of tenascin-C (TNC) in diabetic nephropathy (DN).

METHODS

Renal specimens from DN patients were histopathologically examined, and their TNC expression patterns were evaluated via immunohistochemistry. Additionally, the hereditarily diabetic C57BL/KsJ db/db mice were induced to develop DN via adaptive feeding, and then their renal levels of TNC and β-catenin were assessed via western blotting and immunohistochemistry. Furthermore, the TNC and β-catenin levels in primary rat mesangial cells (RMCs) cultured with high glucose levels were assessed via western blotting. In parallel, RMCs cultured with TNC in the presence or absence of the β-catenin blocker ICG-001 were analyzed for their fibronectin and collagen I levels via immunostaining, and for their fibronectin, α-SMA, vimentin, PDGFR-β, PCNA, and β-catenin levels via western blotting.

RESULTS

The TNC levels in the specimens were associated with the pathological classification. In these DN specimens, TNC protein was highly detected in the MCs and slightly in the tubulointerstitium. Renal TNC (P < 0.05) and β-catenin (P < 0.001) were upregulated in db/db vs. db/m mice. High-glucose treatment upregulated TNC (P < 0.01) and β-catenin (P < 0.05) in RMCs. TNC treatment upregulated fibronectin (P < 0.05), α-SMA (P < 0.01), vimentin (P < 0.05), PCNA (P < 0.05), and β-catenin (P < 0.05) in RMCs, as assessed via western blotting. Immunohistochemical analysis confirmed the fibronectin upregulation and showed collagen I upregulation. Western-blot results also showed that levels of fibronectin (P < 0.001), α-SMA (P < 0.01), vimentin (P < 0.001), PCNA (P < 0.05), PDGFR-β (P < 0.05), and β-catenin (P < 0.01) were lower in RMCs co-treated with TNC and ICG-001 than in TNC-treated cells. Immunofluorescence analysis confirmed the decreased fibronectin level and showed that the collagen I level was also decreased by ICG-001.

CONCLUSION

TNC is upregulated in DN and induces MC proliferation and fibrosis through the β-catenin pathway.

Nicotine exacerbates diabetic nephropathy through upregulation of Grem1 expression

BACKGROUND

Diabetic nephropathy (DN) is a major complication of diabetes mellitus. Clinical reports indicate that smoking is a significant risk factor for chronic kidney disease, and the tobacco epidemic exacerbates kidney damage in patients with DN. However, the underlying molecular mechanisms remain unclear.

METHOD

In the present study, we used a diabetic mouse model to investigate the molecular mechanisms for nicotine-exacerbated DN. Twelve-week-old female mice were injected with streptozotocin (STZ) to establish a hyperglycemic diabetic model. After four months, the control and hyperglycemic diabetic mice were further divided into four groups (control, nicotine, diabetic mellitus, nicotine + diabetic mellitus) by intraperitoneal injection of nicotine or PBS. After two months, urine and blood were collected for kidney injury assay, and renal tissues were harvested for further molecular assays using RNA-seq analysis, real-time PCR, Western blot, and immunohistochemistry. In vitro studies, we used siRNA to suppress Grem1 expression in human podocytes. Then we treated them with nicotine and high glucose to compare podocyte injury.

RESULT

Nicotine administration alone did not cause apparent kidney injury, but it significantly increased hyperglycemia-induced albuminuria, BUN, plasma creatinine, and the kidney tissue mRNA expression of KIM-1 and NGAL. Results from RNA-seq analysis, real-time PCR, Western blot, and immunohistochemistry analysis revealed that, compared to hyperglycemia or nicotine alone, the combination of nicotine treatment and hyperglycemia significantly increased the expression of Grem1 and worsened DN. In vitro experiments, suppression of Grem1 expression attenuated nicotine-exacerbated podocyte injury.

CONCLUSION

Grem1 plays a vital role in nicotine-exacerbated DN. Grem1 may be a potential therapeutic target for chronic smokers with DN.

Xenobiotics Delivered by Electronic Nicotine Delivery Systems: Potential Cellular and Molecular Mechanisms on the Pathogenesis of Chronic Kidney Disease

Chronic kidney disease (CKD) is characterized as sustained damage to the renal parenchyma, leading to impaired renal functions and gradually progressing to end-stage renal disease (ESRD). Diabetes mellitus (DM) and arterial hypertension (AH) are underlying diseases of CKD. Genetic background, lifestyle, and xenobiotic exposures can favor CKD onset and trigger its underlying diseases. Cigarette smoking (CS) is a known modified risk factor for CKD. Compounds from tobacco combustion act through multi-mediated mechanisms that impair renal function. Electronic nicotine delivery systems (ENDS) consumption, such as e-cigarettes and heated tobacco devices, is growing worldwide. ENDS release mainly nicotine, humectants, and flavorings, which generate several byproducts when heated, including volatile organic compounds and ultrafine particles. The toxicity assessment of these products is emerging in human and experimental studies, but data are yet incipient to achieve truthful conclusions about their safety. To build up the knowledge about the effect of currently employed ENDS on the pathogenesis of CKD, cellular and molecular mechanisms of ENDS xenobiotic on DM, AH, and kidney functions were reviewed. Unraveling the toxic mechanisms of action and endpoints of ENDS exposures will contribute to the risk assessment and implementation of proper health and regulatory interventions.

Nicotine exposure of male mice protects offspring against carbon tetrachloride-induced acute liver injury

Paternal nicotine exposure can cause a phenotypic change in offspring. To study whether paternal nicotine exposure influences acute liver injury and repair of the offspring, we established a paternal nicotine exposure model in mice and treated the offspring mice with carbon tetrachloride (CCl₄ ) to induce acute liver injury. After the treatment of CCl₄ , the levels of alanine aminotransferase and aspartate aminotransferase in offspring serum of paternal nicotine exposed mice are about 37.44%, and 30.21% lower than the control mice, respectively. Transcription profiling screen and bioinformatics analysis of differently expressed genes in F1 mice liver revealed that the Wnt pathway was altered. The results demonstrate that nicotine exposure in male mice could enhance the activation of the Wnt pathway in F1 mice liver. The Wnt pathway facilitates cell proliferation and tissue repair. In conclusion, our findings showed that nicotine exposure of male mice protects hepatic against CCl₄ -induced acute injury in offspring by activating the Wnt pathway in the F1 liver.

miR-181a-5p regulates the proliferation and apoptosis of glomerular mesangial cells by targeting KLF6

Diabetic nephropathy (DN) is a chronic loss of kidney function that frequently occurs in patients with diabetes mellitus and is characterized by abnormal glomerular mesangial cell (GMC) proliferation and apoptosis. By using microarray analysis, microRNA (miR)-181a-5p has previously been identified to be dysregulated in DN. The present study aimed to determine the underlying molecular mechanisms and function of miR-181a-5p in GMCs under DN conditions. First, reverse transcription-quantitative PCR was performed to detect miR-181a-5p and kruppel-like factor 6 (KLF6) expression in GMCs following high-glucose treatment. Subsequently, MTT and flow cytometric assays were performed in order to determine the effect of miR-181a-5p and KLF6 on high-glucose-driven GMC proliferation and apoptosis. After confirming that KLF6 was a target gene of miR-181a-5p via a bioinformatics analysis and luciferase reporter assay, the mRNA and protein expression levels of associated factors in different treatment groups were measured. The results demonstrated that miR-181a-5p was significantly downregulated, while KLF6 was significantly upregulated in GMCs following treatment with high glucose. Furthermore, overexpression of miR-181a led to suppression of cell proliferation and promoted apoptosis of GMCs induced by high glucose, while these effects were inhibited by co-transfection with KLF6. Finally, miR-181-5p was demonstrated to inhibit the expression of KLF6, Bcl-2, Wnt1 and β-catenin, while increasing the expression levels of Bax and caspase-3. In conclusion, the expression levels of miR-181a-5p were downregulated in GMCs following treatment with high glucose and overexpression of miR-181a-5p may inhibit GMC proliferation and promote apoptosis, at least partially through targeting KLF6 via the Wnt/β-catenin signaling pathway. Overall, the results of the present study suggest that miR-181a-5p may have a crucial role in the occurrence and development of DN and may be a valuable diagnostic marker and therapeutic target for DN.

COX-2-derived prostaglandins as mediators of the deleterious effects of nicotine in chronic kidney disease

Tobacco smoking has been identified as a risk factor in the progression of chronic kidney disease (CKD). In previous studies, we showed that nicotine induces cyclooxygenase (COX)-2 expression in vivo and in vitro and that the administration of nicotine in vivo worsens the severity of renal injury in a model of subtotal renal ablation. In the present study, we tested the role of COX-2-derived prostaglandins on the deleterious effects of nicotine in CKD. Sham and 5/6 nephrectomy (5/6Nx) rats received tap water or nicotine (100 μg/mL) in the drinking water for 12 wk. Additional groups also systemically received the COX-2 inhibitor NS-398 (1.5 mg·kg^-1·day^-1 via osmotic minipump). The administration of nicotine worsened renal injury and proteinuria in 5/6Nx rats and increased proteinuria in sham rats. 5/6Nx rats had increased cortical production of the prostaglandins PGE₂, PGI₂, PGD₂, and PGF_2α and of thromboxane A₂. In these rats, nicotine reduced the production of all prostaglandins examined except thromboxane A₂. Treatment with the COX-2 inhibitor NS-398 resulted in complete inhibition of all prostaglandins studied and ameliorated renal injury and proteinuria in 5/6Nx rats on nicotine but not in 5/6 Nx rats on tap water. Nicotine also reduced the expression of megalin in all groups examined, and this was partially prevented by COX-2 inhibition. In the present study, we showed that in CKD, nicotine worsens renal injury at least in part by producing an imbalance in the production of prostaglandins. This imbalance in the production of prostaglandins likely plays a role in the deleterious effects of smoking on the progression of CKD.

A Glimpse of the Mechanisms Related to Renal Fibrosis in Diabetic Nephropathy

Diabetic nephropathy (DN) is a common kidney disease in people with diabetes, which is also a serious microvascular complication of diabetes and the main cause of end-stage renal disease (ESRD) in developed and developing countries. Renal fibrosis is a finally pathological change in DN. Nevertheless, the relevant mechanism of cause to renal fibrosis in DN is still complex. In this review, we summarized that the role of cell growth factors, epithelial-mesenchymal transition (EMT) in the renal fibrosis of DN, we also highlighted the miRNA and inflammatory cells, such as macrophage, T lymphocyte, and mastocyte modulate the progression of DN. In addition, there are certain other mechanisms that may yet be conclusively defined. Recent studies demonstrated that some of the new signaling pathways or molecules, such as Notch, Wnt, mTOR, Epac-Rap-1 pathway, may play a pivotal role in the modulation of ECM accumulation and renal fibrosis in DN. This review aims to elucidate the mechanism of renal fibrosis in DN and has provided new insights into possible therapeutic interventions to inhibit renal fibrosis and delay the development of DN.