YTHDF2 promotes gastric cancer progression and enhances chemoradiotherapy resistance

The role of YTHDF2 in gastric cancer (GC) is controversial. Due to the limitations of technical difficulty and experimental period, research on completely knocking out YTHDF2 is rare. Therefore, further investigations are still needed to clarify the YTHDF2's clinical significance and biological function in GC. To carry out the investigation, an analysis was performed on the expression levels of YTHDF2 in both publicly available databases and samples obtained from patients with gastric cancer. Based on the complete knockout of YTHDF2 using the CRISPR-Cas9 system, in vivo and in vitro experiments were conducted to analyze the effects of YTHDF2 on tumor formation, radiotherapy and chemoradiotherapy resistance in GC. Our investigation revealed an increase in YTHDF2 levels in GC tissues, which was found to be associated with a negative prognosis. Under hypoxic conditions, high expression of YTHDF2 enhanced the invasion of gastric cancer cells, and high expression of YTHDF2 was associated with HIF-1a. YTHDF2 facilitated gastric cancer cell growth in vitro and in vivo. Moreover, the results of the present study demonstrated that YTHDF2 mediated the expression of CyclinD1 and stability of CyclinD1 mRNA. CyclinD1 knockdown inhibited YTHDF2-mediated GC cell proliferation whereas CyclinD1 overexpression ameliorated YTHDF2 knockdown-induced inhibition of GC progression. Furthermore, YTHDF2 also promoted resistance to DDP and CTX chemotherapy, along with radiotherapy treatment for GC cells. The findings suggested that YTHDF2 expression accelerated GC progression through a potential mechanism involving CyclinD1 expression, and enhanced chemoradiotherapy resistance. This indicated that YTHDF2 could be a promising prognostic biomarker and therapeutic target for individuals diagnosed with GC.

Empagliflozin and pirfenidone confer renoprotection through suppression of glycogen synthase kinase-3β and promotion of tubular regeneration in rats with induced metabolic syndrome

Metabolic syndrome (MetS) is largely coupled with chronic kidney disease (CKD). Glycogen synthase kinase-3β (GSK-3β) pathway drives tubular injury in animal models of acute kidney injury; but its contribution in CKD is still elusive. This study investigated the effect empagliflozin and/or pirfenidone against MetS-induced kidney dysfunction, and to clarify additional underpinning mechanisms particularly the GSK-3β signaling pathway. Adult male rats received 10%w/v fructose in drinking water for 20 weeks to develop MetS, then treated with either drug vehicle, empagliflozin (30 mg/kg/day) and/or pirfenidone (100 mg/kg/day) via oral gavage for subsequent 4 weeks, concurrently with the high dietary fructose. Age-matched rats receiving normal drinking water were used as controls. After 24 weeks, blood and kidneys were harvested for subsequent analyses. Rats with MetS showed signs of kidney dysfunction, structural changes and interstitial fibrosis. Activation of GSK-3β, decreased cyclinD1 expression and enhanced apoptotic signaling were found in kidneys of MetS rats. There was abundant alpha-smooth muscle actin (α-SMA) expression along with up-regulation of TGF-β1/Smad3 in kidneys of MetS rats. These derangements were almost alleviated by empagliflozin or pirfenidone, with evidence that the combined therapy was more effective than either individual drug. This study emphasizes a novel mechanism underpinning the beneficial effects of empagliflozin and pirfenidone on kidney dysfunction associated with MetS through targeting GSK-3β signaling which can mediate the regenerative capacity, anti-apoptotic effects and anti-fibrotic properties of such drugs. These findings recommend the possibility of using empagliflozin and pirfenidone as promising therapies for management of CKD in patients with MetS.

Association between COVID 19 exposure and expression of malignant pathological features in oral squamous cell carcinoma: A retrospective cohort study

OBJECTIVES

To analyze the relationship between the clinical and pathological characters of OSCC and COVID 19 exposure.

MATERIALS AND METHODS

A retrospective cohort study in patients with OSCC with or without COVID 19 was performed. A total of 200 OSCC patients treated with surgery from 2019 to 2023 were included. Clinical and pathological features were analysed between two groups. Characters with statistical difference were further analysed by performing univariate analysis and logistic regression analysis.

RESULTS

The expression of Ki67 (n = 57, 71.3 %, P < 0.001) and CyclinD1 (n = 64, 80 %, P < 0.001) in OSCC with the exposure history of COVID 19 is higher than that in patients never exposed to COVID 19. COVID 19 exposure history is an independent influencing factor for higher expression of Ki67 (OR = 4.04, 95 % CI: 1.87-8.72, P < 0.001) and CyclinD1 (OR = 5.45, 95 % CI: 2.56-11.60, P < 0.001).

CONCLUSION

COVID 19 may suggest more invasive malignant biological behavior of cancer cells in OSCC.

BMP9-ID1 Pathway Attenuates N6-Methyladenosine Levels of CyclinD1 to Promote Cell Proliferation in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a highly lethal malignant neoplasm, and the involvement of bone morphogenetic protein 9 (BMP9) has been implicated in the pathogenesis of liver diseases and HCC. Our goal was to investigate the role of BMP9 signaling in regulating N6-methyladenosine (m6A) methylation and cell cycle progression, and evaluate the therapeutic potential of BMP receptor inhibitors for HCC treatment. We observed that elevated levels of BMP9 expression in tumor tissues or serum samples from HCC patients were associated with a poorer prognosis. Through in vitro experiments utilizing the m6A dot blotting assay, we ascertained that BMP9 reduced the global RNA m6A methylation level in Huh7 and Hep3B cells, thereby facilitating their cell cycle progression. This effect was mediated by an increase in the expression of the inhibitor of DNA-binding protein 1 (ID1). Additionally, using methylated RNA immunoprecipitation qPCR(MeRIP-qPCR), we showed that the BMP9-ID1 pathway promoted CyclinD1 expression by decreasing the m6A methylation level in the 5' UTR of mRNA. This occurred through the upregulation of the fat mass and obesity-associated protein (FTO) in Huh7 and Hep3B cells. In our in vivo mouse xenograft models, we demonstrated that blocking the BMP receptor with LDN-212854 effectively suppressed HCC growth and induced global RNA m6A methylation. Overall, our findings indicate that the BMP9-ID1 pathway promotes HCC cell proliferation by down-regulating the m6A methylation level in the 5' UTR of CyclinD1 mRNA. Targeting the BMP9-ID1 pathway holds promise as a potential therapeutic strategy for treating HCC.

Chrysin Encapsulated Copper Nanoparticles with Low Dose of Gamma Radiation Elicit Tumor Cell Death Through p38 MAPK/NF-κB Pathways

Improving radiation effect on tumor cells using radiosensitizers is gaining traction for improving chemoradiotherapy. This study aimed to evaluate copper nanoparticles (CuNPs) synthesized using chrysin as radiosensitizer with γ-radiation on biochemical and histopathological approaches in mice bearing Ehrlich solid tumor. CuNPs were characterized with irregular round sharp shape with size range of 21.19-70.79 nm and plasmon absorption at 273 nm. In vitro study on MCF-7 cells detected cytotoxic effect of CuNPs with IC50 of 57.2 ± 3.1 μg. In vivo study was performed on mice transplanted with Ehrlich solid tumor (EC). Mice were injected with CuNPs (0.67 mg/kg body weight) and/or exposed to low dose of gamma radiation (0.5 Gy). EC mice exposed to combined treatment of CuNPs and radiation showed a marked reduction in tumor volume, ALT and CAT, creatinine, calcium, and GSH, along with elevation in MDA, caspase-3 in parallel with inhibition of NF-κB, p38 MAPK, and cyclin D1 gene expression. Comparing histopathological findings of treatment groups ends that combined treatment was of higher efficacy, showing tumor tissue regression and increase in apoptotic cells. In conclusion, CuNPs with a low dose of gamma radiation showed more powerful ability for tumor suppression via promoting oxidative state, stimulating apoptosis, and inhibiting proliferation pathway through p38MAPK/NF-κB and cyclinD1.

LDHA deficiency inhibits trophoblast proliferation via the PI3K/AKT/FOXO1/CyclinD1 signaling pathway in unexplained recurrent spontaneous abortion

Dysregulated trophoblast proliferation, invasion, and apoptosis may cause several pregnancy-associated complications, such as unexplained recurrent spontaneous abortion (URSA). Recent studies have shown that metabolic abnormalities, including glycolysis inhibition, may dysregulate trophoblast function, leading to URSA. However, the underlying mechanisms remain unclear. Herein, we found that lactate dehydrogenase A (LDHA), a key enzyme in glycolysis, was significantly reduced in the placental villus of URSA patients. The human trophoblast cell line HTR-8/SVneo was used to investigate the possible LDHA-mediated regulation of trophoblast function. LDHA knockdown in HTR-8/SVneo cells induced G0/G1 phase arrest and increased apoptosis, whereas LDHA overexpression reversed these effects. Next, RNA sequencing combined with Kyoto Encyclopedia of Genes and Genomes analysis demonstrated that the PI3K/AKT signaling pathway is potentially affected by downstream genes of LDHA. Especially, we found that LDHA knockdown decreased the phosphorylation levels of PI3K, AKT, and FOXO1, resulting in a significant downregulation of CyclinD1. In addition, treatment with an AKT inhibitor or FOXO1 inhibitor also verified that the PI3K/AKT/FOXO1 signaling pathway influenced the gene expression of CyclinD1 in trophoblast. Moreover, p-AKT expression correlated positively with LDHA expression in syncytiotrophoblasts and extravillous trophoblasts in first-trimester villus. Collectively, this study revealed a new regulatory pathway for LDHA/PI3K/AKT/FOXO1/CyclinD1 in the trophoblast cell cycle and proliferation.

Downstream Signaling of Inflammasome Pathway Affects Patients' Outcome in the Context of Distinct Molecular Breast Cancer Subtypes

Inflammasomes are protein complexes involved in the regulation of different biological conditions. Over the past few years, the role of NLRP3 in different tumor types has gained interest. In breast cancer (BC), NLRP3 has been associated with multiple processes including epithelia mesenchymal transition, invasion and metastization. Little is known about molecular modifications of NLRP3 up-regulation. In this study, in a cohort of BCs, the expression levels of NLRP3 and PYCARD were analyzed in combination with CyclinD1 and MYC ones and their gene alterations. We described a correlation between the NLRP3/PYCARD axis and CyclinD1 (p < 0.0001). NLRP3, PYCARD and CyclinD1’s positive expression was observed in estrogen receptor (ER) and progesterone receptor (PgR) positive cases (p < 0.0001). Furthermore, a reduction of NLRP3 and PYCARD expression has been observed in triple negative breast cancers (TNBCs) with respect to the Luminal phenotypes (p = 0.017 and p = 0.0015, respectively). The association NLRP3+/CCND1+ or PYCARD+/CCND1+ was related to more aggressive clinicopathological characteristics and a worse clinical outcome, both for progression free survival (PFS) and overall survival (OS) with respect to NLRP3+/CCND1− or PYCARD+/CCND1− patients, both in the whole cohort and also in the subset of Luminal tumors. In conclusion, our study shows that the NLRP3 inflammasome complex is down-regulated in TNBC compared to the Luminal subgroup. Moreover, the expression levels of NLRP3 and PYCARD together with the alterations of CCND1 results in Luminal subtype BC’ss poor prognosis.

Activated cell-cycle CDK4/CyclinD1-pRB-E2F1 signaling pathway is involved in the apoptosis of dorsal raphe nucleus in the rat model of PTSD

Dysregulation of the dorsal raphe nucleus (DRN) has been revealed to contribute to cognitive and arousal impairments associated with post-traumatic stress disorder (PTSD) in an animal model. In our research an acute exposure to single prolonged stress (SPS) was used to establish PTSD rat model and the effects related to cell-cycle signaling pathway in DRN were examined. Apoptosis in DRN was detected by TUNEL staining, showing that DRN apoptosis number was sharply increased after SPS. SPS triggered cell-cycle CDK4/CyclinD1-pRB-E2F1 signal pathway. Treatment with CDK4 inhibitor Abemaciclib successfully attenuated the DRN apoptosis and rescued decreased spatial learning and memory abilities in SPS rats, indicating that activation of CDK4/CyclinD1-pRB-E2F1 pathway was involved in DRN apoptosis, which may be one of the pathogenesis for PTSD.

USP5 Sustains the Proliferation of Glioblastoma Through Stabilization of CyclinD1

Glioblastoma multiforme (GBM) is one of the most malignant primary tumors in humans. Despite standard therapeutic strategy with tumor resection combined with radiochemotherapy, the prognosis remains disappointed. Recently, deubiquitinating enzymes (DUBs) has been reported as potential cancer therapy targets due to their multifunctions involved in the regulation of tumorigenesis, cell cycle, apoptosis, and autophagy. In this study, we found that knockdown of ubiquitin specific protease (USP5), a family member of DUB, could significantly suppress GBM cell line U251 and DBTRG-05MG proliferation and colony formation by inducing cell cycle G1/S arrest, which was correlated with downregulation of CyclinD1 protein level. CyclinD1 had been reported to play a critical role in the tumorigenesis and development of GBM via regulating cell cycle transition. Overexpression of USP5 could significantly extend the half-life of CyclinD1, while knockdown of USP5 decreased the protein level of CyclinD1, which could be restored by proteasome inhibitor MG-132. Indeed, USP5 was found to directly interact with CyclinD1, and decrease its K48-linked polyubiquitination level. Furthermore, knockdown of USP5 in U251 cells remarkably inhibited tumor growth in vivo. Taken together, these findings demonstrate that USP5 plays a critical role in tumorigenesis and progression of GBM by stabilizing CyclinD1 protein. Targeting USP5 could be a potential therapeutic strategy for GBM.

miR-486-3p regulates CyclinD1 and promotes fluoride-induced osteoblast proliferation and activation

Fluoride is a persistent environmental pollutant, and its excessive intake contributes to skeletal and dental fluorosis. The mechanisms underlying fluoride-induced abnormal osteoblast proliferation and activation, which are related to skeletal fluorosis, have not yet been fully clarified. As important epigenetic regulators, microRNAs (miRNAs) participate in bone metabolism. On the basis of our previous miRNA-seq results and bioinformatics analysis, this study investigated the role and specific molecular mechanism of miR-486-3p in fluoride-induced osteoblast proliferation and activation via CyclinD1. Herein, in the fluoride-challenged population, we observed that miR-486-3p expression decreased while CyclinD1 and transforming growth factor (TGF)-β1 increased, and miR-486-3p level correlated negatively with the expression of CyclinD1 and TGF-β1 genes. Further, we verified that sodium fluoride (NaF) decreases miR-486-3p expression in human osteoblasts and overexpression of miR-486-3p reduces fluoride-induced osteoblast proliferation and activation. Meanwhile, we demonstrated that miR-486-3p regulates NaF-induced upregulation of CyclinD1 by directly targeting its 3'-untranslated region (3'-UTR). In addition, we observed that NaF activates the TGF-β1/Smad2/3/CyclinD1 axis and miR-486-3p mediates transcriptional regulation of CyclinD1 by TGF-β1/Smad2/3 signaling pathway via targeting TGF-β1 3'-UTR in vitro. This study, thus, contributes significantly in revealing the mechanism of miR-486-3p-mediated CyclinD1 upregulation in skeletal fluorosis and sheds new light on endemic fluorosis treatment.

Let-7c-5p Regulates CyclinD1 in Fluoride-Mediated Osteoblast Proliferation and Activation

Endemic fluorosis is caused by the intake of high environmental fluoride, which causes dental and skeletal fluorosis. Osteoblast proliferation and activation is closely related to skeletal fluorosis and is tightly regulated by the cell cycle. Several biological processes, including bone metabolism and osteoblast proliferation and activation, are regulated by a type of noncoding RNA called microRNAs (miRNAs). However, the understanding of miRNA functions in skeletal fluorosis is limited. Based on our previous miRNA sequencing results and bioinformatics analysis, we investigated the function of the miRNA let-7c-5p to regulate CyclinD1 in fluoride-induced osteoblast proliferation and activation. We designed population experiments as well as in vitro studies using 5-Ethynyl-2'-deoxyuridine (EdU), flow cytometry, immunofluorescence, dual-luciferase reporters, and chromatin immunoprecipitation. The population-based analysis showed a decrease in let-7c-5p expression as fluoride exposure increased. In addition, let-7c-5p levels were negatively correlated with CyclinD1 and Wnt9a (another let-7c-5p target). We verified in vitro that let-7c-5p participates in the fluoride-induced proliferation and activation of human osteoblasts by directly targeting CyclinD1. Furthermore, we demonstrated that let-7c-5p regulates CyclinD1 expression via the Wnt/β-catenin signaling pathway. This study demonstrated the participation of let-7c-5p in fluoride-induced proliferation and activation of human osteoblasts by regulation of CyclinD1 expression at the post-transcriptional and transcriptional levels.

RPL22 Overexpression Promotes Psoriasis-Like Lesion by Inducing Keratinocytes Abnormal Biological Behavior

Background

Keratinocytes of psoriasis have anti-apoptotic properties including delayed apoptosis process, accelerated proliferation metabolism and postponed differentiation process. However, the specific mechanism leading to the abnormal biological behavior of keratinocytes remains unclear.

Objectives

We investigated the role of increased RPL22 expression in regulating the abnormal biological behavior of keratinocytes and the mechanism of regulation of RPL22 expression in skin lesions of psoriatic patients.

Methods

We examined clinical samples and utilized cytokine-induced cell and IMQ-treated mouse models. We determined the expression and functions of RPL22 in vitro and in vivo.

Results

We showed that RPL22 expression was significantly increased in the skin lesions of psoriasis patients and IMQ-treated psoriatic-like mice. Such increased expression is attributed to hyperacetylation of histone H3K27 in the promoter region of RPL22. Interestingly, overexpression of RPL22 enhanced keratinocyte proliferation by increasing cyclinD1 expression and accelerated CD4⁺T cells recruitment via upregulating CXCL10 expression. Finally, we demonstrated that RPL22 overexpression promoted psoriasiform phenotypes in IMQ-induced mouse skins.

Conclusions

These findings suggested that RPL22 regulates keratinocytes abnormal biological behavior and contributes to the development of psoriatic phenotypes. Thus, RPL22 might be a novel potential molecular target for treatment of psoriasis.

BAP1 promotes viability and migration of ECA109 cells through KLF5/CyclinD1/FGF-BP1

More than 40 000 patients worldwide die from esophageal cancer annually. The 5-year survival rate of patients is only ~ 15-20%, and thus, there is an ongoing need to improve diagnosis and treatment of esophageal cancer. Breast cancer type 1 susceptibility protein (BRCA1)-associated protein (BAP1) is a marker of poor prognosis in several cancers, including uveal melanoma, renal cell carcinoma, cholangiocarcinoma, non-small cell lung cancer, and colorectal cancer. BAP1 mutations are early and rare events in esophageal carcinoma, but the involvement of BAP1 in progression of esophageal carcinoma is unclear. Here, we report that cell proliferation and migration were significantly enhanced in esophageal carcinoma ECA109 cells overexpressing BAP1, while they were diminished upon BAP1 knockdown. In addition, the expression of Krüppel-like factor 5 (KLF5), CyclinD1, and FGF-BP1 was increased by BAP1 overexpression and decreased by BAP1 knockdown. Our data suggest that BAP1 promotes cell proliferation and migration, and enhances the expression of KLF5 and its downstream genes, including CyclinD1 and FGF-BP1, in the esophageal carcinoma cell line ECA109.

AKT/GSK-3β/β-catenin signaling pathway participates in erythropoietin-promoted glioma proliferation

PURPOSE

Although erythropoietin (EPO) has been proven to significantly promote the proliferation of cancer cells, the mechanism for promoting glioma proliferation is poorly understood. Here, we examined the functional role of the AKT/GSK-3β/β-catenin signaling pathway in the EPO-mediated proliferation of glioma.

METHODS

The distribution of EPO and Ki-67 among clinical samples with different WHO grades was plotted by Immunological Histological Chemistry analysis. U87 and U251 glioma cell lines were treated with short hairpin RNA targeting (shEPO), recombinant human erythropoietin (rhEPO) and/or AKT-specific inhibitor (MK-2206). The changes in phosphorylated AKT, nuclear β-catenin, cyclin D1 and p27kip1 expression were detected. Cell cycle distributions and glioma proliferation in vitro and in vivo were analyzed.

RESULTS

The expression level of EPO was significantly elevated with the increase of WHO grade and Ki67 in clinical glioma specimens. In vitro, knockdown of endogenous EPO in U87 and U251 cells effectively block the phosphorylation of AKT and GSK-3β and the expression of nuclear β-catenin. shEPO treatment also significantly decreased the expression of cyclin D1 and increased the expression of p27kip1. The cell cycle transition then slowed down and the proliferation of glioma cells or mouse xenograft tumors both decreased. Treatment of cells or tumors with extra rhEPO reversed the above biological effects mediated by shEPO. rhEPO-induced activation of the AKT/GSK-3β/β-catenin pathway and proliferation were abolished by MK-2206.

CONCLUSIONS

Our study identified the AKT/GSK-3β/β-catenin axis as a critical mediator of EPO-induced glioma proliferation and further provided a clinically significant dimension to the biology of EPO.

Cul4B promotes the progression of ovarian cancer by upregulating the expression of CDK2 and CyclinD1

Background

Ovarian cancer is one of the most common malignant tumors in the female reproductive system with the highest mortality rate. Cul4B participates in the oncogenesis and progression of several malignant tumors. However, the role of Cul4B in ovarian cancer has not been studied.

Results

High expression of intratumor Cul4B was associated with poor patient survival. Cul4B expression was associated with FIGO stage and Cul4B was independent risk factor of ovarian cancer disease-free survival and overall survival. In vitro studies revealed that overexpression of Cul4B promoted tumor proliferation while knockdown of Cul4B significantly inhibited the proliferation capacity of ovarian cancer cells. Mechanistically, Cul4B was found to promotes cell entering S phase from G0/G1 phase by regulating the expression of CDK2 and CyclinD1. Cul4B regulates the expression of CDK2 and CyclinD1 by repressing miR-372.

Conclusions

The results revealed that high expression of Cul4B is associated with poor ovarian cancer prognosis and Cul4B may serve as a potential treating target for an adjuvant therapy.

SOCS1 blocks G1-S transition in hepatocellular carcinoma by reducing the stability of the CyclinD1/CDK4 complex in the nucleus

Inhibitors of the CDK family of proteins have been approved for the treatment of a variety of tumours; however, the development of new drugs administered in combination with CDK inhibitors is expected to improve the therapeutic effect. We identified the function of suppressor of cytokine signalling 1 (SOCS1) in hepatocellular carcinoma (HCC) cell models and the xenograft mouse model. When SOCS1 expression was artificially upregulated, HCC cell lines were arrested at the G1-S transition in the cell cycle. Interestingly, during this process, total CyclinD1 protein increased, but the effective proportion decreased. We found that the deficiency of CyclinD1 in the nucleus is probably due to the decrease in the stability of nuclear CyclinD1 caused by the ubiquitin-based degradation of P21, thus inhibiting the progression of the cell cycle to S phase. After P21 expression was increased, the levels of the component that inactivates CyclinD1 decreased as expected. It showed that P21 has a partial promoting effect on cancer. SOCS1 is a good indicator of prognosis, tumour size and long-term survival after resection. SOCS1 is expected to become a drug target in combined with CDK family inhibitors.

CyclinD1 Is a New Target Gene of Tumor Suppressor MiR-520e in Breast Cancer

Objective

To investigate the involvement of miR-520e in the modulation of cancer-promoting cyclinD1 in breast cancer.

Methods

A reverse transcription-polymerase chain reaction (RT-PCR) was applied to test the regulation of miR-520e on cyclinD1. The binding of miR-520e to 3'-untranslated region (3'UTR) of cyclinD1 mRNA was predicted by an online bioinformatics website. The effect of miR-520e on the luciferase reporters with binding sites of miR-520e and 3'UTR of cyclinD1 mRNA was revealed using a luciferase reporter gene assay. The correlation between miR-520e and cyclinD1 in clinical breast cancer samples was detected through quantitative real-time PCR.

Results

The expression of cyclinD1 was gradually reduced as the dose of miR-520e increased. Anti-miR-520e obviously induced cyclinD1 in breast cancer cells. After anti-miR-520e was introduced into the cells, the inhibition of cyclinD1 expression mediated by miR-520e was reversed. The binding of miR-520e with cyclinD1 was revealed via bioinformatics. Under the treatment of dose-increasing miR-520e or anti-miR-520e, the luciferase activities of cyclinD1 3'UTR vector were lower or higher by degrees. However, the activity of the mutant vector was not affected at all. Finally, in clinical breast cancer tissues the negative correlation of miR-520e with cyclinD1 was revealed.

Conclusion

In conclusion, cyclinD1 is a new target of miR-520e in breast cancer.

Prostaglandin E2 accelerated recovery of chemotherapy-induced intestinal damage by increasing expression of cyclin D

Intestinal stem cells (ISCs) play a crucial role in maintaining intestinal homeostasis upon chemotherapy and radiotherapy. It has been documented that prostaglandin E2 (PGE2) treatment improved hematopoietic stem cell function in vitro and in vivo, while the relationship between PGE2 and intestinal stem cells remains unclear. Presently, mice were exposed to PGE1, dmPGE2 and indomethacin. Numbers and function of ISCs were assessed by analyzing Olfm4⁺ ISCs. Intestinal protection of dmPGE2 was investigated on a 5-fluorouracil (5FU)-induced intestinal damage mouse model. The results showed that dmPGE2 treatment, but not PGE1, increased numbers of Olfm4⁺ ISCs in dose- and time-dependent manners. Indomethacin treatment decreased numbers of Olfm4⁺ ISCs. The beneficial effects of short-term dmPGE2 treatment on intestine were supported in a 5FU-induced intestinal damage model. Our data showed that 5FU treatment significantly decreased numbers of Olfm4⁺ ISCs and goblet cells in intestine, which could be ameliorated by dmPGE2 treatment. dmPGE2 treatment accelerated the recovery of 5FU-induced ISC injury via increasing expression of cyclin D1 and D2 in intestine. Furthermore, dmPGE2 treatment-induced expression of cyclin D1 and D2 might be mediated by up-regulation of FOXM1 expression in intestine. These findings feature PGE2 as an effective protector against chemotherapy-induced intestinal damage.

Long noncoding RNA HULC accelerates the growth of human liver cancer stem cells by upregulating CyclinD1 through miR675-PKM2 pathway via autophagy

BACKGROUND

The functions of HULC have been demonstrated in several cancers. However, its mechanism has not been elucidated in human liver cancer stem cells.

METHODS

Liver cancer stem cells were isolated from Huh7 cells; gene infection and tumorigenesis test in vitro and in vivo were performed.

RESULTS

We demonstrate that HULC promotes growth of liver cancer stem cells in vitro and in vivo. Mechanistically, HULC enhances the expression of Sirt1 dependent on miR675 and then induces the cellular autophagy through Sirt1. HULC enhances CyclinD1 and thereby increases pRB and inhibited P21 WAF1/CIP 1 via autophagy-miR675-PKM2 pathway in human liver cancer stem cells. Ultimately, our results demonstrate that CyclinD1 is required for the oncogenic functions of HULC in liver cancer stem cells.

CONCLUSIONS

It reveals the key molecular signaling pathways for HULC and provides important basic information for finding effective tumor therapeutic targets based on HULC.

CyclinD1 inhibits dicer and crucial miRNA expression by chromatin modification to promote the progression of intrahepatic cholangiocarcinoma

Background

CyclinD1 is crucial for cell cycling and can regulate the expression of Dicer, a crucial regulator of microRNA maturation. However, little is known on how CyclinD1 regulates Dicer and miRNA expression, and the progression of intrahepatic cholangiocarcinoma (ICC).

Methods

The expression of CyclinD1 and Dicer in non-tumor cholangiocytes, ICC cells and tissues as well as their association with clinicopathological characteristics and survival were examined. The potential mechanisms by which CyclinD1 regulates Dicer and relative miRNA expression were determined by immunoprecipitation, ChIP sequence, BSP and luciferase reporter assays following induction of CyclinD1 over-expression or silencing and Dicer silencing. The impact of CyclinD1 and/or Dicer silencing on the growth of ICC was tested in vivo.

Results

Up-regulated CyclinD1 was associated with down-regulated Dicer expression in ICC tissues and poorer overall survival in patients with ICC. CyclinD1 interacted with the nuclear H3K9me3 and SUV39H1 and bound to the Dicer promoter to increase its CpG island methylation in ICC cells. Functionally, CyclinD1 silencing inhibited the malignancy of ICC cells, which were mitigated partially by Dicer silencing in ICC cells. Dicer silencing down-regulated miR-1914-5p and miR-541-5p expression, which targeted and promoted CyclinD1 and CDK6 expression in ICC cells.

Conclusions

Our findings uncover that CyclinD1 inhibits Dicer expression by chromatin modification to reduce miR-1914-5p/miR-541-5p expression, which positively-feedback enhances CyclinD1 and CDK6 expression and progression of ICC.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1415-5) contains supplementary material, which is available to authorized users.

The Regulatory Effects of CDKN1A on Relevant Genes in Kaposi's Sarcoma Cells

The cyclin-dependent kinase inhibitor 1A (CDKN1A) gene plays important roles in different types of cancer; however, its mechanism in Kaposi's Sarcoma (KS) is far less known. The aim of this study is to investigate the regulatory effects of CDKN1A on relevant genes in KS cells, and ultimately determine the role of CDKN1A in KS. In the study, the CDKN1A overexpression group, or siRNA group, was transfected into KS cells, respectively. Western-Blot (WB) and quantitative real-time polymerase chain reactions (q-PCR) were performed to detect the expression of cell cycle protein D1 (CyclinD1) and cell cycle protein E (CyclinE). Q-PCR was performed to determine the expression of kshv-mir-k12-1-5p. The results prove that CDKN1A negatively regulates the expression of CyclinD1, CyclinE, and kshv-mir-k1-2-1-5p. Therefore, CDKN1A may be involved in the formation and development of KS through the regulation of kshv-mir-k12-1-5p, CyclinD1, and CyclinE. CDKN1A may become a new choice for targeted therapy in KS.

RASSF-1A modulates proliferation-mediated oral squamous cell carcinoma progression

Background

To investigate the expression of RASSF-1A in oral squamous cell carcinoma (OSCC) and adjacent tissues, and to explore its mechanism of action in the development of OSCC.

Methods

RASSF-1A and proliferation-related protein expression in clinical and OSCC mouse models were detected by qPCR and western blot. In vitro experiments were used siRNA knockdown of RASSF-1A gene in SCC9 cells to detect cell proliferation, migration and apoptosis. In vivo experiments were performed using adenovirus overexpressing RASSF-1A gene in mice and observing tumor growth.

Results

The results of qPCR and western blot showed that the expression of RASSF-1A gene was decreased in OSCC, and the expression of CyclinD1 protein was increased. The results of co-immunoprecipitation showed that the two proteins were significantly combined in the oral cancer cell line. Knocking down the RASSF-1A gene in SCC9 cells promotes cell migration and proliferation, while reducing apoptosis and increasing CyclinD1 protein expression. Overexpression of RASSF-1A gene in mice reduces tumor volume and inhibits CyclinD1 protein expression.

Conclusions

Low expression of RASSF-1A gene in OSCC promotes the expression of CyclinD1 protein and tumor growth.

Cyclin D1 expression and novel mutational findings in Rosai-Dorfman disease

Rosai-Dorfman disease (RDD) is an enigmatic histiocytic disorder classically diagnosed by a distinctive combination of pathological features: emperipolesis, or migration of intact haematological cells through the voluminous cytoplasm of lesional histiocytes, and expression of S100 by these histiocytes. The pathogenesis has long been elusive until the recent detection of recurrent and mutually exclusive mutations in several oncogenes in the mitogen-activated protein kinase (MAPK) pathway. Based on these findings, we investigated a cohort of 21 RDD patients and found that the lesional histiocytes in 86% (18/21) of patients exhibited strong and diffuse nuclear Cyclin D1 expression, which not only may provide a diagnostic marker for this sometimes pathologically challenging disease, but also probably reflects constitutive MAPK pathway activation because we additionally identified phosphorylated-ERK expression in 90% (19/21) of cases. Further, we performed massively parallel sequencing on a subset (6/18) of the CyclinD1 positive cases, identifying several mutations that have not been previously reported in RDD. Taken together, our findings bolster the concept of RDD as a disease of MAPK activation in a substantial percentage of cases and enhance the current understanding of the pathogenesis of RDD.

Estrogen Receptor Beta (ERβ) Mediated-CyclinD1 Degradation via Autophagy Plays an Anti-Proliferation Role in Colon Cells

Dysfunction of autophagic degradation machinery causes tumorigenesis, including colorectal cancer (CRC). Overexpression of CyclinD1 in CRC has been reported. Recent evidence also suggests that ERβ deficiency is related to the pathogenesis of CRC. Very little is known, however, about the detailed molecular mechanisms underlying the relationship among ERβ, autophagy, and CyclinD1 in CRC. Here, results showed that ERβ played an anti-proliferation role in HCT116 through impairing cell cycle but not apoptosis. Additionally, CyclinD1 accumulation was increased in response to chloroquine (CQ) or in MEF Atg7 knockout cells. Further, ERβ could inhibit the mammalian target of rapamycin (mTOR) or activate Bcl-2/adenovirus E1B 19-kDa-interacting protein 3 (BNIP3) to promote autophagy in HCT116. In summary, these results indicate that ERβ-mediated CyclinD1 degradation can inhibit colon cancer cell growth via autophagy.

Approach the Invasive Potential with Hurthle Cell Tumors of Thyroid

To observe the expression of P53, CyclinD1, Ki-67, Galectin-3, COX-2, Bcl-2 and approach their contribution on assessing the invasive potential for Hurthle cell tumors. Seventy-three cases of Hurthle cell tumor were collected for immunohistochemistry staining. The patients were followed up with 8 months to 5 years. Tumors were divided into four grades according to invasion and diameter:(1) extremely low risk (27 cases that less than 2 cm and without invasion), (2) low risk (18 cases that within 2-3.9 cm and without invasion), (3) moderate risk (21 cases that achieve 4 cm and without invasion), (4) high risk (7 cases that with invasion of capsule/vessel in spite of the diameter). Immunostaining presented that all 73 cases were positive with Galectin-3, COX-2 and Bcl-2. For each group, P53 positive were 29.6%, 55.6%, 90.5%, 100.0%; CyclinD1 stained with 7.4%,22.2%,52.4%,100.0% and Ki-67 were 0.0%,5.6%,9.5%,28.6%, respectively. The higher risk of tumor, the more cases that positive expressed P53 and CyclinD1. After following up within 49 patients, two of the recurring cases were positive with P53 and CyclinD1 and one of which was also highly expressed Ki-67. Detecting P53, CyclinD1 and Ki-67 might provide reference for invasive potential assessment with Hurthle cell tumors but not Galectin-3, COX-2 and Bcl-2.

Shikonin enhances sensitization of gefitinib against wild-type EGFR non-small cell lung cancer via inhibition PKM2/stat3/cyclinD1 signal pathway

AIMS

Mutant EGFR Non-small cell lung cancer has benefit from gefitinib, but it has limited effect for wild-type EGFR tumors. Shikonin, a natural naphthoquinone isolated from a traditional Chinese medicine, the plant Lithospermum erythrorhizon (zicao), not only can inhibit the tumor growth, but also overcome cancer drug resistance. Our aim is to investigate whether shikonin can enhance antitumor effect of gefitinib in EGFR wild-type lung cancer cells in vitro and in vivo.

MATERIALS AND METHODS

CCK-8 was used to determine the proliferation of EGFR wild-type non-small cell lung cancer. Apoptosis and cell cycle were detected by flow cytometry. PKM2, STAT3, p-STAT3 and cyclinD1 were detected by Western blot. A549 tumor model was established to observe the antitumor effect of shikonin combination with gefitinib in vivo.

KEY FINDINGS

The results showed that combination of shikonin with gefitinib exhibited synergistic antitumor effect in vitro and in vivo. Its potential molecular mechanisms may be associated with inhibition of PKM2/STAT3/cyclinD1.

SIGNIFICANCE

These results provide a promising therapeutic approach for the treatment of wild-type EGFR non-small cell lung cancer.

CyclinD1 promotes lymph node metastasis by inducing lymphangiogenesis in human ovarian carcinoma

AIMS AND BACKGROUND

CyclinD1 regulates the G1/S phase transition of the cell cycle and is frequently overexpressed in many types of human cancers. Much evidence has implicated that the expression of CyclinD1 is related to the lymphatic metastasis of human ovarian carcinoma. However, the mechanism of CyclinD1 in lymphatic metastasis of ovarian carcinomas is still unclear. The objective of the present study was to assess the incidence of CyclinD1 expression in ovarian carcinomas and look for its correlation with lymph vessel density (LVD) and clinicopathological variables.

METHODS

We assessed the expression of CyclinD1 levels and lymph vessel density (LVD) quantified through D2-40 by immunohistochemistry from 110 Chinese patients with primary ovarian carcinomas and 40 with benign ovarian tumors as controls.

RESULTS

CyclinD1 was detected in 52 primary ovarian carcinomas (47.3%), which was significantly higher than its expression in the benign ovarian tumors. CyclinD1 expression was correlated with tumor grade, FIGO stage, T stage and lymphatic metastasis. Moreover, the LVD counts in the group of CyclinD1 positive expression were higher than in the group of CyclinD1 negative expression.

CONCLUSIONS

Our findings indicate that CyclinD1 might be involved in lymph node metastasis by inducing lymphangiogenesis in human ovarian carcinoma.

Suppression of cleavage factor Im 25 promotes the proliferation of lung cancer cells through alternative polyadenylation

BACKGROUND

Non-small cell lung cancer (NSCLC) is a life-threatening disease that has a poor prognosis and low survival rate. Cleavage factor Im 25 (CFIm25) is a RNA-binding protein that if down-regulated causes 3'UTR shortening and thus promotes the transcript stability of target genes. It is not clear whether CFIm25 and alternative polyadenylation (APA) play a role during cancer development. The purpose of this study is to explore the role of CFIm25 in lung cancer cell proliferation.

METHODS

CFIm25 was knocked down in A549 cells. Western blots were carried out to determine the protein expression of CFIm25, insulin growth factor 1 receptor (IGF1R), CyclinD1 (CCND1) and TP53. Real-time qRT PCR was performed to determine the total transcript levels of CFIm25 targets and the normalized fold changes in their distal PAS (dPAS) usage. Immunofluorescence was carried out to check the expression of CFIm25, IGF1R and CCND1. Cell proliferation over time was determined using the WST-1 reagent.

RESULTS

The transcript levels of CCND1 and GSK3β were significantly increased and the dPAS usage of several oncogenes (IGF1R, CCND1 and GSK3β) were decreased after CFIm25 knockdown. The protein level of IGF1R was increased, and we detected increased percentage of CCND1 positive cells and cell proliferation over time in CFIm25 knockdown cells. In addition, the mRNA and APA analysis of IGF1R using patient RNA-seq data from the Cancer Genome Atlas indicated that IGF1R is shortened in both lung adenocarcinoma and lung squamous cell carcinoma compared to normal controls.

CONCLUSIONS

Our findings suggest that CFIm25 plays an important role in lung cancer cell proliferation through regulating the APA of oncogenes, including IGF1R, and promoting their protein expression.

KIF18B promotes tumor progression through activating the Wnt/β-catenin pathway in cervical cancer

Background

KIF18B was identified as a potential oncogene by analysis of The Cancer Genome Atlas database.

Materials and methods

We assessed KIF18B expression and explored its clinical significance in cervical cancer tissues. We have also evaluated the effects of KIF18B on cervical cancer cell proliferation, migration, and invasion both in vitro and in vivo.

Results

Our results show that KIF18B is overexpressed in cervical cancer tissues and is associated with a large primary tumor size, an advanced FIGO stage, and an advanced tumor grade. Knockdown of KIF18B induces cell cycle G1-phase arrest and inhibits the proliferation, migration, and invasion of cervical cancer cells, whereas its overexpression promotes proliferation, migration, and invasion in these cells. Moreover, silencing of KIF18B reduces expression of CyclinD1, β-catenin, C-myc, and p-GSK3β expression.

Conclusion

These data suggest that KIF18B can serve as a novel oncogene that promotes the tumorigenicity of cervical cancer cells by activating Wnt/β-catenin signaling pathway.

Sphk1 promotes breast epithelial cell proliferation via NF-κB-p65-mediated cyclin D1 expression

Lipid metabolism is crucially involved with the promotion of malignant progression and metastasis in various cancers. Growing evidence suggests that many types of cancers express high levels of sphingosine kinase 1 (Sphk1), which is known to mediate cell proliferation We hypothesized that Sphk1/sphingosine-1-phosphate (S1P) signaling contributes to tumor progression. In MCF10A and MCF10A-Sphk1 breast epithelial cells, we used TNF-α to activate the Sphk1/S1P pathway and the measured expression levels of NF-κBp65 and cyclin D1 mRNA and protein in the presence and absence of an NF-κB-p65 inhibitor. Chromatin immunoprecipitation assays were performed to determine whether NF-κB-p65 binds to the cyclin D1 promoter. We found that overexpression of Sphk1 induced NF-κB-p65 activation, increased expression of cyclin D1, shortened the cell division cycle, and thus promoted proliferation of breast epithelial cells. These findings provide insight into the mechanism by which an Sphk1/NF-κB-p65/cyclin D1 signaling pathway mediates cell proliferation.

Efficacy of Shikonin against Esophageal Cancer Cells and its possible mechanisms in vitro and in vivo

Increasing evidences indicate that shikonin can suppress the tumor growth. However, the mechanisms remain elusive. In the present study, we investigated the effects and mechanisms of shikonin against esophageal cancer. The expression of hypoxia inducible factor 1α (HIF1α) and pyruvate kinase M2 (PKM2) in esophageal cancer tissues and cells was detected by immunohistochemistry and Western blot. CCK-8 was used to examine the esophageal cancer cell viability. Apoptosis and cell cycle were analyzed by flow cytometry. The expression of EGFR, PI3K, Akt, p-AKT, mTOR, HIF1α and PKM2 was detected by Western blot. EC109/pkm2 was established by lentivirus transducer. Ec109 tumor model was founded to observe the antitumor effect of shikonin in vivo. We found that HIF1α and PKM2 protein expression levels were higher in esophageal cancer tissues and cells than normal esophageal tissues and cells. Shikonin reduced esophageal cancer cells viability and induced cell cycle arrest and apoptosis. Shikonin decreased EGFR, PI3K, p-AKT, HIF1α and PKM2 expression. Overexpression of PKM2 could enhance resistance of esophageal cancer cells to shikonin. In vivo we found that shikonin reduced tumor burden, inducing cell arrest and apoptosis. Taken together, shikonin has a significant antitumor effect in the esophageal cancer by regulating HIF1α/PKM2 signal pathway.

Inhibition of the CyclinD1 promoter in response to sonic hedgehog signaling pathway transduction is mediated by Gli1

Medulloblastoma (MB) is the most common malignant tumor of the central nervous system in children. Accumulating evidence suggests a major role for the activation of the sonic hedgehog (SHH) signaling pathway in the development of MB cells; however, the mechanisms underlying the effect of this pathway on tumor survival and growth remain poorly understood. The Gli family zinc finger 1 (Gli1) transcription factor is considered as a mediator of the SHH signaling pathway in MB cells. Therefore, the present study investigated whether the SHH signaling pathway promotes the apoptosis of MB cells via downregulation of Gli1. GANT61, a novel Gli1 inhibitor, is known to have an in vitro activity against tumors. In the current study, Daoy cells were treated with different concentrations of GANT61 for 24 h, and the effect on cell proliferation was assayed by cell counting kit-8 assay. In addition, the cell cycle progression and apoptosis were assayed by flow cytometry analysis and hematoxylin-eosin (HE) staining. The effects of GANT61 treatment on SHH signaling pathway at the mRNA level were assayed by polymerase chain reaction (PCR). To further elucidate the inhibitory effects of GANT61 on the expression of Gli1 and CyclinD1, their protein levels were examined by western blot and immunofluorescence. The results indicated that GANT61 significantly inhibited the proliferation of Daoy cells in a dose-dependent manner, compared with the control group (P<0.05). HE staining revealed that cells had increasingly abnormal protuberance with increasing GANT61 concentration. Flow cytometry analysis also demonstrated that GANT61 induced G1/S arrest and apoptosis of Daoy cells in a dose-dependent manner (P<0.05). Gli1 and CyclinD1 mRNA expression levels were downregulated by GANT61 treatment (P<0.05); similarly, their protein levels were downregulated by GANT61 treatment in a dose-dependent manner (P<0.05). In conclusion, Gli1 expression was significantly associated with CyclinD1 expression in MB. These data demonstrated that Gli1 is an important mediator of the SHH pathway activity in MB, and may be a novel agent for use in combined chemotherapeutic regimens.

PGC-1α regulates the cell cycle through ATP and ROS in CH1 cells

Peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) is a transcriptional co-activator involved in mitochondrial biogenesis, respiratory capacity, and oxidative phosphorylation (OXPHOS). PGC-1α plays an important role in cellular metabolism and is associated with tumorigenesis, suggesting an involvement in cell cycle progression. However, the underlying mechanisms mediating its involvement in these processes remain unclear. To elucidate the signaling pathways involved in PGC-1α function, we established a cell line, CH1 PGC-1α, which stably overexpresses PGC-1α. Using this cell line, we found that over-expression of PGC-1α stimulated extra adenosine triphosphate (ATP) and reduced reactive oxygen species (ROS) production. These effects were accompanied by up-regulation of the cell cycle checkpoint regulators CyclinD1 and CyclinB1. We hypothesized that ATP and ROS function as cellular signals to regulate cyclins and control cell cycle progression. Indeed, we found that reduction of ATP levels down-regulated CyclinD1 but not CyclinB1, whereas elevation of ROS levels down-regulated CyclinB1 but not CyclinD1. Furthermore, both low ATP levels and elevated ROS levels inhibited cell growth, but PGC-1α was maintained at a constant level. Together, these results demonstrate that PGC-1α regulates cell cycle progression through modulation of CyclinD1 and CyclinB1 by ATP and ROS. These findings suggest that PGC-1α potentially coordinates energy metabolism together with the cell cycle.

Same difference: A pilot study of cyclin D1, bcl-2, AMACR, and ALDH-1 identifies significant differences in expression between primary colon adenocarcinoma and its metastases

Tumor heterogeneity implies the possibility of significantly different expression of key pathways between primary and metastatic clones. Colon adenocarcinoma is one of the few tumors where current practice includes resection of primary and isolated organ metastases simultaneously without neoadjuvant therapy. We performed a pilot study on 28 cases of colon adenocarcinoma resected simultaneously with metastases in patients with no history of neoadjuvant therapy. We assayed matched primary and metastatic tumors from each patient with common diagnostic antibodies to Bcl-2, Cyclin D1, AMACR, and ALDH-1 by immunohistochemistry with semi-quantitative interpretation on archived formalin fixed, paraffin embedded samples. We were powered for large, consistent differences between primary and metastatic expression, and found 21 of 28 had a significant difference in expression of at least one of the four proteins, accounting for multiplicity of testing. Cyclin D1 had significantly more cases with differential metastatic:primary expression than would be expected by chance alone (p-value 0.0043), favoring higher expression in the metastatic sample. Bcl-2 and ALDH-1 had trends in this direction (p-value 0.078 each). Proportionately more cases with significant differences were identified when a liver metastasis was tested. We conclude differences in expression between metastatic and primary colon adenocarcinoma within the same patient exist, and may have therapeutic and biomarker testing consequences.

Clinical significance of expression of PI3Kp110α, PI3Kp110β, Bcl-2 and CyclinD1 in primary colorectal cancer and lymph node metastases

AIM: To investigate the expression of phosphatidylinositol 3-kinase (PI3K)p110α, PI3Kp110β, B-cell lymphoma-2 (Bcl-2) and CyclinD1 in primary colorectal cancer (CRC) and lymph node metastases, and to analyze their correlations with clinicopathologic characteristics and prognosis of CRC.

METHODS: Immunohistochemistry was used to detect expression of PI3Kp110α, PI3Kp110β, Bcl-2 and CyclinD1 in 30 cases of normal colorectal mucosa, 52 cases of CRC without lymph node metastasis, 50 cases of primary CRC tissues and corresponding lymph node metastases. The correlations between PI3Kp110α, PI3Kp110β, Bcl-2, and CyclinD1 expression as well as their relationship with clinicopathologic characteristics and prognosis of CRC were analyzed.

RESULTS: The expression of PI3Kp110α and Bcl-2 in CRC without lymph node metastasis, primary CRC tissues and corresponding lymph node metastases was significantly higher than that in normal colorectal mucosa (P < 0.05). PI3Kp110β and CyclinD1 expression was also significantly increased in CRC without lymph node metastasis, primary CRC tissues, and corresponding lymph node metastases compared with the normal colorectal mucosa. What's more, PI3Kp110β and CyclinD1 expression was significantly increased in CRC with lymph node metastases compared with CRC without lymph node metastases (P < 0.05). Spearman analysis showed that PI3Kp110α expression was positively associated with Bcl-2 expression in the four groups (P < 0.05), PI3Kp110α expression was positively associated with CyclinD1 expression in normal colorectal mucosa, CRC without lymph node metastasis, and CRC with lymph node metastasis (P < 0.05), and PI3Kp110β expression was positively correlated with Bcl-2 and CyclinD1 expression in the four groups (P < 0.05). PI3Kp110α, PI3Kp110β and CyclinD1 expression was related to cancer cell differentiation and lymph node metastasis, and Bcl-2 expression was associated with cancer cell differentiation. Kaplan-Meier analysis showed that PI3Kp110α, PI3Kp110β, Bcl-2 and CyclinD1 were prognostic factors for CRC, and Cox proportional hazards regression analysis showed that PI3Kp110α and PI3Kp110β were independent prognostic factors for CRC.

CONCLUSION: PI3Kp110α, PI3Kp110β, Bcl-2, and CyclinD1 expression is increased in primary CRC tissues and lymph node metastases compared with normal mucosa, suggesting that they may play important roles in the development and progression of CRC. PI3Kp110α and PI3Kp110β promote cancer cell growth via Bcl-2 and CyclinD1 in CRC with lymph node metastases. PI3Kp110α, PI3Kp110β, Bcl-2 and CyclinD1 are associated with tumor cell differentiation and CRC metastasis. PI3Kp110α and PI3Kp110β are independent prognostic factors for CRC.

miR-582-5p inhibits proliferation of hepatocellular carcinoma by targeting CDK1 and AKT3

microRNAs play an important role in the progression of hepatocellular carcinoma (HCC). In this study, we found that miR-582-5p expression was downregulated in hepatoma tissues and HCC cell lines. Upregulation of miR-582-5p reduced colony number, inhibited cellular proliferation, and arrested cell cycle in G0/G1 phase. When miR-582-5p was inhibited, the colony number was increased and cellular proliferation and cell cycle were promoted. Further studies showed that miR-582-5p regulated the progression of HCC through directly inhibiting the expression of CDK1 and AKT3, and indirectly inhibiting the expression of cyclinD1.

Inhibition of STAT3/cyclinD1 pathway promotes chemotherapeutic sensitivity of colorectal caner

BACKGROUND

Chemotherapeutic resistance indicated the poor prognosis of colorectal cancer.

OBJECTIVE

Our study aimed to investigate the role of STAT3/cyclinD1 pathway in the chemotherapeutic resistance of colorectal cancer.

METHODS

We firstly measured the expression of cyclinD1 in the colorectal cancer tissues using immunohistochemistry in tissue microarray. Then cell viability and apoptosis were investigated in the HT-29 cell lines dealing with recombinant lentivirus and shRNA to increase or decrease cyclinD1 expression. Furthermore, luciferase and ChIP assays were applied to investigate whether STAT3 regulated cyclinD1 expression by binding to its promoter. Finally, we determined whether inhibition of STAT3 could decrease cyclinD1 and increase the chemotherapy sensitivity.

RESULTS

CyclinD1 expression was significantly increased in the cancer cells and high level of cyclinD1 indicated the poor prognosis. Inhibition of cyclinD1 decreased the cell viability assessed by MTT and increased rate of apoptosis when exposed to 5-FU treatment while overexpression of cyclinD1 showed the reverse effect. ChIP assay showed that STAT3 directly bind to cyclinD1 promoter. Subclone of full promoter of cyclinD1 into pGL4 increased the luciferase activity while delete or mutation of any of STAT3 binding sites resulted in reductions of luciferase activity. Inhibition of STAT3 decreased cyclinD1 expression to decrease the cell viability and increase rate of apoptosis when exposed to 5-FU treatment.

CONCLUSIONS

Inhibition of STAT3/cyclinD1 pathway increased the sensitivity of colorectal cancer cell to chemotherapy.

miR-132/212 cluster inhibits the growth of lung cancer xenografts in nude mice

OBJECTIVE

Lung cancer remains the leading cause of cancer-related death worldwide and microRNAs (miRNAs) play important roles in lung cancer progression. In this study, we investigate the effects of miR-132/212 cluster on the growth of subcutaneous xenografts of human lung cancer H1299 cells in nude mice, and further explore the underlying mechanisms.

METHODS

Nude mice with subcutaneous transplantation tumor of human lung cancer H1299 cells were randomly divided into three groups: the sham group, the control vector group, and the microRNA-132/212 group. The control vector and microRNA-132/212 cluster plasmid was intratumoral injected respectively. Tumor volume was measured during the intervention process, with a tumor growth curve generated. Immunohistochemistry was performed to analyze the expression level of Ki-67, P21, CyclinD1 and CD31 in each group.

RESULTS

The tumor volume of miR-132/212 group was significantly smaller than that of the control group at the terminal time point (P < 0.05). The expression levels of Ki-67, CyclinD1 and CD31 in the miR-132/212 group was significantly lower than the control group (P < 0.05), while the expression levels of P21 in the miR-132/212 group were significantly higher than the control group (P < 0.05).

CONCLUSION

miR-132/212 cluster significantly inhibited the growth of subcutaneous xenografts of human lung cancer H1299 cells in nude mice. The inhibitory effect of miR-132/212 cluster in tumor growth may be mediated by upregulating the expression of P21 and downregulating the expression of CyclinD1, thereby inhibiting tumor tissue proliferation and angiogenesis and resulting in the inhibition of tumor growth.

The p-ERK-p-c-Jun-cyclinD1 pathway is involved in proliferation of smooth muscle cells after exposure to cigarette smoke extract

An epidemiological survey has shown that smoking is closely related to atherosclerosis, in which excessive proliferation of vascular smooth muscle cells (SMCs) plays a key role. To investigate the mechanism underlying this unusual smoking-induced proliferation, cigarette smoke extract (CSE), prepared as smoke-bubbled phosphate-buffered saline (PBS), was used to induce effects mimicking those exerted by smoking on SMCs. As assessed by Cell Counting Kit-8 detection (an improved MTT assay), SMC viability increased significantly after exposure to CSE. Western blot analysis demonstrated that p-ERK, p-c-Jun, and cyclinD1 expression increased. When p-ERK was inhibited using U0126 (inhibitor of p-ERK), cell viability decreased and the expression of p-c-Jun and cyclinD1 was reduced accordingly, suggesting that p-ERK functions upstream of p-c-Jun and cyclinD1. When a c-Jun over-expression plasmid was transfected into SMCs, the level of cyclinD1 in these cells increased. Moreover, when c-Jun was knocked down by siRNA, cyclinD1 levels decreased. In conclusion, our findings indicate that the p-ERK-p-c-Jun-cyclinD1 pathway is involved in the excessive proliferation of SMCs exposed to CSE.

Up-regulation of cyclinD1 and Bcl2A1 by insulin is involved in osteoclast proliferation

AIMS

Insulin receptor signaling in osteoblasts has been well established, but the effects of insulin on osteoclast proliferation are poorly explored. The objective of this study was to investigate the roles and the mechanisms of insulin on osteoclast proliferation.

MAIN METHODS

After insulin treatment to primary osteoclast precursors, BrdU incorporation assay was performed and the expression of cell cycle- and apoptosis-related genes was determined by real-time PCR and immunoblotting. Apoptosis was analyzed using a FACScan flow cytometer.

KEY FINDINGS

Insulin activated insulin receptor and promoted the proliferation of osteoclast precursors in time- and dose-dependent manners. However, the expression of insulin receptor was not changed by it during that time. Insulin remarkably induced the expression of cyclinD1, a cell cycle marker, and Bcl2A1, an anti-apoptotic oncogene, whereas cdk1 and cdk4 were not affected by it. The expression of Bcl2l11 and Bax, both apoptotic markers, was reduced or not changed in osteoclast precursors. Bcl2A1/Bax ratio was also increased in protein levels. Treatment with obatoclax, a Bcl2 family inhibitor, significantly induced the apoptosis of osteoclast precursors in the presence of insulin. These results demonstrate that insulin promotes osteoclast proliferation by increasing cell cycle and suppressing apoptosis through specific gene regulation.

SIGNIFICANCE

These data provide a basis for understanding and ultimately treating several bone-related metabolic diseases.

Maternal choline modifies fetal liver copper, gene expression, DNA methylation, and neonatal growth in the tx-j mouse model of Wilson disease

Maternal diet can affect fetal gene expression through epigenetic mechanisms. Wilson disease (WD), which is caused by autosomal recessive mutations in ATP7B encoding a biliary copper transporter, is characterized by excessive hepatic copper accumulation, but variability in disease severity. We tested the hypothesis that gestational supply of dietary methyl groups modifies fetal DNA methylation and expression of genes involved in methionine and lipid metabolism that are impaired prior to hepatic steatosis in the toxic milk (tx-j) mouse model of WD. Female C3H control and tx-j mice were fed control (choline 8 mmol/Kg of diet) or choline-supplemented (choline 36 mmol/Kg of diet) diets for 2 weeks throughout mating and pregnancy to gestation day 17. A second group of C3H females, half of which were used to cross foster tx-j pups, received the same diet treatments that extended during lactation to 21 d postpartum. Compared with C3H, fetal tx-j livers had significantly lower copper concentrations and significantly lower transcript levels of Cyclin D1 and genes related to methionine and lipid metabolism. Maternal choline supplementation prevented the transcriptional deficits in fetal tx-j liver for multiple genes related to cell growth and metabolism. Global DNA methylation was increased by 17% in tx-j fetal livers after maternal choline treatment (P<0.05). Maternal dietary choline rescued the lower body weight of 21 d tx-j mice. Our results suggest that WD pathogenesis is modified by maternal in utero factors, including dietary choline.

KAI1/CD82 and cyclin D1 as biomarkers of invasion, metastasis and prognosis of laryngeal squamous cell carcinoma

OBJECTIVE

This study aimed to investigate the expressions and significance of KAI1/CD82 and cyclin D1 in laryngeal squamous cell carcinoma (LSCC).

METHODS

Real-time quantitative PCR (Q-PCR) and Western blot assay were employed to detect the expressions of KAI1/CD82 and cyclin D1 in the laryngeal tissues of 86 LSCC patients, 32 patients with laryngeal polyp and 38 patients with laryngeal leukoplakia, and the influence of both proteins on the clinicopathological features and survival of LSCC patients.

RESULTS

The changes in mRNA and protein expressions of KAI1/CD82 and cyclin D1 were consistent in three groups, and the expressions of KAI1/CD82 and cyclin D1 were significantly different among three groups (P<0.01 or <0.05). The KAI1/CD82 expression in patients with TNM stage III-IV LSCC, poorly differentiated LSCC, clinical stage III-IV LSCC or lymph node metastasis was markedly lower than that in those with TNM stage I-II LSCC, well differentiated LSCC, clinical stage I-II LSCC or no lymph node metastasis (P<0.01 or <0.05). However, there was no marked difference in KAI1/CD82 expression between males and females and among patients in different age groups (P>0.05). In LSCC patients positive for KAI1/CD82 protein expression, the median survival time was 76 months, which was significantly longer than that in LSCC patients negative for KAI1/CD82 protein expression (48 months; X(2)=16.293, P=0.000). The Cyclin D1 expression in patients with TNM stage III-IV LSCC, poorly differentiated LSCC, or clinical stage III-IV LSCC was dramatically higher than that in patients with TNM stage I-II LSCC, well differentiated LSCC, or clinical stage I-II LSCC (P<0.01 or <0.05). However, no marked difference was noted in cyclin D1 expression between males and females, among patients in different age groups and between patients with and without lymph node metastasis (P>0.05). In LSCC patients positive for cyclin D1 protein expression, the median survival time was 40 months, which was markedly shorter than that in LSCC patients negative for cyclin D1 protein expression (X(2)=9.517, P=0.02). In LSCC patients, there was a negative correlation between KAI1/CD82 expression and cyclin D1 expression (X(2)=7.86, P<0.01).

CONCLUSION

KAI1/CD82 affects cell cycle. Both KAI1/CD82 and cyclin D1 are involved in the occurrence and development of LSCC, and may provide clinical information for evaluation of invasiveness, metastasis and prognosis of LSCC. Thus, KAI1/CD82 and cyclin D1 may serve as markers for determination of invasiveness, metastasis and prognosis of LSCC.

Treatment with Jian-pi-qing-re-huo-xue detection regulates SW480 cell apoptosis by altering Wnt/β-catenin expression

AIM: To investigate the effect of treatment with Jian-pi-qing-re-huo-xue decoction on SW480 cell proliferation and apoptosis and the expression of β-catenin, TCF-4, c-myc and cyclin D1.

METHODS: SW480 cells were divided into a blank group, an intervention group and a control group, which were incubated with fetal calf serum, different concentrations of serum containing Jian-pi-qing-re-huo-xue decoction, or serum containing mesalamine for 24 h, respectively. The proliferation and apoptosis of SW480 cells were detected by MMT assay and flow cytometry, respectively. The mRNA and protein expression of β-catenin, TCF-4, c-myc, and cyclin D1 was assayed by real-time PCR and Western blot.

RESULTS: Compared to the blank group, the survival of SW480 cells was reduced in the intervention group (P < 0.05). When the dilution concentration of Jian-pi-qing-re-huo-xue decoction was 5%, 10%, 15%, 20% and 30%, the reduced rate of cell growth was 28%, 44.58%, 65.86%, 57.86% and 49.89%, respectively. However, this inhibitory effect was not concentration-dependent (P > 0.05). Intervention with Jian-pi-qing-re-huo-xue decoction significantly increased the percentage of cells at S phase and decreased that of cells at G1 in a concentration-dependent manner compared to the control group (both P < 0.05). β-catenin was more abundantly expressed in the nucleus in the blank group. In the intervention group, the ectopic expression of β-catenin in the cytoplasm and nucleus declined, and membrane expression increased (P < 0.05). Treatment with Jian-pi-qing-re-huo-xue decoction induced cell apoptosis and down-regulated the expression of β-catenin, TCF-4, c-myc, and cyclin D1 compared to the blank group (P < 0.01), and the effect was more significant when middle concentration of serum containing the decoction was used.

CONCLUSION: Jian-pi-qing-re-huo-xue decoction exerts a distinct preventive and therapeutic effect on colon cancer possibly by altering the expression of Wnt/β-catenin, affecting cell cycle progression and inducing cell apoptosis.

Cyclin D1/Cdk4 increases the transcriptional activity of FOXM1c without phosphorylating FOXM1c

Anders et al. (2011) [11] reported that cyclinD1/Cdk4 and cyclinD3/Cdk6 enhance the transcriptional activity of FOXM1c by phosphorylating its TAD. They defined 12 Cdk consensus sites as essential for the activation of FOXM1c by cyclinD1/Cdk4 and cyclinD3/Cdk6 and stated that the 12 Cdk-sites are positioned within the TAD of FOXM1c. In contrast, this study demonstrates that all potential cyclin/Cdk phosphorylation sites S/T-P of FOXM1c are located outside its TAD so that the TAD of FOXM1c contains no potential cyclin/Cdk site, which excludes a phosphorylation of the FOXM1c-TAD by cyclinD1/Cdk4 and cyclinD3/Cdk6. This study shows that the activation of FOXM1c by cyclinD1/Cdk4 is lost without removal of any cyclin/Cdk site and gained without addition of any cyclin/Cdk site because it depends on a FOXM1c domain with no potential cyclin/Cdk site, namely on the interaction domain for the tumor suppressor RB, which binds to and represses FOXM1c. CyclinD1/Cdk4 activates FOXM1c because cyclinD1/Cdk4 releases FOXM1c from its repression by RB through removal of RB from FOXM1c. For this purpose, cyclinD1/Cdk4 phosphorylates only RB, but not FOXM1c, so that cyclinD1/Cdk4 increases the transcriptional activity of FOXM1c without phosphorylating FOXM1c and activates FOXM1c independently of cyclin/Cdk phosphorylation sites in FOXM1c. In summary, this study changes the model of Anders et al. (2011) [11] completely because it disproves their central conclusion that cyclinD1/Cdk4 and cyclinD3/Cdk6 enhance the transcriptional activity of FOXM1c by phosphorylating its TAD at the 12 Cdk-sites.

miR-338-3p Is Down-Regulated by Hepatitis B Virus X and Inhibits Cell Proliferation by Targeting the 3’-UTR Region of CyclinD1. Int J Mol Sci. 2012;13:8514-8539. [PMID: 22942717 PMCID: PMC3430248 DOI: 10.3390/ijms13078514]

Hepatitis B virus X protein (HBx) is recognized as an oncogene in hepatocellular carcinoma (HCC). HBx regulates microRNA expression, including down-regulating miR-338-3p in LO2 cells. Here, we investigated miR-338-3p function in HBx-mediated hepatocarcinogenesis. In 23 HBV-infected HCC clinical patient tumor and adjacent non-tumor control tissues, 17 and 19 tumors expressed HBx mRNA and protein, respectively. When considered as a group, HBV-infected HCC tumors had lower miR-338-3p expression than controls; however, miR-338-3p was only significantly down-regulated in HBx-positive tumors, indicating that HBx inversely correlated with miR-338-3p. Functional characterization of miR-338-3p indicated that miR-338-3p mimics inhibited cell proliferation by inducing cell cycle arrest at the G1/S phase as assessed by EdU and cell cycle assays in HBx-expressing LO2 cells. CyclinD1, containing two putative miR-338-3p targets, was confirmed as a direct target using 3′-UTR luciferase reporter assays from cells transfected with mutated binding sites. Mutating the 2397–2403 nt binding site conferred the greatest resistance to miR-338-3p suppression of CyclinD1, indicating that miR-338-3p suppresses CyclinD1 at this site. Overall, this study demonstrates that miR-338-3p inhibits proliferation by regulating CyclinD1, and HBx down-regulates miR-338-3p in HCC. This newly identified miR-338-3p/CyclinD1 interaction provides novel insights into HBx-mediated hepatocarcinogenesis and may facilitate therapeutic development against HCC.

Clinical significance of expression of livin and cyclin D1 in chronic atrophic gastritis with intestinal metaplasia

AIM: To investigate the expression of livin and cyclinD1 in chronic atrophic gastritis with intestinal metaplasia.

METHODS: Immunohistochemistry was used to examine the expression of livin and cyclin D1 in 30 cases of chronic superficial gastritis, 35 cases of atrophic gastritis without intestinal metaplasia, 35 cases of atrophic gastritis with intestinal metaplasia, and 30 cases of gastric carcinoma. We also explored the correlation between livin and cyclin D1 expression in chronic atrophic gastritis and gastric carcinoma.

RESULTS: The positive rates of livin expression in the specimens of chronic superficial gastritis, atrophic gastritis without intestinal metaplasia, atrophic gastritis with intestinal metaplasia, and gastric carcinoma were 0%, 28.57%, 45.71% and 66.67%, respectively, and the corresponding rates for cyclin D1 expression were 10%, 14.29%, 37.14% and 53.33%. The positive rates of livin and cyclinD1 expression were significantly higher in atrophic gastritis with intestinal metaplasia than in chronic superficial gastritis (both P < 0.05). The expression of cyclin D1 differed significantly between atrophic gastritis with and without intestinal metaplasia (P < 0.05). The expression of livin has a positive correlation with that of cyclin D1 in atrophic gastritis with intestinal metaplasia and gastric carcinoma.

CONCLUSION: The positive rates of livin and cyclin D1 expression increase in atrophic gastritis with intestinal metaplasia and gastric carcinoma. No significant difference was observed for the expression of livin and cyclin D1 between atrophic gastritis with intestinal metaplasia and gastric carcinoma. Livin and cyclin D1 may play a very important role in the development of gastric carcinoma and be used as markers for early diagnosis of gastric carcinoma.

Involvement of the APC/β-catenin/TCF signaling pathway in the regulatory effects of octreotide on SW480 colon cancer cells

AIM: To investigate whether the APC/β-catenin/TCF signaling pathway is involved in the regulatory effects of octreotide (OCT) on SW480 colon cancer cells.

METHODS: (1) mRNA testing: SW480 cells were cultured in vitro and divided into control group and OCT group (treated with 10^-10 mol/L OCT). Total RNA was prepared from the two groups of cells and used to detect the mRNA expression of APC2, AXIN, CK1α, cyclin D1 and FZD7 by RT-PCR. (2) Protein testing: SW480 cells were cultured in vitro and divided into control group and OCT group (treated with /L OCT at a concentration of 10^-14, 10^-12 or 10^-10 mol/L). Total protein was prepared from the two groups of cells and used to detect the protein expression of APC2, CK1α and CyclinD1 by Western blot.

RESULTS: (1) mRNA testing: Treatment with OCT increased the mRNA levels of APC2 and CK1α (both P < 0.05), decreased that of cyclin D1 (P < 0.05), but had no significant impact on those of FZD7 and axin (both P > 0.05) in SW480 cells; (2) Protein testing: Treatment with different concentrations of OCT increased the protein levels of APC2 and CK1α and decreased that of cyclin D1 in SW480 cells in a dose-dependent manner (all P < 0.05).

CONCLUSION: OCT can negatively regulate APC/β-catenin/TCF signaling by up-regulating APC2 and CK1α expression and down-regulating cyclin D1 expression.

Expression of RASSF1A and CyclinD1 in gastric cancer and premalignant lesion and its significance

AIM: To investigate the role of RASSF1A and CyclinD1 in the development of gastric cancer.

METHODS: RT-PCR was used to detect the mRNA expression of RASSF1A and CyclinD1 in 20 cases of normal gastric tissues, gastric adenoma and atypical hyperplasia, and 40 cases of gastric adenocarcinoma while Western blot was adopted to detect the protein expression of RASSF1A.

RESULTS: The expression of RASSF1A was lower in gastric adenocarcinoma than in atypical hyperplasia, gastric adenoma and normal gastric tissues (37.5% vs 80.0%, 95.0%, 100.0%, all P < 0.05). However, the expression of CyclinD1 was significantly higher than in atypical hyperplasia, gastric adenoma and normal gastric tissues (77.5% vs 25.0%, 10.0%, 5.0%, all P < 0.05). In gastric cancer tissues, both of the expressions of RASSF1A and CyclinD1 mRNA were associated with pathological grade (χ² = 4.422, P < 0.05; χ² = 8.935, P < 0.05); their expressions were negatively correlated(r = -0.448, P < 0.05), while the expressions of RASSF1A protein and mRNA were consistent.

CONCLUSION: The silent expression of RASSF1A and the increased expression of CyclinD1 may play an important role in gastric cancer pathogenesis. Their combined detection can contribute to the earlier diagnosis and treatment of gastric cancer.

Expression of RASSF1A and CyclinD1 in gastric mucosal lesions and their correlations

AIM: To investigate the expression of Ras association domain family 1A gene (RASSF1A) and CyclinD1 as well as their correlations in gastric mucosal lesions.

METHODS: We detected the expression of RASSF1A and CyclinD1 in tissue specimens of gastric cancer (n = 69), chronic superficial gastritis (n = 45), chronic atrophic gastritis (n = 45), chronic gastritis accompanied with intestinal metaplasia (n = 45) and chronic gastritis accompanied with atypical hyperplasia (n = 47) using SP immunohistochemistry.

RESULTS: The positive rate of RASSF1A expression was significantly lower in gastric carcinoma than that in chronic superficial gastritis (χ² = 10.4, P < 0.05); In the mucosa of precancerous lesions, the expression of RASSF1A protein was decreased gradually (χ² = 28.7, P < 0.05), and obviously correlated with the degrees of tumor differentiation (P < 0.05). CyclinD1 protein was hardly expressed in chronic superficial gastritis, but its expression was significantly elevated in gastric cancer (84.1%). The expression of CyclinD1 was increased gradually in the mucosa of precancerous lesions (χ² = 11.9, P < 0.05), and it was markedly higher in gastric carcinoma than that in the other lesions (χ² = 22.0, 19.6, 29.4; all P < 0.01). There was a negative correlation between the expression of RASSF1A and CyclinD1 protein in gastric carcinoma (r_s = -0.323, P < 0.05).

CONCLUSION: RASSF1A expression is down-regulated while CyclinD1 expression is up-regulated in gastric mucosa during the evolution process of chronic superficial gastritis→chronic atrophic gastritis→intestinal metaplasia→gastric dysplasia→gastric carcinoma. Combined detection of the two markers may help to study the mechanism of gastric cancer pathogenesis and development.

Mechanisms involved in ceramide-induced cell cycle arrest in human hepatocarcinoma cells

AIM: To investigate the effect of ceramide on the cell cycle in human hepatocarcinoma Bel7402 cells. Possible molecular mechanisms were explored.

METHODS: [3- (4, 5)-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay, plasmid transfection, reporter assay, FACS and Western blotting analyses were employed to investigate the effect and the related molecular mechanisms of C2-ceramide on the cell cycle of Bel7402 cells.

RESULTS: C2-ceramide was found to inhibit the growth of Bel7402 cells by inducing cell cycle arrest. During the process, the expression of p21 protein increased, while that of cyclinD1, phospho-ERK1/2 and c-myc decreased. Furthermore, the level of CDK7 was downregulated, while the transcriptional activity of PPARγ was upregulated. Addition of GW9662, which is a PPARγ specific antagonist, could reserve the modulation action on CDK7.

CONCLUSION: Our results support the hypothesis that cell cycle arrest induced by C2-ceramide may be mediated via accumulation of p21 and reduction of cyclinD1 and CDK7, at least partly, through PPARγ activation. The ERK signaling pathway was involved in this process.