Adiponectin deficiency enhances colorectal carcinogenesis and liver tumor formation induced by azoxymethane in mice

AIM:To investigate the causal relationship between hypoadiponectinemia and colorectal carcinogenesis in in vivo experimental model,and to determine the con-tribution of adiponectin defi ciency to colorectal cancer development and proliferation.METHODS:We examined the influence of adiponectin defi ciency on colorectal carcinogenesis induced by the administration of azoxymethane(AOM)(7.5 mg/kg,in-traperitoneal injection once a week for 8 wk),by using adiponectin-knockout(KO) mice.RESULTS:At 53 wk after the fi rst AOM treatment,KOmice developed larger and histologically more progres-sive colorectal tumors with greater frequency com-pared with wild-type(WT) mice,although the tumor incidence was not different between WT and KO mice.KO mice showed increased cell proliferation of colorec-tal tumor cells,which correlated with the expression levels of cyclooxygenase-2(COX-2) in the colorectal tumors.In addition,KO mice showed higher incidence and frequency of liver tumors after AOM treatment.Thirteen percent of WT mice developed liver tumors,and these WT mice had only a single tumor.In contrast,50% of KO mice developed liver tumors,and 58% of these KO mice had multiple tumors.CONCLUSION:Adiponectin deficiency enhances colorectal carcinogenesis and liver tumor formation induced by AOM in mice.This study strongly suggests that hypoadiponectinemia could be involved in the pathogenesis for colorectal cancer and liver tumor in human subjects.

Evaluation of Tumor Formation of Three Bladder Cancer Cell Lines in Nude Mice

This study examined the differences in tumor formation of three bladder tumor cell lines （BIU-87, T24 and EJ） after subcutaneously transplanted into nude mice, in order to find the best technique for establishing in vivo bladder tumor model. BIU-87, T24 and EJ cells at logarithmic phase were re-suspended in serum-free medium. The cells suspensions of the identical concentration were subcutaneously transplanted into nude mice and then the success rate and tumor growth were compared among the three cell groups. The results of tumor formation were pathologically evaluated. Lung, liver and kidney tissues were also pathologically examined for distant metastasis. The proliferation of the three cells were determined by immunohistochemically detecting the PCNA expression in the tumors. The results showed that the success rates of EJ and T24 cells were significantly higher than that of BIU-87 cells and no distant metastasis was noted among the three groups. The proliferation levels of EJ and T24 cells was significantly higher than that of BIU-87. But at the later stage of tumor formation, as compared with T24 cells, EJ grew more vigorously, soon resulting in the central necrosis of tumor, which affected the measurement of the actual size of the tumors. Moreover, PCNA staining exhibited that the proliferation of EJ and T24 was significantly higher than that of BIU-87 cells. It is concluded that as compared with BIU-87 cells, EJ and T24 cells had higher success rates, with not significant differences in death rate and distant metastasis found among them. There existed no significant difference in tumor formation between EJ and T24 cells and T24 cells do not rupture easily, which makes it a better cell line for the establishment of in vivo bladder tumor model.

miR-30a-5p/PHTF2 axis regulates the tumorigenesis and metastasis of lung adenocarcinoma

Background:Lung adenocarcinoma is a very pervasive histological form of lung cancers,and inhibiting metastasis is crucial for effective treatment.In this investigation,we explored the functional interaction of miR-30a-5p and the putative transcription factor 2 of the homeodomain(PHTF2)in dictating the aggressiveness and metastasis of lung adenocarcinoma.Method:We collected clinical samples to evaluate the expression patterns of miR-30a-5p and PHTF2 in lung adenocarcinoma along with normal tissues.Cellular experiments including cell count kit(CCK)-8 growth assay,apoptosis analysis,migration and invasion examinations were performed to assess the aggressiveness of lung adenocarcinoma cells.Furthermore,we examined tumorigenesis and metastasis in a nude mouse model.Results:MiR-30a-5p exhibited downregulation pattern in lung adenocarcinoma samples.Transfection of miR-30a-5p mimic in lung adenocarcinoma cells resulted in the suppression of malignant characteristics.Notably,the administration of miR-30a-5p mimic also curbed tumorigenesis and metastasis of lung adenocarcinoma cells in animal model.Moreover,PHTF2 was found to be a molecular target of miR-30a-5p.Upregulating PHTF2 counteracted the tumor-suppressive effect of the miR-30a-5p mimic.Conclusion:miR-30a-5p functions as a tumor-suppressive molecule while PHTF2 acts as an oncogenic factor in the development and metastasis of lung adenocarcinoma.Therefore,targeting miR-30a-5p and PHTF2 could be developed into a promising therapeutic approach for inhibiting metastasis in lung adenocarcinoma.

Are Cancer Stem Cells the Sole Source of Tumor?

Tumors are believed to consist of a heterogeneous population of tumor ceils originating from rare cancer stem cells （CSCs）. However, emerging evidence suggests that tumor may also origi- nate from non-CSCs. To support this viewpoint, we are here to present definitive evidence indicating that the number of tumorigenic tumor cells is greater than that of CSCs in tumor, and tumor can also derive from non-CSCs. To achieve this, an idealized mathematical model was employed in the pre- sent study and theoretical calculation revealed that non-CSCs could initiate the occurrence of tumor if their proliferation potential was adequate. Further, experimental studies demonstrated that 17.7%, 38.6% and 5.2% of tumor cells in murine B16 solid melanoma, H22 hepatoma and Lewis lung carci2 noma, respectively, were potentially tumorigenic. Thus, based on the aforementioned findings, we propose that the scarce CSCs, if exist, are not the sole source of a tumor.

BRCA1 affects global DNA methylation through regulation of DNMT1

Global DNA hypomethylation at CpG islands coupled with local hypermethylation is a hallmark for breast cancer, yet the mechanism underlying this change remains elusive. In this study, we showed that DNMT1, which encodes a methylation maintenance enzyme, is a transcriptional target of BRCA1. BRCA1 binds to the promoter of the DNMT1 gene through a potential OCT1 site and the binding is required for maintaining a transcriptional active configuration of the promoter in both mouse and human cells. We further demonstrated that impaired function of BRCA1 leads to global DNA hypomethylation, loss of genomic imprinting, and an open chromatin configuration in several types of tissues examined in a BRCA1 mutant mouse model at premaligant stages. BRCA1 deficiency is also associated with significantly increased expression levels of several protooncogenes, including c-Fos, Ha-Ras, and c-Myc, with a higher expression in tumors, while premalignant mammary epithelial cells displayed an intermediate state between tumors and controls. In human clinical samples, reduced expression of BRCA1 correlates with decreased levels of DNMT1, and reduced methylation of CpG islands. Thus, BRCA1 prevents global DNA hypomethylation through positively regulating DNMT1 expression, and this provides one of mechanisms for BRCAl-associated breast cancer formation.

LncRNA C9orf139 can regulate the growth of pancreatic cancer by mediating the miR-663a/Sox12 axis

BACKGROUND Recent studies have proved the important role of many oncogenic long noncoding RNAs(lncRNAs) in the progression of pancreatic cancer, but little is known about the mechanisms of tumor suppression in pancreatic cancer.AIM To evaluate the function of tumor suppressor lncRNA C9orf139 in pancreatic cancer progression and to study the underlying mechanism.METHODS We assigned 54 patients with pancreatic ductal adenocarcinoma treated at our hospital to the patient group and 30 normal subjects undergoing physical examination to the control group. RT-qPCR was used to measure the relative expression of C9orf139 in the tissue and serum of patients, in an attempt to investigate the prognostic value of C9orf139 in pancreatic cancer patients. The luciferase reporter gene assay was performed to determine the interaction between C9orf139 and miR-663 a. The biological function of C9orf139 was assessed by in vitro assays and in vivo subcutaneous tumor formation tests in animal models. To figure out the molecular mechanism of C9orf139 to act on miR-663 a/Sox12, RNA pull-down, Western blot assay, RNA immunoprecipitation assay, and co-immunoprecipitation assay were performed.RESULTS C9orf139 level significantly increased in the tissue and serum of patients, which had clinical diagnostic value for pancreatic cancer. Patients with high C9orf139 expression had a higher risk of progressing to stage Ⅲ + Ⅳ, lymph node metastasis, and poor differentiation. Cox regression analysis suggested that C9orf139, tumor-node-metastasis stage, and lymph node metastasis were independent prognostic factors in patients. The underlying mechanism of C9orf139 was that it promoted the growth of pancreatic cancer cells by modulating the miR-663 a/Sox12 axis.CONCLUSION C9orf139 is highly expressed in pancreatic cancer, qualified to be used as a potential diagnostic and prognostic marker for pancreatic cancer. Its promotion of pancreatic cancer cell growth is achieved by mediating the miR-663 a/Sox12 axis.

Tumor-associated Exosomes Are Involved in Hepatocellular Carcinoma Tumorigenesis, Diagnosis, and Treatment

Hepatocellular carcinoma(HCC)has become a challenging disease worldwide.There are still limitations in the diagnosis and treatment of HCC,and its high metastatic capacity and high recurrence rate are the main reasons for its poor prognosis.The ability of extracellular vesicles(EVs)to transfer functionally-active substances and their widespread presence in almost all body fluids suggest their unprecedented potential in the study of various cancers.The unique physicochemical properties of EVs determine their potential as antitumor vaccines and drug carriers.In the last decade,the study of EVs in HCC has evolved from a single hot topic to a system with considerable scale.This paper summarizes the role of EVs,especially exosomes,in the occurrence,metastasis and tumor immunity of HCC,reviews their applications in tumor diagnosis,prognosis and treatment,describes the pros and cons of these studies,and looks forward towards the future research directions of EVs in HCC.