抑癌基因MTUS1在结直肠癌的表达与其淋巴结转移呈负相关

微管相关肿瘤抑制基因1(MTUS1)是一个新的肿瘤抑制基因,编码血管紧张素II AT受体结合蛋白（ATIPs）. MTUS1基因表达下调可促进肿瘤细胞增殖,但MTUS1基因表达在结直肠癌转移中的作用尚不知晓.本文以接受根治性手术、经病理检查证实的50例结直肠癌患者新鲜癌组织、癌旁组织和远癌组织为材料,探索MTUS1基因表达与结直肠癌淋巴结转移的关系. 荧光定量PCR及蛋白质免疫印迹揭示,有淋巴结转移的结直肠癌患者的癌及癌旁组织MTUS1 基因表达的mRNA及蛋白质水平明显低于无淋巴结转移的患者. MTUS1 蛋白质在淋巴结转移的结直肠癌患者的癌及癌旁组织表达下调,并进一步得到免疫组织化学的验证.实验结果提示,MTUS1的表达量与肿瘤的侵润深度有明显的负相关性.结合临床资料,推断抑癌基因MTUS1在肿瘤的发生、发展及淋巴转移中发挥重要作用.     

Deregulated expression of homeobox-containing genes, HOXB6, B8, C8, C9, and Cdx-1, in human colon cancer cell lines

Previously we have demonstrated a reciprocal deregulation of various homeobox genes (HOXB6, B8, C8 and C9 vs Cdx-1) in human colorectal cancer (CRC). In the present study, using RT-PCR, we have investigated the expression pattern of these homeobox genes in various human colon cell lines, representing various stages of colon cancer progression and differentiation. Thus, we have tested polyposis coli Pc/AA adenoma cells, Caco-2, HT-29 and LS174T adenocarcinoma cell lines. All cell lines, except LS174T, demonstrated a pattern of deregulated homeobox gene expression which resembled that of CRC. In contrast, the pattern of expression of these genes in the highly oncogenic LS174T cells, as well as in Caco-2 cells transfected with activated Ha-ras or Polyoma middle T oncogene, resembled that of the normal mucosa. The reciprocal deregulation of HOX and Cdx-1 genes in CRC and in CRC-derived cell lines suggests a possible role in human CRC development.     

Epigenetic modifications of metastasis suppressor genes in colon cancer metastasis

Colon and rectal cancer (colorectal cancer, CRC) is the third most common cancer worldwide. Deaths from CRC account for around 8% of all cancer deaths, making it the fourth most common cause of death from cancer. The high mortality rate of colon cancer is mainly attributable to its metastasis. Efforts have been made to identify metastasis suppressor genes, which encode proteins responsible for inhibiting the metastasis but not suppressing the growth of primary tumors. Studies on metastasis suppressor genes demonstrated that epigenetic modifications, such as DNA promoter methylation and histone modification, play crucial roles in regulating the expression of many metastasis suppressor genes, which indicates the association between aberrant epigenetic alterations and cancer metastasis. This review will focus on the recent findings regarding metastasis suppressors regulated by epigenetic modifications, particularly DNA methylation and histone modification, in CRC metastasis. Also discussed will be recent progress on the suppression of CRC metastasis by genistein, a soy isoflavone, with a focus on epigenetic mechanisms.     

HOXD8 inhibits the proliferation and migration of triple-negative breast cancer cells and induces apoptosis in them through regulation of AKT/mTOR pathway

HOXD8 (Homeobox D8) functions as an apoptotic inducer to suppress tumor progression. However, the role of HOXD8 in triple-negative breast cancer (TNBC) has not been fully understood. Firstly, HOXD8 was found to be reduced in TNBC tissues based on the TCGA samples through Ualcan (http://ualcan.path.uab.edu/analysis.html) prediction. Moreover, data from qRT-PCR and western blot confirmed the lower expression of HOXD8 in the TNBC tissues or cells than that in paracancerous tissues or human mammary epithelial cell line (MCF10A), respectively. Secondly, pcDNA-mediated over-expression of HOXD8 were conducted in TNBC cells, and the gain-of functional assays showed that over-expression of HOXD8 promoted TNBC cell progression with repressed cell apoptosis and induced proliferation, migration and invasion. Moreover, xenografted mouse model was constructed by injection of tumor cell line with stable over-expression of HOXD8 to assess the in vivo tumor growth, and the results revealed that over-expression of HOXD8 inhibited tumor growth. Lastly, our results showed that AKT and mTOR phosphorylation were repressed by HOXD8 over-expression in TNBC cells. In conclusion, HOXD8 functioned as an apoptotic inducer to suppress TNBC cell growth and progression by inhibition of AKT/mTOR pathway.     

HOXC5 and HOXC8 expression are selectively turned on in human cervical cancer cells compared to normal keratinocytes

A growing number of data have sustained the involvement of homeobox genes expression deregulation in cancer. In this study, we have performed an exhaustive survey of the expression of the 39 class I HOX genes expressed in normal and malignant human cervix keratinocytes. Using RT-PCR, we observed that the vast majority (34/39) of HOX genes are expressed in normal keratinocytes. Only HOXA2, HOXA7, HOXC5, HOXC8 and HOXD12 were found to be silent. Interestingly, this pattern is conserved in the transformed keratinocytes (SiHa cells) except for the appearance of HOXC5 and HOXC8 mRNA. The HOXC5 and HOXC8 expression was also observed in two other transformed keratinocytes cell lines of independent origins, Eil-8 and 18-11S3, and confirmed by in situ hybridization. Our data add weight to the body of evidence attributing to a specific adult tissue a particular combination of expressed HOX genes and suggest that HOXC5 and/or HOXC8 could be involved in the process leading to the transformation of cervical keratinocytes.     

Proteomic-based identification of the APC-binding protein EB1 as a candidate of novel tissue biomarker and therapeutic target for colorectal cancer

Novel candidates of biomarker and therapeutic target in colorectal cancer (CRC) were investigated using a proteomic approach. The proteome of normal colorectal epithelial tissues was compared with that of the tumor ones in 59 CRC patients using two-dimensional difference gel electrophoresis. Of 3458 protein spots, 110 exhibited statistically significant (p<0.01) differences in intensity (more than 2.5-folds) between the normal and tumor tissue groups. Of 67 unique gene products that were identified for 105 of the 110 protein spots, we focused on the higher expression of the adenoma polyposis coli-binding protein EB1 (EB1). EB1 was originally discovered as a binding protein of APC, which is a tumor suppressor gene product, and the expression of EB1 has been associated with poor prognosis in several malignancies but not in CRC. Immunohistochemical analysis of the 132 CRC cases revealed that EB1 was overexpressed in tumor cells in correlation with poor prognosis. Suppression of EB1 by RNAi inhibited CRC cell proliferation and invasion. In this study, the overexpression of EB1 in CRC tissues correlating with prognosis, and its functional contribution to the malignant phenotypes of CRC cells are described. The present findings indicate that EB1 is a potential biomarker and therapeutic target in CRC.     

Investigation of expression of HOX 2C and HOX 4B homeobox genes in human colorectal cancer by using an RT-PCR method

Investigation of expression of both HOX 2C and HOX 4B homeobox genes in the same patient with colorectal cancer was proposed by using an RT-PCR method. In order to conduct this investigation, PCR products of 445 bp of HOX 2C and 301 bp of HOX 4B were amplified in both tumor and normal samples of ten patients. Expressions of HOX 2C gene were observed in both tumor and normal samples of four patients and in only a tumor sample of one patient, while the expression was not observed in both tumor and normal samples of five patients. Expressions of HOX 4B gene were not observed in both tumor and normal samples of ten patients.In the present study, it was found that individuality seems to be important. The results of these two genes, observed in patients with colorectal cancer, should be taken into consideration for further researches.     

HOTAIRM1 as a potential biomarker for diagnosis of colorectal cancer functions the role in the tumour suppressor

Recent studies have revealed many different long noncoding RNAs (lncRNA), however, the investigation for their function and clinical value as tumour biomarkers has scarcely begun. Here, we found that expression of HOTAIRM1 was reduced in colorectal cancer (CRC) tissues compared with matched normal tissues, and plasma HOTAIRM1 levels in CRC patients were less than in controls. The cut‐off point was chosen as 0.003 with a sensitivity of 64.00% and a specificity of 76.50% in the validation set. The performance of HOTAIRM1 was highly comparable to carcinoembryonic antigen (CEA), and better than CA19‐9 and CA125. The combined assay of HOTAIRM1 and CEA raised the sensitivity and specificity to 84.00%. HOTAIRM1 knockdown resulted in obvious changes in expression of the cell proliferation related to genes and promoted cell proliferation. HOTAIRM1 plays a role of tumour suppressor in CRC; Down‐regulation of HOTAIRM1 can serve as a biomarker for CRC, and combined HOTAIRM1 and CEA assay might provide a promising diagnosis for CRC.     

Identification and distribution of thioredoxin-like 2 as the antigen for the monoclonal antibody MC3 specific to colorectal cancer

MC3 is a colorectal cancer (CRC)-specific mAb previously prepared in our laboratory that can detect CRC with high sensitivity and specificity. However, the target antigen for MC3 had not been identified due to technological limitations. In the present study, immunocytochemistry and immunohistochemistry revealed the expression patterns of MC3 antigen (MC3-Ag) in colon cancer cell lines and CRC tissues. Western blotting analysis showed that the MC3 antibody reproducibly recognized two approximately 30 kDa proteins in the total cell lysates of human colon carcinoma cell lines SW480 and HT-29. Using a proteomic approach, we identified two MC3 immunoreactive spots as two isoforms of thioredoxin-like 2 (Txl-2) protein. Further paired immunostaining showed that Txl-2 had the same expression profile as probed by the MC3 antibody. Western blotting also showed that both antibodies could detect the same two bands, further verifying that Txl-2 is the antigen of MC3 antibody. Additionally, tissue arrays revealed the expression patterns of Txl-2 in various normal and cancer tissues. Further analysis showed that Txl-2 mRNA was elevated in 18 cases of CRC tissues compared to paracancerous tissues and adjacent normal tissues.     

DNA methylome profiling identifies novel methylated genes in African American patients with colorectal neoplasia

The identification of genes that are differentially methylated in colorectal cancer (CRC) has potential value for both diagnostic and therapeutic interventions specifically in high-risk populations such as African Americans (AAs). However, DNA methylation patterns in CRC, especially in AAs, have not been systematically explored and remain poorly understood. Here, we performed DNA methylome profiling to identify the methylation status of CpG islands within candidate genes involved in critical pathways important in the initiation and development of CRC. We used reduced representation bisulfite sequencing (RRBS) in colorectal cancer and adenoma tissues that were compared with DNA methylome from a healthy AA subject’s colon tissue and peripheral blood DNA. The identified methylation markers were validated in fresh frozen CRC tissues and corresponding normal tissues from AA patients diagnosed with CRC at Howard University Hospital. We identified and validated the methylation status of 355 CpG sites located within 16 gene promoter regions associated with CpG islands. Fifty CpG sites located within CpG islands—in genes ATXN7L1 (2), BMP3 (7), EID3 (15), GAS7 (1), GPR75 (24), and TNFAIP2 (1)—were significantly hypermethylated in tumor vs. normal tissues (P < 0.05). The methylation status of BMP3, EID3, GAS7, and GPR75 was confirmed in an independent, validation cohort. Ingenuity pathway analysis mapped three of these markers (GAS7, BMP3 and GPR) in the insulin and TGF-β1 network—the two key pathways in CRC. In addition to hypermethylated genes, our analysis also revealed that LINE-1 repeat elements were progressively hypomethylated in the normal-adenoma-cancer sequence. We conclude that DNA methylome profiling based on RRBS is an effective method for screening aberrantly methylated genes in CRC. While previous studies focused on the limited identification of hypermethylated genes, ours is the first study to systematically and comprehensively identify novel hypermethylated genes, as well as hypomethylated LINE-1 sequences, which may serve as potential biomarkers for CRC in African Americans. Our discovered biomarkers were intimately linked to the insulin/TGF-B1 pathway, further strengthening the association of diabetic disorders with colon oncogenic transformation.     

A group 13 homeodomain is neither necessary nor sufficient for posterior prevalence in the mouse limb

Posterior prevalence is the general property attributed to HOX proteins describing the dominant effect of more posterior HOX proteins over the function of anterior orthologs in common areas of expression. To explore the HOX group 13 protein domains required for this property, we used the mouse Prx-1 promoter to drive transgenic expression of Hox constructs throughout the entire limb bud during development. This system allowed us to conclusively demonstrate a hierarchy of Hox function in developing limbs. Furthermore, by substituting the HOXD11 or HOXA9 homeodomain for that of HOXD13, we show that a HOXD13 homeodomain is not necessary for posterior prevalence. Proximal expression of these chimeric proteins unexpectedly caused defects consistent with wild-type HOXD13 mediated posterior prevalence. Moreover, group 13 non-homeodomain residues appear to confer the property as proximal expression of HOXA9 containing the HOXD13 homeodomain did not result in limb reductions characteristic of HOXD13. These data are most compatible with models of posterior prevalence based on protein-protein interactions and support examination of the N-terminal non-homeodomain regions of Hox group 13 proteins as necessary agents for posterior prevalence.