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Abstract Background Cancer/testis antigen MAGEC2 (also known as HCA587) is highly expressed in a wide variety of tumors and plays an active role in promoting growth and metastasis of tumor cells. However, little is known for the regulation of MAGEC2 expression in cancer cells. Methods Western blotting and quantitative RT-PCR were performed to analyze MAGEC2 expression. Co-immunoprecipitation assay was applied for detecting the endogenous interaction of MAGEC2 and TRIM28 in tumor cells. Overexpression and knockdown assays were used to examine the effects of TRIM28 on the expression of MAGEC2 protein. Immunohistochemistry (IHC) staining was performed in hepatocellular carcinoma patients to evaluate the association between the expression of MAGEC2 and TRIM28. Proteasome inhibitors MG132 or PS-341 and lysosome inhibitor Chloroquine (CQ) were used to inhibit proteasomal or lysosomal-mediated protein degradation respectively. Results We demonstrate that MAGEC2 interacts with TRIM28 in melanoma cells and MAGEC2 expression in tumor cells depends on the expression of TRIM28. The expression level of MAGEC2 protein was significantly reduced when TRIM28 was depleted in tumor cells, and no changes were observed in MAGEC2 mRNA level. Furthermore, expression levels of MAGEC2 and TRIM28 are positively correlated in MAGEC2-positive human hepatocellular carcinoma tissues (p = 0.0011). Mechanistic studies indicate that the regulatory role of TRIM28 on MAGEC2 protein expression in tumor cells depends on proteasome-mediated pathway. Conclusions Our findings show that TRIM28 is necessary for MAGEC2 expression in cancer cells, and TRIM28 may serve as a new potential target for immunotherapy of cancer.

Background: KIF23 (kinesin family member 23) is a kinesin-like motor protein and plays an important role in cytokinesis. In search for genes associated with hepatocellular carcinoma (HCC) by cDNA microarray, we found that KIF23 was upregulated in HCC tissues. At present, much less is known about its expression and functions in tumor cells. In this work, we aimed to investigate the expression of KIF23 in HCC and the correlation between its expression and clinical features.Methods: Total RNA was extracted from 16 HCC and paired adjacent non-cancerous tissues. The expressions of the two KIF23 splice variants (KIF23 V1 and KIF23 V2) in normal and HCC tissues were determined by reverse transcriptase polymerase chain reaction (RT-PCR). Polyclonal antibody specific to KIF23 V1 was prepared, and the specificity of the antibody was confirmed by siRNA knockdown and Western blotting experiments. KIF23 protein expression in HCC was examined by immunohistochemistry staining with anti-KIF23 V1 or anti-KIF23 (commercially available for recognizing both KIF23 V1 and V2) antibodies, respectively. Univariate and Multivariate Cox regression analyses were used to determine the correlation between KIF23 protein expression and overall survival of HCC patients.Results: The two splicing variants of KIF23 mRNA were not detected in normal liver tissue by RT-PCR, but they were aberrantly expressed in HCC tissues. Immunohistochemistry staining with anti-KIF23 V1 antibody revealed that KIF23 V1 was mainly distributed in the nucleus, whereas the positive staining signals were predominantly in the cytoplasm when using anti-KIF23 antibody, suggesting that KIF23 V2 might localize in the cytoplasm of HCC cells. KIF23 V1 protein was detected in 57.6% (83/144) HCC patients and the mean H-score was 42, while KIF23 V2 was detected in 94.4% (135/143) HCC samples and the mean H-score was 68. Follow-up study showed that HCC patients with expression of KIF23 V1 had a longer 5-year survival (p=0.0052), however, expression of KIF23 V2 protein did not associate with 3- and 5-year survival.Conclusion: In this study we show for the first time that KIF23 V1 and V2 have different localizations in HCC cells. Furthermore, KIF23 V1 protein expression might be a marker of longer overall survival in HCC patients. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is one of the most frequent malignant tumors in the world. The only serological marker widely used for the diagnosis of HCC is alpha-fetoprotein (AFP). Despite that AFP is widely used for the diagnosis of HCC, it has a limit as a serological marker due to its low sensitivity and specificity. The human cervical cancer proto-oncogene 1 (HCCR-1) was previously reported as a new biomarker for HCC. To further evaluate the HCCR-1 as a biomarker for HCC, we conducted the prospective cohort study. We evaluated the significance of simultaneous measurement of 2 tumor markers in the diagnosis of HCC in China, Japan and Korea. Two markers for HCC, AFP and HCCR-1, were measured in the sera obtained from 1,338 patients at the time of initial diagnosis of HCC. Of the 1338 HCC patients, 616 (46%) and 686 (51.3%) were sero-positive for AFP and HCCR-1, respectively. The positive rate for HCC was increased up to 74.1% in combined use of AFP and HCCR-1. Many cases (54%) for AFP-negative HCC were positive for HCCR-1 and vice versa. More importantly, the diagnostic rate for small HCC (< 2 cm) was significantly improved in the combined analysis of AFP and HCCR-1 to 56.9% although it was only 40.1% and 23.4% in the single analysis of HCCR-1 and AFP, respectively. Our result suggests that the HCCR-1 could be an useful biomarker for HCC while the diagnostic rate could be significantly improved in the combined use of HCCR-1 and AFP. [ABSTRACT FROM AUTHOR]

Serum alpha fetoprotein (AFP) is the most widely used tumor marker in detecting patients with hepatocellular carcinoma (HCC). However, it has been indicated that HCCR-1 (human cervical cancer oncogene 1) might be supplementary to AFP in the detection. We conducted a prospective study in 120 normal and 524 liver disease patients to evaluate the significance of simultaneous measurement of 2 tumor markers (AFP and HCCR-1) in the diagnosis of HCC through the cohort study in Korea and China. We also performed immunohistochemical studies using 25 normal subjects (N), 32 liver cirrhosis (LC) and 116 HCC tissues. The sensitivities of AFP (20 ng/mL) and HCCR-1 (10 ng/mL) in HCC were 55.8% (164/294) and 44.2% (130/294), respectively. When AFP was combined with HCCR-1, sensitivities increased to 4.2% (N), 12.7% (chronic hepatitis; CH), 50.0% (LC), and 77.2% (HCC), respectively. Although there was no significant difference in the diagnostic rate for HCC between AFP and HCCR-1, many cases for AFP-negative HCC were positive for HCCR-1 and vice versa. Moreover, the combined use of AFP and HCCR-1 improved the diagnostic rate to 70.8% in small HCC (< 2 cm) and 81.6% in large HCC (&ges; 2 cm), respectively. AFP and HCCR-1 are independent markers. Our result suggests that the HCCR-1 could be an useful biomarker for HCC while the diagnostic rate could be significantly improved in the combined use of HCCR-1 and AFP. [ABSTRACT FROM AUTHOR]