Xueqin Chen

BCL-xL Is a Target Gene Regulated by Hypoxia-inducible Factor-1α

The transcription factor hypoxia-inducible factor-1α (HIF-1α) plays pivotal roles in physiology and pathophysiology. Constitutive or hypoxia-induced HIF-1α overexpression is observed in many types of cancers including prostate adenocarcinoma, in which it is associated with resistance to apoptosis and therapeutic agents. BCL-xL, a hypoxia-responsive, anti-apoptotic protein of the Bcl-2 family, is also overexpressed in prostate carcinoma and many other cancers. Despite this connection, whether BCL-xL expression is directly regulated by HIF-1α is not known. We used prostate cancer PC-3 cell with constitutive high HIF-1α level as a model to address this important question. We first generated prostate cancer PC-3 cells in which HIF-1α was stably knocked-down (HIF-KD) by using small interference RNA. BCL-xL was dramatically decreased in HIF-KD PC-3 cells, in parallel with sensitization to apoptosis with caspase-3 activation as well as decreased cell proliferation. We then demonstrated that HIF-1α directly regulated BCL-xL transcription by binding to a hypoxia-responsive element in the BCL-xL promoter (-865 to -847) by reporter gene assay, chromatin immunoprecipitation, and electrophoretic mobility shift and supershift assays. HIF-1α-dependent BCL-xL overexpression may be an important mechanism by which HIF-1α protects prostate cancer cells from apoptosis and leads to treatment resistance.

Survivin nuclear labeling index: a superior biomarker in superficial urothelial carcinoma of human urinary bladder

The caspase family proteases are key proapoptotic proteins while the inhibitor of apoptosis proteins (IAP) prevent apoptosis by antagonizing the caspases or other key proapoptotic proteins. Limited studies of IAPs suggested their deregulation contributed to urothelial neoplasia. However, the expression status and biologic or prognostic significance of the caspase and IAP family proteins in urothelial neoplasms is not clear. In the present study, we first systematically evaluated the expression profile of the major apoptosis regulators, including caspases (CASP3, 6, 7, 8, 9, 10, and 14), IAPs (survivin/BIRC5, CIAP1, CIAP2, XIAP, and LIVIN), APAF1, SMAC, and BCL2, as well as proliferation markers Ki67 and PHH3, in Ta/T1 human urinary bladder urothelial carcinomas and normal urothelium samples by immunohistochemistry. The analysis showed that survivin/BIRC5 nuclear labeling index (BIRC5-N), but not cytoplasmic staining, was the only apoptotic marker which correlated significantly with tumor grade, stage, and patient outcome. We further analyzed the prognostic value of BIRC5-N in 101 Ta/T1 urinary bladder urothelial carcinomas by univariate analysis, which showed that BIRC5-N as well as the more classical prognosticators (stage, grade, and Ki67 index) were of prognostic significance. However, multivariate analysis by Cox proportional hazard regression demonstrated BIRC5-N was a stronger prognosticator than tumor grade, stage, and Ki67 labeling index. BIRC5-N index of 8% or more predicted unfavorable disease-specific survival (relative risk (RR)=6.6, 95% confidence interval=1.6–26.7, P=0.0080) as well as progression-free survival (RR=4.4, 95% confidence interval=1.3–14.6, P=0.0151). We conclude that BIRC5-N is a superior biologic and prognostic marker for Ta/T1 urothelial carcinomas of urinary bladder.

MicroRNA-494-3p targets CXCR4 to suppress the proliferation, invasion, and migration of prostate cancer.

Although SDF‐1/CXCR4 pathway is a potential mechanism of tumor proliferation and progression, the mechanism of controlling CXCR4 expression is not fully understood. This study was to confirm that miR‐494‐3p might be a potentially post‐transcriptional regulator of CXCR4 and over‐expression of miR‐494 might suppress prostate cancer progression and metastasis.

Apoptosis and proliferation markers in diffusely infiltrating astrocytomas: profiling of 17 molecules.

Caspases and inhibitor of apoptosis proteins (IAPs) are antagonizing key apoptosis regulators. Limited studies of a few IAPs indicated their roles in astrocytomas. However, the overall expression status and significance of apoptosis regulators in astrocytomas is not clear. We examined the expression profile of the caspases (CASP3, 6, 7, 8, 9, 10, and 14), APAF1, SMAC, BCL2, the IAPs (BIRC5/survivin, CIAP1, CIAP2, XIAP, and LIVIN), and the proliferation markers Ki67 and PHH3 in 78 diffusely infiltrating astrocytomas and 24 normal brain samples by immunohistochemistry. Western blotting for major caspases and IAPs and reverse transcription-polymerase chain reaction analyses for IAPs were performed on a subset of 27 fresh samples. Our data showed BIRC5 nuclear labeling index (BIRC5-N) was the apoptosis marker most significantly different in World Health Organization grade II to IV astrocytomas and most strongly associated with proliferative activity. Expression level of other apoptosis-related proteins was modest or low in astrocytomas and did not correlate significantly with tumor grade or proliferation. Apoptosis regulators and proliferation markers were not detected in astrocytes of normal brain by immunostaining. This expression profile suggested involvement of apoptosis regulators in astrocytoma tumorigenesis, but tumor progression was more closely associated with proliferative advantages of which BIRC5 nuclear expression appeared to be a manifestation.

Caspases and inhibitor of apoptosis proteins in cutaneous and mucosal melanoma: expression profile and clinicopathologic significance

Malignant melanoma is characterized by apoptotic dysfunction, presumably due to abnormal expression of caspases and inhibitor of apoptosis proteins. However, the expression status and clinicopathologic significance of caspases and inhibitor of apoptosis proteins in cutaneous and particularly in mucosal melanomas have not been established. We investigated the expression of the major caspases (CASP3, 6, 7, 8, 9, and 10) and inhibitor of apoptosis proteins (survivin, CIAP1, CIAP2, XIAP, and Livin) by immunohistochemistry in 52 primary cutaneous and 25 mucosal melanomas, and 24 common nevi. Clinicopathologic and prognostic significance was investigated by statistical analysis. Our data showed that the significantly up-regulated inhibitor of apoptosis proteins in primary cutaneous and mucosal melanomas as compared with nevus (P < .01) were survivin, CIAP1, CIAP2, and Livin. Percentage of cases with positive caspase or IAP immunostaining was not significantly different between primary cutaneous and mucosal melanomas or between lower- and higher-stage melanomas (P > .05). Tumor location (cutaneous versus mucosal), stage, and positive cytoplasmic and nuclear survivin staining correlated significantly with prognosis by univariate analysis (P < .01). Multivariate analysis by Cox regression model showed that the most useful prognostic indicators were tumor location (cutaneous versus mucosal, relative risk = 6.021, 95% confidence interval = 2.623 approximately 13.821, P = .000), stage (relative risk = 4.129, 95% confidence interval = 1.817 approximately 9.383, P = .001), and nuclear survivin staining (relative risk = 3.383, 95% confidence interval = 1.137 approximately 10.008, P = .028).

Is there any prognostic impact of intraductal carcinoma of prostate in initial diagnosed aggressively metastatic prostate cancer

Intraductal carcinoma of prostate (IDC‐P) was usually found to be co‐exist with conventional aggressive prostate adenocarcinoma. The presence of IDC‐P was considered as an adverse pathological factor, which was associated with high Gleason score, large prostate volume and accelerated disease progression. However, no any information is available on the presence of IDC‐P diagnosed by needle biopsy in patients with metastatic prostate cancer. We investigated the incidence and prognostic value of intraductal carcinoma of prostate (IDC‐P) in initial diagnosed metastatic prostate cancer.

Expression and prognostic significance of survivin splice variants in diffusely infiltrating astrocytoma

Background Alternative splicing of survivin (BIRC5) pre-mRNA generates the common isoform survivin and five additional splice variants: survivin2B, survivinΔEx3, survivin2α, survivin3B and survivin3α. Although the common isoform survivin has been shown to be involved in tumourigenesis and progression of various tumours, including diffusely infiltrating astrocytoma, the expression of other survivin splice variants in astrocytoma has not been fully investigated. Aims To evaluate the expression status and particularly prognostic significance of survivin splice variants in diffusely infiltrating astrocytoma. Methods mRNA expression of the six survivin variants in 73 diffusely infiltrating astrocytoma and 18 normal brain tissue samples was investigated by using reverse transcription-PCR (RT-PCR), and the total survivin protein expression by western analysis and immunohistochemistry. Association of survivin and its splice variants with tumour grade and prognosis was examined by statistical and survival analysis. Results The survivin, survivinΔEx3, survivin2B and survivin2α splice variants were significantly elevated in diffusely infiltrating astrocytoma, and were barely detectable or not detectable at all in normal brain tissue. Survivin3B and survivin3α were not detected in these samples. The positive rates of the expressed four variants increased with astrocytoma grade. Significantly, expression of these splice variants was associated with much poorer disease-specific and progression-free survival (Kaplan–Meier analysis, p≤0.002). Cox regression model further indicated survivin2α mRNA expression and nuclear survivin immunostaining to be significant independent negative prognostic factors. Conclusions The survivin, survivinΔEx3, survivin2B and survivin2α splice variants were significantly elevated in astrocytoma, and were associated with tumour grade and poorer prognosis.

The presence and clinical implication of intraductal carcinoma of prostate in metastatic castration resistant prostate cancer

Intraductal carcinoma of prostate (IDC‐P) is always underestimated pathological pattern in prostate cancer and its role is still unclear in castration resistant prostate cancer (CRPC). This study was conducted to investigate the presence and the roles of IDC‐P in patients with metastatic CRPC.

Long noncoding RNA ZEB1-AS1 epigenetically regulates the expressions of ZEB1 and downstream molecules in prostate cancer

BackgroundEmerging studies show that long noncoding RNAs (lncRNAs) play important roles in carcinogenesis and cancer progression. The lncRNA ZEB1 antisense 1 (ZEB1-AS1) derives from the promoter region of ZEB1 and we still know little about its expressions, roles and mechanisms.MethodsRACE was used to obtain the sequence of ZEB1-AS1. RNA interference was used to decrease ZEB1-AS1 expression. Adenovirus expression vector was used to increase ZEB1-AS1 expression. CHIP and RIP were used to detect the epigenetic mechanisms by which ZEB1-AS1 regulated ZEB1. CCK8 assay, wound healing assay and transwell assay were used to measure proliferation and migration of prostate cancer cells.ResultsIn this study, in prostate cancer cells, we found that RNAi-mediated downregulation of ZEB1-AS1 induced significant ZEB1 inhibition while artificial overexpression of ZEB1-AS1 rescued ZEB1 expression, which means that ZEB1-AS1 promotes ZEB1 expression. Also, ZEB1-AS1 indirectly inhibited miR200c, the well-known target of ZEB1, and upregulated miR200c’s target BMI1. Mechanistically, ZEB1-AS1 bound and recruited histone methyltransferase MLL1 to the promoter region of ZEB1, induced H3K4me3 modification therein, and activated ZEB1 transcription. Biologically, ZEB1-AS1 promoted proliferation and migration of prostate cancer cells.ConclusionsCollectively, ZEB1-AS1 functions as an oncogene in prostate cancer via epigenetically activating ZEB1 and indirectly regulating downstream molecules of ZEB1.

Adrenal and Extra-Adrenal Nonfunctioning Composite Pheochromocytoma/Paraganglioma with Immunohistochemical Ectopic Hormone Expression: Comparison of Two Cases

Adrenal composite pheochromocytoma is rare, most of which is functional, and extra-adrenal composite paraganglioma is extremely rare. We describe and compare the clinicopathological and immunohistochemical features of a retroperitoneal extra-adrenal composite paraganglioma and an adrenal composite pheochromocytoma. Both tumors were nonfunctioning and laboratory tests revealed no biochemical abnormalities. Both tumors were composed of typical paraganglioma/pheochromocytoma closely admixed with ganglioneuroma component. In addition to typical immunohistochemical phenotypes characteristic of each component, both tumors showed focal staining of somatostatin, and the adrenal tumor was also regionally positive for insulin and prolactin. Despite this aberrant immunohistochemical expression, relevant clinical symptoms or laboratory abnormalities were absent. These tumors serve to exemplify the extremely rare occurrences of clinically silent, nonfunctioning composite pheochromocytoma or paraganglioma with aberrant expression of hormones.