YooHyun Song

N-myc downstream regulated gene-1/Cap43 may play an important role in malignant progression of prostate cancer, in its close association with E-cadherin

N-myc downstream regulated gene-1 (NDRG1)/Cap43 plays an important role in tumor progression and metastases in many kinds of cancers. Recently, it was reported that NDRG1/Cap43 is involved in the aggressiveness of prostate cancer and also that its expression is associated with the expression of E-cadherin in prostate carcinoma cell lines. In the current study, to elucidate the functional and pathologic roles of NDRG1/Cap43 in prostate cancer, we investigated whether the expression of NDRG1/Cap43 is associated with the clinicopathologic parameters of prostate cancer or E-cadherin expression. NDRG1/Cap43 expression and E-cadherin expression were examined immunohistochemically in 148 patients with prostate cancer. We investigated the correlation between membranous or cytoplasmic expression of NDRG1/Cap43 and E-cadherin and evaluated the prognostic or clinicopathologic significance of the expression of NDRG1/Cap43. The patients with decreased NDRG1/Cap43 membranous expression showed significantly lower disease-free survival rates compared with the patients with preserved NDRG1/Cap43 membranous expression. Decreased membranous and high cytoplasmic NDRG1/Cap43 expression was also correlated with a higher Gleason score. A significant correlation was observed between NDRG1/Cap43 membranous expression and E-cadherin membranous expression (r = 0.7130; P < .0001) and between NDRG1/Cap43 cytoplasmic expression and E-cadherin cytoplasmic expression (r = 0.5847; P < .0001). Decreased NDRG1/Cap43 membranous expression had a significant impact on patient disease-free survival in multivariate analysis (P = .0175). NDRG1/Cap43 could be a novel marker for malignant progression and poor prognosis in prostate cancer, plausibly in its close association with the down-regulation of E-cadherin expression.

Foxo3a Suppression of Urothelial Cancer Invasiveness through Twist1, Y-Box–Binding Protein 1, and E-Cadherin Regulation

Purpose: Invasion and metastasis are key steps in the progression of urothelial cancer (UC) into a critical disease. Foxo3a is a member of the Foxo transcription factor family that modulates the expression of various genes. We aimed to elucidate the role of Foxo3a in UC invasion. Experimental Design: Foxo3a mRNA and protein expressions in UC samples were investigated by gene expression assays and immunohistochemistry, respectively. Foxo3a expression was compared with clinicopathologic characteristics and patient prognoses based on UC samples. Quantitative real-time polymerase chain reaction, Western blotting, and migration assays were also conducted in UC cells. Results: Foxo3a expression decreased in invasive UC; patients with low Foxo3a expression had poor disease-free survival, cancer-specific survival, and overall survival; Foxo3a knockdown in UC cells increased cellular motility. Foxo3a negatively regulated Twist1 and Y-box–binding protein 1 (YB-1), and positively regulated E-cadherin in KK47 and TCCsup cells that expressed Twist1, but not in T24 cells that did not express Twist1. Foxo3a-associated acetyltransferase p300 and Foxo3a acetylation status also affected UC motility. Conclusion: The results of this study indicate that Foxo3a regulates motility of UC through negative regulation of Twist1 and YB-1, and through positive regulation of E-cadherin. This suggests that Foxo3a could act as an independent prognostic factor in UC and could represent a promising molecular target for cancer therapeutics. Clin Cancer Res; 16(23); 5654–63. ©2010 AACR.

Y-box binding protein-1 promotes castration-resistant prostate cancer growth via androgen receptor expression

The androgen receptor (AR) is well known to play a central role in the pathogenesis of prostate cancer (PCa). In several studies, AR was overexpressed in castration-resistant PCa (CRPC). However, the mechanism of AR overexpression in CRPC is not fully elucidated. Y-box binding protein-1 (YB-1) is a pleiotropic transcription factor that is upregulated in CPRC. We aimed to elucidate the role of YB-1 in castration resistance of PCa and identify therapeutic potential of targeting YB-1. Using immunohistochemistry, we found that nuclear YB-1 expression significantly correlated with the Gleason score and AR expression in PCa tissues. In PCa cells, YB-1 regulated AR expression at the transcriptional level. Furthermore, YB-1 expression and nuclear localization were upregulated in CRPC cells. Overexpression of AR, as well as YB-1, conferred castration-resistant growth in LNCaP and 22Rv1 cells. Conversely, knocking down YB-1 resulted in suppressed cell growth and induced apoptosis, which was more efficient than knocking down AR in LNCaP cells. In other types of PCa cells, such as CRPC cells, knocking down YB-1 resulted in a significant reduction of cell growth. In conclusion, these findings suggested that YB-1 induces castration resistance in androgen-dependent PCa cells via AR expression. Thus, YB-1 may be a promising therapeutic target for PCa, as well as CRPC.

The important role of glycine N-methyltransferase in the carcinogenesis and progression of prostate cancer

Glycine N-methyltransferase (GNMT) has a role in the metabolism of methionine as well as in gluconeogenesis. It has recently been reported that the GNMT gene acts as a tumor-susceptible gene. However, little is known about the specific function of GNMT in carcinogenesis and malignant progression. To better our understanding of the function of GNMT in prostate cancer, we used siRNAs to examine the effects of GNMT knockdown on cell proliferation and the cell cycle. In addition, the relation between immunohistochemical GNMT expression and clinicopathologic parameters was investigated in 148 prostate cancer tissues. Here, we show that siRNA-mediated GNMT knockdown results in an inhibition of proliferation, and induces G1 arrest and apoptosis in prostate cancer cell lines. Moreover, high cytoplasmic GNMT expression was also correlated with a higher Gleason score (P<0.001) and higher pT stage (P=0.027). The patients with high GNMT cytoplasmic expression showed significantly lower disease-free survival rates than patients with low expression (P<0.001). High GNMT cytoplasmic expression had a significant impact on patient disease-free survival in multivariate analysis (P=0.005). This is the first investigation to reveal the novel finding that GNMT may have an important role in promoting prostate cancer cell growth via the regulation of apoptosis and contribute to the progression of prostate cancer. The modulation of GNMT expression or function may be a strategy for developing novel therapeutics for prostate cancer. GNMT may represent a novel marker of malignant progression and poor prognosis in prostate cancer.

Twist1 and Y‐box‐binding protein‐1 promote malignant potential in bladder cancer cells

What’s known on the subject? and What does the study add?

Antioxidant Therapy Alleviates Oxidative Stress by Androgen Deprivation and Prevents Conversion From Androgen Dependent to Castration Resistant Prostate Cancer

PURPOSE Prostate cancer progression from androgen dependence to castration resistance results at least in part from oxidative stress induced by androgen deprivation therapy. We elucidated the state and the role of oxidative stress induced by androgen deprivation therapy and the possibility of antioxidant therapy in human prostate cancer. MATERIALS AND METHODS We investigated 4-HNE (4-hydroxy-2-nonenal histidine adduct) staining, and Twist1, YB-1 and androgen receptor expression by immunohistochemistry in prostate cancer samples treated with or without neoadjuvant androgen deprivation therapy. Intracellular reactive oxygen species and protein expression were examined by CM-H(2)DCFDA and Western blot analysis, respectively. A cell proliferation assay and a mouse xenograft model were used to assess tumor growth. RESULTS Androgen deprivation therapy increased oxidative stress, as shown by 4-HNE staining in human prostate cancer tissue. Twist1 and YB-1 expression was up-regulated by androgen deprivation, resulting in androgen receptor over expression. In LNCaP and 22Rv1 cells androgen deprivation increased intracellular reactive oxygen species and evoked Twist1, YB-1 and androgen receptor over expression, resulting in cell growth in a castration resistant manner. Growth was alleviated by N-acetyl-cysteine, an electrophile that supports glutathione production. N-acetyl-cysteine also decreased LNCaP and 22Rv1 tumor growth in castrated and noncastrated mice. CONCLUSIONS Androgen deprivation therapy induced oxidative stress in in vitro and human prostate cancer. Antioxidant therapy using N-acetyl-cysteine appears to be a promising therapeutic modality for prostate cancer.

Interaction between docetaxel resistance and castration resistance in prostate cancer: implications of Twist1, YB-1, and androgen receptor.

Taxanes, including docetaxel, are currently the only cytotoxic chemotherapeutic agents proven to confer survival benefit in patients with castration‐resistant prostate cancer (CRPC). However, the merits of taxanes remain modest, and efforts are needed to improve their therapeutic efficacy.

Mutual regulation between Raf/MEK/ERK signaling and Y-box-binding protein-1 promotes prostate cancer progression

Purpose: Y-box–binding protein-1 (YB-1) is known to conduct various functions related to cell proliferation, anti-apoptosis, epithelial–mesenchymal transition, and castration resistance in prostate cancer. However, it is still unknown how YB-1 affects cancer biology, especially its correlations with the mitogen-activated protein kinase (MAPK) signaling pathway. Therefore, we aimed to examine the interaction between YB-1 and the MAPK pathway in prostate cancer. Experimental Design: Quantitative real-time PCR, Western blotting, and co-immunoprecipitation assay were conducted in prostate cancer cells. YB-1, phosphorylated YB-1 (p-YB-1), and ERK2 protein expressions in 165 clinical specimens of prostate cancer were investigated by immunohistochemistry. YB-1, p-YB-1, and ERK2 nuclear expressions were compared with clinicopathologic characteristics and patient prognoses. Results: EGF upregulated p-YB-1, whereas MEK inhibitor (U0126, PD98059) decreased p-YB-1. Inversely, silencing of YB-1 using siRNA decreased the expression of ERK2 and phosphorylated MEK, ERK1/2, and RSK. Furthermore, YB-1 interacted with ERK2 and Raf-1 and regulated their expressions, through the proteasomal pathway. Immunohistochemical staining showed a significant correlation among the nuclear expressions of YB-1, p-YB-1, and ERK2. The Cox proportional hazards model revealed that high ERK2 expression was an independent prognostic factor [HR, 7.947; 95% confidence interval (CI), 3.527–20.508; P < 0.0001]. Conclusion: We revealed the functional relationship between YB-1 and MAPK signaling and its biochemical relevance to the progression of prostate cancer. In addition, ERK2 expression was an independent prognostic factor. These findings suggest that both the ERK pathway and YB-1 may be promising molecular targets for prostate cancer diagnosis and therapeutics. Clin Cancer Res; 19(17); 4638–50. ©2013 AACR.

Mitochondrial p32/C1QBP is highly expressed in prostate cancer and is associated with shorter prostate-specific antigen relapse time after radical prostatectomy

Mitochondria are key organelles for ATP production and apoptosis. Therefore, impairment of mitochondria can modulate or accelerate cancer progression. p32, originally identified as a pre‐mRNA splicing factor SF2/ASF‐associated protein, is localized predominantly in the mitochondrial matrix and involved in mitochondria respiration. Recently, p32 was implicated in apoptosis and resultantly cancer progression. However, little is known about the expression and function of p32 in human tumors including prostate cancer. Here, we investigated the expression of p32 in 148 prostate carcinoma tissues by immunohistochemistry and found a positive correlation of p32 expression to clinicopathological parameters including follow‐up data. p32 is highly expressed in prostate tumor samples and its expression is significantly associated with the Gleason score, pathological stage and relapse. For localized cancers, high p32 is a strong and independent predictor of clinical recurrence in multivariate analysis (P = 0.01). In addition, p32 is overexpressed in the prostate cancer cell lines examined. The selective knockdown of p32 by RNA interference inhibits the growth of prostate cancer cell lines but not of a non‐cancerous cell line. The p32 RNA interference decreases cyclin D1, increases p21 expression and causes a G1/S cell cycle arrest in prostate cancer cells. These data suggest that p32 is critical for prostate cancer cell proliferation and may be a novel marker of clinical progression in prostate cancer. (Cancer Sci 2011; 102: 639–647)

Inhibition of Protein Kinase C/Twist1 Signaling Augments Anticancer Effects of Androgen Deprivation and Enzalutamide in Prostate Cancer

Purpose: The progression of prostate cancer to metastatic and castration-resistant disease represents a critical step. We previously showed that the transcription factor Twist1, which promotes epithelial–mesenchymal transition, was involved in castration-resistant progression. Similarly, protein kinase C (PKC) has been implicated in both metastatic progression and castration resistance in prostate cancer. Experimental Design: In this study, we aimed to elucidate the role of PKC/Twist1 signaling in castration resistance, and to apply this information to the development of a novel therapeutic concept using PKC inhibitor Ro31-8220 against prostate cancer using various prostate cancer cell lines. Results: Androgen deprivation and the next-generation antiandrogen enzalutamide induced PKC activation and Twist1 expression, which were reversed by the PKC inhibitor Ro31-8220. Ro31-8220 suppressed cell proliferation in androgen-dependent prostate cancer LNCaP cells, which was augmented by its combination with androgen deprivation or enzalutamide. The favorable anticancer effects of the combination of Ro31-8220 and enzalutamide were also observed in castration-resistant C4-2 and 22Rv1 cells. Furthermore, PKC phosphorylation was elevated in castration-resistant and enzalutamide-resistant cells compared with their parental cells, leading to persistent sensitivity to Ro-31-8220 in castration- and enzalutamide-resistant cells. Conclusions: Taken together, these findings indicate that PKC/Twist1 signaling contributes to castration resistance as well as enzalutamide resistance in prostate cancer, and suggest that therapeutics targeting PKC/Twist1 signaling, such as PKC inhibitors, represent a promising novel therapeutic strategy for prostate cancer, especially castration-resistant prostate cancer, when combined with enzalutamide. Clin Cancer Res; 20(4); 951–61. ©2013 AACR.