Topoisomerase inhibitors modulate gene expression of B-cell translocation gene 2 and prostate specific antigen in prostate carcinoma cells

The DHODH inhibitor teriflunomide impedes cell proliferation and enhances chemosensitivity to daunorubicin (DNR) in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological tumor that requires novel treatment strategies, especially for relapsed/refractory cases. Dihydroorotate dehydrogenase (DHODH), a key enzyme in the de novo pyrimidine synthesis pathway, has been identified as a potential target for tumors. Besides, Teriflunomide (TRF) is a DHODH inhibitor with anticancer effects; however, its role in T-ALL remains poorly understood. Here, we investigated the potential anticancer effects of TRF on T-ALL cells, and the results showed that TRF inhibited cell proliferation, caused S-phase cell cycle arrest, and promoted apoptosis of T-ALL (MOLT4 and JURKAT) cell lines. In addition, TRF reduced the infiltration capacity of T-ALL cells in T-ALL xenograft mice while up-regulating the expression of P53 and BTG2. The BTG2 knockdown significantly attenuated the inhibitory effect of TRF on cellular growth and suppressed the TRF-mediated elevated expression of P53 in T-ALL cells. Moreover, combined treatment with TRF and daunorubicin (DNR) significantly reduced cell viability and promoted apoptosis in DNR-resistant T-ALL cells. Our study provides valuable insights into the critical role of TRF in treating T-ALL while increasing the sensitivity of DNR-resistant T-ALL cells to DNR.

Antitumor Activity of NLG207 (Formerly CRLX101) in Combination with Enzalutamide in Preclinical Prostate Cancer Models

Effective treatments for patients with metastatic castration-resistant prostate cancer following disease progression on enzalutamide are currently an unmet clinical need. Simultaneous inhibition of the hypoxia-inducible factor (HIF)-1α and androgen receptor (AR) pathways has been previously shown to overcome enzalutamide resistance in vitro Combination treatment with NLG207, a nanoparticle-drug conjugate of camptothecin and inhibitor of HIF-1α, and enzalutamide was evaluated in preclinical prostate cancer models of enzalutamide resistance. The effect of NLG207 and enzalutamide on average tumor volume and tumor re-growth after 3 weeks of treatment was evaluated in vivo using the subcutaneous 22Rv1 xenograft and castrated subcutaneous VCaP xenograft models. Correlative assessments of antitumor activity were evaluated in vitro using cell proliferation and qPCR assays. NLG207 8 mg/kg alone and in combination with enzalutamide reduced average tumor volume by 93% after 3 weeks of treatment (P < 0.05) in comparison with vehicle control in the subcutaneous 22Rv1 xenograft model. Notably, the addition of NLG207 also enhanced the efficacy of enzalutamide alone in the castrated subcutaneous VCaP xenograft model, decreasing the median rate of tumor growth by 51% (P = 0.0001) in comparison with enzalutamide alone. In vitro assessments of cell proliferation and gene expression further demonstrated antitumor activity via AR-HIF-1α crosstalk inhibition. Combination treatment with NLG207 and enzalutamide was shown to be effective in preclinical prostate cancer models of enzalutamide resistance. Clinical investigation of this treatment combination is ongoing (NCT03531827).

Celastrol: A Review of Useful Strategies Overcoming its Limitation in Anticancer Application

Celastrol, a natural bioactive ingredient derived from Tripterygium wilfordii Hook F, exhibits significant broad-spectrum anticancer activities for the treatment of a variety of cancers including liver cancer, breast cancer, prostate tumor, multiple myeloma, glioma, etc. However, the poor water stability, low bioavailability, narrow therapeutic window, and undesired side effects greatly limit its clinical application. To address this issue, some strategies were employed to improve the anticancer efficacy and reduce the side-effects of celastrol. The present review comprehensively focuses on the various challenges associated with the anticancer efficiency and drug delivery of celastrol, and the useful approaches including combination therapy, structural derivatives and nano/micro-systems development. The specific advantages for the use of celastrol mediated by these strategies are presented. Moreover, the challenges and future research directions are also discussed. Based on this review, it would provide a reference to develop a natural anticancer compound for cancer treatment.

Tumor suppressors BTG1 and BTG2: Beyond growth control

Since the identification of B‐cell translocation gene 1 (BTG1) and BTG2 as antiproliferation genes more than two decades ago, their protein products have been implicated in a variety of cellular processes including cell division, DNA repair, transcriptional regulation and messenger RNA stability. In addition to affecting differentiation during development and in the adult, BTG proteins play an important role in maintaining homeostasis under conditions of cellular stress. Genomic profiling of B‐cell leukemia and lymphoma has put BTG1 and BTG2 in the spotlight, since both genes are frequently deleted or mutated in these malignancies, pointing towards a role as tumor suppressors. Moreover, in solid tumors, reduced expression of BTG1 or BTG2 is often correlated with malignant cell behavior and poor treatment outcome. Recent studies have uncovered novel roles for BTG1 and BTG2 in genotoxic and integrated stress responses, as well as during hematopoiesis. This review summarizes what is currently known about the roles of BTG1 and BTG2 in these and other cellular processes. In addition, we will highlight the molecular mechanisms and biological consequences of BTG1 and BTG2 deregulation during cancer progression and elaborate on the potential clinical implications of these findings.

BTG2 is a tumor suppressor gene upregulated by p53 and PTEN in human bladder carcinoma cells

Although widely deemed as a tumor suppressor gene, the role of B-cell translocation gene 2 (BTG2) in bladder cancer is still inconclusive. We investigated the role and regulatory mechanism of BTG2 in bladder cancer. BTG2 expression in human bladder tissues was determined by RT-qPCR and immunoblotting assays. Expressions of BTG2 and PTEN in bladder carcinoma cells were determined by immunoblotting, RT-qPCR, or reporter assays. The ³ H-thymidine incorporation assay, flow cytometry, and the xenograft animal model were used to determine the cell growth. BTG2 expression was lower in human bladder cancer tissues than normal bladder tissues. Highly differentiated bladder cancer cells, RT4, expressed higher BTG2 than the less-differentiated bladder cancer cells, HT1376 and T24. Overexpression of BTG2 in T24 cells inhibited cell growth in vitro and in vivo. Camptothecin and doxorubicin treatments in RT-4 cells or transient overexpression of p53 into p53-mutant HT1376 cells induced p53 and BTG2 expression. Further reporter assays with site-mutation of p53 response element from GGGAAAGTCC to GGAGTCC within BTG2 promoter area showed that p53-induced BTG2 gene expression was dependent on the p53 response element. Ectopic PTEN overexpression in T24 cells blocked the Akt signal pathway which attenuated cell growth via upregualtion of BTG2 gene expression, while reverse effect was found in PTEN-knockdown RT-4 cells. PTEN activity inhibitor (VO-OHpic) treatment decreased BTG2 expression in RT-4 and PTEN-overexpressed T24 cells. Our results suggested that BTG2 functioned as a bladder cancer tumor suppressor gene, and was induced by p53 and PTEN. Modulation of BTG2 expression seems a promising way to treat human bladder cancer.

MART-10 represses cholangiocarcinoma cell growth and high vitamin D receptor expression indicates better prognosis for cholangiocarcinoma

Cholangiocarcinoma (CCA) is a devastating disease due to no effective treatments available. Since the non-mineral functions of vitamin D emerges, 1α,25(OH)₂D₃, the active form of vitamin D, has been applied in anti-cancer researches. In this study, we demonstrated that both the 1α,25(OH)₂D₃ analog, MART-10, and 1α,25(OH)₂D₃ possessed anti-growth effect on human CCA cells with MART-10 much more potent than 1α,25(OH)₂D₃. The growth inhibition of both drugs were mediated by induction of G0/G1 cell cycle arrest through upregulation of p27 and downregulation of CDK4, CDK6, and cyclin D3. Human neutrophil gelatinase associated lipocalin (NGAL) was found to be involved in 1α,25(OH)₂D₃ and MART-10 meditated growth inhibition for CCA as knockdown of NGAL decreased Ki-67 expression in SNU308 cells and rendered SNU308 cells less responsive to 1α,25(OH)₂D₃ and MART-10 treatment. Vitamin D receptor (VDR) knockdown partly abolished MART-10-induced inhibition of NGAL and cell growth in SNU308 cells. The xenograft animal study demonstrated MART-10 could effectively repressed CCA growth in vivo without inducing obvious side effects. The IHC examination of human CCA specimen for VDR revealed that higher VDR expression was linked with better prognosis. Collectively, our results suggest that MART-10 could be a promising regimen for CCA treatment.

25(OH)D Is Effective to Repress Human Cholangiocarcinoma Cell Growth through the Conversion of 25(OH)D to 1α,25(OH)₂D₃

Cholangiocarcinoma (CCA) is a devastating disease without effective treatments. 1α,25(OH)₂D₃, the active form of Vitamin D, has emerged as a new anti-cancer regimen. However, the side effect of hypercalcemia impedes its systemic administration. 25(OH)D is biologically inert and needs hydroxylation by CYP27B1 to form 1α,25(OH)₂D₃, which is originally believed to only take place in kidneys. Recently, the extra-renal expression of CYP27B1 has been identified and in vitro conversion of 25(OH)D to 1α,25(OH)₂D₃ has been found in some cancer cells with CYP27B1 expression. In this study, CYP27B1 expression was demonstrated in CCA cells and human CCA specimens. 25(OH)D effectively represses SNU308 cells growth, which was strengthened or attenuated as CYP27B1 overexpression or knockdown. Lipocalcin-2 (LCN2) was also found to be repressed by 25(OH)D. After treatment with 800 ng/mL 25(OH)D, the intracellular 1α,25(OH)₂D₃ concentration was higher in SNU308 cells with CYP27B1 overexpression than wild type SNU308 cells. In a xenograft animal experiment, 25(OH)D, at a dose of 6 μg/kg or 20 μg/kg, significantly inhibited SNU308 cells’ growth without inducing obvious side effects. Collectively, our results indicated that SNU308 cells were able to convert 25(OH)D to 1α,25(OH)₂D₃ and 25(OH)D CYP27B1 gene therapy could be deemed as a promising therapeutic direction for CCA.

Prostate-derived ets factor represses tumorigenesis and modulates epithelial-to-mesenchymal transition in bladder carcinoma cells

Prostate-derived Ets (E-twenty six) factor (PDEF), an epithelium-specific member of the Ets family of transcription factors, has been shown to play a role in suppressing the development of many epithelium-derived cancers such as prostate and breast cancer. It is not clear, however, whether PDEF is involved in the development or progression of bladder cancer. In a comparison between normal urothelium and bladder tumor tissue, we identified significant decreases of PDEF in the tumor tissue. Further, the immunohistochemistry assays indicated a significantly higher immunostaining of PDEF in low-grade bladder tumors. Additionally, the highly differentiated transitional-cell bladder carcinoma RT-4 cells expressed significantly more PDEF levels than the bladder carcinoma HT1376 and the T24 cells. Ectopic overexpression of PDEF attenuated proliferation, invasion, and tumorigenesis of bladder carcinoma cells in vitro and in vivo. PDEF enhanced the expression levels of mammary serine protease inhibitor (MASPIN), N-myc downstream regulated gene 1 (NDRG1), KAI1, and B-cell translocation gene 2 (BTG2). PDEF modulated epithelial-mesenchymal-transition (EMT) by upregulating E-cadherin expression and downregulating the expression of N-cadherin, SNAIL, SLUG, and vimentin, leading to lower migration and invasion abilities of bladder carcinoma cells. Filamentous actin (F-actin) polarization and remodeling were observed in PDEF-knockdown RT-4 cells. Our results suggest that PDEF gene expression is associated with the extent of bladder neoplasia and PDEF modulated the expressions of EMT-related genes. The induction of BTG2, NDRG1, MASPIN, and KAI1 gene expressions by PDEF may explain the inhibitory functions of PDEF on the proliferation, invasion, and tumorigenesis in bladder carcinoma cells.

Monitoring of prostate cancer growth and metastasis using a PSA luciferase report plasmid in a mouse model

OBJECTIVE

To construct a PSA luciferase report plasmid and monitor the growth and metastasis of prostate cancer after emasculation in SCID mice.

METHODS

PSA promoter sequence and luciferase gene were amplified by PCR and subsequently inserted into pZsGreen1-1 vector to construct pPSA-FL-Luc vector. LNCaP cells that were stably transfected with pPSA-FL-Luc were used to establish a SCID mouse xenograft model. Then, the growth and metastasis of prostate cancer were monitored via living imaging.

RESULTS

We successfully constructed a PSA luciferase plasmid, pPSA-FL-Luc. DHT enhanced luciferase activity in a concentration-dependent manner in 293T cells with pPSA-FL-Luc transfection. Prostate cancer SCID mouse model was established with pPSA-FL-Luc transfected LNCaP cells. In tumor bearing mice with or without emasculation, pPSA-FL-Luc plasmid was applied to monitored tumor growth and metastasis based on bioluminescence imaging.

CONCLUSIONS

We construct a pPSA-FL-Luc plasmid, which stably expresses luciferase and can be applied to monitor tumor development in a prostate SCID mouse model.

Cisplatin modulates B-cell translocation gene 2 to attenuate cell proliferation of prostate carcinoma cells in both p53-dependent and p53-independent pathways

Cisplatin is a widely used anti-cancer drug. The B-cell translocation gene 2 (BTG2) is involved in the cell cycle transition regulation. We evaluated the cisplatin effects on prostate cancer cell proliferation and the expressions of BTG2, p53, androgen receptor (AR) and prostate specific antigen (PSA) in prostate carcinoma, p53 wild-type LNCaP or p53-null PC-3, cells. Cisplatin treatments attenuated cell prostate cancer cell growth through inducing Go/G1 cell cycle arrest in lower concentration and apoptosis at higher dosage. Cisplatin treatments enhanced p53 and BTG2 expression, repressed AR and PSA expression, and blocked the activation of androgen on the PSA secretion in LNCaP cells. BTG2 knockdown in LNCaP cells attenuated cisplatin-mediated growth inhibition. Cisplatin enhanced BTG2 gene expression dependent on the DNA fragment located within -173 to -82 upstream of BTG2 translation initiation site in prostate cancer cells. Mutation of the p53 response element from GGGCAGAGCCC to GGGCACC or mutation of the NFκB response element from GGAAAGTCC to GGAAAGGAA by site-directed mutagenesis abolished the stimulation of cisplatin on the BTG2 promoter activity in LNCaP or PC-3 cells, respectively. Our results indicated that cisplatin attenuates prostate cancer cell proliferation partly mediated by upregulation of BTG2 through the p53-dependent pathway or p53-independent NFκB pathway.