p53 alone or in combination with antisense cyclin D1 induces apoptosis and reduces tumor size in human melanoma

Extraction Optimization, Structural Characterization, and Anti-Hepatoma Activity of Acidic Polysaccharides From Scutellaria barbata D. Don

The Chinese medicinal herb Scutellaria barbata D. Don has antitumour effects and is used to treat liver cancer in the clinic. S. barbata polysaccharide (SBP), one of the main active components extracted from S. barbata D. Don, exhibits antitumour activity. However, there is still a lack of research on the extraction optimization, structural characterization, and anti-hepatoma activity of acidic polysaccharides from S. barbata D. Don. In this study, the optimal extraction conditions for SBP were determined by response surface methodology (RSM): the material-liquid ratio was 1:25, the extraction time was 2 h, and the extraction temperature was 90°C. Under these conditions, the average extraction efficiency was 3.85 ± 0.13%. Two water-soluble polysaccharides were isolated from S. barbata D. Don, namely, SBP-1A and SBP-2A, these homogeneous acidic polysaccharide components with average molecular weights of 1.15 × 10⁵ Da and 1.4 × 10⁵ Da, respectively, were obtained at high purity. The results showed that the monosaccharide constituents of the two components were fucose, galactosamine hydrochloride, rhamnose, arabinose, glucosamine hydrochloride, galactose, glucose, xylose, and mannose; the molar ratio of these constituents in SBP-1A was 0.6:0.3:0.6:30.6:3.3:38.4:16.1:8:1.4, and that in SBP-2A was 0.6:0.5:0.8:36.3:4.4:42.7:9.2:3.6:0.7. In addition, SBP-1A and SBP-2A contained uronic acid and β-glucan, and the residue on the polysaccharide was mainly pyranose. The in vitro results showed that the anti-hepatoma activity of SBP-2A was better than that of SBP-1A and SBP. In addition, SBP-2A significantly enhanced HepG2 cell death, as cell viability was decreased, and SBP-2A induced HepG2 cell apoptosis and blocked the G1 phase. This phenomenon was coupled with the upregulated expression of P53 and Bax/Bcl-2 ratio, as well as the downregulated expression of the cell cycle-regulating protein cyclinD1, CDK4, and Bcl-2 in this study. Further analysis showed that 50 mg/kg SBP-2A inhibited the tumour growth in H22 tumour-bearing mice, with an average inhibition rate of 40.33%. Taken together, SBP-2A, isolated and purified from S. barbata showed good antitumour activity in vivo and in vitro, and SBP-2A may be a candidate drug for further evaluation in cancer prevention. This study provides insight for further research on the molecular mechanism of the anti-hepatoma activity of S. barbata polysaccharide.

Star-PAP controls HPV E6 regulation of p53 and sensitizes cells to VP-16

Cervical cancer is the most common genital malignancy and the high-risk human papillomaviruses (HPV type 16, 18 and 31, and so on) are major agents for its cause. A key switch for the onset of cervical cancers by HPVs is the cellular degradation of the tumor-suppressor p53 that is mediated by the HPV-generated E6 protein. E6 forms a complex with the E3 ubiquitin-ligase E6-associated protein (E6AP) leading to p53 degradation. The components that control E6 expression and the mechanisms for regulation of the expression in host cells remain undefined. Here we show that the nuclear noncanonical poly(A) polymerase (PAP) speckle targeted PIPKIα regulated PAP (Star-PAP) controls E6 mRNA polyadenylation and expression and modulates wild-type p53 levels as well as cell cycle profile in high-risk HPV-positive cells. In the absence of Star-PAP, treatment of cells with the chemotherapeutic drug VP-16 dramatically reduced E6 and increased p53 levels. This diminished both cell proliferation and anchorage-independent growth required for cancer progression, indicating a synergism between VP-16 treatment and the loss of Star-PAP. This identifies Star-PAP as a potential drug target for the treatment of HPV-positive cancer cells. These data provide a mechanistic basis for increasing the sensitivity and efficiency of chemotherapy in the treatment of cancers that have low levels of wild-type p53.

The effect of miR-338-3p on HBx deletion-mutant (HBx-d382) mediated liver-cell proliferation through CyclinD1 regulation

OBJECTIVE

Hepatitis B Virus (HBV) DNA integration and HBV X (HBx) deletion mutation occurs in HBV-positive liver cancer patients, and C-terminal deletion in HBx gene mutants are highly associated with hepatocarcinogenesis. Our previous study found that the HBx-d382 deletion mutant (deleted at nt 382-400) can down-regulate miR-338-3p expression in HBx-expressing cells. The aim of the present study is to examine the role of miR-338-3p in the HBx-d382-mediated liver-cell proliferation.

METHODS

We established HBx-expressing LO2 cells by Lipofectamine 2000 transfection. A miR-338-3p mimics or inhibitor was transfected into LO2/HBx-d382 and LO2/HBx cells using miR-NC as a control miRNA. In silico analysis of potential miR-338-3p targets revealed that miR-338-3p could target the cell cycle regulatory protein CyclinD1. To confirm that CyclinD1 is negatively regulated by miR-338-3p, we constructed luciferase reporters with wild-type and mutated CyclinD1-3'UTR target sites for miR-338-3p binding. We examined the CyclinD1 expression by real-time PCR and western blot, and proliferation activity by flow cytometric cell cycle analysis, Edu incorporation, and soft agar colony.

RESULTS

HBx-d382 exhibited enhanced proliferation and CyclinD1 expression in LO2 cells. miR-338-3p expression inhibited cell proliferation in LO2/HBx-d382 cells (and LO2/HBx cells), and also negatively regulated CyclinD1 protein expression. Of the two putative miR-338-3p binding sites in the CyclinD1-3'UTR region, the effect of miR-338-3p on the second binding site (nt 2397-2403) was required for the inhibition.

CONCLUSION

miR-338-3p can directly regulate CyclinD1 expression through binding to the CyclinD1-3'UTR region, mainly at nt 2397-2403. Down-regulation of miR-338-3p expression is required for liver cell proliferation in both LO2/HBx and LO2/HBx-d382 mutant cells, although the effect is more pronounced in LO2/HBx-d382 cells. Our study elucidated a novel mechanism, from a new miRNA-regulation perspective, underlying the propensity of HBx deletion mutants to induce hepatocarcinogenesis at a faster rate than HBx.

Chaperoning of mutant p53 protein by wild-type p53 protein causes hypoxic tumor regression

Mutant (Mt) p53 abrogates tumor suppression functions of wild-type (WT) p53 through mutant-specific, gain-of-function effects, and patients bearing Mt p53 are chemoresistant. The dominant negative effect of p53 mutants results from their aggregation propensity which causes co-aggregation of WT p53. We explored the mechanism of p53 inactivation in hypoxia and hypothesized whether WT p53 could rescue Mt p53 in hypoxic tumors. WT p53 exists in mutant conformation in hypoxic core of MCF-7 solid tumors, and its conformation is oxygen-dependent. Under simulated hypoxia in cells, WT p53 undergoes conformational change in acquiring mutant conformation. An in vivo chaperone assay shows that WT p53 functions as a molecular chaperone in rescuing conformational and structural p53 mutants in cancer cells both at the transcription and proteome levels. WT p53 chaperone therapy is further shown to cause significant regression of tumor xenografts through reconversion of the mutant phenotype to wild-type p53. The chaperone function of WT p53 is directly linked to the induction of apoptosis in both cancer cells and tumor xenografts. As oncogenic p53 mutants are linked to chemoresistance in hypoxic tumors, p53 chaperone therapy will introduce new dimensions to existing cancer therapeutics. We propose that in cancer cells, WT p53 chaperoning may either exist as a cellular event to potentially reverse the dominant negative effect of its oncogenic mutants or to stabilize yet unidentified factors.

Expression of c-Kit, p-ERK and cyclin D1 in malignant melanoma: an immunohistochemical study and analysis of prognostic value

BACKGROUND

The mitogen-activated protein kinase (MAPK) signaling pathway is one of the major cascades that are crucial for the initiation and progression of melanoma; however, the influence of these signaling molecules on patient survival has not been clarified.

OBJECTIVE

The purpose of this study was to analyze the protein expression of MAPK signaling molecules in melanoma, and to correlate the expression status with clinicopathologic parameters.

METHODS

Expression of c-Kit, phosphorylated ERK (p-ERK), and cyclin D1 was examined by immunohistochemistry in 78 primary melanomas, 24 metastatic lesions, and in 42 benign nevi. The following clinicopathologic variables were evaluated: age, gender, histologic type, tumor site, Breslow thickness, Clark's level, ulceration, and survival period. Statistical analyses were performed for assessment of associations and melanoma-specific survival.

RESULTS

The expression of c-Kit, p-ERK, and cyclin D1 was significantly higher in primary melanomas than in nevi. c-Kit immunoreactivity was highest in thin (Tis-pT2) melanomas, and showed a significant reduction with tumor progression and metastasis. The expression of p-ERK was high in all stages of melanoma. Cyclin D1 positivity increased significantly according to tumor progression, but decreased in metastases. A significant correlation between p-ERK and cyclin D1 expression was observed. Survival analysis failed to detect any trends towards shorter or longer survival among patients expressing either c-Kit, p-ERK or cyclin D1.

CONCLUSIONS

The expression of c-Kit, p-ERK, and cyclin D1 might help to differentiate thin melanoma from melanocytic nevus, but it appears to lack prognostic potential.

Specific targeting of Wnt/β-catenin signaling in human melanoma cells by a dietary triterpene lupeol

Wingless (Wnt) signaling pathway regulates a variety of cellular processes including proliferation, differentiation, survival, apoptosis and cell motility. Aberrant activation of Wnt/β-catenin pathway has been observed in approximately one-third of melanomas and this subset has very poor prognosis suggesting that targeting Wnt signaling could be a promising strategy against this subtype. Mel 928 and Mel 1241 melanoma cells representative of cells with constitutive activation of Wnt/β-catenin signaling pathway and Mel 1011 representative of cells that lack this pathway were treated with a dietary triterpene lupeol and its effects on growth, proliferation, β-catenin transcriptional activity and Wnt target genes were determined both in vitro and in vivo. Lupeol treatment to Mel 928 and Mel 1241 but not Mel 1011 cells resulted in a dose-dependent (i) decrease in cell viability, (ii) induction of apoptosis, (iii) decrease in colonogenic potential, (iv) decrease in β-catenin transcriptional activity and (v) decrease in the expression of Wnt target genes. Most importantly, lupeol restricted the translocation of β-catenin from the cytoplasm to the nucleus. Lupeol also decreased the growth of Mel 928 but not Mel 1011-derived tumors implanted in the athymic nude mice. The decrease in Mel 928-derived tumor growth was associated with a decrease in the expression of Wnt target genes c-myc, cyclin D1, proliferation markers proliferating cell nuclear antigen and Ki-67 and invasion marker osteopontin. We suggest that lupeol alone or as an adjuvant to current therapies could be developed as an agent for the management of human melanomas harboring constitutive Wnt/β-catenin signaling.

Transfection of the wild-type xeroderma pigmentosum group D gene alters the biological behavior of human cholangiocarcinoma cell line QBC939

AIM: To investigate the impact of tranfection of the wild-type xeroderma pigmentosum group D (XPD) gene on the biological behavior of human cholangiocarcinoma cell line QBC939.

METHODS: Empty plasmid pEGFP-N2 and recombinant plasmid pECFP-N2-XPD were digested with KPN I, BGI II and SPH I for plasmid identification. Cells were divided into four groups: pEGFP-N2-XPD group, pEGFP-N2 group, Lipofectamine (Lip) group, and blank control group. Cells were transfected with Lipofectamine. The expression of green fluorescent protein (GFP) was observed under a fluorescence microscope. The mRNA expression of wild-type XPD, p53, cyclin D1 and c-myc was detected by reverse transcription-polymerase chain reaction (RT-PCR). Flow cytometry (FCM) was employed for examining the cell cycle of transfected QBC939 cells. Cell proliferation was detected by methyl thiazolyl tetrazolium (MTT) assay.

RESULTS: The relative expression level of XPD mRNA in the pEGFP-N2-XPD group was significantly higher than those in the pEGFP-N2 group, Lip group and blank control group (0.778 ± 0.018 vs 0.561 ± 0.039, 0.544 ± 0.035 and 0.542 ± 0.034, respectively; all P < 0.01). The relative expression level of p53 mRNA in the pEGFP-N2-XPD group was also significantly higher than those in the pEGFP-N2 group, Lip group and blank control group (0.421 ± 0.019 vs 0.256 ± 0.014, 0.267 ± 0.015 and 0.274 ± 0.018, respectively; all P < 0.01). The relative expression level of cyclin D1 mRNA in the pEGFP-N2-XPD group was significantly lower than those in the pEGFP-N2 group, Lip group and blank control group (0.339 ± 0.041 vs 0.560 ± 0.039, 0.558 ± 0.050 and 0.560 ± 0.041, respectively; all P < 0.01). The relative expression level of c-myc mRNA in the pEGFP-N2-XPD group was also significantly lower than those in the pEGFP-N2 group, Lip group and blank control group (0.355 ± 0.045 vs 0.570 ± 0.075, 0.560 ± 0.041 and 0.537 ± 0.050, respectively; all P < 0.01). FCM results showed that the percentage of cells in G₁ phase was significantly higher (81.65% vs 65.54%, 56.61% and 63.26%, respectively; all P < 0.05) and that in S1 phase was significantly lower (11.83% vs 24.10%, 29.52% and 27.28%; all P < 0.05) in the pEGFP-N2-XPD group than in the pEGFP-N2 group, Lip group and blank control group. MTT assay revealed that the growth rate of cells in the pEGFP-N2-XPD group was significantly lower than those in the other three groups (all P < 0.01).

CONCLUSION: Transfection of the wild-type XPD gene can inhibit the proliferation of human QBC939 cells in vitro, down-regulate the expression of cyclin D1 and c-myc mRNAs, and up-regulate the expression of p53 mRNA.

Cyclin D2 protein stability is regulated in pancreatic beta-cells

The molecular determinants of beta-cell mass expansion remain poorly understood. Cyclin D2 is the major D-type cyclin expressed in beta-cells, essential for adult beta-cell growth. We hypothesized that cyclin D2 could be actively regulated in beta-cells, which could allow mitogenic stimuli to influence beta-cell expansion. Cyclin D2 protein was sharply increased after partial pancreatectomy, but cyclin D2 mRNA was unchanged, suggesting posttranscriptional regulatory mechanisms influence cyclin D2 expression in beta-cells. Consistent with this hypothesis, cyclin D2 protein stability is powerfully regulated in fibroblasts. Threonine 280 of cyclin D2 is phosphorylated, and this residue critically limits D2 stability. We derived transgenic (tg) mice with threonine 280 of cyclin D2 mutated to alanine (T280A) or wild-type cyclin D2 under the control of the insulin promoter. Cyclin D2 T280A protein was expressed at much higher levels than wild-type cyclin D2 protein in beta-cells, despite equivalent expression of tg mRNAs. Cyclin D2 T280A tg mice exhibited a constitutively nuclear cyclin D2 localization in beta-cells, and increased cyclin D2 stability in islets. Interestingly, threonine 280-mutant cyclin D2 tg mice had greatly reduced beta-cell apoptosis, with suppressed expression of proapoptotic genes. Suppressed beta-cell apoptosis in threonine 280-mutant cyclin D2 tg mice resulted in greatly increased beta-cell area in aged mice. Taken together, these data indicate that cyclin D2 is regulated by protein stability in pancreatic beta-cells, that signals that act upon threonine 280 limit cyclin D2 stability in beta-cells, and that threonine 280-mutant cyclin D2 overexpression prolongs beta-cell survival and augments beta-cell mass expansion.

Gentherapie

Die Gentherapie ist eine junge Wissenschaft, die Nukleinsäuren zur Therapie einsetzt (Hengge u. Bardenheuer 2004). Die somatische Gentherapie befasst sich mit der Behandlung von somatischen (Körper-)Zellen (⧁ Tab. 4.1.1), wobei das therapeutische Gen ein im Organismus benötigtes Protein kodiert.

Downregulation of cell cycle modulators p21, p27, p53, Rb and proapoptotic Bcl-2-related proteins Bax and Bak in cutaneous melanoma is associated with worse patient prognosis: preliminary findings

BACKGROUND

Cutaneous melanoma is a tumor with high metastatic potential, but the mechanisms leading to progression are still not fully understood. To provide further molecular basis for understanding the progression of melanoma, the aim of this study was to examine the expression pattern of cell cycle modulators (p21, p27, p53 and Rb) and proapoptotic multidomain Bcl-2 related proteins (Bax and Bak) and to analyze its differences in patients with and without progression stages.

METHODS

We have studied 31 patients with cutaneous melanoma at stage IIa (Breslow thickness 1.5-4.0 mm), and follow them for 10-year period. Eighteen of these patients developed metastasis. The determination of selected molecular markers participating in cell cycle regulation and apoptosis was performed by immunohistochemistry.

RESULTS

We have observed a significant increase in the loss of expression of the Bax, Bak, p21, p27, p53 and Rb. The analysis of the relationship between these downregulated markers and Breslow thickness showed significant positive correlation (r=0.556, p=0.029) and predictive value if thickness below 2.3 mm (OR=3.0, 95% CI=0.312-28.84).

CONCLUSIONS

Our study showed that the downregulation of the markers associated with cell cycle control and apoptosis is of great value in predicting malignant transformation and in assessing the risk of metastases development for 10-year follow-up period.

Transcriptional profiles in melanocytes from clinically unaffected skin distinguish the neoplastic growth pattern in patients with melanoma

BACKGROUND

It is generally accepted that sunlight may contribute to the development of melanoma.

OBJECTIVES

To analyse gene expression of melanocytes obtained from clinically unaffected skin of patients with melanoma and healthy controls before and after exposure to ultraviolet B radiation.

METHODS

Using GeneChip array technology, the gene expression of melanocytes obtained from the two donor groups was profiled, in order to identify transcriptional differences affecting susceptibility to melanoma.

RESULTS

The data collected did not show any difference between the expression profiles of melanocytes purified from normal donors and from patients with melanoma that was able to give a statistically significant class separation. However, by means of unsupervised clustering our data could be divided into two main classes. The first class included the transcriptome profiles of melanocytes obtained from skin samples of patients with a vertical growth phase (VGP) melanoma, while the second class included the transcriptome profiles of melanocytes obtained from skin samples of patients with a radial growth phase (RGP) melanoma.

CONCLUSIONS

These data suggest that melanocytes in patients with VGP and RGP melanomas show significant differences in gene expression profiles, which allow us to classify patients with melanoma also from clinically unaffected skin.

Sodium arsenite accelerates TRAIL-mediated apoptosis in melanoma cells through upregulation of TRAIL-R1/R2 surface levels and downregulation of cFLIP expression

AP-1/cJun, NF-kappaB and STAT3 transcription factors control expression of numerous genes, which regulate critical cell functions including proliferation, survival and apoptosis. Sodium arsenite is known to suppress both the IKK-NF-kappaB and JAK2-STAT3 signaling pathways and to activate the MAPK/JNK-cJun pathways, thereby committing some cancers to undergo apoptosis. Indeed, sodium arsenite is an effective drug for the treatment of acute promyelocytic leukemia with little nonspecific toxicity. Malignant melanoma is highly refractory to conventional radio- and chemotherapy. In the present study, we observed strong effects of sodium arsenite treatment on upregulation of TRAIL-mediated apoptosis in human and mouse melanomas. Arsenite treatment upregulated surface levels of death receptors, TRAIL-R1 and TRAIL-R2, through increased translocation of these proteins from cytoplasm to the cell surface. Furthermore, activation of cJun and suppression of NF-kappaB by sodium arsenite resulted in upregulation of the endogenous TRAIL and downregulation of the cFLIP gene expression (which encodes one of the main anti-apoptotic proteins in melanomas) followed by cFLIP protein degradation and, finally, by acceleration of TRAIL-induced apoptosis. Direct suppression of cFLIP expression by cFLIP RNAi also accelerated TRAIL-induced apoptosis in these melanomas, while COX-2 suppression substantially increased levels of both TRAIL-induced and arsenite-induced apoptosis. In contrast, overexpression of permanently active AKTmyr inhibited TRAIL-mediated apoptosis via downregulation of TRAIL-R1 levels. Finally, AKT overactivation increased melanoma survival in cell culture and dramatically accelerated growth of melanoma transplant in vivo, highlighting a role of AKT suppression for effective anticancer treatment.

Adenovirus-mediated TA-p73β gene transfer increases chemosensitivity of human malignant melanomas

Malignant melanoma is the most aggressive form of skin cancer and has proven to be highly resistant to conventional chemotherapy. Intriguingly, the p53 tumor suppressor, a main mediator of chemoresistance in other tumor types, is rarely mutated in melanoma. However, we have previously shown that anti-apoptotic isoforms of p73 (deltaTA-p73), another member of the p53 family, are overexpressed in metastatic melanomas. DeltaTA-p73 can oppose the pro-apoptotic functions of p53 and full length p73, and thus it could contribute to melanoma chemoresistance. In this study, we use an efficient adenoviral-based gene transfer approach to introduce a transcriptionally active form of p73 (TA-p73beta) in melanoma cells, with the objective of overcoming drug resistance. Interestingly, TA-p73beta significantly sensitized 5 out of 7 aggressive melanoma cell lines to the standard therapeutic agents adriamycin and cisplatin. More importantly, TA-p73beta displayed a synergistic effect in vivo allowing adriamycin or cisplatin to block melanoma cell growth in mouse xenograft models (p < 0.05). In summary, our data show that Ad-mediated TA-p73beta gene expression can markedly sensitize a subset of melanoma cell lines to adriamycin and cisplatin in vitro and in vivo, suggesting a new chemosensitization strategy for malignant melanomas.

Recombinant polymers for cancer gene therapy: A minireview

A major challenge for successful cancer gene therapy is the development of safe and effective gene delivery vectors. Gene delivery vectors can be viral or nonviral. Among nonviral vectors various polymeric vectors have shown potential in gene delivery. However, much work needs to be done in order to correlate polymer structure with gene release at the target site and transfection efficiency. This article is a brief introduction into cancer gene therapy, barriers and methods for gene transfer with emphasis on the applications of recombinant polymers for cancer gene therapy.

Current strategies in cancer gene therapy

Cancer gene therapy is the most studied application of gene therapy. Many genetic alterations are involved in the transformation of a normal cell into a neoplastic one. The two main gene groups involved in cancer development are oncogenes and tumor suppressor genes. While the latter eliminates cancerous cells via apoptosis, the former enhances cell proliferation. Therefore, apoptotic genes and anti-oncogenes are widely used in cancer gene therapy. In addition to oncogenes and tumor suppressor genes, chemotherapy and gene therapy can be combined through suicide gene strategy. A suicide gene encodes for a non-mammalian enzyme; this enzyme is used to convert a non-toxic prodrug into its active cytotoxic metabolite within the cancerous cells. Tumor suppressor genes, anti-oncogenes and suicide genes target cancer cells on the molecular level. On the other hand, cancer is immunogenic in nature; therefore, it can also be targeted on the immunological level. Boosting the immune response against cancerous cells is usually achieved via genes encoding for cytokines. Interleukin-12 gene, for example, is one of the most studied cytokine genes for cancer gene therapy applications. DNA vaccines are also used after conventional treatments to eliminate remnant malignant cells. All these therapeutic strategies and other strategies namely anti-angiogenesis and drug resistant genes are briefly reviewed and highlighted in this article.

New advances on the functions of epidermal growth factor receptor and ceramides in skin cell differentiation, disorders and cancers

Recent advances in understanding of the biological functions of the epidermal growth factor and epidermal growth factor receptor (EGF-EGFR) system and ceramide production for the maintenance of skin integrity and barrier function are reported. In particular, the opposite roles of EGFR and ceramide cascades in epithelial keratinocyte proliferation, migration and terminal differentiation are described. Moreover, the functions of ceramides in the epidermal permeability barrier are reviewed. The alterations in EGFR signaling and ceramide metabolism, which might be involved in the etiopathogenesis of diverse skin disorders and cancers, are described. New progress in understanding of skin organization, which might provide the basis for the design of new transcutaneous drug delivery techniques as well as for the development of new therapies of skin disorders and cancers, are reported.

A novel antisense inhibitor of MMP-9 attenuates angiogenesis, human prostate cancer cell invasion and tumorigenicity

Androgen deprivation therapy causes a paradoxical elevation of matrix metalloproteinases (MMPs) including MMP-9 resulting in aggressive tumor phenotype in many patients with prostate cancer. In this study, we have evaluated a novel antisense phosphorodiamidate Morpholino oligomer (PMO) targeted against MMP-9 in models of angiogenesis and in human prostate xenograft in athymic mice. The treatment of androgen-independent DU145 human prostate cells with a 21-mer MMP-9 antisense PMO caused a dose-dependent inhibition of cell proliferation compared to scrambled or MMP-2 antisense PMO at similar concentrations. This was associated with decreases in MMP-9 expression, gelatinolytic activity and increased stability of the insulin-like growth factor-binding protein (IGFBP-3), a proapoptotic factor and MMP-9 substrate. In vitro invasion assays revealed a 40-60% inhibition of DU145 cell invasion in the presence of 25 microM MMP-9 antisense PMO. A significant decrease in endothelial cell migration and vascularization was observed in the Matrigel plug assay in mice when treated intraperitoneally with 300 microg/day MMP-9 antisense for 21 days. In the highly vascular DU145 tumor xenografts, MMP-9 inhibition caused decreased tumor growth with regression in 50% of the animals. Histological analysis revealed increased apoptosis and fibrous tissue deposits in the MMP-9 antisense-treated tumors compared to the scrambled and saline controls. No apparent toxicity or mortality was associated with the MMP-9 PMO treatment. In summary, the MMP-9 antisense PMO inhibited in vitro prostate cancer cell proliferation, invasion and in vivo angiogenesis. These data establish the feasibility of developing a site-directed, nontoxic antisense therapeutic agent for inhibiting local invasion and metastasis.

Cyclin D1 is essential for neoplastic transformation induced by both E6/E7 and E6/E7/ErbB-2 cooperation in normal cells

More than 25% of head and neck squamous cell carcinomas (HNSCC) and 99% of cervical cancers (CxCa) are positive for high-risk human papillomaviruses (HPVs). Furthermore, the type I tyrosine kinase receptor ErbB-2 is overexpressed in at least 30% of HNSCC and CxCa. Recently, we demonstrated that E6/E7 of HPV type 16 cooperate with ErbB-2 to induce cell transformation of human normal oral epithelial (NOE) cells. This is accompanied by overexpression of cyclin D1 in NOE cells. To determine the role of cyclin D1 in E6/E7/ErbB-2 cooperation, we examined the independent effects of E6/E7 and ErbB-2, and the combined effect of E6/E7 and ErbB-2 in mouse normal embryonic fibroblast (NEF), wild type (wt), and knockout cyclin D1 (D1(-/-)) cells. We report that NEF-wt cells transduced with E6/E7 alone and E6/E7/ErbB-2 together form small and large tumors in nude mice, respectively, as well as different sized colonies in soft agar; whereas ErbB-2 alone elicits neither tumor formation in vivo nor colony formation in soft agar. More importantly, E6/E7, ErbB-2 and E6/E7/ErbB-2 together all fail to induce neoplastic transformation of cyclin D1(-/-) cells in vivo and in vitro. Furthermore, using antisense cyclin D1 we completely inhibited tumor and colony formation of NEF-wt-E6/E7 and wt-E6/E7-ErbB-2 as well as human NOE-E6/E7-ErbB-2-transformed cells. These analyses reveal that cyclin D1 is the downstream target of the neoplastic transformation induced by E6/E7 or E6/E7/ErbB-2 cooperation in normal cells. Our data suggest that anti-cyclin D1 therapy may be highly specific in the treatment of all human cancers expressing high-risk HPVs or HPVs/ErbB-2.

Pharmacology of cytotoxic agents: a helpful tool for building dose adjustment guidelines in the elderly

Aging is associated with multidimensional changes, including alterations in physiological functions, co-morbidities and poly-medications. These changes may lead to modifications in the absorption, distribution, metabolism and excretion of drugs. The lack of a scientific basis for optimal drug dosing in the elderly is a major problem. The development and validation of guidelines are therefore essential to improve treatment administration and monitoring in elderly patients. Even though it has been widely demonstrated that standard therapies used in adults may be of great benefit in the elderly, there may be a higher incidence of toxicity. This could be avoided by using dosage individualization based on a sound knowledge of the physiological factors implicated in the pharmacokinetic (PK) characteristics of the drugs administered and in their observed pharmacodynamic (PD) effects in each patient. The so-called "population modeling" approach renders such studies feasible by allowing the analysis of PK-PD relationships from sparse observational data.

Apoptosis and melanoma chemoresistance

Melanoma is the most aggressive form of skin cancer and is notoriously resistant to all current modalities of cancer therapy. A large set of genetic, functional and biochemical studies suggest that melanoma cells become 'bullet proof' against a variety of chemotherapeutic drugs by exploiting their intrinsic resistance to apoptosis and by reprogramming their proliferation and survival pathways during melanoma progression. In recent years, the identification of molecules involved in the regulation and execution of apoptosis, and their alteration in melanoma, have provided new insights into the molecular basis for melanoma chemoresistance. With this knowledge in hand, the challenge is now to devise strategies potent enough to compensate or bypass these cell death defects and improve the actual poor prognosis of patients at late stages of the disease.