Unique induction of p21(WAF1/CIP1)expression by vinorelbine in androgen-independent prostate cancer cells

To study the mechanisms of the development of hormone refractory prostate cancer, we established an androgen-independent (AI) prostate cancer cell line derived from hormone-dependent (AD) LNCaP cells. Our previous studies have demonstrated that AI cells are deficient in expression of p21(WAFl/CIP1) (p21) due to overexpressed AR and are resistant to apoptosis. In this study, the induction of p53 and p21 expression by vinorelbine (Navelbine) was compared between AD and AI cells in an attempt to understand the difference(s) in apoptotic signalling pathways in these cells. Using a series of deletion of p21 reporter constructs, we found that vinorelbine mediated p21 induction in a p53-dependent manner in AD cells. In contrast, p21 expression restored by vinorelbine in AI cells was found to be through both p53-dependent and-independent pathways. In the absence of two p53 binding sites, Spl-3 and Spl-4 sites, in the promoter of human p21 gene, were found to be required for vinorelbine-mediated p21 activation. No p21 induction was observed by paclitaxel in AI cells. Exposure of AI cells to paciltaxel followed by vinorelbine produced synergism. Our data, thus, provide a basis for the synergistic combination of vinorelbine and paclitaxel for the treatment of advanced prostate cancer.     

Breast cancer: patient information needs reflected in English and German web sites

Individual belief and knowledge about cancer were shown to influence coping and compliance of patients. Supposing that the Internet information both has impact on patients and reflects patients' information needs, breast cancer web sites in English and German language were evaluated to assess the information quality and were compared with each other to identify intercultural differences. Search engines returned 10 616 hits related to breast cancer. Of these, 4590 relevant hits were analysed. In all, 1888 web pages belonged to 132 English-language web sites and 2702 to 65 German-language web sites. Results showed that palliative therapy (4.5 vs 16.7%; P=0.004), alternative medicine (18.2 vs 46.2%; P<0.001), and disease-related information (prognosis, cancer aftercare, self-help groups, and epidemiology) were significantly more often found on German-language web sites. Therapy-related information (including the side effects of therapy and new studies) was significantly more often given by English-language web sites: for example, details about surgery, chemotherapy, radiotherapy, hormone therapy, immune therapy, and stem cell transplantation. In conclusion, our results have implications for patient education by physicians and may help to improve patient support by tailoring information, considering the weak points in information provision by web sites and intercultural differences in patient needs.     

Molecular Mechanism of Differentiation and Apoptosis of U937 Cells Induced by 12-O-Tetradecanoylphorbol-13-Acetate

OBJECTIVE To explore the effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) on differentiation, apoptosis and related molecular mechanisms in U937 myelomonocytic leukemia cells.METHODS Morphological changes were analyzed by phase contrast and light microscopy, expression of the monocytic differentiation maker CD11b by direct immunofluorescence staining, cell cycle distribution and apoptosis by flow cytometry, and expression of bcl-2, Bax, survivin and p21Cip1/Waf1proteins by Western analysis.RESULTS Treatment of U937 cells with 10 nmol/L TPA induced cell adherence. The adherent cells showed G0/G1 cell cycle arrest (69.0% at 24h vs 52.1% control; P< 0.01),and morphologic changes and increased expression of the monocytic differentiation marker CD11b (63.0% at 72 h vs15.3% control; P< 0.01 ). In addition to these effects, about 20% of the cells still remained in suspension and exhibited a time-dependent increasing apoptosis, which reached 70.3% after 72 h of treatment ( P< 0.01 ). TPA treatment for 24 h induced expression of p21Cip1/Waf1 in the adherent cells, but not in the non-adherent cells. Furthermore, bcl-2 and survivin expression declined in 24 h-TPA-treated non-adherent cells compared with untreated control and adherent cells, whereas no change in the expression of Bax was detected.CONCLUSION TPA induces both differentiation and apoptosis in U937 cells,which may be related to the upregulation of p21Cip1/Waf1 and downregulation of bcl-2 and survivin expression.     

Hydrogen ion dynamics and the Na+/H+ exchanger in cancer angiogenesis and antiangiogenesis

Tumour angiogenesis and cellular pH regulation, mainly represented by Na(+)/H(+) antiporter exchange, have been heretofore considered unrelated subfields of cancer research. In this short review, the available experimental evidence relating these areas of modern cancer research is introduced. This perspective also helps to design a new approach that facilitates the opening and development of novel research lines oriented towards a rational incorporation of anticancer drugs into more selective and less toxic therapeutic protocols. The final aim of these efforts is to control cancer progression and dissemination through the control of tumour angiogenesis. Finally, different antiangiogenic drugs that can already be clinically used to this effect are briefly presented.     

p21(Waf1/Cip1) and p53 are downstream effectors of protein kinase C delta in tumor suppression and differentiation in human colon cancer cells

We have previously demonstrated that the delta isoform of protein kinase C (PKCdelta) is importantly involved in cell growth inhibition and tumor suppression in colon cancer cells. To investigate further the activity and mechanism of action of PKCdelta, we have retrovirally transduced a PKCdelta cDNA in HCT116 human colon cancer cells. PKCdelta-overexpressing cells (HCT116/PKCdelta) were growth-inhibited, showed marked morphologic changes and underwent multinucleation and phenotypic changes characteristic of mitotic catastrophe. Compared to controls, HCT116/PKCdelta cells showed a highly attenuated tumorigenic profile and poor anchorage-independent growth. In addition, transfected cells established junction-coordinated intercellular communications, expressed cell surface microvilli and overexpressed the colon differentiation marker alkaline phosphatase. HCT116/PKCdelta cells also produced the 89 kDa, carboxy-terminal catalytic domain of PARP. In HCT116/PKCdelta cells, p21(Waf1/Cip1) and p53 were transiently upregulated for 48 hr after PKCdelta transduction. In a p21 null subline of HCT116 cells (HCT116/p21null), overexpression of PKCdelta did not affect tumorigenicity or differentiation, indicating that p21 is essential for the antitumorigenic activity of PKCdelta. Similarly, overexpression of PKCdelta caused no significant phenotypic changes in HCT116/E6 cells, an HCT116 subline in which the p53 protein is downregulated by the human papillomavirus E6 gene product. We conclude that overexpression of PKCdelta in human colon cancer cells induces multiple antineoplastic effects that depend on the activities of p21(Waf1/Cip1) and p53.     

Inhibition of cell growth and induction of G1-phase cell cycle arrest in hepatoma cells by steroid extract from Meretrix meretrix

In this study, we report that the steroid extract 5alpha, 8alpha-epidioxycholest-6-ene-3beta-ol (MME) from Meretrix meretrix has the ability to inhibit growth of hepatoma cells and to induce G1-phase cell cycle arrest in two human hepatoma cell lines, HepG2 and Hep3B. HepG2 cells were more sensitive than Hep3B to MME. The extract markedly up-regulated the expression of p53 and p21WAF1/CIP1 in HepG2, suggesting that MME-induced G1 phase cell cycle arrest in HepG2 might be p53-dependent. Therefore, the up-regulation of p27KIP1and p16INK4A in both cell lines indicates that a p53-independent pathway might be involved in the mechanism of MME inducing cell cycle arrest. In conclusion, MME induces G1 phase cell cycle arrest via both p53-dependent and p53-independent pathways.     

Amplified centrosomes in breast cancer: a potential indicator of tumor aggressiveness

Molecular mechanisms leading to genomic instability and phenotypic variation during tumor development and progression are poorly understood. Such instability represents a major problem in the management of breast cancer because of its contribution to more aggressive phenotypes as well as chemoresistance. In this study we analyzed breast carcinomas and tumor-derived cell lines to determine the relationship between centrosome amplification and established prognostic factors. Our results show that centrosome amplification can arise independent of ER or p53 status and is a common feature of aneuploid breast tumors. Centrosome amplification is associated with mitotic spindle abnormalities in breast carcinomas and thus may contribute to genomic instability and the development of more aggressive phenotypes during tumor progression.     

HDAC3 overexpression and colon cancer cell proliferation and differentiation

An immunohistochemical analysis of human colorectal adenocarcinomas showed that cancer cells express widely varying levels of HDAC3. The SW480 colon cancer cell line was found to express high levels of HDAC3 compared to other colon cancer cell lines. p21 was poorly induced in SW480 cells relative to the lower HDAC3-expressing HT-29 cells. RNAi-induced reduction of HDAC3 in SW480 cells increased their constitutive, butyrate-, TSA-, and TNF-alpha-induced expression of p21, but did not cause all the gene expression changes induced upon general histone deacetylase (HDAC) inhibition. SW480 cells with lower HDAC3 expression appeared to be poised for gene expression responses with increased histone H4-K12 acetylation, but not K5, K8, or K16 acetylation. Even though p21 was readily activated in HT29 cells, HDAC3 siRNA nonetheless stimulated p21 expression in these cells to a greater degree than HDAC1 and HDAC2 siRNA. SW480 cells with lower HDAC3 levels displayed an enhanced cell cycle arrest and growth inhibition by butyrate, but without changes in apoptosis or sensitivity to chemotherapeutic agents. As reported for other colon cancer cell lines, butyrate induced the rapid downregulation of the secretory cell differentiation markers mucin 2 and intestinal trefoil factor in SW480 cells. Interestingly, selective HDAC3 inhibition was sufficient to downregulate these genes. Our data support a central role for HDAC3 in regulating the cell proliferation and differentiation of colon cancer cells and suggest a potential mechanism by which colon cancers may become resistant to luminal butyrate.     

Phellinus linteus sensitises apoptosis induced by doxorubicin in prostate cancer

It has been demonstrated that the Phellinus linteus (PL) mushroom, which mainly consists of polysaccharides, possesses antitumour activity. The mechanisms of PL against malignant growth remain unknown. The anticancer drug doxorubicin (Dox) has been shown to induce apoptosis via initiating a caspase cascade. In this investigation, we tested the effect of PL on Dox-induced apoptosis in prostate cancer LNCaP cells. We showed that PL or Dox, at relatively low doses, does not induce apoptosis in the cells. However, combination treatment with low doses of PL and Dox results in a synergistic effect on the induction of apoptosis. In this apoptotic process, caspases 8, 3 and BID are cleaved, and the addition of caspase inhibitor z-VADfmk completely blocks apoptosis. In addition, JNK is activated in response to PL or the combination treatment in LNCaP cells. The suppression of JNK partially inhibits the induction of apoptosis elicited by the co-treatment. These findings indicate that PL has a synergistic effect with Dox to activate caspases in prostate cancer LNCaP cells. Our study also suggests that PL has therapeutic potential to augment the magnitude of apoptosis induced by antiprostate cancer drugs.     

JNK interacting protein 1 (JIP-1) protects LNCaP prostate cancer cells from growth arrest and apoptosis mediated by 12-0-tetradecanoylphorbol-13-acetate (TPA)

12-0-tetradecanoylphorbol-13-acetate (TPA) stimulates protein kinase C (PKC) which mediates apoptosis in androgen-sensitive LNCaP human prostate cancer cells. The downstream signals of PKC that mediate TPA-induced apoptosis in LNCaP cells are unclear. In this study, we found that TPA activates the c-Jun NH2-terminal kinase (JNK)/c-Jun/AP-1 pathway. To explore the possible role that the JNK/c-Jun/AP-1 signal pathway has on TPA-induced apoptosis in LNCaP cells, we stably transfected the scaffold protein, JNK interacting protein 1 (JIP-1), which binds to JNK inhibiting its ability to phosphorylate c-Jun. TPA (10(-9)-10(-7) mol l(-1)) caused phosphorylation of JNK in both wild-type and JIP-1-transfected (LNCaP-JIP-1) cells. It resulted in phosphorylation and upregulation of expression of c-Jun protein in the wild-type LNCaP cells, but not in the JIP-1-transfected LNCaP cells. In addition, upregulation of AP-1 reporter activity by TPA (10(-9) mol l(-1)) occurred in LNCaP cells but was abrogated in LNCaP-JIP-1 cells. Thus, TPA stimulated c-Jun through JNK, and JIP-1 effectively blocked JNK. TPA (10(-12)-10(-8) mol l(-1)) treatment of LNCaP cells caused their growth inhibition, cell cycle arrest, upregulation of p53 and p21waf1, and induction of apoptosis. All of these effects were significantly attenuated when LNCaP-JIP-1 cells were similarly treated with TPA. A previous study showed that c-Jun/AP-1 blocked androgen receptor (AR) signaling by inhibiting AR binding to AR response elements (AREs) of target genes including prostate-specific antigen (PSA). Therefore, we hypothesised that TPA would not be able to disrupt the AR signal pathway in LNCaP-JIP-1 cells. Contrary to expectation, TPA (10(-9)-10(-8) mol l(-1)) inhibited DHT-induced AREs reporter activity and decreased levels of PSA in the LNCaP-JIP-1 cells. Taken together, TPA, probably by stimulation of PKC, phosphorylates JNK, which phosphorylates and increases expression of c-Jun leading to AP-1 activity. Growth control of prostate cancer cells can be mediated through the JNK/c-Jun pathway, but androgen responsiveness of these cells can be independent of this pathway, suggesting that androgen independence in progressive prostate cancer may not occur through activation of this pathway.     

Alpha-tocopheryl succinate sensitises a T lymphoma cell line to TRAIL-induced apoptosis by suppressing NF-kappaB activation

Activation of nuclear factor-kappaB (NF-kappaB) can interfere with induction of apoptosis triggered by the tumour necrosis factor-related apoptosis-inducing ligand (TRAIL; Apo2L). Therefore, agents that suppress NF-kappaB activation may sensitise cells to TRAIL-dependent apoptosis. Exposure of Jurkat cells to TRAIL resulted in massive and saturable apoptosis induction, following an initial lag time. This lag was abolished by pretreatment of the cells with subapoptotic doses of alpha-tocopheryl succinate (alpha-TOS) or the proteasome inhibitor MG132. Exposure of the cells to TRAIL led to a rapid, transient activation of NF-kappaB, a process that was suppressed by cell pretreatment with alpha-TOS or MG132. Activation of NF-kappaB by TNF-alpha prior to TRAIL exposure increased resistance of the cells to TRAIL-mediated apoptosis. We conclude that alpha-TOS sensitises cells to TRAIL killing, at least in some cases, through inhibition of NF-kappaB activation. This further supports the possibility that this semisynthetic analogue of vitamin E is a potential adjuvant in cancer treatment, such as in the case of TRAIL-mediated inhibition of cancer.     

Cellular response and activation of apoptosis by mithramycin SK in p21-deficient HCT116 human colon carcinoma cells

HCT116 (p21^−/−) human colon carcinoma cells treated with mithramycin SK (MSK), a novel analog of the antitumor antibiotic mithramycin A (MTA), were transiently arrested in G2/M, with some cells entering a faulty mitotic cycle without cytokinesis that resulted in G1-like cell arrest, which consisted of post-mitotic aneuploid G1 cells. Some of these cells synthesized DNA and elicited an apoptotic response. The absence of p21^WAF1 made HCT116 cells more sensitive to MSK than to the related MTA. MSK also showed higher antiproliferative activity than MTA on HCT116 cells with different genetic backgrounds, including those lacking the p53 gene. Apoptosis in MSK-treated p21^−/− cells involved caspase 2 rather than caspase 3. Untreated HCT116 (p21^−/−) cells presented a little caspase 3 activity, which increased slightly after treatment with MSK. The apoptotic response in p21^−/− cells comprised caspase 2 acting as an executor caspase together with a loss of mitochondrial membrane potential that may be initiated by caspase 2. In contrast, caspase 3 was activated in wild-type HCT116 after treatment with MSK.     

Perillyl Alcohol Inhibits Human Breast Cancer Cell Growth in vitro and in vivo

The effect of monoterpene perillyl alcohol (POH) on cell growth, cell cycle progression, and expression of cell cycle-regulatory proteins in estrogen receptor (ER)-positive (KPL-1 and MCF-7) and ER-negative (MKL-F and MDA-MB-231) human breast cancer cell lines was examined. POH inhibited cell proliferation in a dose-dependent manner in all cell lines tested. POH at a dose of 500 micro M had a cytostatic effect, in which growth inhibition was due to accumulation of cells in G1-phase. Cell cycle progression was preceded by a decrease in G1 cyclins (cyclin D1 and E), followed by an increase in p21(Cip1/Waf1) and a decrease in proliferating cell nuclear antigen level. Levels of p53 and cyclin A were unchanged. POH at a dose of 75 mg/kg administered intraperitoneally three times a week throughout the entire 6-week experimental period suppressed orthotopically transplanted KPL-1 tumor cell growth and regional lymph node metastasis in a nude mouse system. POH inhibited both ER-positive and -negative human breast cancer cell growth in vitro, and suppressed growth and metastasis in vivo.     

Molecular mechanisms of G0/G1 cell-cycle arrest and apoptosis induced by terfenadine in human cancer cells

Terfenadine (TF), a highly potent histamine H1 receptor antagonist, has been shown to exert no significant central nervous system side effects in clinically effective doses. In this study, we demonstrated that TF induced significant growth inhibition of human cancer cells, including Hep G2, HT 29, and COLO 205 cells, through induction of G(0)/G(1) phase cell-cycle arrest. The minimal dose of TF induced significant G(0)/G(1) arrest in these cells was 1-3 microM. The protein levels of p53, p21/Cip1, and p27/Kip1 were significantly elevated, whereas the kinase activities of cyclin-dependent kinase 2 (CDK2) and CDK4 were inhibited simultaneously in the TF-treated cells. On the other hand, significant apoptosis, but not G(0)/G(1) arrest, was induced in the HL 60 (p53-null) or Hep 3B (with deleted p53) cells when treated with TF (3-5 microM). To clarify the roles of p21/Cip1 and p27/Kip1 protein expression, which was involved in G(0)/G(1) arrest and apoptosis induced by TF in human cancer cells, antisense oligodeoxynucleotides (ODNs) specific to p21/Cip1 and p27/Kip1 were used, and the expression of the p21/Cip1 and p27/Kip1 were monitored by immunoblotting analysis. Our data demonstrated that the percentage of the apoptotic cells detected by annexin V/PI analysis in the TF-treated group was clearly attenuated by pretreatment with p27/Kip1-specific ODNs. These results indicated that p27/Kip1 (but not p21/Cip1) protein indeed played a critical role in the TF-induced apoptosis. We also demonstrated that the TF-induced G(0)/G(1) cell-cycle arrest effect was not reversed by TF removal, and this growth inhibition lasted for at least 7 d. Importantly, the occurrence of apoptosis and cell growth arrest was not observed in the TF-treated normal human fibroblast, even at a dose as high as 25 microM. Our study showed the molecular mechanisms for TF-induced cell growth inhibition and the occurrence of apoptosis in human cancer cells.     

Differential activation of JNK1 isoforms by TRAIL receptors modulate apoptosis of colon cancer cell lines

Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis on binding to its receptors, death receptor 4 and 5 (DR4, DR5). TRAIL can also activate c-Jun N-terminal kinase (JNK) through the adaptor molecules, TNF receptor-associated factor 2 (TRAF2) and receptor-interacting protein (RIP). The role of JNK in TRAIL-induced tumour cell apoptosis is unclear. In this study, we demonstrate that JNK is activated by TRAIL in colon cancer cells. Inhibition of JNK with L-JNKI reduced rhTRAIL-induced cell death but enhanced cell death induced by selective activation of DR4 or DR5. This difference was unrelated to receptor internalisation or differential activation of c-Jun, but activation of different JNK isoforms. Our data demonstrate that JNK1, but not JNK2 is activated by rhTRAIL in the examined colon cancer cell lines. Although rhTRAIL activated both the long and short isoforms of JNK1, selective activation of DR4 or DR5 led to predominant activation of the short JNK1 isoforms (JNK1α1 and/or JNK1β1). Knockdown of JNK1α1 by shRNA enhanced apoptosis induced by TRAIL, agonistic DR4 or DR5 antibodies. On the other hand, knockdown of the long JNK1 isoforms (JNK1α2 and JNK1β2) had the opposite effect; it reduced TRAIL-induced cell death. These data indicate that the short JNK1 isoforms transmit an antiapoptotic signal, whereas the long isoforms (JNK1α2 or JNK1β2) act in a proapoptotic manner.     

MiR-224 promotes the chemoresistance of human lung adenocarcinoma cells to cisplatin via regulating G1/S transition and apoptosis by targeting p21WAF1/CIP1

Background:

Increasing evidence has shown that microRNAs (miRNAs) can serve as oncogenes and tumour suppressors to participate in tumour development. However, the roles of miRNAs in chemoresistance of human lung adenocarcinoma (LA) remain largely undefined.

Methods:

On the basis of miRNA microarray data, miR-224 was identified as the most upregulated miRNA in cisplatin (DDP; cis-diamminedichloroplatinum II)-resistant A549 cells compared with parental A549 cells. The aim of our study was to investigate the roles of miR-224 in the formation of DDP-resistant phenotype of LA cells and its possible molecular mechanisms.

Results:

Here we showed that miR-224 could promote the in vitro and in vivo DDP resistance of LA cells via regulating G₁/S cell cycle transition and apoptosis. p21^WAF1/CIP1, a potent cyclin-dependent kinase inhibitor, was identified as the direct and functional target gene of miR-224. Overexpression of p21^WAF1/CIP1 could phenocopy the effect of miR-224 downregulation and silencing of p21^WAF1/CIP1 could partially reverse the effect of miR-224 downregulation on DDP resistance of DDP-resistant LA cells. In addition, miR-224 could affect the G₁/S transition of cell cycle and apoptosis in LA cells through the p21^WAF1/CIP1-pRb pathway and the intrinsic mitochondrial death pathway. Furthermore, miR-224 was found to be downregulated in DDP-responding LA tissues, and its expression was inversely correlated with p21^WAF1/CIP1. Multivariate analyses indicated that the status of miR-224 might be an independent prognostic factor for predicting the survival of LA patients.

Conclusions:

Our findings shed novel light on the roles of miR-224/p21^WAF1/CIP1 signalling in the DDP resistance of LA cells, and targeting it will be a potential strategic approach for reversing the DDP resistance in human LAs.     

Age-related difference in susceptibility of Apc(Min/+) mice towards the chemopreventive efficacy of dietary aspirin and curcumin

The nonsteroidal anti-inflammatory drug aspirin and the spice curcumin retard adenoma formation when administered long-term to Apc(Min/+) mice, a model of human familial adenomatous polyposis coli. Both agents interfere with cyclooxygenase activity. When aspirin is administered to Apc(Min/+) mice only postweaning, but not before, it is inefficacious, while curcumin given postweaning is active. Here the hypothesis was tested that dietary aspirin (0.05%) or curcumin (0.2%) prevent or delay adenoma formation in offsprings when administered to Apc(Min/+) mothers and up to the end of weaning, but not afterwards. Whereas curcumin was without effect when administered in this way, aspirin reduced numbers of intestinal adenomas by 21%. When aspirin given up to the end of weaning was combined with curcumin administered from the end of weaning for the rest of the animals' lifetime, intestinal adenoma numbers were reduced by 38%. The combination was not superior to intervention postweaning with curcumin alone. These results show that aspirin exerts chemopreventive activity in the Apc(Min/+) mouse during tumour initiation/early promotion, while curcumin is efficacious when given at a later stage of carcinogenic progression. Thus, the results suggest that in this mouse model aspirin and curcumin act during different 'windows' of neoplastic development.     

c-Myc alters the DNA damage-induced G2/M arrest in human mammary epithelial cells

Effects of c-Myc overexpression on the DNA damage-induced G2/M checkpoint were studied in finite lifespan, normal human mammary epithelial cells (HMECs). Previously, we showed that c-Myc attenuates G1/S arrest and leads to an inappropriate entry of cells with damaged DNA into the S phase, following treatment with ionising radiation (IR). Here we show that, in striking contrast to control cells, c-Myc-overexpressing HMECs demonstrate a significant attenuation of the G2/M arrest, following IR, and enter into inappropriate mitoses. At the molecular level, ectopic overexpression of c-Myc leads to an unusually high level of expression of cyclin B1, and the elevated levels of cyclin B1 were maintained, after gamma-irradiation. Introduction of DNA damage in c-Myc-overexpressing, normal mammary epithelial cells eventually induces apoptosis, indicating a dramatic sensitisation by c-Myc of DNA damage-induced apoptosis. These two remarkable phenotypes, checkpoint attenuation and sensitisation to apoptosis, resulting from a deregulation of the protooncogene c-myc, may produce a unique pattern of alternating cycles, consisting first of amplification of DNA damage, followed by apoptosis-assisted selective pressure. The result of this alternating pattern of damage apoptosis could facilitate the selection of certain genomic alterations required for cellular survival and cellular transformation.