Frequent loss of expression of the cyclin-dependent kinase inhibitor p27 in epithelial ovarian cancer.

p27Kip1 is a member of the Cip1/Kip1 family of cyclin-dependent kinase inhibitors and is a potential tumor suppressor gene. Low levels of p27 are associated with poor prognosis in a variety of tumors, including breast, colon, prostate, and lung carcinomas. In the present study, p27 protein expression was investigated by immunohistochemistry and Western blot analysis in a series of 82 epithelial ovarian tumors [16 classified as low malignant potential (LMP) and 66 classified as primary ovarian adenocarcinomas]. Immunohistochemical analysis revealed frequent loss of p27 expression in primary ovarian adenocarcinomas (33%), with respect to LMP tumors (6%; P = 0.0009). In addition to nuclear staining, cytoplasmic localization of p27 was noted in 45 (55%) of 82 cases. p27 levels inversely correlated with cdk2 kinase activity in a representative subset of tumors. When the clinical outcome of the patients was evaluated in relationship to p27 status, we observed a significant correlation between presence of p27 staining and a longer time to progression (P = 0.032 by log-rank test). These data indicate that loss of p27 is a frequent event in ovarian carcinomas as compared with LMP tumors, suggesting that these tumor types may have different pathogenesis. p27 levels may also represent a useful prognostic marker for predicting disease recurrence in primary ovarian carcinomas.     

Frequent loss of expression of the cyclin-dependent kinase inhibitor p27(Kip1) in estrogen-related Endometrial adenocarcinomas.

PURPOSE: p27(Kip1) is a member of the Cip1/Kip1 family of cyclin-dependent kinase inhibitors and is a potential tumor suppressor gene. Low levels of p27 are associated with poor prognosis in a variety of gynecological tumors, including breast, ovarian, and cervical carcinomas. The role of p27 in endometrial cancer remains controversial. EXPERIMENTAL DESIGN: In the present study, p27 protein expression was investigated by immunohistochemistry in a series of 217 endometrial adenocarcinomas and, where present, in synchronous normal endometrium, simple and complex hyperplasia (with or without atypia), and cystic atrophy. The relationship between p27 expression and clinical outcome was also evaluated. RESULTS: Immunohistochemical analysis revealed a significant loss of p27 expression from normal (33%) through hyperplastic endometrium (50%) to endometrial adenocarcinomas (71%; P 相似文献   

The proteasome inhibitor PS-341 inhibits growth, induces apoptosis, and overcomes drug resistance in human multiple myeloma cells

Human multiple myeloma (MM) is a presently incurable hematological malignancy, and novel biologically based therapies are urgently needed. Proteasome inhibitors represent a novel potential anticancer therapy. In this study, we demonstrate that the proteasome inhibitor PS-341 directly inhibits proliferation and induces apoptosis of human MM cell lines and freshly isolated patient MM cells; inhibits mitogen-activated protein kinase growth signaling in MM cells; induces apoptosis despite induction of p21 and p27 in both p53 wild-type and p53 mutant MM cells; overcomes drug resistance; adds to the anti-MM activity of dexamethasone; and overcomes the resistance to apoptosis in MM cells conferred by interleukin-6. PS-341 also inhibits the paracrine growth of human MM cells by decreasing their adherence to bone marrow stromal cells (BMSCs) and related nuclear factor kappaB-dependent induction of interleukin-6 secretion in BMSCs, as well as inhibiting proliferation and growth signaling of residual adherent MM cells. These data, therefore, demonstrate that PS-341 both acts directly on MM cells and alters cellular interactions and cytokine secretion in the BM millieu to inhibit tumor cell growth, induce apoptosis, and overcome drug resistance. Given the acceptable animal and human toxicity profile of PS-341, these studies provide the framework for clinical evaluation of PS-341 to improve outcome for patients with this universally fatal hematological malignancy.     

Farnesyltransferase inhibitor R115777 inhibits cell growth and induces apoptosis in mantle cell lymphoma

Introduction The cytotoxic activity of the farnesyltranseferase inhibitor R115777 was evaluated in cell lines representative of mantle cell lymphoma (MCL). Methods Cell growth, proliferation, and apoptosis were analyzed in four human MCL cell lines (Granta, NCEB, REC, and UPN1) in presence of R115777, alone or in combination with vincristin, doxorubicin, bortezomib, cisplatin and cytarabine. Inhibition of farnesylation was determined by the appearance of prelamin A. The antitumor activity of R115777, administered p.o. at 100, 250 and 500mg/kg, was determined in vivo in nude mice xenografted with UPN1 cells. Results R115777 inhibited the growth of MCL cell lines in vitro with inhibitory concentrations ranging between 2 and 15nM. A fifty percent decrease of cell viability was observed at concentrations comprised between 0.08 and 17μM. Apoptosis, evaluated by annexin V and activated caspase 3 staining, was induced in all cell lines, in 40 to 71% of the cells depending on the cell lines. In addition, R115777 significantly increased the cytotoxic effect of vincristine, doxorubicin, bortezomib, cisplatin and cytarabine (p=0.001, p=0.016, p=0.006, p=0.014 and p=0.007 respectively). Exposure of MCL cell lines to R115777 during 72 hours resulted in inhibition of protein farnesylation. R115777 administered p.o. twice daily for 8 consecutive days to mice bearing established s.c. UPN1 xenograft displayed cytostatic activity at the 500 mg/kg dosage. Conclusion We have demonstrated that inhibition of farnesyltransferase by R115777 was associated with growth inhibition and apoptosis of MCL cell lines in vitro and tumor xenograft stability in vivo.     

Nitric oxide induces cyclooxygenase expression and inhibits cell growth in colon cancer cell lines

The role of nitric oxide (NO) in colon cancer remains controversial. Inducible nitric oxide synthase (iNOS) has been reported to be up regulated and down regulated in colorectal cancer in both animal models and patient tissue samples. Cyclooxygenase-2 (COX-2) is important in colorectal carcinogenesis but its relationship with NO has never been studied in colon cancer. Three colon cancer cell lines (HCA7, HT29 and HCT116) with different COX-2 expression and activities were used to study the effect of the NO donor, S-nitrosoglutathione (GSNO). The effects of GSNO (10-500 micro M) on cell growth, PGE(2) production, COX-1/COX-2 protein expression and cell-cycle distribution were evaluated. GSNO increased PGE(2) production and induced COX-1 and COX-2 protein expression in a dose- and time-dependent manner. Higher concentrations of GSNO also inhibited cell growth and induced apoptosis in all three cell lines, regardless of their COX-2 expression/activities. Inhibition of PGE(2) production did not further improve the inhibitory effect of GSNO.     

The farnesyl transferase inhibitor, FTI-277, inhibits growth and induces apoptosis in drug-resistant myeloma tumor cells.

Mutations of the ras gene are among the most commonly identified transforming events in human cancers, including multiple myeloma. Farnesyltransferase inhibitors (FTI) were developed to prevent Ras processing and induce cancer cell death. Several FTIs are in phase II and one is in phase III clinical trials. Preclinically, most of the focus has been on solid tumors, and the effects of FTIs in multiple myeloma have not been investigated. In this study we examined the cytotoxic activity and inhibition of Ras processing in three myeloma cell lines with differing Ras mutation status. H929 cells with activated N-Ras were more sensitive to FTI-277 treatment than 8226 and U266 cells with activated K-Ras or wild-type Ras, respectively. A combination of FTI-277 and a geranylgeranyltransferase I inhibitor (GGTI)-2166 inhibited K-Ras processing and enhanced cell death in 8226 cells. U266 cells and Bcl-x(L) transfectants were equally sensitive to FTI-277 treatment. Similarly, 8226 cells selected for resistance to various chemotherapeutic agents, which resulted in either P-glycoprotein overexpression, altered topoisomerase II activity, or elevated glutathione levels, were equally sensitive to FTI-277. These preclinical studies suggest that prenylation inhibitors may represent new therapeutic agents for the treatment of refractory or drug-resistant multiple myeloma.     

Arsenic trioxide-mediated growth inhibition in MC/CAR myeloma cells via cell cycle arrest in association with induction of cyclin-dependent kinase inhibitor, p21, and apoptosis

We investigated the in vitro effect of As2O3 on proliferation, cell cycle regulation, and apoptosis in human myeloma cell lines. As2O3 significantly inhibited the proliferation of all of eight myeloma cell lines examined in a dose-dependent manner with IC50 of approximately 1-2 microM. DNA flow cytometric analysis indicated that As2O3 (2 microM) induced a G1 and/or a G2-M phase arrest in these cell lines. To address the mechanism of the antiproliferative effect of As2O3, we examined the effect of As2O3 on cell cycle-related proteins in MC/CAR cells in which both G1 and G2-M phases were arrested. Western blot analysis demonstrated that treatment with As2O3 (2 microM) for 72 h did not change the steady-state levels of CDK2, CDK4, cyclin D1, cyclin E, and cyclin B1 but decreased the levels of CDK6, cdc2, and cyclin A. The mRNA and protein levels of CDKI, p21 were increased by treatment with As2O3, but those of p27 were not. In addition, As2O3 markedly enhanced the binding of p21 with CDK6, cdc2, cyclin E, and cyclin A compared with untreated control cells. Furthermore, the activity of CDK6-associated kinase was reduced in association with hypophosphorylation of Rb protein. The activity of cdc2-associated kinase was decreased, which was accompanied by the up-regulation of cdc2 phosphorylation (cdc2-Tyr15 phosphorylation) resulting from reduction of cdc25B and cdc25C phosphatases. As2O3 also induced apoptosis in MC/CAR cells as evidenced by flow cytometric detection of sub-G1 DNA content and annexin V binding assay. This apoptotic process was associated with down-regulation of Bcl-2, loss of mitochondrial transmembrane potential (delta psi(m)), and an increase of caspase-3 activity. These results suggest that As2O3 inhibits the proliferation of myeloma cells, especially MC/CAR cells, via cell cycle arrest in association with induction of p21 and apoptosis.     

Frequent p16 inactivation by homozygous deletion or methylation is associated with a poor prognosis in Japanese patients with pleural mesothelioma

This study examined the p16 expression status and the P16 gene deletion and methylation status in specimens from Japanese patients with malignant pleural mesothelioma (MPM). Immunohistochemical staining for p16 protein and fluorescence in situ hybridization for the P16 gene were performed using specimens from 30 Japanese patients with primary MPM. The methylation status of the P16 gene was examined in 13 patients whose frozen tumor specimens were available using a methylation-specific PCR assay. Among the 30 patients, the loss of p16 protein expression was observed in 24 patients (80.0%). Twenty-one patients had homozygous deletions, and 9 patients retained the P16 gene. None of the patients with P16 homozygous deletions exhibited p16-positive expression, and 3 patients who retained the P16 gene did not exhibit p16-positive expression. Aberrant P16 methylation was present in two patients with an intact P16 gene but without p16 expression. These results suggest that either a homozygous deletion or methylation is responsible for P16 inactivation. Regarding the prognosis, patients with p16-negative expression had a significantly shorter survival time than those with p16-positive expression (P=0.040). Our study showed that P16 inactivation by homozygous deletions or methylation is a frequent event in Japanese patients with MPMs, relating to poor prognosis. Homozygous deletion is the major cause of P16 inactivation, but methylation also lead to the inactivation of P16 when the P16 alleles are retained.     

Over-expression of p27kip1 induces growth arrest and apoptosis mediated by changes of pRb expression in lung cancer cell lines

p27kip1 is a cyclin-dependent kinase inhibitor which controls the G1 phase of the cell cycle in conjunction with pRb. p27 has been associated with cell-cycle arrest and apoptosis. In this study, we transferred the full-length human p27 cDNA using a replication-deficient recombinant adenoviral vector (Ax-p27) into lung cancer cell lines and evaluated the potential of this strategy for anti-cancer gene therapy. After infection with Ax-p27, the growth of H322, A549 and SQ-5 cells, which express pRb, was almost completely suppressed, though no such effect was found in H69 and Lu-135 cells, which do not express pRb. In addition, cell death from day 4 after infection with Ax-p27 was observed only in H322, A549 and SQ-5 cells but not in H69 and Lu-135 cells. The cell cycle of H322 cells treated with Ax-p27 became arrested at the G1 phase from day 1 to day 3 despite continued over-expression of p27. When we examined the changes in expression level of pRb and E2F-1, which play important roles in cell-cycle progression from G1 to S phase, down-regulation of pRb expression was detected in H322 cells 3 days after infection with Ax-p27. These data suggest that (i) the growth-inhibitory effect and induction of apoptosis by over-expression of p27 require expression of pRb and (ii) adenovirus-mediated p27 gene transfer may have promise as a novel strategy in cancer gene therapy.     

N-benzoylstaurosporine (PKC412) inhibits Akt kinase inducing apoptosis in multiple myeloma cells.

Multiple myeloma is a clonal malignancy of plasma cells that invariably progresses to a chemoresistant state. The PI3K/Akt pathway mediates signals downstream of several growth factors involved in myeloma pathogenesis, and constitutive activation of Akt was observed in myeloma cells. We now report that a staurosporine derivative, N-benzoylated staurosporine or PKC412, induces cell death in myeloma cell lines (RPMI8226S, U266, MM1S and MM1R) with loss of mitochondrial membrane potential Delta psi m, caspase 3 and PARP cleavage. ZVAD.fmk, but not interleukin-6, rescued these cells from PKC412 effects. Upstream of the mitochondria, PKC412 inhibited Bad phosphorylation and attenuated Akt kinase activity by suppressing its phosphorylation on serine residue in its activation loop. Reduced phosphorylation of downstream Akt substrates GSK3 alpha/beta and FKHR was also noted. Stable transfection of 8226S cells with constitutively active Akt (8226S-myAkt) partially protected against PKC412 cytotoxicity. Primary myeloma cells isolated from refractory myeloma patients (n=4), were equally sensitive to PKC412 treatment. More importantly, PKC412 did not affect CFU-GM or BFU-E colony formation. In summary, our results demonstrate that PKC412 suppresses Akt kinase activation and induces apoptosis in myeloma cell lines, as well as primary resistant cells. PKC412 is an appropriate candidate for novel treatment protocols for multiple myeloma.     

A thioredoxin reductase inhibitor induces growth inhibition and apoptosis in five cultured human carcinoma cell lines

Human thioredoxin reductase (TrxR) system is associated with cancer cell growth and anti-apoptosis process. Effects of 1, 2-[bis (1,2-Benzisoselenazolone-3 (2H) -ketone)]ethane (BBSKE), a novel TrxR inhibitor, were investigated on A549, HeLa, Bel-7402, BGC823 and KB cell lines. After treated with BBSKE, a good linear correlation coefficient (r>or=0.989) between TrxR activity and cell viability exists in each cell line together with cell growth/proliferation inhibition and apoptosis through Bcl-2/Bax and Caspase-3 pathways. These results suggest that there exists some relationship between TrxR inactivation and growth/proliferation inhibition or apoptosis in the investigated cell lines.     

Sustained activation of c-jun-N-terminal kinase plays a critical role in arsenic trioxide-induced cell apoptosis in multiple myeloma cell lines

Multiple myeloma (MM) is a presently incurable B-cell malignancy, and newer biologically based therapies are needed. Arsenic trioxide (ATO) has been established as a therapeutic agent for relapsed acute promyelocytic leukemia patients, and has been used for MM patients in clinical trials. In this study, we investigated the role of c-jun-N-terminal kinase (JNK) in ATO-induced apoptosis in MM lines. The exogenous interleukin (IL)-6 dependent MM line, ILKM-3, and independent MM lines, U266 and XG-7, were treated with a therapeutic concentration of ATO with or without JNK inhibitor 1 (a JNK-specific inhibitor) and anisomycin (a JNK activator). Their cell growth, cell cycle, JNK activation and NF-kappaB activation were investigated. ATO induced apoptosis in U266 and ILKM-3 regardless of their exogenous IL-6 dependency. This apoptosis, accompanied with decreased mitochondrial transmembrane potential, sustained activation of JNK but not cell cycle arrest. Pretreatment of JNK inhibitor prevented ATO-induced apoptosis in ATO-sensitive lines. Combined treatment with ATO and anisomycin induced sustained activation of JNK and apoptosis in the ATO-insensitive MM line, XG-7. Results of various time period treatments of ATO showed that sustained activation of JNK was needed in ATO-induced apoptosis in MM. IkBalpha phosphorylation was not associated with ATO-sensitivity of MM lines. These findings suggest that sustained activation of JNK plays a critical role in ATO-induced apoptosis in MM cell lines. Cotreatment with ATO and the agent, which can induce sustained activation of JNK, might improve the outcome in MM therapy.     

A new indole-3-carbinol tetrameric derivative inhibits cyclin-dependent kinase 6 expression,and induces G1 cell cycle arrest in both estrogen-dependent and estrogen-independent breast cancer cell lines

Indole-3-carbinol (I3C), autolysis product of glucosinolates present in cruciferous vegetables, has been indicated as a promising agent in preventing the development and progression of breast cancer. I3C has been shown to inhibit the growth of human cancer cells in vitro and possesses anticarcinogenic activity in vivo. Because I3C is unstable and may be converted into many polymeric products in the digestive tract, it is not yet clear whether the biological activity observed can be attributed to I3C or some of its polymeric products. In this study we synthesized a stable I3C cyclic tetrameric derivative and investigated its effects on a panel of human breast cancer cell lines. The I3C tetramer suppressed the growth of both estrogen receptor (ER) -positive (MCF-7, 734B, and BT474) and ER-negative (BT20, MDA-MB-231, and BT539) human breast cancer cell lines, and it was found to induce G(1) cell cycle arrest in a dose-dependent manner without evidence of apoptosis, suggesting a growth arrest via a cytostatic mechanism. At the molecular level, the tetramer inhibited cyclin-dependent kinase (CDK) 6 expression and activity, induced an increase in the level of p27(kip1), and reduced the level of retinoblastoma protein expression. Contrarily to CDK6, the level of CDK4, the other kinase involved in the G(1) phase of the cell cycle, remains unchanged. Interestingly, the tetramer resulted about five times more active than I3C in suppressing the growth of human breast cancer cells. On the whole, our data suggest that the I3C tetrameric derivative is a novel lead inhibitor of breast cancer cell growth that may be a considered a new, promising therapeutic agent for both ER+ and ER- breast cancer.