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Domenico Coppola

Publications and source records attributed to Domenico Coppola.

At least 19 recordsLinked to original sources
PubMed2004

Blocking angiogenesis and tumorigenesis with GFA-116, a synthetic molecule that inhibits binding of vascular endothelial growth factor to its receptor.

A small synthetic library of cyclohexapeptidomimetic calixarenes was prepared to identify disrupters of vascular endothelial growth factor (VEGF) binding to its receptor that inhibits angiogenesis. From this library, we discovered GFA-116, which potently inhibits (125)I-VEGF binding to Flk-1 in Flk-1-overexpressing NIH 3T3 cells and human prostate tumor cells with an IC(50) of 750 nM. This inhibition is highly selective for VEGF in that (125)I- platelet-derived growth factor binding to its receptor is not affected. GFA-116 inhibits VEGF-stimulated Flk-1 tyrosine phosphorylation and subsequent activation of Erk1/2 mitogen-activated protein kinases. Furthermore, epidermal growth factor, platelet-derived growth factor, and fibroblast growth factor-dependent stimulation of Erk1/2 phosphorylation are not affected at concentrations as high as 10 microM. In vitro, GFA-116 inhibits angiogenesis as measured by inhibition of migration and formation of capillary-like structures by human endothelial cells as well as suppression of microvessel outgrowth in rat aortic rings and rat cornea angiogenesis. In vivo, GFA-116 (50 mpk/day) inhibits tumor growth and angiogenesis as measured by CD31 staining of A-549 human lung tumors in nude mice. Furthermore, GFA-116 is also effective at inhibiting tumor growth and metastasis to the lung of B16-F10 melanoma cells injected into immunocompetent mice. Taken together, these results demonstrate that a synthetic molecule capable of disrupting the binding of VEGF to its receptor selectively inhibits VEGF-dependent signaling and suppresses angiogenesis and tumorigenesis.

Angiogenesis Inhibitors↗
PubMed2004

Cytology of human ovarian surface epithelial brushings.

BACKGROUND: The human ovarian surface epithelium (HOSE) is the putative source of ovarian epithelial cancer, the most lethal gynecologic malignancy that affects women in the United States. The current study was designed to provide a database of normal HOSE cell features for diagnostic and research applications. METHODS: HOSE was harvested from 42 women undergoing laparoscopy or laparotomy for benign gynecologic disorders, infertility problems, or pregnancy. Of the 42 women, 12 were postovulatory and 20 were receiving hormonal regimens. Cells were harvested with a sterile brush inserted through a laparoscopic port or with a sterile cell scraper at laparotomy. RESULTS: Two HOSE populations were identified, ranging in size from 8 to 10 microm and from 15 to 20 microm, respectively. The cells measuring 15-20 microm exhibited slight anisonucleosis, more prominent nucleoli, fine cytoplasmic metachromasia, and an overall reparative or squamoid morphology. Cells were single or arranged in small clusters, sheets, or papillae. They coexpressed cytokeratin and vimentin but did not overexpress p53. Cellularity and proliferation (up to 3.2% +/- 0.8) were higher and papillae more frequent in postovulatory and cyst-bearing ovaries, including polycystic ovaries, suggesting underlying ovarian or hormonal influences. Representative HOSE brushings yielded a mean of 23,133 cells per patient (range, 4250-64,500 cells), equivalent to an estimated 0.58, 0.46, and 0.14 microg of nuclear protein, cell RNA, and nuclear DNA, respectively. Within 7-10 days of explantation, HOSE cells formed confluent monolayers with immunohistochemical and ultrastructural epithelial features. CONCLUSIONS: The current study defined baseline features of HOSE cells important to pathologists and clinicians evaluating women at risk for ovarian epithelial cancer and to researchers investigating the pathobiology of this aggressive gynecologic malignancy.

Adult↗
PubMed2004

Phosphatidylinositol-3-OH kinase/AKT and survivin pathways as critical targets for geranylgeranyltransferase I inhibitor-induced apoptosis.

Geranylgeranyltransferase I inhibitors (GGTIs) represent a new class of anticancer drugs. However, the mechanism by which GGTIs inhibit tumor cell growth is still unclear. Here, we demonstrate that GGTI-298 and GGTI-2166 induce apoptosis in both cisplatin-sensitive and -resistant human ovarian epithelial cancer cells by inhibition of PI3K/AKT and survivin pathways. Following GGTI-298 or GGTI-2166 treatment, kinase levels of PI3K and AKT were decreased and survivin expression was significantly reduced. Ectopic expression of constitutively active AKT2 and/or survivin significantly rescue human cancer cells from GGTI-298-induced apoptosis. Previous studies have shown that Akt mediates growth factor-induced survivin, whereas p53 inhibits survivin expression. However, constitutively active AKT2 failed to rescue the GGTIs downregulation of survivin. Further, GGTIs suppress survivin expression and induce programmed cell death in both wild-type p53 and p53-deficient ovarian cancer cell lines. These data indicate that GGTI-298 and GGTI-2166 induce apoptosis by targeting PI3K/AKT and survivin parallel pathways independent of p53. Owing to the fact that upregulation of Akt and survivin as well as inactivation of p53 are frequently associated with chemoresistance, GGTIs could be valuable agents to overcome antitumor drug resistance.

Alkyl and Aryl Transferases↗
PubMed2004

Correlation of osteopontin protein expression and pathological stage across a wide variety of tumor histologies.

PURPOSE: Osteopontin (OPN) is an integrin-binding protein overexpressed in various experimental models of malignancy and appears to be involved in tumorigenesis and metastasis. Although various studies have assessed OPN protein levels in several tumor types, a broad survey of OPN expression in human neoplasia under the same experimental conditions has not been carried out. EXPERIMENTAL DESIGN: We used immunohistochemistry to detect OPN in a selection of 350 human tumors and 113 normal tissues, from a variety of body sites, using stage-oriented human cancer tissue arrays. Tumors included malignancies from breast (26), ovary (22), endometrium (14), esophagus (10), stomach (11), pancreas (16), bile duct (1), liver (9), colon (20), kidney (53), bladder (33), prostate (28), head and neck (60), salivary glands (14), lung (17), skin (6), and brain (10). RESULTS: High cytoplasmic OPN staining was observed in 100% of gastric carcinomas, 85% of colorectal carcinomas, 82% of transitional cell carcinomas of the renal pelvis, 81% of pancreatic carcinomas, 72% of renal cell carcinomas, 71% of lung and endometrial carcinomas, 70% of esophageal carcinomas, 58% of squamous cell carcinomas of the head and neck, and 59% of ovarian carcinomas. Although OPN expression was identified in a good number of bladder, prostate, and brain tumors, the majority of 6 skin cancers, 11 of 14 salivary gland cancers, 2 thyroid carcinomas, and 23 of 26 breast cancers revealed low OPN positivity or were negative. When considering all sites, OPN expression significantly correlated with tumor stage (Spearman's correlation coefficient, P = 0.0002). OPN score and stage were also significantly correlated for specific cancer sites including bladder (P = 0.01), colon (P = 0.004), kidney (P = 0.0001), larynx (P = 0.035), mouth (P = 0.046), and salivary gland (P = 0.011). CONCLUSIONS: This study reports the broad distribution of OPN in human tumors from different body sites, suggesting involvement of this protein in tumor formation. The strong correlation between pathological stage and OPN across multiple tumor types suggests a role for OPN in tumor progression.

Aged↗
PubMed2004

Flat and polypoid adenocarcinomas of the colorectum: A comparative histomorphologic analysis of 47 cases.

"Flat" colorectal adenomas and adenocarcinomas are well documented in the Japanese literature but only sporadically reported in the English literature. The present study involved systematic morphological analysis of a large series of colorectal carcinomas (CRCs) to determine the frequency of these "flat" CRCs (FCRCs) and analyze their pathological characteristics and associated patient survival. The study group comprised 47 patients (19 females and 28 males) with primary CRC who underwent colorectal resection at the H. Lee Moffitt Cancer Center between 1997 and 2002. These cases were selected based on the gross appearance of the tumors and after review of all of the hematoxylin and eosin-stained tumor sections in a series of 190 consecutive colorectal resections for CRCs. Application of strict morphological criteria classified 22 tumors as FCRCs. For comparison, 25 "polypoid" CRCs (PCRCs) were also identified. Cases of ulcerative fungating annular CRCs and CRCs with mixed gross appearance were excluded from this analysis. Clinicopathologic data, including patient survival, were compared for FCRCS and PCRCs. Statistical analyses were carried out using the chi(2) or Fisher's exact test and log-rank tests. Overall, 22 of 190 CRCs (11%) were found to meet the morphological criteria of FCRCs. Mean patient age was 70.6 years (range, 55 to 87) for FCRCs versus 68.5 years (range, 54 to 91) for PCRCs, and mean tumor size was 4.7 cm (range, 1.6 to 9) for FCRCs versus 4.4 cm (range, 0.5 to 10) for PCRCs. None of the 22 FCRCs and only 1 of 25 (4%) PCRCs were well differentiated; 17 of 22 (77%) FCRCs and 23 of 25 (92%) PCRCs were moderately differentiated; and 5 of 22 (22%) FCRCs and 1 of 25 (4%) PCRCs were poorly differentiated (P = 0.0087). FCRC cases were staged as 0 stage T1, 3 (14%) stage T2, and 19 (86%) stage T3; PCRC cases, as 4 (16%) stage T1, 14 (56%) stage T2, and 7 (28%) stage 3 (P = 0.000031). Similarly, angiolymphatic invasion was identified in 12 of 22 (54%) FCRCs versus 4 of 25 (16%) PCRCs (P = 0.0123). Although some differences between FCRCs and PCRCs were observed on resection in terms of nodal status (N), presence of metastases (M), and perineural invasion, these differences were not statistically significant. In comparison with PCRCs, FCRCs were associated with significantly shorter postresection patient survival at 1 to 5 years (P = 0.028). We have demonstrated in this report that a proportion of primary CRCs resected at our institution were indeed "flat." Furthermore, these FCRCs exhibited higher histological grades, higher T stage, more frequent angiolymphatic invasion, and shorter patient survival compared with PCRCs. Based on these data, FCRC appears to be a worse subtype of colon cancer than PCRC. Further appraisal of FCRCs and additional studies to further elucidate the molecular mechanisms underlying their morphogenesis are warranted.

Adenocarcinoma↗
PubMed2004

The expression of insulin-like growth factor-I receptor correlates with Fuhrman grading of renal cell carcinomas.

Recent reports have shown significant correlation between Fuhrman nuclear grade of renal cell carcinoma (RCC) and patient survival. However, no one specific gene alteration has yet been described to account for this correlation. This study investigated the expression of the insulin-like growth factor-I receptor (IGF-IR) in RCC and correlated the results to the tumor Fuhrman nuclear grade. Formalin-fixed, paraffin-embedded sections from 68 cases of RCC were stained using the immunohistochemical avidin-biotin-peroxidase method. An anti-human IGF-IR rabbit polyclonal antibody was used. The stains were semiquantitatively evaluated using the Allred score system, assessing intensity of stain and percentage of positive tumor cells. Statistical analysis was performed using the Kruskal-Wallis test. Strong and diffuse cytoplasmic IGF-IR stain (Allred score 7 to 8) was identified in 25 of 25 (100%) of grade 3 and 4 RCCs. Grade 2 RCCs had a median IGF-IR Allred score of 4. Ten of 10 (100%) grade 1 RCCs were negative. Even in the positive high-nuclear-grade tumors, areas of low nuclear grade, when present, were IGF-IR negative. Statistical analysis using the Kruskal-Wallis test demonstrated significant correlation between increasing Fuhrman nuclear grade and increasing IGF-IR Allred score (P <0.0001). Thus we report the novel finding of significant statistical correlation between IGF-IR protein expression and Fuhrman nuclear grade of RCC, and consequentially with patient survival.

Adult↗
PubMed2004

Multi-platform, multi-site, microarray-based human tumor classification.

The introduction of gene expression profiling has resulted in the production of rich human data sets with potential for deciphering tumor diagnosis, prognosis, and therapy. Here we demonstrate how artificial neural networks (ANNs) can be applied to two completely different microarray platforms (cDNA and oligonucleotide), or a combination of both, to build tumor classifiers capable of deciphering the identity of most human cancers. First, 78 tumors representing eight different types of histologically similar adenocarcinoma, were evaluated with a 32k cDNA microarray and correctly classified by a cDNA-based ANN, using independent training and test sets, with a mean accuracy of 83%. To expand our approach, oligonucleotide data derived from six independent performance sites, representing 463 tumors and 21 tumor types, were assembled, normalized, and scaled. An oligonucleotide-based ANN, trained on a random fraction of the tumors (n = 343), was 88% accurate in predicting known pathological origin of the remaining fraction of tumors (n = 120) not exposed to the training algorithm. Finally, a mixed-platform classifier using a combination of both cDNA and oligonucleotide microarray data from seven performance sites, normalized and scaled from a large and diverse tumor set (n = 539), produced similar results (85% accuracy) on independent test sets. Further validation of our classifiers was achieved by accurately (84%) predicting the known primary site of origin for an independent set of metastatic lesions (n = 50), resected from brain, lung, and liver, potentially addressing the vexing classification problems imposed by unknown primary cancers. These cDNA- and oligonucleotide-based classifiers provide a first proof of principle that data derived from multiple platforms and performance sites can be exploited to build multi-tissue tumor classifiers.

Algorithms↗
PubMed2004

Inhibition of angiogenesis by Abeta peptides.

Abeta peptides are naturally occurring peptides forming beta-sheet aggregates that constitute an integral component of senile plaques and vascular deposits in Alzheimer's disease. Since several peptides adopting a beta-sheet conformation have been shown to be anti-angiogenic, we investigated the effect of Abeta on angiogenesis. We show that in vitro, Abeta dose-dependently inhibits the formation of capillaries by human brain endothelial cells plated on Matrigel and stimulates capillary degeneration at high doses. Preparations of Abeta peptides containing a higher content of beta-sheet structures are more potently anti-angiogenic in vitro. Ex vivo, Abeta dose-dependently opposes angiogenesis in rat aortae and in human middle cerebral arteries. In vivo, Abeta dose dependently inhibits angiogenesis in the chick chorioallantoic membrane assay and suppresses bFGF-induced blood vessel formation in the corneal micropocket and Matrigel plug assays. Since angiogenesis is required for tumor growth, we explored the effect of Abeta on human glioblastoma (U87MG) and human lung adenocarcinoma (A549) tumors. We show that intra-tumoral injection of Abeta potently inhibits the growth and vascularization of human glioblastoma and human lung adenocarcinoma tumor xenografts in nude mice. Similarly to the intra-tumoral injection regimen, Abeta delivered intraperitoneally also suppressed the growth of human lung adenocarcinoma tumor xenografts. Altogether our data show that Abeta is an angiogenesis inhibitor.

Amyloid beta-Peptides↗
PubMed2004

Cyclooxygenase-2 expression in right- and left-sided colon cancer: a rationale for optimization of cyclooxygenase-2 inhibitor therapy.

Cyclooxygenase-2 (COX-2) has been identified as a potential target for prevention and therapy of human colorectal cancers (CRC) and other cancers. Because right-sided colon cancers (RSCCs) exhibit clinicopathologic and genetic differences from left-sided colorectal cancers (LSCRCs), determination of COX-2 status in these subsets of CRCs may be clinically relevant in designing COX-2 inhibitor trials for CRC and in subsequent assessment of objective therapeutic response to such therapy. Thirty-six primary CRC resection specimens (18 left, 18 right) from 36 patients were evaluated. Representative tumor sections were subjected to immunohistochemical analysis of COX-2. A semiquantitative system was used to score cytoplasmic COX-2 immunostaining. The tumors were considered COX-2 positive if more than 10% tumor cells showed COX-2 staining. Clinicopathologic and COX-2 data were compared for LSCRCs versus RSCCs. All 18 LSCRCs and 13 of 18 (72%) RSCCs were well to moderately differentiated. Overall rates of COX-2 positivity for the LSCRCs versus RSCCs were 67% (12 of 18) and 33% (6 of 18), respectively (P = 0.04). Furthermore, 11 of 12 (92%) COX-2 positive LSCRCs and 3 of 6 (50%) COX-2 positive RSCCs were stage II-IV at resection. All 12 COX-2 positive LSCRCs were associated with advanced primary tumor and 4 of 12 (33%) LCRCs had distant metastases. These associations could not be evaluated for the RSCCs because of the limited number of COX-2 positive cases. The more frequent expression of COX-2 in LSCRCs as compared with RSCCs supports the hypothesis that COX-2 expression may be related to genetic alterations specific to right- or left-sided CRCs. Further studies are needed to elucidate such relationships. Our data also suggest that stratification of patients with CRC into right- and left-sided subsets may be important in optimal patient selection for COX-2 inhibitor therapy and for subsequent assessment of objective therapeutic response.

Adult↗
PubMed2004

Search for epithelial-specific mRNAs in peripheral blood of patients with colon cancer by RT-PCR.

Research has widely supported the efficacy of screening for colorectal cancer in reducing mortality. A blood-based assay potentially represents a more accessible early detection tool for the identification of solid tumor cells originating from a primary tumor site in the body. We demonstrate a relatively easy and highly reproducible technique for the detection of mRNA expression of genes as markers of malignancy in blood samples of patients with colon cancer. The present study aims to identify a set of specific mRNAs expressed in epithelial cells but not in blood cells, which may be useful as markers for early detection of circulating colon cancer cells by a simple, qualitative RT-PCR assay following semi-automated RNA extraction from peripheral blood samples. Our approach includes a systematic search for candidate markers using digital differential display, search on UniGene colon EST libraries and analysis of published data on colon cancer gene expression. A final list included the following genes: bone morphogenetic protein 4 (BMP4), cyclin D (CycD), family with sequence similarity 3, member D (FAM3D), gastrin (GAS), glycoprotein A33 transmembrane (GPA33), glutathione peroxidase 2 gastrointestinal (GPX2), galactoside-binding, soluble, 4 (galectin 4) (LGALS4), non-SMC, structural maintenance of chromosomes, element 1 protein (NSE1), tumor-associated calcium signal transducer 1 (TACSTD1), telomerase reverse transcriptase (hTERT), trefoil factor 3 intestinal (TFF3), transmembrane 4 superfamily member 3 (TM4SF3), UDP glycosyltransferase 1 family, polypeptide A9 (UGT1A9), villin 1 (VIL1), and the novel gene FLJ20127. The mRNA expression of these genes was evaluated in a pool of 16 samples from subjects diagnosed with colon cancer and from 16 normal-controls. We observed expression in 13 of the 15 investigated genes from the blood samples of the vast majority of patients considered, but also in a certain percentage of the controls (from 14.3 to 100%). This finding confirms that the extreme sensitivity of RT-PCR is able to detect minimal amounts of mRNA expressed in a non tissue-specific manner ('illegitimate transcription'). On the contrary, NSE1 and GAS mRNAs were not detected either in patient or in control blood samples; however, they were abundantly expressed in normal and cancerous colon mucosa, encouraging further search for useful markers able to detect epithelial cells in peripheral blood.

Aged↗
PubMed2003

Regulation of the innate and adaptive immune responses by Stat-3 signaling in tumor cells.

Although tumor progression involves processes such as tissue invasion that can activate inflammatory responses, the immune system largely ignores or tolerates disseminated cancers. The mechanisms that block initiation of immune responses during cancer development are poorly understood. We report here that constitutive activation of Stat-3, a common oncogenic signaling pathway, suppresses tumor expression of proinflammatory mediators. Blocking Stat-3 in tumor cells increases expression of proinflammatory cytokines and chemokines that activate innate immunity and dendritic cells, leading to tumor-specific T-cell responses. In addition, constitutive Stat-3 activity induces production of pleiotropic factors that inhibit dendritic cell functional maturation. Tumor-derived factors inhibit dendritic cell maturation through Stat-3 activation in progenitor cells. Thus, inhibition of antitumor immunity involves a cascade of Stat-3 activation propagating from tumor to dendritic cells. We propose that tumor Stat-3 activity can mediate immune evasion by blocking both the production and sensing of inflammatory signals by multiple components of the immune system.

Animals↗
PubMed2003

Geranylgeranyltransferase I inhibitor GGTI-2154 induces breast carcinoma apoptosis and tumor regression in H-Ras transgenic mice.

Treatment of H-Ras transgenic mice with the geranylgeranyltransferase I (GGTase I) inhibitor GGTI-2154 results not only in halting the growth of aggressive breast tumors but actually in inducing the regression (54 +/- 3%) of all 19 tumors analyzed. The farnesyltransferase (FTase) inhibitor FTI-2148 induced an average of 87 +/- 3% regression in the 13 tumors analyzed. GGTase I, but not FTase, is inhibited in breast tumors after treatment with GGTI-2154, whereas in tumors from mice treated with FTI-2148, only FTase is inhibited. The processing of the geranylgeranylated proteins RhoA, Rap1, and R-Ras, but not the farnesylated proteins H-Ras and HDJ-2, is inhibited in tumors obtained from mice treated with GGTI-2154. GGTI-2154 and FTI-2148 suppress constitutively activated phospho-Erk1/2 and phospho-Akt, induce apoptosis, and induce differentiation toward ductolobular breast epithelium. The data demonstrate that geranylgeranylated proteins are critical in H-Ras oncogenesis in vivo and give strong support for GGTase I as a target for anticancer drug discovery.

Alkyl and Aryl Transferases↗
PubMed2003

Insulin-like growth factor 1 receptor enhances invasion and induces resistance to apoptosis of colon cancer cells through the Akt/Bcl-x(L) pathway.

Colon cancer overexpresses insulin-like growth factor 1 (IGF1) and insulin-like growth factor 1 receptor (IGF1-R), as compared with normal or adenomatous mucosa, and it has been postulated that colorectal cancer cells depend on the IGF1/IGF1-R pathway for their growth and progression. In this study, using the human colon cancer cell line HCT116, we find that established HCT116/IGF1-R transfectants exhibit a more aggressive transformed phenotype than the parental cell line, as demonstrated by their higher proliferation rate in response to IGF1, higher degree of anchorage-independent growth, resistance to serum deprivation-induced apoptosis, and higher migratory capability in a monolayer "wounding assay." When injected into nude mice, HCT116/IGF1-R transfectants were highly invasive and produced distant metastases, whereas the parental cell did not. Moreover, the overexpression of IGF1-R in these cells was associated with IGF1-R-induced activation of Akt and up-regulation of the antiapoptotic protein Bcl-x(L). We also show that Akt pathway mediates IGF1-R-induced Bcl-x(L) expression at transcriptional level. Our data demonstrate, for the first time, that IGF1-R/Akt/Bcl-x(L) pathway may contribute to a more aggressive malignant phenotype, in a subset of colorectal cancers.

Animals↗
PubMed2003

Development of CD30+ lymphoproliferative disease in mice lacking interferon regulatory factor-1.

Human lymphomas continue to represent a major challenge in oncology, and in particular occur at very high frequencies in AIDS patients. We report here the development of a CD30+ lymphoproliferative disease in mice lacking the proapoptotic transcription factor, interferon regulatory factor-1. These mice most closely represent a model of human anaplastic large-cell lymphoma (ALCL). This mouse model of lymphoma will likely be useful in understanding the development of ALCL and in understanding the development of other closely related CD30+ forms of lymphoma, such as CD30+ Hodgkin's disease and CD30+ cutaneous T-cell lymphoma. This mouse model will also be useful in testing therapies for different forms of CD30+ lymphoma, in particular anti-CD30-based therapies.

Animals↗
PubMed2003

Regulation of caspase expression and apoptosis by adenomatous polyposis coli.

The adenomatous polyposis coli (APC) gene, a member of the WNT pathway, has been shown to assign intestinal epithelial cells to a program of proliferation or differentiation through regulation of the beta-catenin/TCF-4 complex. Wild-type APC, in certain cellular contexts, appears to induce differentiation and apoptosis, although mutant forms of APC, known to produce polyps and ultimately cancers, may suppress these events. Here, we show that mutant forms of APC can induce repression of select terminal caspases as a potential means of attenuating responses to apoptotic stimuli. Using gene expression profiling to interrogate the intact intestines of Apc(+/min) mice harboring numerous polyps, we identified a reduction in the mRNA expression of both caspases 3 and 7. We additionally identified a reduction in protein levels of caspase-3, caspase-7, and caspase-9 in human colon cancer specimens known to harbor APC mutations. A reduction in caspase protein levels resulted in resistance to apoptotic-inducing agents and restoration of caspase levels reinstated apoptotic capacities. Consistent with Wnt pathway involvement, dominant negative TCF/LEF induced caspase protein expression. These data provide support for the hypothesis that one of the functions of APC is the regulation of caspase activity and other apoptotic proteins by controlling their expression levels in the cell.

Adenomatous Polyposis Coli Protein↗
PubMed2003

p21Cip1 nullizygosity increases tumor metastasis in irradiated mice.

p21(Cip1) is a cyclin-dependent kinase inhibitor whose abundance increases in cells exposed to radiation or other DNA-damaging agents. Such increases activate a G1 checkpoint, which allows time for DNA repair before S phase entry. By inhibiting cell cycle progression, p21(Cip1) potentially suppresses tumorigenesis, and in support, we show that p21(Cip1) heterozygous and nullizygous mice develop more tumors than do wild-type mice when exposed to a single dose of gamma-irradiation. Importantly, we also show that p21(Cip1) nullizygosity increases the incidence of metastatic tumors in irradiated mice. We suggest that p21(Cip1) is haploinsufficient for tumor suppression and functions as an antimetastatic agent.

Animals↗
PubMed2003

AKT2 inhibition of cisplatin-induced JNK/p38 and Bax activation by phosphorylation of ASK1: implication of AKT2 in chemoresistance.

Cisplatin and its analogues have been widely used for treatment of human cancer. However, most patients eventually develop resistance to treatment through a mechanism that remains obscure. Previously, we found that AKT2 is frequently overexpressed and/or activated in human ovarian and breast cancers. Here we demonstrate that constitutively active AKT2 renders cisplatin-sensitive A2780S ovarian cancer cells resistant to cisplatin, whereas phosphatidylinositol 3-kinase inhibitor or dominant negative AKT2 sensitizes A2780S and cisplatin-resistant A2780CP cells to cisplatin-induced apoptosis through regulation of the ASK1/JNK/p38 pathway. AKT2 interacts with and phosphorylates ASK1 at Ser-83 resulting in inhibition of its kinase activity. Accordingly, activated AKT2 blocked signaling down-stream of ASK1, including activation of JNK and p38 and the conversion of Bax to its active conformation. Expression of nonphosphorylatable ASK1-S83A overrode the AKT2-inhibited JNK/p38 activity and Bax conformational changes, whereas phosphomimic ASK1-S83D inhibited the effects of cisplatin on JNK/p38 and Bax. Cisplatin-induced Bax conformation change was inhibited by inhibitors or dominant negative forms of JNK and p38. In conclusion, our data indicate that AKT2 inhibits cisplatin-induced JNK/p38 and Bax activation through phosphorylation of ASK1 and thus, plays an important role in chemoresistance. Further, regulation of the ASK1/JNK/p38/Bax pathway by AKT2 provides a new mechanism contributing to its antiapoptotic effects.

Apoptosis↗