Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cell Growth Processes”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources
PubMed2005

Osterix, a transcription factor for osteoblast differentiation, mediates antitumor activity in murine osteosarcoma.

Osterix is a novel zinc finger-containing transcription factor that is essential for osteoblast differentiation and bone formation. We hypothesized that osterix might have a role in osteosarcoma tumor growth and metastasis. Northern blot analysis showed that the mRNA level of osterix was decreased in two mouse osteosarcoma cell lines compared with its level in normal mouse osteoblasts. Osterix expression was also decreased in three human osteosarcoma cell lines. Transfection of the osx gene into the mouse osteosarcoma cells inhibited tumor cell growth in vitro and in vivo and significantly reduced tumor incidence, tumor volume, and lung metastasis following intratibial injection. Osterix expression was also associated with decreased osteolysis. Using an in vitro migration assay, osterix suppressed the migration of tumor cells to lung extracts. These results suggest that osterix expression may play a role in osteosarcoma tumor growth and metastasis.

Animals↗
PubMed2004

Analysis of gene expression patterns and chromosomal changes associated with aging.

Age is the largest single risk factor for the development of cancer in mammals. Age-associated chromosomal changes, such as aneuploidy and telomere erosion, may be vitally involved in the initial steps of tumorigenesis. However, changes in gene expression specific for increased aneuploidy with age have not yet been characterized. Here, we address these questions by using a panel of fibroblast cell lines and lymphocyte cultures from young and old age groups. Oligonucleotide microarrays were used to characterize the expression of 14,500 genes. We measured telomere length and analyzed chromosome copy number changes and structural rearrangements by multicolor interphase fluorescence in situ hybridization and 7-fluorochrome multiplex fluorescence in situ hybridization, and we tried to show a relationship between gene expression patterns and chromosomal changes. These analyses revealed a number of genes involved in both the cell cycle and proliferation that are differently expressed in aged cells. More importantly, our data show an association between age-related aneuploidy and the gene expression level of genes involved in centromere and kinetochore function and in the microtubule and spindle assembly apparatus. To verify that some of these genes may also be involved in tumorigenesis, we compared the expression of these genes in chromosomally stable microsatellite instability and chromosomally unstable chromosomal instability colorectal tumor cell lines. Three genes (Notch2, H2AFY2, and CDC5L) showed similar expression differences between microsatellite instability and chromosomal instability cell lines as observed between the young and old cell cultures suggesting that they may play a role in tumorigenesis.

Adult↗
PubMed2005

The role of hypoxia-inducible factor-1 in three-dimensional tumor growth, apoptosis, and regulation by the insulin-signaling pathway.

The purpose of this study was to establish the effect of hypoxia-inducible factor-1 (HIF-1) directly on tumor growth, independently of angiogenesis. This was done by growing wild-type mouse hepatoma cells (HEPA-1) and their HIF-1-deficient counterpart C4 as multicellular tumor spheroids and quantifying differences in growth rates and proliferative and apoptotic indices. Insulin and insulin-like growth factor-I are key growth factors, also able to regulate hypoxia-responsive genes via HIF-1; thus, the effects of insulin on this model were also investigated. Two-dimensional growth was serum dependent and no difference was seen between wild-type HEPA-1 and C4 cell growth profiles, but major differences were seen in three-dimensional growth. HIF-1 supported spheroid growth under hypoxia as the HEPA-1 spheroids grew faster than the C4. Surprisingly, the HIF-1-deficient cells had a higher proliferation rate in three-dimensional growth (C4 mean S-phase index, 13.6%; HEPA-1 mean S-phase index, 9%; P = 0.009) that was associated with an inhibition of apoptosis. However, the apoptosis rate was much greater in these spheroids (C4 mean apoptotic index, 6.4; HEPA-1 mean apoptotic index, 0.78%; P = 0.0006). Addition of insulin increased proliferation and apoptosis in both HEPA-1 and C4 spheroids, demonstrating an HIF-1-independent effect of insulin signaling in three-dimensional growth. These results indicate that the enhancing effect of HIF-1 in three-dimensional tumor growth is a balance of both reduced proliferation and enhanced survival, the latter being proportionally greater.

Animals↗
PubMed2005

The G protein-coupled receptor S1P2 regulates Rho/Rho kinase pathway to inhibit tumor cell migration.

Sphingosine 1-phosphate (S1P) is a lysophospholipid that exerts a variety of responses in cells such as proliferation, migration, and survival. These effects are mediated by G protein-coupled receptors on the cell surface (S1P1-5), which activate downstream signaling intermediates such as Rac and Rho GTPases. Mechanisms of S1P action in human glioblastoma cells are not well defined. S1P receptors (1-5) and S1P-metabolizing enzymes were expressed in three human glioblastoma cell lines. S1P had a profound and differential effect on glioblastoma cell migration. U87 cells treated with S1P showed a significant increase in migration, whereas U118 and U138 cell lines were strongly inhibited. S1P-mediated inhibition correlated with S1P2 receptor expression. FTY720-P, an S1P analogue that binds all S1P receptors except S1P2, did not inhibit glioblastoma cell migration. Overexpression of S1P2 further suppressed migration, and blockage of S1P2 mRNA expression by small interfering RNA reversed the inhibitory effect. Contrary to previous reports showing bimodal regulation of Rac activity and migration by S1P2 receptor stimulation, both Rac1 and RhoA GTPases were activated by S1P treatment in native cells and cells overexpressing S1P2. Treatment of U118 cells with the Rho-associated protein kinase (ROCK) inhibitor Y-27632 restored migration suggesting that ROCK-dependent mechanisms are important. Actin staining of S1P stimulated U118 cells overexpressing beta-galactosidase resulted in pronounced stress fiber formation that was exacerbated by S1P2 overexpression, partially blocked by S1P1, or totally abolished by pretreatment with Y-27632. These data provide evidence of a novel mechanism of S1P inhibition of tumor cell migration via Rho kinase-dependent pathway.

Amides↗
PubMed2005

Altered gene expression patterns in MCF-7 cells induced by the urban dust particulate complex mixture standard reference material 1649a.

Human exposures to polycyclic aromatic hydrocarbon (PAH) occur in complex mixtures. Here, gene expression patterns were investigated using standard reference material (SRM) 1649a (urban dust). MCF-7 cells were exposed to SRM 1649a alone or SRM 1649a with either benzo[a]pyrene (BP) or dibenzo[a,l]pyrene (DBP) for 24 hours. Global analyses of the gene expression data revealed alterations of 41 RNA transcripts with at least 2-fold change (signal log ratio </= -1 or >/= 1) in response to SRM 1649a exposure. Increase in expression of cytochrome P450 (CYP) genes was observed in response to BP exposure (CYP1A1 and CYP1B1; signal log ratio of 4.7 and 2.5, respectively). An additive induction of CYP1A1 and CYP1B1 was observed with cotreatment of SRM 1649a and BP. On the contrary, no change in gene expression of CYP1A1 and CYP1B1 was observed when the cells were exposed to DBP. Furthermore, to study the effect of complex PAH mixtures on the metabolic activation of carcinogenic PAH to DNA-binding derivatives and to relate this with gene expression studies, PAH-DNA adduct formation was determined. SRM 1649a decreased the total level of BP-DNA adducts in comparison with BP alone. No significant difference in adduct levels was observed in response to either DBP alone or in combination with SRM 1649a. These results provide a transcriptional signature for chemical carcinogen exposure; in addition, they suggest a major factor in carcinogenic activity of PAH within complex mixtures is their ability to promote or inhibit the activation of carcinogenic PAH by the induction of CYP enzymes.

Apoptosis↗
PubMed2004

Wnt3a growth factor induces androgen receptor-mediated transcription and enhances cell growth in human prostate cancer cells.

The Wnt signaling pathway plays a critical role in embryogenesis and tumorigenesis. However, biological roles of Wnt growth factors have not been fully characterized in prostate development and the pathogenesis of prostate cancer. In this study, we used Wnt3a-conditioned medium (Wnt3a-CM) and purified Wnt3a proteins to investigate whether there is a direct effect of Wnt3a on androgen receptor (AR)-mediated transcription and to determine its role in the growth of prostate cancer cells. We demonstrated that Wnt3a-CM either induces AR activity in the absence of androgens or enhances AR activity in the presence of low concentrations of androgens, whereas purified Wnt3a showed a pronounced effect in the presence of low concentrations of ligands. We also showed that Wnt3a-CM and the purified Wnt3a enhance the level of cytosolic and nuclear beta-catenin, suggesting an involvement of beta-catenin in this regulation. Moreover, treatment of LNCaP cells with Wnt3a-CM and purified Wnt3a significantly enhances cell growth in the absence of androgens. Our findings demonstrate that Wnt3a plays an important role in androgen-mediated transcription and cell growth. These results suggest a novel mechanism for the progression of prostate cancer.

Androgens↗
PubMed2005

Knockdown of STAT3 expression by RNA interference inhibits the induction of breast tumors in immunocompetent mice.

Constitutively activated STAT3 is involved in the formation of multiple types of tumors including breast cancer. We examined the effects of Stat3 protein knockdown by RNA interference using a dicistronic lentivirus small hairpin (shRNA) delivery system on the growth of mammary tumors in BALB/c mice induced by the 4T1 cell line. A single exposure of 4T1 cells to shRNA/STAT3 lentivirus transduced 75% of the cells with green fluorescent protein (GFP) within 96 hours. In cells selected for GFP expression, neither Stat3 protein nor phosphotyrosine Stat3 was detected. Tumor formation induced by injecting 4T1 cells into the mammary fat pad was blocked by expression of the shRNA for STAT3 whereas all mice injected with 4T1 cells expressing only GFP efficiently formed tumors. c-Myc expression was reduced 75% in cells expressing greatly reduced levels of Stat3 compared with the GFP control. Of interest, the level of activated Src, which is known to activate Stat3, was virtually eliminated but the level of the Src protein itself remained the same. Importantly, expression of Twist protein, a metastatic regulator, was eliminated in STAT3 knockdown cells. Invasion activity of STAT3 knockdown cells was strongly inhibited. However, the proliferation rate of cells in Stat3 knockdown cells was similar to that of the GFP control; the cell cycle was also not affected. We conclude from these studies that activated Stat3 protein plays a critical role in the induction of breast tumors induced by 4T1 cells by enhancing the expression of several important genes including c-Myc and the metastatic regulator Twist. These studies suggest that stable expression of small interfering RNA for STAT3 has potential as a therapeutic strategy for breast cancer.

Animals↗
PubMed2005

Proliferation of human neuroblastomas mediated by the epidermal growth factor receptor.

Neuroblastoma is a common solid tumor of childhood that is derived from the neural crest. Expression of epidermal growth factor (EGF) receptors (EGFRs) has been associated with enhanced cell growth and aggressive behavior in other tumors. Here, we examined the expression profile of EGFRs in neuroblastoma cell lines and primary tumors. We found that all 13 neuroblastoma cell lines examined expressed EGFR1 (HER1), most at readily detectable levels. Low levels of other human EGFR family receptors were also detected in almost all cell lines. All primary tumors examined expressed readily detectable levels of HER1 and HER3 and lower levels of HER2 and HER4. EGF had a significant effect on the proliferation of neuroblastoma cell lines in vitro. EGF treatment (100 ng/mL) of the cell lines SY5Y and NLF significantly increased cell number (P < 0.01). EGF stimulated more cells to enter S and G2-M phase, as suggested by flow cytometry, indicating that EGF increases cell number by increasing proliferation, with no appreciable change in apoptosis. EGF exposure resulted in receptor autophosphorylation and activation of both the mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/AKT pathways. Exposure to 0.5 micromol/L ZD1839, a HER1-specific inhibitor, caused a 40% to 50% reduction in the number of SY5Y and NLF cells grown in medium containing 10% fetal bovine serum (P < 0.01). Even at 0.01 micromol/L, ZD1839 inhibited autophosphorylation of HER1 by EGF. At 0.1 micromol/L, it also blocked phosphorylation of AKT, but not MAPK, in NLF cells. Additional studies showed that the PI3K/AKT-specific inhibitor LY294002 had a more profound effect than the MAPK-specific inhibitor U0126 in blocking EGF-induced cell proliferation. This suggests that the PI3K/AKT pathway is the main signaling pathway responsible for the proliferation effects of EGF in neuroblastomas. Our results also indicate that ZD1839 is a potent inhibitor of neuroblastoma cell proliferation; therefore, it may be a useful, biologically based therapeutic agent for these tumors.

Cell Growth Processes↗
PubMed2005

Phenoxodiol, a novel isoflavone, induces G1 arrest by specific loss in cyclin-dependent kinase 2 activity by p53-independent induction of p21WAF1/CIP1.

Phenoxodiol, an isoflavone derivative of genistein with unknown mechanism of action, is currently being evaluated in early human cancer clinical trials. To determine the mechanism of antiproliferative effects of phenoxodiol, we examined its effects in a battery of human cell lines. Although we observed caspase-dependent apoptosis in HN12 cells as early as 24 hours after exposure, clonogenic death occurred only after 48-hour exposure despite caspase blockade by the general caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (ZVAD)-fmk. Moreover, clear evidence of cell death as determined by nuclear morphology and plasmatic membrane damage occur despite ZVAD, suggesting that another mechanism besides caspase-dependent apoptosis is required for clonogenic death induced by phenoxodiol. In search for other potential antiproliferative effects, we assessed the effects of phenoxodiol in the cell cycle progression of human carcinoma cell lines. A significant G(1)-S arrest was observed by 12 hours of exposure in HN12 cell lines at concentrations > or =5 microg/mL. Cell cycle arrest occurred several hours (approximately 12 hours) before induction of apoptosis. Analysis of in vitro purified cyclin-dependent kinase (cdk) activity showed that phenoxodiol did not inhibit cdk activity. In contrast, cellular cdk2 activity obtained from HN12 cell lines exposed to phenoxodiol for 12 hours decreased by 60%, whereas cdk6 activity remained unaltered, suggesting that the loss of cdk2 activity was specific. Loss in cdk2 activity was preceded by the accumulation of the endogenous cdk inhibitor p21(WAF1). To assess the role of p21(WAF1) induction by phenoxodiol, we used HCT116 isogenic cell lines and showed that phenoxodiol induced G(1) arrest together with p21(WAF1) expression in wild-type clones. In contrast, p21(-/-) variants failed to show G(1) arrest. Finally, induction of p21 by phenoxodiol is p53 independent, as phenoxodiol induced p21 in HCT116 lacking p53. These data therefore indicate that phenoxodiol promotes G(1)-S arrest by the specific loss in cdk2 activity due to p53-independent p21(WAF1) induction. This novel feature of phenoxodiol may have clinical implications, as the majority of human malignancies have aberrations in cell cycle progression regulation.

Apoptosis↗
PubMed2005

Coadministration of histone deacetylase inhibitors and perifosine synergistically induces apoptosis in human leukemia cells through Akt and ERK1/2 inactivation and the generation of ceramide and reactive oxygen species.

Interactions between histone deacetylase inhibitors (HDACIs) and the alkyl-lysophospholipid perifosine were examined in human leukemia cells. Coadministration of sodium butyrate, suberoylanilide hydroxamic acid (SAHA), or trichostatin with perifosine synergistically induced mitochondrial dysfunction (cytochrome c and apoptosis-inducing factor release), caspase-3 and -8 activation, apoptosis, and a marked decrease in cell growth in U937 as well as HL-60 and Jurkat leukemia cells. These events were associated with inactivation of extracellular signal-regulated kinase (ERK) 1/2 and Akt, p46 c-jun-NH2-kinase (JNK) activation, and a pronounced increase in generation of ceramide and reactive oxygen species (ROS). They were also associated with up-regulation of Bak and a marked conformational change in Bax accompanied by membrane translocation. Ectopic expression of Bcl-2 delayed but was ultimately ineffective in preventing perifosine/HDACI-mediated apoptosis. Enforced expression of constitutively active mitogen-activated protein kinase kinase (MEK) 1 or myristoylated Akt blocked HDACI/perifosine-mediated ceramide production and cell death, suggesting that MEK/ERK and Akt inactivation play a primary role in these phenomena. However, inhibition of JNK activation (e.g., by the JNK inhibitor SP600125) did not attenuate sodium butyrate/perifosine-induced apoptosis. In addition, the free radical scavenger N-acetyl-L-cysteine attenuated ROS generation and apoptosis mediated by combined treatment. Finally, the acidic sphingomyelinase inhibitor desipramine attenuated HDACI/perifosine-mediated ceramide and ROS production as well as cell death. Together, these findings indicate that coadministration of HDACIs with perifosine in human leukemia cells leads to Akt and MEK/ERK disruption, a marked increase in ceramide and ROS production, and a striking increase in mitochondrial injury and apoptosis. They also raise the possibility that combining these agents may represent a novel antileukemic strategy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

Modulation of survival signaling pathways and persistence of the genotoxic stress as a basis for the synergistic interaction between the atypical retinoid ST1926 and the epidermal growth factor receptor inhibitor ZD1839.

Strategies targeting apoptotic pathways may have relevance to improve the efficacy of antitumor therapy. Because synthetic atypical retinoids are potent inducers of apoptosis, there is an increasing interest in exploiting their potential in novel therapeutic approaches. In the present study, we have investigated the cellular effects of the combination of a novel atypical retinoid, ST1926, and the epidermal growth factor receptor inhibitor ZD1839. The results indicated a synergistic interaction between the two drugs associated with a dramatic enhancement of apoptotic response, up-regulation of the cell death receptor DR5, and caspase 8 activation. Other molecular events induced by the cotreatment included (a) a stabilization of the ST1926-induced genotoxic stress detected by formation of phosphorylated gamma-H2AX foci and (b) a complete inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation associated with activation of the proapoptotic protein BAD (i.e., inhibition of phosphorylation on Ser112). In addition, ZD1839 itself inhibited survival pathways by causing a partial dephosphorylation of Akt and a marked down-regulation of survivin. The role of ERK-mediated survival pathways in the cellular response to the drug combination was further supported by the counteracting effect of stimulation of survival pathways by an alternative receptor tyrosine kinase and by the use of a specific inhibitor of the ERK pathway. In conclusion, the results support that the survival pathways activated by epidermal growth factor receptor are determinants of the cell susceptibility to ST1926-induced apoptosis and lowering survival signals may increase the cellular sensitivity to the atypical retinoid. The favorable pharmacologic profiles of both ST1926 and ZD1839 suggest that the combination of these well-tolerated agents may have therapeutic potential.

Adamantane↗
PubMed2004

The prosurvival activity of p53 protects cells from UV-induced apoptosis by inhibiting c-Jun NH2-terminal kinase activity and mitochondrial death signaling.

The cytoprotective function of p53 recently has been exploited as a therapeutic advantage for cancer prevention; agents activating the prosurvival activity of p53 are shown to prevent UV-induced damages. To explore the mechanisms of p53-mediated protection from UV-induced apoptosis, we have established stable clones of H1299 lung carcinoma cells expressing a temperature-sensitive p53 mutant, tsp53(V143A). At the permissive temperature of 32 degrees C, the tsp53(V143A)-expressing cells were arrested in G(1) phase without the occurrence of apoptosis; consistent with this is the preferential induction of genes related to growth arrest and DNA damage repair. Previous expression of functional tsp53(V143A) for > or =18 hours inhibited the release of proapoptotic molecules from mitochondria and protected the cells from UV-induced apoptosis; moreover, it suppressed the activation of c-Jun NH(2)-terminal kinase (JNK) signaling and relieved the effect of UV on p53 target gene activation. p53 associated with JNK and inhibited its kinase activity. Using the p53-null H1299 cells, we showed that inhibition of JNK blocked the UV-elicited mitochondrial death signaling and caspase activation. Our results suggest that the ability of p53 to bind and inactivate JNK, together with the activation of the p53 target genes related to cell cycle arrest and DNA damage repair, is responsible for its protection of cells against UV-induced apoptosis.

Apoptosis↗
PubMed2004

TRAIL inhibits tumor growth but is nontoxic to human hepatocytes in chimeric mice.

Tumor necrosis factor (TNF) family ligand TNF-alpha and Fas ligand (FasL) can trigger apoptosis in solid tumors, but their clinical usage has been limited by hepatotoxicity. TNF-related apoptosis-inducing ligand (TRAIL) is a newly identified member of the TNF family, and its clinical application currently is under a similar debate. Here, we report a recombinant soluble form of human TRAIL (114 to 281 amino acids) that induces apoptosis in tumor cells but not human hepatocytes. We first isolated human hepatocytes from patients and showed that the human hepatocytes expressed Fas but no TRAIL death receptor DR4 and little DR5 on the cell surface. Antibody cross-linked FasL, but not TRAIL, triggered apoptosis of the human hepatocytes through cleavage of caspases. We then examined TRAIL hepatotoxicity in severe combined immunodeficient/Alb-uPA chimeric mice harboring human hepatocytes. Intravenous injection of FasL, but not TRAIL, caused apoptotic death of human hepatocytes within the chimeric liver, thus killing the mice. Finally, we showed that repeated intraperitoneal injections of TRAIL inhibited intraperitoneal and subcutaneous tumor growth without inducing apoptosis in human hepatocytes in these chimeric mice. The results indicate that the recombinant soluble human TRAIL has a profound apoptotic effect on tumor cells but is nontoxic to human hepatocytes in vitro and in vivo.

Animals↗
PubMed2005

Additive antitumor effect of aromatase inhibitor letrozole and antiestrogen fulvestrant in a postmenopausal breast cancer model.

Blocking estrogen receptors with antiestrogens and blocking estrogen synthesis with aromatase inhibitors are two strategies currently being used for reducing the effect of estrogen in postmenopausal estrogen receptor-positive breast cancer patients. To optimize these treatment strategies, we have investigated whether tumor progression can be delayed by combining the pure antiestrogen fulvestrant with the nonsteroidal aromatase inhibitor letrozole. These studies were done in ovariectomized, athymic mice bearing tumors of estrogen receptor-positive human breast cancer cells stably transfected with the aromatase gene (MCF-7Ca). Groups of mice with equivalent tumor volumes were injected s.c. daily with vehicle (control; n = 6), fulvestrant (1 mg/d; n = 7), letrozole (10 microg/d; n = 18), or letrozole (10 microg/d) plus fulvestrant (1 mg/d; n = 5). All treatments were effective in suppressing tumor growth compared with controls (P < 0.001). Tumor volumes of the fulvestrant-treated group had doubled in 10 weeks. After 19 weeks of letrozole (10 microg/d) treatment when tumors had nearly doubled in volume, mice (n = 18) were assigned to second-line therapy with letrozole (100 microg/d; n = 6), tamoxifen (100 microg/d; n = 6), or remained on letrozole treatment (10 microg/d; n = 6). However, tumors continued to increase in volume in these groups. Tumors of animals treated with the combination of letrozole plus Faslodex regressed over 29 weeks of treatment by 45%. Thus, the combination of letrozole plus fulvestrant was more effective in suppressing tumor growth than either letrozole or fulvestrant alone or sequential therapies with tamoxifen or a higher dose of letrozole (100 microg/d).

Animals↗
PubMed2005

RASSF1A suppresses the c-Jun-NH2-kinase pathway and inhibits cell cycle progression.

Some oncogenes, such as activated Ras, cause the malignant transformation of lung cells. c-Jun-NH2-kinase (JNK) activation is essential for the oncogenic function of these cells. In this study, we show that RASSF1A inhibits the growth of lung cancer cells by blocking the JNK pathway. The exogenous expression of RASSF1A suppressed JNK phosphorylation, and cells stably transfected with RASSF1A showed reduced JNK and c-Jun phosphorylation and Cyclin D1 down-regulation. An in vitro kinase assay showed that the exogenous expression of RASSF1A inhibited JNK activity and that JNK activity suppression due to ectopically expressed RASSF1A was revived by RASSF1A siRNA treatment. Based on our data, we suggest that RASSF1A exerts a tumor-suppressing effect by blocking oncogene-mediated JNK activation in lung cells.

Azacitidine↗
PubMed2005

19-Nor-1,25(OH)2D2 (a novel, noncalcemic vitamin D analogue), combined with arsenic trioxide, has potent antitumor activity against myeloid leukemia.

Recently, we reported that a novel, noncalcemic vitamin D analogue (19-nor-1,25(OH)2D2; paricalcitol) had anticancer activity. In this study, we explored if paricalcitol enhanced anticancer effects of other clinically useful drugs in vitro against a large variety of cancer cells. Paricalcitol, when combined with As2O3, showed a markedly enhanced antiproliferative effect against acute myeloid leukemia (AML) cells. This combination induced monocytic differentiation of NB-4 acute promyelocytic leukemia (APL) cells and HL-60 AML cells and caused both to undergo apoptosis associated with down-regulation of Bcl-2 and Bcl-x(L). Paricalcitol induced monocytic differentiation of U937 AML cells, which was partially blocked by inducing expression of APL-related PML-retinoic acid receptor alpha (RARalpha) chimeric protein in the U937 cells containing a Zn2+-inducible expression vector coding for this fusion protein (PR9 cells). Exposure to As2O3 decreased levels of PML-RARalpha in PR9 cells, and the combination of paricalcitol and As2O3 enhanced their monocytic differentiation in parallel with the As2O3-mediated decrease of PML-RARalpha. Furthermore, As2O3 increased the transcriptional activity of paricalcitol probably by increasing intracellular levels of paricalcitol by decreasing the function of the mitochondrial enzyme 25-hydroxyvitamin D3-24-hydroxylase, which functions to metabolize the active vitamin D in cells. In summary, the combination of paricalcitol and As2O3 potently decreased growth and induced differentiation and apoptosis of AML cells. This probably occurred by As2O3 decreasing levels of both the repressive PML-RARalpha fusion protein and the vitamin D metabolizing protein, 25-hydroxyvitamin D3-24-hydroxylase, resulting in increased activity of paricalcitol. The combination of both of these Food and Drug Administration-approved drugs should be considered for treatment of all-trans retinoic acid-resistant APL patients as well as those with other types of AML.

Acute Disease↗
PubMed2005

HYAL1 hyaluronidase: a molecular determinant of bladder tumor growth and invasion.

Hyaluronic acid and HYAL1-type hyaluronidase show high accuracy in detecting bladder cancer and evaluating its grade, respectively. Hyaluronic acid promotes tumor progression; however, the functions of hyaluronidase in cancer are largely unknown. In this study, we stably transfected HT1376 bladder cancer cells with HYAL1-sense (HYAL1-S), HYAL1-antisense (HYAL1-AS), or vector cDNA constructs. Whereas HYAL1-S transfectants produced 3-fold more HYAL1 than vector transfectants, HYAL1-AS transfectants showed approximately 90% reduction in HYAL1 production. HYAL1-AS transfectants grew four times slower than vector and HYAL1-S transfectants and were blocked in the G2-M phase of the cell cycle. The expression of cdc25c and cyclin B1 and cdc2/p34-associated H1 histone kinase activity also decreased in HYAL1-AS transfectants. HYAL1-S transfectants were 30% to 44% more invasive, and HYAL1-AS transfectants were approximately 50% less invasive than the vector transfectants in vitro. In xenografts, there was a 4- to 5-fold delay in the generation of palpable HYAL1-AS tumors, and the weight of HYAL1-AS tumors was 9- to 17-fold less than vector and HYAL1-S tumors, respectively (P < 0.001). Whereas HYAL1-S and vector tumors infiltrated skeletal muscle and blood vessels, HYAL1-AS tumors resembled benign neoplasia. HYAL1-S and vector tumors expressed significantly higher amounts of HYAL1 (in tumor cells) and hyaluronic acid (in tumor-associated stroma) than HYAL1-AS tumors. Microvessel density in HYAL1-S tumors was 3.8- and 9.5-fold higher than that in vector and HYAL1-AS tumors, respectively. These results show that HYAL1 expression in bladder cancer cells regulates tumor growth and progression and therefore serves as a marker for high-grade bladder cancer.

Apoptosis↗
PubMed2005

Carcinoembryonic antigen-related cell adhesion molecule 1a-4L suppression of rat hepatocellular carcinomas.

Carcinoembryonic antigen (CEA)-related cell adhesion molecule 1 (CEACAM1) is a member of the CEA family of immunoglobulin-like adhesion molecules with two major splice variants, CEACAM1(a)-4L and CEACAM1(b)-4S, differing in the length of their COOH-terminal cytoplasmic tail. Both forms are down-regulated in prostate and liver carcinomas relative to normal tissues. We have previously shown in a nude mouse xenograft model that restoration of CEACAM1(a)-4L expression in human prostate carcinoma cells (PC-3) suppresses tumorigenicity, an effect observed with carcinomas from several other tissues but never established for hepatocellular carcinomas. In this report, we have examined the effect of CEACAM1(a)-4L on tumorigenicity of 1682A, a rat hepatocellular carcinoma that grows on the omentum when injected into the peritoneal cavity. Results show that restoration of CEACAM1(a)-4L expression at levels 13- and 0.45-fold compared with negative controls or normal hepatocytes, respectively, completely suppressed the formation of 1682A tumor nodules on the omentum at 3 weeks after injection. In contrast, 1682A cells infected with CEACAM1(b)-4S or an empty retroviral vector formed multiple clusters of tumor nodules. Although tumor nodules of 1682A cells positive and negative for CEACAM1(a)-4L did not display significant differences in histologic organization, aggregates formed in vitro by 1682A-L were smaller in size and displayed enlarged intercellular spaces relative to their 1682A-V counterparts. Restoration of CEACAM1(a)-4L expression did not elevate levels of apoptosis but seemed to cause an increase in the length of G1. This is the first demonstration of CEACAM1(a)-4L-induced tumor suppression in liver carcinomas using a quantifiable i.p. syngeneic transplantation model.

Animals↗