Biomedical subjects

Akira Horii

Publications and source records attributed to Akira Horii.

At least 37 records · Page 2Linked to original sources

PubMed2005

Computed tomographic images reflect the biologic behavior of small lung adenocarcinoma: they correlate with cell proliferation, microvascularization, cell adhesion, degradation of extracellular matrix, and K-ras mutation.

BACKGROUND: We previously reported that the computed tomographic M/L ratio (area of the tumor in the mediastinal computed tomographic image/area of the tumor in the lung computed tomographic image) of small peripheral lung adenocarcinoma is correlated with patient prognosis. METHODS: Immunostaining for p53, bcl-2, Ki-67, vascular endothelial growth factor, CD34, matrix metalloproteinase 2, matrix metalloproteinase 9, tissue inhibitor of matrix metalloproteinase 2, and mutation of K-ras was assessed in 131 surgically resected, primary peripheral lung adenocarcinomas of 30 mm or less in maximum diameter to clarify the relationship between computed tomographic findings and biologic activities. RESULTS: The numbers of patients with high labeling indexes of Ki-67 and high expression of vascular endothelial growth factor, CD34, matrix metalloproteinase 2, and matrix metalloproteinase 9 in the solid-type group (computed tomographic M/L ratio > or = 50%) were significantly higher than those in the faint density-type group (computed tomographic M/L ratio < 50%; P = .04 for Ki-67, P = .03 for vascular endothelial growth factor, P = .0009 for CD34, P = .001 for matrix metalloproteinase 2, and P = .00001 for matrix metalloproteinase 9). The number of patients with high levels of CD44v6 or tissue inhibitor of matrix metalloproteinase 2 staining in the faint density-type group was significantly higher than that in the solid-type group (P = .02 for CD44v6 and P = .01 for tissue inhibitor of matrix metalloproteinase 2). Independent variables capable of predicting computed tomographic M/L ratio included CD34, matrix metalloproteinase 2, matrix metalloproteinase 9, and tissue inhibitor of matrix metalloproteinase 2 (P = .0093, P = .0003, P = .0027, and P = .01, respectively; binary logistic regression analysis). CONCLUSIONS: Our results suggest that the computed tomographic image of small lung adenocarcinoma is correlated with biologic activities and thus provides possible prognostic information.

Adenocarcinoma↗

PubMed2005

Distinct progression pathways involving the dysfunction of DUSP6/MKP-3 in pancreatic intraepithelial neoplasia and intraductal papillary-mucinous neoplasms of the pancreas.

DUSP6/MKP-3 is identified as a candidate tumor suppressor gene for pancreatic cancer. The aim of this study was to elucidate the roles of DUSP6 in the pancreatic carcinogenesis through the pancreatic intraepithelial neoplasia and/or intraductal papillary-mucinous neoplasms, both of which are considered to be precursor lesions of invasive carcinoma of the pancreas, by comparing with involvements of other major tumor suppressive pathways. Expressions of DUSP6, CDKN2A, TP53, and SMAD4 were investigated by immunohistochemistry in a total of 206 lesions of dysplastic ductal precursors and carcinomas retrieved from 52 pancreata with invasive ductal carcinomas and 51 of those with intraductal papillary-mucinous neoplasms. The intensity of staining was evaluated in lesions at different atypical grades and statistically compared among them. Mutations of KRAS2 were analyzed by methods of the allele-specific oligonucleotide hybridization and nucleotide sequencing. In pancreata with invasive ductal carcinomas, expressions of DUSP6 were abrogated exclusively in the invasive carcinoma cells in contrast to its fairly preserved expressions in pancreatic intraepithelial neoplasia. In pancreata with intraductal papillary-mucinous neoplasms, abrogated expressions of DUSP6 were observed in a relatively small fraction of intraductal adenoma/borderlines and intraductal carcinomas. Most of the intraductal adenoma/borderline lesions with abrogation of DUSP6 harbored mutations of KRAS2. None of the molecules was associated with each other in any grade of lesions. Morphological variations of papillae of the intraductal papillary-mucinous neoplasms were evaluated and analyzed for their associations with abrogations of the molecules, which resulted in finding of no significant associations. Our results suggest that the abrogation of DUSP6 is associated exclusively with progression from pancreatic intraepithelial neoplasia to the invasive ductal carcinoma while it is potentially associated with initiation of intraductal papillary-mucinous neoplasms with mutated KRAS2, which is independent of other major tumor suppressive pathways in both types of neoplasms.

Adenocarcinoma, Mucinous↗

PubMed2005

The thymine DNA glycosylase MBD4 represses transcription and is associated with methylated p16(INK4a) and hMLH1 genes.

Epigenetic silencing through methyl-CpG (mCpG) is implicated in many biological patterns such as genome imprinting, X chromosome inactivation, and cancer development. In this process, the mCpG binding domain (MBD) proteins play an essential role in transmitting epigenetic information to downstream regulatory proteins. Among the five MBD proteins identified so far, MBD4 has been the only exception; it has long been thought to be a DNA repair protein. Herein we demonstrate that MBD4 has the ability to repress transcription through mCpG. Transcriptional repression by the MBD4 is histone deacetylase (HDAC) dependent, and MBD4 directly binds to Sin3A and HDAC1 at three central regions that overlap transcriptional repression domains. Furthermore, a chromatin immunoprecipitation assay clearly shows that MBD4 binds to hypermethylated promoters of the p16(INK4a) and hMLH1 genes. These results suggest that MBD4 is one of the essential components involved in epigenetic silencing in cancer and its repair activity is necessary for the maintenance of hypermethylated promoters.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Skin cooling alters the activation patterns of different heads of the quadriceps.

The purpose of this study was to examine the effect of selective skin cooling over m. vastus lateralis (VL) on the activation patterns of quadriceps femoris muscle during knee extension exercise (KEE) using muscle function magnetic resonance imaging (mfMRI). The isometric force production of the right thigh was tested in 7 healthy young men at maximum voluntary contraction (MVC), and the transverse relaxation time (T2) value was taken from mfMR images at rest and immediately after KEE with 4 sets of 10 repetitions at a load equal to 60% of their 10-rep maximum, with and without skin cooling. The cooling was carried out by ice pack on the surface of the skin of the VL for 3 min before resting mfMRI and MVC tests, and before KEE, during KEE, and during the KEE rest intervals. The percent change in T2 of the m. vastus intermedius was significantly increased by skin cooling in comparison to the change without skin cooling, p < 0.05. This result suggests that skin cooling alters the activation pattern of the different heads of the quadriceps.

Adult↗

PubMed2005

Exploration of genetic alterations in human endometrial cancer and melanoma: distinct tumorigenic pathways that share a frequent abnormal PI3K/AKT cascade.

Mutations of RAS, RAF, and PTEN, all important members of the RAS/MAPK and PI3K/AKT cascades, are reported in a variety of human tumors, including melanomas and endometrial cancer. In endometrial cancer, mutually exclusive mutations of PTEN and KRAS have been reported. On the other hand, mutation of BRAF is highly frequent, and mutually exclusive mutations of BRAF and NRAS have also been reported in melanomas. In this study, we elucidated the involvement of the up-regulation of RAS/MAPK and PI3K/AKT cascades in the pathogenesis of endometrial cancer and melanoma by analyzing the genes and molecules in these cascades. Twelve cell lines, six melanoma and six endometrial cancer, were analyzed; 4 (67%) of the 6 melanomas had gene mutations in the RAS/MAPK cascade, and a decrease or loss of PTEN expression was also observed. These results suggested that simultaneous up-regulations in these two cascades play important roles in carcinogenesis of melanocytes. However, no activation of AKT by phosphorylation was observed. On the other hand, 4 (67%) of the 6 endometrial cancer cell lines had mutually exclusive up-regulations in these cascades. However, two cell lines with up-regulation of the PI3K/AKT cascade also had up-regulation in the RAS/MAPK cascade induced by inactivation of DUSP6. These results suggest that simultaneous up-regulation of RAS/MAPK and PI3K/AKT cascades are crucial events in the pathogenesis of melanocytes, whereas up-regulation of either the RAS/MAPK or PI3K/AKT cascade is crucial for the majority of endometrial cancers.

Base Sequence↗

PubMed2004

Functional analysis of chromosome 18 in pancreatic cancer: strong evidence for new tumour suppressor genes.

BACKGROUND: In a previous work, we demonstrated that loss of heterozygosity of 18q is a frequent event significantly associated with poor prognosis in pancreatic cancer. We hypothesized that restoration of heterozygosity of chromosome 18 in pancreatic cancer cells would reduce their tumorigenicity. This study was intended to provide functional evidence for the existence of new tumour suppressor gene(s) located on chromosome 18. METHOD: Restoration of heterozygosity was achieved by introducing a normal copy of chromosome 18 into pancreatic ductal carcinoma using a microcell-mediated chromosome transfer technique. The tumorigenicity and metastatic ability of both the parental cells and resulting hybrids were assessed in vitro and in vivo. RESULTS: In vitro growth of hybrid clones was significantly delayed compared to parental cells. This was paralleled by a significantly lower rate of promoting invasive carcinoma in nude mice and a longer latency with hybrid cells compared with parental tumour cells. Hybrid clones showed significant suppression in the number of surface lung metastases when compared with parental cells. CONCLUSION: These data represent strong functional evidence that chromosome 18q encodes strong tumour and metastasis suppressor activity that is able to switch human pancreatic cancer cells to a dormant phenotype.

Animals↗

PubMed2004

Chromosome 12, frequently deleted in human pancreatic cancer, may encode a tumor-suppressor gene that suppresses angiogenesis.

Several lines of evidence have suggested that the long arm of chromosome 12 may carry a tumor-suppressor gene(s) that plays a role in pancreatic ductal carcinogenesis. We have previously found a significant association between loss of heterozygosity of the 12q arm and a poor prognosis in pancreatic cancer patients. In this study, we introduced a normal copy of chromosome 12 into some pancreatic ductal carcinoma cells. Both anchorage-dependent and -independent proliferations as well as invasiveness were similar throughout the hybrid clones when compared with their corresponding parental cells. In sharp contrast, significant suppression of tumorigenesis was observed after inoculation of the hybrid clones into nude mice. Measurements made up to 1 month later showed that there was a significant delay in the growth of tumors into which the introduced normal copy of chromosome 12 had been restored. More significantly, using our dorsal skin chamber and an intravital microscopy system experiment in SCID mice, we demonstrated and visualized directly that implantation of the hybrids failed to promote the angiogenic phenotype encountered in the parental cells. Gene expression profiling using the complementary DNA microarray system identified a set of 24 genes differentially expressed between the hybrids and parental cells. An additional set of 18 genes was also identified that were differentially expressed between the hybrid clone that lost its growth-suppression activity and one that retained such activity. Another set of 25 genes mapped on 12q was detected that showed high expression levels in the hybrid clones retaining growth-suppressive activity. In summary, this study provides the first functional evidence of the existence of an additional tumor-suppressor gene(s) on chromosome 12, whose absence is responsible for the pathogenesis in pancreatic ductal carcinogenesis.

Animals↗

PubMed2004

Molecular pathology of pancreatic cancer: in quest of tumor suppressor genes.

To find molecular clues useful for early detection and effective therapy for pancreatic cancer, we first carried out genomic analysis by means of comparative genomic hybridization and micro-satellite analysis. We found very complicated molecular alterations in multiple chromosomal regions, including 1p, 6q, 9p, 12q, 17p, 18q, and 21q for losses and 8q and 20q for gains. These diverse changes are very characteristic of pancreatic cancer, and from this information, we developed a method for detecting the aberrant copy numbers of specific chromosomal regions by fluorescence in situ hybridization in cells collected from pancreatic juice for early diagnosis of pancreatic neoplasms. The regions of losses suggest the existence of tumor suppressor genes (TSGs). We identified DUSP6/MKP-3 at 12q21-q22 as a strong candidate TSG; it showed epigenetic inactivation in some fractions of invasive pancreatic cancer and growth suppression and apoptosis by overexpression in vitro. To determine the pathologic roles of 18q, we introduced a normal copy of chromosome 18 into cultured pancreatic cancer cells. The introduction induced marked suppressions of tumor formation and metastasis formation in vivo. We continue work to more completely understand the complex molecular mechanisms of pancreatic carcinogenesis and to apply the information gained to the clinical treatment of pancreatic cancer.

Chromosome Aberrations↗

PubMed2004

The role of chromosome 18 abnormalities in the progression of pancreatic adenocarcinoma.

To date, the events that mediate tumor progression in pancreatic cancer are still poorly understood. Cytogenetic, allelotype, and somatic cell hybrid studies in human pancreatic adenocarcinoma have suggested that chromosome 18 may carry tumor suppressor genes (TSGs), including SMAD4. We previously identified that LOH of 18q at the SMAD4 locus, along with LOHs on 17p and 12q, positively associated with poor prognoses of pancreatic cancer patients. However, restoration of the SMAD4 gene did not suppress in vitro proliferation of pancreatic cancer cells that harbored homozygous deletion of this gene. An intraductal papillary mucinous neoplasm (IPMN ) is thought to be one of the premalignant lesions of the pancreas that progresses to carcinoma. Although there were frequent LOH (7/14, 50%) at the SMAD4 locus in IPMN samples, SMAD4 protein was observed immunohistochemically in tumor cells, and no mutations of the SMAD4 gene were observed, suggesting that it is the existence of a TSG in 18q, other than SMAD4, that suppresses cell growth. To functionally assess the activity of chromosome 18 in pancreatic cancer, we transferred a normal copy of the chromosome into pancreatic ductal carcinoma cells with and without completely inactivated SMAD4. In this study, in vitro growth of the hybrid cells was significantly suppressed compared with the parental cells, regardless of the initial SMAD4 status. To estimate the metastatic ability of the hybrids, we used a lung colonization model. At the end of the experiment, there was significant suppression of the number of surface metastases developing in mice injected with hybrids in comparison with those injected with parental cells. To identify and characterize genes that are involved in the progression of pancreatic cancer, we used micro-array expression analysis employing a 20k oligo-array system. It was revealed that there was increased expression of 4 genes relating to apoptosis in the 18 chromosome hybrids cells compared with the parental cells. We are now analyzing the function of these genes.

Animals↗

PubMed2004

BRAF point mutations in primary melanoma show different prevalences by subtype.

To elucidate the biological significance of activating mutations of BRAF in human malignant tumors, we performed a mutation analysis using 43 cell lines established from tumors that had developed in several kinds of human organs. Because the same V599E point mutation was observed in three of six melanoma cell lines and no such mutations were observed in other types of cancers, we focused further on melanoma, performed mutation analyses of NRAS, KRAS, CTNNB1, and p16/p14(ARF) in these cell lines, and found one NRAS mutation and three p16/p14(ARF) mutations. We further searched for mutations of BRAF and NRAS in 35 primary sporadic melanomas from 35 Japanese patients and detected the V599E BRAF point mutation in only nine (26%) of them. Significant differences in mutation frequency were observed among four histological subtypes; four (50%) of eight superficially spreading melanoma and five (33%) of 15 acral lentiginous melanoma had the mutation, whereas none of 12 other types (six nodular melanoma, five lentigo melanoma, and one mucosal melanoma) had it. The BRAF mutation was observed frequently even in small lesions, indicating that activation of this gene may be one of the early events in the pathogenesis of some melanomas.

Base Sequence↗

PubMed2004

A new assay using surface plasmon resonance (SPR) to determine binding of the Lactobacillus acidophilus group to human colonic mucin.

A new binding assay to investigate the mechanism of adhesion of lactic acid bacteria to the human intestine was established by the surface plasmon resonance technique using a biosensor BIACORE1000. Cells of 26 strains of the Lactobacillus acidophilus group as analytes were eluted onto a sensor chip on which were immobilized biotinylated A-trisaccharide polymer probes having human A-type antigen [(GalNAcalpha1-3(Fucalpha1-2)Gal)-] or human colonic mucin of blood type A (HCM-A) as ligands. In the first screening, high adhesive affinity to the A-trisaccharide BP-probe was observed in L. acidophilus OLL2769, L. crispatus JCM8778, LA205 and LA206. In the second screening, which used HCM-A, only L. acidophilus OLL2769 and L. crispatus JCM8778 were selected as adhesive strains with specific binding ability to human A-antigen. The results indicated that some strains of the L. acidophilus group could recognize and bind the sugar chain of A-antigen structure on HCM.

Bacterial Adhesion↗

PubMed2004

DSCP1, a novel TP53-inducible gene, is upregulated by strong genotoxic stresses and its overexpression inhibits tumor cell growth in vitro.

TP53-inducible genes play crucial roles from many biological aspects including cell cycle control, DNA repair, and apoptosis. Herein we report the identification and characterization of a novel TP53-inducible gene, DSCP1 (damage stimulated cytoplasmic protein 1), localized at 17q11. The gene was expressed ubiquitously in normal adult tissues; its protein product was localized mainly in the cytoplasm with anchoring on unknown subcellular structures. Exogenous expression of TP53 induced expression of DSCP1, but more interestingly, DSCP1 was induced by strong genotoxic stresses not only in TP53-maintaining cells but also in TP53-dysfunctioning cells, although the induction was much more efficient in the former than in the latter. In cultured cancer cells, the basal expression level appeared to depend on the functional status of TP53. Moreover, exogenous overexpression of DSCP1 retarded cancer cell growth in vitro. These results indicate that DSCP1 is a stress-inducible gene in both a TP53 dependent and independent manner and that its protein product can inhibit cancer cell growth.

Amino Acid Sequence↗

PubMed2004

Screening for functional tumor suppressor activity in pancreatic cancer.

Pancreatic cancer has a well-known reputation as one of the leading causes of cancer deaths worldwide. Thus, acquisition of efficient approaches and markers for accurate detection at the earlier stages of the disease should be prioritized. We have been focusing on tumor suppressor genes (TSGs) activity in pancreatic cancer to find effective methods for its genetic diagnosis and/or treatment. In this study, we utilized the technique of micro-cell-mediated chromosome transfer (MMCT) to introduce a normal copy of human chromosome 18 individually into some pancreatic cancer cells. Subsequently, the tumorigenic ability of the resulting hybrids was assessed in vitro and in vivo. In vitro growth of the hybrid clones was significantly delayed as compared to the parental cells. This was paralleled by the hybrid cells promotion of invasive carcinomas in nude mice at a significantly lower rate and with a longer latency than the parental tumor cells. This study provides evidence that MMCT is an efficient tool for screening of tumor suppressor activity in pancreatic cancer. The functional data emerging from this study bring into sharp relief the implication of chromosome 18 as a putative location for new TSG(s), yet to be identified in this region.

Animals↗

PubMed2004

Infrequent somatic mutations of the ICAT gene in various human cancers with frequent 1p-LOH and/or abnormal nuclear accumulation of beta-catenin.

Abnormal nuclear accumulation of beta-catenin (CTNNB1) plays one of the key roles in the upregulation of the Wnt signalling pathway that can cause acceleration of cell proliferation. ICAT, inhibitor of beta-catenin and TCF4/beta-catenin-interacting protein, was isolated and mapped to 1p36, a frequent target for LOH in many human cancers. We have previously observed that a number of tumors showing abnormal accumulation of the CTNNB1 protein do not harbor a mutation of the CTNNB1 gene. We studied the precise localization and genomic structure of the ICAT gene and analyzed its mutations in 178 human tumors developed in organs with frequent nuclear accumulation of the CTNNB1 protein and/or frequent LOHs of 1p36, but no genetic alterations were observed. Our results imply that i) genetic alteration of the ICAT gene does not play an important role in abnormal accumulation of CTNNB1 that would cause up-regulation of the Wnt signalling pathway, ii) mechanisms other than genetic alteration may have inactivated ICAT function, or iii) gene(s) on 1p36 other than ICAT may be the responsible tumor suppressor gene for tumors that show frequent 1p36-LOH.

Adaptor Proteins, Signal Transducing↗

PubMed2004

TU12B1-TY, a novel gene in the region at 12q22-q23.1 frequently deleted in pancreatic cancer, shows reduced expression in pancreatic cancer cells.

Loss of heterozygosity (LOH) on 12q is frequently observed in primary pancreatic cancer, as well as in cancers of other tissues such as stomach and germ cells. LOH correlates with poor prognosis in patients suffering from pancreatic cancer. In quest of tumor suppressor genes in this region, we used bacterial artificial chromosome (BAC) clones to construct a contig to cover one of the two targeted regions previously detected in pancreatic cancer; this region, 12B, is no larger than 650-kb between D12S360 and D12S78 at 12q22-q23.1. While constructing a detailed physical map and placing expressed sequence-tags, we identified a novel human gene, TU12B1-TY. This gene consisted of at least 14 exons and harbored an open reading frame possibly encoding a 473 amino-acid protein. A motif prediction program revealed a transmembrane domain in its carboxyl terminus. Expression in human tissues was found in the brain, placenta, skeletal muscle, pancreas, testis, uterus, and small intestine. In 21 pancreatic cancer cell lines analyzed, we found no structural alteration but all of them showed reduced expression. The present results indicate that reduced function of TU12B1-TY may contribute to the development and/or progression of human pancreatic cancer.

Blotting, Northern↗

PubMed2003

Inserting chromosome 18 into pancreatic cancer cells switches them to a dormant metastatic phenotype.

We demonstrated previously that restoration of chromosome 18 suppressed growth of pancreatic cancer cells in vitro, as well as that of tumors inoculated into nude mice. We also demonstrated that loss of 18q was associated with poor prognosis. Hence there is the possibility that the 18q arm harbors a gene(s) implicated in tumor progression and/or metastasis. In this study, we evaluated the effect of restoring chromosome 18 on metastasis in a few human pancreatic cancer cell lines with and without inactivation of SMAD4. After microcell-mediated chromosome 18 transfer, hybrid cells showed more than a 10-fold weaker metastatic ability than corresponding parental cells; mice injected with 1.25 x 10(6)/250 micro l hybrid clones via tail vein had less than one-tenth of the number of macroscopic metastases in the lung when compared with the control cells. Microscopic examination confirmed the decrease in the number of metastatic lesions. After inoculation of hybrid cells, more than 80% of the high-power fields showed no micrometastases, contrasting with their abundance after using the parental cells. Hybrid cells restored maspin expression irrespective of SMAD4 status in corresponding parental cells. On the other hand, significantly lower vascular endothelial growth factor and matrix metalloproteinase 2 secretion was observed by measuring levels in the conditioned media (CM); the averages were 22% and 20%, respectively. Angiogenesis assays using in vivo Matrigel plugs demonstrated that less neovascularization was observed in nude mice with hybrid cells than with corresponding parental cells. When cells were treated with CM from hybrids, the migration of human umbilical vascular endothelial cells was decreased, but it was partially restored with anti-vascular endothelial growth factor neutralizing antibody, as compared with CM from parental cells. These data represent the first functional evidence suggesting that chromosome 18q encodes a gene that strongly suppresses metastatic activity, possibly through dormancy.

Animals↗

PubMed2003

Restoration of SMAD4 by gene therapy reverses the invasive phenotype in pancreatic adenocarcinoma cells.

SMAD4 is a critical cofactor in signal transduction pathways activated in response to transforming growth factor-beta (TGF-beta)-related ligands, regulating cell growth and differentiation. The roles played by SMAD4 inactivation in tumours highlighted it as a tumour-suppressor gene. However, restoration of the TGF-beta antiproliferative pathway following SMAD4 gene transfer in null-tumour cell lines is controversial. Herein, we report the inhibitory effects of SMAD4 on pancreatic tumour invasion and angiogenesis. Adenoviral transfer of this gene in a panel of SMAD4 homozygous-deleted human pancreatic tumour cell lines restored SMAD4 protein expression and function. Although it did not affect proliferation significantly in vitro, SMAD4 inhibited in vivo tumour growth in immunodeficient mice. In this xenograft setting, differential suppression of tumour growth in vivo was mediated, at least in part, through downregulation of vascular endothelial growth factor and expression of gelatinases. We documented the reduced invasion and angiogenesis histologically and by intravital microscopy, and gained mechanistic insight at the messenger and protein level. Finally, we found a negative reciprocal regulation between SMAD4 and ETS-1. ETS-1 is considered a marker for tumour invasion. Upon SMAD4 deletion, we detected high expression levels of ETS-1 in pancreatic tumour cells, suggesting the shift of the pancreatic tumour toward an invasive phenotype.

Adenocarcinoma↗

PubMed2003

APAF-1-ALT, a novel alternative splicing form of APAF-1, potentially causes impeded ability of undergoing DNA damage-induced apoptosis in the LNCaP human prostate cancer cell line.

We have found a novel alternative splicing product of the apoptotic protease activating factor 1 (APAF-1), termed APAF-1-ALT, in the LNCaP human prostate cancer cell line. APAF-1-ALT harbors the caspase recruitment domain and an incomplete CED-4 like/ATPase domain, but lacks the WD-40 repeat units. The LNCaP cell expressed the full-length APAF-1 weakly and APAF-1-ALT rather abundantly, especially after mycoplasma infection. LNCaP underwent a retarded DNA damage-induced apoptosis, which was independent of caspase 9 activity. APAF-1-ALT functioned less effectively in inducing apoptosis than did APAF-1-XL, the full-length APAF-1, in transient transfection. Moreover, APAF-1-ALT interfered with APAF-1-XL's ability to induce apoptosis in transient double transfection experiment. These results indicate that APAF-1-ALT is a molecule that is deficient and impeded for mediating apoptosis and that it may contribute to the resistance to DNA damage-induced treatment observed in LNCaP.

Actins↗