Detection and quantitation of mutant K-ras codon 12 restriction fragments by capillary electrophoresis

Anti-colorectal cancer effects of anti-p21Ras scFv delivered by the recombinant adenovirus KGHV500 and cytokine-induced killer cells

BACKGROUND

Colorectal cancer (CRC) is the most common type of gastrointestinal cancer. CRC gene therapy mediated by adenovirus holds great promise for the treatment of malignancies. However, intravenous delivery of adenovirus exhibits limited anti-tumor activity in vivo when used alone.

METHODS

In this study, the antitumor activity of the recombinant adenovirus KGHV500 was assessed with the MTT, TUNEL, Matrigel invasion and cell migration assays. To enhance the intravenous delivery of KGHV500 in vivo, cytokine-induced killer (CIK) cells were used as a second vector to carry KGHV500. We explored whether CIK cells could carry the recombinant adenovirus KGHV500 containing the anti-p21Ras single chain fragment variable antibody (scFv) gene into tumors and enhance antitumor potency.

RESULTS

Our results showed that KGHV500 exhibited significant antitumor activity in vitro. In the nude mouse SW480 tumor xenograft model, the combination of CIK cells with KGHV500 could induce higher antitumor activity against colorectal cancer in vivo than that induced by either CIK or KGHV500 alone. After seven days of treatment, adenovirus and scFv were detected in tumor tissue but were not detected in normal tissues by immunohistochemistry. Therefore, KGHV500 replicates in tumors and successfully expresses anti-p21Ras scFv in a colorectal cancer xenograft model.

CONCLUSIONS

Our study provides a novel strategy for the treatment of colorectal cancer by combining CIK cells with the recombinant adenovirus KGHV500 which carried anti-p21 Ras scFv.

p190A RhoGAP is involved in EGFR pathways and promotes proliferation, invasion and migration in lung adenocarcinoma cells

Overcoming acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR‑TKIs) is an emerging issue in lung cancer treatment. We report evidence that a GTPase-activating protein, p190-A RhoGAP (p190), is a potential molecular target for the treatment of lung adenocarcinoma. We documented inhibition of phosphorylation of p190 by EGFR-TKI treatment in lung adenocarcinoma cell lines. Small interfering RNA-mediated knockdown of p190 leads lung adenocarcinoma cells to growth suppression and to inhibition of invasion/migration through inducing cell cycle arrest but not apoptosis. These findings were observed not only in EGFR-TKI-sensitive cells but also in EGFR-TKI-resistant cells; even in cell lines harboring K-ras mutations. The mechanism of this inhibitory effect on growth and invasion/migration was Ras inactivation through disrupting the p190-A RhoGAP/p120RasGAP complex. In addition, a high level of p190 mRNA expression was observed in majority of surgically obtained tissue from lung adenocarcinoma patients. Overexpression of p190 mRNA associated with poor disease-free survival. The results suggest that overexpression of p190 mRNA may be involved in the carcinogenesis of lung adenocarcinoma. These findings indicate that p190 is a possible molecular target for treatment of lung adenocarcinoma.

Differential response to 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3) in non-small cell lung cancer cells with distinct oncogene mutations

We previously demonstrated that non-small cell lung cancer (NSCLC) cells and primary human lung tumors aberrantly express the vitamin D3-catabolizing enzyme, CYP24, and that CYP24 restricts transcriptional regulation and growth control by 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) in NSCLC cells. To ascertain the basis for CYP24 dysregulation, we assembled a panel of cell lines that represent distinct molecular classes of lung cancer: cell lines were selected which harbored mutually exclusive mutations in either the K-ras or the Epidermal Growth Factor Receptor (EGFR) genes. We observed that K-ras mutant lines displayed a basal vitamin D receptor (VDR)(low)CYP24(high) phenotype, whereas EGFR mutant lines had a VDR(high)CYP24(low) phenotype. A mutation-associated difference in CYP24 expression was also observed in clinical specimens. Specifically, K-ras mutation was associated with a median 4.2-fold increase in CYP24 mRNA expression (p=4.8×10(-7)) compared to EGFR mutation in a series of 147 primary lung adenocarcinoma cases. Because of their differential basal expression of VDR and CYP24, we hypothesized that NSCLC cells with an EGFR mutation would be more responsive to 1,25(OH)2D3 treatment than those with a K-ras mutation. To test this, we measured the ability of 1,25(OH)2D3 to increase reporter gene activity, induce transcription of endogenous target genes, and suppress colony formation. In each assay, the extent of 1,25(OH)2D3 response was greater in EGFR mutation-positive HCC827 and H1975 cells than in K-ras mutation-positive A549 and 128.88T cells. We subsequently examined the effect of combining 1,25(OH)2D3 with erlotinib, which is used clinically in the treatment of EGFR mutation-positive NSCLC. 1,25(OH)2D3/erlotinib combination resulted in significantly greater growth inhibition than either single agent in both the erlotinib-sensitive HCC827 cell line and the erlotinib-resistant H1975 cell line. These data are the first to suggest that EGFR mutations may identify a lung cancer subset which remains responsive to and is likely to benefit from 1,25(OH)2D3 administration. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

Epithelial-mesenchymal transition stimulates human cancer cells to extend microtubule-based invasive protrusions and suppresses cell growth in collagen gel

Epithelial-mesenchymal transition (EMT) is a crucial event in tumor invasion and metastasis. However, most of past EMT studies have been conducted in the conventional two-dimensional (2D) monolayer culture. Therefore, it remains unclear what invasive phenotypes are acquired by EMT-induced cancer cells. To address this point, we attempted to characterize EMT cells in more physiological, three-dimensional (3D) collagen gel culture. EMT was induced by treating three human carcinoma cell lines (A549, Panc-1 and MKN-1) with TGF-ß. The TGF-ß treatment stimulated these cells to overexpress the invasion markers laminin γ2 and MT1-MMP in 2D culture, in addition to the induction of well-known morphological change and EMT marker expression. EMT induction enhanced cell motility and adhesiveness to fibronectin and collagen in 2D culture. Although EMT cells showed comparable cell growth to control cells in 2D culture, their growth rates were extremely suppressed in soft agar and collagen gel cultures. Most characteristically, EMT-induced cancer cells commonly and markedly extended invasive protrusions in collagen gel. These protrusions were mainly supported by microtubules rather than actin cytoskeleton. Snail-introduced, stable EMT cells showed similar protrusions in 3D conditions without TGF-ß. Moreover, these protrusions were suppressed by colchicine or inhibitors of heat shock protein 90 (HSP-90) and protein phosphatase 2A. However, MMP inhibitors did not suppress the protrusion formation. These data suggest that EMT enhances tumor cell infiltration into interstitial stroma by extending microtubule-based protrusions and suppressing cell growth. The elevated cell adhesion to fibronectin and collagen and high cell motility also seem important for the tumor invasion.

Molecular mechanisms for the regulation of Nrf2-mediated cell proliferation in non-small-cell lung cancers

We previously demonstrated that the transcription factor NF-E2-related factor2 (Nrf2), expressed abundantly in non-small-cell lung cancer (NSCLC) cells, plays a pivotal role in the proliferation and chemoresistance of NSCLC. Here we show that Nrf2-mediated NSCLC cell proliferation is dually regulated by epidermal growth factor receptor (EGFR) signaling and an Nrf2 repressor protein Keap1 (Kelch-like ECH-associated protein-1). NSCLC cells expressing wild-type EGFR and Keap1 genes show enhanced proliferation on stimulation with EGFR ligand under non-stress conditions. Exposure to cigarette smoke extract (CSE) enhanced cell proliferation by modification of the Nrf2/Keap1 interaction. Although EGFR-tyrosine kinase inhibitor (TKI) inhibited the proliferation of these cells, exposure to CSE attenuated its efficacy. In NSCLC cells with Keap1 gene mutations, Nrf2 was constitutively activated owing to dysfunction of Keap1 and cells proliferated independently of EGFR signaling. Furthermore, EGFR-TKI was unable to inhibit their proliferation. In NSCLC cells with EGFR gene mutations, Nrf2 was constitutively activated by EGFR signaling. In these cells, proliferation was largely dependent on the EGFR signaling pathway. Although these cells were highly sensitive to EGFR-TKI, exposure to CSE or knockdown of Keap1 mRNA reduced sensitivity to EGFR-TKI. We found a case of NSCLC showing resistance to EGFR-TKI despite having EGFR-TKI-sensitive EGFR gene mutation because of dysfunctional mutation in Keap1 gene. Results indicate that oxidative stress reduces the anticancer effects of EGFR-TKI in wild-type Keap1 NSCLC cells. Analysis of Keap1 dysfunction may become a novel molecular marker to predict resistance to EGFR-TKI in NSCLC cells having EGFR-TKI-sensitive EGFR mutations. Finally, as the downstream molecule of both EGFR and Keap1 signaling, Nrf2 is an important molecular target for the treatment of NSCLC, where cells have mutations in EGFR, KRAS or Keap1 genes.

Anti-tumor effect in human lung cancer by a combination treatment of novel histone deacetylase inhibitors: SL142 or SL325 and retinoic acids

Histone deacetylase (HDAC) inhibitors arrest cancer cell growth and cause apoptosis with low toxicity thereby constituting a promising treatment for cancer. In this study, we investigated the anti-tumor activity in lung cancer cells of the novel cyclic amide-bearing hydroxamic acid based HDAC inhibitors SL142 and SL325. In A549 and H441 lung cancer cells both SL142 and SL325 induced more cell growth inhibition and cell death than the hydroxamic acid-based HDAC inhibitor suberoylanilide hydroxamic acid (SAHA). Moreover, the combination treatment using retinoid drugs ATRA or 9-cis RA along with SL142 or SL325 significantly induced more apoptosis and suppressed colony formation than the single use of either. The expression of the retinoic acid receptors RARα, RARβ, RXRα and RXRβ were unchanged with the treatment. However a luciferase reporter construct (pGL4. RARE 7x) containing seven tandem repeats of the retinoic acid responsible element (RARE) generated significant transcriptional activity after the combination treatment of retinoic acids and SL142 or SL325 in H441 lung cancer cells. Moreover, apoptosis-promoting Bax expression and caspase-3 activity was increased after the combination treatment. These results suggest that the combination treatment of SL142 or SL325 with retinoic acids exerts significant anti-tumor activity and is a promising therapeutic candidate to treat human lung cancer.

The role of K-ras gene mutation in TRAIL-induced apoptosis in pancreatic and lung cancer cell lines

PURPOSE

Pancreatic ductal and lung adenocarcinomas are the most common and prevalent types of human neoplasms with a greater than 80% mortality rate. The poor prognosis of both these cancers are likely due to the absence of valid approaches for early detection, the frequency of its metastases at the time of diagnosis, frequent recurrence after surgery, and poor responsiveness to chemotherapy. Most notably, the early development of pancreatic intraepithelial neoplasia and lung lesions is suggested to be the result of a mutation in the K-ras (G12D) oncogene. Tumor necrosis factor-related-apoptosis-inducing-ligand (TRAIL) has been shown to have great potential for the treatment of most human tumor cells, while leaving normal cells unharmed. However, some cancers show resistance to TRAIL treatment, leaving a gap in the understanding of its exact etiology.

METHODS

TRAIL-induced resistance to cell death was investigated in pancreatic and lung cancer cell lines. Cell survival was determined by SRB and apoptosis by ELISA-based cell death assay. Activation of bid and caspases were evaluated by Western blotting.

RESULTS

Our study demonstrated that TRAIL significantly suppressed cell survival, by inducing apoptosis in a dose-dependent manner, in the pancreatic cancer BxPC-3 (wild type G12) and lung cancer A549 (G12S) cell lines. In contrast, Panc-1 pancreatic and SK-LU-1 lung cancer cell lines, which have a mutated (G12D) K-ras genotype, were resistant to the actions of TRAIL.

CONCLUSIONS

This study demonstrates an association between TRAIL resistance to apoptosis in human pancreatic and lung cancer cell lines and G12D K-ras(12) mutation.

Genetic and epigenetic alterations of familial pancreatic cancers

BACKGROUND

Little is known about the genetic and epigenetic changes that contribute to familial pancreatic cancers. The aim of this study was to compare the prevalence of common genetic and epigenetic alterations in sporadic and familial pancreatic ductal adenocarcinomas.

METHODS

DNA was isolated from the microdissected cancers of 39 patients with familial and 36 patients with sporadic pancreatic adenocarcinoma. KRAS2 mutations were detected by BstN1 digestion and/or cycle sequencing. TP53 and SMAD4 status were determined by immunohistochemistry on tissue microarrays of 23 archival familial pancreatic adenocarcinomas and in selected cases by cycle sequencing to identify TP53 gene mutations. Methylation-specific PCR analysis of seven genes (FoxE1, NPTX2, CLDN5, P16, TFPI-2, SPARC, ppENK) was done on a subset of fresh-frozen familial pancreatic adenocarcinomas.

RESULTS

KRAS2 mutations were identified in 31 of 39 (80%) of the familial versus 28 of 36 (78%) of the sporadic pancreatic cancers. Positive immunolabeling for p53 was observed in 57% of the familial pancreatic cancers and loss of SMAD4 labeling was observed in 61% of the familial pancreatic cancers, rates similar to those observed in sporadic pancreatic cancers. The mean prevalence of aberrant methylation in the familial pancreatic cancers was 68.4%, which was not significantly different from that observed in sporadic pancreatic cancers.

CONCLUSION

The prevalence of mutant KRAS2, inactivation of TP53 and SMAD4, and aberrant DNA methylation of a seven-gene panel is similar in familial pancreatic adenocarcinomas as in sporadic pancreatic adenocarcinomas. These findings support the use of markers of sporadic pancreatic adenocarcinomas to detect familial pancreatic adenocarcinomas.

Role of Ras signaling in the induction of snail by transforming growth factor-beta

The epithelial-mesenchymal transition (EMT) is a crucial morphological event that occurs during the progression of epithelial tumors. EMT can be induced by transforming growth factor (TGF)-beta in some tumor cells. Here, we demonstrate the molecular mechanism whereby Snail, a key regulator of EMT, is induced by TGF-beta in tumor cells. Snail induction by TGF-beta was highly dependent on cooperation with active Ras signals, and silencing of Ras abolished Snail induction by TGF-beta in pancreatic cancer Panc-1 cells. Transfection of constitutively active Ras into HeLa cells led to induction of Snail by TGF-beta, while representative direct targets of TGF-beta, including Smad7 and PAI-1, were not affected by Ras signaling. Using mitogen-activated protein kinase inhibitors or Smad3 or Smad2 mutants, we found that phosphorylation at the linker region of Smad2/3 was not required for the induction of Snail by TGF-beta. Taken together, these findings indicate that Ras and TGF-beta-Smad signaling selectively cooperate in the induction of Snail, which occurs in a Smad-dependent manner, but independently of phosphorylation at the linker region of R-Smads by Ras signaling.

Lung cancer cell lines harboring MET gene amplification are dependent on Met for growth and survival

Recent clinical successes of small-molecule epidermal growth factor receptor (EGFR) inhibitors in treating advanced non-small cell lung cancer (NSCLC) have raised hopes that the identification of other deregulated growth factor pathways in NSCLC will lead to new therapeutic options for NSCLC. Met, the receptor for hepatocyte growth factor, has been implicated in growth, invasion, and metastasis of many tumors including NSCLC. To assess the functional role for Met in NSCLC, we evaluated a panel of nine lung cancer cell lines for Met gene amplification, Met expression, Met pathway activation, and the sensitivity of the cell lines to short hairpin RNA (shRNA)-mediated Met knockdown. Two cell lines, EBC-1 and H1993, showed significant Met gene amplification and overexpressed Met receptors which were constitutively phosphorylated. The other seven lines did not exhibit Met amplification and expressed much lower levels of Met, which was phosphorylated only on addition of hepatocyte growth factor. We also found a strong up-regulation of tyrosine phosphorylation in beta-catenin and p120/delta-catenin in the Met-amplified EBC-1 and H1993 cell lines. ShRNA-mediated Met knockdown induced significant growth inhibition, G(1)-S arrest, and apoptosis in EBC-1 and H1993 cells, whereas it had little or no effect on the cell lines that do not have Met amplification. These results strongly suggest that Met amplification identifies a subset of NSCLC likely to respond to new molecular therapies targeting Met.

H-REV107-1 stimulates growth in non-small cell lung carcinomas via the activation of mitogenic signaling

H-REV107-1, a known member of the class II tumor suppressor gene family, is involved in the regulation of differentiation and survival. We analyzed H-REV107-1 in non-small cell lung carcinomas, in normal lung, and in immortalized and tumor-derived cell lines. Sixty-eight percent of lung tumors revealed positive H-REV107-1-specific staining. Furthermore, survival analysis demonstrated a significant association of cytoplasmic H-REV107-1 with decreased patient survival. This suggested that H-REV107-1, known as a tumor suppressor, plays a different role in non-small cell lung carcinomas. Knock-down of H-REV107-1 expression in lung carcinoma cells inhibited anchorage-dependent and anchorage-independent growth whereas overexpression of H-REV107-1 induced tumor cell proliferation. Consistent with results of the survival analysis, cytoplasmic localization of the protein was essential for this growth-inducing function. Analysis of signaling pathways potentially involved in this process demonstrated that overexpression of H-REV107-1 stimulated RAS-GTPase activity, ERK1,2 phosphorylation, and caveolin-1 expression in the cell lines analyzed. These results indicate that H-REV107-1 is deficient in its function as a tumor suppressor in non-small cell lung carcinomas and is required for proliferation and anchorage-independent growth in cells expressing high levels of the protein, thus contributing to tumor progression in a subset of non-small cell lung carcinomas.

ATP citrate lyase inhibition can suppress tumor cell growth

Many tumors display a high rate of glucose utilization, as evidenced by 18-F-2-deoxyglucose PET imaging. One potential advantage of catabolizing glucose through glycolysis at a rate that exceeds bioenergetic need is that the growing cell can redirect the excess glycolytic end product pyruvate toward lipid synthesis. Such de novo lipid synthesis is necessary for membrane production and lipid-based posttranslational modification of proteins. A key enzyme linking glucose metabolism to lipid synthesis is ATP citrate lyase (ACL), which catalyzes the conversion of citrate to cytosolic acetyl-CoA. ACL inhibition by RNAi or the chemical inhibitor SB-204990 limits in vitro proliferation and survival of tumor cells displaying aerobic glycolysis. The same treatments also reduce in vivo tumor growth and induce differentiation.

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.

Induction of cytotoxicity in human lung adenocarcinoma cells by 6-O-carboxypropyl-alpha-tocotrienol, a redox-silent derivative of alpha-tocotrienol

Tocotrienols are one of the most potent anticancer agents of all natural compounds and the anticancer property may be related to the inactivation of Ras family molecules. The anticancer potential of tocotrienols, however, is weakened due to its short elimination half life in vivo. To overcome the disadvantage and reinforce the anticancer activity in tocotrienols, we synthesized a redox-silent analogue of alpha-tocotrienol (T3), 6-O-carboxypropyl-alpha-tocotrienol (T3E). We estimated the possibility of T3E as a new anticancer agent against lung adenocarcinoma showing poor prognosis based on the mutation of ras gene. T3E showed cytotoxicity against A549 cells, a human lung adenocarcinoma cell line with a ras gene mutation, in a dose-dependent manner (0-40 microM), whereas T3 and a redox-silent analogue of alpha-tocopherol (T), 6-O-carboxypropyl-alpha-tocopherol (TE), showed much less cytotoxicity in cells within 40 microM. T3E cytotoxicity was based on the accumulation of cells in the G1-phase of the cell-cycle and the subsequent induction of apoptosis. Similar to this event, 24-hr treatment of A549 cells with 40 microM T3E caused the inhibition of Ras farnesylation, and a marked decrease in the levels of cyclin D required for G1/S progression in the cell-cycle and Bcl-xL, a key anti-apoptotic molecule. Moreover, the T3E-dependent inhibition of RhoA geranyl-geranylation is an inducing factor for the occurrence of apoptosis in A549 cells. Our results suggest that T3E suppresses Ras and RhoA prenylation, leading to negative growth control against A549 cells. In conclusion, a redox-silent analogue of T3, T3E may be a new candidate as an anticancer agent against lung adenocarcinoma showing poor prognosis based on the mutation of ras genes.

MRP-1/CD9 gene transduction downregulates Wnt signal pathways

Motility-related protein-1 (MRP-1/CD9) is a transmembrane glycoprotein that has been implicated in cell adhesion, motility, proliferation, and differentiation. It has a functional role as a tumor metastatic suppressor. During tumor progression, a reduction of MRP-1/CD9 gene expression results in tumor cells with a high metastatic potential. However, the mechanism of action of MRP-1/CD9 is still unclear. We studied changes of gene expression in relation to MRP-1/CD9 gene transduction into tumor cell lines, HT1080 and A549, using microarray assays and real-time PCR. Consequently, we have demonstrated that MRP-1/CD9 gene transduction can downregulate expression of several Wnt family genes, such as Wnt1, Wnt2b1 and Wnt5a, and their target genes, including WISP-1 (Wnt-1 induced secreted protein 1), WISP-3, c-Myc, vascular endothelial growth factor-A, and matrix metalloproteinase-26. Western blot analyses also showed that MRP-1/CD9 gene transduction downregulated expression of Wnt1 protein and its target proteins. In addition, a neutralizing anti-MRP-1/CD9 monoclonal antibody inhibited the downregulation of Wnt signal pathways in MRP-1/CD9-transfected cells. The present study has revealed that the MRP-1/CD9 signal is located upstream of the Wnt signal pathways. Therefore, MRP-1/CD9 could suppress cell transformation including epithelial to mesenchymal transition through downregulation of Wnt1, and might suppress tumor metastasis through downregulation of Wnt5a.

LigAmp for sensitive detection of single-nucleotide differences

We developed the LigAmp assay for sensitive detection and accurate quantification of viruses and cells with single-base mutations. In LigAmp, two oligonucleotides are hybridized adjacently to a DNA template. One oligonucleotide matches the target sequence and contains a probe sequence. If the target sequence is present, the oligonucleotides are ligated together and detected using real-time PCR. LigAmp detected KRAS2 mutant DNA at 0.01% in mixtures of different cell lines. KRAS2 mutations were also detected in pancreatic duct juice from patients with pancreatic cancer. LigAmp detected the K103N HIV-1 drug resistance mutation at 0.01% in plasmid mixtures and at approximately 0.1% in DNA amplified from plasma HIV-1. Detection in both systems is linear over a broad dynamic range. Preliminary evidence indicates that reactions can be multiplexed. This assay may find applications in the diagnosis of genetic disorders and the management of patients with cancer and infectious diseases.

Proteomic analysis of eIF-5A in lung adenocarcinomas

We examined the eIF-5A protein expression in 93 lung adenocarcinomas and 10 uninvolved lung samples using quantitative two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) analysis with identification by mass spectrometry and 2-D Western blots. The same tissue samples were examined for the eIF-5A mRNA expression using oligonucleotide microarrays, and the cellular localization of the eIF-5A protein was examined using immunohistochemical analysis on tissue arrays. Higher eIF-5A protein expression was present in tumors showing poor differentiation, 12/13(th) codon K-ras mutations, p53 nuclear accumulation, and tumors with positive lymphocytic response. The eIF-5A mRNA was also significantly increased in lung adenocarcinomas compared to normal lung, but the eIF-5A protein expression was not correlated to its mRNA levels indicating that the increase in the eIF-5A protein expression in lung tumors is post-transcriptionally/translationally/post-translationally regulated. Patients having a higher eIF-5A protein expression showed a relatively poorer survival suggesting the use of eIF-5A as prognostic marker in lung adenocarcinoma. Moreover, the investigation on agents that inhibit eIF-5A function is encouraged.

NF-kappaB blockade and oncogenic Ras trigger invasive human epidermal neoplasia

The nuclear factor NF-kappaB and oncogenic Ras can alter proliferation in epidermis, the most common site of human cancer. These proteins are implicated in epidermal squamous cell carcinoma in mice, however, the potential effects of altering their function are uncertain. Whereas inhibition of NF-kappaB enhances apoptosis in certain tumours, blockade of NF-kappaB predisposes murine skin to squamous cell carcinoma. Because therapeutics inhibiting Ras and NF-kappaB pathways are being developed to treat human cancer, it is essential to assess the effects of altering these regulators. The medical relevance of murine studies is limited, however, by differences between mouse and human skin, and by the greater ease of transforming murine cells. Here we show that in normal human epidermal cells both NF-kappaB and oncogenic Ras trigger cell-cycle arrest. Growth arrest triggered by oncogenic Ras can be bypassed by IkappaBalpha-mediated blockade of NF-kappaB, generating malignant human epidermal tissue resembling squamous cell carcinoma. Human cell tumorigenesis is dependent on laminin 5 and alpha6beta4 integrin. Thus, IkappaBalpha circumvents restraints on growth promotion induced by oncogenic Ras and can act with Ras to induce invasive human tissue neoplasia.

Short hairpin type of dsRNAs that are controlled by tRNA(Val) promoter significantly induce RNAi-mediated gene silencing in the cytoplasm of human cells

The post-transcriptional gene silencing in animals and plants is called RNA interference (RNAi). Guides for the sequence-specific degradation of mRNA are 21-nt small interfering RNAs (siRNAs) that are generated by Dicer-dependent cleavage from longer double-stranded RNAs (dsRNAs). To examine the relationship between the localization of dsRNA and the target cleavage of RNAi in human cells, we constructed five kinds of dsRNA expression vector that were controlled by tRNA(Val) or U6 promoter. Transcripts of tRNA-dsRNA were consistently localized in the cytoplasm and were efficiently processed by Dicer. In contrast, transcripts of tRNA-dsRNA were not processed in cells that expressed Dicer-directed ribozymes. In addition, transcripts of U6-dsRNA were basically localized in the nucleus and were not significantly processed, unless the transcripts of U6-dsRNAs possessed a microRNA-based loop motif: in the latter case, U6-dsRNAs with a microRNA-based loop were transported to the cytoplasm and were effectively processed. More over, tRNA-dsRNA directed against a mutant k-ras transcript cleaved its target mRNA efficiently in assays of RNAi not only in vitro with a cytoplasmic extract but also in vivo. Therefore, it appears that RNAi in human cells occur in the cytoplasm. Importantly, the same tRNA-dsRNA did not affect the degradation of the normal k-ras mRNA in vitro and in vivo. Our tRNA-dsRNA technology should be a powerful tool for studies of the mechanism of RNAi and the functions of various genes in mammalian cells with potential utility as a therapeutic agent.

Hydrocarbon carcinogens evade cellular defense mechanism of G1 arrest in nontransformed and malignant lung cell lines

In previous studies using human breast carcinoma cells (MCF-7) and human colon carcinoma cells (RKO) we have shown that, in response to treatment with hydrocarbon carcinogens, these cell lines failed to undergo a p53-mediated cell cycle arrest in G1 phase; rather, the cells were accumulated in the S phase with damaged DNA, a situation that may lead to replication of DNA on a damaged template, resulting in the enhanced frequency of mutations in the daughter cells. This has been termed a stealth effect. In the present work we have demonstrated that the stealth effect also pertains for lung cells. In E10 nontransformed mouse lung type II cells, two potent hydrocarbon carcinogens, benzo[a]pyrene dihydrodiol epoxide and benzo[g]chrysene dihydrodiol epoxide, damaged DNA as suggested by retardation in S phase, but did not cause G1 arrest, in contrast to the positive control, actinomycin D. Human lung adenocarcinoma A549 cells, with normal p53, likewise exhibited G1 arrest after actinomycin D, but not after treatment with the diol epoxides. Several human lung cancer cell lines with absent or mutant p53, such as H358, H1734, and H82, exhibited no G1 arrest after any of the compounds. However, lung H441 adenocarcinoma cells, with a mutation in exon 5, codon 158 of p53, exhibited partial G1 arrest after the diol epoxides as well as actinomycin D, and H2030 adenocarcinoma cells did not show G1 arrest after any of the chemicals despite a normal p53. The stealth effect of evasion of G1 arrest may contribute to initiation of lung adenocarcinomas and to progression of tumors. A role in resistance to chemotherapy by certain drugs is also likely.

Isolation and characterization of a novel bladder cancer cell line: inhibition by epidermal growth factor

A novel continuous cell line, designated BC3c, was established from a surgical biopsy of an invasive solid transitional cell carcinoma of the bladder derived from an 82-yr-old Caucasian female. BC3c cells were near-triploid bearing multiple structural and numerical chromosome anomalies. The epithelial origin of the cancer cells was indicated by the expression of cytokeratins 8 and 19 as well as by the absence of mesenchymal markers. Polymerase chain reaction-restriction-fragment length polymorphisms and single-strand conformation polymorphism mutation detection assays did not reveal any mutations in H-ras codon 12 and K-ras codons 12 and 13. In addition, no mutation in specific hot-spot codons of the p53 gene and no accumulation of the p53 protein were observed. BC3c cells grew rapidly in vitro, even in the absence of exogenous growth factors, because they were found to stimulate their growth in an autocrine manner. BC3c cells were found to express the epidermal growth factor-receptor (EGF-r) abundantly, but in contrast to other established bladder cancer cell lines, human recombinant epidermal growth factor inhibited the cells' proliferation in vitro. These features render the newly established bladder cancer cell line BC3c a useful tool for further experimentation.

The use of capillary electrophoresis for point-mutation screening

Advances in capillary electrophoresis technology over the past three years have been rapid. Capillary electrophoresis offers high-throughput, high-resolution, automatic operation and on-line detection with automatic data acquisition, and this has stimulated its application to the analysis of DNA mutations. Many different PCR-based DNA-mutation assays have been developed for unknown and known mutations. This article compares conventional PCR-based mutation-detection assays with the methods developed for use with capillary electrophoresis. Future trends for mutation detection using capillary electrophoresis are also assessed, with a special emphasis on totally integrated, microchip capillary-electrophoresis-based mutation-detection systems.

Genotypic selection methods for the direct analysis of point mutations

Genotypic selection enriches a particular DNA sequence relative to another closely-related DNA sequence based only on a change of one or a few bases. This review is a survey of the genotypic selection methods that have the sensitivity to detect rare point mutations. These methods are primarily being used to study mutations caused by environmental mutagens; however, the ability to detect and measure very minor DNA sequence populations is likely to further research efforts in many fields. The approaches for allele-selection have intrinsic strengths and weaknesses, and vary greatly in sensitivity. The most sensitive method is Restriction Fragment Length Polymorphism/Polymerase Chain Reaction (RFLP/PCR) by which mutant fractions as low as 1 mutant allele in 10(8) wild-type alleles can be detected. The RFLP/PCR approach is presented as a prototype genotypic selection method. Genotypic selection methods are categorized in terms of those that (1) selectively destroy the abundant or wild-type allele, (2) selectively amplify the rare or mutant allele, or (3) spatially separate the alleles. Issues relevant to the further development of genotypic selection methods include initial DNA pool size, strategies to eliminate the bulk of extraneous DNA, the use of an internal copy number standard in quantitative PCR, the fidelity of thermostable DNA polymerases, and the effective use of PCR in linking two or more genotypic selection techniques. We conclude that proficient genotypic selection requires more than one allele-enrichment technique with at least one of these preceding a high-fidelity PCR amplification step.

Analysis of disease-causing genes and DNA-based drugs by capillary electrophoresis. Towards DNA diagnosis and gene therapy for human diseases

Rapid progress in the Human Genome Project has stimulated investigations for gene therapy and DNA diagnosis of human diseases through mutation or polymorphism analysis of disease-causing genes and has resulted in a new class of drugs, i.e., DNA-based drugs, including human gene, disease-causing gene, antisense DNA, DNA vaccine, triplex-forming oligonucleotide, protein-binding oligonucleotides, and ribozyme. The recent development of capillary electrophoresis technologies has facilitated the application of capillary electrophoresis to the analysis of DNA-based drugs and the detection of mutations and polymorphism on human genes towards DNA diagnosis and gene therapy for human diseases. In this article the present state of studies on the analysis of DNA-based drugs and disease-causing genes by capillary electrophoresis is reviewed. The paper gives an overview of recent progress in the Human Genome Project and the fundamental aspects of polymerase chain reaction-based technologies for the detection of mutations and polymorphism on human genes and capillary electrophoresis techniques. Attention is mainly pad to the application of capillary electrophoresis to polymerase chain reaction analysis, restriction fragment length polymorphism, single strand conformational polymorphism, variable number of tandem repeat, microsatellite analysis, hybridization technique, and monitoring of DNA-based drugs. Possible future trends are also discussed.

Application of capillary gel electrophoresis to the diagnosis of the aldehyde dehydrogenase 2 genotype

This study dealt with the application of capillary gel electrophoresis (CGE) to diagnosis of the aldehyde dehydrogenase 2 (ALDH-2) genotype. Electrophoresis was performed on a low cross-linked polyacrylamide gel ¿3% T [g acrylamide+g Bis (N,N'-methylenebisacrylamide)], 0.5% C (g Bis/% T)¿ in 100 mM Tris-borate buffer (pH 8.3) at -10 kV with on-column UV detection (260 nm). During the PCR reaction, DNA from the wild-type allele generated a MboII restriction site, which is an amplification created restriction site. This did not occur, however, with DNA fragments from the mutant allele. Therefore, determination of the heterozygous genotype, the coexistence of wild-type and mutant alleles, was easily possible. Analysis of the MboII restriction digests of the PCR products was completed in less than 20 min, showing two peaks corresponding to fragments of 125 (cleaved) and 135 (uncleaved) base pairs (bp), respectively. On the other hand, determination of the homozygous genotype, wild-type or mutant, was difficult in one electrophoresis run. The CGE of the MboII restriction digests gave a single peak and the identification, cleaved or uncleaved, was difficult under our experimental conditions. However, the addition of aliquots of the PCR reaction mixture to the restriction digests, followed by re-electrophoresis, allowed successful diagnosis, yielding two peaks (cleaved and uncleaved) for the wild-type and one peak (uncleaved) for the mutant allele. This study demonstrated that CGE offers a high-speed, high-resolution analytical tool for determining genetic types, as compared with the conventional slab gel methodologies.