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Biomedical subjects

K Tabiti

Publications and source records attributed to K Tabiti.

8 recordsLinked to original sources
PubMed2004

Quantitative detection of cytokeratin 20 mRNA expression in bladder carcinoma by real-time reverse transcriptase-polymerase chain reaction.

OBJECTIVES: To determine cytokeratin 20 (CK 20) expression in tumor tissue, normal urothelial tissue, bladder washings, and urine from patients with urothelial carcinoma by real-time reverse transcriptase-polymerase chain reaction using the LightCycler Instrument. METHODS: Urine, bladder washings, tumor, and normal urothelial tissue were obtained from 33 patients with bladder carcinoma. RNA was subsequently extracted. Twenty tissue samples from healthy volunteers were used as controls. Real-time reverse transcriptase-polymerase chain reaction with the LightCycler was performed using fluorescence-labeled CK 20 primers as the target gene and the porphobilinogen deaminase housekeeping gene as the internal standard. RESULTS: CK 20 mRNA expression was detected in all samples investigated. CK 20 expression in the tissue and urine samples from patients with tumor was significantly increased compared with that in normal urothelial tissue (P = 0.028) or urine from the negative control group (P = 0.012). The average CK 20 expression was 70,140 arbitrary units (AU) in tumor tissue (30,533 AU in urine from patients with tumor) and 8460 AU in normal urothelial tissue (2234 AU in normal urine). A stage-related difference in CK 20 mRNA expression was observed in tumor tissue (P = 0.027) and for tumor grade G1-G2 versus G3 (P = 0.03). CONCLUSIONS: CK 20 mRNA expression levels in tissue and urine were elevated in patients with urothelial carcinoma compared with the levels in healthy individuals. CK 20 expression was also detectable in normal urine or normal urothelial tissue, but at significantly lower levels than in tumor samples. Fluorescence-labeled quantitative polymerase chain reaction using the LightCycler helped to differentiate between low-level CK 20 expression in normal urothelial tissue and the levels in tumor tissue samples. CK 20 might be an excellent and sensitive marker for tumor monitoring and routine follow-up in patients with transitional cell carcinoma.

Aged↗
PubMed2001

Quantitative reverse transcription-polymerase chain reaction detection of cytokeratin 20 in noncolorectal lymph nodes.

PURPOSE: Unexpected reverse transcription-PCR detection of cytokeratin 20 (CK20) in samples from healthy individuals and cancer types not expected to express CK20 has cast uncertainty on the role of CK20 as a specific marker of disseminated colorectal cells. We aimed to clarify the specificity of CK20 by examining its expression profile by real-time reverse transcription-PCR. EXPERIMENTAL DESIGN: A quantitative real-time PCR assay on the LightCycler instrument was developed and used to examine CK20 expression in tumors and lymph nodes from subjects with colorectal and breast carcinoma, head and neck and vulval squamous cell carcinoma, and melanoma. To select a method for reproducible quantification, four approaches were evaluated. RESULTS: The developed assay allowed rapid, convenient-to-use, specific, sensitive, and reproducible CK20 quantification amenable to large-scale analysis. For quantity calculation, an efficiency-adjusted relative ratio method was selected that controls for RNA loading and integrity as well as inefficient PCR reactions and provides a platform for standardization across laboratories. Using this assay, we detected CK20 in 41 of 89 (46%) lymph nodes from noncolorectal cancer types. There was a strong association between CK20 detection and lymph node metastasis determined by histology (P < 0.0001). Quantitatively, CK20 expression levels in colorectal cancer lymph nodes significantly exceeded the levels obtained in lymph nodes of extracolonic carcinomas (P < 0.05). Mean CK20 levels in lymph nodes and tumors from subjects with colorectal and breast cancers were similar in a tumor-type specific fashion. CONCLUSIONS: These results characterize low-level, epithelial cell-specific CK20 expression in infiltrated lymph nodes from subjects with noncolorectal cancer types and demonstrate the potential advantages of detecting circulating epithelial cells by quantitative PCR.

Biomarkers, Tumor↗
PubMed1996

Novel alternative splicing predicts a secreted extracellular isoform of the human receptor-like protein tyrosine phosphatase LAR.

RT-PCR was used to examine the expression of LAR (encoding the leukocyte-common antigen-related protein tyrosine phosphatase) in normal human colon mucosa, and colon polyps and tumors. Although the LAR protein was not detected in the colon in a previous immunohistochemical study, amplification of a region of LAR between the most membrane proximal (eighth) fibronectin type-III (FN-III) repeat and the transmembrane domain demonstrated LAR expression in all samples, but showed no difference in expression within matched samples from each patient examined. An additional minor fragment amplified in all reactions was consistently observed in colon and various cell line samples using this and two other LAR-specific sets of primers. Cloning and sequencing of the fragment identified it as deriving from a novel alternatively spliced form of LAR containing a retained intron of 85 bp. This intron encodes an additional 13 amino acids followed by an in-frame stop codon, thus its retention is predicted to give rise to a secreted LAR extracellular region isoform(s). LAR transcripts containing the intron were detected by RNase protection assay of colon samples and were present in most human tissues examined by Northern analysis. A protein in colon tumor extract was recognized by antiserum raised to the intron-encoded sequence. Soluble isoforms of the LAR extracellular immunoglobulin (Ig)-like/FN-III repeat-containing region could have a biological function distinct from those isoforms localized at the cell surface and/or coupled to intracellular phosphatase activity.

Alternative Splicing↗
PubMed1995

Increased mRNA expression of the receptor-like protein tyrosine phosphatase alpha in late stage colon carcinomas.

The protein tyrosine phosphatase alpha (PTP alpha) mRNA level in paired samples of late stage (Dukes' D) colorectal tumors and adjacent normal colon mucosa was quantified by RNase protection assays. After normalization against 18S RNA or beta-actin mRNA level, a 2-10-fold increase in PTP alpha mRNA was detected in 10 of 14 tumors (approximately 70%) compared to mucosa. In situ hybridization of digoxigenin-labelled antisense PTP alpha RNA to tumor and mucosa sections produced a signal only in neoplastic cells of the tumor sample, consistent with the high increase in PTP alpha mRNA detected by RNase protection assays of some of the tumors. This is the first report suggesting an association of a protein tyrosine phosphatase with colorectal carcinoma. PTP alpha is a receptor-like PTP thought to be involved in regulating cell proliferation. Its oncogenic properties when overexpressed in cultured fibroblasts suggest that PTP alpha overexpression could contribute to the tumorigenic process in colon carcinoma.

Adenocarcinoma↗
PubMed1991

Two-step affinity purification of U7 small nuclear ribonucleoprotein particles using complementary biotinylated 2'-O-methyl oligoribonucleotides.

U7 snRNP is a low-abundance small nuclear ribonucleoprotein particle essential for 3' processing of replication-dependent histone pre-mRNA. We have developed a two-step purification of the particle from TB21 mouse mastocytoma cell nuclear extracts, with about a 20% overall yield, using affinity binding to 2'-O-methyl oligoribonucleotides. The purified particle is homogeneous with respect to RNA content. SDS/PAGE of the U7 snRNP proteins revealed a full complement of the standard core proteins (B, DD', E, F, and G) found in the majority of snRNPs. In addition, two U7-specific polypeptides of 14 kDa and 50 kDa were identified. Summation of the molecular masses of the identified components of the U7 particle yields a particle mass of 249 kDa, in approximate agreement with estimates from sucrose gradient sedimentation (261 kDa) and nondenaturing gradient PAGE (217 kDa).

Animals↗
PubMedDate not supplied

Her-2/neu expression in breast cancer--A comparison of different diagnostic methods.

BACKGROUND: Determination of Her-2/neu overexpression in breast cancer has previously been shown to be of prognostic significance. In this study, Her-2/neu expression in breast cancer was characterised by real-time PCR (RLT-PCR) based LightCycler-HER-2/neu DNA Quantification with immunohistochemistry (IHC) and fluorescence in situ hybridisation (FISH). MATERIAL AND METHODS: Fifteen specimens of invasive breast cancer - whole tissue sections as well as microdissected tumour cells - were subjected to RLT-PCR. Additionally, IHC and FISH were performed. RESULTS: Her-2/neu overexpression was detected by FISH and by real-time PCR in the same tumours. In contrast, IHC revealed discordant results. CONCLUSION: Determination of Her-2/neu amplification by real-time PCR is a sensitive and specific method with some advantages over FISH. This method is simple and reliable and has the potential of categorizing those tumours with borderline Her-2/neu overexpression as determined by IHC.

Breast Neoplasms↗