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Anil K Rustgi

Publications and source records attributed to Anil K Rustgi.

47 records · Page 3Linked to original sources
PubMed2003

Telomerase induces immortalization of human esophageal keratinocytes without p16INK4a inactivation.

Normal human somatic cells have a finite life span and undergo replicative senescence after a limited number of cell divisions. Erosion of telomeric DNA has emerged as a key factor in senescence, which is antagonized during cell immortalization and transformation. To clarify the involvement of telomerase in the immortalization of keratinocytes, catalytic subunit of telomerase (hTERT) expression was restored in normal human esophageal epithelial cells (EPC2). EPC2-hTERT cells overcame senescence and were immortalized without p16INK4a genetic or epigenetic alterations. p16INK4a was expressed at moderate levels and remained functional as evidenced by induction with UV treatment and binding to cyclin-dependent kinase 4 and 6. There were no mutations in the p53 gene, and p53 was functionally intact. Importantly, senescence could be activated in the immortalized EPC2-hTERT cells by overexpression of oncogenic H-ras or p16INK4a. Furthermore, the EPC2-hTERT cells yielded basal cell hyperplasia in an innovative organotypic culture system in contrast to a normal epithelium from parental cells. These comprehensive results indicate that the expression of telomerase induces immortalization of normal human esophageal keratinocytes without inactivation of p16INK4a/pRb pathway or abrogation of the p53 pathway.

Cell Differentiation↗
PubMed2002

Epidermal growth factor receptor mediates increased cell proliferation, migration, and aggregation in esophageal keratinocytes in vitro and in vivo.

Epidermal growth factor receptor (EGFR) overexpression is observed in a number of malignancies, especially those of esophageal squamous cell origin. However, little is known about the biological functions of EGFR in primary esophageal squamous epithelial cells. Using newly established primary human esophageal squamous epithelial cells as a platform, we overexpressed EGFR through retroviral transduction and established novel three-dimensional organotypic cultures. Additionally, EGFR was targeted in a cell type- and tissue-specific fashion to the esophageal epithelium in transgenic mice. EGFR overexpression in primary esophageal keratinocytes resulted in the biochemical activation of Akt and STAT pathways and induced enhanced cell migration and cell aggregation. When established in organotypic culture, EGFR-overexpressing cells had evidence of epithelial cell hyperproliferation and hyperplasia. These effects were also observed in EGFR-overexpressing transgenic mice and the esophageal cell lines established thereof. In particular, EGFR-induced effects upon aggregation appear to be mediated through the relocalization of p120 from the cytoplasm to the membrane and increased interaction with E-cadherin. EGFR modulates cell migration through the up-regulation of matrix metalloproteinase 1. Taken together, the functional effects of EGFR overexpression help to explain its role in the initiating steps of esophageal squamous carcinogenesis.

Animals↗
PubMed2002

Wnt-1 but not epidermal growth factor induces beta-catenin/T-cell factor-dependent transcription in esophageal cancer cells.

beta-Catenin plays an important role in signal transduction pathways that regulate cellular differentiation and proliferation. The increased concentration of this protein in the cytoplasm favors its binding to the T-cell factor (TCF) family of DNA-binding proteins, and it subsequently translocates to the nucleus, where it induces transcription of specific genes. We explored mechanisms that lead to activation of beta-catenin/TCF-dependent transcription in esophageal squamous cell carcinoma (ESCC) independent of adenomatous polyposis coli and beta-catenin mutation. Electrophoresis mobility shift assay demonstrated that TCF4 and beta-catenin form a complex and have DNA binding activity. However, there was no constitutive activation of beta-catenin/TCF-dependent transcription. Coculture experiments demonstrated that Wnt-1, but not Wnt-5A and Wnt-7A, activated the TCF reporter gene. Additionally, when cultured with Wnt-1-conditioned media, ESCC cell lines showed an accumulation of beta-catenin in the cytoplasm. Although both Wnt and epidermal growth factor inactivate glycogen synthase kinase 3beta, activation of epidermal growth factor receptor did not stabilize beta-catenin. A comparison of extracellular stimuli suggests that specific Wnt family members stabilize beta-catenin with resulting activation of TCF-dependent transcription in ESCC.

Animals↗
PubMed2002

A mouse model of human oral-esophageal cancer.

Squamous cancers of the oral cavity and esophagus are common worldwide, but no good genetically based animal model exists. A number of environmental factors as well as genetic alterations have been identified in these cancers, yet the specific combination of genetic events required for cancer progression remains unknown. The Epstein-Barr virus ED-L2 promoter (L2) can be used to target genes in a specific fashion to the oral-esophageal squamous epithelium. To that end, we generated L2-cyclin D1 (L2D1(+)) mice and crossbred these with p53-deficient mice. Whereas L2D1(+) mice exhibit a histologic phenotype of oral-esophageal dysplasia, the combination of cyclin D1 expression and p53 deficiency results in invasive oral-esophageal cancer. The development of the precancerous lesions was significantly reversed by the application of sulindac in the drinking water of the L2D1(+)/p53(+/-) mice. Furthermore, cell lines derived from oral epithelia of L2D1(+)/p53(+/-) and L2D1(+)/p53(-/-) mice, but not control mice, formed tumors in athymic nude mice. These data demonstrate that L2D1(+)/p53(+/-) mice provide a well-defined, novel, and faithful model of oral-esophageal cancer, which allows for the testing of novel chemopreventive, diagnostic, and therapeutic approaches.

Animals↗
PubMed2002

Treatment and prevention of intraepithelial neoplasia: an important target for accelerated new agent development.

Precancer or intraepithelial neoplasia (IEN) is a noninvasive lesion that has genetic abnormalities, loss of cellular control functions, and some phenotypic characteristics of invasive cancer and that predicts for a substantial likelihood of developing invasive cancer. The AACR Task Force on the Treatment and Prevention of IEN has delineated the relationship between IEN and cancer risk as well as the clinical benefit that can be derived from reducing IEN burden. Although several effective endoscopic and surgical treatments for IEN have become standard medical practice, these interventions can confer morbidity and do not treat the entire epithelial field at risk. The incidence of many epithelial cancers is continuing to rise, the number of individuals at risk is increasing with the aging population, and the rapid advancement of imaging and molecular diagnostics is bringing to light precancers that were heretofore clinically silent. There is therefore an urgent need to rapidly develop new treatment and prevention agents for IEN. The AACR IEN Task Force recommends focusing on established precancers as the target for new agent development because of the close association between dysplasia and invasive cancer and because a convincing reduction in IEN burden provides patient benefit by reducing cancer risk and/or by decreasing the need for invasive interventions. The IEN Task Force proposes several clinical trial designs that provide practical and feasible approaches to the rapid development of new agents to treat and prevent precancer.

Antineoplastic Agents↗
PubMedDate not supplied

Characterization of proteins in human pancreatic cancer serum using differential gel electrophoresis and tandem mass spectrometry.

The purpose of this study was to develop techniques for identifying cancer biomarkers in human serum using differential in-gel electrophoresis (DIGE), and characterizing the protein biomarkers using tandem mass spectrometry (MS/MS). A major problem in profiling protein expression by DIGE comes from the presence of high concentrations of a small number of proteins. Therefore, serum samples were first chromatographed using an immunoaffinity HPLC column (Agilent Technologies), to selectively remove albumin, immunoglobulins, transferrin, haptoglobin, and antitrypsin. Serum samples from three individuals with pancreatic cancer and three individuals without cancer were compared. Serum samples were processed using the immunoaffinity column. Differential protein analysis was performed using DIGE. A total of 56 protein spot-features were found to be significantly increased and 43 significantly decreased in cancer serum samples. These spot features were excised, trypsin digested, and analyzed by MALDI/TOF/TOF (4700 Proteomics Analyzer, Applied Biosystems). We identified 24 unique proteins that were increased and 17 unique proteins that were decreased in cancer serum samples. Western blot analysis confirmed increased levels of several of these proteins in the pancreatic cancer serum samples. In an independent series of serum samples from 20 patients with pancreatic cancer and 14 controls, increased levels of apolipoprotein E, alpha-1-antichymotrypsin, and inter-alpha-trypsin inhibitor were found to be associated with pancreatic cancer. These results suggest that affinity column enrichment and 2-D DIGE can be used to identify numerous proteins differentially expressed in serum from individuals with pancreatic cancer.

Adult↗
PubMedDate not supplied

Clinical trial resources on the internet must be designed to reach underrepresented minorities.

PURPOSE: Internet-based clinical trial information services are being developed to increase recruitment to studies. However, there are limited data that evaluate their ability to reach elderly and underrepresented minority populations. This study was designed to evaluate the ability of an established clinical trials registry to reach these populations based on expected Internet use. PATIENTS AND METHODS: This study compares general Internet users to participants who enrolled in an Internet based colorectal cancer clinical trials registry established by OncoLink (www.oncolink.org) and the National Colorectal Cancer Research Alliance. Observed rates of demographic groupings were compared to those established for general Internet users. RESULTS: Two thousand, four hundred and thirty-seven participants from the continental United States used the Internet to register for the database. New England, the Mid-Atlantic region, and the Southeast had the highest relative frequency of participation in the database, whereas the Upper Midwest, California, and the South had the lowest rates. Compared to general Internet users, there was an overrepresentation of women (73% vs. 50%) and participants over 55 years old (27% vs. 14%). However, there was an underrepresentation of minorities (10.3% vs. 22%), particularly African Americans (3.1% vs. 8%) and Hispanics (2.8% vs. 9%). DISCUSSION: The Internet is a growing medium for registry into clinical trials databases. However, even taking into account the selection bias of Internet accessibility, there are still widely disparate demographics between general Internet users and those registering for clinical trials, particularly the underrepresentation of minorities. Internet-based educational and recruitment services for clinical trials must be designed to reach these underrepresented minorities to avoid selection biases in future clinical trials.

Black or African American↗