Human group C adenoviruses can infect many cell types, and this is due to the widespread expression of their receptor, the coxsackievirus and adenovirus receptor (CAR). Adenovirus vectors for cancer gene therapy could be significantly improved if their tropism were restricted to tumor cells. In this work, previously identified peptides that target human papillomaviruses (HPV)-transformed cells were inserted into the HI loop of a non-CAR-binding fiber. These modified fiber proteins were able to assemble into adenovirus particles. We demonstrated that these modifications ablated the native tropism of adenovirus type 5, and these modified adenoviruses were shown to preferentially transduce HPV-transformed cell lines.

The E6 protein of cancer-associated human papillomavirus type 16 (16E6) binds to p53 and, in association with E6AP, promotes its degradation through the ubiquitin-proteasome pathway. The aim of this work was to develop monoclonal antibodies against 16E6 and to test their effect on the binding of 16E6 to p53 and E6AP, and on the degradation of p53. It was shown that an antibody directed against the N terminus of 16E6 inhibited E6AP-dependent binding to p53 and degradation of p53, whereas two different antibodies directed to the second zinc-binding domain of 16E6 reduced 16E6 E6AP-independent binding to p53 and binding to E6AP but not degradation of p53.

'High-risk' human papilloma viruses (HPVs) cause cervical tumours. In order to treat these tumours therapeutic approaches must be developed that efficiently target the tumour cells. Using phage display, we selected tumour-targeting peptides from a library of constrained nonamer peptides presented multivalently on pVIII of M13. Three different consensus peptide sequences were isolated by biopanning on HPV16-transformed SiHa cells. The corresponding phage-peptides targeted and were internalized in HPV16-transformed SiHa and CaSki cells as well as in HPV18-transformed HeLa cells, but failed to bind a panel of normal or transformed cell lines. Two of the three selected peptides targeted cells only when presented on phage particles in a constrained conformation. However, all three peptides retained their targeting capacity when presented on the reporter protein enhanced green fluorescent protein (EGFP) in a monovalent form. These peptides may be useful for the design of drug or gene delivery vectors for the treatment of cervical cancer. Copyright (c) 2004 John Wiley & Sons, Ltd.

Chromosomal region 18q21 is frequently deleted in colorectal cancer (CRC) and is associated with poor prognosis. Potential tumor suppressor mechanisms altered by 18q21 deletion include mediation of TGFβ signaling by SMADs. Following the definition of SMAD4 deletion as a negative predictive marker for chemotherapy benefit in patients with CRC, we aimed to evaluate the clinical relevance of the deletion of other SMAD genes clustered in this region: SMAD2 and SMAD7 in 264 CRC biopsies from a previous clinical study. In contrast to SMAD2 deletion, for which no clinical relevance was observed, hazard ratios (HR) in a multivariate analysis associated with SMAD7 deletion [overall survival (OS): HR = 0.43, p = 0.0012; disease‐free survival (DFS): HR = 0.50, p = 0.0033] indicated a favorable outcome for these patients. In addition, SMAD7 duplication had a hazardous effect on survival [OS: HR = 2.10, p = 0.020; DFS: HR = 2.06, p = 0.015]. Moreover, the HRs associated with one additional copy of SMAD7 were 1.76, p = 0.00024 [OS] and 1.64, p = 0.00048 [DFS] respectively, showing a graded effect of SMAD7 on patient outcome depending on gene copy number that suggests a dose‐and‐effect basis. Since SMAD7 blocks TGFβ signaling, these data are consistent with the loss of SMAD7 rendering carcinoma cells more sensitive to cell growth arrest/apoptotic effect of TGFβ, whereas gain of SMAD7 function might result in TGFβ resistance, thereby emphasizing the role of TGFβ in tumor suppression. © 2003 Wiley‐Liss, Inc.

The gene for the transducer of transforming growth factor-beta/bone morphogenetic protein signalling SMAD4, a potential suppressor of colorectal carcinogenesis, is located at the chromosomal region 18q21. In order to evaluate the clinical relevance of SMAD4 deletion, gene copy alterations were determined by copy dosage using real-time quantitative PCR in 202 colorectal tumour biopsies from a previous randomised study of adjuvant chemotherapy. Patients with normal SMAD4 diploidy turned out to have a three-fold higher benefit of 5-fluorouracil-based adjuvant chemotherapy with a border line significance (overall survival: 3.23, P=0.056; disease-free survival: 2.89, P=0.045). These data are consistent with the previous observation that patients whose cancer had retention of the 18q21 region had a significantly higher benefit from 5-fluorouracil-based therapy. Moreover, these results may provide a refinement at the gene level of the clinical relevance of 18q21 deletion, thereby suggesting SMAD4 as a predictive marker in colorectal cancer. This data also indicate that integrity of this component of the transforming growth factor-beta/bone morphogenetic protein signalling pathway may be a critical factor for benefit of chemotherapy in patients with colorectal cancer.

Deletions of chromosome band 18q21 appear with very high frequency in a variety of carcinomas, especially in colorectal cancer. Potent tumor suppressor genes located in this region encode transforming growth factor β (TGF‐β) signal transducers SMAD2 and SMAD4, and inactivation of either one leads to impaired TGF‐β‐mediated cell growth/apoptosis. Following the assignment of SMAD7 to 18q21, we first refined the SMAD7 gene position within this region by genetically mapping SMAD7 between SMAD2 and SMAD4. Further, to compare the respective frequencies of genetic alterations of these three SMAD genes in colorectal cancer, we undertook a large‐scale evaluation of the copy status of each of these genes on DNA samples from colorectal tumor biopsy material. Among a subset of 233 DNA samples for which data were available for all four genes, SMAD4, SMAD2, and the nearby gene DCC showed high deletion rates (66%, 64%, and 59%, respectively), whereas SMAD7 was deleted in only 48% of the tumors. Unexpectedly, we found some gene duplications; SMAD7 appears to be more frequently amplified (10%) than the three other genes (4–7%). Compiled data for SMAD genes in each tumor show that the most common combination (26% of all the tumors) consists of the simultaneous deletions of SMAD2 and SMAD4 associated with normal diploidy or even duplication of SMAD7. Since SMAD7 normally counteracts SMAD2 and SMAD4 in TGF‐β signaling, we hypothesize that the tumor might not benefit from simultaneous SMAD7 inactivation, thereby exerting selective pressure to retain or even to duplicate the SMAD7 gene. © 2001 Wiley‐Liss, Inc.