Activated T cells regulate bone loss and joint destruction in adjuvant arthritis through osteoprotegerin ligand

Bone remodelling and bone loss are controlled by a balance between the tumour necrosis factor family molecule osteoprotegerin ligand (OPGL) and its decoy receptor osteoprotegerin (OPG). In addition, OPGL regulates lymph node organogenesis, lymphocyte development and interactions between T cells and dendritic cells in the immune system. The OPGL receptor, RANK, is expressed on chondrocytes, osteoclast precursors and mature osteoclasts. OPGL expression in T cells is induced by antigen receptor engagement, which suggests that activated T cells may influence bone metabolism through OPGL and RANK. Here we report that activated T cells can directly trigger osteoclastogenesis through OPGL. Systemic activation of T cells in vivo leads to an OPGL-mediated increase in osteoclastogenesis and bone loss. In a T-cell-dependent model of rat adjuvant arthritis characterized by severe joint inflammation, bone and cartilage destruction and crippling, blocking of OPGL through osteoprotegerin treatment at the onset of disease prevents bone and cartilage destruction but not inflammation. These results show that both systemic and local T-cell activation can lead to OPGL production and subsequent bone loss, and they provide a novel paradigm for T cells as regulators of bone physiology.

Preliminary immunocytochemical studies of MDR-1 and MDR-3 Pgp expression in B-cell leukaemias

P-glycoproteins (Pgps) belong to the family of ATP binding cassette (ABC) transporter proteins. In humans two Pgp genes have been identified; mdr-1 and mdr-3. Classical Multiple Drug Resistance (MDR) is associated with over expression of the mdr-1 gene product, P-170. No role for mdr-3 in MDR has yet been proven. However there is evidence that mdr-3 overexpression may be associated with drug resistance in certain B-cell lymphocytic leukaemias. In an immunocytochemical study we have looked at a selection of B-cell leukaemias for mdr-1 and mdr-3 encoded Pgp expression using monoclonal antibodies specific for the mdr-1 and mdr-3 encoded gene products. In B-CLL patients a differential pattern of MDR-3 positive staining was observed; suggesting that MDR-3 positivity may be associated with a more malignant phenotype in B-CLL. This pattern was not observed with MDR-1 positivity. We also observed MDR-3 positivity in an AML stage M5a patient which is the first report of MDR-3 Pgp expression being detected in AML; suggesting that MDR-3 Pgp expression may be limited to particular subtypes of this disease. Results from B-NHL cases were inconclusive with varying expression of MDR-1 and MDR-3 Pgps observed. Work is currently underway to further explain the significance of these findings.

Quality of life in low-income patients with metastatic prostate cancer: divergent and convergent validity of three instruments

Few studies have evaluated Quality Of Life (QOL) among low-income patients with cancer. Information is needed about the feasibility and psychometric characteristics of QOL instruments in these populations. The purpose of this study was to examine the convergent and discriminant relationships between scales of three QOL instruments: European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC), Functional Assessment of Cancer Therapy--General (FACT), and Quality of Life Index (QLI). Participants included 110 men with metastatic prostate cancer of whom 94% were low income and 62% were African-American. Interviewers administered the questionnaires. Cronbach alpha internal consistency reliabilities were 0.57 to 0.90 for the EORTC, 0.65 to 0.86 for the FACT, and 0.63 for the QLI. Convergent validity was supported for the EORTC and FACT scales measuring emotional, physical, and role/functional dimensions (r = 0.54 to 0.72), but not on scales measuring social function (r = 0.12). Divergent validity was supported between dissimilar scales (r = 0.14 to 0.38). Analysis with receiver operating characteristics curves provided empirical support for the EORTC and FACT as multidimensional measures. These findings suggest that, even in busy clinical settings with low literacy patients, interviewer-administered EORTC and FACT QOL instruments can provide valid and reliable information.

The spectrum of mutations in TBX3: Genotype/Phenotype relationship in ulnar-mammary syndrome

Ulnar-mammary syndrome (UMS) is a pleiotropic disorder affecting limb, apocrine-gland, tooth, hair, and genital development. Mutations that disrupt the DNA-binding domain of the T-box gene, TBX3, have been demonstrated to cause UMS. However, the 3' terminus of the open reading frame (ORF) of TBX3 was not identified, and mutations were detected in only two families with UMS. Furthermore, no substantial homology outside the T-box was found among TBX3 and its orthologues. The subsequent cloning of new TBX3 cDNAs allowed us to complete the characterization of TBX3 and to identify alternatively transcribed TBX3 transcripts, including one that interrupts the T-box. The complete ORF of TBX3 is predicted to encode a 723-residue protein, of which 255 amino acids are encoded by newly identified exons. Comparison of other T-box genes to TBX3 indicates regions of substantial homology outside the DNA-binding domain. Novel mutations have been found in all of eight newly reported families with UMS, including five mutations downstream of the region encoding the T-box. This suggests that a domain(s) outside the T-box is highly conserved and important for the function of TBX3. We found no obvious phenotypic differences between those who have missense mutations and those who have deletions or frameshifts.

QOL and outcomes research in prostate cancer patients with low socioeconomic status

The VA Cancer of the Prostate Outcomes Study (VA CaPOS) is collecting quality-of-life (QOL) information from prostate cancer patients, spouses, and physicians at six VA medical centers. Currently, 601 men with prostate cancer are included in the study, most of whom are of low socioeconomic status and over half of whom are African-American. Quality-of-life responses were most favorable for newly diagnosed patients, intermediate for those with stable metastatic disease, and poorest for those with progressive metastatic disease. Patients could not provide reliable estimates of their own preferences for future QOL states but responded reliably to questions phrased as a comparison of the preferences of two hypothetical patients. High out-of-pocket costs for hormonal therapies, lack of health insurance, and a belief that the non-VA system offered poorer services were the most common reasons for patient transferral to the VA system. Satisfaction with medical care was generally high. While African-American patients were more likely to have advanced prostate cancer at diagnosis, after adjustment for differences in health literacy, race was no longer a significant predictor of advanced disease. The VA CaPOS provides useful information on health status and patient satisfaction of VA prostate cancer patients. Long-term evaluations are needed to detect clinically meaningful QOL information as the disease progresses.

Transcriptional regulation of the mouse ferritin H gene. Involvement of p300/CBP adaptor proteins in FER-1 enhancer activity

We previously identified a major enhancer of the mouse ferritin H gene (FER-1) that is central to repression of the ferritin H gene by the adenovirus E1A oncogene (Tsuji, Y., Akebi, N., Lam, T. K., Nakabeppu, Y., Torti, S. V., and Torti, F. M. (1995) Mol. Cell. Biol. 15, 5152-5164). To dissect the molecular mechanism of transcriptional regulation of ferritin H, E1A mutants were tested for their ability to repress FER-1 enhancer activity using cotransfection with ferritin H-chloramphenicol acetyltransferase (CAT) reporter constructs. Here we report that p300/CBP transcriptional adaptor proteins are involved in the regulation of ferritin H transcription through the FER-1 enhancer element. Thus, E1A mutants that failed to bind p300/CBP lost the ability to repress FER-1, whereas mutants of E1A that abrogated its interaction with Rb, p107, or p130 were fully functional in transcriptional repression. Transfection with E1A did not affect endogenous p300/CBP levels, suggesting that repression of FER-1 by E1A is not due to repression of p300/CBP synthesis, but to E1A and p300/CBP interaction. In addition, we have demonstrated that transfection of a p300 expression plasmid significantly activated ferritin H-CAT containing the FER-1 enhancer, but had a marginal effect on ferritin H-CAT with FER-1 deleted. Furthermore, both wild-type p300 and a p300 mutant that failed to bind E1A but retained an adaptor function restored FER-1 enhancer activity repressed by E1A. Sodium butyrate, an inhibitor of histone deacetylase, mimicked p300/CBP function in activation of ferritin H-CAT and elevation of endogenous ferritin H mRNA, suggesting that the histone acetyltransferase activity of p300/CBP or its associated proteins may contribute to the activation of ferritin H transcription. Recruitment of these broadly active transcriptional adaptor proteins for ferritin H synthesis may represent an important mechanism by which changes in iron metabolism are coordinated with other cellular responses mediated by p300/CBP.

A new monoclonal antibody that specifically recognises the MDR-3-encoded gene product

The MDR-3-encoded P-glycoprotein (Pgp) is highly expressed in liver and is thought to function as a hepatic transporter of phospholipids into bile. However its role, if any, in other tissues remains undefined. Although transfection experiments have indicated that it may be unable to confer drug resistance, there is evidence that it may be involved in drug resistance in certain B-cell leukaemias. To date, most work on clinical samples has been performed at the mRNA level; limited work has been performed using polyclonal antibodies raised to MDR-3 and mdr-2 (the murine equivalent of MDR-3). We have generated a new monoclonal antibody, termed 6/1G, which specifically recognises the human MDR-3 gene-encoded product. Antibody 6/1G was produced by in vitro immunisation of spleen cells from BALB/c mice with a synthetic 12-amino acid peptide. Cells from MDR-3 transgenic mice showed consistent membranous staining with antibody 6/1G. Immunoblotting with 6/1G identified a band at 170 kDa on lysates of MDR-3 transgenic cells. Preliminary results with a range of B-cell leukaemias suggest that MDR-3 Pgp positivity may be a marker for a more malignant phenotype in B-CLL. Antibody 6/1G may be useful in defining a role for MDR-3 in malignancy and drug resistance, as well as in certain liver diseases such as progressive familial intracholeostasis.

An inter-regional comparison: fatal crashes in the southeastern and non-southeastern United States: preliminary findings

The southeastern United States, particularly those states representing the National Highway Traffic Safety Administration's and Federal Highway Administration's Region IV, have consistently had among the highest number of fatal crashes and fatal crash rates compared to the other five regions in the US. These states--Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, and Tennessee, are suspected of sharing traits in common that lead to their systematically poor crash record. Inter-regional and intra-regional comparisons, such as the comparison between southeastern and non-southeastern states, raises interesting and challenging research questions that are applicable to similar comparisons. First, is there a sound practical and theoretical justification supporting an inter-regional comparison framework? Second, is there a way to construct a meaningful statistical hypothesis and test to determine whether one region, which is comprised of numerous entities, suffers from a characteristically better or worse crash record? This paper addresses each of these questions. After providing a brief summary of the Southeast's safety record, we discuss the issues pro and con surrounding inter-regional comparisons, illustrating the statistical strategy for such an analysis approach. Then, a simple generalizable statistical procedure is used for testing the hypothesis that southeastern states have a poorer crash record than non-southeastern states. Finally, we explore possible relationships between safety belt use, roadway functional class, vehicle miles of travel, and driver age on fatal crash occurrence. The data used in the analyses are from the Fatal Analysis Reporting System (FARS), primarily data compiled for 1995. The analysis suggests that regional differences in fatal crashes may indeed exist, that these differences are related in part to seat-belt use, VMT by functional classification, and speed limit differences, and that more detailed studies are needed to quantify the effect of these and other factors. The approach developed here lends insight as to where future in-depth studies may reveal causal factors of fatal crashes, and illustrates the relative safety performance records of US regions.

Transactivation of the human cdc2 promoter by adenovirus E1A in cycling cells is mediated by induction of a 110-kDa CCAAT-box-binding factor

Cyclin-dependent protein kinases (Cdks) are key regulatory proteins of the eukaryotic cell cycle. Cdc2 is expressed in late G1/S phase and functions in the G2 to M phase transition. Adenovirus E1A proteins are known to induce the expression of p34cdc2 and DNA synthesis in normal quiescent cells. In this study, mutational analysis of the human cdc2 promoter revealed that transactivation of the promoter by the E1A proteins in cycling cells is mediated through the two CCAAT box binding motifs. A 110-kDa protein (CBF/cdc2) was identified in nuclear extracts from monkey kidney (CV-1) cells stably expressing E1A as well as from adenovirus-transformed human 293 cells. Further, we show that this EIA-inducible CBF/cdc2 is related to the CBF which was shown to activate the heat shock protein 70 promoter. Analyses of the functional domain(s) of E1A required for the induction of the CBF and transactivation of the cdc2 promoter in these conditions revealed that E1A mutants which were defective in binding the pRB family of proteins or the cellular p300 protein were still active in assays measuring the induction of the CBF and transactivation of the cdc2 promoter, albeit with reduced efficiencies. But the E1A mutant which lost both functional domains was inactive in these assays. These results suggest that E1A has redundant functional domains for the induction of the 110-kDa CBF and activation of human cdc2 gene expression.

Monoclonal antibodies raised to paraffin wax embedded archival tissue; feasibility study of their potential to detect novel antigenic markers

A study to determine the feasibility of using archival paraffin wax embedded tissue to generate monoclonal antibodies is described. Specifically, monoclonal antibodies were raised to paraffin wax embedded normal human kidney tissue to test the possibility of producing antibodies to such tissue samples prior to attempting generation of antibodies to valuable archival tissue. Multiple sections (10 x 5 microm) were pooled and dewaxed as for immunohistochemical procedures and combined with Freund's adjuvant for immunization of BALB/c mice in vivo. Immunized spleen cells were fused with SP2 myeloma cells and subsequent clones screened on paraffin wax embedded normal human kidney sections, a range of cell lines and normal mouse tissue. Supernatants from 11 wells (from a total of 90 wells screened) showed different staining patterns on sections of paraffin wax embedded kidney. One clone, 1/11C, (isotype IgG1) which exhibited strong staining on all kidney tubules by immunohistochemical studies (glomeruli interstitium and vessels were unstained) and identified a band at 52 kDa on immunoblots of dewaxed kidney tissue (as used for immunogen) was chosen for further characterization. Immunoblotting of five mammalian cell lines showed differential expression of this 52 kDa band (distinct expression on 3/5, weak expression on 2/5 cell lines) whereas, all cell lines displayed a band at 44 kDa and a third band at 70 kDa was observed on 2/5 cell lines. In mouse tissue extracts, the 52 kDa band was identified in kidney tissue only (not in the lung, liver or spleen) with the 44 kDa and 70 kDa bands weakly expressed in all tissues. This preliminary investigation of a novel approach to identifying possible new antigenic markers or producing monoclonal antibodies which react better to known antigens on sections of paraffin wax embedded tissue showed that this method is feasible. The need to have a comprehensive screening system in place and the ability to identify potentially useful clones after the initial screening is paramount due to the relative scarcity of screening material (archival tissue sections) and the tedious nature of the screening method.

Abnormal bone remodelling in inflammatory arthritis

Osteopenia is responsible for substantial comorbidity in patients suffering from rheumatoid arthritis and is an important factor in the surgical management of joint disease. In animal models of bone loss stimulated by inflammatory arthritis, increased bone remodelling and altered microstructure of bone have been documented. The subchondral bone plate near the joint surface is narrow and perforated by vascular inflammatory invasion, and in the shaft the thin cortices are weakened by giant resorption defects. Biomechanical tests and a mathematical model of bone strength suggest that cortical defects, much larger than those found in normal osteonal remodelling, are principally responsible for the experimentally observed loss of strength. Similarly, these defects may explain the increased femoral fracture risk in rheumatoid arthritis. The osteoclast, the cell resorbing bone, is demonstrated in increased number and activity in rheumatoid arthritis and in animal models. Bisphosphonates, drugs that inhibit osteoclast function, have been shown experimentally to reduce both focal and generalized osteopenia and to prevent loss of bone strength. Bisphosphonates also protect articular cartilage from damage characteristic of inflammatory arthritis. The mechanism of chondroprotection may be prevention of subchondral bone resorption by the osteoclast and also an altered distribution of bone marrow cells. Thus, bisphosphonates, currently in clinical use for other bone metabolic diseases, appear to have potential as prophylaxis and treatment for osteopenia and joint damage in inflammatory arthritis.

Differential regulation of p53-dependent and -independent proliferating cell nuclear antigen gene transcription by 12 S E1A oncoprotein requires CBP

The tumor suppressor protein p53 and the adenoviral 12 S E1A oncoprotein are both known to elicit their biological effects mainly by regulating the transcription of important cellular genes. The human proliferating cell nuclear antigen (PCNA) gene is a transcriptional target of both p53 and E1A. We have analyzed the effects of p53 and 12 S E1A, separately as well as together, on PCNA gene transcription. Our results showed that whereas both p53 and 12 S E1A separately activated PCNA transcription, 12 S E1A repressed p53-mediated transcriptional activation. Thus, 12 S E1A uses a dual strategy of transcriptional activation and repression to take control of the cellular PCNA gene regulation. The cyclic AMP-response element in the PCNA core promoter, besides being crucial for basal transcription, synergizes with p53 to activate transcription. The cyclic AMP response element-binding protein (CREB)-binding protein (CBP) is an essential component of both the transcriptional activation and repression by E1A. Our data demonstrate for the first time that E1A can modulate CBP function to activate PCNA transcription, while at the same time repressing p53-mediated activation by disrupting CBP interaction with p53, thereby uncoupling PCNA transcription from the regulatory effects of p53.

p300/CREB binding protein-related protein p270 is a component of mammalian SWI/SNF complexes

p300 and the closely related CREB binding protein (CBP) are transcriptional adaptors that are present in intracellular complexes with TATA binding protein (TBP) and bind to upstream activators including p53 and nuclear hormone receptors. They have intrinsic and associated histone acetyltransferase activity, suggesting that chromatin modification is an essential part of their role in regulating transcription. Detailed characterization of a panel of antibodies raised against p300/CBP has revealed the existence of a 270-kDa cellular protein, p270, distinct from p300 and CBP but sharing at least two independent epitopes with p300. The subset of p300/CBP-derived antibodies that cross-reacts with p270 consistently coprecipitates a series a cellular proteins with relative molecular masses ranging from 44 to 190 kDa. Purification and analysis of various proteins in this group reveals that they are components of the human SWI/SNF complex and that p270 is an integral member of this complex.

MDR1 expression is associated with adverse survival in melanoma of the uveal tract

Metastatic uveal melanoma is profoundly chemoresistant and has a very poor outcome. We have previously shown that the MDR1 gene and its gene product P-glycoprotein (P-gp), which are known to cause drug resistance in cancer cells, are expressed in ocular melanoma. Overexpression of MDR1 has been associated with a poor survival in some tumor types treated by chemotherapy and in some untreated tumours. To assess whether MDR1 expression is of prognostic value in uveal melanoma, we evaluated the expression of MDR1 by immunohistochemistry in 108 cases. Three semiquantitative grades were used to evaluate positive staining. We detected MDR1 expression in 80% of cases; 28% showed grade I staining; 30%, grade II staining; and 22%, grade III staining. There was a statistically significant association (P=.004) between MDR1 expression by tumor cells and shorter survival times (n=96), which was most striking at grade III levels of expression. Multivariate analysis showed that MDR1 expression is an independent prognostic indicator of poor survival. We conclude that (1) MDR1 may be involved in chemoresistance and tumor propagation in primary uveal melanoma, and (2) increasing levels of expression are prognostically significant and may prove a useful marker of tumor invasiveness, independent of established prognostic factors.

A new form of complicated hereditary spastic paraplegia with cataracts, atretic ear canals and hypopigmentation

A 16-year-old Hispanic boy born of consanguineous parents is described as having a history of cataracts, progressive lower-extremity spasticity and atrophy starting at 4 years of age, atretic ear canals with hearing dysfunction and diffuse patchy cutaneous hypopigmented areas. Clinical examination showed the typical signs of spastic paraplegia with increased tone, hyperreflexia, muscle atrophy and contractures. Sensation, autonomic and cerebellar functions were not disturbed. Neuroimaging studies were normal. Laboratory findings did not support a diagnosis of metabolic disturbance or infectious disease. This is considered a new form of complicated hereditary spastic paraplegia (HSP), transmitted presumably in an autosomal recessive pattern.

Relationship between alkaline phosphatase levels, osteopontin expression, and mineralization in differentiating MC3T3-E1 osteoblasts

We are using viral oncogene probes to study the pathways by which osteoblast-specific gene expression is induced in ascorbic acid-treated MC3T3-E1 cells. The 12S product of the adenovirus E1A gene binds directly to key cellular regulators and, as a result, represses tissue specific gene expression and blocks differentiation in a wide variety of cell types. The main cellular targets of the E1A 12S product are the pRB family and p300/CBP family. The p300 family appears to be the primary target for E1A-mediated repression of tissue-specific gene expression in a variety of cell types. We have generated MC3T3-E1 cell lines that stably express either the wild-type 12S product or a mutant that targets p300/CBP, but not the pRB family. Using these constructs to dissect osteoblast differentiation, we found that targeting of p300/CBP appears to be sufficient to repress alkaline phosphatase expression, although a low but functional level of expression can be maintained if the pRB family is not targeted as well. Induction of alkaline phosphatase expression and activity can be dissociated from expression of late-stage markers such as osteocalcin and osteopontin. Surprisingly, cell lines exhibiting severe repression of alkaline phosphatase activity differentiate to a mineral-secreting phenotype much like normal MC3T3-E1 cells. Osteopontin induction is dependent on at least a minimal level of alkaline phosphatase activity, although it is not dependent on induction of alkaline phosphatase at the RNA level. If alkaline phosphatase is supplied exogenously, osteopontin expression can be induced in conditions in which endogenous alkaline phosphatase is severely repressed.

CREB-binding protein and p300/CBP-associated factor are transcriptional coactivators of the p53 tumor suppressor protein

The structurally related transcriptional coactivators p300 and CBP possess histone acetyltransferase activity and associate with P/CAF, which is also a histone acetyltransferase. CBP and p300 have properties of tumor suppressor proteins; their interaction with P/CAF is disrupted by the adenoviral E1A oncoprotein, and the genes encoding CBP and p300 are mutated in human cancer. We observed a physical interaction between the transactivation domain of the p53 tumor suppressor protein and CBP. Furthermore, CBP and P/CAF enhanced the ability of p53 to activate expression of the endogenous p21(cip1/waf1) gene, whereas E1A and dominant negative CBP mutants suppressed p53-dependent p21(cip1/waf1) expression. These studies link two tumor suppressor families and provide a framework for understanding the molecular mechanism by which p53 activates transcription.

Monoclonal antibody NM11 recognizes a C-terminal epitope shared by p300 and CBP

The epitope recognized by the monoclonal antibody NM11, previously shown to recognize both CBP and p300, has been mapped here to the C-terminal third of p300 and CBP by Western analysis of p300 and CBP prokaryotic fusion proteins. More precise epitope mapping, carried out by screening a plasmid expression library derived from small randomly generated CBP cDNA fragments localizes the NM11 epitope to a 21 amino acid stretch spanning amino acids 2071-2091 near the CBP C-terminus. CBP and p300 differ by three noncontiguous residues within this 21 amino acid region, a difference that does not detectably affect the reactivity of NM11.

A new mdr-1 encoded P-170 specific monoclonal antibody: (6/1C) on paraffin wax embedded tissue without pretreatment of sections

AIMS

The generation and characterisation of a monoclonal antibody that specifically recognises the mdr-1 encoded protein, P-glycoprotein (P-170), on routinely processed formalin fixed, paraffin wax embedded tissue sections.

METHODS

The monoclonal antibody, designated 6/1C, was produced following a combination of in vivo and in vitro immunisation regimens in Balb/c mice with a synthetic 12 amino acid peptide that corresponds to amino acids 21-32 (believed to be intracellularly located) of P-170 and has insignificant homology with the mdr-3 encoded P-170. Antibody 6/1C was characterised by western blotting and immunocytochemistry on cytospins of paired multidrug resistant or sensitive cell lines, including mdr-1 and mdr-3 transfected cells, and by immunohistochemistry on normal and malignant formalin fixed paraffin wax embedded tissue sections.

RESULTS

Antibody 6/1C showed a single band at 170 kDa on western blots of multidrug resistant cell lysates and mdr-1 transfected cell lysates that was absent on similar preparations of drug sensitive cells and mdr-3 transfected cells. Immunocytochemical studies on cytospins of multidrug resistant cells and mdr-1 transfected cells revealed strong inner plasma membrane/cytoplasmic staining. Staining was negligible on drug sensitive cells and cells transfected with the mdr-3 gene. Immunohistochemical studies on formalin fixed, paraffin wax embedded normal adult kidney, liver, and breast tissue and a range of fetal tissues exhibited staining patterns of a variety of secretory surfaces consistent with documented mdr-1 specific staining. Specific staining of malignant cells in similarly treated sections of breast tumours was seen also with antibody 6/1C. Staining on paraffin wax embedded tissue with this antibody did not require any pretreatment of tissue sections.

CONCLUSIONS

This new monoclonal antibody, chosen for its specificity with the mdr-1 encoded P-170 and its reactivity on routinely fixed paraffin wax embedded tissue samples without pretreatment, appears to be useful for the investigation of P-170 in archival material. It is especially useful for retrospective studies on pretreatment and post-treatment tissue sections, and could help establish when and how rapidly mdr-1 associated drug resistance develops during chemotherapeutic regimens. Immunohistochemical assessment of P-170 expression in many cancers has potential for diagnostic purposes and may influence the choice of chemotherapeutic drugs used in the treatment of refractory tumours.

The multidrug-resistant human lung tumour cell line, DLKP-A10, expresses novel drug accumulation and sequestration systems

Drug accumulation studies with the anticancer agents adriamycin and vincristine were carried out on the MDR variant of the human lung cell lines DLKP, DLKP-A10 which overexpresses the MDR associated P-glycoprotein efflux pump. Reduced cellular accumulation of both agents was observed in the resistant variant. The subsequent addition of verapamil and cyclosporin A resulted in partial restoration of cellular accumulation of both drugs in the DLKP-A10 resistant variant while complete restoration of cellular drug levels was observed in the SKMES-1/ADR cell line. These results suggested that the accumulation defect observed in the SKMES-1/ADR cell line was P-glycoprotein mediated and that accordingly, the cells exhibited characteristics consistent with the classical MDR phenotype. In contrast, while P-glycoprotein also appears to mediate a reduction in cellular drug accumulation in the DLKP-A10 cells, an alternative transport mechanism may also be present. No significant increase in the expression of either the MRP or LRP transport proteins was observed in the resistant cells. Metabolic inhibition by antimycin A (but not sodium azide or 2-deoxy-D-glucose) resulted in complete restoration of drug accumulation suggesting the presence of an alternative energy dependent transport mechanism. Fluorescent microscopy studies indicated different cellular localisation of the drug within the parental and resistant cells despite equivalent intracellular concentrations. These studies also revealed the presence of an ATP-dependent, vesicular sequestration mechanism which may be involved in the reduction of nuclear adriamycin accumulation in the DLKP-A10 cell line. This was indicated by observation of the disruption of cytoplasmic vesicles by antimycin A and also inhibition of cytoplasmic drug sequestration by the carboxylic ionophores, monensin and nigericin, accompanied by increased adriamycin accumulation and redistribution of the drug from the cytoplasm to the nucleus.

Co-expression of MDR-associated markers, including P-170, MRP and LRP and cytoskeletal proteins, in three resistant variants of the human ovarian carcinoma cell line, OAW42

Variants of the human ovarian carcinoma cell line, OAW42, exhibiting low-level intrinsic resistance (OAW42-SR) and drug-induced higher-level resistance (OAW42-A1 & OAW42-A), were studied along with a sensitive clonal population (OAW42-S) which was isolated from OAW42-SR. Expression of the MDR-associated protein P-170, the more recently discovered LRP (lung resistance-related protein) and MRP (multidrug resistance-associated protein), topoisomerase II alpha and beta, GST pi and the cytoskeletal proteins, cytokeratin 8 and vimentin, were studied (using immunocytochemistry and Western blotting techniques) in conjunction with drug (doxorubicin) accumulation and subcellular distribution. Expression of mRNA for P-170, MRP, topoisomerase 11 alpha and beta and GST pi was studied using RT-PCR (reverse transcriptase polymerase chain reaction). Results indicate differential co-expression of four MDR-associated parameters (P-170, MRP, LRP and reduced topoisomerase II alpha and beta) in the OAW42-SR and OAW42-A1 variants, whereas resistance in the OAW42-A variant appeared to be mainly P-170 mediated. Comparable amounts of MRP and greater amounts of LRP were detected in the OAW42-S cells compared to the OAW42-SR variant (which showed increased resistance compared to the OAW42-S cells), but all cell lines expressed similar low-level amounts of MRP mRNA (by RT-PCR). GST pi levels did not differ markedly between variants. Increased levels of the cytoskeletal proteins were observed with increasing levels of resistance. The relative resistance of the variants, OAW42-SR and OAW42-A1, compared with OAW42-S was seen to change during increased serial passaging of the cells. There was greater drug accumulation by the sensitive OAW42-S cell line compared with that of the resistant variants, particularly the most highly resistant OAW42-A cells. Both verapamil and cyclosporin A effectively restored the accumulation defects seen in the resistant variants, cyclosporin A being the more effective of the two. Sub-cellular location of drug was predominantly in the nucleus with maximum levels seen in the sensitive OAW42-S variant and minimum levels in the most resistant OAW42-A clone.

Characterization of monoclonal antibodies raised against p300: both p300 and CBP are present in intracellular TBP complexes

The amino terminus of the adenovirus E1A protein is involved in E1A transforming functions, repression of tissue-specific gene expression, and E1A-mediated enhancer repression. These N-terminal functions are associated with the ability of this region of E1A to bind to p300 and CBP, two closely related cellular proteins thought to function as transcriptional adaptor molecules. Here we describe the characterization of a panel of 11 monoclonal antibodies raised against E1A-affinity-purified 300-kDa proteins. The panel can be divided into two groups based on immunoprecipitation patterns. The first group consists of five p300/CBP-cross-reactive and two p300-specific monoclonal antibodies, all of which immunoprecipitate p300 and/or CBP without associated cellular proteins. In contrast, the second group immunoprecipitates p300 or both p300 and CBP in association with a complex of at least seven other cellular proteins. Taking advantage of the specificities of these monoclonal antibodies, we have identified both p300 and CBP in in vivo complexes with TBP, a finding consistent with a role for both p300 and CBP in promoting interactions between upstream promoter elements and the basal transcription apparatus.

A potential role for cell cycle control proteins in regulation of the cyclic adenosine 5'-monophosphate-responsive glycoprotein hormone alpha subunit gene

The production of chorionic gonadotropin is coupled to the differentiation of the placenta. Expression of the alpha subunit of chorionic gonadotropin [glycoprotein hormone alpha (GPH-alpha)] is also known to be stimulated by treatment of placental cells with either cAMP or DNA synthesis inhibitors. Given these features, we used adenovirus E1A as a molecular probe to investigate a potential role for cell cycle regulatory proteins and kinases in the regulation of GPH-alpha expression. The E1A protein contains well-characterized domains that interact with a variety of cell cycle regulatory proteins. The E1A conserved regions 1 and 2 bind proteins that regulate cell cycle progression, including pRB, p107, and p130. The amino-terminal region of E1A binds several high molecular weight proteins and inhibits the transcriptional coactivator function of p300 and the homologous cAMP response element (CRE)-binding protein. We found that coexpression of E1A13S activated the GPH-alpha promoter, whereas E1A12S caused marked repression. Deletion mutants and point mutations revealed that repression by E1A12S required the CRE of the GPH-alpha promoter. Several distinct domains in E1A12S were necessary for maximal repression. A mutation of the E1A amino terminus (RG2), which inhibits binding of p300 and related high molecular weight proteins, reduced 12S repression by 40%. Mutation of the pocket protein-binding domains reduced repression by 20%, and mutations of both domains reduced repression by 80%. Overexpression of p300 or the pocket proteins (pRB, p130, and p107) induced GPH-alpha promoter activity 2-4-fold. Because the E1A amino terminus and pocket protein-binding domains together induce p34cdc2 kinase activity, the effect of p34cdc2 kinase expression on GPH-alpha activity was also assessed. Coexpression of p34cdc2 kinase or the activating p34cdc2 kinase mutant (T14AY15F) inhibited GPH-alpha promoter activity and acted through the CRE. We conclude that the GPH-alpha gene CRE is subject to regulation by cell cycle regulatory kinases and proteins.

Subchronic toxicity of 4-vinylcyclohexene in rats and mice by inhalation exposure

This study was conducted to evaluate the subchronic toxicity of 4-vinylcyclohexene (VCH). Male and female Sprague-Dawley rats and B6C3F1 mice were exposed by inhalation to VCH 6 hr/day, 5 days/week for 13 weeks. Rats were exposed to 0, 250, 1000, or 1500 ppm, and mice were exposed to 0, 50, 250, or 1000 ppm. In addition, another group of rats and mice was exposed to 1000 ppm butadiene so that a comparison could be made between the two compounds. Exposure to 1000 ppm VCH resulted in deaths of all male mice and 5/10 female mice on Test Days 11 or 12. Three additional female mice exposed to 1000 ppm VCH died prior to study completion. The most notable compound-related clinical sign was lethargy observed in the 1500 ppm VCH-exposed rats and 1000 ppm VCH-exposed mice. Male rats exposed to 1500 ppm VCH had significantly lower body weights compared to controls, and male and female rats in the 1500 ppm group had significantly lower body weight gains. None of the VCH-exposed animals or butadiene-exposed rats showed any compound-related hematological effects. However, mice exposed to 1000 ppm butadiene exhibited mild macrocytic anemia. Clinical chemistry evaluation and urinalysis showed no compound-related effects in rats exposed to either VCH or butadiene. Male and female rats exposed to 1000 or 1500 ppm VCH or 1000 ppm butadiene had increased absolute and/or relative liver weights, and male rats in these same exposure groups had increased relative kidney weights. Microscopically, increased accumulation of hyaline droplets was observed in the kidneys of male rats from all VCH exposure groups. Although compound-related, the droplets were not accompanied by cytotoxicity. In mice, the most notable adverse histopathological effect was ovarian atrophy in females exposed to 1000 ppm VCH or 1000 ppm butadiene. The atrophy was slightly more severe in the VCH-exposed females than in the butadiene-exposed females. There were no other compound-related pathological effects in male or female mice exposed to VCH. Additionally, butadiene-exposed male mice had decreased testicular weights, accompanied by slight testicular degeneration and atrophy. For VCH exposure, the no-observed-adverse-effect-level is 1000 ppm for rats based on lethargy and lowered body weights and 250 ppm for mice based on mortality and ovarian atrophy.

Behavior of a novel monoclonal antibody for investigation of ovarian cancer and with possible involvement in multiple drug resistance

Monoclonal antibodies (MAbs) were raised to an ovarian cancer cell line, OAW42, derived from a patient with a histology of serous cystadenocarcinoma of the ovary, in an attempt to identify novel antigens with a possible role in cancer medicine. One antibody P1H10, subclass IgG1, with a high titer was isolated and shown to recognize an antigen of 48 kDa. Enzyme-linked immunosorbent assay and immunocytochemical studies showed the presence of the target antigen in a number of carcinoma cell lines, including lung and breast, and in two out of three frozen breast tissue specimens. The antigen was not detected in normal human lymphocytes and there was minimal binding of the antibody to normal buccal cells. The antigen was not secreted by the OAW42 or the HepG2 cell lines and was not detected in the sera of a number of ovarian cancer patients. Indirect immunofluorescence studies confirmed the localization of the antigen to be intracellular. The binding of the antibody P1H10 to a number of multidrug resistant variants of the OAW42 cell line showed that the presence and the localization of the antigen in the drug-sensitive parental line and resistant variant cell lines was distinctly different and varied with the degree of drug resistance. The relative specificity of the antibody suggests it may be a possible diagnostic agent in human cancer. A possible role of the antigen in multiple drug resistance (MDR) is also suggested.