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D Theodorescu

Publications and source records attributed to D Theodorescu.

71 records · Page 4Linked to original sources
PubMed1992

TGF-beta 1 is an autocrine-negative growth regulator of human colon carcinoma FET cells in vivo as revealed by transfection of an antisense expression vector.

Transforming growth factor-beta 1 (TGF-beta 1) has previously been implicated as a potential negative autocrine or paracrine growth regulator of certain cell types (Arteaga, C. L., R. J. Coffey, Jr., T. C. Dugger, C. M. McCutchen, H. L. Moses, and R. M. Lyons. 1990. Cell Growth & Differ. 1:367-374; Hafez, M. M., D. Infante, S. Winawer, and E. Friedman. 1990. Cell Growth & Differ. 1:617-626; Glick, A. B., K. C. Flanders, D. Danielpour, S. H. Yuspa, and M. B. Sporn. 1989. Cell Regulation. 1:87-97). This is based mainly on experiments assessing the effects of exogenous TGF-beta 1 or neutralizing antibodies to TGF-beta 1 on normal or tumor cell proliferation in vitro. However, direct evidence demonstrating such a negative regulation of tumor cell growth in vivo is still lacking. To overcome this problem we have constructed and used an antisense expression vector for TGF-beta 1 as a means of regulating endogenous TGF-beta 1 expression in tumor cells. Antisense-transfected FET human colon carcinoma cells showed a fivefold reduction in TGF-beta 1 mRNA and 15-fold reduction in TGF-beta 1 secretion. Antisense mRNA was detected in transfected cells by an RNase protection assay. Compared to control cells, cultured antisense-transfected cells showed a reduction in lag phase time rather than a change in doubling time. Cloning efficiencies of transfected cells were four times greater than control cells in anchorage-independent assays. Control cells did not form tumors at 5 x 10(5) in athymic nude mice. Antisense-transfected cells formed tumors in 40% of animals injected. At higher inocula (1 x 10(6) cells) antisense-transfected cells formed tumors in 100% of animals injected, but control cells still failed to form tumors. These results show that TGF-beta 1 acts as a negative growth regulator of human colon carcinoma cells in vivo as well as in vitro. Acquisition of partial or full resistance to such inhibitory effects may therefore contribute to tumor development and progression.

Animals↗
PubMed1992

The intestinoprostatic capsule anastomosis: functional and anatomic results in a canine model.

Because of its potential application to intestinal bladder reconstructions, the authors studied the functional and anatomic results of a modification of the Camey procedure. In this modification the enteric bladder replacement is sutured to the periphery of the prostatic capsule after the inner two-thirds of the prostate gland have been removed. In eight dogs postoperative functional studies revealed that all were continent and potent. Autopsy examination of the area of the intestinoprostatic anastomosis revealed that the prostatic fossa was lined by a transitional epithelial layer originating from the urethral stump and not by intestinal mucosa as might be expected. The results indicated that this modification is simpler technically than the original procedure, that it shortens the operating time and that it gives excellent functional results. If used in the context of bladder cancer, however, the procedure should be undertaken only in the presence of negative biopsies and brushings of the urethra before surgery, because the transitional epithelium lining the prostatic fossa represents a new area at risk later malignant transformation. Moreover, because of the potential importance of the area of prostatic fossa resurfaced postoperatively by urothelium, even patients with normal preoperative urethral biopsies and brushings who undergo such a procedure require careful follow-up with endoscopic examination, urethral biopsy and brushings and cytologic examination of the urine.

Anastomosis, Surgical↗
PubMed1991

Ha-ras induction of the invasive phenotype results in up-regulation of epidermal growth factor receptors and altered responsiveness to epidermal growth factor in human papillary transitional cell carcinoma cells.

Recent studies have shown that orthotopic (transurethral) transplantation of human bladder cancer cell lines into nude mice permits tumor growth that more accurately reflects their clinical malignant status in the original host. We have previously demonstrated that transfection and overexpression of normal or mutated c-Ha-ras genes into a noninvasive human papillary transitional cell carcinoma cell line confer upon these cells an invasive phenotype in vivo with behavior remarkably similar to the clinical behavior of high grade bladder carcinomas. Since elevated expression levels of the epidermal growth factor receptor (EGF-R), in addition to that of c-Ha-ras, have been correlated with transitional cell carcinoma progression, we sought to determine whether up-regulation of the EGF-R had occurred in the invasive high ras expressors and if so, what functional significance this might have. Our results show that invasive cell lines which overexpress the c-Ha-ras gene also have increased epidermal EGF-R expression. This was found to occur at both the protein and mRNA levels, and analysis of the EGF-R promoter/enhancer sequences has revealed a putative AP-1 site which may possibly enhancer sequences has revealed a putative AP-1 site which may possibly serve as a ras response element. In addition, we found that the cells overexpressing the EGF-R had acquired a positive sensitivity to the stimulatory mitogenic effects of EGF. Hence, the results obtained suggest a role for either a normal or a mutated overexpressing Ha-ras in up-regulating the surface EGF-R, possibly through an AP-1 site during human bladder carcinoma progression; they also highlight the potential that EGF may have in cooperating with this EGF-R up-regulation to help mediate enhanced tumor growth.

Blotting, Northern↗
PubMed1991

Fibroblast cell interactions with human melanoma cells affect tumor cell growth as a function of tumor progression.

It is known from a variety of experimental systems that the ability of tumor cells to grow locally and metastasize can be affected by the presence of adjacent normal tissues and cells, particularly mesenchymally derived stromal cells such as fibroblasts. However, the comparative influence of such normal cell-tumor cell interactions on tumor behavior has not been thoroughly investigated from the perspective of different stages of tumor progression. To address this question we assessed the influence of normal dermal fibroblasts on the growth of human melanoma cells obtained from different stages of tumor progression. We found that the in vitro growth of most (4 out of 5) melanoma cell lines derived from early-stage radial growth phase or vertical growth phase metastatically incompetent primary lesions is repressed by coculture with normal dermal fibroblasts, suggesting that negative homeostatic growth controls are still operative on melanoma cells from early stages of disease. On the other hand, 9 out of 11 melanoma cell lines derived from advanced metastatically competent vertical growth phase primary lesions, or from distant metastases, were found to be consistently stimulated to grow in the presence of dermal fibroblasts. Evidence was obtained to show that this discriminatory fibroblastic influence is mediated by soluble inhibitory and stimulatory growth factor(s). Taken together, these results indicate that fibroblast-derived signals can have antithetical growth effects on metastatic versus metastatically incompetent tumor subpopulations. This resultant conversion in responsiveness to host tissue environmental factors may confer upon small numbers of metastatically competent cells a growth advantage, allowing them to escape local growth constraints both in the primary tumor site and at distant ectopic tissue sites.

Adipose Tissue↗
PubMed1991

Dominance of metastatically competent cells in primary murine breast neoplasms is necessary for distant metastatic spread.

We have previously shown, using tumor cell populations genetically tagged by random integrations of plasmid DNA, that metastatically-competent clonal cell variants have a strong growth advantage within primary tumors over their non-metastatic counterparts. As a result, primary tumors can become overgrown by the progeny of such cells, a process referred to as "clonal dominance" of primary tumors by metastatically-competent cells. Because of the well-known "metastatic inefficiency" of the multi-step cascade process of spread and growth, clonal dominance within primary tumors may be necessary for distant metastatic spread or increase the probability of its occurrence. To examine this hypothesis mice were inoculated s.c. with mixture of non-metastatic and genetically tagged, metastatically-competent mouse mammary carcinoma cells in defined ratios, but always containing an excess of the unmarked non-metastatic population. Progressive overgrowth of the metastatic subpopulation was monitored as a function of time by Southern analysis of DNA obtained from mixed primary tumors. This allowed us to evaluate the effects that surgical removal of the primary tumor had before, during and after effective clonal dominance, and what influence this had on the subsequent formation of distant metastases. Surgical removal of primary tumors before metastatic clonal dominance resulted in a low (0.25%) frequency of lung metastases, whereas removal just 1 or 2 weeks later during or after clonal dominance was achieved resulted in a high (75-100%) frequency of such metastases. Our results support the hypothesis that dominance of primary tumors by metastatically competent cells may be necessary for distant metastatic spread, and also suggest that clonal interactions play a significant role in modulating the metastatic ability of tumor cells in vivo.

Adenocarcinoma↗
PubMed1991

Reduction of TGF-beta activity abrogates growth promoting tumor cell-cell interactions in vivo.

We have shown in previous studies that metastatically-competent variant subpopulations (B5, C1) derived from a non-metastatic murine mammary adenocarcinoma (SP1) have a pronounced growth advantage over their non-metastatic tumor cell counterparts in primary tumors. As a result, primary tumors can be progressively overgrown by cells having the competence to spread elsewhere in the body. This occurs despite any evidence to indicate an intrinsic in vivo growth rate advantage of the metastatic cells when grown as isolated populations. This suggested that cell-cell interactions between metastatic and non-metastatic tumor populations may be involved in the metastatic cell growth dominance process. Evidence was therefore sought for growth factors released by SP1 cells which could preferentially stimulate the B5 or C1 variants and thereby mediate this cell-cell interaction process. We found that cocultures of SP1 and C1 or B5 cells with irradiated C1, B5, or SP1 "feeder" cells showed significant stimulation of C1 and B5 by SP1 "feeder" cells. Cell growth stimulation in response to EGF, TGF-alpha, TGF-beta 1, bFGF, PDGF, NGF, IGF-1, or IGF-2 demonstrated that only TGF-beta 1 could duplicate this effect. A repeat of the coculture experiment in the presence of specific neutralizing anti-TGF-beta antibodies was therefore undertaken and this was found to markedly reduce the stimulation of C1 or B5 cells by irradiated SP1 cells. Conditioned media from the SP1 and C1 cell lines was quantitated for TGF-beta activity and contained 4.5 ng/ml and 2.0 ng/ml, respectively. However, the majority of the TGF-beta released by SP1 cells was found to be spontaneously active, whereas 70% of the TGF-beta released by C1 cells was in its latent form. Scatchard analysis revealed approximately four times the number of TGF-beta receptors, of similar type and affinity, present on C1 as compared with SP1 cells. The in vitro results support the hypothesis that active TGF-beta released by SP1 cells may stimulate the proliferation of metastatic variant cells in a paracrine like fashion. In vivo evidence for this was obtained by showing that coinjection of irradiated SP1 cells could selectively stimulate tumor growth of viable C1 cells and this effect was markedly diminished by neutralizing polyclonal anti-TGF-beta antibodies. Taken together, the results suggest a novel role for TGF-beta in clonal evolution of malignant tumor growth and as a molecular mediator of tumor cell-tumor cell interactions involved in facilitating tumor progression.

Adenocarcinoma↗
PubMed1991

Importance of orthotopic transplantation procedures in assessing the effects of transfected genes on human tumor growth and metastasis.

Assessment of the function of putative dominantly-acting oncogenes or recessive tumor-suppressor genes in human tumor development and progression must ultimately involve xenografting experiments using immune deficient animals such as nude mice. Most human tumor xenograft experiments have employed conventional subcutaneous injection procedures. However, despite the simplicity of this procedure, it poses some serious potential drawbacks as most types of human tumor will not readily grow or metastasize from a subcutaneous ('ectopic') site of injection. In contrast, 'orthotopic' injection procedures will often enhance the tumorigenic and/or metastatic ability of tumor cell populations. An example of this is summarized in the context of human malignant melanoma where the effects of subcutaneous versus subdermal injection are compared. Despite the seeming subtle and minor change in injection site, superior growth of human melanomas can be obtained by the latter, orthotopic-like, route of injection. It therefore follows that induction of tumorigenic or metastatic properties in a given human cell population by gene transfection may not be detected if the transfected cells are assayed in vivo only by subcutaneous injection procedures. An example of this is provided by experiments involving transfection of normal or mutated ras genes into a low-grade, well-differentiated human bladder carcinoma cell line, called RT-4. Thus overexpression of normal or mutated (valine 12) c-H-ras resulted in acquisition of a clinical-like invasive phenotype. However, this was clearly seen only if the cells were injected into the bladders (i.e. 'intravesically') of nude mice. In contrast, conventional subcutaneous injection of the high ras expressing transfected RT-4 cell lines did not reveal acquisition of invasive properties: all cell lines grew locally as well-encapsulated tumor masses. It is argued that similar orthotopic injection procedures should be employed when assessing the suppressive effects of various wild-type tumor-suppressor genes on human tumor growth in vivo. Utilization of subcutaneous injection procedures may grossly exaggerate the growth suppressive effects of such genes. This could explain the paradox of why, on the one hand, alterations involving many different genes (including different suppressor genes) appear to be involved in human carcinoma tumorigenesis while on the other hand, complete suppression of tumorigenicity can be caused by transfer of a single wild-type suppressor gene. Such complete suppressions might be observed only after ectopic (usually subcutaneous) injection procedures.

Animals↗
PubMed1991

Chronic adult renal vein thrombosis: two unusual cases and a review of the literature.

A panorama of signs and symptoms from the primary and associated disease processes complicates the clinical picture of chronic adult renal vein thrombosis (RVT). This has made the diagnosis of RVT very challenging. In addition, this entity is often overlooked in differential diagnosis due to the patient's often multiple other problems. Detecting this condition may lead to restoration of renal function compromised by renal vein obstruction and thus be of critical benefit in patients who often have compromise of renal function. Two unusual presentations of chronic RVT are discussed and provide a basis for review of the salient features of aetiology, diagnosis and disease management, providing what is hoped to be useful suggestions in diagnosis and management of this condition.

Aged↗
PubMed1991

Cloning and overexpression of TGF-beta 1 cDNA in a mammary adenocarcinoma: in vitro and in vivo effects.

It has been suggested that transforming growth factor beta (TGF-beta) may be a potential negative autocrine growth regulator of carcinomas including mammary carcinomas. To directly test this hypothesis we have cloned and expressed human TGF-beta 1 cDNA in a murine mammary adenocarcinoma which is normally growth-inhibited by addition of exogenous TGF-beta in vitro. A number of transfectants over-expressing the foreign TGF-beta 1 mRNA were selected and compared to transfectants which did not overexpress the exogenous TGF-beta 1 cDNAS. Cell lines overexpressing the transfected TGF-beta 1 mRNA were found to produce total levels of TGF-beta 7 to 10 fold greater than the parental cells or control transfected clones. However, when levels of active fractions of TGF-beta were compared in cell lines overexpressing TGF-beta 1 to those which did not, no differences were found. This suggests that the activation mechanism is not necessarily induced or altered by increasing levels of latent TGF-beta 1 production in a given tumor cell line. The basal in vitro doubling time of TGF-beta 1 overexpressing clones was identical to the control populations. Similarly, in vivo tumor growth rates after s.c. injection were similar to that of the parental line. Thus the precise role of TGF-beta in mediating either the in vitro or in vivo growth control of a sensitive mammary adenocarcinoma cell line remains unclear. It may be that cellular over-secretion of latent TGF-beta must be coupled with enhanced cellular TGF-beta activation prior to any observed effect on growth rate in vitro or in vivo; this latter event may constitute the "rate-limiting" step of TGF-beta activity on tumor behavior.

Adenocarcinoma↗
PubMed1991

[Metastatic dissemination of cancer cells].

During the natural history of a tumor, cancer cells become more and more aggressive and their increasing malignancy leads usually to the patient's death. The expression of malignant properties by tumor cells is manifested by the occurrence of metastases and is the result of an overexpression of molecules that are normally or barely non expressed by the normal cell progenitors. These molecules can be involved in cell attachment (receptor to the extracellular matrix), in proteolysis (collagenases), in angiogenesis (b FGF), in adhesion to endothelial cells, in resistance to the immune system. The genetic instability of tumor cells favors the amplification, mutation and gene translocation events, resulting in the activation of some genes or/and oncogenes which might direct the expression of the malignant properties. Finally, metastatic cells have been shown to have a growth advantage over non metastatic cells, so that metastatic cell population becomes ultimately numerously dominant in the primary tumor. The current knowledge about the malignant cell properties allow us to begin to understand how a cancer cell becomes metastatic and how the metastatic dissemination is usually an ineluctable process.

Animals↗
PubMed1990

Overexpression of normal and mutated forms of HRAS induces orthotopic bladder invasion in a human transitional cell carcinoma.

Recent studies have shown that orthotopic (transurethral) transplantation of human bladder cancer cell lines into nude mice permits tumor growth that accurately reflects their clinical malignant status in the original host. Thus, such a system allows a unique opportunity to analyze the genetic events involved in the conversion of low-grade bladder cancer, the vast majority of which are curable, to the high-grade life-threatening form of the disease. Since 5-10% of transitional cell carcinomas (TCCs) have been shown to contain a mutated HRAS gene, and protein expression levels of all forms of HRAS have been correlated with TCC progression, we chose to study the contribution of the HRAS oncogene in bladder tumor progression. We evaluated the effects of transfection of normal or mutated HRAS genes into a human TCC, called RT-4, that behaves as a superficial noninvasive papillary tumor after transurethral orthotopic inoculation into athymic nude mice. We found that overexpression of either transfected normal or mutated HRAS genes converted RT-4 cells to express an invasive phenotype remarkably similar in nature to the clinical behavior of high-grade bladder carcinomas. These results suggest a role for overexpressed normal or mutated RAS genes in human bladder carcinoma progression, and highlight the importance of using orthotopic inoculation systems for evaluation of the contribution of oncogenes to malignant tumor progression.

Animals↗
PubMed1990

Thymectomy in juvenile myasthenia gravis.

The long-term results of thymectomy in 24 children with generalized myasthenia gravis are reviewed. Sixteen had complete remission and another seven were improved. This compares favorably with reported spontaneous remission rates of 30%. Because of the low morbidity in recent reports and the possibility that early thymectomy is more beneficial, we recommend thymectomy at the onset of juvenile generalized myasthenia gravis.

Adolescent↗
PubMed1987

Neonatal pharyngoesophageal perforation mimicking esophageal atresia: clues to diagnosis.

Perforation of the newborn child's esophagus or pharynx can mimic esophageal atresia clinically. Fourteen cases of newborn hypopharyngeal or esophageal perforation are presented. In nine cases, esophageal atresia was the initial diagnosis entertained; seven of these on the first day of life. In four others, the diagnosis of a perforated pharynx or esophagus was evident on plain x-ray. Six patients had esophagograms. Two newborns underwent thoracotomies for repair of their initially diagnosed esophageal atresia. Subsequently, esophageal perforation was diagnosed intraoperatively on each and suture repair was undertaken. The 12 remaining neonates were treated nonoperatively. There were four deaths, all in the nonoperative group and three weighing less than 1,000 g. None of the deaths were directly attributable to the perforations. In retrospect, each child presented with one or more early clues to the diagnosis of pharyngoesophageal perforation, which included a history of difficult tracheal or nasogastric intubation, blood in the nasogastric tube, length and course of nasogastric tube inserted, and subtle chest x-ray changes. In these cases, nonoperative treatment is usually successful.

Diagnosis, Differential↗
PubMedDate not supplied

Prognostic markers in localized prostate cancer: from microscopes to molecules.

Management of patients diagnosed with localized prostate cancer is complicated by the diverse natural history of the disease and variable response to treatment. Prognostic criteria currently in use cannot fully predict tumor behavior and thus limit the ability to recommend treatment regimens with the assurance that they are the best course of action for each individual patient. The search for better prognostic markers is now focussed on the molecular mechanisms which underlay tumor behavior, such as altered cell cycle progression, apoptosis, neuroendocrine differentiation, and angiogenesis. As the number of potential molecular markers increases, it is becoming evident that no single marker will provide the prognostic information necessary to make a significant improvement in patient care. In addition, it seems likely that traditional methods of assessing the prognostic value of this multitude of new markers will prove inadequate. In this review, we briefly examine the current state of prognostication in localized prostate cancer and some of the promising new molecular markers. Next, we examine how new technologies may allow the multiplex analysis of vast numbers of markers and how computational methods such as artificial neural networks will provide meaningful interpretation of the data. In the near future, such an integrated approach may provide a comprehensive prognostic tool for localized prostate cancer.

Antigens, Surface↗
PubMedDate not supplied

Lack of influence of c-Ha-ras expression on the drug sensitivity of human bladder cancer histocultured in three-dimensions.

The mechanism of drug resistance in human cancers is complex. In addition to overexpression of a series of multiple-drug-resistance genes, there has been the suggestion that the Ha-ras gene may participate in conferring resistance. In this study, a series of three human-bladder carcinoma cell lines were studied, one parental type, one transfected by wild-type Ha-ras and another transfected by mutant Ha-ras. The ras gene was overexpressed in the latter two cell lines which also were more invasive than the parental when injected as individual cells in the nude-mouse bladder. The results described here have indicated that the ras-gene expression level or mutational status did not affect drug resistance when the tumor lines were histocultured as three-dimensional tissue on collagen-sponge-gels. The drug-response spectrum of the histocultured lines qualitatively reflected a clinical experience although all lines were relatively drug resistant, possibly reflecting their three-dimensional configuration in culture.

Animals↗