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F M Torti

Publications and source records attributed to F M Torti.

At least 55 records · Page 3Linked to original sources
PubMed1991

Iron-independent induction of ferritin H chain by tumor necrosis factor.

Iron increases the synthesis of the iron-storage protein, ferritin, largely by promoting translation of preexisting mRNAs for both the H and L ferritin isoforms (H, heavy, heart, acidic; L, light, liver, basic). We have recently cloned and sequenced a full-length cDNA to murine ferritin H and identified ferritin H as a gene induced by tumor necrosis factor alpha (TNF-alpha, cachectin). Using primary human myoblasts, we have now examined the relationship between TNF-alpha and iron in regulating ferritin. Four lines of evidence suggest that TNF-alpha regulates ferritin independently of iron. First, evaluation of mRNA showed that TNF-alpha increased ferritin H chain specifically, provoking no change in steady-state levels of ferritin L mRNA; iron, in contrast, increased the mRNA of both isoforms. Second, the increase in ferritin H protein synthesis observed during TNF-alpha treatment was dependent on an increase in ferritin H mRNA: actinomycin D blocked the TNF-alpha-induced changes in ferritin H but did not inhibit the translational induction of ferritin seen with iron treatment. Third, equal ferritin mRNA induction was observed in iron-loaded cells and in cells depleted of iron by a permeant chelator, 2,2'-dipyridyl. Fourth, ferritin H induction by TNF-alpha and iron was additive over the entire range of iron concentrations, even at TNF-alpha doses known to maximally stimulate ferritin H mRNA levels. Nonetheless, the role of iron in translational regulation of ferritin was retained in TNF-alpha-treated cells; effective biosynthesis of TNF-alpha-induced, H-subunit-predominant ferritin protein required iron and could be enhanced by treatment of the cells with additional iron or blocked by 2,2'-dipyridyl. Finally, we observed that the TNF-alpha-mediated increase in ferritin synthesis peaked at 8 hr and was followed by a decrease in both H and L isoferritin synthesis; the addition of iron, however, reversed the late-occurring depression in ferritin synthesis. This suggests that TNF-alpha-induced synthesis of H-rich ferritin may reduce the regulatory pool of intracellular iron, secondarily inhibiting iron-mediated translation of ferritin mRNA. We conclude that TNF-alpha acts independently of iron in its induction of ferritin H mRNA but requires the presence of iron for this effect to be fully expressed at the protein level.

2,2'-Dipyridyl↗
PubMed1991

Adjuvant intravesicular pharmacotherapy for superficial bladder cancer.

In 1990, bladder cancer, excluding carcinoma in situ, was estimated to contribute 49,000 cases of cancer. In men 75 years old or older, it became the fifth leading cause of cancer deaths. Of patients with bladder cancer, 75%-80% initially present with superficial bladder tumors. Treatment of these tumors has three objectives: 1) to eradicate existing disease, 2) to provide prophylaxis against tumor recurrence, and 3) to avoid deep invasion into the muscle layers of the bladder. Transurethral resection is the primary treatment to eradicate superficial bladder tumors, but 40%-80% of these tumors recur. Because of these high recurrence rates, adjuvant intravesicular pharmacotherapy with cytotoxic and immunomodulatory drugs has gained widespread use. The past two decades of clinical investigations in superficial bladder cancer have provided valuable information on the biology and treatment of the disease. Multivariate analyses have indicated that tumor grade and stage are the most important prognostic variables commonly available to the clinician to identify the patient at greatest risk of developing muscle-invasive or metastatic bladder cancer. These studies have also identified groups at low risk for tumor recurrence and invasive bladder cancer. Randomized trials have shown that recurrence rates are decreased by adjuvant intravesicular pharmacotherapy with a number of drugs: bacillus Calmette-Guérin vaccine (BCG), doxorubicin, ethoglucid (Epodyl), mitomycin-C, teniposide, and thiotepa. However, few studies indicate that adjuvant intravesicular pharmacotherapy can prevent progression to invasive bladder cancer in the high-risk patient with superficial bladder cancer. Additional clinical trials are needed to determine whether such therapy can prevent invasive and metastatic bladder cancer and improve disease-free survival in this group. In addition, the identification of tests (e.g., monoclonal antibody tests, chromosomal analyses, and tumor marker assays) that can help to identify high-risk patients is needed to better develop therapeutic strategies for superficial bladder cancer.

Antineoplastic Agents↗
PubMed1991

Tumor necrosis factor-alpha and interleukin 1-alpha regulate transferrin receptor in human diploid fibroblasts. Relationship to the induction of ferritin heavy chain.

We have studied transferrin receptor expression in MRC5 human fibroblasts in response to tumor necrosis factor-alpha (TNF, cachectin) or interleukin 1-alpha (IL-1). Treatment of exponentially growing MRC5 cells with these cytokines led to a 3-4-fold increase in transferrin receptor mRNA and a coordinate increase in transferrin receptor protein by 24 h. Under these conditions, stimulation of [3H]thymidine incorporation was minimal, suggesting that the induction of transferrin receptor by TNF and IL-1 is mediated by a growth-independent regulatory mechanism. A study of the time course of this response showed that cytokine-mediated increases in transferrin receptor mRNA and protein proceeded after a lag of 12-24 h. A simultaneous analysis of the effects of TNF and IL-1 on ferritin in MRC5 cells was also performed. Ferritin L mRNA levels were unchanged. However, induction of ferritin H mRNA was seen within 4 h, preceding the induction of the transferrin receptor. The synthesis of ferritin H (but not ferritin L) protein peaked at 8 h after TNF or IL-1 treatment, followed by a rapid decrease in both ferritin H and L protein synthesis. As ferritin H synthesis declined, levels of transferrin receptor protein increased, reaching a maximum by 24 h. These results suggest that the cytokine-dependent induction of ferritin H and subsequent increase in the transferrin receptor are related and possibly interdependent events. This study demonstrates that the complex role of TNF and IL-1 in iron homeostasis includes modulation of the transferrin receptor.

Cell Division↗
PubMed1991

Evaluation of mRNA levels by the polymerase chain reaction in small cardiac tissue samples.

Doxurubicin is an effective and widely used chemotherapeutic agent. However, use of this drug is often limited by its cardiotoxic side effects. We have observed that an early event accompanying doxorubicin cardiomyopathy is a selective decrease in levels of muscle gene transcripts in cardiac tissue (Ito et al., Proc. Natl. Acad. Sci. USA 87: 4275-4279). Since this decrease precedes ultrastructural evidence of cardiac damage, measurements of muscle transcripts might assist in the clinical evaluation of doxorubicin cardiotoxicity. We have therefore assessed the utility of the polymerase chain reaction in the measurement of mRNA in control and doxorubicin-treated animals. These measurements were performed on small tissue samples that simulate endomyocardial biopsies. We measured cardiac alpha-actin transcripts as a fraction of ferritin heavy chain transcripts using the method described by Chelly et al. (Nature 333: 858-860, 1988). 0.5 micrograms of total RNA, an amount equivalent to that obtainable from a typical endomyocardial biopsy, was efficiently co-amplified with cardiac alpha-actin and ferritin heavy chain specific primers. The cardiac alpha-actin/ferritin heavy chain ratio calculated from the PCR results correlated well (R = 0.981) with results obtained using Northern blot analysis of 10 micrograms RNA. The correlation was maintained over a wide range of cardiac alpha-actin transcript abundance. These results show that mRNA from cardiac tissue can be estimated by the polymerase chain reaction, even from a small, endomyocardial biopsy-sized sample.

Actins↗
PubMed1991

Stage T1 bladder cancer: grade is the primary determinant for risk of muscle invasion.

Tumor characteristics believed to predict for deep muscle invasion after transurethral resection of superficial bladder cancer alone were analyzed in 51 patients with stage T1 (stage A) transitional cell carcinoma of the bladder. All patients were treated at Stanford University Medical Center and none had intravesical chemotherapy at any time during the median followup of 78 months. No patient had carcinoma in situ. A total of 14 patients (27%) had deep muscle invasion. None of the patients with grade 1, 5 (22%) with grade 2 and 9 (50%) with grade 3 to 4 tumors had deep muscle invasion. Comparison of the risk of muscle invasion using pathological tumor grade at diagnosis, highest grade at any cystoscopic biopsy before the diagnosis of muscle invasion or highest grade at cystoscopic biopsy immediately antecedent to the cystoscopy at which muscle invasion was diagnosed all showed similar probability of muscle invasion. Mean interval to development of muscle invasion was 6 and 12 months in the grades 2 and 3 to 4 groups, respectively. At 36 months the cumulative probability of invasion-free survival was 62% for grade 2, compared to 50% for grades 3 to 4 cancer patients (p less than 0.005, Gehan). Univariate regression analysis demonstrated grade to be the only significant factor in predicting for invasive disease (p = 0.005), with tumors in the bladder neck to be of borderline significance (p = 0.159). On multivariate logistic regression analysis, grade remained the single tumor variable predicting for invasive bladder cancer (p = 0.004). These data suggest that of routinely available data at diagnosis and during subsequent followup cystoscopic examinations, tumor grade is the most important biological predictor of progression to muscle invasive cancer.

Aged↗
PubMed1991

Serum markers in germ cell neoplasms.

Innovations in the treatment of testicular cancer, including surveillance of clinical stage I patients and curative chemotherapy for disseminated disease, have increased the need for sensitive ways to stage and monitor patients, both during and after therapy. Serum tumor markers, in combination with radiographic studies, have significantly improved our ability to evaluate and treat patients with seminomas and NSGCT. Elevated AFP and BHCG levels provide prognostic information at diagnosis, indicate persistent disease following orchiectomy or RPLND, and signal a recurrence after chemotherapy. Significantly delayed clearance of markers during chemotherapy often indicates persistent disease. Serum markers help define the duration of therapy, thus minimizing the substantial toxicities often associated with curative chemotherapy. Despite these advances, areas of concern remain. A small percentage of patients with NSGCT and the majority of patients with seminoma have undetectable levels of AFP and BHCG. The search for additional sensitive and specific serum markers in these cases has not been wholly successful. LDH, PLAP, and BFP occasionally serve as useful markers in seminoma but suffer lack of specificity. In addition, normal postoperative or postchemotherapy serum marker levels do not always ensure complete remission. This is difficult clinically when residual masses persist following therapy. Resection is always required to rule out persistent disease. The next decade may reveal additional useful serum tumor markers and potentially new imaging techniques incorporating antimarker antibodies to differentiate necrotic tissue from active disease.

Biomarkers, Tumor↗
PubMed1990

Murine ferritin heavy chain: isolation and characterization of a functional gene.

A mouse liver genomic library screened with a full-length cDNA encoding murine ferritin heavy chain (mFHC) [Torti et al., J. Biol. Chem. 263 (1988) 12638-12644] yielded a functional genomic clone mFHC. The genomic clone isolated included a region of approximately 3 kb containing four exons and three introns. Sequence comparisons of the mouse genomic clone with other genomic clones from rat, human and chicken showed a high degree of similarity among species in the coding regions. Introns and flanking sequences were less conserved. However, comparison of mFHC promoter elements with FHC genes from other species revealed common elements. Analysis of the genomic structure of FHC suggested the presence of pseudogenes. S1 nuclease analysis, however, confirmed that this mouse clone, when transfected into human MRC-5 fibroblasts, was transcribed, indicating that this clone contains an FHC functional gene.

Animals↗
PubMed1990

Interleukin 1 induces ferritin heavy chain in human muscle cells.

Interleukin 1 alpha (IL-1) and tumor necrosis factor alpha (TNF) are two monokines which play a prominent role in the response to inflammation and injury. We recently observed that TNF leads to an increase in the synthesis of the heavy chain of ferritin, suggesting that TNF may be involved in iron homeostasis (Torti et al. (1988) J. Biol. Chem. 263, 12638-12644). The experiments reported here demonstrate that in cultured human muscle cells, IL-1 induces ferritin H mRNA and protein as effectively as TNF. TNF and IL-1 were additive in their effects on ferritin H expression, and IL-1 induction of ferritin H was not blocked by anti-TNF antibodies. Ferritin H induction was a specific response not observed with beta or gamma interferon, nor with transforming growth factor beta. Both differentiated myotubes as well as myoblasts responded to IL-1 with the induction of ferritin H. These results suggest that monokine-mediated alterations in the subunit composition of the ferritin molecule may be of biological relevance in the response to inflammation and injury.

Cells, Cultured↗
PubMed1990

Doxorubicin selectively inhibits muscle gene expression in cardiac muscle cells in vivo and in vitro.

The anthracycline antibiotic doxorubicin produces a characteristic myopathy in cardiac muscle that limits its use in cancer therapy. We have shown in cultured neonatal rat cardiac muscle cells that doxorubicin treatment resulted in a rapid, selective decrease in the expression of muscle-specific genes, which preceded other changes characteristic of doxorubicin cardiomyopathy. Doxorubicin selectively and dramatically decreased the levels of mRNA for the sarcomeric genes, alpha-actin, troponin I, and myosin light chain 2, as well as the muscle-specific, but nonsarcomeric M isoform of creatine kinase. However, doxorubicin did not affect nonmuscle gene transcripts (pyruvate kinase, ferritin heavy chain, and beta-actin). Actinomycin D, an inhibitor of DNA-dependent RNA polymerase, did not show a similar selective decrease of muscle-specific mRNAs but, rather, produced a nonspecific, dose-dependent decrease of muscle and nonmuscle transcripts. The doxorubicin effect on muscle gene expression was limited to cardiac muscle; cultured skeletal myocytes were resistant to the effects of doxorubicin at 100-fold greater doses than those causing changes in mRNA levels in cardiac muscle cells. These effects of doxorubicin were reproduced in vivo; rats injected with doxorubicin showed a dose-dependent decrease in the levels of mRNAs for alpha-actin, troponin I, myosin light chain 2, and M isoform of creatine kinase in cardiac but not skeletal muscle. These selective changes in gene expression in cardiocyte cultures and cardiac muscle precede classical ultrastructural changes and may explain the myofibrillar loss that characterizes doxorubicin cardiac injury.

Actins↗
PubMed1989

Evidence for two mechanisms by which tumor necrosis factor kills cells.

Tumor necrosis factor (TNF) can inhibit the differentiation of preadipocytes to adipocytes and will revert differentiated adipocytes to the preadipocyte state. TNF is not toxic to either adipocytes or preadipocytes when used alone but is highly toxic to these cells when used in conjunction with cycloheximide, yielding virtually 100% killing within 4-6 h of treatment. A cell line (TA1 R-6) was isolated which is resistant to the combined toxic effects of TNF and cycloheximide. This cell line is stable and, unlike the parental cell line, does not morphologically differentiate to adipocytes or express adipocyte-specific mRNAs. It has a more transformed appearance and growth pattern and, while resistant to the toxic effects of TNF and cycloheximide in a 6-h assay, has become sensitive to cytotoxicity induced by TNF used alone in a 3-day assay. The adipocyte differentiation-inducing agents, dexamethasone and indomethacin, block the cytotoxicity induced by TNF alone in the TA1 R-6 line but do not block the rapid cytotoxicity of TNF and cycloheximide in the parental line. These results provide both genetic and pharmacologic evidence that there are at least two distinct or overlapping pathways by which TNF mediates its effects.

Adipose Tissue↗
PubMed1989

Modulation of adipocyte differentiation by tumor necrosis factor and transforming growth factor beta.

Cultured TA1 adipocytes treated with tumor necrosis factor alpha (TNF) lose intracytoplasmic lipid and, over a period of days, come to resemble their predifferentiated progenitors (preadipocytes). To examine the extent to which this phenotypic reversion represents a return to a less differentiated cell, we examined three major characteristics that distinguish preadipocytes from adipocytes: (a) pattern of gene expression; (b) hormonal requirement for accelerated adipogenesis; and (c) pattern of protein synthesis. We found that within hours of TNF addition to adipocytes, mRNAs for genes whose expression is augmented during adipogenesis decreased to predifferentiated levels; in addition, like preadipocytes, TNF-treated adipocytes required exposure to hormones to accelerate adipogenesis. Further, the pattern of protein synthesis seen on polyacrylamide gels reverted to that seen before differentiation. Transforming growth factor-beta (TGF-beta) also caused a rapid decrease in expression of adipose genes when added to fully differentiated cells, an effect that was achieved by treatment with either TGF-beta 1 or TGF-beta 2. These effects were seen in the absence of a demonstrable proliferative response to either TNF or TGF-beta. Thus characteristics that define the "terminally" differentiated state in adipocytes are subject to modulation by environmental influences.

Adipose Tissue↗
PubMed1988

The molecular cloning and characterization of murine ferritin heavy chain, a tumor necrosis factor-inducible gene.

Ferritin is a ubiquitous and highly conserved protein which plays a major role in iron homeostasis. We have identified and sequenced a full-length cDNA for murine ferritin heavy chain. The isolated cDNA is 819 nucleotides in length. It includes 546 nucleotides which encode a protein of 182 amino acids, a 5' noncoding sequence of 120 nucleotides, and a 3'-noncoding region of 153 nucleotides. The sequence displays a high degree of homology to human ferritin H, and includes a portion of the iron-responsive element conserved in chick, frog, and human ferritin. Tumor necrosis factor (TNF), a cytokine which mediates elements of the stress response, induces expression of ferritin H mRNA. Both mouse TA1 adipocytes and human muscle cells increase expression of ferritin H mRNA 4-6-fold after 48 h exposure to TNF. This increase occurs both prior and subsequent to differentiation of adipocytes and muscle cells, and is accompanied by an increase in the synthesis of the ferritin H subunit. These findings suggest a novel role for TNF in iron metabolism.

Adipose Tissue↗
PubMed1988

Brain metastases from transitional cell carcinoma of the bladder.

We present our experience with 4 patients with transitional cell carcinoma of the bladder and brain metastases. In all 4 cases a solitary intracranial metastasis occurred. In 3 patients this represented the first site of recurrent disease following systemic chemotherapy. Aggressive therapy of the brain metastases was instituted in 3 patients, including external beam radiation and in 2 cases surgical resection. Although all patients died only 3 died as a result of metastatic transitional cell carcinoma, including 2 who died as a direct result of intracranial disease. A review of the literature suggests an increasing incidence of brain metastases from transitional cell carcinoma of the bladder with the advent of more aggressive therapy for bladder cancer, which includes radical surgery for high stage disease and combination chemotherapy. Aggressive intervention for solitary brain metastases from transitional cell carcinoma can relieve neurological dysfunction and may prolong survival.

Aged↗
PubMed1988

Tumor necrosis factor inhibits human myogenesis in vitro.

We examined the effects of human recombinant tumor necrosis factor-alpha (TNF) on human primary myoblasts. When added to proliferating myoblasts, TNF inhibited the expression of alpha-cardiac actin, a muscle-specific gene whose expression is observed at low levels in human myoblasts. TNF also inhibited muscle differentiation as measured by several parameters, including cell fusion and the expression of other muscle-specific genes, such as alpha-skeletal actin and myosin heavy chain. Muscle cells were sensitive to TNF in a narrow temporal window of differentiation. Northern (RNA) blot and immunofluorescence analyses revealed that human muscle gene expression became unresponsive to TNF coincident with myoblast differentiation. When TNF was added to differentiated myotubes, there was no effect on muscle gene expression. In contrast, TNF-inducible mRNAs such as interferon beta-2 still responded, suggesting that the signal mediated by TNF binding to its receptor had no effect on muscle-specific genes after differentiation.

Actins↗
PubMed1988

Alpha-interferon in superficial bladder cancer: a Northern California Oncology Group Study.

Thirty-five patients with superficial transitional carcinoma of the bladder were treated intravesically with escalating doses of recombinant alpha-2-interferon administered weekly for 8 weeks. Of the 19 patients with high-grade intraepithelial neoplasia (17 carcinoma in situ [CIS], two severe dysplasia, all cytology positive), six (32%) had complete resolution of all histologic and cytologic evidence of disease (complete response). An additional three patients (16%) had complete resolution of CIS, but the interval appearance of a low-grade transitional cell neoplasm. Five (26%) had a partial response (complete resolution of all evidence of CIS on multiple bladder biopsies but persistently positive cytologic preparations). Sixteen patients with recurrent papillary tumors and extensive prior therapy were also treated. Four (25%) had a complete response. Twenty-three of the 35 patients had prior intravesical therapy. Seven of the 23 (30%) patients with prior intravesical chemotherapy or immunotherapy had a complete or partial response to interferon, while eight of the 12 patients (67%) without prior intravesical treatment responded. These responses were achieved with minimal local and systemic toxicity. Of the ten complete responders, five remain in continuous unmaintained remission for 18+ to 37+ months. Intracavitary alpha-2-interferon is an effective new treatment for some patients with bladder cancer.

Adult↗