Metformin reverses fatty liver disease in obese, leptin-deficient mice.

There is no known treatment for fatty liver, a ubiquitous cause of chronic liver disease. However, because it is associated with hyperinsulinemia and insulin-resistance, insulin-sensitizing agents might be beneficial. To evaluate this possibility, insulin-resistant ob/ob mice with fatty livers were treated with metformin, an agent that improves hepatic insulin-resistance. Metformin improved fatty liver disease, reversing hepatomegaly, steatosis and aminotransferase abnormalities. The therapeutic mechanism likely involves inhibited hepatic expression of tumor necrosis factor (TNF) alpha and TNF-inducible factors that promote hepatic lipid accumulation and ATP depletion. These findings suggest a mechanism of action for metformin and identify novel therapeutic targets in insulin-resistant states.

Reduced food intake and body weight in mice treated with fatty acid synthase inhibitors.

With the escalation of obesity-related disease, there is great interest in defining the mechanisms that control appetite and body weight. We have identified a link between anabolic energy metabolism and appetite control. Both systemic and intracerebroventricular treatment of mice with fatty acid synthase (FAS) inhibitors (cerulenin and a synthetic compound C75) led to inhibition of feeding and dramatic weight loss. C75 inhibited expression of the prophagic signal neuropeptide Y in the hypothalamus and acted in a leptin-independent manner that appears to be mediated by malonyl-coenzyme A. Thus, FAS may represent an important link in feeding regulation and may be a potential therapeutic target.

AMP-activated protein kinase and human cancer: cancer metabolism revisited.

AMP-activated protein kinase (AMPK) and its upstream kinase, LKB1, act to both monitor and restore cellular energy in response to energy depletion. Studied extensively in liver and skeletal muscle, AMPK is phosphorylated and activated by LKB1 in response to increasing AMP/ATP ratios, which occur in a variety of settings including hypoxia, nutrient starvation and redox imbalance. Interest in the roles of both AMPK and LKB1 in cancer has grown substantially, following the identification of LKB1 as the tumor suppressor gene mutated in the Peutz-Jegher familial cancer syndrome. Patients with the Peutz-Jegher syndrome harbor a single inactive LKB1 gene, and acquisition of a second inactivating lesion (loss of heterozygosity) leads to the development of the cancer in a variety of organs. Thus, the loss of AMPK activation is hypothesized to promote the development of malignancy. Conversely, pharmacological AMPK activation has recently been shown to be cytotoxic to many established human cancer cell lines in vitro and in human cancer xenograft and mouse cancer allografts. Previously, changes in cell metabolism that accompanied the malignant phenotype have largely been considered a consequence of cellular transformation. Now, AMPK and energy metabolism are linked to the development and maintenance of the malignant phenotype. These findings have led to renewed interest in AMPK and cancer cell metabolism in general as potential targets for cancer therapy.

Structure of pp32, an acidic nuclear protein which inhibits oncogene-induced formation of transformed foci.

pp32 is a nuclear protein found highly expressed in normal tissues in those cells capable of self-renewal and in neoplastic cells. We report the cloning of cDNAs encoding human and murine pp32. The clones encode a 28.6-kDa protein; approximately two-thirds of the N-terminal predicts an amphipathic alpha helix containing two possible nuclear localization signals and a potential leucine zipper motif. The C-terminal third is exceptionally acidic, comprised of approximately 70% aspartic and glutamic acid residues; the predicted pI of human pp32 is 3.81. Human and murine pp32 cDNAs are 88% identical; the predicted proteins are 89% identical and 95% similar. Although the structure of pp32 is suggestive of a transcription factor, pp32 did not significantly modulate transcription of a reporter construct when fused to the Gal4 DNA-binding domain. In contrast, in cotransfection experiments, pp32 inhibited the ability of a broad assortment of oncogene pairs to transform rat embryo fibroblasts, including ras + myc, ras + jun, ras + E1a, ras + mutant p53, and E6 + E7. In related experiments, pp32 inhibited the ability of Rat 1a-myc cells to grow in soft agar, whereas it failed to affect ras-induced focus formation in NIH3T3 cells. These results suggest that pp32 may play a key role in self-renewing cell populations where it may act in the nucleus to limit their sensitivity to transformation.

Fatty acid synthase (FAS): a target for cytotoxic antimetabolites in HL60 promyelocytic leukemia cells.

Many human cancers express elevated levels of fatty acid synthase (FAS), with correspondingly increased fatty acid synthesis and abnormal fatty acid utilization. Recent studies have shown that the FAS inhibitor, cerulenin, is selectively cytotoxic to cell lines derived from human malignancies, suggesting that those carcinoma cells are dependent upon endogenous fatty acid synthesis for growth. These data further suggest that the fatty acid synthesis pathway is a potential target for chemotherapy development. The present studies demonstrate that cerulenin cytotoxicity is mediated by fatty acid pathway inhibition. Proliferating HL60 promyelocytic leukemia cells express high levels of FAS mRNA and protein and synthesize fatty acid predominantly for membrane phospholipid. Following exposure to 12-O-tetradecanoylphorbol-13-acetate, the FAS expression in HL60 cells is abolished, fatty acid synthesis diminishes, and the cells become insensitive to cerulenin while acquiring a differentiated, macrophage-like phenotype. HL60 cells adapted to growth in serum- and fatty acid-free medium show a dose-dependent sensitivity to cerulenin, which is reversed by palmitate, the major product of FAS, indicating that cerulenin cytotoxicity is mediated through fatty acid starvation. Cells grown in the presence of exogenous fatty acid partially downmodulate FAS expression and increase mean cell volume (phospholipid mass/cell) but retain their sensitivity to cerulenin, which is reversed by 3-fold excess oleate supplementation. These results demonstrate that malignant cells can retain dependence on endogenous fatty acid synthesis and sensitivity to FAS inhibitors in the presence of physiological fatty acid levels and thus support the notion that FAS inhibitors may be useful in treating cancer in vivo.

Inhibition of fatty acid synthesis induces programmed cell death in human breast cancer cells.

One of the key limiting factors in the treatment of advanced stage human epithelial malignancies is the lack of new, selective molecular targets for antineoplastic therapy. A substantial subset of human breast, ovarian, endometrial, colorectal, and prostatic cancers express elevated levels of fatty acid synthase, the major enzyme required for endogenous fatty acid biosynthesis, and carcinoma lines are growth inhibited by cerulenin, a noncompetitive inhibitor of fatty acid synthase. We have shown previously that the difference in fatty acid biosynthesis between cancer and normal cells is an exploitable target for metabolic inhibitors in the in vitro setting and in vivo in a human ovarian carcinoma xenograft in nude mice. Here, we report that cerulenin treatment of human breast cancer cells inhibits fatty acid synthesis within 6 h after exposure, that loss of clonogenic capacity occurs within the same interval, and that DNA fragmentation and morphological changes characteristic of apoptosis ensue.

Malonyl-coenzyme-A is a potential mediator of cytotoxicity induced by fatty-acid synthase inhibition in human breast cancer cells and xenografts.

A biologically aggressive subset of human breast cancers and other malignancies is characterized by elevated fatty-acid synthase (FAS) enzyme expression, elevated fatty acid (FA) synthesis, and selective sensitivity to pharmacological inhibition of FAS activity by cerulenin or the novel compound C75. In this study, inhibition of FA synthesis at the physiologically regulated step of carboxylation of acetyl-CoA to malonyl-CoA by 5-(tetradecyloxy)-2-furoic acid (TOFA) was not cytotoxic to breast cancer cells in clonogenic assays. FAS inhibitors induced a rapid increase in intracellular malonyl-CoA to several fold above control levels, whereas TOFA reduced intracellular malonyl-CoA by 60%. Simultaneous exposure of breast cancer cells to TOFA and an FAS inhibitor resulted in significantly reduced cytotoxicity and apoptosis. Subcutaneous xenografts of MCF7 breast cancer cells in nude mice treated with C75 showed FA synthesis inhibition, apoptosis, and inhibition of tumor growth to less than 1/8 of control volumes, without comparable toxicity in normal tissues. The data suggest that differences in intermediary metabolism render tumor cells susceptible to toxic fluxes in malonyl-CoA, both in vitro and in vivo.

Inhibition of fatty acid synthesis delays disease progression in a xenograft model of ovarian cancer.

One of the key limiting factors in the treatment of advanced stage human epithelial malignancies is the lack of selective molecular targets for antineoplastic therapy. A substantial subset of human ovarian, endometrial, breast, colorectal, and prostatic cancers exhibit increased endogenous fatty acid biosynthesis and overexpress certain enzymes in the pathway. Cell lines derived from these tumors use endogenously synthesized fatty acids for cellular functions, whereas normal cells and tissues appear to utilize dietary lipids preferentially. We have previously shown that the difference in fatty acid biosynthesis between cancer and normal cells is an exploitable target for metabolic inhibitors in vitro. Here, we report observations in vivo using the i.p. model of the multiply drug-resistant OVCAR-3 human ovarian carcinoma in nude mice which demonstrate that: (a) fatty acid synthase overexpression in OVCAR-3 is comparable to levels in primary human tumors assessed by immunohistochemistry; (b) fatty acid synthetic activity of OVCAR-3 is comparably elevated in vitro and in vivo and is 4 to >20-fold higher than normal murine tissues; (c) treatment with the specific fatty acid synthase inhibitor, cerulenin, markedly reduces tumor cell fatty acid biosynthesis in vivo; (d) fatty acid synthase inhibition produces regression of established ascites tumor; and (e) treatment with cerulenin causes reduction in ascites incidence, delay in onset of ascites, and significantly increased survival (P<0.04).

A new biomarker in monitoring breast cancer: CA 549.

Serum biomarkers are not very reliable in assessing outcome or predicting recurrence of breast cancer. Clinically, carcinoembryonic antigen (CEA) is widely used and is elevated in a majority of patients with metastatic breast cancer. However, it is falsely elevated in a wide range of nonmalignant conditions and correlates poorly with disease progression. We evaluated a newly described monoclonal antibody, CA 549, in an immunoradiometric assay which uses two monoclonal antibodies directed against tumor and milk fat globule membranes. CA 549 and CEA were studied in 682 patients, 331 of whom had breast diseases and 99 of whom were followed with multiple serum samples. Of 69 patients with benign breast diseases, 1.5% had elevated CA 549, 0% of 30 pregnant women had elevated CA 549, and 26% of patients with nonmalignant liver disease had CA 549 elevation. In metastatic cancer of prostate, ovary, endometrium, colon, and lung CA 549 was elevated in 12% to 50% of cases with levels less than 120 U/mL. In breast cancer, CA 549 was elevated in 11% of 88 patients who received adjuvant chemotherapy and had no evidence of metastasis; in 23% of 16 patients in complete remission after chemotherapy; in 63% of 52 patients in partial remission after therapy; and in 83% of 106 patients with progression of breast cancer compared with 63% with elevated CEA (P = .001). In diseases of the breast, CA 549 has a sensitivity In diseases of the breast, CA 549 has a sensitivity and specificity of 77% and 92% v 61% and 92% for CEA. Of 99 patients serially monitored with clinically documented breast cancer progression, regression, or stability of disease, CA 549 was statistically significantly superior to CEA in monitoring a greater than 25% change in those patients with metastatic progression (P = .03). CA 549 is a new serum marker that should be control tested in prospective clinical trials alone or in conjunction with other markers.

Increased fatty acid synthase is a therapeutic target in mesothelioma.

Many common human cancer tissues express high levels of fatty acid synthase (FAS), the primary enzyme for the synthesis of fatty acids, and the differential expression of FAS between normal and neoplastic tissues has led to the consideration of FAS as a target for anticancer therapy. To investigate the potential of targeting FAS for the treatment of pleural mesothelioma, we first determined whether FAS is overexpressed in human mesothelioma. By immunohistochemistry, we found 22 of 30 human mesothelioma tissue samples tested to express significantly increased levels of FAS compared with normal tissues, including mesothelium. To further explore FAS as a therapeutic target in mesothelioma, we established a nude mouse xenograft model for human mesothelioma using the H-Meso cell line. The i.p. xenografts of this cell line have high levels of FAS expression and fatty acid synthesis pathway activity and grow along mesothelial surfaces in a manner similar to the growth pattern of human mesothelioma. Growth of these tumor xenografts was essentially abolished in mice treated with weekly i.p. injections of C75, a synthetic, small molecule inhibitor of FAS, at levels that resulted in no significant systemic toxicity except for reversible weight loss. These results suggest that FAS may be an effective target for pharmacological therapy in a high proportion of human mesotheliomas.

Enzymes of the fatty acid synthesis pathway are highly expressed in in situ breast carcinoma.

Expression of high levels of fatty acid synthase (FAS), an important enzyme in fatty acid synthesis, has been identified in a wide variety of human carcinomas. In breast and prostate carcinoma, FAS expression appears to be associated with aggressive disease. Recent biochemical studies have demonstrated that FAS expression in cancer cells connotes activation of the entire fatty acid synthesis pathway leading to the production of palmitic acid. Here, we explore the immunohistochemical expression of FAS and human acetyl-CoA carboxylase (HACC), the rate-limiting enzyme in fatty acid synthesis, in breast cancer progression from histologically normal breast through the development of in situ duct and lobular carcinoma to infiltrating carcinoma. Both FAS and the Mr 275,000 isoform of HACC are expressed in a small subset of cells in normal breast lobules and terminal ducts. Upon development of either in situ duct or lobular carcinoma, FAS and both isoforms of HACC are expressed at higher levels and in a majority of the cells. These findings suggest that expression of the enzymes of fatty acid synthesis are frequently altered early in the progression of human breast carcinoma.

pp32 overexpression induces nuclear pleomorphism in rat prostatic carcinoma cells.

Nuclear pleomorphism is an important diagnostic factor in tumour pathology. Traditionally, nuclear pleomorphism is evaluated qualitatively or semiquantitatively, often as a component of tumour grade; the molecular basis of nuclear pleomorphism, however, remains unclear. In this study, we investigated the quantitative effects on nuclear morphology of overexpressing pp32, a recently described nuclear phosphoprotein highly expressed in self-renewing and neoplastic cell populations. Assessment of Feulgen-stained transfected and control lines of AT3.1, a rat prostatic carcinoma cell line, using a computerized Cellular Image Analysis System (BD CAS-200) showed that stable overexpression of human pp32 in AT3.1 cells is accompanied by marked increases in the coefficient of variation of nuclear shape, nuclear size and chromatin textures but not in DNA content. In contrast, stable transfection with control vector, with ras, or with bcl-2 failed to affect nuclear morphology. Cell cycle analysis further showed that pp32-related increases in variation of nuclear structure manifested principally in G1. These studies suggest that pp32 plays a role either directly or indirectly in the control of nuclear shape of G1 cells.

Gonadal morphology in patients receiving chemotherapy for leukemia. Evidence for reproductive potential and against a testicular tumor sanctuary.

To evaluate the possible reproductive potential in patients who receive chemotherapy for leukemia, we reviewed the gonadal histologic findings at autopsy in 183 treated leukemic patients and in 183 age- and sex-matched control subjects. The 103 male leukemic patients had significantly reduced spermatogenic activity and tubular fertility index and increased interstitial fibrosis as compared with control subjects (p less than 0.001). The 80 females had marked reduction of secondary follicles (p less than 0.001). These lesions showed no predilection for grouping by sexual maturity or by leukemia diagnosis. There was no correlation with the type of chemotherapy or time since last dose of any antileukemic agent. Despite these extensive pathologic changes, there was histologic evidence of residual reproductive potential--a tubular fertility index greater than zero in 65 percent of males and intact primary follicles in 81 percent of premenopausal females. Testicular leukemia was present in 25 percent of males; all of the patients with testicular leukemia had additional foci of leukemia in other organs. The study shows histologic evidence of possible reproductive potential in treated leukemic patients of both sexes and does not support the concept of the testis as a tumor sanctuary in leukemia.

Polypoid squamous carcinoma of the esophagus. A case report with immunostaining for keratin.

Polypoid carcinoma of the esophagus is a rare variant of squamous carcinoma, which occurs typically in elderly patients who present with symptoms of dysphagia. This tumor has been given a variety of names, including spindle cell carcinoma, carcinosarcoma, and pseudosarcoma. These designations reflect the controversy surrounding the nature of the spindle cell component of this lesion. We have studied a case of polypoid carcinoma of the esophagus with immunoperoxidase staining for keratin which has been shown to be specific for epithelial cells. Positive staining for keratin was demonstrated in both the carcinomatous and spindle cell "sarcomatous" appearing components of the tumor, supporting the contention that this tumor is of entirely epithelial origin.

Fatty acid synthase (FAS) expression in human breast cancer cell culture supernatants and in breast cancer patients.

Fatty acid synthase (FAS) is selectively expressed in certain human cancers, including carcinoma of the breast, prostate, colon, ovary, and endometrium, compared to normal human tissues and therefore is a putative tumor marker. In this study, we found FAS concentrations were elevated in cell culture supernatants during cell growth in two human breast cancer cell lines but not other cancer cell lines. A quantitative enzyme-linked immunosorbent assay and Western blot analysis were employed in this study. In addition, serum FAS levels were significantly higher in breast cancer patients with different clinical stages (Stage II: 0.59+/-0.09 units/l, Stage III: 0.79+/-0.13 units/l, and Stage IV: 1.39+/-0.35 units/l) compared with healthy subjects (0.27+/-0.02 units/l, P<0.05). Taken together, our data suggest that FAS expression may be a useful tumor marker for breast cancer and play a role in assessing cancer virulence.

Immunoperoxidase stains of ganglion cells and abnormal mucosal nerve proliferations in Hirschsprung's disease.

Hirschsprung's disease is congenital aganglionosis of the distal colon. The affected bowel shows an abnormal proliferation of mucosal nerve fibers by acetylcholinesterase stains. We retrospectively reviewed biopsy specimens from patients with suspected and proven Hirschsprung's disease, performed immunoperoxidase stains for S-100 protein and neuron-specific enolase (NSE), and compared these results to routine histologic findings and acetylcholinesterase stains. Ganglion cells were demonstrated by immunoperoxidase in 63 of 69 specimens containing ganglion cells and in 1 specimen interpreted as aganglionic by hematoxylin-eosin staining. Increased numbers of nerve fibers in the muscularis mucosae and deep lamina propria by S-100 staining were detected in 8 of 8 specimens diagnostic for Hirschsprung's disease by hematoxylin-eosin and acetylcholinesterase stains and in 1 specimen diagnostic for colonic neuronal dysplasia (a disorder related to Hirschsprung's disease). Whereas 45 of 67 specimens from unaffected bowel showed a normal number and distribution of nerve fibers by S-100 staining, in 22 the pattern resembled that of Hirschsprung's disease. Specimens from affected colon also showed hypertrophied submucosal nerve trunks by S-100 stain (average nerve trunk thickness, 29.8 micron in affected bowel, 16.1 micron in unaffected segments--p less than 0.03). We conclude that NSE and S-100 stains are of value in demonstrating ganglion cells in suspected cases of Hirschsprung's disease and colonic neuronal dysplasia. The acetylcholinesterase stain is preferred over S-100 stain for detecting mucosal nerve proliferations in affected bowel. Submucosal nerve trunk thickness, although significantly different in affected and unaffected colon, is not of diagnostic value because of the wide variation in the measurements in the two groups.

Prostate-specific acid phosphatase immunoreactivity in adenocarcinomas of the urinary bladder.

Fifteen urinary bladder adenocarcinomas and nine bladder tumors with mixed glandular and transitional features were studied with antisera to prostate-specific antigen (PSA) and prostate-specific acid phosphatase (PSAP). The study was repeated with antisera from different companies to assess the reproducibility of the results. Of the 11 adenocarcinomas in men, three were positive for PSAP. Of the five tumors with mixed glandular and transitional features in men, one showed PSAP immunoreactivity. In the female subjects, PSAP staining was seen in two of the four adenocarcinomas and two of the four mixed glandular and transitional cell carcinomas. None of the tumors seen in either the male or female groups was considered positive for PSA.

Thorotrast-associated hepatic leiomyosarcoma and cholangiocarcinoma in a single patient.

A 66-year-old man developed two distinct primary malignant hepatic neoplasms (leiomyosarcoma and cholangiocarcinoma) 50 years after Thorotrast administration. This is the first case report of Thorotrast-associated primary hepatic leiomyosarcoma. Ultrastructural and immunohistochemical studies are discussed.

Pregnancy-associated plasma protein A: a clinically significant predictor of early recurrence in stage II breast carcinoma.

The primary tumors and metastases from 30 patients with stage II breast carcinoma treated with low- or standard-dose combination chemotherapy (cyclophosphamide, methotrexate, 5-fluorouracil) were studied by the immunoperoxidase technique for pregnancy-associated plasma protein A (PAPP-A), pregnancy-specific beta-1-glycoprotein (SP-1), and placental protein five (PP-5). In addition to immunostaining, 25 traditional clinicopathologic features were assessed with respect to early (at less than two years) recurrence. Of the 11 patients with early recurrences, nine (82 per cent) were PAPP-A-positive, while 16 of the 19 patients without early recurrences (84 per cent) were PAPP-A-negative (P less than 0.0005). None of the other clinicopathologic features correlated with early recurrence. Immunostaining for PAPP-A is thus a clinically significant predictor of early recurrence in patients with stage II breast carcinoma.

Esthesioneuroblastoma. Intermediate filaments, neuroendocrine, and tissue-specific antigens.

Esthesioneuroblastoma (EN), a malignant neuroblastic tumor arising in the superior portion of the nasal cavity, shares histologic similarities with a number of primary malignant tumors that arise in this region, including rhabdomyosarcoma, lymphoepithelioma, and lymphoma. To establish an antigenic profile of EN as an aid in the differential diagnosis of these histologically similar nasal tumors, immunostaining was performed for the following intermediate filaments: keratin, neurofilament, glial fibrillary acidic protein, and desmin; neuron-specific enolase (NSE), S-100 protein, chromogranin, human common leukocyte antigen (HLE), epithelial membrane antigen (EMA), myoglobin, and carcinoembryonic antigen (CEA) on 21 primary nasal tumors: eight EN, five lymphoepitheliomas, two small cell carcinomas, three lymphomas, and three rhabdomyosarcomas. Keratin and CEA stained only the carcinomas (6/7+, 4/7+), respectively; desmin and myoglobin only rhabdomyosarcoma (3/3+, 1/3+); and HLE only lymphomas (3/3+). Chromogranin and neurofilament staining occurred exclusively in one case each of EN. S-100 and NSE commonly stained EN (5/8+, 6/8+), but carcinomas (1/7+, 2/7+) and rhabdomyosarcomas (1/3+, 3/3+) were also positive. Despite the apparent nonspecificity of NSE and S-100, an antigenic profile of positive NSE of S-100 staining with negative epithelial, muscle, and lymphoid antigens uniquely identified six of eight EN. Chromogranin and neurofilament positivity was further evidence for EN in two cases. This antigenic profile is a helpful adjunct in the diagnosis of EN and other primary malignant nasal tumors.