Lipid-associated sialoprotein in the cerebrospinal fluid: association with brain malignancies.

BACKGROUND: Changes in the glycosylation process by tumor cells result in larger amounts of sialoproteins on their surface compared with normal cells. Sialoproteins then are released into the surrounding environment primarily by shedding or cell lysis. In the current study, the authors attempted to evaluate whether lipid-associated sialoprotein (LSP) in the cerebrospinal fluid (CSF) can distinguish patients with primary and metastatic brain tumors from those without brain tumors as well as determine response to treatment. METHODS: CSF samples were obtained from a tissue bank. The concentration of LSP was determined after chloroform:methanol extraction followed by protein precipitation. One-way analysis of variance and Scheffe pairwise comparisons were used for statistical analysis. RESULTS: The CSF of neurologically normal controls, patients with a normal leukocyte count (< or = 5/microl), and patients with various neurologic disorders or systemic tumors without central nervous system (CNS) malignancies contained similar levels of LSP. The CSF from patients with a normal leukocyte count and newly diagnosed primary or metastatic brain tumors contained on average 3.7-fold higher levels of LSP compared with CSF from patients without CNS tumors (P = 0.0001). The CSF from patients with brain tumors with progressive disease not responding to treatment contained high levels of LSP comparable to the levels found in newly diagnosed patients. The CSF from treatment-responsive patients contained decreased levels of LSP similar to that found in control patients. CONCLUSIONS: The LSP in CSF may be a useful marker with which to determine the presence of intracranial malignancies and assess response to treatment.

A novel U2 and U11/U12 snRNP protein that associates with the pre-mRNA branch site.

Previous UV cross-linking studies demonstrated that, upon integration of the U2 snRNP into the spliceosome, a 14 kDa protein (p14) interacts directly with the branch adenosine, the nucleophile for the first transesterification step of splicing. We have identified the cDNA encoding this protein by microsequencing a 14 kDa protein isolated from U2-type spliceosomes. This protein contains an RNA recognition motif and is highly conserved across species. Antibodies raised against this cDNA-encoded protein precipitated the 14 kDa protein cross-linked to the branch adenosine, confirming the identity of the p14 cDNA. A combination of immunoblotting, protein microsequencing and immunoprecipitation revealed that p14 is a component of both 17S U2 and 18S U11/U12 snRNPs, suggesting that it contributes to the interaction of these snRNPs with the branch sites of U2- and U12-type pre-mRNAs, respectively. p14 was also shown to be a subunit of the heteromeric splicing factor SF3b and to interact directly with SF3b155. Immuno precipitations indicated that p14 is present in U12-type spliceosomes, consistent with the idea that branch point selection is similar in the major and minor spliceosomes.

Gangliosides as targets for immunotherapy for pancreatic adenocarcinoma.

BACKGROUND: Pancreatic adenocarcinoma cells express gangliosides and sialyl Lewis (sLe) antigens. It is not known whether these carbohydrate antigens can be targeted by immunotherapy. The authors measured the expression of GM(2) and sLe antigens on the surface of pancreatic carcinoma cells and the serum levels of total gangliosides, GM(2), and antiganglioside antibodies in patients with pancreatic carcinoma. METHODS: Cell surface GM(2) and sLe antigens were measured by cell suspension enzyme linked immunoadsorbent assay (ELISA) in four pancreatic carcinoma cell lines. Sera from 20 pancreatic carcinoma patients and 20 age- and gender-matched healthy volunteers were analyzed for antiganglioside and anti-sLe immunoglobulin (Ig) M titers by ELISA. Serum levels of total gangliosides and GM(2) also were measured. RESULTS: All cell lines expressed GM(2) and sLe antigens. When compared with age- and gender-matched volunteers, patients had significantly higher serum levels of total gangliosides (25.6 +/- 9.0 mg/dL vs. 15.6 +/- 2.7 mg/dL; P < 0.001), GM(2) (0.278 +/- 0.415 mg/dL vs. 0.013 +/- 0.018 mg/dL; P = 0.02), ELISA units of anti-GM(2) IgM antibody (368 +/- 95 vs. 155 +/- 25; P = 0.04) and anti-GD(1b) IgM antibody (351 +/- 91 vs. 138 +/- 26; P = 0.03), but not anti-sLe(x) IgM (1389 +/- 345 vs. 1081 +/- 224; P = 0.46) or anti-sLe(a) IgM antibody (1097 +/- 253 vs. 1200 +/- 315; P = 0.80). Patients with unresectable tumors had higher serum levels of total gangliosides compared with patients with resectable tumors, and a serum level > 25 mg/dL was found to correlate significantly with poor overall survival (P < 0.02). CONCLUSIONS: Increased serum levels of total gangliosides and GM(2) may reflect shedding or release of gangliosides from the surface of tumor cells. Production of IgM antibody against GM(2) and GD(1b) indicates that these gangliosides are immunogenic antigens that may be potential targets for effective active immunotherapy.

thy/liv-SCID-hu mice: a system for investigating the in vivo effects of multidrug therapy on plasma viremia and human immunodeficiency virus replication in lymphoid tissues.

Modified, human immunodeficiency virus (HIV)-inoculated thy/liv-SCID-hu mice were used to evaluate the in vivo efficacy of antiretroviral drugs. Ritonavir treatment alone initially suppressed plasma viremia, but the viremia recurred with the appearance of ritonavir-resistant HIV isolates. Multidrug therapy suppressed plasma HIV RNA to undetectable levels; however, plasma viremia returned after therapy was stopped, showing that the therapy did not completely suppress HIV infection in the thymic implant. When thy/liv-SCID-hu mice were treated with a combination of zidovudine, lamivudine, and ritonavir immediately after inoculation with HIV, cocultures of the thymic implants remained negative for HIV even 1 month after therapy was discontinued, suggesting that acute treatment can prevent the establishment of HIV infection. Thus, these modified thy/liv-SCID-hu mice should prove to be a useful system for evaluating the effectiveness of different antiretroviral therapies on acute and chronic HIV infection.

SCID-hu mice: a model for studying disseminated HIV infection.

Modifications that we introduced into the implantation of human fetal thymus and liver into SCID mice (thy/liv-SCID-hu mice) markedly increased the population of human T cells and monocytes present in the peripheral blood and peripheral lymphoid compartment of these mice. As a result, the modified thy/liv-SCID-hu mice developed disseminated HIV infection after intraimplant or i.p. inoculation. After chronic HIV infection of these mice, depletion of the peripheral human T cells was observed as reported in HIV-infected individuals. In addition, these mice also developed plasma viremia after infection with HIV. The peripheral blood mononuclear cells were responsive to in-vivo cytokine regulation as evidenced by induction of human IFN-gamma gene expression by human IL-12 and inhibition by human IL-10. Acute treatment with human IL-10 but not with human IL-12 inhibited the development of plasma viremia and HIV infection in thy/liv-SCID-hu mice inoculated with HIV-1(59), a clinical isolate. SCID mice transplanted with cultured human fetal bone marrow displayed significant engraftment of the mouse bone marrow with human precursor cells and population of the peripheral blood with human B cells and monocytes. The peripheral blood of these bone marrow-transplanted SCID mice also became populated with human T cells after they were implanted with human thymic tissue due to migration of human precursor cells from the mouse bone marrow to the implanted human thymus. Thus, these modified SCID-hu mice should prove to be a valuable in-vivo model for studying the immunopathogenesis of HIV infection and for examining the in-vivo efficacy of immunomodulatory, drug and gene therapy in modifying HIV infection.

Inhibition of acute in vivo human immunodeficiency virus infection by human interleukin 10 treatment of SCID mice implanted with human fetal thymus and liver.

To improve the usefulness of in vivo mode for the investigation of the pathophysiology of human immunodeficiency virus (HIV) infection, we modified the construction of SCID mice implanted with human fetal thymus and liver (thy/liv-SCID-hu mice) so that the peripheral blood of the mice contained significant numbers of human monocytes and T cells. After inoculation with HIV-1(59), a primary patient isolate capable of infecting monocytes and T cells, the modified thy/liv-SCID-hu mice developed disseminated HIV infection that was associated with plasma viremia. The development of plasma viremia and HIV infection in thy/liv-SCID-hu mice inoculated with HIV-1(59) was inhibited by acute treatment with human interleukin (IL) 10 but not with human IL-12. The human peripheral blood mononuclear cells in these modified thy/liv-SCID-hu mice were responsive to in vivo treatment with exogenous cytokines. Human interferon gamma expression in the circulating human peripheral blood mononuclear cells was induced by treatment with IL-12 and inhibited by treatment with IL-10. Thus, these modified thy/liv-SCID-hu mice should prove to be a valuable in vivo model for examining the role of immunomodulatory therapy in modifying HIV infection. Furthermore, our demonstration of the vivo inhibitory effect of IL-10 on acute HIV infection suggests that further studies may be warranted to evaluate whether there is a role for IL-10 therapy in preventing HIV infection in individuals soon after exposure to HIV such as for children born to HIV-infected mothers.

The role of lipid-associated sialic acid (LSA) and prostate specific antigen (PSA) in the follow-up of prostatic cancer.

According to the most recent US cancer statistics, prostatic cancer almost equals lung cancer as the most frequent cause of death from cancer in men. The search for diagnostic methods as well as control examinations have therefore gained great importance. The present study reveals that--in addition to rectal touch, sonography and biopsy of the prostate--the determination of both PSA as organ-specific marker and lipid-associated sialic acid (LSA) as a general tumor marker, is well suited for follow-up and monitoring treatment. With regard to the follow-up, the combined determination of PSA and LSA in serum of patients with prostatic cancer achieves a higher sensitivity as compared to PSA alone (increase of 30-40%). LSA is a good indicator for the presence of metastases. Therefore, the determination of LSA should become an integral part of treatment monitoring and detection of metastatic disease in patients with prostatic cancer.

Plasma protein-bound sialic acid in patients with colorectal polyps of known histology.

Protein-bound sialic acid (PBSA) was measured in serial plasma specimens from 62 healthy subjects, 48 patients with colorectal polyps, and 30 patients with colorectal adenocarcinomas. The mean plasma PBSA concentration in healthy smokers was significantly greater than that in healthy nonsmokers and healthy ex-smokers (P less than 0.0001). Villoglandular polyps were associated with higher plasma PBSA values than were the most benign hyperplastic polyps (P less than 0.025). Patients with the most neoplastic villoglandular and villous polyps had significantly greater (P less than 0.010-0.050) plasma PBSA values than healthy subjects. Polypectomy decreased the mean PBSA value significantly to the mean value for healthy subjects only for patients with villoglandular (P less than 0.010) or villous (P less than 0.050) polyps. Colorectal cancer patients had mean plasma PBSA concentrations significantly greater than those for the healthy subjects (P much less than 0.001) and the polyp patients (P much less than 0.001). Surgery significantly reduced (P less than 0.025) the mean PBSA value for the cancer patients to the mean PBSA value observed for the healthy subjects.

Circulating tumor markers in the monitoring of gynecologic malignancies.

Plasma from 262 patients with gynecologic malignancies was assayed for levels of circulating tumor markers (CA 125, LSA [lipid associated sialic acid in plasma, LASA-P (Dianon Systems, Inc., Stratford, CT )], Ca 19-9, and carcinoembryonic antigen [CEA]) and correlated with the patients' clinical status. In the patients with ovarian cancer the sensitivities of LSA and CA 125 for patients with clinical evidence of disease were 71% and 76% respectively; the specificities for patients with no clinical evidence of disease were 90% and 86% respectively. Using both tumor markers, a sensitivity of 84% and specificity of 85% was obtained. Additionally, CA 125 was elevated in 59% of patients with clinically advanced or recurrent endometrial cancer, and LSA was elevated in 63% of patients with clinical evidence of cervical cancer. Neither CEA nor CA 19-9 levels correlated with clinical status in patients with ovarian or cervical cancer. The values of Ca 125 and LSA were examined in relation to the findings at second-look surgery in patients with ovarian cancer. Absence of elevated tumor markers does not obviate the need for second-look surgery; the false negative rate for CA 125 was 40% (6/15). However, the finding of two elevated plasma markers 1 month or more apart, in ovarian cancer patients who were clinically free of disease, was strongly suggestive of recurrent cancer; 13 of 14 such patients showed this association. This latter finding may help to identify a group of patients in whom early surgical intervention is indicated.

Prevention of leukemia and the increase of plasma levels of lipid-bound sialic acid by allogeneic bone marrow transplantation in mice.

AKR/J (hereafter called AK) mice treated by total-body irradiation plus syngeneic marrow transplantation developed a leukemia-lymphoma complex and concomitantly showed increased levels of lipid-bound sialic acid as was also seen in untreated AK mice between 6 weeks and 6 and 11.5 months of age. C57BL/6J (hereafter called B6) mice did not show a leukemia-lymphoma complex and did not develop elevated levels of lipid-bound sialic acid with aging. B6----AK chimeras, prepared with B6 bone marrow deprived of Thy-1,2-positive cells prior to allogeneic transplantation and kept in laminar flow isolation, did not develop graft-versus-host reactions, lived long lives (observations carried up to 13 months), failed to develop leukemia-lymphoma, and had persistently low levels of lipid-bound sialic acid. These findings indicate that introduction of resistance by marrow transplantation can inhibit development of retrovirus-induced cancer and also prevents an increase in levels of a putative cancer indicator.

Lipid-associated sialic acid test for the detection of human cancer.

A rapid method for the measurement of serum and/or plasma, lipid-associated sialic acid levels has been developed. This test has been applied to 850 human sera of which 670 came from patients with nine categories of malignant disease, 80 from persons with benign disorders, and 100 from normal individuals. Lipid-associated sialic acid concentrations were found to be significantly increased (p less than 0.001) in all groups of cancer patients as compared to both those with benign diseases and normal controls. Test sensitivity in the detection of cancer ranged from 77 to 97%. Specificity was, respectively, 81 and 93% for the benign and normal groups. In small samples of patients, no association between test values and tumor burden was found. This test compares favorably with the most widely used tumor marker test, that for carcinoembryonic antigen.

Serum lipid-bound sialic acid as a marker in breast cancer.

The reliability of lipid-bound sialic acid (LSA) as a marker in breast cancer was evaluated in 78 normal subjects, 106 patients with benign breast disease, 64 patients with primary operable breast cancer, and 61 patients with recurrent metastatic breast cancer. LSA levels were determined before and after mastectomy and during chemotherapy in selected patients to determine the value of LSA in monitoring therapy and predicting response. LSA levels greater than 20 mg/dl were not seen in normal subjects but were present in patients with benign breast disease (13%), primary breast cancer (47%) and recurrent metastatic breast cancer (62%). LSA levels decreased after initiation of chemotherapy and remained low in patients clinically disease-free. Recurrences were associated with elevated LSA in patients failing chemotherapy or endocrine ablative surgery. LSA measurements appeared to be of limited value in the detection of breast cancer but serial measurements may be useful in assessing disease progression and identifying patients resistant to therapy.

Plasma lipid bound sialic acid in patients with prostate and bladder cancer.

Plasma lipid bound sialic acid (LSA) was measured in patients with prostate and bladder cancer to determine the usefulness of this biochemical marker in teh staging of malignant disease and in monitoring the efficacy of therapy. Patients with advanced stages of prostate cancer with bone metastases exhibited LSA levels significantly higher than normal subjects. Patients with bladder cancer showed elevations in LSA both in early noninvasive and in advanced stages of the disease. In both types of cancer, patients treated successfully and clinically free of disease did not have elevated LSA levels, whereas patients failing to respond to treatment had persistently high values.

Improved method to determine lipid bound sialic acid in plasma or serum.

An improved method for the determination of lipid bound sialic acid in plasma or serum is presented. Our earlier procedure has been shortened and simplified to utilize 44.7 lambda samples and it yields within experimental error the same values as the earlier method.