Treatment with bevacizumab (BEV) upregulates expression of the transcription factor Sp1 and its downstream target genes in human carcinoid cells: Molecular basis of the synergistic antiangiogenic activity of bevacizumab and mithramycin A (MIT)

15031

Background: Our previous studies show that human carcinoid cells overexpress pro-angiogenic factors, vascular endothelial growth factor A (VEGF), and transcription factor Sp1 plays a critical role in VEGF inducible and constitutive expression. However, the impact of antiangiogenic therapy on the Sp1/VEGF pathway remains unclear. Method: Groups of 10 athymic BALB/c nude mice were implanted with 1.5 million human H727 carcinoid cells. Treatment with VEGF neutralizing monoclonal antibody, BEV, MIT, or BEV + MIT was initiated once implanted tumor reached 4 mm in size. Result: Treatment with BEV, suppressed human carcinoid growth in nude mice (tumor size at week 5 1280 mm3 vs 480 mm3; p < 0.001). Gene expression analyses revealed that this treatment substantially upregulated the expression of Sp1 (7 folds) and its downstream target genes, including VEGF (5 folds) and epidermal growth factor receptor (4 folds), in tumor tissues, whereas it did not have this effect on carcinoid cells in culture. Treatment with mithramycin A, an Sp1 inhibitor, suppressed the expression of Sp1 and its downstream target genes in both cell culture and tumors growing in nude mice. Median survival of mice treated with PBS, BEV, MIT, and BEV + MIT groups were 88, 112, 121, and >160 days respectively (p < 0.001). Combined treatment with bevacizumab and mithramycin A produced synergistic tumor suppression, which was consistent with suppression of the expression of Sp1 and its downstream target genes. Conclusion: Treatment with bevacizumab may block VEGF function but activate the pathway of its expression via positive feedback. Given the fact that Sp1 is an important regulator of the expression of multiple angiogenic factors, bevacizumab-initiated upregulation of Sp1 and subsequent overexpression of its downstream target genes may affect the potential angiogenic phenotype and effectiveness of antiangiogenic strategies for human carcinoid.

No significant financial relationships to disclose.

Preferential inhibition of Sp1 expression in growing tumors by mithramycin-A (MIT) directly correlates with its potent antiangiogenic effects in human carcinoid xenograft model

15041

Background: MIT, also known as aureolic acid and plicamycin (Mithracin), is an aureolic acid-type polyketide produced by various soil bacteria of the genus Streptomyces. Previous studies have shown that MIT exhibits antitumor activity. In the present study, we examine the antiangiogenic effect of MIT and its underlying mechanisms. Methods: Cohorts of 10 athymic BALB/c nude mice were implanted with 1.5 million human H727 carcinoid cells. Mice were treated with subcutaneous or intraperitoneal 0.2 mg/kg of mithramycin twice weekly once implanted tumor reached 4 mm in size. Results: Both subcutaneous and intraperitoneal MIT significantly suppressed the growth of carcinoid cells in nude mouse models (median tumor weight in PBS, s.c., i.p. groups 790 mm3 vs 280 mm3, 480 mm3; P < 0.01). We also evaluated the Sp1 expression in growing tumors and various organs. We found that the liver expressed the highest level of Sp1 among normal organs (including liver, stomach, large intestine, and small intestine, spleen, kidney, brain and lymph node). However, Sp1 expression in the growing tumors was more than 10 times higher than that in a normal liver. Treatment with MIT reduced the Sp1 expression in the tumors, while no discernible effect on Sp1 expression in normal tissues was observed. This is the first demonstration that MIT selectively inhibited the Sp1 expression in the growing tumors. Consistent with the expression of Sp1, a substantial suppression of VEGF, PDGF, EGFR, and IGFR expression was evident. Finally, treatment with MIT reduced the microvessel formation in tumors by 80% (MVD count; P < 0.01). This antiangiogenic activity was confirmed by in vitro tubulogenesis assay and in vivo Matrigel plug assay. Conclusions: Collectively, our studies strongly indicate that MIT is a potent antiangiogenic agent and its mechanism of action involved suppression of Sp1 expression and its consequent downregulation of its downstream targets including VEGF, PDGF, EGFR, and IGFR that are key to tumor angiogenesis.

No significant financial relationships to disclose.

Association of VEGF expression with poor prognosis among patients with low-grade neuroendocrine carcinoma

4091

Background: Low-grade neuroendocrine carcinomas (LGNET) can arise from neuroendocrine cells throughout the body and have a wide range of aggressiveness. Reliable predictive and prognostic markers of outcome are lacking. Angiogenesis is critical for metastasis and tumor growth beyond a small tumor size and VEGF is a powerful mediator of tumor angiogenesis. Methods: LGNET tissue from 50 patients (24 with local-regional disease, 26 with metastasis) who underwent tumor resection at the University of Texas M.D. Anderson Cancer Center was evaluated for expression VEGF by immunohistochemistry. Chi-square and Fisher’s exact test were used to test the association between study parameters. Kaplan-Meier analysis was used to assess the affect of study parameters on progression free survival (PFS). Results: Strong, weak, and negative VEGF expression was observed in 32%, 54%, and 14% of cases respectively. Larger tumor size was observed among patients with strong VEGF expression. Mean tumor sizes in patients with strong, weak and negative VEGF were 4.8, 2.8, and 2.9 cm. Compared to the group with negative VEGF expression, VEGF (weak/strong) expression was associated with metastasis (14% v 58%; P = .045). The median PFS durations of patients with strong and weak VEGF expression were 29 months and 81 months respectively. With a median follow-up duration of 50 months, the median PFS duration for the group with negative VEGF expression has not been reached. Compared by log rank test VEGF expression was associated with poor PFS (P = .022). Conclusions: This study suggests that tissue VEGF expression is associated with aggressive tumor growth and metastasis among patients with LGNET. VEGF expression may serve as a useful prognostic marker following tumor resection.

No significant financial relationships to disclose.

Clinical study on effect of HBO plus electric stimulation on treatment for the vegetative state

We proposed neurological diagnostic criteria and new scoring system for the vegetative state (VS). According to these criteria and scoring system, we examined the effects of hyperbaric oxygen (HBO) treatment in 130 cases of VS. As compared with non-HBO treatment, HBO treated patients showed statistically significant recovery from VS.

A novel, clinically relevant animal model of metastatic pancreatic adenocarcinoma biology and therapy

In this study, we report a metastatic model of Panc02 murine pancreatic adenocarcinoma. Parental Panc02 cells were orthotopically implanted into the pancreas of syngeneic C57BL/6 mice. Tumor cells were isolated from liver micrometastases 90 d after tumor implantation and established as a culture (Panc02-H1). The Panc02-H1 cells were then implanted into the pancreas of mice. Liver metastases were then collected and established as Panc02-H2 cells. This process was repeated until the Panc02-H7 cell line was established. These cells were extremely aggressive after implantation as manifested by progressive growth in the pancreas, peritoneal dissemination, and distant metastasis to multiple organs, including the liver and lungs. Moreover, Panc02-H7 cells expressed the inducible nitric oxide synthase gene at a very low level in culture and produced highly vascularized tumors having a large number of infiltrating macrophages. Collectively, this model system should be a valuable tool for investigating the molecular mechanisms governing pancreatic cancer growth and metastasis and exploring potential treatment modalities for this disease.

Mouse models of metastatic pancreatic adenocarcinoma

Pancreatic adenocarcinoma is a deadly disease. Its etiology is unknown, and metastatic disease kills the majority of patients who have it. Effective prevention is clearly the ultimate goal for eradicating this disease provided that the effects of environmental and genetic elements on pancreatic cancer development are fully understood. Currently, it appears that the control of pancreatic cancer metastasis is of immediate urgency. Fulfillment of this difficult task relies on knowledge of the cellular and molecular biology of metastasis. The use of relevant animal models will help define each aspect of this complicated process.

Interleukin-8 and human cancer biology

The aggressive nature of metastatic human cancer has been shown to be related to numerous abnormalities in growth factors and their receptors. These perturbations confer a tremendous growth advantage to the malignant cells. Interleukin-8 (IL-8), originally discovered as a chemotactic factor for leukocytes, has recently been shown to contribute to human cancer progression through its potential functions as a mitogenic, angiogenic, and motogenic factor. While it is constitutively detected in human cancer tissues and established cell lines, IL-8 expression is regulated by various tumor microenvironment factors, such as hypoxia, acidosis, nitric oxide, and cell density. Understanding the mechanisms of both inducible and constitutive IL-8 expression will be helpful in designing potential therapeutic strategies of targeting IL-8 to control tumor growth and metastasis. In this review, the role and regulation of IL-8 expression in the growth and metastasis of human cancer with a focus on human pancreatic adenocarcinoma will be discussed.

Genetic disruption of host interferon-gamma drastically enhances the metastasis of pancreatic adenocarcinoma through impaired expression of inducible nitric oxide synthase

Synergistic induction of the inducible nitric oxide synthase (NOS II) gene requires a combination of interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS). In this study, we determined whether the induction of IFN-gamma was required for NOS II-mediated antitumor activity in vivo. Highly metastatic H7 murine pancreatic adenocarcinoma cells were implanted into the subcutis, footpad, and pancreas of syngeneic IFN-gamma(+/+) and IFN-gamma(-/-) mice. These cells grew and produced metastases and ascites in IFN-gamma(+/+) mice. In sharp contrast, the same tumor cells grew much more aggressively, metastasized more extensively, and produced a larger amount of malignant ascites in IFN-gamma(-/-) mice. Also, induction of IFN-gamma correlated with NOS II gene expression and NO production in IFN-gamma(+/+) injected with the tumor cells but not in IFN-gamma(-/-) mice or IFN-gamma(+/+) mice without tumor challenge. In vitro, only LPS plus IFN-gamma induced a high level of NO production and cytotoxicity against H7 cells. These data suggested that the tumor cells stimulated IFN-gamma secretion from host cells, which in turn stimulated NO production by host cells and suppressed tumor growth and metastasis.

p202, an interferon-inducible protein, mediates multiple antitumor activities in human pancreatic cancer xenograft models

p202, an IFN-inducible protein, interacts with certain transcriptional activators leading to transcriptional repression. p202 expression has been associated with inhibition of cancer cell growth in vitro and in vivo. To examine a potential p202-mediated antitumor activity in pancreatic cancer, we used both ectopic and orthotopic xenograft models and demonstrated that p202 expression is associated with multiple antitumor activities that include inhibition of tumor growth, reduced tumorigenicity, prolonged survival, and remarkably, suppression of metastasis and angiogenesis. In vitro invasion assay also showed that p202-expressing pancreatic cancer cells are less invasive than those without p202 expression. That observation was supported by the findings that p202-expressing tumors showed reduced expression of angiogenic markers, such as interleukin 8 and vascular endothelial growth factor, and p202-expressing pancreatic cancer cells have reduced level of matrix metalloproteinase-2 activity, a secreted protease activity important for metastasis. Importantly, we demonstrated a treatment efficacy by using p202/SN2 liposome complex in a nude mice xenograft model, suggesting a feasibility of using the p202/SN2 liposome in future preclinical gene therapy experiments. Together, our results strongly suggest that p202 expression mediates multiple antitumor activities against pancreatic cancer and may provide a scientific basis for developing a p202-based gene therapy in pancreatic cancer treatment.

Effect of prevention and potentiation of diisopropyl phosphorofluoridate (DFP)-induced delayed neurotoxicity on the mRNA expression of neurofilament subunits in hen central nervous system

Diisopropyl phosphorofluoridate (DFP) is an organophosphorus ester, which produces mild ataxia in 7-14 days and severe ataxia or paralysis in about 20 days (OPIDN) in hens. Previous studies in this laboratory have shown enhanced temporal expression of neurofilament (NF) subunit mRNAs in the spinal cord (SC) of DFP-treated hens. The main objective of this investigation was to study the effect of DFP administration on NF subunit mRNAs expression, when OPIDN is protected or potentiated by pre-treatment or post-treatment, respectively, with phenylmethylsulfonyl fluoride (PMSF). The hens were sacrificed 1, 5, 10, and 20 days after the last treatment. In contrast with enhanced mRNA expression of NF subunits reported in OPIDN, there was no alteration in the expression of NF subunits in the SC of PMSF-protected hens that did not develop OPIDN. PMSF post-treatment of DFP-treated hens, which enhanced delayed neurotoxicity produced by a low dose of DFP, exhibited decrease in the mRNA expression of NF subunits in SC at all time periods (1-20 days) of observation. The expression of NF subunits was also studied in the degeneration-resistant tissue cerebrum of treated hens. The results from protected hens suggested that temporal enhanced expression of NF subunit mRNAs in DFP-treated hens might be contributing to the development of OPIDN in hens. By contrast, PMSF post-treatment seemed to potentiate OPIDN by a mechanism different from that followed by DFP alone to produce OPIDN.

Regulation of interleukin-8 expression by tumor-associated stress factors

Tumor and host cells frequently express interleukin-8 (IL-8). IL-8 has been shown to be motogenic, mitogenic, and angiogenic and to play important roles in human tumor progression. IL-8 expression can be induced by numerous stress factors present in the tumor environment, such as hypoxia, acidosis, hyperglycemia, hyperosmotic pressure, high cell density, hyperthermia, radiation, and chemotherapeutic agents. Understanding the mechanisms of IL-8 expression and regulation will be helpful in designing potential therapeutic modalities targeting IL-8 to control tumor growth and metastasis.

Regulation of interleukin-8 expression by nitric oxide in human pancreatic adenocarcinoma

The regulation of interleukin-8 (IL-8) expression by nitric oxide (NO) was determined in human pancreatic cancer cell lines. CaPan-2 and FG human pancreatic adenocarcinoma cells were incubated for 24 h in medium alone or medium containing a cytokine mixture in the presence or absence of an NO synthase (NOS) inhibitor, N(G)-monomethyl-L-arginine (NMA). The NOS activity and level of IL-8 expression were determined. IL-8 expression was induced in the two cell lines. A low level of NOS activity was detectable only in CaPan-2 cells. Moreover, the presence of NMA did not reverse the induction of IL-8. The FG cells were then engineered to produce a physiologic level of NO and incubated in medium alone or medium containing 1 mM NMA. No significant IL-8 expression was induced in those producing a low level of NO, whereas IL-8 expression was induced in those producing a high level of NO. Inhibition of NO production by NMA reversed this effect. Incubation of FG cells with an NO donor, S-nitroso-D,L.-acetyl-penicillamine (SNAP), led to a concentration-dependent and time-dependent induction of IL-8 expression. This NO-mediated upregulation of IL-8 expression correlated with an increase in IL-8 gene transcription and mRNA stability. Our results indicate that NO is involved in the regulation of IL-8 expression in and contributes to the progression of human pancreatic cancer.

Regulation of vascular endothelial growth factor expression by acidosis in human cancer cells

The influence of acidosis on the expression of the vascular endothelial growth factor (VEGF) gene was determined. FG human pancreatic adenocarcinoma cells were incubated for various time periods in media at a physiologically relevant pH level (6.7-7.4). The expression of VEGF mRNA and protein secretion was inversely correlated with pH in a pH- and time-dependent manner. Transient acidosis also activated the VEGF promoter/enhancer luciferase reporter, which was consistent with an increased VEGF gene transcription rate and VEGF mRNA half-life. These data indicated that acidosis transcriptionally and posttranscriptionally regulates VEGF expression, suggesting that an acidic tumor microenvironment contributes to tumor angiogenesis and progression.

Constitutive Sp1 activity is essential for differential constitutive expression of vascular endothelial growth factor in human pancreatic adenocarcinoma

Vascular endothelial growth factor (VEGF) is a key angiogenic molecule that plays an important role in the growth and metastasis of many types of human cancer, including pancreatic adenocarcinoma. In this study, we explored the regulation of VEGF in human pancreatic cancer cells. Over 70% of the human pancreatic cancer cell lines studied in vitro secreted constitutively high levels of VEGF. High VEGF-secreting cells also generally expressed an elevated steady-state level of VEGF mRNA. Kinetic analysis revealed that the elevated steady-state level of VEGF mRNA was due to enhanced VEGF gene transcription and increased constitutive VEGF promoter activity. Deletive mutation analyses of the VEGF promoter revealed that the region from -109 to -38 bp was essential for constitutive VEGF promoter activity. Further deletion and point mutation analyses indicated that mutation of individual or all of the putative Sp1 binding sites reduced or eliminated the constitutive VEGF promoter activity and abrogated the differential activity of the promoter in high and low VEGF-expressing cells. Consistent with the constitutive VEGF transcription activation, a high level of constitutive Sp1 expression and activity was detected in pancreatic cancer cell lines and pancreatic cancer tissue specimens overexpressing VEGF. Collectively, our data demonstrated that constitutive Sp1 activation is essential for the differential overexpression of VEGF, which in turn plays an important role in the angiogenesis and progression of human pancreatic cancer.

[In vitro study of the killing activities on H-2(d) murine normal and tumor cells by Ly49A gene transfected lymphocytes]

OBJECTIVE

To observe the killing activities of Ly49A gene transfected lymphocytes of C57BL/6 mice to normal and tumor cells of BALB/c mice.

METHODS

pLXSN-Ly49A retrovirus vector was constructed and packaged with PA317 cell line. The lymphocytes of C57BL/6 mice were transfected by culture with virus producing PA317 cells. The Ly49A expression rate on the transfected lymphocytes was detected by flow cytometry and the killing activities of the transfected lymphocytes to normal and tumor cells of BALB/c mice were assayed by MTT method.

RESULTS

The Ly49A expression rates of C57BL/6 mice lymphocytes transfected with pLXSN-Ly49A for 24 hours, of those transfected with pLXSN and nontransfected control were (46.67 +/- 0.35)%, (18.73 +/- 0.85)%, and (19.60 +/- 0.27)%, respectively. The killing activity of the transfected lymphocytes to 4T(1) tumor cells remained almost the same as that of the control (P > 0.05), but to normal fibroblasts decreased sharply (inhibiting rate 22% - 25%).

CONCLUSION

The Ly49A transfected C57BL/6 mice lymphocytes could kill BALB/c mice tumor cells as effectively as the control did, but the activity decreased sharply to normal BALB/c mice cells, which would be instructive for resolving graft versus host disease after allogeneic bone marrow transplantation.

Alteration in cytoskeletal protein levels in sciatic nerve on post-treatment of diisopropyl phosphorofluoridate (DFP)-treated hen with phenylmethylsulfonyl fluoride

Diisopropyl phosphorofluoridate (DFP) is an organophosphorus ester, and a single dose (1.7 mg/kg, sc.) of this compound produces mild ataxia in hens in 7-14 days and a severe ataxia or paralysis (OPIDN) in three weeks. OPIDN is associated with axonal swelling and their degeneration. We have previously observed alteration in neurofilament (NF) protein levels in the spinal cord of DFP-treated hens. The main objective of this investigation was to study NF protein levels in the sciatic nerves (SN) of hens, in which OPIDN has been potentiated by phenylmethylsulfonyl fluoride (PMSF) post-treatment. PMSF is known to protect DFP-treated (1.7 mg/kg) hens from developing OPIDN if injected before, and potentiate OPIDN if injected after the administration of DFP (0.5 mg/kg). The potentiation of OPIDN was accompanied by earlier elevation of NF proteins in the SN particulate fraction. In contrast, SN supernatant fraction showed a transient fall in NF protein levels in potentiation OPIDN. Out of the two other cytoskeletal proteins (i.e., tubulin, tau) studied in this investigation, tubulin also showed earlier elevation in its level in the particulate fraction in potentiated OPIDN. The earlier elevation of NF protein levels in SN particulate fraction in potentiated OPIDN suggested the possible involvement of NFs in delayed neurotoxicity.

[Effects of blood transfusion on cellular immuno-function in patients with laryngeal carcinoma]

OBJECTIVE

To explore the influence of blood transfusion on cellular immunofunction in patient with laryngeal carcinoma.

METHOD

EPICS-XL flow cytometry was used to measure T cell subgroup, NK cell and CD28 in 36 patients with laryngeal carcinoma pre-operation and 2 weeks post-operation. Patients were divided into allotransfusion group and non-transfusion group. Comparison was conducted between the 2 groups.

RESULT

1. Comparison with normal population, decreasing of CD3, CD4, NK cell and CD28 in the 36 patients pre-operation was statistically significant (P < 0.01). 2. Decreasing of CD3, CD4, NK cell and CD28 was statistically significant post-operation (P < 0.05). 3. In the non-transfusion group change of CD3, CD4, CD8, NK cell and CD28 post-operation was statistically insignificant (P > 0.05).

CONCLUSION

While cellular immunofunction is generally low in patients with laryngeal carcinoma, allotransfusion will reduce further. It makes contribution to spreading and metastasis of carcinoma easier.