Deoxyglucose kinetics in a rat brain tumor

Modulatory Role of Shorea robusta Bark on Glucose-metabolizing Enzymes in Diethylnitrosamine Induced Hepatocellular Carcinoma in Rats

Introduction:

The modulations of glucose-metabolizing enzyme activities play a vital rolein the depletion of energy metabolism and leads to inhibition of cancer growth.

Objective:

To find the effect of shorearobusta bark extract on glucose-metbolizing enzymes in diethylnitrosamine (DEN) induced hepatocellular carcinoma rats.

Materials and Methods:

Biochemical evaluation of glucose metabolizing enzyme were done in before and after shorearobusta bark extract (500mg/kg) treatment in DEN induced rats.

Results:

A significant increasein the activities of the key glycolytic enzymes viz., hexokinase and phosphoglucoisomerase, with a significant decrease in the gluconeogenic enzymes glucose-6-phosphatase and fructose-1,6-bisphosphatasewere observed in HCC bearing rats, when compared with the control. Administration of shorearobusta extract caused a significant decrease in theactivities of glycolytic enzymes and an increase in the gluconeogenic enzymes activities to near normal values.

Conclusion:

The current findings suggest that the S. robusta extract has a definite modulating role on the key enzymes ofglucose-metabolism in HCC. The modulatory effect may be due to the phytoactive constituents present in the extract of S. robusta.

SUMMARY

Administration of shorea robusta bark extract caused a significant decrease in the activities of glycolytic enzymes and an increase in the gluconeogenic enzymes activities to near normal values. The S. robusta extract has modulatory activity on the carbohydrate metabolism in DEN-induced HCC bearing rats through a mechanism that which does not provoke any acute biochemical disturbances in the metabolic pathways of glycolysis and gluconeogenesis. The modulatory effect of S. robusta extract may be attributed to the presence of active compounds such as polyphenols and flavonoids.

Abbreviations used: HCC: Hepatocellular Carcinoma, SRBE: Shorearobusta bark extract; HEX: Hexokinase; PGI: Phosphoglucoisomerase; DEN: Diethylnitrosamine.

Myrtenal ameliorates diethylnitrosamine-induced hepatocarcinogenesis through the activation of tumor suppressor protein p53 and regulation of lysosomal and mitochondrial enzymes

Myrtenal is a novel class of compound belongs to monoterpenes found predominantly in mint, pepper, etc., and it was shown to have excellent pharmacological activities against many diseases among which cancer is imperative. Hepatocellular carcinoma is a primary malignancy of the hepatocytes, which rapidly leads to death in short periods. The aim of this study was to investigate the possible therapeutic efficiency of myrtenal against diethylnitrosamine-induced experimental hepatocarcinogenesis by analyzing the key enzymes of carbohydrate metabolism, lysosomal and mitochondrial TCA cycle enzymes, and also the possible role of tumor suppressor protein p53, and scanning electron microscopic studies. The results revealed that myrtenal significantly ameliorated the altered enzymes of carbohydrate metabolism, lysosomal and mitochondrial enzymes, and interestingly the tumor suppressor protein p53 was found to be significantly accumulated in myrtenal-treated animals, which inevitably confirms that myrtenal has a prominent role in preventing the liver cancer during treatment. Furthermore, the antineoplastic property was well evidenced by the mRNA expression of p53 protein by the reverse-transcriptase polymerase chain reaction and immunoblot analysis. The observed anticancer property of myrtenal may be due to the involvement and expression of p53 and influence in the mitochondrial and lysosomal membrane integrity and also interference in the gluconeogenesis process of cancer cells. Our results suggest that myrtenal is very efficient and useful compound in the treatment of liver cancer in future.

Potential role of sugar transporters in cancer and their relationship with anticancer therapy

Sugars, primarily glucose and fructose, are the main energy source of cells. Because of their hydrophilic nature, cells use a number of transporter proteins to introduce sugars through their plasma membrane. Cancer cells are well known to display an enhanced sugar uptake and consumption. In fact, sugar transporters are deregulated in cancer cells so they incorporate higher amounts of sugar than normal cells. In this paper, we compile the most significant data available about biochemical and biological properties of sugar transporters in normal tissues and we review the available information about sugar carrier expression in different types of cancer. Moreover, we describe the possible pharmacological interactions between drugs currently used in anticancer therapy and the expression or function of facilitative sugar transporters. Finally, we also go into the insights about the future design of drugs targeted against sugar utilization in cancer cells.

Therapeutic potential of riboflavin, niacin and ascorbic acid on carbohydrate metabolizing enzymes in secondary endometrial carcinoma bearing rats

Curative potential of riboflavin, niacin and ascorbic acid against tamoxifen mediated endometrial carcinoma was established by studies on carbohydrate metabolizing enzymes. The enzymes investigated were glycolytic enzymes namely, hexokinase; aldolase; phosphoglucoisomerase and the gluconeogenic enzymes namely, glucose-6-phosphatase and fructose-1, 6-biphosphatase in endometrial carcinoma bearing rats. A significant increase in glycolytic enzymes and a subsequent decrease in gluconeogenic enzymes were observed in plasma, liver and kidney of endometrial carcinoma animals. The administration of riboflavin (45 mg/kg bw/day), niacin (100 mg/kg bw/day) and ascorbic acid (200 mg/kg bw/day) along with tamoxifen (45 mg/kg bw/day) caused a significant decrease in the activity of glycolytic enzymes and a significant increase in the activities of gluconeogenic enzymes to near normal levels in experimental animals. Our results suggest that riboflavin, niacin and ascorbic acid have potential combination therapy against tamoxifen mediated secondary endometrial carcinoma in experimental rats. However, there were no deleterious side effects observed in combinants alone treated animals.

[18F]FDG uptake and PCNA, Glut-1, and Hexokinase-II expressions in cancers and inflammatory lesions of the lung

PURPOSE

The aim of this study was to evaluate the relationships among [18F]fluorodeoxyglucose ([18F]-FDG) uptake, Glut-1 and HK-II expressions, and grade of inflammation in resected lung lesions.

MATERIALS AND METHODS

Sixty patients had undergone preoperative 18F-FDG-PET imaging and thoracotomy. For semiquantitative analysis of 18F-FDG uptake, partial volume effect corrected maximum standardized uptake values (pSUVs) were calculated. Immunohistochemical staining was performed in resected specimens using anti-Glut-1, anti-HK-II, and anti-proliferative cellular nuclear antigen (PCNA) antibodies, and immunoreactivities were scored as G-, H-, and P-indexes on a five-point scale (0: 0%; 1: 20%, 2: 40%; 3: 60%; 4: 80%, and 5: 100% percentages of strongly immunoreactive cells).Grade of inflammation was also evaluated.

RESULTS

The malignant lesions had higher pSUV and higher G- and H- than nonmalignant lesions. pSUVs correlated with the G- (p < .001), H- (p < .01), and P-indexes (p < .01) in malignant lesions. In adenocarcinomas, cancers with lower differentiation showed higher expression of Glut-1 and HK-II than those with higher differentiation. A positive linear regression was observed between pSUVs and the grading of inflammation in nonmalignant lesions (p < .05).

CONCLUSIONS

Our study indicates that 18F-FDG uptake in lung cancer correlates well with the Glut-1, HK-II, and PCNA expression. For nonmalignant lesions, the presence of a higher inflammatory process correlated with 18F-FDG uptake.

Comparison of [18F]fluorodeoxyglucose uptake with glucose transporter-1 expression and proliferation rate in human glioma and non-small-cell lung cancer

To clarify the biological significance of [18F]fluorodeoxyglucose (18F-FDG) accumulation in patients with cancer, we assessed the relationships between 18F-FDG uptake and glucose transporter-1 (GLUT-1) expression and proliferation rate in human glioma and lung cancer. We obtained FDG PET images and measured standardized uptake values (SUVs) of primary tumours in 13 patients with brain glioma and 25 patients with non-small-cell lung cancer. After surgery, portions of respected tumours were obtained, and the proliferation rate was measured as proliferation index (per cent of (S+G2+M)/(G0+G1+S+G2+M)) using DNA flow cytometry. The expression of GLUT-1 in a tumour was evaluated by using immunostaining. We classified GLUT-1 expression as grade 0 (no positive cell), grade 1 (< 10% cells positive), grade 2 (11-50% cells positive) and grade 3 (51-100% cells positive). Based on the expression of GLUT-1, cases with grades 0, 1, 2 and 3 showed SUVs of 6.1 +/- 2.8, 5.0 +/- 3.2, 8.3 +/- 3.3 and 10.4 +/- 6.6, respectively (P < 0.05). Non-small-cell lung cancer showed higher FDG uptake (SUV, 8.5 +/- 5.1) and higher GLUT-1 expression (grade, 2.0 +/- 1.0) than did brain glioma (SUV, 4.7 +/- 2.5; grade, 0.8 +/- 0.8). Based on the total number of cases, SUVs did not relate to proliferation index (r = 0.19). In non-small-cell lung cancer, SUVs did not correlate with proliferation index, whereas in glioma, SUVs were strongly related to proliferation index (r = 0.79, P < 0.01). In conclusion, FDG uptake generally correlated with GLUT-1 expression in non-small-cell lung cancer and glioma. In the case of glioma, FDG uptake also indicated increased cellular proliferation, which was not demonstrated in non-small-cell lung cancer.

Recuperative effect of Semecarpus anacardium linn. nut milk extract on carbohydrate metabolizing enzymes in experimental mammary carcinoma-bearing rats

Semecarpus anacardium Linn. of the family Anacardiaceae has many applications in the Ayurvedic and Siddha systems of medicine. We have tested the antitumour activity of Semecarpus anacardium nut extract against experimental mammary carcinoma in animals. As there is a direct relationship between the proliferation of tumour cells and the activities of the glycolytic and gluconeogenic enzymes, we studied changes in the activities of enzymes involved in this metabolic pathway in the liver and kidney. The enzymes investigated were glycolytic enzymes, namely hexokinase, phosphoglucoisomerase, aldolase and the gluconeogenic enzymes, namely glucose-6-phosphatase and fructose-1,6-biphosphatase in experimental rats. A significant rise in glycolytic enzyme activities and a simultaneous fall in gluconeogenic enzyme activities were found in mammary carcinoma bearing rats. Drug administration returned these enzyme activities to their respective control activities.

Pheochromocytomas: imaging with 2-[fluorine-18]fluoro-2-deoxy-D-glucose PET

PURPOSE

To assess the sensitivity of positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in pheochromocytomas and, secondarily, to compare images obtained with FDG PET to those obtained with metaiodobenzylguanidine (MIBG) scintigraphy.

MATERIALS AND METHODS

Twenty-nine patients with one or more known or subsequently proved pheochromocytomas underwent FDG PET (35 scans) and MIBG scintigraphy (35 scans). Tumor uptake of FDG was quantified on positive PET scans.

RESULTS

Tumor uptake of FDG was detected in 22 of 29 patients. Most benign (seven of 12 patients) and most malignant (15 of 17 patients) pheochromocytomas and their metastases avidly concentrated FDG. In four patients whose pheochromocytomas failed to accumulate MIBG, uptake of FDG in the tumors was intense. For the majority of the 16 patients whose tumors concentrated both agents, however, ratings for MIBG images compared to FDG PET images for delineation of the tumor in comparison to background and normal organ accumulation were superior for nine patients (56%) and as good or better for 14 (88%).

CONCLUSION

Most pheochromocytomas accumulate FDG. Uptake is found in a greater percentage of malignant than benign pheochromocytomas. FDG PET is especially useful in defining the distribution of those pheochromocytomas that fail to concentrate MIBG.

PET FDG studies of Wilms tumors

PURPOSE

Wilms tumor is the most common renal neoplasm in children. The diagnosis is usually suggested by anatomic imaging and established by biopsy or resection. The principal roles of functional imaging have been the search for skeletal metastases and evaluation of renal function. We hypothesized that, like many tumors, Wilms tumors could concentrate 18F-FDG and that evaluation of the metabolic activity of these neoplasms might prove clinically useful.

MATERIALS AND METHODS

Three patients with known or suspected Wilms tumors underwent positron emission tomography (PET) with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) scanning (four scans). A patient with a single Wilms tumor was studied once at the time of diagnosis. The two patients with bilateral Wilms tumors were studied during therapy.

RESULTS

Uptake of FDG was present in the Wilms tumor studied at diagnosis, and in one of the tumors in each of the patients with bilateral disease studied during therapy. In all three cases, the results of the PET scans influenced therapeutic decisions.

CONCLUSION

PET FDG scanning may be useful for the management of selected patients with Wilms tumors.

In vivo effects of insulin on tumor and skeletal muscle glucose metabolism in patients with lymphoma

BACKGROUND

The anabolic properties of insulin have been suggested for use to reverse malnutrition associated with cancer. The host and tumor sensitivities to insulin are critical for such treatments, which aim to improve patient nutrition. The authors studied insulin effects on tumor and skeletal muscle metabolism with 2-[18F]-fluoro-2-deoxy-D-glucose ([18F]FDG) and positron emission tomography (PET).

METHODS

Six patients with lymphoma twice underwent [18F]FDG-PET imaging: once after fasting overnight and once during euglycemic hyperinsulinemic clamp. The dynamic uptake of the glucose analogue [18F]FDG was measured in diseased nodes and upper arm skeletal muscle in both metabolic states. The [18F]FDG uptake in muscle and the whole body glucose use during euglycemic hyperinsulinemic clamp were compared with those of weight-matched healthy subjects studied under similar circumstances.

RESULTS

In lymphomatous tissue, [18F]FDG uptake rates were similar in overnight fasting and euglycemic hyperinsulinemic clamp (38 +/- 10 versus 41 +/- 9 mumol/100 g/minute, not significant), whereas glucose uptake in skeletal muscle was increased by insulin (1.7 +/- 0.2 versus 3.8 +/- 0.5 mumol/100 g/minute, P = 0.012). Both basal (2.3 +/- 0.2 mumol/100 g/minute, P = 0.061) and insulin-stimulated (8.5 +/- 1.9 mumol/100 g/minute, P = 0.055) skeletal arm muscle glucose uptake rates were higher in control subjects than in patients. Whole body glucose use was 55% lower in patients than in control subjects (17 +/- 3 mumol/kg/minute versus 38 +/- 3 mumol/kg/minute, P = 0.002), consistent with insulin resistance in cancer.

CONCLUSIONS

We found that insulin does not induce major changes in glucose uptake of lymphomatous tissue. Although insulin sensitivity of skeletal muscle was also reduced in patients with lymphoma, the net insulin effect may counteract imbalance between glucose uptake of tumor and muscle, offering a potential means to circumvent at least some metabolic abnormalities found in cancer.

Overexpression of Glut-1 glucose transporter in human breast cancer. An immunohistochemical study

BACKGROUND

Breast cancers have higher than normal glucose metabolism, but the mechanism of glucose entry into these tumors is not well understood.

METHODS

The expression of five facilitative glucose transporters, Glut-1 (erythrocyte type), Glut-2 (liver type), Glut-3 (brain type), Glut-4 (muscle/fat type), and Glut-5 (small intestine type), was studied by immunohistochemistry of paraffin sections from 12 primary human breast cancers and 8 lymph node metastases from 2 patients. Rat tissues known to express these glucose transporters were used as controls.

RESULTS

All the primary breast cancers and the lymph node metastases were positive for Glut-1. This transporter was expressed on the cell membrane and in the cytoplasm of the tumor cells, but exhibited marked intratumoral and intertumoral variability in the proportions of positive cells and the intensity of staining. Staining of the normal mammary epithelium, if present, was much lower than observed in tumor cells from the same patient. Glut-2 was expressed in all of the tumors, but the intensity of staining was not consistently stronger than that seen in healthy breast. Clusters of Glut-4-positive granule were observed in cells in six of the tumors. None of the tumors or the healthy breast in the tissues studied expressed Glut-3 or Glut-5.

CONCLUSIONS

Higher expression of the glucose transporter Glut-1 by breast cancer cells compared with the healthy breast tissue is common. Increased glucose transporter protein expression may contribute to the increased uptake of 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) by these tumors observed by positron emission tomography (PET) imaging.

Overexpression of Glut-1 glucose transporter in human breast cancer. An immunohistochemical study

BACKGROUND

Breast cancers have higher than normal glucose metabolism, but the mechanism of glucose entry into these tumors is not well understood.

METHODS

The expression of five facilitative glucose transporters, Glut-1 (erythrocyte type), Glut-2 (liver type), Glut-3 (brain type), Glut-4 (muscle/fat type), and Glut-5 (small intestine type), was studied by immunohistochemistry of paraffin sections from 12 primary human breast cancers and 8 lymph node metastases from 2 patients. Rat tissues known to express these glucose transporters were used as controls.

RESULTS

All the primary breast cancers and the lymph node metastases were positive for Glut-1. This transporter was expressed on the cell membrane and in the cytoplasm of the tumor cells, but exhibited marked intratumoral and intertumoral variability in the proportions of positive cells and the intensity of staining. Staining of the normal mammary epithelium, if present, was much lower than observed in tumor cells from the same patient. Glut-2 was expressed in all of the tumors, but the intensity of staining was not consistently stronger than that seen in healthy breast. Clusters of Glut-4-positive granule were observed in cells in six of the tumors. None of the tumors or the healthy breast in the tissues studied expressed Glut-3 or Glut-5.

CONCLUSIONS

Higher expression of the glucose transporter Glut-1 by breast cancer cells compared with the healthy breast tissue is common. Increased glucose transporter protein expression may contribute to the increased uptake of 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) by these tumors observed by positron emission tomography (PET) imaging.

Two-stage resuscitation of the cat brain after prolonged cardiac arrest

Following prolonged cardiac arrest, reperfusion of the brain is endangered by the low blood perfusion pressure during the early resuscitation phase. In order to avoid low perfusion brain injury, a two-stage resuscitation protocol was applied to cats submitted to 30 min potassium chloride induced cardiac arrest: first, the heart was resuscitated, followed--after stabilisation of blood pressure--by recirculation of the brain. During cardiac resuscitation the brain was disconnected from the general circulation by inflating a pneumatic cuff around the neck. The results were compared with the outcome of conventional one-stage resuscitation following 15 min cardiac arrest. Cardiac resuscitation was successful in 5 out of 8 animals with 15 min and in 6 out of 13 animals with 30 min cardiac arrest. In successfully resuscitated animals of both groups, brain energy metabolism recovered to normal within 3 h although two-stage resuscitation increased brain ischemia time to 37-61 min. Two-stage resuscitation, in consequence, is a promising approach for revival of the brain after prolonged cardiac arrest.

18F-2-deoxy-2-fluoro-D-glucose uptake into human tumor xenografts. Feasibility studies for cancer imaging with positron-emission tomography

The positron-emitting glucose analogue 18F-2-fluoro-2-deoxy-d-glucose (FDG) was evaluated for its accretion into the following subcutaneous human tumor xenografts in nude mice: B-cell lymphoma (Namalwa or Raji), ovarian carcinoma (HTB77), colon cancer (SW948), choriocarcinoma (BEWO), bladder cancer (UM-UC-2), renal cell carcinoma (UM-RC-3), neuroblastoma (Mey), melanoma (HTB63), and small cell lung carcinoma (NCI69). Two hours postinjection, tumor uptakes ranged from 0.027 (colon cancer) to 0.125% kg injected dose/g (melanoma); and was greater than 0.085 in the Namalwa lymphomas and the renal cell carcinomas. Tumor-blood ratios of up to 23:1 were seen 2 hours postinjection (melanoma) with a mean tumor-blood ratio for all tumors of 12.3 +/- 1.8. Uptake in the other tumors was intermediate. When evaluated, tumor uptake was slightly greater at 1 than at 2 hours postinjection, although target-background ratios were generally higher at 2 hours postinjection. This compound, FDG, may have broad applicability as a tracer for positron-emission tomographic imaging of many human malignancies.

Deoxyglucose lumped constant estimated in a transplanted rat astrocytic glioma by the hexose utilization index

The lumped constant (LC) for calculating the regional glucose (glc) metabolic rate by the deoxyglucose (DG) method was estimated in a transplanted rat glioma and normal rat brain. First, the hexose utilization index (HUI) was measured at 1.5, 3.0, and 4.5 min in right hemisphere glioma implants and uninvolved contralateral hemisphere following bolus intravenous injections of [3H]DG and [14C]glucose. At these times, the glioma HUI values were 0.639, 0.732, and 0.712, respectively, and the coordinate left hemisphere values were 0.432, 0.449, and 0.418. Second, the volumes of distribution of DG and glucose were determined to be 0.436 and 0.235 in glioma implants and 0.402 and 0.237 in left hemisphere, respectively. Third, following simultaneous intracarotid injections of [3H]DG and [14C]glucose, the ratio K1/K1 was 1.1 in glioma grafts and 1.3 in left hemisphere. With these values for HUI, volume of distribution, and K1 ratio, the LC in this rat glioma was estimated to be 2.1 times higher than the left hemisphere LC (p less than 0.02). These results suggest that measurement of brain tumor CMRglc using a normal brain LC may significantly overestimate the true tumor CMRglc.