Effect of difluoromethylornithine on host and tumor polyamine metabolism during total parenteral nutrition

Polyamines as biomarkers of cervical intraepithelial neoplasia

Polyamines (putrescine, spermidine and spermine) play critical roles in cell growth and transformation. Ornithine decarboxylase (ODC), key enzyme in polyamine biosynthesis, is considered a putative protooncogene crucial to the regulation of cell growth and transformation. Cancer patients have elevated levels of polyamines in their physiological fluids compared to normal counterparts. alpha-Difluoromethylornithine (DFMO), a specific suicide inhibitor of ODC, exhibits antitumor and antimetastasis activities, and displays effectiveness in many carcinogen-induced animal chemoprevention models. Therefore, we are using DFMO in a chemoprevention trial for cervical intraepithelial neoplasia grade III (CIN III), and evaluating patients for changes in polyamine metabolism as an intermediate marker of DFMO effect. A preliminary study showed that several milligrams of abnormal cervical biopsy tissue contained detectable levels of ODC activity and polyamines. Additionally, the presence of cadaverine suggested bacterial contamination of these tissues. For this reason, normal and abnormal biopsies collected during colposcopy were rinsed prior to frozen storage. In most patients, abnormal tissue showed greater ODC activities and lower spermidine/spermine ratios than normal tissues. Patients are now being treated with de-escalating doses of DFMO (1-0.06 g/m2/day) for one month. To study the effect of DFMO in patients with CIN III, we are collecting blood and cervical tissue specimens to measure the following parameters: plasma DFMO, ornithine and arginine levels; plasma N1-acetylspermidine levels; erythrocyte (blood polyamine carrier) free polyamine levels; cervical tissue free polyamine levels; cervical tissue N1-acetylspermidine levels; and cervical tissue ODC activities. N1-acetylspermidine will be examined as this compound is known to exist primarily in tumor tissues, not in normal tissues. We therefore established a high-performance liquid chromatography method for N1-acetylspermidine. We expect to find that polyamines are effective markers in analyzing DFMO effects in this chemoprevention trial, thus functioning as pharmacodynamic parameters as well as biomarkers for transformation.

Amelioration of thrombocytopenia with concomitant ornithine in sarcoma-bearing rats receiving high dose difluoromethylornithine

The dose limiting toxicity of difluoromethylornithine (DFMO), when administered by continuous infusion, is thrombocytopenia. DFMO-induced antitumor activity and thrombocytopenia were time- and dose-dependent up to 1700 mg/kg/d when administered continuously for 12 days. Concomitant ornithine administration (at selected molar ratios to DFMO) ameliorated thrombocytopenia induced by DFMO at a dose of 2000 mg/kg/day without adversely affecting its antitumor activity. The purpose of this study was to determine if ornithine could ameliorate the thrombocytopenia of higher DFMO doses and increase the efficacy of DFMO. Fischer 344 male rats with a transplantable sarcoma in the right flank were given 2000 and 3500 mg/kg/d DFMO alone or with ornithine at a molar ratio of 0.4 for 8 days by continuous infusion. Concomitant ornithine infusion overcame the thrombocytopenia that was induced by either dose of DFMO without reducing the antitumor activity against the sarcoma. The antitumor activity, tumor polyamine levels, and tumor S-adenosylmethionine decarboxylase activity did not consistently change with increasing doses of DFMO or with the addition of ornithine to the infusion regimen. These results demonstrate that the thrombocytopenia induced by doses of DFMO greater than 2000 mg/kg/d can be ameliorated without compromising the antitumor activity.

Colorectal ornithine decarboxylase activity in human mucosa and tumors: elevation of enzymatic activity in distal mucosa

To examine the value of ornithine decarboxylase (ODC) assay as a biological marker of potential malignancy in large bowel, we harvested 43 colorectal carcinoma, 7 adenoma, 6 polyps, and 77 normal-appearing mucosa at surgery from patients with colorectal carcinoma. In addition, 13 normal rectal mucosa were obtained at biopsy from patients with benign diseases or diseases unrelated to colorectal carcinoma as normal control. ODC activity was significantly higher in polyps and adenocarcinomas than in normal-appearing mucosa from patients with colorectal carcinoma. ODC activity in normal-appearing mucosa varied throughout the large intestine, with significantly higher activities in the distal segment of the large bowel. The higher ODC activity detected in the sigmoid colon and rectum correlates with the larger incidence of tumor development in this region of the large bowel. This observation needs to be taken into consideration when ODC activities of the colorectal mucosa are measured as biological markers of potential malignancies.

Differential effects of parenteral nutrition on tumor growth and erythrocyte polyamine levels in the rat

The influence of total parenteral nutrition (TPN) on tumor growth and erythrocyte polyamine levels was evaluated in rats with a transplantable fibrosarcoma or a Ward colon tumor. During the experimental periods the fibrosarcoma grows exponentially when rats are fed chow ad libitum while the colon tumor reaches a plateau of its Gompertzian growth curve. A 12-day regimen of TPN resulted in an increased growth of the colon tumor but not the fibrosarcoma. The erythrocyte putrescine levels of fibrosarcoma-bearing rats and the levels of putrescine, spermidine, and spermine of Ward colon-tumor-bearing rats were significantly increased by TPN compared with similarly treated nontumor-bearing (NTB) rats. When the growth of the fibrosarcoma was slowed by feeding a restricted intake (RI) regimen, a subsequent 6-day regimen of TPN resulted in increased tumor growth. Erythrocyte polyamine levels of fibrosarcoma-bearing, RI-rats were elevated by TPN repletion. There was a consistent, significant, interaction between TPN and tumor presence on the erythrocyte putrescine levels in fibrosarcoma-bearing rats and the levels of all polyamines in Ward colon-tumor-bearing rats. The effects of TPN on tumor growth and erythrocyte polyamine levels of tumor-bearing rats may be dependent on the growth characteristics of the tumor. The data demonstrate that TPN consistently enhanced the tumor contribution to the erythrocyte putrescine pool.

Polyamine-directed preferential nutritional repletion of normal tissues in tumor-bearing hosts

Our previous study demonstrated that total parenteral nutrition (TPN) increases erythrocyte (RBC) polyamines selectively in cancer patients but not in non-cancer patients, suggesting that these changes may relate to tumor presence. We therefore studied the possible relationship between RBC polyamine levels and potential tumor growth induced by TPN. In addition, we attempted to control tumor growth during TPN with alpha-difluoromethylornithine (DFMO), a suicide inhibitor of ornithine decarboxylase (ODC), in a fibrosarcoma-bearing rat model. Rats in a control group received chow ad libitum for 3 weeks and their tumors grew exponentially. A restricted intake (RI) tumor-bearing group received 8 g chow per day per rat; this produced malnourished rats in which tumor growth significantly slowed. The third group (RI----TPN) received the RI diet for 2 weeks and TPN for 1 week, which resulted in an increase in tumor growth. The last group (RI----TPN + DFMO) received a 2-week RI regimen and 1-week TPN plus DFMO regimen, which inhibited tumor growth to the level of the RI group due to the addition of DFMO (1 g/kg/day). Although the addition of TPN to the RI regimen markedly increased tumor ODC activity, as well as tumor putrescine and RBC putrescine levels, the addition of DFMO to the RI----TPN regimen entirely abolished these increases. Despite DFMO treatment, liver ODC activity in RI----TPN + DFMO group was unaffected. The plasma albumin level, an indicator of host nutrition, of the RI----TPN + DFMO group was significantly higher than that of the RI group. Liver, spleen, kidney and total body weights of the RI----TPN or RI----TPN + DFMO group were significantly higher than those of the RI group. These results indicate that TPN can enhance tumor growth in malnourished hosts and that the addition of DFMO to TPN can effectively control this TPN-enhanced tumor growth, leading to preferential nutritional repletion of the host.

Influence of total parenteral nutrition on tumor growth and polyamine biosynthesis of fibrosarcoma-bearing rats after induced cachexia

The effect of a protein-free diet (PF) or a restricted intake of chow (RI) and subsequent host repletion with total parenteral nutrition (PF-TPN, RI-TPN) on tumor growth and polyamine metabolism of fibrosarcoma-bearing rats was examined. Host weight was significantly reduced by PF and RI. Tumor growth was reduced in malnourished rats with the PF regimen resulting in the greatest decrease. Rats receiving TPN after 14 days of the RI or PF regimens had higher host weight and plasma albumin levels than malnourished rats. Tumor growth during TPN was evaluated as the percent increase and compared with that of the respective malnourished rats. The percent increase for RI-TPN rats was significantly greater although a trend toward an increase was also evident for PF-TPN rats. Tumor ornithine decarboxylase (ODC) activity and putrescine levels were increased for PF rats and decreased for RI rats while tumor ODC activity was consistently increased by TPN. Tumor growth, ODC activity, and putrescine levels were simultaneously increased only for those rats fed the RI regimen prior to TPN. These results show a disparity in tumor ODC activity, putrescine levels, and tumor growth in malnourished rats. The results of this study suggest that the nutritional origin of cachexia influences the response of the tumor to TPN and emphasizes the importance of considering the methods to induce malnutrition in designing therapuetic regimens.

Ornithine decarboxylase activity in hepatic and extrahepatic metastases from colorectal cancer

The values of ornithine decarboxylase (ODC) activity in hepatic and extrahepatic metastases from primary colorectal cancer were studied. Adjacent noninvolved tissue was used as a control. Liver metastases had significant elevated ODC levels over surrounding liver (0.271 vs. 0.065, respectively, P less than .008). Results similar to those found in liver metastases were noted in extrahepatic metastases (median value, 0.271). This study discusses the possible reasons for these elevations and emphasizes that these differences may have potential roles in the areas of diagnosis, staging, monitoring of the disease, and therapeutic interventions in colorectal cancer and its hepatic and extrahepatic metastases.

Polyamine metabolism in carcinoma of the oral cavity compared with adjacent and normal oral mucosa

In this study, polyamine biosynthesis required for cellular proliferation showed elevated levels in neoplastic cells. Putrescine, spermidine, and spermine, as well as the rate-limiting enzyme ornithine decarboxylase, were measured to evaluate differences in tissue concentration in squamous cell carcinoma of the oral cavity, and in the normal adjacent, buccal, and retromolar trigone tissues. Mean polyamine levels (nanomoles per gram of tissue +/- standard error of the mean) were significantly elevated in tumor tissue at 136 +/- 42 nmol/g for putrescine compared with 41 +/- 9 nmol/g in adjacent, 25 +/- 5 nmol/g in buccal, and 41 +/- 14 nmol/g in retromolar trigone tissues. Tumor spermidine was 415 +/- 41 nmol/g compared with 192 +/- 34 nmol/g in adjacent, 184 +/- 34 nmol/g in buccal, and 214 +/- 63 nmol/g in retromolar trigone tissues. Tumor spermine was 461 +/- 41 nmol/g compared with 236 +/- 30 nmol/g in adjacent, 233 +/- 35 nmol/g in buccal, and 269 +/- 59 nmol/g in retromolar trigone samples. Ornithine decarboxylase activity was highly variable in tumor tissues. High levels of polyamines appear to be specific for this malignancy, whereas ornithine decarboxylase activity is not. Measurement of polyamine content may be useful in evaluating epithelial changes in the oral cavity.