ODC mRNA as a prognostic factor for predicting recurrence in meningiomas

Meningioma recurrence

Meningioma accounts for more than 30% of all intracranial tumours. It affects mainly the elderly above the age of 60, at a female:male ratio of 3:2. The prognosis is variable: it is usually favourable with no progression in tumour grade and no recurrence in WHO grade 1 tumours. However, a minority of tumours represent atypical (grade 2) or anaplastic (grade 3) meningiomas; this heterogeneity is also reflected in histopathological appearances. Irrespective of the grade, the size of the tumour and the localisation may have severe, sometimes lethal consequences. Following neurosurgical interventions to remove the tumour, recurrence and progression in WHO grade may occur. Our knowledge on predisposing histomorphological and molecular factors of recurrence is rather limited. These can be classified as I) demographic II) environmental, III) genetic and epigenetic IV) imaging, V) neuropathological, and VI) neurosurgical. In view of the complex background of tumour recurrence, the recognition of often subtle signs of increased risk of recurrence requires close collaboration of experts from several medical specialties. This multidisciplinary approach results in better therapy and fewer complications related to tumour recurrence.

Epigenetics of Meningiomas

Meningiomas account for one-third of all adult central nervous system tumours and are divided into three WHO grades. In contrast to the relatively well characterized genetic alterations, our current understanding of epigenetic modifications involved in the meningioma-genesis and progression is rather incomplete. Contrary to genetic alterations, epigenetic changes do not alter the primary DNA sequence and their reversible nature serves as an excellent basis for prevention and development of novel personalised tumour therapies. Indeed, growing body of evidence suggests that disturbed epigenetic regulation plays a key role in the pathogenesis of meningiomas. Altered DNA methylation, microRNA expression, histone, and chromatin modifications are frequently noted in meningiomas bearing prognostic and therapeutic relevance. In this review we provide an overview on recently identified epigenetic alterations in meningiomas and discuss their role in tumour initiation, progression, and recurrence.

Ornithine decarboxylase activity as a prognostic marker for colorectal cancer

Ornithine decarboxylase (ODC) is a key enzyme in the biosynthesis of polyamines, which are essential for cell proliferation. ODC activity was measured in 47 colorectal cancer patients, 5 patients with adenoma of colorectum and 4 healthy volunteers. Mean ODC activities of cancer tissue, non-cancerous mucosa from cancer-bearing colorectum, adenoma tissue, and normal mucosa from healthy volunteers were 435+/-392, 154+/-173, 295+/-202, 103+/-60 pmol CO2/h/mg protein, respectively. ODC activity of cancer tissue or adenoma tissue was significantly higher than that of the others. Among colorectal cancer patients, ODC activity in cancer tissue was correlated with T factors, lymph node metastasis and stages. Patients with tumors that had high ODC activity (> or =350 pmol CO2/h/mg protein) showed a poor 10-year survival rate. These results suggest that ODC activity may be a useful marker for patients' prognosis after surgery.

Tissue-based assay for ornithine decarboxylase to identify patients likely to respond to difluoromethylornithine

In a previous publication, we showed that a clinical trial of DL-alpha-difluoromethyl ornithine (DFMO), in combination with PCV (procarbazine, CCNU, vincristine) increased survival of patients with anaplastic gliomas (WHO III) but not glioblastoma multiforme (WHO IV). We believe that treatment outcome (survival) is inversely related to tumor ornithine decarboxylase (ODC) levels. To prove this, we needed to develop an assay to quantify ODC levels in formalin-fixed tumor tissues, which would enable a retrospective study of tumor biopsy specimens from the landmark clinical trial. We developed an assay using a specific polyclonal antibody coupled to an Alexa fluorescent dye. Transgenic MHC-ODC mice with differing levels of ODC in heart muscle were used to establish the relationship between mean gray-scale intensity and enzymatic ODC activity. We found a direct relationship between mean gray-scale intensity of the ODC antibody coupled to Alexa 647 dye and enzymatic activity. Preliminary analysis of a human glioma tissue array shows that tumor-specific variations in levels of ODC can be semiquantitated. We show that mean gray-scale intensity of astrocytoma:glioblastoma is 1:6 and of anaplastic astrocytoma:glioblastoma is 1:4. We also compared the intensity of antibody to Ki67 coupled with phycoerythrin simultaneously in cells but failed to see a relationship that crossed histologies. We conclude that we can measure levels of ODC in formalin-fixed tumor tissue using an antibody to ODC coupled to Alexa 647 dye, and this will enable us to conduct a future study to correlate survival of patients with gliomas of different histologies treated with DFMO to tumor ODC levels.