The NRF-1/α-PAL transcription factor regulates human E2F6 promoter activity

E2F6 is widely expressed in human tissues and cell lines. Recent studies have demonstrated its involvement in developmental patterning and in the regulation of various genes implicated in chromatin remodelling. Despite a growing number of studies, nothing is really known concerning the E2F6 expression regulation. To understand how cells control E2F6 expression, we analysed the activity of the previously cloned promoter region of the human E2F6 gene. DNase I footprinting, gel electrophoretic-mobility shift, transient transfection and site-directed mutagenesis experiments allowed the identification of two functional NRF-1/α-PAL (nuclear respiratory factor-1/α-palindrome-binding protein)-binding sites within the human E2F6 core promoter region, which are conserved in the mouse and rat E2F6 promoter region. Moreover, ChIP (chromatin immunoprecipitation) analysis demonstrated that overexpressed NRF-1/α-PAL is associated in vivo with the E2F6 promoter. Furthermore, overexpression of full-length NRF-1/α-PAL enhanced E2F6 promoter activity, whereas expression of its dominant-negative form reduced the promoter activity. Our results indicate that NRF-1/α-PAL is implicated in the regulation of basal E2F6 gene expression.

Regulation of the alpha-fetoprotein promoter: Ku binding and DNA spatial conformation

This work shows that the proximal promoter of the mouse Afp gene contains a Ku binding site and that Ku binding is associated with down-regulation of the transcriptional activity of the Afp promoter. The Ku binding site is located in a segment able to adopt a peculiar structured form, probably a hairpin structure. Interestingly, the structured form eliminates the binding sites of the positive transcription factor HNF1. Furthermore, a DNAse hypersensitive site is detected in footprinting experiments done with extracts of AFP non-expressing hepatoma cells. These observations suggest that the structured form is stabilised by Ku and is associated with extinction of the gene in AFP non-expressing hepatic cells.

A dose-finding study of lanreotide (a somatostatin analog) in patients with colorectal carcinoma

BACKGROUND. Laboratory data suggest that insulin-like growth factor-1 (IGE-1) may stimulate the growth of different human tumors. At least in acromegalic patients, somatostatin (SMS) analogs, such as lanreotide, suppress the serum levels of growth hormone (GH) and IGE-1. METHODS. To evaluate the tolerability and biologic activity of different doses of lanreotide in patients with advanced colorectal carcinoma, consecutive groups of 3 patients each were subcutaneous treated with lanreotide at doses of 1, 2, 3, 4, 5, or 6 mg three times a day for 2 months. In the event of Grade 3 side effects, 3 additional patients were treated with the same dose before the next dose escalation. Serum samples were obtained on Days 0, 15, 30, and 60 for serum GH, IGF-1, and lanreotide assessment. RESULTS. Twenty-four patients were enrolled and all were evaluable. Except for the 3 and 6 mg doses, for which the observation of a Grade 3 side effect required that an additional three patients be treated, it was sufficient to treat 3 patients at each dose. The overall incidence of side effects was as follows: changes in bowel habits, 83%; abdominal cramps, 79%; diarrhea, 17%; vomiting, 17%; nausea, 21%; steatorrhea, 78%; hyperglycemia, 35%; laboratory hypothyroidism, 39%; gallstones, 13%; and weight loss, 17%. No evidence of an increase in the incidence, intensity, or duration of side effects was observed with dose escalation. Serum IGF-1 levels were as follows: Day 13: 63%, 60%, and 67% of the baseline values for the low (12 mg), intermediate (3-4 mg), and high (5- 6 mg) dose groups, respectively; Day 30: 63%, 59%, and 51%, respectively; and Day 60: 73%, 69%, and 47%, respectively. Serum lanreotide levels declined during treatment in all of the dose groups (90 ng/mL on Day 15, and 35 ng/mL on Day 60 for the 5-6 mg group; 10 ng/mL on Day 15, and 1.5 ng/mL on Day 60 for the 1-2 mg group). No antitumor activity or tumor marker reduction was observed. CONCLUSIONS. No increase in toxicity was observed when subcutaneous lanreotide doses were escalated to 6 mg three times a day for 2 months. The highest doses seemed to maintain reduced serum IGF-1 levels; with the lowest doses, a 'rebound' in serum IGF-1 levels was observed during treatment. Nevertheless, intermittent subcutaneous injections do not ensure constant serum drug concentrations over time.