Presence of exon 5-deleted oestrogen receptor in human breast cancer: functional analysis and clinical significance

A variant form of the human oestrogen receptor (ER) mRNA lacking sequences encoded within exon 5 has been described (Fuqua SAW, Fitzgerald SD, Chamness GC, Tandon AK, McDonnell DP, Nawaz Z, O'Malloy BW, McGuire WL 1991, Cancer Res 51: 105-109). We have examined the expression of the exon 5-deleted ER (HE delta5) mRNA variant in breast biopsies using reverse transcriptase polymerase chain reaction (RT - PCR). HE delta5 mRNA was present in only 13% of non-malignant breast tissues compared with 32% of carcinomas (95% CI, P=0.05). Presence of the HE delta5 mRNA was associated with the presence of immunohistochemically detected ER (P=0.015) and progesterone receptor (PR) (P=0.02). There was a positive correlation between the presence of HE delta5 and disease-free survival (P=0.05), suggesting that the presence of HE delta5 may be an indicator of better prognosis. We have raised a monoclonal antibody specific to the C-terminal amino acids of HE delta5. This antibody recognized the variant but not the wild-type ER protein. We show that HE delta5 protein is present in breast cancer using immunohistochemical techniques. We also analysed trans-activation by HE delta5 in mammalian cells and showed that, in MCF-7 cells, HE delta5 competes with wild-type ER to inhibit ERE-dependent trans-activation. Our results indicate that this variant is unlikely to be responsible for endocrine resistance of breast cancer, but its presence at both the mRNA and protein level suggest that it may, nevertheless, be involved in regulating the expression of oestrogen-responsive genes in breast cancer.

Persistent gastrointestinal symptoms after correction of malrotation

Persistent vomiting, diarrhoea, or intolerance of feeding, are well recognised problems in children after surgical correction of intestinal malrotation. Conversely, intestinal malrotation is a common accompaniment of chronic idiopathic intestinal pseudo-obstruction. We investigated motor activity of the small intestine during fasting in eight children who had persistent vomiting, intolerance of full enteral feeding, or severe diarrhoea after surgical correction of intestinal malrotation. Abnormality of motor function similar to that found in neuropathic pseudo-obstruction was found in seven of the eight patients. Persistence of symptoms after surgical correction of a malrotation is associated with a motility disturbance which seems to be due to a defect of intrinsic enteric innervation. Such a defect may be important in the aetiology of the malrotation.