• A most common endocrine cancer of low incidence is that of the thyroid gland. The cause is associated with very high consumption or deficiency of iodine. Increased incidence of thyroid cancer is observed due to radiation exposure resulting from such events as nuclear accidents or excessive therapeutic radiation.

• The National Cancer Institute reports that the average cumulative thyroid dose of radioactivity to exposed people from the fallout from the Nevada Nuclear tests during the 1950s and 1960s was about 2 rads. Approximately 160 million people in the country at that time were exposed to it. People who lived in heavy fallout areas, children and persons who drank large quantities of milk might have received higher doses of radiation. The limited data on persons exposed as children to I-131 from the nuclear test fallout have provided suggestive bu not conclusive evidence that it is linked to thyroid cancer.

• Estrogen replacement therapy is given to postmenopausal women for various health benefits. But unopposed estrogen increases the risk of uterine (endometrial) cancer. Therefore, progestin is added to the regimen. However, progestin can reduce some of the beneficial effects of estrogen. Correct type of progestin and proper dose is necessary to achieve optimal effect. By using progestin for 10 days or more instead of seven days in sequence, hormone replacement therapy can reduce the uterine cancer risk tremendously. The continuous combined therapy also has the same striking effect.

• Examination of natural antisense RNA/target RNA duplexes in E. coli suggest that the presence of mismatched non-traditional Watson-Crick base pairs in the duplex should be the new direction in the engineering of antisense oligonucleotide drugs.

• Microchromosomes containing the basic functional elements of a chromosome derived from human cells have been fabricated. Though artificial chromosomes have been created over a decade ago using yeast DNA components, producing an artificial human chromosome posed major problems because it is about 100 times larger than the yeast one and very complex. This is very exciting because the idea of correcting genetic defects by simply loading the microchromosome with a gene and delivering it to the target cells is a fantasy for many clinicians.

• Women with ductal carcinoma in situ, an early breast lesion that may develop into invasive cancer, may not benefit from antiestrogen therapy if the lesions are of a subtype that does not need estrogen for growth. This study, performed in an animal model with human tissue, provides for the first time a modality for investigating factors that promote or inhibit ductal carcinoma precancerous lesions.

• Transcriptional control is now the deus ex machina in contemporary cancer research. There is a deeply held tenet that if we succeed in finding a common denominator for gene regulation, all our woes arising from the baffling heterogeneity of malignant growth will be gone. The quest for factors which regulate the regulators is on and attractive; the complexity of the underlying mechanisms is without precedent. Recently, interest in the high-mobility-group (HMG) proteins has been renewed, mainly because of our growing knowledge of transcriptional regulation and the progress in methodology. While it is premature to expect that HMG proteins function as a missing link (or the only one) in protein-DNA recognition, this protein box appears to be of importance both in cancer development and perhaps in therapy.

• Cytokines have evolved into a "unmanageable" family of heterogeneous, low molecular proteins, produced by a variety of cells. They usually act in an intricate, dynamic network, in which individual factors stimulate the production of one or more other factors, which, in turn, cooperate with seemingly unrelated other cell regulators, such a hormones and neuropeptides. Many may function both as agonists and antagonists; some have overlapping activities. As far as the Tumor Necrosis Factors (TNF) are concerned, their terminology soon proved to be a misnomer; while their genes are unmistakeably expressed in various human tumor cells, their role(s) are implicated in a growing number of diseases, ranging from septic shock syndrome, cachexia and AIDS to the pathogenesis of autoimmune diseases. More recently, with the help of methodological advances, attention has turned to the identification of TNF receptors.

• Myb-related proteins are a relatively "new kid on the block", first identified in the v-Myb protein group produced by avian leukemia viruses (AMV and E26) and the c-Myb cellular gene from which they were derived. From these esoteric beginnings, based on in vitro and animal leukemia data, these oncoproteins and their family are being defined in more detail and gradually implicated as one of the key regulators of differentiation as well as of development in perhaps all types of eukaryotes, including vertebrates. Since these proteins are frequently overexpressed or mutated in tumors, they have caught the attention of oncologists.

Glossary

• A glossary of unfamiliar words and jargons in Cancer Watch, August 1997.