Annette Kwon

Mycobacterial infections are critically controlled by interferon-gamma (IFN-gamma) and the cellular responses it elaborates, as shown by patients with mutations in the IFN-gamma receptor ligand-binding chain (IFN-gamma R1) who have disseminated nontuberculous mycobacterial infections. The immunologic sequelae of IFN-gamma R1 deficiency were characterized in 2 unrelated patients from the Indian subcontinent with novel homozygous recessive IFN-gamma R1 mutations. In vitro, these patients' peripheral blood mononuclear cells produced 10% of normal IFN-gamma and interleukin-12 (IL-12) in response to phytohemagglutinin (PHA) but normal amounts of IFN-gamma in response to PHA plus IL-12. Tumor necrosis factor-alpha (TNF-alpha) production was normal in response to endotoxin and to PHA but was not augmented by the addition of IFN-gamma. An abnormal phenotype was not found in heterozygous patient relatives. These patients demonstrate the critical role that the IFN-gamma receptor plays in the regulation of IFN-gamma, IL-12, and TNF-alpha.

Estrogen promotes the proliferation of breast cancer cells. Aromatase is the enzyme that converts androgen to estrogen. In tumors, expression of aromatase is upregulated compared to that of surrounding noncancerous tissue. Tumor aromatase is thought to stimulate breast cancer growth in both an autocrine and a paracrine manner. A treatment strategy for breast cancer is to abolish in situ estrogen formation with aromatase inhibitors. In addition, aromatase suppression in postmenapausal women is being evaluated as a potential chemopreventive modality against breast cancer. One area of aromatase research in this laboratory is the identification of foods and dietary compounds that can suppress aromatase activity. In vitro and in vivo studies have found that grapes and mushrooms contain chemicals that can inhibit aromatase. Therefore, a diet that includes grapes and mushrooms would be considered preventative against breast cancer. Another area of our aromatase research is the elucidation of the regulatory mechanism of aromatase expression in breast cancer tissue. Increased aromatase expression in breast tumors is attributed to changes in the transcriptional control of aromatase expression. Whereas promoter I.4 is the main promoter that controls aromatase expression in noncancerous breast tissue, promoters II and I.3 are the dominant promoters that drive aromatase expression in breast cancer tissue. Our recent gene regulation studies revealed that in cancerous versus normal tissue, several positive regulatory proteins (e.g., nuclear receptors and CREB1) are present at higher levels and several negative regulatory proteins (e.g., snail and slug proteins) are present at lower levels. This may explain why the activity of promoters II and I.3 is upregulated in cancerous tissue. In addition, our in vitro transcription/translation analysis using plasmids containing T7 promoter and the human snail gene as a reporter capped with different untranslated exon Is revealed that exon PII-containing transcripts were translated more effectively than were exon I.3-containing transcripts. An understanding of the molecular mechanisms of aromatase expression between noncancerous and cancerous breast tissue, at both transcriptional and translational levels, may help in the design of a therapy based on suppressing aromatase expression in breast cancer tissue.

Aromatase (CYP19) converts androgens to estrogens. By synthesizing estrogens, aromatase (especially tumor aromatase) is thought to play an important role in promoting breast cancer growth in postmenopausal women. By inhibiting estrogen biosynthesis, aromatase inhibitors, including phytochemicals, are potential chemopreventive agents for breast cancer. Our recent aromatase inhibition experiments have revealed that grape juice contains compounds that inhibit aromatase. Inhibition kinetic analysis indicates that the active components in grape juice inhibit aromatase by competing for the binding of the substrate androstenedione. Results from cell culture experiments suggest that chemicals in grape juice can act as weak agonists/antagonists of estrogen receptor and as aromatase inhibitors. Finally, the breast cancer-protective action of grape juice was demonstrated with a nude mouse model using MCF7aro, an aromatase-transfected MCF-7 cell line. It was found that the tumor size in mice fed (by gavage) with 0.5 ml of grape juice/day for 5 weeks is reduced 70% by comparing to the tumor size in the animals not fed with grape juice. Our finding suggests that grape juice may be useful in breast cancer prevention by inhibiting in situ aromatase/estrogen biosynthesis.

Mycobacterial infections are critically controlled by interferon-g (IFN-g) and the cellular responses it elaborates, as shown by patients with mutations in the IFN-g receptor ligand ‐ binding chain (IFN-gR1) who have disseminated nontuberculous mycobacterial infections. The immunologic sequelae of IFN-gR1 deficiency were characterized in 2 unrelated patients from the Indian subcontinent with novel homozygous recessive IFN-gR1 mutations. In vitro, these patients’ peripheral blood mononuclear cells produced 10% of normal IFN-g and interleukin-12 (IL-12) in response to phytohemagglutinin (PHA) but normal amounts of IFN-g in response to PHA plus IL-12. Tumor necrosis factor-a (TNF-a) production was normal in response to endotoxin and to PHA but was not augmented by the addition of IFN-g. An abnormal phenotype was not found in heterozygous patient relatives. These patients demonstrate the critical role that the IFN-g receptor plays in the regulation of IFN-g, IL-12, and TNF-a.