Herbert I. Jacobson

Smoking, body weight, and early‐stage endometrial cancer

The effect of cigarette smoking on the risk of early‐stage endometrial cancer was evaluated in a population‐based case‐control study of women aged 40 to 69 years from upstate New York. Two hundred women with early‐stage endometrial cancer diagnosed between 1979 and 1981, and 200 matched community controls were interviewed in person and asked about smoking habits and other risk factors. Statistical analysis revealed a significant decline in relative risk with increased smoking (P < 0.05). This effect strongly modified the well‐known increase in risk with body weight. Among smokers risk did not increase with body weight, whereas among nonsmokers risk increased rapidly with body weight, especially among nonsmokers in whom the peripheral conversion of androgens was the primary source of serum estrogen. Despite this apparent reduced risk for endometrial cancer, smoking remains a major health hazard for women as well as men.

A peptide derived from α-fetoprotein prevents the growth of estrogen-dependent human breast cancers sensitive and resistant to tamoxifen

An 8-mer peptide (EMTOVNOG) derived from α-fetoprotein was compared with tamoxifen for activity against growth of human breast cancer xenografts implanted in immune-deficient mice. Both peptide and tamoxifen prevented growth of estrogen-receptor-positive MCF-7 and T47D human breast cancer xenografts. A subline of MCF-7, made resistant to tamoxifen by a 6-month exposure to this drug in culture, was found to be resistant to tamoxifen in vivo. Peptide completely prevented the xenograft growth of this tamoxifen-resistant subline of MCF-7. Neither peptide nor tamoxifen was effective in slowing the xenograft growth of the estrogen-receptor-negative MDA-MB-231 human breast cancer. A worrisome side effect of tamoxifen is its hypertrophic effect on the uterus. In this study, tamoxifen was shown to stimulate the growth of the immature mouse uterus in vivo, and the peptide significantly inhibited tamoxifens uterotrophic effect. The mechanism of action of peptide is different from that of tamoxifen in that the peptide does not interfere with the binding of [3H]estradiol to the estrogen receptor. In conclusion, α-fetoprotein-derived peptide appears to be a novel agent that interferes with the growth of tamoxifen-sensitive as well as tamoxifen-resistant estrogen-receptor-positive human breast cancers; it inhibits the uterotrophic side effect of tamoxifen and, thus, it may be useful in combination with or in place of tamoxifen for treatment of estrogen-receptor-positive human breast cancers.

Alpha-fetoprotein-derived antiestrotrophic octapeptide.

Alpha-fetoprotein (AFP) is a major serum protein produced during fetal development. Experimental findings suggest that AFP has antiestrotrophic activity and that it can be developed as a therapeutic agent to treat existing estrogen-dependent breast cancer or to prevent premalignant foci from developing into breast cancer. The antiestrotrophic activity of AFP was reported to be localized to a peptide consisting of amino acids 447-480, a 34-mer peptide termed P447. A series of parsings and substitutions of amino acids in the P447 sequence was intended to identify the shortest analog which retained antiestrotrophic activity. Peptides related to P447 were generated using solid phase peptide synthesis. Several shorter peptides, including an 8-mer called P472-2 (amino acids 472-479, peptide sequence EMTPVNPG), retained activity, whereas peptides shorter than eight amino acid residues were inactive. The dose-related antiestrotrophic activity of AFP-derived peptides was determined in an immature mouse uterine growth assay that measures their ability to inhibit estradiol-stimulated uterine growth. In this assay, the maximal inhibitory activities exhibited by peptide P472-2 (49%), by peptide P447 (45%), and by intact AFP (35-45%) were comparable. The octapeptide P472-2 was also active against estradiol-stimulated growth of T47D human breast cancer cells in culture. These data suggest that peptide P472-2 is the minimal sequence in AFP, which retains the antiestrotrophic activity found with the full-length molecule. The synthetic nature and defined structure of this 8-mer peptide suggest that it can be developed into a new drug which opposes the action of estrogen, perhaps including the promotional effects of estradiol in the development of human breast cancer.

Similarity between natural and recombinant human alpha-fetoprotein as inhibitors of estrogen-dependent breast cancer growth.

Alpha-fetoprotein (AFP) isolated from rodent amniotic fluid orhuman cord sera, upon incubation with a molarexcess of estradiol, is converted to a formwhich inhibits estrogen-stimulated tissue growth. The purpose ofthis study was to determine whether recombinant humanAFP produced in an E. coli expression systemretained this function. The recombinant protein was similarto the natural protein isolated from pooled humancord sera in all functional aspects evaluated. Itwas detected by monoclonal and polyclonal antibodies tothe natural protein. Following exposure to estradiol, itwas converted to an inhibitor of estrogen-stimulated growthof immature mouse uterus yielding a dose/response curvesimilar to that of the natural protein. Itinhibited the growth of estrogen-dependent (MCF-7) but notestrogen-independent (MDA-MB-231) breast cancer xenografts with the sameschedule dependency and resultant histological changes as thenatural protein. Availability of large quantities of homogeneous,biologically active recombinant human AFP will facilitate furtherstudies of structure/function, mechanism, and therapeutic potential ofthis agent as a regulator of breast cancergrowth.

Estrogen and progesterone receptors in hereditary hemorrhagic telangiectasia.

Hereditary hemorrhagic telangiectasia (HHT) often requires transfusion and has major ill-effects. The recent literature reports successful high-dose estrogen treatment of epistaxis caused by HHT. To investigate this, biopsy specimens taken from areas clinically involved with telangiectasia in four patients were evaluated for estrogen- and progesterone-binding receptors. Specimens from two women (ages 34 and 38) were positive for both estrogen and progesterone receptors in ranges observed in breast carcinoma specimens. Specimens from two men (ages 34 and 78) were positive only for progesterone receptors at lower but clearly detectable levels of activity. Nasal mucosa specimens from control patients −2 male and 4 female – yielded no detectable levels of estrogen or progesterone receptors. Because of the side effects of high-dose estrogen (especially in males), we have initiated systemic progesterone therapy with both megestrol acetate and medroxyprogesterone acetate. Marked diminution in epistaxis incidence and severity was observed in three patients after initial systemic progesterone treatment. All treated patients have been maintained with good epistaxis control for over 1 year.

Purification of alpha-fetoprotein from human cord serum with demonstration of its antiestrogenic activity.

Alpha-fetoprotein (AFP) was purified from pooled human cord serum to determine whether it would be similar to purified mouse AFP in its ability to be transformed into an antiestrogen by incubation with estradiol (E2). Greater purity was attained with a three-step purification procedure of chromatofocusing, Blue-Sepharose chromatography and immunoaffinity chromatography than with a two-step procedure of polyacrylamide gel electrophoresis followed by Blue-Sepharose chromatography. Nevertheless, both procedures rendered AFP in a form that was transformable by E2 to an antiestrogen, although the product of the three-step procedure afforded more consistent biological activity. Removal of albumin from AFP was crucial for transformation of AFP to an antiestrogen. Thus, human AFP is similar to mouse AFP in being transformed to an antiestrogen upon incubation with E2, even though there is only 66% structural homology between the two proteins, and human AFP lacks the high-affinity binding site for E2 present in the mouse AFP molecule.

Estrogen receptor in human endometrium during the menstrual cycle and early pregnancy

Abstract Available estrogen receptor has been estimated in endometrial tissue obtained from 8 women on the eighth and twenty-first days of the same menstrual cycle. Respective concentrations were 3.8 ± 1.1 and 6.0 ± 2.5 femtomoles (fmoles) per milligram of wet tissue during 5 ovulatory cycles and were 8.1 ± 3.7 and 2.9 ± 0.3 fmoles per milligram during 3 anovulatory cycles. The latter cycles appear to be associated with elevated endometrial receptor concentration on Day 8, and a marked drop between Days 8 and 21. In decidual tissue obtained from 4 patients who were 9 to 18 weeks pregnant, receptor concentration is low. The data indicate that available receptor concentration in human endometrium changes with hormonal status.

AFPep: an anti-breast cancer peptide that is orally active.

SummaryBackgroundWe have synthesized a cyclic nonapeptide (AFPep) that is effective, after being administered by parenteral routes, for the treatment or the prevention of breast cancer. To test the hypothesis that AFPep remains safe and efficacious after oral administration, three different whole-animal bioassays were utilized, and the mechanism by which AFPep functions was investigated.MethodsUsing a human breast cancer xenograft model in mice for therapeutic activity, a carcinogen-induced breast cancer model in rats for prevention efficacy, and a mouse uterus growth inhibition model of anti-estrogenic activity, AFPep was administered by oral gavage (p.o.) and its effects compared to those following intraperitoneal (i.p.) and subcutaneous (s.c.) administration. Toxicity studies evaluated body weights and organ weights in mice and rats receiving AFPep. Preliminary mechanistic studies were carried out in T47D human breast cancer cells growing in culture and evaluated the effect of AFPep on estrogen-stimulated cell growth, phosphorylation of the estrogen receptor (ER), and on level of ER-related kinases.ResultsOrally administered AFPep stopped the growth of human tumor xenografts in mice, decreased the incidence and multiplicity of breast cancers in carcinogen-exposed rats, and inhibited the estrogen-stimulated growth of mouse uteri. In each of these systems, orally administered AFPep produced an effect similar to that obtained for AFPep administered by either i.p or s.c. routes. In rodents, no evidence of toxicity was seen for the peptide, even at very high doses. In culture, AFPep inhibited the estrogen-stimulated growth, but not the basal growth, of T47D cells, and it inhibited the estrogen-stimulated phosphorylation of Serine 118 in the ER of these cells, which was not explainable by early changes in ER-related kinases.ConclusionsChronic oral administration of AFPep appears to be safe and effective for the treatment or prevention of breast cancer in animal models.

Prevention of N-Methyl-N-Nitrosourea–Induced Breast Cancer by α-Fetoprotein (AFP)–Derived Peptide, a Peptide Derived from the Active Site of AFP

Purpose: α-Fetoprotein (AFP) is a protein of pregnancy associated with a decrease in lifetime risk of breast cancer in parous women. A synthetic, cyclic nonapeptide has been developed that mimics the antioncogenic active site of AFP. To test the hypothesis that the AFP-derived peptide (AFPep) can prevent breast cancer, the N-methyl-N-nitrosourea–induced breast cancer model was used in rats. Experimental Design: AFPep was given daily by injection beginning 10 days after N-methyl-N-nitrosourea treatment and continued for 23 days (a time designed to mimic pregnancy) or for other times to assess efficacy as a function of drug duration. Tumor incidence, multiplicity, and latency were noted as end points. At necropsy, pathology analysis of tumors and major organs were obtained. Results: AFPep prevented cancer in a dose-dependent fashion. Significantly longer mean tumor-free days (P < 0.02), lower tumor incidence (P = 0.004), and lower tumor multiplicity were observed for AFPep-treated groups. No evidence of host toxicity as measured by body weight, cage activity, fur texture, and organ weights (liver, uterus, heart, kidney, and spleen) were found in animals treated with AFPep. Mechanistic studies using transplantable human breast cancer xenografts showed that the peptide interfered with estrogen-dependent breast cancer growth inhibited the phosphorylation of the estrogen receptor and activated phosphorylation of p53. Conclusions: AFPep is a well-tolerated, mechanistically novel, chemopreventive agent in models of breast cancer and warrants further development for the prevention and treatment of this disease in humans.

The recombinant third domain of human alpha-fetoprotein retains the antiestrotrophic activity found in the full-length molecule

Previous studies have shown that alpha-fetoprotein (AFP) interferes with estrogen (E2)-stimulated growth, including E2-stimulated breast cancer growth. In an effort to localize the antiestrotrophic portion of the molecule, the C-terminal one-third (200 amino acids) of human AFP, known as Domain III, was produced in a baculovirus expression system as a fusion protein containing an amino terminal histidine tag. The histidine tag was included to facilitate purification by metal ion affinity chromatography. The purified recombinant Domain III fusion protein was functionally similar to full-length natural AFP isolated from human cord sera or from cultured human hepatoma cells (HepG2) in that they all produced significant and quantitatively similar inhibition of E2-stimulated growth of immature mouse uterus. Furthermore, the dose-response profiles of the recombinant Domain III AFP and natural full-length AFP were similar. Preincubation of either protein in a molar excess of E2 lowered the minimally effective antiestrotrophic dose and produced a difference spectrum consistent with a change in conformation. These findings indicate that the antiestrotrophic activity of AFP is contained within the third domain of the molecule, and they have obvious implications for the production of biologically active peptides derived from this portion of the AFP molecule.