Breast cancer cells cultured in a system of new design presecrete an extracellular matrix and proliferate within it without cell-cell adhesion

Breast cancer cells, MCF-7 line, when cultured in microporous, hydrophobic polymer tubes, presecrete ribbon shaped, gauze-like extracellular matrices within which they then reside and proliferate without observable cell-cell adhesion and can do so in the complete absence of serum supplement in the culture media. This cell functioning is attributed to the direct access of oxygen to the cell attachment site.

The cochlear lesion in experimental bacterial meningitis of the rabbit

Sensorineural hearing loss was studied in a rabbit model of experimental bacterial meningitis using electrophysiological and ultrastructural techniques. Hearing impairment was monitored by auditory brain-stem evoked responses (ABERs) and concomitant structural lesions were identified by both transmission (TEM) and scanning (SEM) electron microscopy. Meningitis was induced by intra-cerebrospinal fluid injection of either Escherichia coli (strain 2073 and type K-12) or Haemophilus influenzae type b. Auditory loss of approximately equal to 10 dB occurred in all rabbits by about 10 hours post infection and progressed in severity until by 20 h following infection, hearing losses up to and > 60 dB were obtained. At levels of hearing loss < 20 dB ultrastructural damage to the organ of Corti was barely detectable. With greater levels of hearing loss, patchy structural damage to hair cells, synaptic nerve terminals, supporting cells and inner spiral sulcus cells and cells of the stria vascularis was clearly evident. Bacteria were found in scala tympani, the basilar membrane, the organ of Corti, scala media, the spiral ligament and at the margin of the stria vascularis. Evidence of bleeding was found in some cochleas; erythrocytes were found in scala tympani, scala media, amongst hair cells and beneath the tectorial membrane. The results show that hearing loss is associated with bacterial invasion and damage to the organ of Corti and that the cause of hearing loss is likely to result from multiple lesions within the cochlea. Lesions to sensory cells almost certainly will produce permanent hearing loss. Lesions to supporting cells, nerve terminals and to stria vascularis may well produce only temporary hearing loss.

Indole-3-carbinol. A novel approach to breast cancer prevention

The results show that all of the carcinogens, oncogenes, and tumor-associated viruses that we have studied profoundly affect the extent of 2- and 16 alpha-hydroxylation in a prorisk direction. All of the dietary and biological responses associated with increased cancer risk decrease 2-hydroxylation and increase 16 alpha-hydroxylation. Remarkably, although PAHs are reported to induce P450-1A1, we have found them to decrease 2-hydroxylation. Finally, using indole-3-carbinol to induce 2-hydroxylation results in the chemoprevention of mammary tumors in rodents and recurrences of laryngeal papillomas in humans. Also correlating with these studies in HPV is the decrease in the C-2/C-16 alpha metabolite ratio observed in women with CIN relative to control subjects. The greatest decrease was observed in women with the most severe form, CIN3 (Figure 23). These findings are under further investigation.

Chemoprevention of mammary preneoplasia. In vitro effects of a green tea polyphenol

The major findings of this study can be summarized as follows: (1) the c-myc oncogene-transfected and MTV-expressing mammary epithelial cells exhibit aberrant hyperproliferation in vitro preceding tumorigenesis in vivo; (2) upregulation of aberrant hyperproliferation (i.e., anchorage-independent growth) in initiated cells represents a cellular marker for preneoplastic transformation; (3) the tea polyphenol EGCG differentially downregulates aberrant hyperproliferation in myc oncogene- and MTV-initiated cells; (4) the present in vitro model provides an efficient assay for chemoprevention of mammary preneoplasia by naturally occurring compounds.

The role of estrogen in mammary carcinogenesis

The in vivo and in vitro studies conducted to examine whether E2 functions as an initiator or a promoter in mammary carcinogenesis can be summarized as follows: (1) Clinical and animal studies in vivo have shown a positive correlation of up-regulation of E2 C16 alpha-hydroxylation with either the presence of or the risk for breast cancer, suggesting that this metabolic alteration may represent an early-occurring event in the multistep process of tumorigenesis. (2) The mammary tissue, target for carcinogenesis, exhibits cancer risk-dependent alteration in E2 metabolism in the rodent and human mammary explant culture model, indicating that E2 metabolites may directly influence the mammary epithelium. (3) The 16 alpha-hydroxylated metabolite of E2, 16 alpha-OHE1, induces genotoxic DNA damage and aberrant hyperproliferation similar to that induced by chemical carcinogens in the rodent cell culture model. In preinitiated or fully transformed rodent or human cells, 16 alpha-OHE1 promotes the expression of transformed phenotype. (4) The initiator-mediated perturbation of E2 C16 alpha-hydroxylation in rodent and human mammary explant cultures is modulated by naturally occurring dietary constituents that are known to modulate rodent mammary tumorigenesis. (5) The observed effect of E2 on mammary tumorigenesis may be due in part to the generation of 16 alpha-OHE1, which functions as a weak initiator or a potent promoter of tumorigenic transformation in mammary epithelial cells. (6) The reaction of 16 alpha-OHE1 with the transcription factor ER is unique in that it can be irreversible and leads to aberrant gene expression.

NG-methyl-L-arginine protects the guinea pig cochlea from the cytotoxic effects of pneumolysin

Sensorineural hearing loss is a major sequela of the bacterial meningitis associated in particular with Streptococcus pneumoniae. Recent studies have shown pneumolysin, a toxin elaborated by S. pneumoniae, to be cytotoxic to the guinea pig cochlea. The mechanisms of this cytotoxicity are, however, not fully understood. In the present study this deleterious action of pneumolysin has been shown to be blocked by pretreating the cochlea with NG-methyl-L-arginine, a known inhibitor of nitric oxide synthesis. Furthermore, pretreatment of the cochlea with MK-801, an NMDA receptor antagonist, was also found to confer marked protection from the action of pneumolysin. This latter finding is consistent with previous reports that excess stimulation of NMDA receptors within the cochlea, an event known to lead to excess nitric oxide release, have similar effects on the cochlea as pneumolysin perfusion. It would therefore appear that nitric oxide may represent a significant link in the chain of events leading to the deafness of bacterial meningitis.

Long-term responses of women to indole-3-carbinol or a high fiber diet

We test the hypothesis that the estrogen metabolite ratio 2-OH-estrone:estriol can be raised via dietary indole-3-carbinol (I3C) and that this higher ratio can be sustained over a 3-month test period. We also explore the possible role of pure fiber on estradiol metabolism. Using a randomized clinical trial with three arms, each containing 20 subjects, arm 1 received 400 mg/day of I3C daily for 3 months, arm 2 received 20 g of alpha-cellulose daily for the same time period as a source of added fiber, and arm 3 received a placebo dose. Blood levels of a variety of biochemical parameters were measured. The urinary 2-OH-estrone:estriol estrogen metabolite ratio was measured monthly at the same time of the menstrual cycle. While no changes were observed in the control and alpha-cellulose-treated arms, a substantial mean increase in the ratio was observed in the I3C-treated arm at month 1; that increase was maintained over the 3-month time period. Three of the 20 subjects in this I3C-treated group differed from the others in that no significant change in the metabolite ratio was observed at any time point. The results suggest that I3C can serve to increase the 2-OH-estrone:estriol metabolite ratio in a sustained manner without detectable side effects and that some individuals may be resistant to such change.

Detection and management of bone marrow micrometastases in breast cancer

The presence and number of breast cancer micrometastases in the bone marrow at the time of diagnosis or initial treatment appear to predict early distant relapse. Immunologic techniques to detect such bone micrometastases, in combination with traditional prognostic variables, such as axillary lymph node status and tumor diameter, may allow for the identification of patients at high risk of systemic disease, who may benefit from adjuvant systemic chemotherapy. Immunofluorescent and immunochemical monoclonal antibody techniques have similar sensitivity in the detection of cancer cells in bone marrow. Future research is needed to develop more specific monoclonal antibodies and to determine the characteristics of the primary tumor that correlate with bone marrow micrometastasis, as well as the characteristics of micrometastases that correlate with recurrence.

Catechol estrogen production in rat microsomes after treatment with indole-3-carbinol, ascorbigen, or beta-naphthaflavone: a comparison of stable isotope dilution gas chromatography-mass spectrometry and radiometric methods

Compounds like indole-3-carbinol (I3C) have been shown to increase catechol estrogen formation and reduce mammary tumor incidence in mice. These compounds may exert a protective effect for breast cancer development by decreasing the overall estrogen pool available for the formation of 16 alpha-hydroxyestrone (16 alpha-OHE1), a metabolite that retains significant estrogenic activity, may be mutagenic and could represent a potential carcinogenic intermediate of estradiol degradation. I3C and ascorbigen originate from the breakdown of glucobrassicin. We have compared the inductive effects of I3C with ascorbigen and beta-naphthaflavone (Bnf) in microsomes from rats pretreated with these compounds using isotope dilution GC-MS and a radiometric method. Incubated microsomes from rats pretreated with I3C and ascorbigen yielded high levels of 2-hydroxyestradiol (2-OHE2) that were comparable to levels induced by Bnf and were significantly above control group levels (p < 0.005). Absolute values determined by the radiometric method were approximately 40% lower than 2-OHE2 concentrations determined by GC-MS, although the relative changes in each group were the same. These differences may be attributed to the radiolabel becoming trapped in microsomal intermediates in the sequence leading to tritium entering the aqueous compartment. Both ascorbigen- and Bnf-treated animals exhibited significant increases in 2-hydroxyestrone (2-OHE1) (p < 0.05). The ability of ascorbigen to induce estradiol C-2 hydroxylation has not been previously reported. Based on these data, we speculate that ascorbigen will act as an anticarcinogenic agent and will inhibit or reduce the incidence of mammary tumor formation.

Quantitative studies of invasion of rabbit ileal mucosa by Salmonella typhimurium strains which differ in virulence in a model of gastroenteritis

An asymmetric organ culture system in which ileal tissues, freshly removed from rabbits, can be maintained structurally and functionally for up to 4 h has been developed. The composition of the solutions used to maintain ileal tissue in vitro were as follows. The serosal surface was bathed in the World Health Organization (WHO) rehydration formulation: NaCl, 60 mM; NaHCO3, 30 mM; KCl, 20 mM; and glucose, 111 mM. The mucosal surface was bathed in the same solution with two important changes: all the sodium was replaced by choline, which is not absorbed, and tissue culture medium (consisting of commercial minimal essential medium to which was added fetal calf serum and glutamine to final concentrations of 10% [vol/vol] and 2.0 mM, respectively) was added to the choline-containing medium to a final concentration of 10% (vol/vol). The initial invasiveness (first 2 h) of seven strains of Salmonella typhimurium differing in virulence (defined in terms of clinical origin or the ability to induce fluid loss in monkeys or rabbit ileal loops) was assessed quantitatively in an in vitro invasion assay with the organ culture system. The virulent strains (TML, W118, and WAKE) were found to be about 25- to 100-fold more invasive than the avirulent strains (SL1027, M206, LT7, and Thax-1). Thus, a clear correlation between initial mucosal invasion and virulence of S. typhimurium in a model which is relevant to human gastroenteritis was established. This is the first time, to our knowledge, that quantitative studies of invasiveness have been carried out in vitro on freshly isolated functioning gut.

Current management of lobular carcinoma in situ of the breast

Lobular carcinoma in situ (lobular neoplasia) is usually a clinically inapparent incidental finding in breast biopsies, performed for an unrelated reason, in premenopausal women. The lesion, for which no uniformly acceptable histologic criteria exists, is associated with an increased long-term risk of developing invasive breast carcinoma in either breast. However, at the present time there is general consensus that the diagnosis of lobular carcinoma in situ does not necessarily predispose to an unavoidable malignancy in the lifetime of most patients and additional surgery may not be indicated. Long-term close surveillance, however, is required and such patients are candidates for cancer prevention trials.

Selective responsiveness of human breast cancer cells to indole-3-carbinol, a chemopreventive agent

BACKGROUND

Indole-3-carbinol (I3C), a compound found in cabbage, broccoli, and brussels sprouts, inhibits the growth of mammary tumors when fed to certain strains of mice. The chemopreventive and antitumor effects of I3C depend on the species and tissue type. The mechanism of action and specific human cell types that respond to I3C are not known.

PURPOSE

Our purpose was to study the mechanism of action of I3C in estrogen-responsive (MCF-7) and estrogen-nonresponsive (MDA-MB-231) human breast cancer cell lines.

METHODS

Estrogen responsiveness was determined by the ability of estradiol to stimulate the growth of breast cancer cells deprived of estrogen. The effect of I3C was measured on cell growth, estradiol metabolism, and level of cytochrome P-4501A1. Growth was measured by cell counts and soft-agar assay, estrogen metabolism was examined by a radiometric assay, and the level of cytochrome P-4501A1 was measured by Western blots with a polyclonal antibody.

RESULTS

I3C inhibits the growth of estrogen-responsive cell line MCF-7 but has little effect on estrogen-nonresponsive cell line MDA-MB-231. Specific C-2 hydroxylation of estrogen and induction of cytochrome P-4501A1 was enhanced by I3C in the MCF-7 but not in the MDA-MB-231 cells.

CONCLUSION

I3C has specific antigrowth effects in human breast cancer cells. The inhibitory effects of I3C may involve selective induction of estradiol metabolism and the related cytochrome P-450 system that may be limited to estrogen-sensitive cells.

Salvage surgery for recurrence after breast conservation

Breast conservation surgery and radiation therapy are chosen with increasing frequency in breast cancer management. In addition to the risk of developing a contralateral malignancy, these women are at risk for local recurrence or a new primary lesion in the conserved breast. Most of these ipsilateral recurrences can be treated successfully with salvage mastectomy. The prognosis with salvage mastectomy depends on several factors, including the method of diagnosis of the recurrent tumor, the size of the recurrence, the extent of breast involvement at recurrence, the time interval from initial surgery to recurrence, the involvement of axillary nodes at the initial diagnosis and at the time of recurrence, and the histopathology of the recurrent tumor.

Upregulation of estradiol C16 alpha-hydroxylation in human breast tissue: a potential biomarker of breast cancer risk

BACKGROUND

The biotransformation of the natural estrogen 17 beta-estradiol (E2) via the C16 alpha-hydroxylation pathway is elevated in patients with breast cancer, in subjects at increased risk for developing breast cancer, and in c-Ha-ras-initiated mouse mammary epithelial cells.

PURPOSE

To determine whether differences in the extent of E2 C16 alpha-hydroxylation are related to the risk of developing breast cancer, we examined the extent of biotransformation of E2 via the C16 alpha-hydroxylation pathway in the mammary terminal duct lobular units (TDLUs), epithelial organoids that are a presumptive target site of human breast carcinogenesis, and in nontarget component mammary fat tissue.

METHODS

Noninvolved mammary tissue was obtained from four patients undergoing reduction mammoplasty and from four undergoing mastectomy for breast cancer. A radiometric assay that measures 3H2O formation caused by stoichiometric 3H exchange from [C16 alpha-3H]E2 was utilized to compare the relative extent of C16 alpha-hydroxylation in explant cultures of TDLUs and mammary fat.

RESULTS

The extent of E2 C16 alpha-hydroxylation was 1.83-fold higher (95% confidence interval [CI] = 1.71-1.97) in the TDLUs from reduction mammoplasty (i.e., "low-risk") patients and 7.96-fold higher (95% CI = 6.38-10.55) in the TDLUs from mastectomy (i.e., "high-risk") patients than in the corresponding values observed in the mammary fat. In the TDLUs obtained from the patients undergoing mastectomy for cancer, the extent of this metabolism was 4.56-fold higher (95% CI = 3.97-5.33) than that observed in TDLUs obtained from reduction mammoplasty patients who did not have cancer.

CONCLUSION

The increase in the extent of C16 alpha-hydroxylation of E2 in the epithelial organoids of the human breast, TDLUs in particular, may be an important factor for breast cancer induction. This upregulation may represent an endocrine biomarker for the risk of developing breast cancer.

IMPLICATION

A larger prospective study is required to confirm the clinical significance of this endocrine biomarker.

Experimental down-regulation of intermediate biomarkers of carcinogenesis in mouse mammary epithelial cells

The polycyclic aromatic hydrocarbon 7,12-dimethylbenz(a)anthracene (DMBA) is a metabolism-dependent procarcinogen whose tumorigenicity is modified by dietary and endocrine manipulations in vivo. DMBA initiates molecular and cellular alterations in the mammary tissue, while dietary components and estrogens affect the post-initiational phase of tumorigenic transformation. The mechanism(s) responsible for modulation of tumorigenic transformation remain unclear. This study examines the effects of selected tumor suppressing agents and estradiol (E2) metabolites on in vitro DMBA carcinogenesis utilizing a newly established mouse mammary epithelial cell line C57/MG. Alteration in DNA repair synthesis, metabolism of E2 via the C2- and C16 alpha-hydroxylation pathways, and acquisition of anchorage-independent growth were utilized as molecular, endocrine, and cellular biomarkers to quantitate the cellular transformation by DMBA and its modulation by tumor suppressing agents and E2 metabolites. A single 24 hr exposure of 0.78 microM DMBA to C57/MG cells resulted in a 193.9% increase in DNA repair synthesis and a 73.1% decrease in C2/C16 alpha hydroxylation of E2. The DMBA treated C57/MG cells also exhibited increased anchorage-independence in vitro prior to tumorigenesis in vivo. A simultaneous treatment of cells with DMBA and with the highest noncytotoxic doses of the tumor suppressing agents 5 microM N-(4-hydroxyphenyl) retinamide (HPR), 50 microM indole-3-carbinol (I3C), or 1 microM tamoxifen (TAM) resulted in a 35.6% to 63.9% decrease in DNA repair synthesis, a 23.8% to 1347.6% increase in C2/C16 alpha hydroxylation of E2, and a 53.8% to 72.4% decrease in anchorage-independent growth. The E2 metabolites at the highest non-cytotoxic doses of 0.76 microM estrone (E1), 0.69 microM 2-hydroxyestrone (2-OHE1), and 0.66 microM 2-methoxyestrone (2-MeOHE1) suppressed DMBA-induced DNA repair synthesis by 56.0% to 68.8%. These tumor suppressing agents and E2 metabolites also effectively suppressed post-initiational, anchorage-independent growth by 24.9% to 72.4%. These results indicate that DMBA induces cellular transformation in part by causing DNA damage, altering C2/C16 alpha hydroxylation in favor of C16 alpha-hydroxylation, and inducing anchorage-independent growth prior to tumor development. Effective downregulation of these genotoxic, endocrine and proliferative end points by prototypic tumor suppressing agents and by E2 metabolites generated via the C2-hydroxylation pathway suggest that these agents may influence mammary tumorigenesis by inhibiting early occurring initiational and/or post initiational events.

Ependymal cells of the choroid plexus express tumour necrosis factor-alpha

Tumour necrosis factor-alpha (TNF alpha) is a major proinflammatory cytokine which appears in the cerebrospinal fluid very early after endotoxin challenge, and is likely to be produced locally. Following in vivo and in vitro challenge with endotoxin, we have demonstrated immunocytochemically and by in situ hybridization that pig and guinea-pig choroid plexus ependymal cells can produce TNF alpha. Immuno-electron microscopy shows that this protein is localized within ependymal cells to the cytoplasm and microvilli. We suggest that this TNF alpha may be important in the initiation of the inflammatory response in bacterial meningitis.

Alteration in proliferative and endocrine responsiveness of human mammary carcinoma cells by prototypic tumor-suppressing agents

The experiments performed in this study were designed to establish that (1) acquisition of anchorage-independent growth, a biological characteristic of tumorigenically transformed phenotype, can be modulated by prototypic tumor-suppressing agents, and (2) modulation of growth is influenced by the metabolic competence of the cells to biotransform estradiol, MCF-7 human breast carcinoma cells exhibited linear cell proliferative kinetics with a 41-hour population doubling time, and a 15% colony-forming efficiency in 0.33% agar. Indole-3-carbinol (13C), a naturally occurring tumor-suppressive agent; tamoxifen (TAM), an antiestrogenic agent; and 4-hydroxytamoxifen (4-OHTAM), a metabolite of TAM, demonstrated 73.7%, 72.5%, and 89.9% suppression in anchorage-independent growth of MCF-7 cells, respectively. At the metabolic level, 13C and 4-OHTAM induced 2.3-fold (P < 0.0001) and 1.3-fold increase (P = 0.001) relative to their own controls in the extent of 2-hydroxylation of estradiol. The results indicate that growth inhibition by 13C, TAM, and 4-OHTAM may in part be due to altered estradiol metabolism in MCF-7 cells. Thus, anchorage-independent growth and altered biotransformation of estradiol may constitute useful cellular and endocrine markers to evaluate the biological response of chemosuppressive agents.

Cytotoxic effects on hair cells of guinea pig cochlea produced by pneumolysin, the thiol activated toxin of Streptococcus pneumoniae

The cytolytic toxin, pneumolysin, from the gram positive bacterium, Streptococcus pneumoniae, when perfused through the scala tympani of the guinea pig cochlea reduced the amplitude of both the compound action potential and the cochlear microphonic potential. When the surface of the organ of Corti was examined by scanning electron microscopy, both inner and outer hair cells and supporting cells were found to be damaged. Inner hair cells and outer hair cells of row 3 were the most susceptible to damage by pneumolysin, followed by row 2 and then by row 1 of the outer hair cells. Damage to hair cells included disruption and splaying of stereocilia, loss of stereocilia and complete dissolution of hair bundles. Apical surfaces of hair cells and supporting cells were torn, pitted and cratered with shrinkage and tearing of cell boundaries. Within the dose range perfused (0.05-1 micrograms/microliters in a 10 microliters aliquot), the magnitude of the physiological and anatomical lesions was concentration dependent. The cytotoxic effects of pneumolysin reported here may be clinically significant factors in deafness caused by meningitis and otitis media in humans.