Emergent Premedication for Contrast Allergy Prior to Endovascular Treatment of Acute Ischemic Stroke.

BACKGROUND AND PURPOSE: Management of contrast media allergies may lead to treatment delays in patients with acute ischemic stroke undergoing endovascular therapy. The optimal premedication strategy remains unclear. The aim of this report was to analyze our experience with emergent administration of premedication regimens before endovascular therapy. MATERIALS AND METHODS: We retrospectively reviewed prospective data for all patients undergoing endovascular therapy from 2012 to 2019 at an academic comprehensive stroke center. Records of patients with documented contrast allergy were reviewed and analyzed. Data collected included stroke risk factors and characteristics, historical contrast reaction details, premedication regimens administered, and signs or symptoms of allergic reaction developing post-endovascular therapy. Hospital arrival time to endovascular therapy was compared with that in those who did not have a history of contrast allergy. RESULTS: We analyzed 1521 patients undergoing endovascular therapy; 60 (4%) had documented contrast allergies and constituted the study cohort. The median age was 73 years (interquartile range, 66-81 years), and 65% were women. The median time from premedication to contrast was 24 minutes (interquartile range, 0-36 minutes). Forty-three patients (72%) proceeded directly to endovascular therapy; in 17 patients, the first contrast exposure was CTA. Time from hospital arrival to endovascular therapy was not slower for patients with documented allergies (96 versus 134 minutes, P = .32). No patients experienced a contrast media reaction. CONCLUSIONS: In a single-institution cohort study of 60 consecutive patients with documented contrast allergies undergoing endovascular therapy with emergent premedication en route to (or in) the neuroangiography suite, no patients experienced allergic symptoms. This pragmatic approach may be safe for patients who have documented contrast media allergies.

Dynamic transcription factor activity and networks during ErbB2 breast oncogenesis and targeted therapy.

Tissue development and disease progression are multi-stage processes controlled by an evolving set of key regulatory factors, and identifying these factors necessitates a dynamic analysis spanning relevant time scales. Current omics approaches depend on incomplete biological databases to identify critical cellular processes. Herein, we present TRACER (TRanscriptional Activity CEll aRrays), which was employed to quantify the dynamic activity of numerous transcription factor (TFs) simultaneously in 3D and networks for TRACER (NTRACER), a computational algorithm that allows for cellular rewiring to establish dynamic regulatory networks based on activity of TF reporter constructs. We identified major hubs at various stages of culture associated with normal and abnormal tissue growth (i.e., ELK-1 and E2F1, respectively) and the mechanism of action for a targeted therapeutic, lapatinib, through GATA-1, which were confirmed in human ErbB2 positive breast cancer patients and human ErbB2 positive breast cancer cell lines that were either sensitive or resistant to lapatinib.

Crosstalk between PKCα and Notch-4 in endocrine-resistant breast cancer cells.

The Notch pathway is functionally important in breast cancer. Notch-1 has been reported to maintain an estrogen-independent phenotype in estrogen receptor α (ERα)+ breast cancer cells. Notch-4 expression correlates with Ki67. Notch-4 also plays a key role in breast cancer stem-like cells. Estrogen-independent breast cancer cell lines have higher Notch activity than estrogen-dependent lines. Protein kinase Cα (PKCα) overexpression is common in endocrine-resistant breast cancers and promotes tamoxifen (TAM)-resistant growth in breast cancer cell lines. We tested whether PKCα overexpression affects Notch activity and whether Notch signaling contributes to endocrine resistance in PKCα-overexpressing breast cancer cells.Analysis of published microarray data from ERα+ breast carcinomas shows that PKCα expression correlates strongly with Notch-4. Real-time reverse transcription PCR and immunohistochemistry on archival specimens confirmed this finding. In a PKCα-overexpressing, TAM-resistant T47D model, PKCα selectively increases Notch-4, but not Notch-1, expression in vitro and in vivo. This effect is mediated by activator protein-1 (AP-1) occupancy of the Notch-4 promoter. Notch-4 knockdown inhibits estrogen-independent growth of PKCα-overexpressing T47D cells, whereas Notch-4IC expression stimulates it. Gene expression profiling shows that multiple genes and pathways associated with endocrine resistance are induced in Notch-4IC- and PKCα-expressing T47D cells. In PKCα-overexpressing T47D xenografts, an orally active γ-secretase inhibitor at clinically relevant doses significantly decreased estrogen-independent tumor growth, alone and in combination with TAM. In conclusion, PKCα overexpression induces Notch-4 through AP-1. Notch-4 promotes estrogen-independent, TAM-resistant growth and activates multiple pathways connected with endocrine resistance and chemoresistance. Notch inhibitors should be clinically evaluated in PKCα- and Notch-4-overexpressing, endocrine-resistant breast cancers.

Elevated protein kinase C alpha expression may be predictive of tamoxifen treatment failure.

We previously reported that stable transfection of protein kinase C alpha (PKCalpha) into T47D human breast cancer cells results in tamoxifen (TAM)-resistant tumour growth. Relevance of PKCalpha expression in clinical specimens was determined by comparing PKCalpha expression in tumours from patients exhibiting disease recurrence with patients remaining disease-free following TAM treatment. Our results suggest that PKCalpha expression may predict TAM treatment failure.

Novel antitumor effect of estradiol in athymic mice injected with a T47D breast cancer cell line overexpressing protein kinase Calpha.

PURPOSE: Resistance to tamoxifen (TAM) represents a significant challenge to the management of breast cancer. We previously reported that the estrogen receptor (ER)-negative hormone-independent T47D:C42 cell line has both elevated protein kinase Calpha (PKCalpha) protein expression and basal activator protein-1 activity compared with the parental ER+ (hormone-dependent) T47D:A18 cell line. Stable transfection of PKCalpha to the T47D:A18 breast cancer cell line results in increased basal activator protein-1 activity, reduced ER function, increased proliferation rate, and hormone-independent growth (Tonetti et al., Br. J. Cancer, 83: 782-791, 2000). In this report, we further characterize the role of PKCalpha overexpression in vivo to elucidate a possible molecular mechanism of tamoxifen resistance. EXPERIMENTAL DESIGN: To determine whether the T47D:A18/PKCalpha cell line would produce hormone-independent tumors in athymic mice, we injected T47D:A18, T47D:A18/neo, or the T47D:A18/PKCalpha20 cell clones bilaterally into the mammary fat pads of athymic mice. Tumor growth was evaluated following treatment with estradiol (E2), TAM, and the pure antiestrogen, ICI 182,780. RESULTS: Mice receiving either T47D:A18 or T47D:A18/neo cells produced tumors that grew in response to E2 treatment, whereas the untreated control and TAM-treated groups showed no tumor growth. Interestingly, mice receiving the T47D:A18/PKCalpha20 clone produced tumors in both the control and TAM groups, whereas tumor growth was inhibited in mice treated with E2. PKCalpha was also overexpressed in an MCF-7 tumor model that also exhibited TAM-stimulated and E2-induced regression. CONCLUSIONS: These results suggest that overexpression of PKCalpha in breast tumors results in hormone-independent tumor growth that cannot be inhibited by TAM treatment. Furthermore, the finding that E2 has an antitumor effect on breast tumors overexpressing PKCalpha is a novel observation that may have important therapeutic implications.

Protein kinase C alpha expression is inversely related to ER status in endometrial carcinoma: possible role in AP-1-mediated proliferation of ER-negative endometrial cancer.

OBJECTIVE: Tamoxifen is the most widely used antiestrogen to treat all stages of estrogen-receptor (ER)-positive breast cancers. However, tamoxifen acts as a partial estrogen in the uterus and is known to increase the risk of endometrial cancer by two- to threefold. Recent evidence indicates that there is a connection between tamoxifen resistance and activation of the activator protein-1 (AP-1) pathway. We have previously reported a possible role for overexpression of protein kinase C alpha (PKCalpha), an upstream activator of the AP-1 pathway, in hormone-independent breast cancer and antiestrogen-stimulated endometrial tumors. We hypothesize that alterations of the PKC isozyme profile of endometrial carcinomas are similar to that of hormone-independent breast cancer and determine whether specific PKC isozyme alterations correlated with known clinicopathological features of endometrial cancer. METHODS: The PKC isozyme profile of endometrial carcinomas from 42 patients who were not previously exposed to antiestrogens was examined by Western blot. The relationship between PKC isozyme expression and key prognostic factors for endometrial carcinoma including hormone receptor status, tumor grade, stage, size, and depth of myometrial invasion was examined using the Spearman's rho correlation coefficient. RESULTS: As previously found in breast cancers, PKCalpha and estrogen receptor alpha (ERalpha) expression are inversely related (r(s) = -0.35, P = 0.046). We report significant inverse correlations among ER/progesterone receptor (PR) expression and tumor grade (r(s) = -0.49, P = 0.001 and r(s) = -0.44, P = 0.004, respectively), ER, and depth of myometrial invasion (r(s) = -0.40, P = 0.009). There were no other significant correlations between PKC isozyme expression and other key prognostic factors examined. CONCLUSION: This study indicates that, similar to what was previously observed in breast cancer, PKCalpha and ER expression is inversely related in endometrial cancer. PKCalpha expression may be a useful prognostic indicator in endometrial cancers. A model is offered which describes the putative role of PKCalpha overexpression in activation of the AP-1 pathway and increased proliferation of ER negative endometrial cancers.

Stable transfection of protein kinase C alpha cDNA in hormone-dependent breast cancer cell lines.

An inverse relationship between protein kinase C (PKC) activity and oestrogen receptor (ER) expression in human breast cell lines and tumours has been firmly established over the past 10 years. To determine whether specific alterations in PKC expression accompany hormone-independence, we examined the expression of PKC isozymes in the hormone-independent human breast cancer cell clones MCF-7 5C and T47D:C42 compared with their hormone-dependent counterparts, MCF-7 A4, MCF-7 WS8 and T47D:A18 respectively. Both hormone-independent cell clones exhibit elevated PKC alpha expression and increased basal AP-1 activity compared with the hormone-dependent cell clones. To determine whether PKC alpha overexpression is sufficient to mediate the hormone-independent phenotype, we stably transfected an expression plasmid containing PKC alpha cDNA to the T47D:A18 and MCF-7 A4 cell lines. This is the first report of PKC alpha transfection in T47D cells. In contrast to MCF-7 cells, T47D has the propensity to lose the ER and more readily forms tamoxifen-stimulated tumours in athymic mice. We find that in T47D:A18/PKC alpha clones, there is concomitant up-regulation of PKC beta I and delta, whereas in the MCF-7 A4/PKC alpha transfectants PKC epsilon is up-regulated. In T47D:A18, but not in MCF-7 A4, PKC alpha stable transfection is accompanied by down-regulation of ER function whilst basal AP-1 activity is elevated. Our results suggest PKC alpha overexpression may play a role in growth signalling during the shift from hormone dependent to hormone-independent breast cancers.

The interaction of raloxifene and the active metabolite of the antiestrogen EM-800 (SC 5705) with the human estrogen receptor.

A naturally occurring mutation at amino acid 351 (D351Y) in the human estrogen receptor (ER) can change the pharmacology of antiestrogens. Raloxifene is converted from an antiestrogen to an estrogen, whereas the biological properties of the steroidal pure antiestrogen ICI 182,780 are not affected by the D351Y ER (Levenson, A. S., and Jordan, V. C. Cancer Res., 58: 1872-1875, 1998). We propose an assay system that can be used to classify antiestrogens by determining their ability to up-regulate transforming growth factor alpha (TGF-alpha) mRNA in MDA-MB-231 cells stably transfected with either wild-type or D351Y ER. The novel compound EM-800 and its active metabolite, EM-652, have been reported to be p.o. active nonsteroidal pure antiestrogens. Using the D351Y cell line, EM-652 is able to up-regulate TGF-alpha mRNA in a dose-dependent manner and to a similar extent as estradiol, whereas in the wild-type cell line, it acts as an antiestrogen. In addition, the pure antiestrogen ICI 182,780 is capable of inhibiting EM-652-induced TGF-alpha mRNA expression at the D351Y ER. In MCF-7 cells expressing wild-type ER, it has previously been shown that ICI 182,780 decreases ER only at the protein level. EM-652 treatment does not decrease ER protein levels to a similar extent as ICI 182,780 treatment, and, in addition, EM-652 has no effect on ER mRNA levels. In proliferation assays, EM-652 is as effective as raloxifene in inhibiting cell growth. From these studies, we conclude that the reason the pharmacology of EM-652 is similar to that of raloxifene is because they both fit the ER in the same manner, and their biology depends on an interaction of the antiestrogenic side chain with amino acid 351.

The estrogen receptor: a logical target for the prevention of breast cancer with antiestrogens.

A strategy for the prevention of breast cancer has been refined over the last century beginning with the first observation that oophorectomy caused disease regression in some patients, to the identification of the estrogen receptor some 60 years later, and finally to the synthesis of the first nonsteroidal antiestrogen. Tamoxifen was the first clinically useful antiestrogen and has been used for the treatment of breast cancer for the last twenty-one years in the United States. It is therefore a logical progression that antiestrogens are now recognized as useful agents for the prevention of breast cancer. We will discuss the estrogen receptor as a target for the treatment and now the prevention of breast cancer. Data from the National Surgical and Bowel Project (NSABP)4 tamoxifen prevention trial will be discussed with the preliminary results of two other European studies. The status of breast cancer prevention to date involves the comparison of the current standard of prevention, tamoxifen, with the osteoporosis prevention drug, raloxifene in an ongoing trial called Study of Tamoxifen and Raloxifene (STAR).

Antiestrogen stimulated human endometrial cancer growth: laboratory and clinical considerations.

The new antiestrogen toremifene (TOR) is currently on the market for the treatment of advanced breast cancer in postmenopausal women. TOR is known to exhibit a similar efficacy profile as tamoxifen (TAM) in the treatment of advanced breast cancer and there are studies to suggest that the beneficial side effects of TAM on bone and blood lipids are also achieved with TOR. However, the data concerning the action of TOR on the endometrium is sorely lacking. In light of the estrogenic effect of TAM on the uterus and the 2-3-fold increased incidence in endometrial carcinoma detected in patients receiving TAM therapy, it is imperative to investigate the effect of TOR on endometrial carcinoma. We compared the actions of TAM and TOR on the EnCa101 human endometrial tumor model and find that both antiestrogens have similar growth stimulatory effects. To investigate a potential mechanism of antiestrogen-stimulated endometrial tumor growth, we have examined known activators of the AP-1 signal transduction pathway, the protein kinase C (PKC) family of isozymes, in the EnCa101 human endometrial tumor model. We find that increased PKC isozyme expression correlates with hormone-independent breast cancer as well as antiestrogen-stimulated endometrial cancer.

The oestrogen-like effect of 4-hydroxytamoxifen on induction of transforming growth factor alpha mRNA in MDA-MB-231 breast cancer cells stably expressing the oestrogen receptor.

Oestrogens and antioestrogens modulate the synthesis of transforming growth factor alpha (TGF-alpha) in breast cancer cells. The purpose of the present report was to examine regulation of TGF-alpha gene expression by oestradiol (E2) and antioestrogens in MDA-MB-231 breast cancer cells transfected with either the wild-type or mutant oestrogen receptor (ER). We recently reported the concentration-dependent E2 stimulation of TGF-alpha mRNA in MDA-MB-231 ER transfectants (Levenson et al, 1997). We now report that 4-hydroxytamoxifen (4-OHT) shows oestrogen-like effects on the induction of TGF-alpha gene expression in our transfectants. Accumulation of TGF-alpha mRNA in response to both E2 and 4-OHT but not in response to the pure antioestrogen ICI 182,780 suggests that E2-ER and 4-OHT-ER complexes can bind to an oestrogen response element (ERE), located in the promoter region of the TGF-alpha gene and can activate transcription of the gene. Surprisingly, no activation of luciferase expression was observed after transient transfection of the TGF-alpha ERE/luciferase reporter constructs. Possible activation of an alternative ER-mediated pathway responsible for the regulation of TGF-alpha gene expression in the ER transfectants is discussed.

The role of estrogen receptor mutations in tamoxifen-stimulated breast cancer.

During the past 20 years, the hormonal therapy of choice for the treatment of breast cancer has been the antiestrogen, tamoxifen. The use of tamoxifen has been proved to produce a favorable response and survival advantage in patients whose tumors are classified as estrogen receptor-positive (ER+)/progesterone receptor-positive (PR+). Additionally, tamoxifen is the only drug known to reduce the incidence of contralateral disease. This drug produces relatively few harmful side effects, while exhibiting several beneficial effects such as maintaining bone density and reducing the incidence of myocardial infarction in the postmenopausal woman. However, tumors eventually acquire a tamoxifen-resistant or tamoxifen-stimulated phenotype, resulting in disease recurrence. Several mechanisms have been proposed to account for tamoxifen-resistant breast cancer, in the hope of developing a more effective first-line or perhaps second-line treatment strategy. One popular theory is the occurrence of a mutation in the estrogen receptor, the drug target. A plethora of studies have reported the detection of estrogen receptor mRNA splice variants, and it has been suggested that the accumulation of these variant mRNAs are responsible for the development of tamoxifen-resistant breast cancer. In this review, several questions will be posed to address the suitability of both laboratory and clinical evidence to support this hypothesis. Although there is adequate data generated in the laboratory, there is, as yet, no compelling evidence to suggest that mutation of the estrogen receptor is the molecular mechanism producing tamoxifen-stimulated growth in human breast and endometrial cancer.

Targeted anti-estrogens to treat and prevent diseases in women.

The estrogen receptor has been successfully targeted with the anti-estrogen tamoxifen to treat all stages of breast cancer. Because tamoxifen is a partial agonist, it exhibits target-site specificity: it acts as an anti-estrogen in the breast to inhibit tumor growth, while exhibiting estrogenic effects on bones and lipid metabolism. Therefore, tamoxifen has the added benefit of maintaining bone density and reducing the risk of myocardial infarction in postmenopausal women. However, undesirable side effects of tamoxifen preclude its use as a hormone replacement therapy for otherwise healthy women. New anti-estrogens are currently being developed that may prevent osteoporosis, breast and endometrial cancer, and reduce the risk of myocardial infarction.

Possible mechanisms in the emergence of tamoxifen-resistant breast cancer.

Tamoxifen (TAM), a non-steroidal antiestrogen, is the endocrine treatment of choice for all stages of breast cancer. However, despite a favorable initial response to therapy, most tumors will eventually exhibit TAM resistance resulting in disease recurrence. Several mechanisms of TAM resistance have been proposed, yet a single distinct mechanism has not been identified. We will systematically consider the following steps of the estrogen receptor (ER)-mediated signal transduction pathway to identify possible sites of alteration leading to tamoxifen-resistance: (1) ligand metabolism and availability, (2) loss or mutation of the ER, (3) defects in ER post-translational modification, and (4) alteration of the estrogen response element (ERE). In particular, the ERE will be discussed as a position in the signal transduction pathway with considerable potential, if altered, to confer TAM resistance.

Protein kinase C-beta is required for macrophage differentiation of human HL-60 leukemia cells.

The requirement for protein kinase C (PKC)-beta in phorbol 12-myristate 13-acetate (PMA)-induced macrophage differentiation of human HL-60 promyelocytic leukemia cells was studied by using the variant HL-525, which is deficient in PKC-beta and is resistant to PMA-induced differentiation. Transfecting these resistant HL-525 cells with expression vectors containing either PKC-beta I or PKC-beta II cDNA resulted in clones that displayed PKC-beta transcript levels similar to or higher than those of the parental HL-60 cells or cells from a PMA-susceptible HL-60 clone, HL-205. These productive transfectants also exhibited PMA-induced cell attachment and spreading, inhibition of cell replication, reactivity to the OKM1 monoclonal antibody, and the ability to phagocytize opsonized beads, which are all characteristic macrophage markers. No PMA-induced differentiation markers were observed in any of the PKC-beta I or PKC-beta II transfectants that did not exhibit an increased PKC-beta RNA level or in cells transfected with control plasmids. These results indicate that restoration of the PKC-beta isozyme deficiency by productive gene transfection causes HL-525 cells to revert to a phenotype like that of the parental HL-60 cells, which is characterized by susceptibility to PMA-induced macrophage differentiation. Therefore, we can conclude that PKC-beta is one of the essential elements in the PMA-induced signal transduction pathway which leads to macrophage differentiation in HL-60 cells and perhaps in other related cell types.