UCN-01, a protein kinase C inhibitor, inhibits endothelial cell proliferation and angiogenic hypoxic response

CLM94, a novel cyclic amide with anti-VEGFR-2 and antiangiogenic properties, is active against primary anaplastic thyroid cancer in vitro and in vivo

CONTEXT AND OBJECTIVE

We have studied the antitumor activity of a novel cyclic amide, CLM94, with anti-vascular endothelial growth factor (VEGF) receptor-2 and antiangiogenic activity in primary anaplastic thyroid cancer (ATC) cells in vitro and in vivo.

DESIGN AND MAIN OUTCOME MEASURES

CLM94 was tested: 1) in two human cell lines (HMVEC-d, dermal microvascular endothelial cells; and 8305C, undifferentiated thyroid cancer) at 0.001-100 μm; 2) in ATC cells at the concentrations of 10, 30, and 50 μm; and 3) in an ATC cell line (AF) in CD nu/nu mice.

RESULTS

CLM94 significantly inhibited VEGF receptor-2 and epidermal growth factor receptor phosphorylation in HMVEC-d and proliferation in HMVEC-d and 8305C cells. A significant reduction of proliferation with CLM94 in ATC cells (P < 0.01, ANOVA) and a slight but significant reduction of proliferation with CLM94 30 and 50 μm in normal thyroid follicular cells (P < 0.01, ANOVA) were shown. CLM94 increased the percentage of apoptotic ATC cells dose-dependently (P < 0.001, ANOVA) and inhibited migration (P < 0.01) and invasion (P < 0.001). AF cell line was injected sc in CD nu/nu mice, and tumor masses became detectable 25 d afterward. CLM94 (40 mg/kg · d) significantly inhibited tumor growth (starting 10 d after the beginning of treatment). CLM94 significantly decreased the VEGF-A gene expression in the AF cell line and the VEGF-A protein and microvessel density in AF tumor tissues.

CONCLUSIONS

The antitumor and antiangiogenic activity of a new "cyclic amide" compound, CLM94, is very promising in ATC, opening the way to a future clinical evaluation.

Modulation of hypoxia-inducible factors (HIF) from an integrative pharmacological perspective

Oxygen homeostasis determines the activity and expression of a multitude of cellular proteins and the interplay of pathways that affect crucial cellular processes for development, physiology, and pathophysiology. Hypoxia-inducible factors (HIFs) are transcription factors that respond to changes in available oxygen in the cellular environment and drives cellular adaptation to such conditions. Selective gene expression under hypoxic conditions is the result of an exquisite regulation of HIF, from the pre-transcriptional stage of the HIF gene to the final transcriptional activity of HIF protein. We provide a dissected analysis of HIF modulation with special focus on hypoxic conditions and HIF pharmacological interventions that can guide the application of any future HIF-mediated therapy.

Angiogenic activity of human chorionic gonadotropin through LH receptor activation on endothelial and epithelial cells of the endometrium

Successful embryo development requires an extensive endometrial angiogenesis in proximity of implantation site. The glycoprotein hCG is produced even before implantation by trophoblast in normal pregnancy. In this manuscript, we demonstrate an angiogenic effect of hCG in several in vivo (chick chorioallantoïc membrane, matrigel plug assay, aortic ring assay) and in vitro experimental models. In contrast, human placental lactogen (hPL) did not display angiogenic properties. LH/hCG receptor was detected in endothelial cells by reverse-transcriptase polymerase chain reaction (RT-PCR) and by Western blotting. In mice aortic ring assay, angiostimulation by hCG was abrogated by deletion of LH/hCG receptor (LuRKO mice). Use of recombinant hCG and anti-hCG antibody (Ab) further confirmed the specificity of this angiogenic activity. By using dibutyryl cAMP, adenylate cyclase, or protein kinase A inhibitors, we demonstrate that hCG-mediated angiogenesis involves adenylyl-cyclase-protein kinase A activation. Addition of hCG to endometrial epithelial epithelial cells, but not to cultured endothelial cells, stimulated vascular endothelial growth factor (VEGF). VEGF and hCG also displayed additive activities. Altogether, these data demonstrate that peritrophoblastic angiostimulation may result from a paracrine dialogue between trophoblast, epithelial, and endothelial cells through hCG and VEGF.

Natural product-based inhibitors of hypoxia-inducible factor-1 (HIF-1)

The transcription factor hypoxia-inducible factor-1 (HIF-1) regulates the expression of more than 70 genes involved in cellular adaptation and survival under hypoxic stress. Activation of HIF-1 is associated with numerous physiological and pathological processes that include tumorigenesis, vascular remodeling, inflammation, and hypoxia/ischemia-related tissue damage. Clinical studies suggested that HIF-1 activation correlates directly with advanced disease stages and treatment resistance among cancer patients. Preclinical studies support the inhibition of HIF-1 as a major molecular target for antitumor drug discovery. Considerable effort is underway, in government laboratories, industry and academia, to identify therapeutically useful small molecule HIF-1 inhibitors. Natural products (low molecular weight organic compounds produced by plants, microbes, and animals) continue to play a major role in modern antitumor drug discovery. Most of the compounds discovered to inhibit HIF-1 are natural products or synthetic compounds with structures that are based on natural product leads. Natural products have also served a vital role as molecular probes to elucidate the pathways that regulate HIF-1 activity. Natural products and natural product-derived compounds that inhibit HIF-1 are summarized in light of their biological source, chemical class, and effect on HIF-1 and HIF-mediated gene regulation. When known, the mechanism(s) of action of HIF-1 inhibitors are described. Many of the substances found to inhibit HIF-1 are non-druggable compounds that are too cytotoxic to serve as drug leads. The application of high-throughput screening methods, complementary molecular-targeted assays, and structurally diverse chemical libraries hold promise for the discovery of therapeutically useful HIF-1 inhibitors.

Vascular patterns in glioblastoma influence clinical outcome and associate with variable expression of angiogenic proteins: evidence for distinct angiogenic subtypes

No data exist on angiogenic patterns and their prognostic impact in human glioblastoma. Such data are relevant for translation of antiangiogenic therapies into clinical applications. Using immunohistochemistry for CD34, we assessed vascular patterns in 114 primary glioblastomas. Vascular patterns comprised unevenly distributed glomeruloid/garland-like/clustered bizarre vascular formations and evenly distributed delicate capillary-like microvessels ("classic" vascular pattern). The combination of low content of bizarre vascular formations and prominent classic vascular pattern (n=29) was an independent factor for longer survival (p=0.006, Cox regression), as well as postoperative high Karnofsky performance status (p=0.005). In patients with a prominent classic vascular pattern, there was no difference of MIB1 labeling index whereas microvessel density and apoptotic index (TUNEL) were significantly higher as compared to all other patients (p<0.05). In addition, diffuse expression of hypoxia-inducible factor (HIF)-1alpha and strong expression of vascular endothelial growth factor were more common (p<0.05, Chi-square test). FISH revealed loss of chromosomes 1p and 19q only in 1/7 long-time survivors with classic pattern. We conclude that vascular patterns in primary glioblastoma influence clinical outcome and associate with variable expression of angiogenic proteins. Our findings denote for the first time distinct angiogenic subtypes of human glioblastoma which may prove relevant for anti-angiogenic therapy approaches.

Pyrimidine and purine analogues, effects on cell cycle regulation and the role of cell cycle inhibitors to enhance their cytotoxicity

In anti-cancer treatment, deoxynucleoside analogues are widely used in combination chemotherapy. Improvement can be achieved by rational design of novel combinations with cell cycle inhibitors. These compounds inhibit protein kinases, preventing the cell cycle from continuing when affected by deoxynucleoside analogs. The efficacy is dependent on the site of cell cycle inhibition, whether multiple cyclin-dependent kinases are inhibited and whether the inhibitors should be given before or after the deoxynucleoside analogs. The action of cell cycle inhibition in vivo may be limited by unfavorable pharmacokinetics. Preclinical and clinical studies will be discussed, aiming to design improved future strategies.

Novel concepts of human chorionic gonadotropin: reproductive system interactions and potential in the management of infertility

OBJECTIVE

To extensively review the scientific literature on the potential sites of hCG action and the role of this hormone on reproductive processes not necessarily related to the classic hCG functions of supporting early pregnancy.

DESIGN

Review of the international scientific literature and the authors' personal research experience in this area.

RESULT(S)

The LH/hCG receptor has an almost ubiquitous distribution in reproductive organs, thus suggesting that the actions of hCG might be more extensive than previously thought. Independently of FSH, low-dose hCG can support development and maturation of larger ovarian follicles that have acquired granulosa cells LH/hCG receptors, potentially providing effective and safer ovulation induction regimens. Human chorionic gonadotropin seems to be capable of improving uterine receptivity by enhancing endometrial quality and stromal fibroblast function. Furthermore, through its actions on insulin-like growth factor binding protein-1 and vascular endothelial growth factor, hCG might stimulate endometrial angiogenesis and growth and extend the implantation window, thus making pregnancy more likely.

CONCLUSION(S)

Mounting evidence indicates that hCG could be mediating relevant actions enhancing fertility and the efficacy of therapeutic procedures used in the management of infertility. Greater understanding of the physiologic roles that hCG plays in human reproduction might suggest novel clinical applications for this traditional hormone of pregnancy.

Effect of 7-hydroxystaurosporine on glioblastoma cell invasion and migration

AIM

To investigate the effect of 7-hydroxystaurosporine (UCN-01), a selective protein kinase C (PKC) inhibitor, on cell growth, migration, and invasion in invasive human glioblastoma U-87MG cells.

METHODS

PKC activity was determined based on the PKC-catalyzed transfer of the (32)P-phosphate group from [g-(32)P]ATP into a PKC-specific peptide substrate. Cell viability was measured by MTT assay. Cell invasion and migration were evaluated by a Boyden chamber assay and scratch wound assay, respectively. Protein expression was analyzed using Western blot assay. The formation of 3-dimensional cellular aggregates was examined by a cell-cell aggregation assay.

RESULTS

UCN-01 treatment resulted in concentration- and time-dependent inhibition of U-87MG cell growth at higher doses (>100 nmol/L), and reduced cell invasion and migration capability at less cytotoxic doses (<100 nmol/L). UCN-01 significantly repressed PKC activity. Consistent with this result, UCN-01 blocked cell invasion stimulated by phorbel 12-myristate-13-acetate (PMA) and ethanol (EtOH), 2 PKC activators. Enforced expression of the tumor suppressor genes BRCA1 and PTEN increased the anti-invasion potential of UCN-01. Exposure to UCN-01 caused a dose-dependent increase in cell adhesion molecule E-cadherin. The effect of UCN-01 on the formation of cell-cell aggregation was significantly reduced by the addition of an anti-E-cadherin antibody.

CONCLUSION

UCN-01 inhibits the invasion and migration of human glioma cells. Accordingly, UCN-01 can have potential clinical applications for the treatment of human glioma metastasis.

The broad-range cyclin-dependent kinase inhibitor UCN-01 induces apoptosis in colon carcinoma cells through transcriptional suppression of the Bcl-x(L) protein

The broad-range cyclin-dependent kinase inhibitor 7-hydroxystaurosporine (UCN-01) is known to induce both a G1 cell cycle arrest and apoptosis. The mechanism of UCN-01-induced apoptosis is largely unknown. We analysed the mechanism of cytotoxicity of UCN-01 in four established colon carcinoma cell lines. The cell lines SW48 and LS513 responded to UCN-01 treatment by undergoing apoptosis in a concentration-dependent manner while the cell lines HT-29 and WiDr were completely resistant. Apoptosis in LS513 and SW48 cell lines was concomitant with the suppression of Bcl-x(L) on mRNA and protein level. In contrast, in the apoptosis-resistant cell lines, Bcl-x(L) expression was not affected by UCN-01. Stable overexpression of the Bcl-x(L) protein abrogated UCN-01-triggered apoptosis, but only partially restored growth, indicating that both cell cycle arrest and apoptosis exert the anticancer effect in a coordinated manner. The inhibition of Akt phosphorylation did not correlate with the apoptotic phenotype. UCN-01 inhibited the activating STAT3 phosphorylations on Ser727 and, notably, on Tyr705, but STAT3 did not contribute to Bcl-x(L) expression in colon carcinoma cells. Moreover, we show for the first time that UCN-01 induces apoptosis by suppression of Bcl-x(L) expression. The inhibition of this pathway is a new aspect of cytotoxic and modulatory potential of UCN-01.

Targeting multiple signaling pathways as a strategy for managing prostate cancer: multifocal signal modulation therapy

The aberrant behavior of cancer reflects upregulation of certain oncogenic signaling pathways that promote proliferation, inhibit apoptosis, and enable the cancer to spread and evoke angiogenesis. Theoretically, it should be feasible to decrease the activity of these pathways-or increase the activity of pathways that oppose them-with noncytotoxic agents. Since multiple pathways are dysfunctional in most cancers, and cancers accumulate new oncogenic mutations as they progress, the greatest and most durable therapeutic benefit will likely be achieved with combination regimens that address several targets. Thus, a multifocal signal modulation therapy (MSMT) of cancer is proposed. This concept has already been documented by researchers who have shown that certain combinations of signal modulators-of limited utility when administered individually-can achieve dramatic suppression of tumor growth in rodent xenograft models. The present essay attempts to guide development of MSMTs for prostate cancer. Androgen ablation is a signal-modulating measure already in standard use in the management of delocalized prostate cancer. The additional molecular targets considered here include the type 1 insulin-like growth factor receptor, the epidermal growth factor receptor, mammalian target of rapamycin, NF-kappaB, hypoxia-inducible factor-1alpha, hsp90, cyclooxygenase-2, protein kinase A type I, vascular endothelial growth factor, 5-lipoxygenase, 12-lipoxygenase, angiotensin II receptor type 1, bradykinin receptor type 1, c-Src, interleukin-6, ras, MDM2, bcl-2/bclxL, vitamin D receptor, estrogen receptor-beta, and PPAR-. Various nutrients and phytochemicals suspected to have potential utility in prostate cancer prevention and therapy, but whose key molecular targets are still unknown, might reasonably be incorporated into MSMTs for prostate cancer; these include lycopene, selenium, green tea polyphenols, genistein, and silibinin. MSMTs can be developed systematically by testing various combinations of signal-modulating agents, in concentrations that can feasibly be achieved and maintained clinically, on human prostate cancer cell lines; combinations that appear promising can then be tested in xenograft models and, ultimately, in the clinic. Some signal modulators can increase response to cytotoxic drugs by upregulating effectors of apoptosis. When MSMTs fail to raise the spontaneous apoptosis rate sufficiently to achieve tumor stasis or regression, incorporation of appropriate cytotoxic agents into the regimen may improve the clinical outcome.

Hypoxia inducible factor-1α as a cancer drug target

The hypoxia inducible factor 1 (HIF-1) is a heterodimeric transcription factor that is an important regulator of the growing tumor's response to hypoxia. HIF-1 activity in tumors depends on the availability of the HIF-1α subunit, the levels of which increase under hypoxic conditions and through the activation of oncogenes and/or inactivation of tumor suppressor genes. HIF-1 activates genes that allow the cancer cell to survive and grow in the hostile hypoxic tumor environment. Increased tumor HIF-1α has been correlated with increased angiogenesis, aggressive tumor growth, and poor patient prognosis, leading to the current interest in HIF-1α as a cancer drug target. A number of anticancer agents have been reported to decrease HIF-1α or HIF-1 transactivating activity in cells in culture. However, more relevant to the agents' antitumor activity is whether HIF-1 is inhibited in tumors in vivo. This has been demonstrated for only a few of the reported HIF-1 inhibitors. Some of the agents are moving toward clinical trial where it will be important to demonstrate that the agents inhibit HIF-1α in patient tumors or, failing this, the downstream consequences of HIF-1 inhibition such as decreased vascular endothelial growth factor formation, and relate this inhibition to antitumor activity. Only in this way will it be possible to determine if HIF-1α is a valid cancer drug target in humans.

Conjugated Linoleic Acid Inhibits Proliferation and Modulates Protein Kinase C Isoforms in Human Prostate Cancer Cells

Prostate cancer is the second most common cancer in men. The disease etiology is poorly understood, but diet and lifestyle are contributory factors. Conjugated linoleic acids (CLAs), naturally occurring fatty acids in ruminant food products, have antitumor properties in animal models of cancer and antiproliferative effects on cancer cells in vitro. The cellular mechanisms by which CLAs elicit these effects are unclear, particularly for prostate cancer cells. We have previously identified protein kinase C (PKC) isoforms, alpha, delta, iota, mu, and zeta in LNCaP prostate cancer cells. The objective of this study was to determine the effects of CLAs (individual cis-9, trans-11 and trans-10, cis-12 isoforms and a 50:50 mixture) on PKC isoform abundance in LNCaP cells. Confluent cells were treated with 6, 25, and 50 microM CLA for 0.5, 6, and 24 h. Cytosol and membrane protein fractions were assayed for PKC isoforms (mainly alpha and delta but also iota, mu, and zeta) by Western blot analysis using specific antibodies. CLAs clearly modulated the abundance of these PKC isoforms, both positively and negatively, depending on the isoform, concentration of CLAs, and period of treatment. Increased PKC-delta and decreased PKC-iota membrane abundance was consistent with CLAs eliciting increased apoptosis and, in part, with their antitumor effects.

HIFs and tumors--causes and consequences

For most organisms oxygen is essential fo life. When oxygen levels drop below those required to maintain the minimum physiological oxygen requirement of an organism or tissue it is termed hypoxia. To counter act possible deleterious effects of such a state, an immediate molecular response is initiated causing adaptation responses aimed at cell survival. This response is mediated by the hypoxia-inducible factor-1 (HIF-1), which is a heterodimer consisting of an alpha- and a beta-subunit. HIF-1 alpha protein is stabilized under hypoxic conditions and therefore confers selectivity to this response. Hypoxia is characteristic of tumors, mainly because of impaired blood supply resulting from abnormal growth. Over the past few years enormous progress has been made in the attempt to understand how the activation of the physiological response to hypoxia influences neoplastic growth. In this review some aspects of HIF-1 pathway activation in tumors and the consequences for pathophysiology and treatment of neoplasia are discussed.

ARK5 expression in colorectal cancer and its implications for tumor progression

A novel member of the human AMPK family, ARK5, was recently discovered to be a key molecule in mediating cancer cell migration activity in human pancreas cancer cell line PANC-1, and its activation was found to be induced by Akt-dependent phosphorylation at Ser 600. DNA array analysis with 241 paired cDNAs from 13 different types of tumors and corresponding normal tissues derived from cancer patients revealed ARK5 overexpression in the samples of colorectal cancer. ARK5 expression was measured and an in vitro invasion assay was performed in six human colorectal cancer cell lines, WiDr, HCT-15, DLD-1, SW620, LoVo, and SW480, and since high invasion activity was concordant with higher ARK5 expression, ARK5 expression was examined in relation to tumor progression and metastatic activity in clinical samples. In 56 clinical samples of primary colorectal cancers and their liver metastases, higher ARK5 expression was observed in the samples from more advanced cases, and much higher expression was observed in the liver metastases. In situ hybridization analysis showed ARK5 overexpression in tumor cells. Based on these findings, we propose that ARK5 overexpression is involved in tumor progression of colon cancer clinically.

Abnormal angiogenesis in diabetes mellitus

The adverse long-term effects of diabetes mellitus have been well described and involve many organ systems. While diabetes management has largely focused on control of hyperglycemia, the presence of abnormalities of angiogenesis may cause or contribute to many of the clinical manifestations of diabetes. When compared with non-diabetic subjects, diabetics demonstrate vascular abnormalities of the retina, kidneys, and fetus. Diabetics have impaired wound healing, increased risk of rejection of transplanted organs, and impaired formation of coronary collaterals. In each of these conditions, and possibly in diabetic neuropathy as well, abnormalities of angiogenesis can be implicated in the pathogenesis. A perplexing feature of the aberrant angiogenesis is that excessive and insufficient angiogenesis can occur in different organs in the same individual. In this review, the clinical features, molecular mechanisms, and potential therapeutic options of abnormal angiogenesis in diabetes will be reviewed.

Antiangiogenic and antitumor effects of a protein kinase Cbeta inhibitor in human breast cancer and ovarian cancer xenografts

In cell culture, the compound 317615 2HCl, a potent inhibitor of VEGF-stimulated HUVEC proliferation, was not very effective against MX-1 breast cancer cells (IC50= 8.1 microM) or SKOV-3 ovarian carcinoma cells (IC50 = 9.5 microM). Exposure to combinations of paclitaxel or carboplatin and 317615 x 2HCl with MX-1 cells in culture resulted in cell survival that reflected primarily additivity of the two agents. Exposure of SKOV-3 cells to paclitaxel or carboplatin along with 317615 2HCl resulted in cell survivals that reflected additivity of 317615 x 2HCl with paclitaxel and greater-than-additive cytotoxicity with carboplatin. Administration of 317615 x 2HCI orally twice daily to nude mice bearing subcutaneous MX-1 tumors or SKOV-3 tumors resulted in a decreased number of intratumoral vessels as determined by CD31 and CD105 staining with decreases of 35% and 43% in MX-1 tumors and 60% and 75% in SKOV-3 tumors, respectively. 317615 x 2HCl was an active antitumor agent against the MX-1 xenograft and increased the tumor growth delay produced by paclitaxel by 1.7-fold and the tumor growth delay produced by carboplatin by 3.8-fold. Administration of 317615 x 2HCl also increased the tumor growth delay produced by fractionated radiation therapy in the MX-1 tumor. Treatment with 317615 x 2HCl alone increased the lifespan of animals bearing intraperitoneal SKOV-3 xenografts by 1.9 fold compared with untreated control animals. The combination of paclitaxel and 317615 x 2HCl resulted in 100% 120-day survival of SKOV-3 bearing animals. Administration of 317615 x 2HCl along with carboplatin to animals bearing the SKOV-3 tumor produced a 1.8-fold increase in lifespan compared with carboplatin alone. 317615 x 2HCl is a promising new antiangiogenic agent that is in early phase clinical testing.

Hypoxia-inducible factor (HIF1A and HIF2A), angiogenesis, and chemoradiotherapy outcome of squamous cell head-and-neck cancer

PURPOSE

Hypoxia-inducible factors HIF1alpha and HIF2alpha (HIFalphas) regulate the expression of a variety of genes encoding proteins related to angiogenesis and to anaerobic metabolism of cells exposed to hypoxic stress. Their putative role as markers of clinically relevant hypoxia and, therefore, as predictors of response to chemoradiotherapy is herein examined.

PATIENTS AND METHODS

Using immunohistochemistry, we assessed the expression of HIFalphas in normal head-neck mucosa and in 75 cancer specimens from patients with locally advanced squamous cell head-and-neck cancer (SCHNC), treated with concurrent carboplatin chemoradiotherapy.

RESULTS

Head-and-neck mucosa from normal individuals did not show any HIF1alpha or HIF2alpha reactivity. SCHNC showed a varying expression of HIFalphas ranging through negative reactivity, to weak or focally strong cytoplasmic reactivity, or to strong diffuse cytoplasmic/nuclear reactivity. Fifty-two percent and 33% of cancer samples showed the latter expression pattern for HIF1alpha and HIF2alpha, respectively, and were considered to bear "high" HIF reactivity. Bone/cartilage involvement was more frequent in tumors with high HIF1alpha expression (p = 0.05). HIF1alpha and HIF2alpha overexpression were significantly associated with high microvessel density (p = 0.002 and 0.02, respectively) and with VEGF expression (p = 0.01 and 0.005, respectively). HIF1alpha was related to high thymidine phosphorylase expression (p = 0.03), whereas VEGF/KDR-activated tumor vasculature was significantly more frequent in HIF2alpha-overexpressing tumors (p = 0.02). High HIF1alpha and HIF2alpha were associated with incomplete response to chemoradiation (p = 0.007 and p = 0.02, respectively). In univariate analysis, high HIF1alpha and HIF2alpha expression were significantly associated with poor local relapse-free survival (p = 0.003 and 0.003, respectively) and with poor overall survival (p = 0.05 and 0.001, respectively). In multivariate models, HIF2alpha expression was an independent prognostic factor. In biopsies performed after the delivery of 20 Gy of radiotherapy, upregulation of HIFalphas was noted in some cases.

CONCLUSIONS

It is concluded that the overexpression of HIFalphas in SCHNC is related to locally aggressive behavior, to intensification of angiogenesis, and to an important resistance to carboplatin chemoradiotherapy.

Fatty Acid Regulation of Protein Kinase C Isoforms in Prostate Cancer Cells

Polyunsaturated fatty acids influence the aetiology of prostate cancer. Their effects on cellular mechanisms regulating prostate tumorigenesis are unclear. Using prostate cancer cells (LNCaP), we determined effects of n-9-OA, n-6-LA, and n-3-EPA on total PKC and its isoforms in relation to cell proliferation and PSA production. PKC-alpha, delta, gamma, iota, mu, and zeta were present in LNCaP cells; PKC-beta, epsilon, eta, and theta isoforms were not. PKC-alpha was detected only in cytosol; PKC-delta, iota, gamma, and mu were present in cytosol and in membranes. Fatty acids increased cell proliferation, total PKC activity and elicited pro-proliferative effects on specific PKC isoforms (PKC-delta and -iota). EPA and LA increased total PKC activity and reduced membrane-abundance of PKC-delta. OA reduced cytosolic and membrane PKC-delta. Only EPA reduced PKC-gamma membrane abundance. Fatty acids enhanced cytosolic PKC-iota abundance but only EPA and to a lesser extent LA increased its membrane content. Changes in PKC-delta, -iota, and -gamma did not affect PSA production.

Levels of hypoxia-inducible factor-1 alpha during breast carcinogenesis

BACKGROUND

Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that regulates gene expression in critical pathways involved in tumor growth and metastases. In this report, we investigated whether the level of HIF-1 alpha is increased during carcinogenesis in breast tissue and is associated with other tumor biomarkers.

METHODS

Paraffin-embedded clinical specimens from five pathologic stages of breast tumorigenesis and from normal breast tissue were used. HIF-1 alpha protein and the biomarkers vascular endothelial growth factor (VEGF), HER-2/neu, p53, Ki-67, and estrogen receptor (ER) were identified immunohistochemically, and microvessel density (a measure of angiogenesis) was determined. Associations among levels of HIF-1 alpha and these biomarkers were tested statistically. All statistical tests are two-sided.

RESULTS

The frequency of HIF-1 alpha-positive cells in a specimen increased with the specimen's pathologic stage (P<.001, chi(2) test for trend) as follows: normal breast tissue (0 specimens with > or = 1% HIF-1 alpha-positive cells in 10 specimens tested), ductal hyperplastic lesions (0 in 10), well-differentiated ductal carcinomas in situ (DCIS) (11 in 20), well-differentiated invasive breast cancers (12 in 20), poorly differentiated DCIS (17 in 20), and poorly differentiated invasive carcinomas (20 in 20). Increased levels of HIF-1 alpha were statistically significantly associated with high proliferation and increased expression of VEGF and ER proteins. In DCIS lesions, increased levels of HIF-1 alpha were statistically significantly associated with increased microvessel density. HIF-1alpha showed a borderline association with HER-2/neu but no association with p53.

CONCLUSIONS

The level of HIF-1 alpha increases as the pathologic stage increases and is higher in poorly differentiated lesions than in the corresponding type of well-differentiated lesions. Increased levels of HIF-1 alpha are associated with increased proliferation and increased expression of ER and VEGF. Thus, increased levels of HIF-1 alpha are potentially associated with more aggressive tumors.

Cell death beyond apoptosis

Though the term apoptosis was originated in pathology and developmental biology as an alternative to necrosis, the tissue necrosis with inflammation is irrelevant to cell culture conditions where apoptosis is mostly studied. Furthermore, no one single morphological feature is either necessary or sufficient to define apoptosis. The emerging biochemical definition, a cell death with caspase activation, allows the distinction of alternative forms of cell death. Thus, inhibition of caspases delays but does not prevent cell death. Slow cell death without caspase activation may nevertheless be associated with DNA fragmentation. Oncogenic Ras, Raf, and mitogen-activated kinases inhibit apoptosis by affecting the cytochrome C/caspase-9 pathway but may arrest growth and cause slow cell death with delayed DNA fragmentation. Such 'slow' cell death without caspase activation is often caused by chemotherapeutic drugs. Whether a cell will undergo apoptosis or slow death depends not only on a chemotherapeutic agent but also on the readiness of cellular caspases. Therefore, one can distinguish apoptosis-prone (eg leukemia) vs apoptosis-resistant cells. Cell susceptibilities to spontaneous, starvation-induced and drug-induced apoptosis are correlated and characterize an apoptosis-prone phenotype. Finally, distinction of slow cell death allows rephrasing of a question regarding the goal of cancer therapy: apoptosis vs slow cell death, or cancer cell-selectivity regardless of the mode of cell death.