One-pot heterogeneous synthesis of Δ(3)-tetrahydrocannabinol analogues and xanthenes showing differential binding to CB(1) and CB(2) receptors

Δ(9)-tetrahydrocannabinol (Δ(9)-THC) is the major psychoactive cannabinoid in hemp (Cannabis sativa L.) and responsible for many of the pharmacological effects mediated via cannabinoid receptors. Despite being the major cannabinoid scaffold in nature, Δ(9)-THC double bond isomers remain poorly studied. The chemical scaffold of tetrahydrocannabinol can be assembled from the condensation of distinctly substituted phenols and monoterpenes. Here we explored a microwave-assisted one pot heterogeneous synthesis of Δ(3)-THC from orcinol (1a) and pulegone (2). Four Δ(3)-THC analogues and corresponding Δ(4a)-tetrahydroxanthenes (Δ(4a)-THXs) were synthesized regioselectively and showed differential binding affinities for CB1 and CB2 cannabinoid receptors. Here we report for the first time the CB1 receptor binding of Δ(3)-THC, revealing a more potent receptor binding affinity for the (S)-(-) isomer (hCB1Ki = 5 nM) compared to the (R)-(+) isomer (hCB1Ki = 29 nM). Like Δ(9)-THC, also Δ(3)-THC analogues are partial agonists at CB receptors as indicated by [(35)S]GTPγS binding assays. Interestingly, the THC structural isomers Δ(4a)-THXs showed selective binding and partial agonism at CB2 receptors, revealing a simple non-natural natural product-derived scaffold for novel CB2 ligands.

Stimulation of monocytes by placental microparticles involves toll-like receptors and nuclear factor kappa-light-chain-enhancer of activated B cells.

Human pregnancy is accompanied by a mild systemic inflammatory response, which includes the activation of monocytes circulating in maternal blood. This response is exaggerated in preeclampsia, a placental-dependent disorder specific to human pregnancies. We and others showed that placental syncytiotrophoblast membrane microparticles (STBM) generated in vitro from normal placentas stimulated peripheral blood monocytes, which suggest a contribution of STBM to the systemic maternal inflammation. Here, we analyzed the inflammatory potential of STBM prepared from preeclamptic placentas on primary monocytes and investigated the mode of action in vitro. STBM generated in vitro by placental villous explants of normal or preeclamptic placentas were co-incubated with human peripheral blood monocytes. In some cases, inhibitors of specific cellular functions or signaling pathways were used. The analysis of the monocytic response was performed by flow cytometry, enzyme-linked immunoassays, real-time PCR, and fluorescence microscopy. STBM derived from preeclamptic placentas up-regulated the cell surface expression of CD54, and stimulated the secretion of the pro-inflammatory interleukin (IL)-6 and IL-8 in a similar, dose-dependent manner as did STBM prepared from normal placentas. STBM bound to the cell surface of monocytes, but phagocytosis was not necessary for activation. STBM-induced cytokine secretion was impaired in the presence of inhibitors of toll-like receptor (TLR) signaling or when nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation was blocked. Our results suggest that the inflammatory reaction in monocytes may be initiated by the interaction of STBM with TLRs, which in turn signal through NF-κB to mediate the transcription of genes coding for pro-inflammatory factors.

Nck-interacting Ste20 kinase couples Eph receptors to c-Jun N-terminal kinase and integrin activation.

The mammalian Ste20 kinase Nck-interacting kinase (NIK) specifically activates the c-Jun amino-terminal kinase (JNK) mitogen-activated protein kinase module. NIK also binds the SH3 domains of the SH2/SH3 adapter protein Nck. To determine whether Nck functions as an adapter to couple NIK to a receptor tyrosine kinase signaling pathway, we determined whether NIK is activated by Eph receptors (EphR). EphRs constitute the largest family of receptor tyrosine kinases (RTK), and members of this family play important roles in patterning of the nervous and vascular systems. In this report, we show that NIK kinase activity is specifically increased in cells stimulated by two EphRs, EphB1 and EphB2. EphB1 kinase activity and phosphorylation of a juxtamembrane tyrosine (Y594), conserved in all Eph receptors, are both critical for NIK activation by EphB1. Although pY594 in the EphB1R has previously been shown to bind the SH2 domain of Nck, we found that stimulation of EphB1 and EphB2 led predominantly to a complex between NIK/Nck, p62(dok), RasGAP, and an unidentified 145-kDa tyrosine-phosphorylated protein. Tyrosine-phosphorylated p62(dok) most probably binds directly to the SH2 domain of Nck and RasGAP and indirectly to NIK bound to the SH3 domain of Nck. We found that NIK activation is also critical for coupling EphB1R to biological responses that include the activation of integrins and JNK by EphB1. Taken together, these findings support a model in which the recruitment of the Ste20 kinase NIK to phosphotyrosine-containing proteins by Nck is an important proximal step in the signaling cascade downstream of EphRs.

Neurotensin receptors in pancreatic ductal carcinomas.

BACKGROUND The frequent expression of neurotensin receptors (NT-R) in primaries of pancreatic ductal carcinomas has triggered the development of radioactive neurotensin analogs for possible in vivo targeting of these tumors. However, the complete lack of information regarding NT-R in liver metastases of pancreatic cancer and pancreatic intraepithelial neoplasia (PanIN) makes an in vitro study of NT-R in these tissues indispensable. METHODS Using in vitro receptor autoradiography with (125)I-[Tyr(3)]-neurotensin, NT-R were investigated in 18 primaries and 23 liver metastases of pancreatic ductal carcinomas as well as in 19 PanIN lesions. RESULTS We report here that 13 of 18 ductal carcinoma primaries and 14 of 23 liver metastases expressed NT-R. Moreover, none of the six PanIN 1B cases expressed NT-R, while two of six PanIN 2 and five of seven PanIN 3 expressed NT-R. Binding was fully displaced by the type 1 NT-R-selective antagonist SR48692, indicating that the NT-R in the tumors are of the type 1 NT-R subtype. CONCLUSIONS These in vitro data extend the currently available information on NT-R in invasive and non-invasive pancreatic ductal tumors. They suggest that type 1 NT-R may be a novel, specific marker of PanIN of higher degree. The high expression of NT-R in primaries and metastases of invasive cancer strongly support the need to develop radioactive neurotensin analogs for the diagnosis and therapy of this tumor type.

Modulatory Effects of Eschscholzia californica Alkaloids on Recombinant GABAA Receptors.

The California poppy (Eschscholzia californica Cham.) contains a variety of natural compounds including several alkaloids found exclusively in this plant. Because of the sedative, anxiolytic, and analgesic effects, this herb is currently sold in pharmacies in many countries. However, our understanding of these biological effects at the molecular level is still lacking. Alkaloids detected in E. californica could be hypothesized to act at GABAA receptors, which are widely expressed in the brain mainly at the inhibitory interneurons. Electrophysiological studies on a recombinant α 1 β 2 γ 2 GABAA receptor showed no effect of N-methyllaurotetanine at concentrations lower than 30 μM. However, (S)-reticuline behaved as positive allosteric modulator at the α 3, α 5, and α 6 isoforms of GABAA receptors. The depressant properties of aerial parts of E. californica are assigned to chloride-current modulation by (S)-reticuline at the α 3 β 2 γ 2 and α 5 β 2 γ 2 GABAA receptors. Interestingly, α 1, α 3, and α 5 were not significantly affected by (R)-reticuline, 1,2-tetrahydroreticuline, codeine, and morphine-suspected (S)-reticuline metabolites in the rodent brain.

Platelet receptors and patient responses: The contributions of Professor Stan Heptinstall to platelet research.

Stan Heptinstall's contributions to platelet research covered organising meetings at the national and European level as well as starting and maintaining the journal "Platelets". The major part of his research addressed problems of inhibition of platelet receptors and the effects of this on patient health. In particular, the effects of P2Y12 inhibitors on patients with acute cardiovascular problems were a major focus. Other studies included the effects of feverfew (Tanacetum parthenium) extracts on platelets, of direct anti-IIb/IIIa receptor (αIIbβ3) inhibitors and of prostanoids on platelet function. Recently, methods for assessing the effectiveness of platelet inhibition were investigated.

Is sensitization to stimulants time dependent and mediated via NMDA receptors?

Chronic administration of psychomotor stimulants has been reported to produce behavioral sensitization to its effects on motor activity. This adaptation may be related to the pathophysiology of recurrent psychiatric disorders. Since disturbances in circadian rhythms are also found in many of these disorders, the relationship between sensitization and chronobiological factors became of interest. Therefore, a computerized monitoring system investigated the following: whether repeated exposure to methylphenidate (MPD) and amphetamine (AMP) could produce sensitization to its locomotor effects in the rat; whether sensitization to MPD and AMP was dependent on the circadian time of drug administration; whether the baseline levels of locomotor activity would be effected by repeated exposure to MPD and AMP; whether the expression of a sensitized response could be affected by the photoperiod; and whether MK-801, a non-competitive NMDA antagonist, could disrupt the development of sensitization to MPD. Dawley rats were housed in test cages and motor activity was recorded continuously for 16 days. The first 2 days served as baseline for each rat, and on day 3 each rat received a saline injection. The locomotor response to 0.6, 2.5, or 10 mg/kg of MPD was tested on day 4, followed by five days of single injections of 2.5 mg/kg MPD (days 5–9). After five days without injection (days 10–14) rats were re-challenged (day 15) with the same doses they received on day 4. There were three separate dose groups ran at four different times of administration, 08:00, 14:00, 20:00, or 02:00 (i.e. 12 groups). The same protocol was conducted with AMP with the doses of 0.3, 0.6, and 1.2 mg/kg given on day 4 and 15, and 0.6 mg/kg AMP as the repeated dose on days 5 to 9. In the second set of experiments only sensitization to MPD was investigated. The expression of the sensitized response was dose-dependent and mainly observed with challenge of the lower dose groups. The development of sensitization to MPD and ANT was differentially time-dependent. For MPD, the most robust sensitization occurred during the light phase, with no sensitization during the middle of the dark phase. (Abstract shortened by UMI.) ^

Na 1 Nachlass Max Horkheimer, 656 - Dokumente zur Geschichte des Instituts für Sozialforschung (p. IX 49a-IX 55.1-5)

Max Horkheimer: Über Wissenschaft und Technologie in Israel. Begrüßungsrede für Mr. Ben Sira, gehalten am 8.1.1949; 1. Notizen zur Rede, 10 Blatt; 2. David Ben Gurion, "Science and Technology in Israel", Sonderdruck, 2 Blatt; Über die Antisemitismus-Forschungen des Instituts für Sozialforschung. Protokoll einer Sitzung der Frankfurter Gesellschaft für Christlich-Jüdische Zusammenarbeit, 16.Mai 1949. Typoskript (Kopie), 2 Blatt; Max Horkheimer: Über Arbeit und Pläne des Instituts für Sozialforschung in Frankfurt. Vortrag, gehalten 1949 in Frankfurt (Clubabend). Manuskript, 3 Blatt; Zur Begründung eines Instituts für Sozialforschung, 1922; 1. Senckenbergische Naturforschende Gesellschaft, Frankfurt: 1 Brief mit Unterschrift (Kopie) an die Universität Frankfurt, Kuratorium, Frankfurt, 22.8.1922; 2. Felix Weil und Kurt Albert Gerlach: "Denkschrift über die Begründung eines Instituts für Sozialforschung" (1922). Typoskript (Kopie), 5 Blatt; Carl Grünberg: Festrede, gehalten zur Einweihung des Instituts für Sozialforschung an der Universität Frankfurt am Main, am 22.6.1924. a) Kopie (Auszug) aus dem Abdruck der Rede in Frankfurter Universitätsreden 1924, 3 Blatt b) Sonderdruck Frankfurter Universitätsreden 1924, 16 Seiten; Darstellungen des Instituts für Sozialforschung (1925-51); 1. Gesellschaft für Sozialforschung, Frankfurt: "Institut für Sozialforschung an der Universität Frankfurt am Main". Sonderdruck (Kopie), Frankfurt, 1925, 29 Seiten; 1a. Hermann Weil: "Bericht über das Heimatfest in Waibstadt am 3. und 4. September und die feierliche Übergabge meines Mausoleums in den Schutz der Stadt Waibstadt". Sonderdruck, 1927, 7 Seiten; 1b. Felix Weil, 1 Brief mit Unterschrift (Kopie) an den Minister für Wissenschaft, Kunst und Volksbildung Berlin. Frankfurt, 1.11.1929, Typoskript, 31 Blatt; 1c. Columbia University: "Report of the President of Columbia University for 1934" (darin S.7: Erwähnung des Instituts für Sozialforschung und der Zeitschrift für Sozialforschung), Sonderdruck, New York, 1934, 80 Seiten; 2. "International Institute of Social Research: A short Description of Its History and Aims", New York 1935, Sonderdruck, 15 Seiten; 3. Briefbogen des Instituts für Sozialforschung mit den Namen des Research Staff und des Advisory Committee, 1 Blatt; 4. "International Institute of Social Research. A Report On Its History, Aims and Activities 1933-1938". Sonderdruck, New York 1939, 36 Seiten; 5. "Research Bureau For Post-War Economics and Its Cooperating Institutions. Annual Repost", Sonderdruck, New York, Mai 1939, 17 Seiten; 5a. Los Angeles University of Applied Education: "General Catalogue 1947-48" (mit Erwähnungen des Instituts für Sozialforschung bzw. von Mitarbeitern), Druck, 56 Seiten; 6. Einladung zur Eröffnung des Instituts für Sozialforschung am 14. November 1951. Sonderdruck, Frankfurt 1951, 2 Blatt; Über das Institut für Sozialforschung 1924-31. Tabellarische Zusammenstellung, 1931, Typoskript mit eigenhändigen und handschriftlichen Ergänzungen, 5 Blatt; Max Horkheimer: "Die gegenwärtige Lage der Sozialphilosophie und die Aufgaben eines Instituts für Sozialforschung". Öffentliche Antrittsvorlesung bei Übernahme des Lehrstuhls für Sozialphilosophie und der Leitung des Instituts für Sozialforschung, 24.1.1931, Kopie (Auszug) aus dem Abdruck der Rede in Frankfurter Universitätsreden 1931, 4 Blatt; "History and Program of the Institute of Social Research". Veröffentlicht unter dem Titel "International Institute of Social Research. A Short Description of Its History and Aims", New York (1934 od. 1935), Typoskript, 6 Blatt.; "A Digest of the History, Program and Needs of the International Institute of Social Research". 1934, als Typoskript vervielfältigt, 4 Blatt; Julian Gumperz: "Notes for a talk", Über Ziele und Methoden der Arbeit des Instituts für Sozialforschung, 1934. Typoskript mit handschriftlicher Korrektur, 10 Blatt; "Report of the President of Columbia University for the year ending June 30, 1934".Auszug daraus, 1934, Typoskript, 1 Blatt; Über Geschichte und Tätigkeiten des Instituts für Sozialforschung. Verschiedene Berichte, ca. 1934-1937: 1. Über Geschichte, Tätigkeiten und Ziele des Instituts, nicht vor 1934, Typoskript, 5 Blatt; 2. Bericht an den Präsidenten der Columbia University, 14.3.1936, Typoskript, 2 Blatt; 3. "Dr. Horkheimer's Paper Delivered on the Occasion of an Institute Luncheon Given to the Faculty of Social Sciences of Columbia University on January 12th, 1937". Typoskript, 13 Blatt; 4. Bericht an den Präsidenten der Columbia University. 18.3.1937, Typoskript, 3 Blatt; 5. Über Programm, Mitglieder und Tätigkeiten des Instituts, 1937, a) Typoskript, 2 Blatt, b) Entwurf, Typoskript, 4 Blatt; 6. Publikationsliste 1937, Typoskript, 1 Blatt; Über "Autorität und Familie" und die "Zeitschrift für Sozialforschung". 1937, Typoskript, französisch, mit eigenhändigen Korrekturen, 4 Blatt; Max Horkheimer: Über das Institut für Sozialforschung 1938: 1. Typoskript, englische Fassung, mit handschriftlichen Korrekturen, 38 Blatt; 2. Typoskript, deutsche Fassung mit eigenhändigen Korrekturen, 37 Blatt (G.S. 12, S. 132-164); 3. Julian Gumperz: 1 Brief an Herbert Marcuse, New York, 30.8.1938; 4. Teilstück aus früherer Fassung (?), Typoskript, 1 Blatt, 5. Entwurf zu 2., a) Typoskript, 1 Blatt, b) Typoskript mit eigenhändigen Korrekturen und Ergänzungen, 2 Blatt;

Na 1 Nachlass Max Horkheimer, 661 - Berichte über die Arbeit des Instituts für Sozialforschung, "Research-Project on Anti-Semitism" u.a. (p. IX 78-IX 92.1a)

"Institut für Sozialforschung: Research Projects", Tabellarische Zusammenstellung (Juni 1953), Typoskript, 2 Blatt; "Institut für Sozialforschung an der Johann Wolfgang Goethe-Universität Frankfurt, Germany: Memorandum" (1953), a) Typoskript, 12 Blatt, b) Typoskript, 13 Blatt; "Projects of the Institute for Social Research" (1.7.1954), Typoskript, 5 Blatt; "Institut für Soziaforschung: Mitteilungen an die Presse" (November 1955), als Typoskript vervielfältigt, 6 Blatt; Clark: "Institut für Sozialforschung an der Johann Wolfgang Goethe-Universität in Frankfurt am Main" (etwa 1955), Typoskript, englisch, mit handschriftlichen Korrekturen, unter anderem von Max Horkheimer, 2 Blatt; "Institut für Sozialforschung" (6.3.1958), a) als Typoskript vervielfältigt, 10 Blatt, b) Typoskript, 22 Blatt, c) Kurzfassung, Typoskript, 3 Blatt, d) Teilstück, Typoskript, 1 Blatt, e) Sonderdruck, 15 Seiten; Abgeschlossene und laufende Arbeiten des Instituts. Tabellarische Zusammenstellung (1958?), Typoskript, 1 Blatt; "Laufende Studien" Tabellarische Aufstellung (25.5.1961), Typoskript, 1 Blatt; Friedrich Pollock (?): Anmerkungen zu Paul Klukes Darstellung des Instituts für Sozialforschung in dessen "Geschichte der Frankfurter Universität" (8.9.1969), Typoskript mit handschriftlichen Korrekturen, 4 Blatt; Theodor W. Adorno: Über die Arbeiten des Instituts für Sozialforschung (Datierung unklar, etwa 1941-45), Teilstück eines Entwurfs, Typoskript mit eigenhändiger Korrektur, 2 Blatt; Über die wesentliche Aufgabe des Instituts: Vereinigung geisteswissenschaftlicher und empirischer Methoden (Datierung unklar), Typoskript, 1 Blatt; "Forschungsprojekte des Instituts" (Datierung unklar, etwa 1950), Typoskript mit handschriftlichen Ergänzungen von Friedrich Pollock, 5 Blatt; "Vorträge im Institut für Sozialforschung. Einladungen und tabellarische Aufstellungen" (1953 u.a.), 5 Blatt; "Vorlesungen und Übungen im Institut für Sozialforschung, Ankündigungen aus den Jahren 1952-64, 9 Blatt; "International Institute of Social Research: Research-Project on Anti-Semitism" (1939-42) (veröffentlicht in Studies in Philosophy and Social Science Bd. IX, 1941, S. 124-143): 1. "Research Project on Anti-Semitism", a) Typoskript, 45 Blatt;

Spectroscopic and functional investigations of the AMPA subtype of ionotropic glutamate receptors

Ion channels play a crucial role in the functioning of different systems of the body because of their ability to bridge the cell membrane and allow ions to pass in and out of the cell. Ionotropic glutamate receptors are one class of these important proteins and have been shown to be critical in propagating synaptic transmission in the central nervous system and in other diverse functions throughout the body. Because of their wide-ranging effects, this family of receptors is an important target for structure-function investigations to understand their mechanism of action. ^ α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are one subtype of glutamate receptors and have been shown to be the primary receptors involved in rapid excitatory signaling in the central nervous system. Agonist binding to the extracellular ligand binding domain of these receptors causes various conformational changes that culminate in formation of the ion channel. Previous structural investigations have provided important information about their mechanism of action, including uncovering a relationship between the degree of cleft closure in the binding domain and activation of the receptor. However, what question remains unanswered is how specific interactions between the agonist and the protein interplay with cleft closure to mediate receptor activation. ^ To investigate this question, I applied a multiscale approach to investigate the effects of agonist binding on various levels. Vibrational spectroscopy was utilized to investigate molecular-level interactions in the binding pocket, and fluorescence resonance energy transfer (FRET) was employed to measure cleft closure in the isolated ligand binding domain. The results of these studies in the isolated binding domain were then correlated to activation of the full receptor. These investigations showed a relationship between the strength of the interaction at the α-amine group of the agonist and extent of receptor activation, where a stronger interaction correlated to a larger activation, which was upheld even when the extent of cleft closure did not correlate to activation. These results show that this interaction at the α-amine group is critical in mediating the allosteric mechanism of activation and provide a bit more insight into how agonist binding is coupled to channel gating in AMPA receptors. ^

Proliferation index in ductal carcinoma in situ of the breast: Relation to estrogen, progesterone and HER2/neu receptors

Background. Ductal carcinoma in situ (DCIS) is the most prevalent precursor to invasive breast cancer (IBC), the second leading cause of death in women in the United States. The three most important prognostic markers for IBC are Estrogen receptor (ER), Progesterone receptor (PR) and HER2/neu. The four groups (IBC) defined as (1) ER and/or PR positive and HER2/neu negative, (2) ER and/or PR positive and HER2/neu positive (3) ER and/or PR negative and HER2/neu positive and (4) negative for all three of these receptors (Triple negative). However, they have not been well studied in DCIS. This is an exploratory study with a primary objective to examine the prevalence of ER, PR, and HER2/neu in DCIS, to explore if the defined groups of IBC occur in DCIS and to consider the biological relationship between these four groups and the proliferative activity of the tumor. A secondary goal of this study is to examine the relationship between grade and proliferative activity. Methods. Using immunohistochemistry, I have measured Ki-67, ER, PR and HER2/neu positivity for a series of cases of DCIS. Results. 20 ER and/or PR positive and HER2/neu negative (50%) with average PI of 0.05, 7 ER and/or PR positive and HER2/neu positive (17.5%) with average PI of 0.14, 10 ER and/or PR negative and HER2/neu positive (25%) with average PI of 0.18, and three triple negative (7.5%) with average PI of 0.18. ER and/or PR positive and HER2/neu positive group has the highest PI (p<0.001). Further, the ER and/or PR positive and HER2/neu positive group show a linear relationship between PI and average ER/PR positivity (R=0.6). PI increases with higher grades. Conclusion. PI appears to depend upon the average fraction of positive ER/PR tumor cells, possibly with a synergistic dependence when HER2/neu is positive. If ER/PR is negative, then both HER2/neu positive and the triple negative cases appear to cluster around an average PI that is higher than the average PI in HER2/neu negative ER/PR positive negative cases. In the triple negative tumors there must be another driver of proliferation.^

Aberrant regulation of the Src -FAK signaling pathway in the human colon adenocarcinoma cell line HT-29

c-Src, a protein tyrosine kinase (PTK) the specific activity of which is increased $>$20-fold in $\sim$80% of colon tumors and colon tumor cell lines, plays a role in both growth regulation and tumorigenicity of colon tumor cells. To examine the effect of increased c-Src specific activity on colon tumor cells, coumarin-derived tyrosine analog PTK inhibitors were assessed in a standard colon tumor cell line, HT-29. Of the nine compounds tested for inhibiting c-Src activity in a standard immune complex kinase assay from c-Src precipitated from HT-29 cells, the 7,8-dihydroxy-containing compounds daphnetin and fraxetin were most effective, with IC$\sb{50}$s of 0.6 $\pm$ 0.2 mM and 0.6 $\pm$ 0.3 mM, respectively. Treatment of HT-29 cells with daphnetin resulted in inhibition of cell growth in a dose-dependent manner. In contrast, scopoletin, a relatively poor Src inhibitor in vitro, did not inhibit HT-29 cell growth in the concentration range tested. In daphnetin treated cells, a dose-dependent decrease of c-Src activity paralleling cell growth inhibition was also observed; the IC$\sb{50}$ was 0.3 $\pm$ 0.1 mM for c-Src autophosphorylation. In contrast, the IC$\sb{50}$ for c-Src protein level was $>$ 0.6 mM, indicating that the effects of daphnetin were primarily an enzymatic activity of c-Src, rather than protein level in HT-29 cells. These results are the first to demonstrate that c-Src specific activity regulates colon tumor cell growth.^ To elucidate the signaling pathways activated by c-Src in colon tumor cells, the Src family substrate FAK, which has been shown to play a role in both extracellular matrix-dependent cell growth and survival, was examined. Coprecipitation assays showed Src-FAK association in detergent insoluble fractions of both attached and detached HT-29 cells, indicating that Src-FAK association in HT-29 cells is stable and, unlike untransformed cells, not dependent on cell-substratum contact. FAK also coprecipitated with Grb2, an adaptor protein also playing a role in cell proliferation and survival, in both attached and detached HT-29 cells, suggesting that a Src-FAK-Grb2-mediated signaling pathway(s) in HT-29 cells is/are constitutively activated.^ FAK was also analyzed in c-src antisense HT-29 clones AS15 and AS33 in which c-Src is specifically reduced by transfection of an antisense expression vector. FAK protein level is unexpectedly decreased in both AS15 and AS33 cells by 5-fold and 1.5-fold compared to HT-29, respectively, corresponding with the decreased expression of c-Src observed in these cells. FAK protein level was not decreased compared to parental in the c-src "sense" clone S8. Northern blot analyses showed decreased FAK mRNA levels compared to parental in AS15 and AS33, correlating with decreased FAK protein level, indicating that FAK activity in the antisense cells is regulated, at least in part, by altering FAK expression, and that this regulation is Src dependent. Because FAK has been implicated in anoikis, the ability of c-src antisense cells to survive in the absence of cell-substratum contact was examined. Decreased cell survival is seen in both AS15 and AS33, correlating with the decreases in c-Src and FAK levels and tumorigenicity in these cells. These results suggest that at least one mechanism by which activation of c-Src contributes to tumorigenic phenotype of colon tumor cells is by aberrantly promoting a survival signal through unregulated Src-FAK-Grb2 complexes. (Abstract shortened by UMI.) ^