Stress can alter immunological, neurochemical and endocrinological functions, but its role in cancer progression is not well understood. Here, we show that chronic behavioral stress results in higher levels of tissue catecholamines, greater tumor burden and more invasive growth of ovarian carcinoma cells in an orthotopic mouse model. These effects are mediated primarily through activation of the tumor cell cyclic AMP (cAMP)-protein kinase A (PKA) signaling pathway by the beta(2) adrenergic receptor (encoded by ADRB2). Tumors in stressed animals showed markedly increased vascularization and enhanced expression of VEGF, MMP2 and MMP9, and we found that angiogenic processes mediated the effects of stress on tumor growth in vivo. These data identify beta-adrenergic activation of the cAMP-PKA signaling pathway as a major mechanism by which behavioral stress can enhance tumor angiogenesis in vivo and thereby promote malignant cell growth. These data also suggest that blocking ADRB-mediated angiogenesis could have therapeutic implications for the management of ovarian cancer.

Erlotinib (Tarceva), an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, has clinical activity in advanced lung cancer, but disease that initially responds to erlotinib eventually progresses. The mechanism of this acquired resistance is unclear. We established two erlotinib-resistant pools of A-431 cells, a well-characterized epidermoid cancer cell line that constitutively overexpresses EGFR and is sensitive to erlotinib, by continuous exposure to erlotinib over a 6-month period. The extent of EGFR gene amplification or mutation of the EGFR tyrosine kinase domain was not altered in the resistant cells. Intracellular erlotinib concentrations, determined by liquid chromatography-tandem mass spectrometry, were almost the same in all three cell lines. Immunoprecipitation with EGFR antibody followed by detection with phosphotyrosine antibody revealed that erlotinib effectively reduced EGFR phosphorylation in both parental cells and resistant cells. Erlotinib induced mutated in multiple advanced cancers 1/phosphatase and tensin homologue (MMAC1/PTEN) and suppressed phosphorylated Akt (Ser(473)) but not in the erlotinib-resistant cells. Overexpression of MMAC1/PTEN by transfection with Ad.MMAC1/PTEN or by pharmacologic suppression of Akt activity restored erlotinib sensitivity in both resistant pools. Further, transfection of parental A-431 cells with constitutively active Akt was sufficient to cause resistance to erlotinib. We propose that acquired erlotinib resistance associated with MMAC1/PTEN down-regulation and Akt activation could be overcome by inhibitors of signaling through the phosphatidylinositol 3-kinase pathway.

We investigated the formation and pharmacology of prostaglandin E 3 (PGE 3 ) derived from fish oil eicosapentaenoic acid (EPA) in human lung cancer A549 cells. Exposure of A549 cells to EPA resulted in the rapid formation and export of PGE 3. The extracellular ratio of PGE 3 to PGE 2 increased from 0.08 in control cells to 0.8 in cells exposed to EPA within 48 h. Incubation of EPA with cloned ovine or human recombinant cyclooxygenase 2 (COX-2) resulted in 13-and 18-fold greater formation of PGE 3 , respectively, than that produced by COX-1. Exposure of A549 cells to 1 M PGE 3 inhibited cell proliferation by 37.1% ( P Ͻ 0.05). Exposure of normal human bronchial epithelial (NHBE) cells to PGE 3 , however, had no effect. When A549 cells were exposed to EPA (25 M) or a combination of EPA and celecoxib (a selective COX-2 inhibitor), the inhibitory effect of EPA on the growth of A549 cells was reversed by the presence of celecoxib (at both 5 and 10 M). This effect appears to be associated with a 50% reduction of PGE 3 formation in cells treated with a combination of EPA and celecoxib compared with cells exposed to EPA alone. These data indicate that exposure of lung cancer cells to EPA results in a decrease in the COX-2-mediated formation of PGE 2 , an increase in the level of PGE 3 , and PGE 3 -mediated inhibition of tumor cell proliferation. 2)]. Epidemiologic studies have shown an inverse relationship between blood levels of n-3 fatty acids derived from fish oils and the risk of prostate and lung cancers (3-5). However, molecular mechanisms for the pharmacologic anticancer activity of EPA have not been fully elucidated. A number of studies have suggested that the anticancer activities of both EPA and DHA are associated with their ability to inhibit the synthesis of 2-series prostaglandins, especially prostaglandin E 2 (PGE 2 ) production [as reviewed in ref. (6)]. In contrast to DHA, however, EPA can actually function as a substrate for COX and result in the synthesis of unique 3-series prostaglandin compounds (7). To date, studies reporting the formation of 3-series prostaglandins by EPA have been performed using normal cells or tissues (8,9). Fischer and Weber (10), for example, provided the first evidence of in vivo formation of thromboxane A 3 and prostaglandin I 3 in humans fed fish oil. In addition, studies conducted in humans have shown that PGE 3 levels increased by ‫ف‬ 10-fold in urine after ingestion of cod liver oil (40 ml/day) for 12 weeks (11).In contrast to PGE 2 , the biological activity of PGE 3 has received little attention. The effect of PGE 3 on cell growth has been reported only in normal murine mammary epithelial (12) and 3T3 fibroblast cells (13). Both studies showed that PGE 2 and PGE 3 stimulated the growth of norAbbreviations: AA, arachidonic acid; BHT, butylated hydroxytoluene; calcein AM, acetoxymethyl ester of calcein; COX, cyclooxygenase; DAPI, 4 Ј ,6-diamidino-2-phenylindole; DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid; LC/MS/MS, liquid chromatography/tandem mass sp...

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Summary:We investigated whether adjusting the oral busulfan (BU) dosage on the basis of early pharmacokinetic data to achieve a targeted drug exposure could reduce transplant-related complications in children with advanced hematologic malignancies. Twenty-five children received a preparative regimen consisting of thiotepa (250 mg/m 2 i.v. daily for 3 days), BU (40 mg/m 2 per dose p.o. every 6 h for 12 doses), and cyclophosphamide (60 mg/kg i.v. daily for 2 days) and then underwent allogeneic stem cell transplantation. Busulfan clearance and area under concentration time-curve (AUC) were determined after the first dose using a one-compartment pharmacokinetic (PK) model with first-order absorption. The initial PK analysis was successfully completed after the first BU dose in 21 patients (84%). A final AUC of 1000-1500 m × min/dose was targeted and subsequent doses were modified as necessary to achieve this value. Fourteen of the 25 patients (56%) required dose adjustment. Followup PK analysis was completed in 21 patients and 16 of these achieved the targeted BU exposure for the course of therapy. Interpatient variability in BU clearance was high (up to five-fold). The most frequent regimenrelated toxicities were cutaneous and gastrointestinal (stomatitis and diarrhea). Only one patient developed hepatic veno-occlusive disease. Our study demonstrates the feasibility of adjusting the oral BU dose in individual pediatric patients. Although toxicity associated with BU seemed to be reduced, this conclusion is tempered by the fact that the overall regimen-related toxicity (RRT) remains substantial and reflected the effects of all agents used in the preparative regimen. Bone Marrow Transplantation (2000) 26, 463-470.