The cytochrome P-450 pathway is capable of metabolizing arachidonic acid to omega- and subterminal hydroxylase metabolites, 16-, 17-, 18-, 19-, and 20-hydroxyeicosatetraenoic acids (P-450 HETEs). We have quantitated, by gas chromatography-mass spectrometry (GC/MS), endogenous HETEs exiting the rabbit isolated perfused kidney elicited by hormonal stimulation. Kidneys were perfused with Krebs-Henseleit solution containing indomethacin (2.8 microM) to prevent further metabolism of HETEs by cyclooxygenase. Phenylephrine (2-3 microM) was added to the perfusate to raise perfusion pressure to approximately 80 mmHg. Angiotensin II (ANG II), arginine vasopressin (AVP), and bradykinin (BK) were injected into the renal artery and perfusates collected throughout the vasoactive response. After addition of an internal standard, deuterated 19-HETE, perfusates were extracted and purified and P-450 HETEs were derivatized for GC/MS analysis. Under basal conditions, 16-, 18-, 19-, and 20-HETEs were released (range: 50-270 pg/ml), 19-HETE being the highest and fivefold greater than 16-HETE, the lowest. Injection of 50 ng ANG II increased by two- to sixfold P-450 HETE release associated with an increase of 40 +/- 11 mmHg in perfusion pressure. An equipressor dose of AVP (50 ng) did not release P-450 HETEs nor did a 5-micrograms dose of the vasodilator peptide BK, which decreased perfusion pressure by 22 +/- 6 mmHg. Authentic 19- and 20-HETE isomers resulted in dose-dependent dilation, as did 18(R)- and 16(R)-HETEs, whereas their enantiomers and 17-HETE isomers were without effect on perfusion pressure. The vasodilator effects of 18(R)- and 16(R)-HETEs, like 20- and 19-HETEs, were inhibited by indomethacin. Furthermore, P-450 HETEs exhibited both regio- and stereoselective inhibition of proximal tubule adenosine triphosphatase (ATPase) activity. The (S) enantiomers of 16- and 17-HETE potently inhibited activity, whereas their (R) isomers and other P-450 HETEs had negligible effects on ATPase activity. The quantity of HETEs released from the kidney, either under basal conditions or when stimulated by ANG II, and their biological profile suggest that subterminal HETEs may participate in renal mechanisms affecting vasomotion and tubular transport.

Malignant tumor cells exhibit a number of distinct properties involved not only with deregulated cell proliferation but also enhanced migration and invasion. The Jun oncogene has been well studied in regard to its role in cell proliferation. Many of the target genes deregulated by Jun encode matrix metalloproteases (MMPs) such as MMP1, MMP3 and MMP9. These targets implicate a prominent role for Jun in tumor cell invasion, in addition to its role in growth transformation. To investigate this possibility, we have examined the effect of over-expression of transforming and non-transforming versions of Jun on motility and invasion of chicken embryo fibroblasts (CEFs). We found that over-expression of either form of Jun results in elevated intrinsic cellular motility as well as increased motility in response to several different chemoattractants, including 3T3-conditioned media, basic fibroblast growth factor, hepatocyte growth factor and Matrigel. The capacity of these cells to invade through Matrigel is also elevated as a result of Jun over-expression. In addition to these effects, CEFs expressing Jun secrete factors that stimulate the motility of a human tongue carcinoma cell line. Our results suggest that Jun plays an important role in the potentiation of cell motility and invasion through multiple mechanisms. Int.

Autocrine growth factors for the epidermal growth factor receptor (EGFR) have been identified in prostate tumors, implicating a role for EGFR in the progression of prostate cancer. To investigate early signaling mechanisms used by the EGFR in prostate tumor cells, we have characterized the involvement of the Shc (src homology 2/x‐collagen related) adapter protein in EGFR signaling in several human prostate tumor cell lines. In androgen‐responsive lymph node‐prostate cancer (LNCaP) cells and androgen‐insensitive PC3, DU145 and PPC‐1 cells, Shc was identified as one of the most prominent phosphotyrosine proteins to be elevated in response to EGF. Equivalent levels of the 46‐ and 52‐kDa Shc isoforms were detected in all of the tumor cell lines tested. However, levels of the 66‐kDa isoform were variable among the cell lines. In all of the tumor cell lines, EGF caused an association between Shc and Grb2, another adapter protein linked to cellular ras activation. Additionally, several phosphotyrosine proteins, including a 115–120‐kDa protein in EGF‐treated LNCaP cells, co‐associated with Shc. The profile of these Shc‐associating proteins, however, differed among the tumor cell lines. Our results indicate that Shc is a common downstream element of EGFR signaling in prostate tumor cells and suggest multiple functions for Shc in prostate tumorigenesis. Int. J. Cancer 77:923–927, 1998.© 1998 Wiley‐Liss, Inc.

No abstract

No abstract