Hemispheric asymmetry in ocean change and the productivity of ecosystem sentinels

Climate change and other human activities are causing profound effects on marine ecosystem productivity. We show that the breeding success of seabirds is tracking hemispheric differences in ocean warming and human impacts, with the strongest effects on fish-eating, surface-foraging species in the north. Hemispheric asymmetry suggests the need for ocean management at hemispheric scales. For the north, tactical, climate-based recovery plans for forage fish resources are needed to recover seabird breeding productivity. In the south, lower-magnitude change in seabird productivity presents opportunities for strategic management approaches such as large marine protected areas to sustain food webs and maintain predator productivity. Global monitoring of seabird productivity enables the detection of ecosystem change in remote regions and contributes to our understanding of marine climate impacts on ecosystems.

Abstract 1159: Circulating cell-free DNA (cfDNA) levels and fragmentation patterns discriminate muscle invasive from non-muscle invasive urothelial cancer of the bladder

Purpose: There is risk of clinical under-staging of muscle invasive bladder cancer (MIBC) by trans-urethral resection (TURBT) alone. Circulating biomarkers may improve the staging and pre-treatment risk stratification of patients with bladder cancer by discriminating non-muscle invasive (NMIBC) and MIBC.

Methods: Peripheral blood from 74pts with BC (30NMIBC, 15 MIBC and 29 Met BC was collected in Streck BCT tubes and processed to obtain cfDNA. Total cfDNA quantity (ng/mlof plasma) was assessed by fluorimetry. cfDNA fragment size was measured by Bioanalyzer DNA analysis. Wilcoxon rank sum test, Cochran-armitage trend test, Fisher's exact t-test were used to compare cfDNA quantity and fragmentation pattern (small fragments are indicative of circulating tumor DNA) among pts with NMIBC, MIBC, met BC to predict invasiveness of BC.

Results: There was no significant difference in cfDNA concentration between MIBC and met BC, however, cfDNA levels were significantly lower in pts with NMIBC vs MIBC and met BC. The difference was even more pronounced in case of cfDNA fragment (100-400bp) conc. Total cfDNA (ng/ml) was a good predictor in bladder cancer invasiveness, AUC 0.8 (95% CI 0.7-0.9). The risk of invasion was significantly lower inpatients with total cfDNA &lt 1.5 ng/ml and significantly higher in patients with cfDNA &gt 7.0ng/ml. In 18 pts with cfDNA&lt1.5ng/ml, only 1 pt (5.6%) had invasive cancer (at 1.2). The percent risk of invasive disease was 70.6% for cfDNA concentrations between 1.5-7.0ng/ml and 79.0% for cfDNA &gt 7.0. No invasion was observed among 13 pts with total cfDNA less than 1. This exploratory study suggests that cfDNA levels may correlate with BC stage and hence can be used in juxtaposition with TURBT, exam under anesthesia and CT to better predict clinical staging.

Conclusions: Circulating cfDNA may be a dynamic, low-cost and minimally invasive biomarker that can be used in conjunction with TURBT to predict tumor invasiveness, reduce under-staging, and risk stratify patients for appropriate curative intent therapy.

cfDNA variation with BC stagingcfDNA parametersTotalNMIBCMIBCMET BCp-value(N=74)(N=30)(N=15)(N=29)cfDNA_ng/ml of plasma7.3[2.9,12.5]1.3[0.48,7.4]9.7[4.0,13.3]8.7[6.1,14.4]<0.001bcfDNA fragment (100to400bp)_pg/ml of plasma76.9[0.00,5591.2]0.00[0.00,59.4]3322.7[0.00,8405.2]3344.7[53.8,21930.3]<0.001b

Citation Format: Shinjini Ganguly, Jaleh Fallah, Hong Li, Wei Wei, Aysegul Balyimez, Claudia Marcela Diaz, Pat Rayman, Marcelo Lamenza, Priscilla Dann, Donna Company, Rahul Tendulkar, Jacob Scott, Mohamed Abazeed, Jorge A. Garcia, Moshe C. Ornstein, Brian R. Rini, Byron Lee, Petros Grivas, Omar Mian. Circulating cell-free DNA (cfDNA) levels and fragmentation patterns discriminate muscle invasive from non-muscle invasive urothelial cancer of the bladder [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1159.

Association of cell-free DNA (cfDNA) levels with myeloid-derived suppressor cells (MDSC) levels in blood of patients (pts) with muscle invasive (MI) and metastatic (met) bladder cancer (BC)

4528

Background: cfDNA can be detected in healthy individuals but higher concentrations are present in pts with cancer. MDSC are immature immunosuppressive cells that can be mobilized from bone marrow by tumor-related factors. Higher blood MDSC levels have been associated with worse outcomes in pts with solid tumors including BC. We assessed correlations between cfDNA and MDSC levels in pts with MIBC and met BC. Methods: Peripheral blood from pts with MIBC and met BC was collected in Streck BCT tubes and processed to obtain cf nucleic acid extracts. Total cfDNA was determined by fluorimetry. Cell-free DNA fragment size was measured by Bioanalyzer DNA analysis; 100-400 bp fragments (mono- and di-nucleosomal fragments linked to granulocytic processing of apoptotic and necrotic tumor cells) were designated low molecular weight (LMW-frags). The % of MDSC (CD33+/HLADR-) and subtypes were measured. MDSC subtypes were defined as polymorphonuclear (PMN-MDSC: CD15+/CD14-), monocytic (M-MDSC: CD15-/CD14+) and uncommitted (UNC-MDSC: CD15-/CD14-). Spearman’s correlation test was used for analysis. Results: Blood from 37 pts (19% women, 40% never smokers) with MIBC or met BC was collected: 15 (41%) with MIBC and 22 (59%) with met BC at time of collection. There was a significantly positive correlation between total MDSC and cfDNA levels (r = 0.57, P = 0.0003). Among MDSC subtypes, there was a significantly positive correlation between PMN-MDSC and cfDNA levels (r = 0.61, P < 0.0001). The higher level of LMW-frags was significantly but moderately associated with higher total MDSC (r = 0.43, P 0.008) and PMN-MDSC (r = 0.41, P 0.01) levels. There was no significant correlation between cfDNA level and other MDSC subtypes. Conclusions: There was a positive correlation between total and PMN-MDSC with cfDNA levels in blood from pts with MIBC and met BC. That may suggest a putative role for MDSC in mediating cfDNA release into the circulation, consistent with prior reports of granulocyte-mediated ctDNA processing. Further studies need to identify mechanisms and implications of our findings and potential correlation with clinical outcomes.

Circulating cell-free DNA (cfDNA) levels and fragmentation pattern can distinguish nonmuscle invasive (NMI) from muscle-invasive (MI) and metastatic (met) bladder cancer (BC)

4523

Background: Occult MI and met BC may be under-staged. Circulating cfDNA may be a dynamic, low-cost and minimally invasive biomarker. We evaluated correlations between total circulating cfDNA and presence of MIBC and met BC. We hypothesized that the relative abundance of circulating low molecular weight cfDNA would correlate with BC stage. Methods: Peripheral blood from pts with BC was collected in Streck BCT tubes and processed to obtain cf nucleic acid extracts. Total cfDNA quantity (ng/ml) was assessed by fluorimetry. cfDNA fragment size was measured by Bioanalyzer DNA analysis. Wilcoxon rank sum test and Fisher’s Exact test were used to compare cfDNA quantity and fragmentation pattern among pts with NMIBC, MIBC, met BC. Results: Blood was obtained from 58 pts with BC (20% women, 34% never smokers, median age 71 (29-89). There was no significant difference in cfDNA between MIBC and met BC, however, it was significantly lower in pts with NMIBC vs MIBC and met BC (table). The concentration of low molecular weight fragments (LMW-frags) (100 - 400) base pairs and the ratio of LMW-Frag to cfDNA were significantly different between pts with NMIBC and pts with MIBC or met BC (table). Using median values as the cutoff, there was a significantly higher proportion of pts with cfDNA > 7 ng/ml and LMW-frags > 1.6 ng/mL, in MIBC & met BC vs NMIBC (p < 0.001). The % of pts with LMW-frags to cfDNA > 30%, was significantly different among NMIBC, MIBC and met BC groups: 16%, 53%, 78%, respectively (p < 0.001). Conclusions: This exploratory study suggests that cfDNA levels may correlate with BC stage. Measuring the relative abundance of LMW-frags with the expected size of cf DNA can enhance the specificity of cfDNA analysis for distinction between MIBC and met BC. Further studies are needed to confirm findings and define the optimal cut-points for optimal BC staging. [Table: see text]

Correlation of myeloid-derived suppressor cells (MDSC) with pathologic complete response (pCR), recurrence free survival (RFS), and overall survival (OS) in patients with urothelial carcinoma (UC) undergoing cystectomy

437

Background: MDSCs play an important role in maintaining a tumor immunosuppressive microenvironment. The association of circulating levels of MDSCs with pCR (pT0N0) and outcomes was investigated in patients (pts) with non-metastatic UC undergoing cystectomy. Methods: Peripheral blood samples from pts with non-metastatic UC was collected. MDSCs were measured in freshly purified peripheral blood mononuclear cells, using flow cytometry. Total (T) MDSC was defined as CD33+/HLADR-. T-MDSC subtypes were polymorphonuclear (PMN-MDSC: CD15+/CD14-), monocytic (M-MDSC: CD15-/CD14+], and uncommitted (UC-MDSC: CD15-/CD14-]. MDSC populations were presented as % of live nucleated blood cells. Wilcoxon rank sum test was used to compare MDSCs between pCR groups. Kaplan-Meier and log-rank test were used to analyze RFS and OS. Results: MDSC data were available for 124 pts (106 male, 18 female), median age 68, 28 (23%) never smokers, 93 (75%) pure UC. Thirty four pts (27%) received intravesical BCG; 49 (39%) received neoadjuvant chemotherapy (NAC); 22 (19%) had pCR (pT0N0) following surgery. PMN-MDSC was the dominant subtype (42%) and frequency of UC-MDSC and M-MDSC was 40% and 17%, respectively. Circulating levels of T-MDSC and PMN-MDSC were significantly lower in pCR patients than those in non-pCR patients (Table). Sixteen deaths were observed and 21 pts recurred after surgery. The median follow-up time of patients alive was 18.7 months (range 0.3-42.4). The median OS or RFS of all patients was not reached. One-year and two-year OS rates were 94% and 83%, respectively. One-year and two-year RFS rates were 82% and 69%, respectively. There was no association between MDSC subtypes with OS or RFS. Conclusions: Total- and PMN-MDSC subtypes in blood were significantly correlated with pCR in pts with non-metastatic UC who undergo cystectomy. The relatively short follow-up may impact the association with RFS and OS; additional follow-up is needed. [Table: see text]

Serial measurements of myeloid derived suppressor cells (MDSC) in metastatic urothelial carcinoma (mUC) patients (pts) treated with immune checkpoint inhibitors (CI)

e16005

Background: MDSC are a heterogeneous population of immunosuppressive cells with potentially predictive implications in UC pts receiving CI. We hypothesized that MDSC populations may change after CI exposure. Methods: Serial peripheral blood samples were collected from mUC pts treated with CI. MDSC were measured in fresh unfractionated whole blood (WB) and in peripheral blood mononuclear cells (PBMC). MDSC were identified by flow cytometry in WB and defined as LinloCD33+/HLADR- [(T)otal MDSC]. MDSC subsets were defined as (G)ranulocytic (CD15+CD14-), (M)onocytic (CD15-CD14+), (I)mmature (CD15-CD14-), or CD11b+. MDSC populations were presented as % of live nucleated blood cells and as absolute numbers from WB. The Wilcoxon signed rank and rank sum tests were used to assess changes in MDSC populations while on CI. Results: 17 pts treated with CI (9 atezolizumab [A], 8 pembrolizumab [P]) had ≥ 2 MDSC samples for analysis. Median age at diagnosis was 71 (46-81), 12 men, 29% never smokers; 53% / 29% / 18% ECOG PS 0/1/2 and 59% visceral metastasis at the time of 1st sample collection. 10 pts received CI as 1st line therapy (Tx) in metastatic setting; 7 pts received chemotherapy as 1st-line Tx for mUC (6 platinum-based, 1 docetaxel) and CI as 2nd-line Tx. In 16 pts with samples before 1stdose, there was a relative decrease (median 36.3%, range -59.7 to +21.2) in PBMC % I-MDSCs between 1st and 2nd samples (p=0.06). Interestingly, PBMC %M-MDSC and %I-MDSC tended to increase compared to baseline in pts treated with P, while they tended to decrease in pts treated with A (Table). Conclusions: In this cohort of pts with mUC treated with CIs,MDSC changes differed based on CI (anti-PDL1 or anti-PD1). Further study in larger cohort with various prior Tx lines and longer follow up as well as correlations with Tx response, toxicity and outcomes are ongoing. [Table: see text]

Myeloid derived suppressor cells (MDSC) and inflammatory biomarkers in metastatic urothelial carcinoma (mUC)

4548

Background: MDSC are potent immunosuppressive cells with prognostic implications in many solid tumors. We previously reported significant correlations between MDSC and clinicopathologic features in localized UC. We hypothesized that different MDSC populations may correlate with inflammatory biomarkers and clinicopathologic features in mUC. Methods: Peripheral blood samples were collected from 46 mUC pts. MDSCs were measured in fresh unfractionated whole blood (WB) and in peripheral blood mononuclear cells (PBMC). MDSCs were identified by flow cytometry in WB and defined as LinloCD33+/HLADR- [(T)otal MDSC]. MDSC subsets were defined as (G)ranulocytic (CD15+CD14-), (M)onocytic (CD15-CD14+), (I)mmature (CD15-CD14-), or CD11b+. MDSC populations were presented as % of live nucleated blood cells and as absolute numbers from WB. Spearman correlations (r) and Wilcoxon rank sum test were used to assess correlations between MDSC populations & clinicopathologic factors. Results: Of 46 pts:78% men, median age at diagnosis 69 (31-83), 33% never smokers, 76% pure UC, 76% bladder primary, 28% prior intravesical therapy, 35% prior neoadjuvant chemotherapy, 56% prior cystectomy, 83% overweight/obese. G-MDSC was the predominant subset in WB (43%) and PBMC (39%), although M-MDSC were almost equally predominant in PBMC (35%). There was a correlation between the WB and PBMC values of T-, I-, and M- MDSC (p≤0.05). Higher % WB I-MDSC correlated with lower blood neutrophil/lymphocyte ratio (NLR) (p = 0.009), while higher WB G-MDSC and %PBMC G-MDSC were associated with higher NLR (p = 0.03 and p = 0.02, respectively). Higher I-MDSC / G-MDSC ratio was associated with lower NLR (r = -0.35, p = .02) and with various clinicopathologic parameters. Conclusions: HigherI-MDSC / G-MDSC ratio correlates inversely with NLR, which is considered an inflammatory biomarker and had prognostic value in other studies. The mechanism of MDSC interaction with inflammatory response in mUC pts merits evaluation and is being investigated in a larger cohort of UC pts on chemotherapy or immunotherapy (with longer follow up).

Assessment of blood and tissue myeloid derived suppressor cells (MDSC), clinicopathologic factors, and treatment response in urothelial carcinoma (UC) patients (pts) undergoing surgery

362

Background: MDSC are heterogeneous immunosuppressive cells with potential predictive/prognostic role in cancer. The association between MDSC, clinicopathologic factors and pathologic response in pts with UC merits evaluation. Methods: Peripheral blood and/or tissue was collected from 120 pts. MDSC were measured in fresh unfractionated whole blood (WB), in peripheral blood mononuclear cells (PBMC) and fresh tumor tissue. MDSCs were identified by flow cytometry in WB and defined as LinloCD33+/HLADR- ((T)otal MDSC). MDSC subsets were defined as LinloCD33+/HLADR- and (G)ranulocytic (CD15+CD14-), (M)onocytic (CD15-CD14+), (I)mmature (CD15-CD14-, CD11b+ ). MDSC populations were presented as % of live nucleated blood cells and as absolute numbers from WB. Spearman correlations (r) and Wilcoxon rank sum test were used to assess correlations between MDSC populations, clinicopathologic factors and pT0N0%. Results: Of 120 pts, 82 were non-metastatic: 58 had only blood, 23 had blood & tissue, 1 had only tissue available for analysis. Of these 82 non-metastatic pts, 70 were men, median age 68; 81 pts had primary UC histology, 1 small cell cancer, 24 had mixed UC histology; 24 had prior intravesical therapy, 34 had neoadjuvant therapy (79% cisplatin-based, 21% unknown), 4 pts had post-op recurrence. At cystectomy: 15/82 pT0, 22/82 pT3/4; 37/82 CIS; 8/78 pN+. Significant associations were seen between MDSC blood levels and mixed histology, CIS, pN+, and lower pT0N0% (Table). Tumor M-MDSCs were associated with pN+ (p=0.05). There was significant correlation between tumor and WB % M-MDSC (r=0.55, p=0.007), and tumor and WB % G-MDSC (r=0.46, p=0.03). Conclusions: Blood MDSC levels correlate with several clinicopathologic factors and may predict pathological complete response (pT0N0). Assessment of association between MDSC levels, outcome and immunotherapy response is ongoing including in metastatic pts. [Table: see text]

Effects of ambient air temperature, humidity and rainfall on annual survival of adult little penguins Eudyptula minor in southeastern Australia

Seabirds are subject to the influences of local climate variables during periods of land-based activities such as breeding and, for some species, moult; particularly if they undergo a catastrophic moult (complete simultaneous moult) as do penguins. We investigated potential relationships between adult penguin survival and land-based climate variables (ambient air temperature, humidity and rainfall) using 46 years of mark-recapture data of little penguins Eudyptula minor gathered at a breeding colony on Phillip Island in southeastern Australia. Our results showed that adult penguin survival had a stronger association with land-based climate variables during the moult period, when birds were unable to go to sea for up to 3 weeks, than during the breeding period, when birds could sacrifice breeding success in favour of survival. Annual adult survival probability was positively associated with humidity during moult and negatively associated with rainfall during moult. Prolonged heat during breeding and moult had a negative association with annual adult survival. Local climate projections suggest increasing days of high temperatures, fewer days of rainfall which will result in more droughts (and by implication, lower humidity) and more extreme rainfall events. All of these predicted climate changes are expected to have a negative impact on adult penguin survival.

Characteristics of marine debris that entangle Australian fur seals (Arctocephalus pusillus doriferus) in southern Australia

Marine debris is a global issue that can have devastating impacts on marine mammals. To understand the types of materials that result in entanglement and thus the potential impact of entangling items on marine wildlife, we analysed data collected from items in which Australian fur seals had been entangled in southern Victoria, Australia over a 15year period. From 1997 to 2012, 138 entangling items were removed from seals. The majority of these entanglements were plastic twine or rope, and seals were entangled in green items more than in any other colour. In general, younger seals were more likely to be entangled than adults. Understanding the effects of marine debris entanglement on the Australian fur seal population can lead to more effective management of the sources of debris and the wildlife that interact with it.

Development of a chronic kidney disease patient navigator program

BACKGROUND

Chronic Kidney Disease (CKD) is a public health problem and there is a scarcity of type 2 CKD translational research that incorporates educational tools. Patient navigators have been shown to be effective at reducing disparities and improving outcomes in the oncology field. We describe the creation of a CKD Patient Navigator program designed to help coordinate care, address system-barriers, and educate/motivate patients.

METHODS

The conceptual framework for the CKD Patient Navigator Program is rooted in the Chronic Care Model that has a main goal of high-quality chronic disease management. Our established multidisciplinary CKD research team enlisted new members from information technology and data management to help create the program. It encompassed three phases: hiring, training, and implementation. For hiring, we wanted a non-medical or lay person with a college degree that possessed strong interpersonal skills and experience in a service-orientated field. For training, there were three key areas: general patient navigator training, CKD education, and electronic health record (EHR) training. For implementation, we defined barriers of care and created EHR templates for which pertinent study data could be extracted.

RESULTS

We have hired two CKD patient navigators who will be responsible for navigating CKD patients enrolled in a clinical trial. They have undergone training in general patient navigation, specific CKD education through directed readings and clinical shadowing, as well as EHR and other patient related privacy and research training.

CONCLUSIONS

The need for novel approaches like our CKD patient navigator program designed to impact CKD care is vital and should utilize team-based care and health information technology given the changing landscape of our health systems.

A comparison of the diets of feral cats Felis catus and red foxes Vulpes vulpes on Phillip Island, Victoria

THE introduction of feral cats (Felis catus) and red foxes (Vulpes vulpes) to Australia in the 1800s had a profound impact on resident ecosystems. Both predators colonised successfully and now are distributed across most of mainland Australia (Saunders et al. 1995; Abbott 2002). They consume mainly ground-dwelling mammals (Coman 1973; Croft and Hone 1978; Jones and Coman 1981; Lapidge and Henshall 2002; Hutchings 2003), but where these are scarce, birds, reptiles, insects and human refuse may become important dietary components (e.g., Bubela et al. 1998; Paltridge 2002). Although they prey on similar species, when compared at the same location differences in diet between the predators are evident (Triggs et al. 1984; Catling 1988; Risbey et al. 1999).

[Sensitivity and significance of nuclear magnetic tomography findings of finger joints in rheumatoid arthritis]

Evaluation of the sensitivity and value of magnetic resonance imaging (MRI) findings and miniarthroscopic investigations (mini-/needle-arthroscopy = MA) of metacarpophalangeal (MCP) joints in patients with rheumatoid arthritis (RA). 30 patients with RA (21 female, 9 male), disease duration 2 months to 22 years and mean disease activity score (DAS) of 3.90 (range: 2.00-7.67) were examined by MRI of the hand (MCP region) and following MA of the MCP-II joints. MRI parameters for arthritis (synovial enhancement, synovial extension, cortical alterations, joint gap width) and corresponding macroscopic items (synovial extension, synovial hyperemia and vascularity, cortical alterations) by MA, scored semiquantitatively for synovitis (graduated from 0-III degree), were correlated. Additionally, normal radiographs of the hands were performed and compared with MRI findings concerning the detection of bony lesions. Evaluation of the 30 MRI and MA examination revealed highly significant correlations (p < 0.0001) for the parameters of synovial extension (MRI/MA), cortical alterations (MRI/MA) and synovial enhancement (MRI) compared to synovial hyperemia and vascularity (MA). We found significant correlations for parameters of activity and chronicity of RA pathology as assessed by MRI and MA. The detection rate of cortical lesions by MRI was two and a half times higher than by X-ray. MRI findings of MCP-II joints compared to those of MCP III-V showed that the MCP-II joint was more strongly involved.

[Synovial membrane diagnostic assessment in rheumatoid arthritis]

Rheumatoid arthritis (RA) is the most frequent inflammatory rheumatic disease. At the beginning of the disease, where, based on today's knowledge the therapeutic possibilities are largest, the diagnostic methods do not permit a differentiated estimation of the prognosis. Conventional x-rays are mostly normal and serum markers unspecific. So far--in contrast to other diseases--only little information had been drawn from the pathomorphologic substrate "synovialis" itself to assess the prognosis. Reasons therefor were found in difficulties in obtaining synovial tissue besides surgical interventions, particularly in patients with early arthritis. By minimalizing the diagnostic instruments and improvement of the technique, synovial tissue sampling in RA has become minimally invasive and it is even possible to perform on the smallest joints, such as finger joints. Hereby, synovial analysis is open for detecting pathways of inflammation and joint destruction, which might support the advancement of new therapeutic strategies, followed by a better prognosis and outcome of RA.

Satellite Tracker Deployments On Adult, Male Australian Fur Seals (Arctophalus Pusillus Doriferus): Methods And Preliminary Results

In May 1999, four adult male, Australian fur seals (Arctocephalus pusillus doriferus) from the Seal Rocks colony, Victoria, were fitted with satellite transmitters that provided locations for between 2 and 7 months. Foraging trips during winter and early spring averaged 7.4 days (range for all trips 0.9 to 24.6) and between-trip rests lasted 2.8 days (range 0.3 to 5.7). Between-trip rest sites included Seal Rocks, other colonies and other haul-out sites. The seals foraged mostly in western Bass Strait and in water depths < 100 m.

Temporally regulated overexpression of parathyroid hormone-related protein in the mammary gland reveals distinct fetal and pubertal phenotypes

We have previously demonstrated that overexpression of parathyroid hormone-related protein (PTHrP) in the mammary glands of transgenic mice results in defects in ductal elongation and branching during puberty and in lobuloalveolar development during pregnancy. In addition, we have shown that PTHrP is necessary for the formation of the initial ductal tree during embryonic mammary development. In order to examine the effect of varying the timing of PTHrP overexpression on mammary development, we created tetracycline-regulated, K14-tTA/Tet(O)-PTHrP double transgenic mice. In this report, we document that this 'tet-off' system directs transgene expression to the mammary gland and that it is fully repressed in the presence of tetracycline. Using these mice, we demonstrate that transient overexpression of PTHrP before birth causes defects in ductal branching during puberty and that overexpression of PTHrP during puberty decreases the rate of ductal elongation. Furthermore, we demonstrate that if PTHrP overexpression is initiated after ductal morphogenesis is completed, lobuloalveolar development is unaffected. Finally, we demonstrate that the impairment in ductal elongation caused by PTHrP is associated with an increase in the basal rate of epithelial cell apoptosis in terminal end buds and a failure to increase end bud cell proliferation and decrease apoptosis in response to estrogen and progesterone.

Magnetic resonance imaging and miniarthroscopy of metacarpophalangeal joints: sensitive detection of morphologic changes in rheumatoid arthritis

OBJECTIVE

To evaluate and characterize magnetic resonance imaging (MRI) findings in the metacarpophalangeal (MCP) joints of rheumatoid arthritis (RA) patients macroscopically, using miniarthroscopy (MA; needle arthroscopy).

METHODS

The second MCP joint of the dominant hand of 22 RA patients (13 with various RA activities/stages; 9 with early RA [< or = 1.5 years' duration]) was examined by MRI followed by MA. Findings were evaluated by standardized semiquantitative measures of synovial and bony pathologic changes of the MCP joint, and were compared with the clinical and conventional radiologic findings.

RESULTS

Erosions and pre-erosions were detected in 17 of 22 patients by MRI; 2 of the other 5 patients (all early RA) displayed bony changes on MA. All 10 joints with pre-erosions on MRI (grade I bony alterations on MRI) exhibited significant cartilaginous and bony pathology on MA. Synovial membrane pathology was detected in all but 1 patient by MRI and in all patients by MA, although findings of plain radiography were normal in 6 of the 22 patients and another 9 patients had a Larsen score of 1. Semiquantitative analysis of synovial findings of MRI revealed gadolinium diethylenetriaminepentaacetic acid enhancement as a significant marker of macroscopically varied synovial vascularity and hyperemia, both of which strongly correlated with clinical activity (as measured by the Disease Activity Score). The extent of synovitis/synovial proliferation shown by MA and MRI were significantly correlated with each other, but not with any other activity or damage parameter analyzed.

CONCLUSION

In RA, both MRI and MA findings support early detection and staging of synovial changes. Ongoing longitudinal studies are aimed at evaluating the value of synovial proliferation as visualized by both methods.

[MR-morphological changes of the metacarpophalangeal joints in patients with rheumatoid arthritis: Comparison of early and chronical stages]

MR-morphological changes of the metacarpophalangeal joints in patients with rheumatoid arthritis: Comparison of early and chronical stages.

PURPOSE

Evaluation of MRI findings in the metacarpophalangeal (MCP) joints in patients with early (eRA) and chronical rheumatoid arthritis (cRA).

MATERIAL AND METHODS

In 22 RA patients (9 with disease duration </= 1.5 years = eRA) the dominant hands were examined by MRI in coronal T(2) weighted turbo-spin-echo (TSE). T(1) weighted spin-echo (SE) sequences before and after injection of Gd-DTPA and fat-suppressed short tau inversion recovery (STIR) sequences, followed by miniarthroscopy (MA) of the MCP II joint after an interval of 24 hours. MRI and MA findings were assessed using standardised semiquantitative items of synovial and bony pathologies and a statistical comparison between eRA and cRA patients was performed.

RESULTS

In MRI synovial proliferation was detected in 13/13 cRA and 8/9 eRA patients. It was statistically not significant; the degree of synovial proliferation was however lower in the eRA group. All eRA patients with synovial changes showed enhancement after administration of contrast medium, a marker which correlated with the clinical activity. In 2/13 cRA patients no uptake of contrast medium was evident. Bony erosions and strongly narrowing joint space correlated with disease duration and were documented significantly rarer in the eRA patients (1/9, 2/9) than in the cRA patients (9/13, 10/13).

CONCLUSION

In RA patients, MRI of the metacarpophalangeal joints can detect specific pathological changes which are observed significantly more often in either early or chronic stages and which are associated with disease activity and duration.

Absence of functional type 1 parathyroid hormone (PTH)/PTH-related protein receptors in humans is associated with abnormal breast development and tooth impaction

Recent studies in transgenic mice have demonstrated that PTH-related protein (PTHrP), signaling through the type 1 PTH/PTHrP receptor (PTHR1), regulates endochondral bone development and epithelial-mesenchymal interactions during the formation of the mammary glands and teeth. Recently, it has been shown that loss-of-function mutations in the PTHR1 gene result in a rare, lethal form of dwarfism known as Blomstrand chondrodysplasia. These patients suffer from severe defects in endochondral bone formation, but abnormalities in breast and tooth development have not been reported. To ascertain whether PTHrP signaling was important to human breast and tooth development, we studied two fetuses with Blomstrand chondrodysplasia. These fetuses lack nipples and breasts. Developing teeth were present, but they were severely impacted within the surrounding alveolar bone, leading to distortions in their architecture and orientation. Compatible with the involvement of PTHR1 and PTHrP in human breast and tooth morphogenesis, both were expressed within the developing breasts and teeth of normal human fetuses. Therefore, impairment of the PTHrP/PTHR1 signaling pathway in humans is associated with severe abnormalities in tooth and breast development. In addition to regulating human bone formation, this signaling pathway is also necessary for the normal development of the human breast and tooth.

Parathyroid hormone-related protein maintains mammary epithelial fate and triggers nipple skin differentiation during embryonic breast development

Prior reports have demonstrated that both parathyroid hormone-related protein (PTHrP) and the type I PTH/PTHrP receptor are necessary for the proper development of the embryonic mammary gland in mice. Using a combination of loss-of-function and gain-of-function models, we now report that PTHrP regulates a series of cell fate decisions that are central to the survival and morphogenesis of the mammary epithelium and the formation of the nipple. PTHrP is made in the epithelial cells of the mammary bud and, during embryonic mammary development, it interacts with the surrounding mesenchymal cells to induce the formation of the dense mammary mesenchyme. In response, these mammary-specific mesenchymal cells support the maintenance of mammary epithelial cell fate, trigger epithelial morphogenesis and induce the overlying epidermis to form the nipple. In the absence of PTHrP signaling, the mammary epithelial cells revert to an epidermal fate, no mammary ducts are formed and the nipple does not form. In the presence of diffuse epidermal PTHrP signaling, the ventral dermis is transformed into mammary mesenchyme and the entire ventral epidermis becomes nipple skin. These alterations in cell fate require that PTHrP be expressed during development and they require the presence of the PTH/PTHrP receptor. Finally, PTHrP signaling regulates the epidermal and mesenchymal expression of LEF1 and (β)-catenin, suggesting that these changes in cell fate involve an interaction between the PTHrP and Wnt signaling pathways.

Targeted expression of placental lactogen in the beta cells of transgenic mice results in beta cell proliferation, islet mass augmentation, and hypoglycemia

The factors that regulate pancreatic beta cell proliferation are not well defined. In order to explore the role of murine placental lactogen (PL)-I (mPL-I) in islet mass regulation in vivo, we developed transgenic mice in which mPL-I is targeted to the beta cell using the rat insulin II promoter. Rat insulin II-mPL-I mice displayed both fasting and postprandial hypoglycemia (71 and 105 mg/dl, respectively) as compared with normal mice (92 and 129 mg/dl; p < 0.00005 for both). Plasma insulin concentrations were inappropriately elevated, and insulin content in the pancreas was increased 2-fold. Glucose-stimulated insulin secretion by perifused islets was indistinguishable from controls at 7.5, 15, and 20 mm glucose. Beta cell proliferation rates were twice normal (p = 0. 0005). This hyperplasia, together with a 20% increase in beta cell size, resulted in a 2-fold increase in islet mass (p = 0.0005) and a 1.45-fold increase in islet number (p = 0.0012). In mice, murine PL-I is a potent islet mitogen, is capable of increasing islet mass, and is associated with hypoglycemia over the long term. It can be targeted to the beta cell using standard gene targeting techniques. Potential exists for beta cell engineering using this strategy.

Effects of the seasonal availability of short-tailed shearwaters (Puffinus tenuirostris) on the diet of red foxes (Vulpes vulpes) on Phillip Island, Victoria

The diet of red foxes (Vulpes vulpes) on Phillip Island, Victoria, was assessed from the frequency of occurrence and volume of food items in stomachs of foxes killed during a 16-year control program (1983 to 1998). Of the 289 stomachs examined, 244 (85%) contained recognisable food items. Based on frequency of occurrence, the most common prey were short­tailed shearwaters (Puffinus tenuirostris, 47%), European rabbits (Oryctolagus cuniculus, 30%), house mice (Mus musculus, 15%), insects (15%), little penguins (Eudyptula minor, 12%), other birds (12%), sheep (Ovis aries 8%) and black rats (Rattus rattus 5%). The seasonal attendance patterns of P. tenuirostris caused substantial variations in the fox diet. When P. tenuirostris were present, between September and April each year, they were the most common food item, and when absent, they were replaced by rabbits. The sex of foxes did not appear to influence diet, but age did. Juvenile (Rubus fructicosus), than did adult foxes.

Miniarthroscopy of metacarpophalangeal joints in rheumatoid arthritis. Rating of diagnostic value in synovitis staging and efficiency of synovial biopsy

OBJECTIVE

To evaluate miniarthroscopy (MA) (needle arthroscopy) of involved joints in rheumatoid arthritis (RA) in the early detection and staging of synovitis and its application in visual guided synovial biopsies.

METHODS

1.0 and 1.9 mm (0 degree/30 degrees) arthroscopes were used in a 2 portal technique. MA performance was developed and evaluated first on hand cadavers (n = 20) and then transferred to metacarpophalangeal (MCP) joints under local anesthesia conditions. Joints of 20 patients with RA with different disease activity and duration were scoped and rated according to scores adapted from arthroscopy of other joints.

RESULTS

In 20/20 cases MA provided visualizing and magnification of intraarticular features of MCP joints in RA and allowed grading of synovial alterations, chondromalacia, and bony alterations. Synovial surface changes, thickness, and fibrosis were related to disease duration, as was damage to cartilage and bone. The degree of acute inflammatory reactions like vascularity and hyperemia varied independently of chronic changes; synovial proliferation was reflected to some extent by C-reactive protein. In 2 patients with early RA, synovitis criteria were found macroscopically and histologically. In 18/20 joints, biopsies were taken under visual control; in the other 2, progression of disease (Larsen score >3) limited arthroscopy to 1.0 scope imaging only. Sampling sizes were sufficient for histologic and molecular analysis.

CONCLUSION

The developed standardized procedure of MCP arthroscopy is minimally invasive, practicable, and well tolerated by patients, and may allow synovitis monitoring, staging, and biopsy in patients with early as well as chronic arthritis.

Immunohistochemical detection of parathyroid hormone-related protein in a cutaneous squamous cell carcinoma causing humoral hypercalcemia of malignancy

Humoral hypercalcemia of malignancy is a cancer-related hypercalcemia caused by production of humoral factors by malignant cells in patients without bone metastases. Squamous cell carcinomas are the tumors most frequently associated with humoral hypercalcemia of malignancy, and parathyroid hormone-related protein is the main humoral factor implicated. In spite of the fact that normal keratinocytes produce parathyroid hormone-related protein, it is highly unusual for patients with squamous cell carcinomas of the skin to present with humoral hypercalcemia of malignancy. We present a well-documented case of cutaneous squamous cell carcinoma complicated by hypercalcemia in a patient with high levels of plasma parathyroid hormone-related protein and immunohistochemical evidence of high parathyroid hormone-related protein production by the tumoral cells.

Lesions in many different spindle components activate the spindle checkpoint in the budding yeast Saccharomyces cerevisiae

The spindle checkpoint arrests cells in mitosis in response to defects in the assembly of the mitotic spindle or errors in chromosome alignment. We determined which spindle defects the checkpoint can detect by examining the interaction of mutations that compromise the checkpoint (mad1, mad2, and mad3) with those that damage various structural components of the spindle. Defects in microtubule polymerization, spindle pole body duplication, microtubule motors, and kinetochore components all activate the MAD-dependent checkpoint. In contrast, the cell cycle arrest caused by mutations that induce DNA damage (cdc13), inactivate the cyclin proteolysis machinery (cdc16 and cdc23), or arrest cells in anaphase (cdc15) is independent of the spindle checkpoint.

Expression and role of parathyroid hormone-related protein in human renal proximal tubule cells during recovery from ATP depletion

Parathyroid hormone (PTH)-related protein (PTHrP) is widely expressed in normal fetal and adult tissues and regulates growth and differentiation in a number of organ systems. Although various renal cell types produce PTHrP, and PTHrP expression in rat proximal renal tubules is upregulated in response to ischemic injury in vivo, the role of PTHrP in the kidney is unknown. To study the effects of injury on PTHrP expression and its consequences in more detail, the immortalized human proximal tubule cell line HK-2 was used in an in vitro model of ATP depletion to mimic in vivo renal ischemic injury. These cells secrete PTHrP into conditioned medium and express the type I PTH/PTHrP receptor. Treatment of confluent HK-2 cells for 2 h with substrate-free, glucose-free medium containing the mitochondrial inhibitor antimycin A (1 microM) resulted in 75% depletion of cellular ATP. After an additional 2 h in glucose-containing medium, cellular ATP levels recovered to approximately 75% of baseline levels. PTHrP mRNA levels, as measured in RNase protection assays, peaked at 2 h into the recovery period (at four times baseline expression). The increase in PTHrP mRNA expression was correlated with an increase in PTHrP protein content in HK-2 cells at 2 to 6 h into the recovery period. Heat shock protein-70 mRNA expression was not detectable under baseline conditions but likewise peaked at 2 h into the recovery period. Treatment of HK-2 cells during the recovery period after injury with an anti-PTHrP(1-36) antibody (at a dilution of 1:250) resulted in significant reductions in cell number and uptake of [3H]thymidine, compared with nonimmune serum at the same titer. Similar results were observed in uninjured HK-2 cells. It is concluded that this in vitro model of ATP depletion in a human proximal tubule cell line reproduces the pattern of gene expression previously observed in vivo in rat kidney after ischemic injury and that PTHrP plays a mitogenic role in the proliferative response after energy depletion.

Seasonal and annual foraging movements of little penguins from Phillip Island, Victoria

Little penguins, Eudyptula minor, from a breeding colony on Phillip Island, Victoria were radio-tracked at sea during incubation, chick-rearing and non-breeding periods from 1991 to 1993. Their locations, which we have assumed to reflect foraging movements, varied according to season and breeding activities, and there were marked differences from year to year. Duration and distance of trips ranged from single day-trips a few kilometres from Phillip Island, typically during the breeding season, to longer trips outside the breeding season up to 500 km away lasting more than a month, but 95% of all birds located were within 20 km of the coast. In the breeding season foraging trips averaged 4.4 days during incubation compared with 2.1 days when there were chicks in the nest; in the non-breeding period foraging trips took 5.2 days on average. The duration of trips for adults feeding chicks increased with the age of the chicks. Birds from nests on the north and south sides of Phillip Island differed in their use of areas close to the island, but showed a similar distribution on more distant trips. The location of foraging trips is discussed in relation to information on the abundance of prey species of fish within the foraging range of the birds.

Parathyroid hormone-related protein in the pancreatic islet and the cardiovascular system

Parathyroid hormone-related protein was discovered as the causative agent responsible for the common paraneoplastic syndrome, humoral hypercalcemia of malignancy. It is now clear that the PTHrP gene is expressed in virtually every cell and tissue in the body at some point in development or adult life and that the peptide is critical for normal life. Two of the tissues that produce PTHrP are the insulin-producing beta cells of the pancreatic islet and the vascular smooth muscle cells of the arterial wall. In this review, the physiologic roles of PTHrP in the islet and in the arterial wall are explored. PTHrP is a classical neuroendocrine prohormone that undergoes extensive post-translational processing to yield a family of daughter peptides that are the mature secretory forms of the peptide. In addition to its ability to act as a traditional endocrine, paracrine, or autocrine factor, PTHrP appears to be able to act as an "intracrine" factor as well, directly entering the nucleus after translation and stimulating proliferation, apoptosis, and perhaps other cellular responses as well. The cell biology underlying this phenomenon is also explored herein.

Progressive pancreatic islet hyperplasia in the islet-targeted, parathyroid hormone-related protein-overexpressing mouse

PTH-related protein (PTHrP) is a paracrine/autocrine factor produced in most cell types in the body. Its functions include the regulation of cell cycle, of differentiation, of apoptosis, and of developmental events. One of the cells which produces PTHrP is the pancreatic beta cell. We have previously described a transgenic mouse model of targeted overexpression of PTHrP in the beta cell, the RIP-PTHrP mouse. These studies showed that PTHrP overexpression markedly increased islet mass and insulin secretion and resulted in hypoglycemia. Those studies were limited to RIP-PTHrP mice of 8-12 weeks of age. In the current report, we demonstrate that PTHrP overexpression induces a progressive increase in islet mass over the life of the RIP-PTHrP mouse, and that, in contrast to some other models of targeted PTHrP overexpression, the phenotype is not developmental, but occurs postnatally. The marked increase in islet mass is not associated with a measurable increase in beta cell replication rates. A further slowing in the normally low islet apoptosis rate could not be demonstrated in the RIP-PTHrP islet. Thus, the marked increase in islet mass in the RIP-PTHrP mouse is unexplained in mechanistic terms. Finally, RIP-PTHrP mice are resistant to the diabetogenic effects of streptozotocin. The mechanisms responsible for the increase in islet mass in the RIP-PTHrP mouse likely lie in either very subtle changes in islet turnover or in early steps in islet differentiation and development. The ability of PTHrP to increase islet mass and function, as well as its ability to attenuate the diabetogenic effects of streptozotocin, indicate that further study of PTHrP on islet development and function are important and may lead to therapeutic strategies in diabetes mellitus.

Opposing mitogenic and anti-mitogenic actions of parathyroid hormone-related protein in vascular smooth muscle cells: a critical role for nuclear targeting

Parathyroid hormone-related protein (PTHrP) is a prohormone that is posttranslationally processed to a family of mature secretory forms, each of which has its own cognate receptor(s) on the cell surface that mediate the actions of PTHrP. In addition to being secreted via the classical secretory pathway and interacting with cell surface receptors in a paracrine/autocrine fashion, PTHrP appears to be able to enter the nucleus directly following translation and influence cellular events in an "intracrine" fashion. In this report, we demonstrate that PTHrP can be targeted to the nucleus in vascular smooth muscle cells, that this nuclear targeting is associated with a striking increase in mitogenesis, that this nuclear effect on proliferation is the diametric opposite of the effects of PTHrP resulting from interaction with cell surface receptors on vascular smooth muscle cells, and that the regions of the PTHrP sequence responsible for this nuclear targeting represent a classical bipartite nuclear localization signal. This report describes the activation of the cell cycle in association with nuclear localization of PTHrP in any cell type. These findings have important implications for the normal physiology of PTHrP in the many tissues which produce it, and suggest that gene delivery of PTHrP or modified variants may be useful in the management of atherosclerotic vascular disease.

Overexpression of parathyroid hormone-related protein in the pancreatic islets of transgenic mice causes islet hyperplasia, hyperinsulinemia, and hypoglycemia

Parathyroid hormone-related protein (PTHrP) is produced by the pancreatic islet. It also has receptors on islet cells, suggesting that it may serve a paracrine or autocrine role within the islet. We have developed transgenic mice, which overexpress PTHrP in the islet through the use of the rat insulin II promoter (RIP). Glucose homeostasis in these mice is markedly abnormal; RIP-PTHrP mice are hypoglycemic in the postprandial and fasting states and display inappropriate hyperinsulinemia. At the end of a 24-hour fast, blood glucose values are 49 mg/dl in RIP-PTHrP mice, as compared to 77 mg/dl in normal littermates; insulin concentrations at this time are 6.3 and 3.9 ng/ml, respectively. Islet perifusion studies failed to demonstrate abnormalities in insulin secretion. In contrast, quantitative islet histomorphometry demonstrates that the total islet number and total islet mass are 2-fold higher in RIP-PTHrP mice than in their normal littermates. PTHrP very likely plays a normal physiologic role within the pancreatic islet. This role is most likely paracrine or autocrine. PTHrP appears to regulate insulin secretion either directly or indirectly, through developmental or growth effects on islet mass. PTHrP may have a role as an agent that enhances islet mass and/or enhances insulin secretion.

A high abundance midregion species of parathyroid hormone-related protein: immunological and chromatographic characterization in plasma

The widespread expression of the gene for PTH-related protein (PTHrP) and the high interspecies conservation of the primary sequence of even the non-PTH-like portion of the protein argue for a vital role(s) for PTHrP in normal physiology. Emerging evidence suggests that PTHrP may be processed into smaller bioactive peptides, but the circulating forms of PTHrP are not well characterized. We have measured plasma concentrations in well defined patient groups using a RIA directed toward midregion PTHrP-(37-74), compared midregion concentrations to amino-terminal and carboxy-terminal PTHrP concentrations in the same patients, and further defined the components of midregion PTHrP immunoreactivity by high pressure liquid chromatography. Patients with humoral hypercalcemia of malignancy (HHM) had concentrations of PTHrP-(37-74) immunoreactivity of 90 +/- 10 pmol/L (mean +/- SEM), 9-fold higher than PTHrP-(1-74) immunoreactivity and about 3-fold higher than PTHrP-(109-138) immunoactivity. There was no consistent elevation of midregion PTHrP in patients with local osteolytic hypercalcemia, hyperparathyroidism, or renal failure, but discrimination of these groups from HHM was less complete using PTHrP-(37-74) than using PTHrP-(1-74) immunoactivity. By reverse phase high pressure liquid chromatography, plasma PTHrP-(37-74) immunoactivity in patients with HHM was resolved into three components: 1) a major peak coeluting with that found in medium conditioned by cells transfected with human PTHrP-(1-141), which we have previously sequenced and found to represent a midregion peptide beginning at residue 38; 2) a minor peak with both PTHrP-(37-74) and -(1-74) immunoreactivity; and 3) another minor peak with PTHrP-(37-74), but not PTHrP-(1-74), immunoactivity. In conclusion, the predominant circulating form of PTHrP in patients with HHM is a midregion species similar or identical to the peptide beginning at residue 38, which has been shown to be a secretory form of PTHrP.

Accumulation of carboxy-terminal fragments of parathyroid hormone-related protein in renal failure

We have recently demonstrated elevations of separate amino- and carboxy-terminal parathyroid hormone-related protein (PTHrP) fragments in patients with humoral hypercalcemia of malignancy (HHM) using both a two-site immunoradiometric assay (IRMA) with amino-terminal specificity for PTHrP, and with a carboxy-terminal radioimmunoassay (RIA) for PTHrP(109-138). PTHrP(109-138) immunoactivity from plasma of patients with HHM could not be extracted using an amino-terminal PTHrP immunoaffinity column, indicating that the carboxy-terminal region circulates as a discrete peptide. Carboxy-terminal immunoreactive (i) PTHrP levels were also elevated in normocalcemic patients with chronic renal failure (without cancer), whereas amino-terminal iPTHrP levels were normal in patients with renal failure. In order to further define the renal handling of carboxy-terminal PTHrP peptides, we have evaluated circulating iPTHrP(109-138) concentrations in patients with a wide range of renal function. We studied 25 patients with abnormal renal function of diverse etiologies whose creatinine clearances ranged from 66 ml/min to less than 5 ml/min. All patients had undetectable or low (< or = 2 pmol/liter) concentrations of iPTHrP(1-74). iPTHrP(109-138) concentrations were undetectable in patients with creatinine clearances > or = 20 ml/min, but became elevated in patients with creatinine clearances < 20 ml/min. The log of iPTHrP(109-138) correlated negatively with the log of creatinine clearance (r = 0.88, P = 0.0001). Mean iPTHrP(109-138) levels were slightly higher for patients on hemodialysis (32.7 +/- 3.1 pM) than for those on chronic ambulatory peritoneal dialysis (22.1 +/- 3.4 pM; P < 0.05), suggesting that some carboxy-terminal PTHrP fragments may be cleared to a greater extent by the peritoneal membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of vasoactive agents on induction of Egr-1 in rat mesangial cells: correlation with mitogenicity

The early growth response gene 1 (Egr-1) is a member of the family of immediate early response genes. Egr-1 encodes a nuclear phosphoprotein that binds a specific nonameric DNA sequence through three zinc-finger domains and functions as a transcriptional activator. We tested whether the vasoactive agents platelet-derived growth factor (PDGF), arginine vasopressin (AVP), serotonin (5-HT), and angiotensin II (ANG II) induced Egr-1 mRNA in cultured rat mesangial cells (MCs) and investigated the role of protein kinase C (PKC) in mediating the induction process. PDGF, AVP, and 5-HT induced Egr-1 mRNA within 15 min, reaching peak levels at 45-60 min. After PDGF and 5-HT stimulation, Egr-1 mRNA levels returned to baseline within 4 h, whereas AVP induced a sustained increase for up to 8 h. There was a very close correlation between doses required for Egr-1 induction and induction of MC proliferation. ANG II was a very weak MC mitogen and induced only a small increase in Egr-1 mRNA. Comparison of control cells with cells depleted of PKC by 48 h of PMA treatment revealed that induction of Egr-1 by PDGF and 5-HT is independent of PKC. In contrast, however, the Egr-1 response to AVP was diminished in PKC-depleted cells. AVP induced Egr-1 mRNA 10.9-fold in control cells, compared with 7.8-fold in PKC-depleted cells. Egr-1 mRNA after AVP stimulation remained elevated in control cells for up to 8 h but returned to baseline after 120 min in PKC-depleted cells. Similar results were obtained using the PKC-inhibitor H-7. Using immunocytochemistry, PDGF and AVP were found to induce Egr-1 protein within 30 min localized to the nucleus. We conclude that there is a strong correlation between induction of Egr-1 after stimulation with PDGF, AVP, 5-HT, and ANG II and the proliferative response elicited by these agents in MCs. AVP induces Egr-1 by both PKC-dependent and PKC-independent pathways, whereas the effects of PDGF and 5-HT are independent of PKC.