Racial and ethnic disparities in utilization of total knee arthroplasty among older women.

OBJECTIVE: To evaluate racial and ethnic disparities in utilization of total knee arthroplasty (TKA) in relation to demographic, health, and socioeconomic status variables. DESIGN: Prospective study of 102,767 Women's Health Initiative postmenopausal women initially aged 50-79, examining utilization rates of primary TKA between non-Hispanic Black/African American, non-Hispanic White, and Hispanic/Latina women (hereafter referred to as Black, White, and Hispanic). A total of 8,942 Black, 3,405 Hispanic, and 90,420 White women with linked Medicare claims data were followed until time of TKA, death, or transition from fee-for-service coverage. Absolute disparities were determined using utilization rates by racial/ethnic group and relative disparities quantified using multivariable hazards models in adjusting for age, arthritis, joint pain, mobility disability, body mass index, number of comorbidities, income, education, neighborhood socioeconomic status (SES), and geographic region. RESULTS: TKA utilization was higher among White women (10.7/1,000 person-years) compared to Black (8.5/1,000 person-years) and Hispanic women (7.6/1,000 person-years). Among women with health indicators for TKA including diagnosis of arthritis, moderate to severe joint pain, and mobility disability, Black and Hispanic women were significantly less likely to undergo TKA after adjusting for age [Black: HR (95% confidence interval) = 0.70 (0.63-0.79); Hispanic: HR = 0.58 (0.44-0.77)]. Adjustment for SES modestly attenuated the measured disparity, but significant differences remained [Black: HR = 0.75 (0.67-0.89); Hispanic: HR = 0.65 (0.47-0.89)]. CONCLUSIONS: Compared to White women, Black and Hispanic women were significantly less likely to undergo TKA after considering need and appropriateness for TKA and SES. Further investigation into personal-level and provider-level factors that may explain these disparities is warranted.

Induction of gene amplification by arsenic.

Arsenic is a well-established carcinogen in humans, but there is little evidence for its carcinogenicity in animals and it is inactive as an initiator or tumor promoter in two-stage models of carcinogenicity in mice. Two arsenic salts (sodium arsenite and sodium arsenate) induced a high frequency of methotrexate-resistant 3T6 cells, which were shown to have amplified copies of the dihydrofolate reductase gene. The ability of arsenic to induce gene amplification may relate to its carcinogenic effects in humans since amplification of oncogenes is observed in many human tumors. The inability of arsenic to induce gene mutations may relate to the negative results of arsenic in long-term animal studies and suggests that these experiments may not detect some environmental agents that act late in the carcinogenic process in humans.

Interaction of the p53-regulated protein Gadd45 with proliferating cell nuclear antigen.

GADD45 is a ubiquitously expressed mammalian gene that is induced by DNA damage and certain other stresses. Like another p53-regulated gene, p21WAF1/CIP1, whose product binds to cyclin-dependent kinases (Cdk's) and proliferating cell nuclear antigen (PCNA), GADD45 has been associated with growth suppression. Gadd45 was found to bind to PCNA, a normal component of Cdk complexes and a protein involved in DNA replication and repair. Gadd45 stimulated DNA excision repair in vitro and inhibited entry of cells into S phase. These results establish GADD45 as a link between the p53-dependent cell cycle checkpoint and DNA repair.

Assessment of epidermal growth factor receptor (EGFR, ErbB1) and HER2 (ErbB2) protein expression levels and response to lapatinib (Tykerb, GW572016) in an expanded panel of human normal and tumour cell lines.

OBJECTIVE: Lapatinib (Tykerb, GW572016), a potent inhibitor of the catalytic activities of epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2) (ErbB2), inhibits population growth of selected EGFR and HER2 overexpressing cell lines. Previous studies with a small number of cell lines suggest a correlation between overexpression of EGFR and/or HER2 and sensitivity to growth inhibition by lapatinib; however, the precise determinants of lapatinib selectivity for tumour and/or other cells remain unclear. MATERIALS AND METHODS: To clarify the determinants of its selectivity in cultured cells, lapatinib-induced cell population growth inhibition and relative EGFR and HER2 protein expression were quantified in 61 different human tumour cell lines from 12 tumour types, two oncogene transformed human cell lines and two normal human cell cultures. Using statistical tools to analyse the data, a model describing the relationship between lapatinib IC(50) (the response variable) and EGFR and HER2 expression and tissue type (explanatory variables) was derived. CONCLUSION: The results suggest that simultaneous consideration of EGFR and HER2 expression, as well as tissue type yields the best determinant of lapatinib selectivity in cultured cells.

Expression of the chicken c-src gene in COS cells.

The cellular homolog of the Rous sarcoma virus transforming gene (v-src) was cloned into a plasmid containing the simian virus 40 origin of replication and transcriptional signals. This recombinant plasmid, designated pSVOHCS11 , directs the synthesis of relatively high levels of c-src mRNA and c-src protein ( pp60c -src), when the plasmid is studied 48 to 72 h after calcium phosphate-mediated DNA transfection of COS (monkey) cells. The level of c-src mRNA synthesis is 50-fold higher than the amount of c-src RNA produced in uninfected chicken embryo fibroblasts. Furthermore, the level of pp60c -src expressed in pSVOHCS11 -transfected COS cells is approximately the same as that of pp60v -src in Rous sarcoma virus-transformed cells. Using this recombinant plasmid, we demonstrated that c-src mRNA contains sequences which map 3' to the previously identified c-src-v-src regions of homology. In view of the small amount of c-src mRNA and protein that can be isolated from uninfected cells, this transient expression system offers a convenient source of material for further analyses of the c-src gene product.

Differential response to retinoic acid of Syrian hamster embryo fibroblasts expressing v-src or v-Ha-ras oncogenes.

It has been shown that treatment of many but not all tumor cell lines with retinoids affects cell proliferation and expression of the transformed phenotype. To determine whether the response of the tumor cell to retinoids is influenced by specific oncogenes activated in the cell, we studied the action of these agents in the immortal, nontumorigenic Syrian hamster embryo cell lines DES-4 and 10W transfected with either v-Ha-ras or v-src oncogenes. In this paper we show that in transformed DES-4 cells expressing v-src, retinoic acid inhibited anchorage-independent growth, reduced saturation density, and inhibited the induction of ornithine decarboxylase by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate. In contrast, retinoic acid enhances the expression of the transformed phenotype in DES-4-derived cells that express v-Ha-ras. In these cells retinoic acid increases the number and the average size of colonies formed in soft agar. Moreover, retinoic acid enhances ornithine decarboxylase activity and acts in a synergistic fashion with 12-O-tetradecanoylphorbol-13-acetate. These results indicate that oncogenes activated in cells can indeed influence the response of cells to retinoids. Retinoic acid does not appear to alter the levels of pp60src or p21ras proteins in these cells, suggesting that retinoic acid does not affect the synthesis of these oncogene products. Furthermore, retinoic acid does not affect the protein kinase activity of pp60src. Transformed cell lines derived from 10W cells responded differently, indicating that the presence of a specific oncogene is not the only factor determining the response to retinoids. Possible mechanisms by which retinoic acid may interfere with the expression of the oncogene products are discussed.

Neoplastic transformation of normal and carcinogen-induced preneoplastic Syrian hamster embryo cells by the v-src oncogene.

The ability of cloned Rous sarcoma virus (RSV) DNA encoding the v-src oncogene to neoplastically transform normal, diploid Syrian hamster embryo (SHE) cells was examined. Transfection of RSV DNA into early passage SHE cells resulted in a low but significant number of tumors when treated cells were injected into nude mice. Tumors formed with a low frequency (two tumors out of ten sites injected) and only after a long latency period (14 weeks). In contrast to the normal SHE cells, several different carcinogen-induced preneoplastic immortal SHE cell lines were highly susceptible to transformation by the v-src oncogene to the neoplastic phenotype. Tumors formed with high efficiency and a short latency period (less than 3 weeks). Further studies were performed to determine the basis for the inefficient transformation of the normal SHE cells. NeoR clones isolated after cotransfection of SHE cells with pSV2-neo and RSV DNAs were neither morphologically altered nor immortal and did not contain detectable levels of the v-src gene product. These results suggest that neoplastic transformation by v-src DNA in the normal cells is initially suppressed. However, cells from a v-src-induced tumor expressed v-src RNA, and antibody to v-src protein precipitated from the tumor cells a 60,000-molecular-weight protein which displayed protein kinase activity. Karyotypic analyses confirmed that the tumor was derived from Syrian hamster cells and suggested that it was clonal in nature. These results indicate that the v-src oncogene was primarily responsible for neoplastic transformation of SHE cells. In contrast to the results with the v-src oncogene, our previous studies showed that v-Ha-ras oncogene alone is unable to induce neoplastic transformation of SHE cells. Furthermore, the v-myc oncogene was able to compliment v-Ha-ras to neoplastically transform SHE cells, while cotransfection with v-src plus v-myc did not increase the incidence of tumors.

Mutational activation of pp60(c-src) leads to a tumorigenic phenotype in a preneoplastic Syrian hamster embryo cell line.

Previous studies indicated that overexpression of wild-type avian c-src cannot induce neoplastic transformation of NIH 3T3 cells. In this study, we isolated and characterized novel spontaneously derived transforming mutants of avian pp60(c-src) from a Syrian hamster embryo-derived cell line, 10W, transfected with the avian c-src gene. Seventeen independently derived transfected 10W cell clones were injected into athymic nude mice. After a latency period, tumors eventually arose and were established in culture. The tumorigenic phenotype was always accompanied by the presence of the avian c-src DNA and functional expression of pp60(c-src). However, most of the tumor-derived cell lines expressed an electrophoretically altered form of pp60(c-src), suggesting mutations in src. Consistent with this hypothesis, DNAs isolated from the tumor-derived lines, but not the parental 10W cell lines, morphologically transformed NIH 3T3 cells in a focus-forming assay. We characterized pp60(c-src) in detail from three of the tumor-derived lines: 4AT, 4BT, and E2T. Two of these lines contained mutations within the exogenous c-src coding region. Line 4AT has an internal repeat of 29 amino acids immediately following Gln-513, which disrupts the spacing between the end of the kinase domain and Tyr-527, the negative regulatory site in pp60(c-src). Line 4BT has a 5-bp deletion following Phe-520, which results in loss of Tyr-527. However, the DNA sequence of the coding region of pp60(c-src) from a third line, E2T, was completely wild type. Cyanogen bromide cleavage analyses of the altered pp60(c-src) from lines 4AT and 4BT showed that Tyr-527, the site of negative regulation of c-src, is not phosphorylated, but Tyr-416, the site of in vitro autophosphorylation, is phosphorylated. However, in line E2T, Tyr-527 was phosphorylated, and Tyr-416 was phosphorylated to a lesser extent. Additionally, two proteins that indicate activation of src, p85 cortactin and p120(cas), are phosphorylated in at least six of the tumor-derived cell lines, although to a lesser extent in line E2T. These results suggest that dephosphorylation of Tyr-527 and phosphorylation of Tyr-416 correlate with activation of pp60(c-src) in the tumor-derived lines 4AT and 4BT, respectively. However, in line E2T, the high levels of pp60(c-src), in combination with a partial activation of the pp60(c-src) protein as indicated by phosphorylation of Tyr-416, appear to be involved in the neoplastic process, rather than mutation.

Evidence for multiple steps in neoplastic transformation of normal and preneoplastic Syrian hamster embryo cells following transfection with Harvey murine sarcoma virus oncogene (v-Ha-ras).

Neoplastic development of Syrian hamster embryo (SHE) cells in culture is a multistep process in which intermediate or preneoplastic cells can be identified and isolated. In an attempt to further characterize normal and preneoplastic cells, we have compared their susceptibilities to neoplastic transformation following transfection with cloned DNA of the oncogenic virus, Harvey murine sarcoma virus (HaMSV). Normal SHE cells, which are stably nontumorigenic when injected in nude mice, are competent to take up and express exogenous DNA as demonstrated by transfection experiments with pSV2-neo DNA and certain viral DNAs. SHE cells treated with 5 micrograms of HaMSV DNA per dish remained nontumorigenic. Colonies of SHE cells, isolated after cotransfection with HaMSV and pSV2-neo DNA and selection for G418 antibiotic resistance, expressed Harvey murine sarcoma virus oncogene (v-Ha-ras) RNA and were initially morphologically altered; however, all colonies senesced when subcultured. In contrast, transfection of the cells with polyoma virus DNA alone or HaMSV DNA plus MC29 viral DNA (pSVv-myc) and then injection of the cells into nude mice resulted in progressively growing tumors of hamster origin within 3 to 5 weeks. A preneoplastic cell line, DES-4, isolated after treatment of SHE cells with the human carcinogen diethylstilbestrol, was chosen for comparative analyses. These immortalized cells are nontumorigenic and excellent recipients for exogenous DNA. In contrast to SHE cells, DES-4 cells were highly susceptible to neoplastic transformation following transfection with HaMSV DNA. To further investigate the role of HaMSV DNA in the neoplastic transformation of DES-4 cells and to determine whether this occurred as a single step, clones of DES-4 cells cotransfected with pSV2-neo and HaMSV DNAs were selected by antibiotic resistance and characterized. There was a good correlation between tumorigenicity and expression of v-Ha-ras DNA; however, the clones were highly variable in terms of their latency periods in vivo and anchorage-independent growth. Neither of these two parameters correlated with the level of expression of v-Ha-ras RNA. All of the cell lines derived from tumors and reinoculated into nude mice had short latency periods in vivo, were highly anchorage independent, and had high levels of v-Ha-ras expression. These results suggest that, in these experiments, v-Ha-ras expression was necessary, but not sufficient, for the tumorigenicity of DES-4 cells and that additional changes in the cells were acquired.(ABSTRACT TRUNCATED AT 400 WORDS)

Correlation of V-src gene amplification with the tumorigenic phenotype in a Syrian hamster embryo cell line.

A preneoplastic cell line (10W) isolated after treatment of Syrian hamster embryo cells with asbestos was cotransfected with pSV2-neo DNA and Rous sarcoma virus DNA. Six of these colonies contained v-src DNA; however, none of the six initially expressed v-src RNA. Five of the clones failed to grow in soft agar (frequency, less than 10(-6)). One clone (61) grew in soft agar, but with a low frequency. Three of the clones (41, 61, and 62) were tumorigenic in nude mice and three were nontumorigenic. Cells cloned from soft agar or established from tumor explants expressed the v-src gene. The gene copy number of v-src, which was three to 10 in the original neoR clones, was increased approximately 10-fold in the soft agar-derived cell clones and tumor-derived cell lines. Cytogenetic analyses indicated that cells with amplified v-src contained double minute chromosomes. The results suggest that gene amplification influences the expression of the transfected oncogene and is a mechanism which can overcome the initial suppression of transcription of the v-src oncogene in the 10W cell line.

Separate pathways for p53 induction by ionizing radiation and N-(phosphonoacetyl)-L-aspartate.

The tumor suppressor gene product, p53, appears to be a significant participant in signaling pathways that mediate cellular responses to cytotoxic stresses. In particular, p53 appears to be a critical determinant of whether the cell lives or dies and how it progresses through the cell cycle after the cytotoxic exposure. Many of the molecular details for these signaling pathways remain to be elucidated, and whether all cytotoxic signals utilize the same pathway to increase p53 expression is not clear. Here, we demonstrate the existence of cell types in which the induction of p53 and associated G1 arrest by the antimetabolite, N-(phosphonoacetyl)-L-aspartate (PALA), is defective, whereas p53 induction and G1 arrest induced by ionizing radiation are intact. These observations demonstrate the existence of genetic defects that can alter p53 induction and associated cellular outcomes after some, but not all, cytotoxic insults and suggest distinct pathways of p53 induction by PALA and ionizing radiation.

A new ligand for the peroxisome proliferator-activated receptor-gamma (PPAR-gamma), GW7845, inhibits rat mammary carcinogenesis.

We have tested a new ligand for peroxisome proliferator-activated receptor-gamma, GW7845, as an inhibitor of experimental mammary carcinogenesis, using the classic rat model with nitrosomethylurea as carcinogen. Rats were first treated with a single dose of nitrosomethylurea (50 mg/kg body weight, i.p.). Starting 1 week later, they were fed GW7845, at either 60 or 30 mg/kg of diet, for 2 months. This agent significantly reduced tumor incidence, tumor number, and tumor weight at both doses. This is the first report of the use of a ligand for peroxisome proliferator-activated receptor-gamma to prevent experimental breast cancer.

Mouse retroviral sequences acquired by cell lines after passaging through nude mice detected by hybridization of the fms probe pSM3.

The expression of a large RNA transcript, 8.5 to 9.5 kilobases, possibly related to the fms oncogene in mouse, rat, and human tumor cells, has been described in the literature. However, the pSM3 fms probe used to detect this gene transcript contains a significant amount of the pol gene of the Susan McDonough strain of feline sarcoma virus from which it was derived. Using a fms probe which does not contain any viral pol sequences, no such "fms-related" transcripts were detected in cell lines previously reported to express the large transcripts. These cell lines did express a large 9.5-kilobase transcript which hybridized to a probe for murine leukemia virus. Partial sequence analysis of the 9.5-kilobase transcript detected with the pSM3 probe in transformed rat cells indicated sequence homology with AKV murine leukemia virus. Thus, the presence of large RNA transcripts, interpreted by us and others as being related to the oncogene fms, appears to be due to the expression of mouse retroviral sequences which hybridize to the viral pol region contained in the pSM3 fms probe. In the case of rat and human cells, such sequences appear to be acquired after the cells have been passaged in nude mice. These results should serve as a reminder of the important biohazard and data interpretation implications for investigations in which cells transfected with retroviral vector constructs are injected into nude mice, because rescue of the recombinant sequences in these cells could occur following infection by endogenous murine retroviral particles.

The characterization of novel, dual ErbB-2/EGFR, tyrosine kinase inhibitors: potential therapy for cancer.

The type I receptor tyrosine kinases constitute a family of transmembrane proteins involved in various aspects of cell growth and survival and have been implicated in the initiation and progression of several types of human malignancies. The best characterized of these proteins are the epidermal growth factor receptor (EGFR) and ErbB-2 (HER-2/neu). We have developed potent quinazoline and pyrido-[3,4-d]-pyrimidine small molecules that are dual inhibitors of ErbB-2 and EGFR. The compounds demonstrate potent in vitro inhibition of the ErbB-2 and EGFR kinase domains with IC(50)s <80 nM. Growth of ErbB-2- and EGFR-expressing tumor cell lines is inhibited at concentrations <0.5 microM. Selectivity for tumor cell growth inhibition versus normal human fibroblast growth inhibition ranges from 10- to >75-fold. Tumor growth in mouse s.c. xenograft models of the BT474 and HN5 cell lines is inhibited in a dose-responsive manner using oral doses of 10 and 30 mg/kg twice per day. In addition, the tested compounds caused a reduction of ErbB-2 and EGFR autophosphorylation in tumor fragments from these xenograft models. These data indicate that these compounds have potential use as therapy in the broad population of cancer patients overexpressing ErbB-2 and/or EGFR.

Novel tyrosine phosphorylations accompany the activation of pp60c-src during chemical carcinogenesis.

Treatment of normal Syrian hamster embryo (SHE) cells in vitro with various chemical carcinogens results in transformed preneoplastic cell lines. Continued passage of these preneoplastic cells gives rise to rare variant cells with enhanced capacity for tumorigenic growth. We have previously shown that tumor-derived SHE cell lines contain an activated proto-oncogene product, pp60c-src. Here we demonstrate that tumor-derived SHE cell lines contain several novel tyrosine phosphoproteins in addition to those found in preneoplastic parent cell lines. A correlation was observed between the activation of endogenous pp60c-src tyrosine kinase specific activity and the presence of new phosphotyrosine-containing proteins. Tyrosine phosphoproteins of approximate Mr 81 kilodaltons (kDa), 55 kDa, and 39 kDa were noted in different tumor-derived cell lines. The 81 kDa and 55 kDa proteins were membrane-associated phosphoproteins, whereas the 39 kDa protein was predominantly cytosolic. Additional signature tyrosine phosphoproteins in individual tumor-derived cell lines apparently were unique to the particular inducing carcinogen or target cell. These studies indicate that during chemical carcinogenesis, activation of the tyrosine kinase proto-oncogene protein pp60c-src coincides with the appearance of novel tyrosine phosphorylations.

Activation of pp60c-src tyrosine kinase specific activity in tumor-derived Syrian hamster embryo cells.

Tumor-derived Syrian hamster embryo (SHE) cell lines, induced in vitro by treatment with chemical carcinogens, contained increased levels of pp60c-src kinase activity compared to preneoplastic parental cell lines and normal SHE cells. The increased kinase activity did not result from an increase in the pp60c-src content of the SHE cell lines, but represented a 4-11 fold increase in pp60c-src kinase specific activity. Both the extent of phosphorylation and the velocity of pp60c-src phosphotransferase activity were increased in the tumor-derived cell lines. SHE cell lines producing chicken pp60c-src were isolated following co-transfection with plasmids bearing the chicken c-src and neoR genes. Chicken pp60c-src expressed in an asbestos-transformed, tumor-derived cell line showed an approximate 3-fold activation of tyrosine kinase activity compared to chicken pp60c-src expressed in the preneoplastic cell line. We suggest that these results indicate that activation of pp60c-src is mediated by trans-acting cellular factors present in the tumor-derived cells. Analysis of pp60c-src in normal SHE cells, preneoplastic cell lines and tumor-derived cell lines showed no alteration in the phosphorylation of tyr-527 or tyr-416, two tyrosine residues whose phosphorylation states have been associated with modulation of kinase activity. These studies indicate that the neoplastic progression of cells may be accompanied by the activation of proto-oncogene products, such as the pp60c-src tyrosine kinase, by mechanisms that may not directly involve genetic alteration of the proto-oncogene DNA sequence.

Overexpression of the Ras-related TC21/R-Ras2 protein may contribute to the development of human breast cancers.

Although experimental studies suggest that aberrant Ras function can promote the malignant progression of human breast epithelial cells, the occurrence of mutated ras genes in breast tumors is infrequent. One possible explanation for this apparent paradox is that aberrant function of the Ras-related protein TC21/R-Ras2, which causes malignant transformation of NIH 3T3 cells via upregulation of the Ras signal transduction pathway, may contribute to breast tumor development in the absence of Ras mutations. To address this possibility, we utilized two complementary approaches. First, we determined that aberrant TC21 function caused transformation of the MCF-10A human breast epithelial cell line. TC21-transformed MCF-10A cells exhibited altered cellular morphology associated with a disruption of cell-cell adherens junctions, formed colonies in soft agar, and showed enhanced motility in vitro. These alterations were similar to, but more dramatic than, those observed with oncogenic Ras-transformed MCF-10A cells. Furthermore, overexpression of normal TC21, but not Ras, also caused transformation of these cells. Second, we observed that TC21 protein expression was greatly elevated in 7 of 9 breast tumor lines when compared to untransformed MCF-10A cells. Taken together, these results support the possibility that overexpression of TC21 may contribute to aberrant growth properties of breast carcinoma cells.

Overexpression of pp60c-src is associated with altered regulation of adenylyl cyclase.

The ability of activators of the beta-adrenergic receptor to elevate intracellular cAMP levels in murine fibroblasts is enhanced upon overexpression of avian c-src [Bushman et al. (1990) Proc. natn. Acad. Sci. U.S.A. 87, 7462-7466]. To investigate the molecular basis for this effect, we prepared particulate fractions from control and pp60c-src overexpressing C3H10T1/2 fibroblasts and assessed the relative abilities of several activators of the beta-adrenergic receptor-Gs-adenylyl cyclase (AC) signal transduction pathway to stimulate the enzymatic response. Two- to three-fold increases in both the sensitivity and maximum responsiveness of AC to the beta-adrenergic agonist isoproterenol were consistently observed in fractions prepared from the c-src overexpressing cells. Interestingly, the AC response to two agents believed to act directly at the level of the G protein were either enhanced (NaF) or unaffected (GTP gamma S) by c-src overexpression. Finally, overexpression of c-src was associated with a reduced ability of both Mn2+ and forskolin to activate AC directly. These results suggest that overexpression of wild type c-src may affect two distinct steps in the regulation of AC exerting a positive effect at the level of Gs activation and a negative effect on AC itself. As no differences in the relative number or affinity of beta-adrenergic receptors, or in the level of AC, Gs alpha or G beta, were detected between control cells and those overexpressing c-src, we propose that pp60c-src overexpression results in a modification of one or more components in this signal transduction pathway.

The cost to health plans of poor glycemic control.

OBJECTIVE: We tested the hypothesis that level of glycemic control is related to medical care costs in adults with diabetes. RESEARCH DESIGN AND METHODS: Regression analysis was used to estimate the relationship between glycemic control and medical care charges for 3,017 adults with diabetes who were continuously enrolled in a large health maintenance organization (HMO) over a 4-year period. Diagnosis of diabetes was ascertained from diagnostic and pharmaceutical databases using a method with an estimated sensitivity of 0.91 and an estimated specificity of 0.99. Charges for care included defined outpatient and inpatient services. Patients who disenrolled or who died during the 4-year period were excluded from the main analysis. RESULTS: Charges for medical care for patients with diabetes from 1993 to 1995 were closely related to HbA1c level in 1992 before and after adjustment for age, sex, coronary heart disease, and hypertension. Standardized 3-year estimates of charges ranged from $10,439 for patients without comorbid conditions to $44,417 for those with heart disease and hypertension. Medical care charges increased significantly for every 1% increase above HbA1c of 7%. For a person with an HbA1c value of 6%, successive 1% increases in HbA1c resulted in cumulative increases in charges of approximately 4, 10, 20, and 30%. The increase in charges accelerated as the HbA1c value increased. For patients with diabetes only, or with diabetes plus other chronic conditions, the rate of increase in charges with HbA1c was consistent. CONCLUSIONS: HbA1c provides useful information to providers and patients regarding both health status and future medical care charges. Economic data suggest that clinicians should assign high importance to low HbA1c results and aggressively maintain the HbA1c status of patients who have low HbA1c values. For economic as well as clinical reasons, it may be beneficial to lower HbA1c when it is > 8% and to reduce cardiovascular risk factors. The medical charge data suggest that investment in clinical systems to improve diabetes care may benefit both payers and patients.

The effects of the novel, reversible epidermal growth factor receptor/ErbB-2 tyrosine kinase inhibitor, GW2016, on the growth of human normal and tumor-derived cell lines in vitro and in vivo.

The epidermal growth factor receptor (EGFR) and ErbB-2 transmembrane tyrosine kinases are currently being targeted by various mechanisms in the treatment of cancer. GW2016 is a potent inhibitor of the ErbB-2 and EGFR tyrosine kinase domains with IC50 values against purified EGFR and ErbB-2 of 10.2 and 9.8 nM, respectively. This report describes the efficacy in cell growth assays of GW2016 on human tumor cell lines overexpressing either EGFR or ErbB-2: HN5 (head and neck), A-431 (vulva), BT474 (breast), CaLu-3 (lung), and N87 (gastric). Normal human foreskin fibroblasts, nontumorigenic epithelial cells (HB4a), and nonoverexpressing tumor cells (MCF-7 and T47D) were tested as negative controls. After 3 days of compound exposure, average IC50 values for growth inhibition in the EGFR- and ErbB-2-overexpressing tumor cell lines were < 0.16 microM. The average selectivity for the tumor cells versus the human foreskin fibroblast cell line was 100-fold. Inhibition of EGFR and ErbB-2 receptor autophosphorylation and phosphorylation of the downstream modulator, AKT, was verified by Western blot analysis in the BT474 and HN5 cell lines. As a measure of cytotoxicity versus growth arrest, the HN5 and BT474 cells were assessed in an outgrowth assay after a transient exposure to GW2016. The cells were treated for 3 days in five concentrations of GW2016, and cell growth was monitored for an additional 12 days after removal of the compound. In each of these tumor cell lines, concentrations of GW2016 were reached where outgrowth did not occur. Furthermore, growth arrest and cell death were observed in parallel experiments, as determined by bromodeoxyuridine incorporation and propidium iodide staining. GW2016 treatment inhibited tumor xenograft growth of the HN5 and BT474 cells in a dose-responsive manner at 30 and 100 mg/kg orally, twice daily, with complete inhibition of tumor growth at the higher dose. Together, these results indicate that GW2016 achieves excellent potency on tumor cells with selectivity for tumor versus normal cells and suggest that GW2016 has value as a therapy for patients with tumors overexpressing either EGFR or ErbB-2.