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M H Kraus

Publications and source records attributed to M H Kraus.

At least 37 records · Page 2Linked to original sources
PubMed1991

Oncogenic potential of erbB-2 in human mammary epithelial cells.

Introduction of the normal erbB-2 gene into immortalized human mammary epithelial cells (184B5) by transfection conferred a growth advantage to these cells both in vitro and in vivo. The 184B5 cells overexpressing erbB-2 formed colonies in semi-solid medium, frequently induced transient nodules in athymic mice and produced progressive tumors in vivo at a low frequency. Those tumors which did arise from erbB-2-transfected cells displayed substantially higher levels of normal gp185erb-2 protein when compared to the original transfectants, consistent with their selection for increased erbB-2 expression. Introduction of genes encoding genetically altered erbB-2 molecules into 184B5 cells increased their colony-forming efficiency and converted the cells to a tumorigenic phenotype at a high frequency. When the biological and biochemical properties of human mammary carcinoma cell lines known to overexpress erbB-2 were compared to the transfected 184B5 lines, they behaved most like those overexpressing the normal erbB-2 protein. Results indicate that overexpression of normal erbB-2 may directly contribute to the transformation of human mammary epithelium if sufficient levels of erbB-2 protein are expressed or if the erbB-2 gene is genetically altered.

Animals↗
PubMed1990

Increased erbB-2 gene copies and expression in multiple stages of breast cancer.

In order to examine the role of the erbB-2 oncogene in human breast cancer, gene amplification and expression were examined in multiple stages of tumor progression. Gene amplification ranging from 2-fold to 32-fold was found in 30 (29%) of 130 cases analyzed. Expression of the receptor-like gene product was determined by a combination of Western immunoblotting and immunohistochemistry. In each case of gene amplification, there was high level overexpression (+ + +) of the protein product. In an additional 29 of 111 cases in which expression was studied (26%), there was moderate level overexpression (+ +) of erbB-2 in the absence of gene amplification. Amplification and overexpression of the erbB-2 gene were found in early clinical stages of breast cancer as well as in more advanced cases. In 23 patients, gene number and level of gene expression were equivalent in the primary tumor site compared with single or multiple metastatic sites in regional lymph nodes. Using a combination of immunohistochemistry and in situ cytohybridization, high (+ + +) and moderate (+ +) level overexpression were homogeneously present in all malignant epithelial cells within histological sections of both primary and metastatic tumor. The intraductal component of carcinoma was identified in sections from 16 invasive primary tumors. erbB-2 gene expression in the intraductal lesions was equivalent to or exceeded expression in the infiltrating components of these tumors. Because erbB-2 alterations are (a) present in all clinical stages, (b) maintained during metastatic spread, (c) homogeneously present throughout tumor sections, and (d) present in the in situ as well as infiltrating component, we conclude that these alterations are selected for early and may be important in the initiation of certain mammary cancer.

Breast Neoplasms↗
PubMed1990

Growth factor-regulated pathways in epithelial cell proliferation.

Investigations of the pathways regulating normal growth of epithelial cells have revealed the existence of two major growth-factor signaling cascades required for proliferation. One pathway is activated by IGF-1 or high insulin concentration. The other is triggered by EGF, TGF alpha, or members of the FGF family, including the recently discovered epithelial-cell-specific growth factor, designated keratinocyte growth factor (KGF). Its expression pattern in vivo suggests that KGF plays an important normal physiologic role as a stromal effector of epithelial cell proliferation. Oncogenes, which represent constitutively activated forms of genes critically involved in growth-factor signaling pathways, specifically abrogate the requirement for mitogens of the EGF pathway. Examples of such genes include the erbB/EGF receptor and erbB-2, which encode structurally related receptor proteins and are often amplified and/or overexpressed in epithelial malignancies. Employing reduced stringency hybridization with v-erbB as a probe, we recently identified a third member of this receptor family, designated erbB-3. cDNA cloning revealed a predicted 148-kD transmembrane polypeptide with structural features similar to those of the EGF receptor. Normal erbB-3 expression in keratinocytes and glandular epithelium suggests its physiologic role in these cell types. Moreover, markedly elevated erbB-3 mRNA levels in certain mammary tumor cell lines suggest that increased erbB-3 expression may also play a role in some human epithelial malignancies.

Animals↗
PubMed1990

Implications of erbB-2 overexpression for basic science and clinical medicine.

Overexpression of the Epidermal Growth Factor (EGF) Receptor gene and the related erbB-2 gene has been identified in human cancers derived from a variety of tissues. The overexpression of the encoded growth factor receptor proteins is functionally related to the development of the tumor. This observation has important potential consequences for the improved diagnosis and treatment of cancer. Overexpression of these proteins also provides experimental systems that facilitate the study of growth factor signal transduction.

Animals↗
PubMed1989

Amplification, overexpression, and rearrangement of the erbB-2 protooncogene in primary human stomach carcinomas.

Four of 51 primary gastric carcinomas exhibited amplification of the erbB-2 protooncogene ranging from 2- to 8-fold. In three cases gene amplification affected erbB-2 alleles of normal gene structure as determined by Southern blot analysis. In addition, one tumor displayed gene amplification of an apparently rearranged erbB-2 allele. Analysis of the rearranged allele revealed a structural alteration consistent with an internal deletion of approximately 2 kilobase pairs within the erbB-2 gene. Quantitation of erbB-2 mRNA in these tumors demonstrated that gene amplification coincided with overexpression of erbB-2 mRNA ranging from 8- to 32-fold above levels observed in stomach tumors without gene amplification. Furthermore, in one of the tumors with amplified normal size erbB-2 restriction fragments, elevated erbB-2 mRNA levels consisted of the normal size 5-kilobase transcript. Thus, overexpression of normal size erbB-2 mRNA accompanies gene amplification in primary stomach tumors. In addition, evidence for erbB-2 gene rearrangement suggests a role for such alteration in the development of certain gastric carcinomas.

Blotting, Northern↗
PubMed1989

Localization of the human erbB-2 gene on normal and rearranged chromosomes 17 to bands q12-21.32.

Through the use of a cDNA probe, the human erbB-2 gene was localized by in situ hybridization of normal human chromosomes at 17q11-q21. In situ hybridization of chromosomes derived from fibroblasts carrying a constitutional 15;17t(q22.3;q11.21) translocation showed that the erbB-2 gene was relocated on the rearranged chromosome 15. These results as well as grain localization on prophase chromosomes locate the erbB-2 gene at 17q12-q21.32. This localization may facilitate the search for human malignancies with chromosome changes involving the erbB-2 gene.

Base Sequence↗
PubMed1989

Isolation and characterization of ERBB3, a third member of the ERBB/epidermal growth factor receptor family: evidence for overexpression in a subset of human mammary tumors.

A related DNA fragment distinct from the epidermal growth factor receptor and ERBB2 genes was detected by reduced stringency hybridization of v-erbB to normal genomic human DNA. Characterization of the cloned DNA fragment mapped the region of v-erbB homology to three exons with closest identity of 64% and 67% to a contiguous region within the tyrosine kinase domains of the epidermal growth factor receptor and ERBB2 proteins, respectively. cDNA cloning revealed a predicted 148-kDa transmembrane polypeptide with structural features identifying it as a member of the ERBB gene family, prompting us to designate the gene as ERBB3. It was mapped to human chromosome 12q13 and was shown to be expressed as a 6.2-kilobase transcript in a variety of normal tissues of epithelial origin. Markedly elevated ERBB3 mRNA levels were demonstrated in certain human mammary tumor cell lines. These findings suggest that increased ERBB3 expression, as in the case of epidermal growth factor receptor and ERBB2, may play a role in some human malignancies.

Amino Acid Sequence↗
PubMed1989

Overexpression of erbB-2 or EGF receptor proteins present in early stage mammary carcinoma is detected simultaneously in matched primary tumors and regional metastases.

Membrane protein levels of erbB-2 and epidermal growth factor (EGF) receptor as well as gene aberrations affecting these proto-oncogenes in human mammary cancer were determined in primary and metastatic lesions. Among 57 patients erbB-2 gene amplification was detected in 11 tumors (19%). In 10 of these patients where expression levels could be assayed gene amplification was associated with a high level of erbB-2 protein. In contrast, EGF receptor gene amplification with over-expression of the protein product was observed in 2 tumors (4%). In addition, 14 out of 53 (26%) primary tumors exhibited moderately increased erbB-2 protein levels in the absence of gene amplification. Similar aberrations resulting in overexpression of EGF receptor protein without detectable gene amplification were associated with 2 tumors (4%) among 47 patients analyzed. In 7 patients, expression level and gene copy numbers of erbB-2 or EGF receptor were similarly altered in the primary tumor and metastatic lesions derived from the same patient. Concordance of increased receptor gene expression in primary and metastatic lesions combined with the observation that such alterations are detectable as early as stage I and II mammary tumors, suggests that overexpression of erbB protooncogene family members can develop early in breast cancer and is maintained during tumor progression. Comparison of erbB-2 overexpression with clinical disease parameters revealed a correlation of this alteration with inflammatory mammary carcinoma (P = 0.042) implying an association of elevated erbB-2 protein levels with enhanced malignancy of the tumor cell in vivo.

Breast Neoplasms↗
PubMed1989

Autocrine interaction between TGF alpha and the EGF-receptor: quantitative requirements for induction of the malignant phenotype.

Alterations affecting the epidermal growth factor (EGF)/transforming growth factor alpha (TGF alpha)-responsive mitogenic pathway are frequently detected in malignancies. In particular, the EGF-receptor (EGFR) molecule has been found overexpressed in a number of human tumors, and TGF alpha is produced by a large array of tumor cells. Gene transfer experiments have previously demonstrated that expression of either TGF alpha or EGFR alone is not sufficient to induce the transformed phenotype in NIH3T3 cells. In this study we sought to investigate the biological effect of expression of TGF alpha and high levels of EGFR in this model system. We demonstrate that the gene for TGF alpha acts as a potent oncogene in NIH3T3 cells overexpressing EGFR (NIH-EGFR, greater than 10(6) EGFR). We further show that TGF alpha directly stimulates proliferation of the cell in which it is produced and provide evidence that the extracellular compartment of the transformed cell is the major site of interaction between TGF alpha and EGFR. Analysis of human tumor cell lines revealed a strong correlation between expression of TGF alpha and overexpression of EGFR. Moreover, high levels of EGF-independent tyrosine phosphorylation of the EGFR were detected both in NIH-EGFR expressing TGF alpha and in high EGFR and TGF alpha coexpressing human tumor cell lines. Thus, the two events instituting the EGFR/TGF alpha autocrine loop responsible for transformation in vitro may play a role in the development of some human malignancies.

Cell Transformation, Neoplastic↗
PubMed1988

Activated H-ras oncogenes in human kidney tumors.

Two H-ras oncogenes were detected by NIH/3T3 transfection assay out of 16 primary kidney tumors, 15 renal cell carcinomas (RCC), and one transitional cell carcinoma in 16 patients. Analysis of ras Mr 21,000 protein suggested single point mutations within codon 12 and 61 in each case. The restriction endonuclease analysis of H-ras gene at codon 12 confirmed this in one of them, and the remaining 15 tumors did not have a mutation at this site. DNAs from the noncancerous portions of the kidney with codon 12 mutated tumor, but not leukocytes from the same patient, showed an abnormal resistance to the endonucleases MspI and HpaII, suggesting a presence of codon 12 mutated H-ras gene in the noncancerous cells. No amplification of ras genes was detected in the 16 tumors analyzed. In one of eight tumors from patients heterozygous for H-ras related BamHI restriction fragments, one allele was lost in the tumor but not in the noncancerous portion of the same kidney. Although cytogenetic studies have previously suggested nonrandom involvement of c-raf-1 gene in RCC, no abnormality in the size nor amount of raf transcript was detected in the 15 RCCs. Our results thus indicated that the genetic lesions affecting ras genes do occur in human RCC, and probably serve as one of multisteps in the carcinogenic process.

Alleles↗
PubMed1988

12th codon mutation resulting in c-N-ras activation in acute myelogenous leukemia.

Activation of the cellular oncogene c-N-ras has been frequently observed in DNA from leukemic cells in acute myeloid leukemia (AML). Ras gene activation sufficient to mediate in vitro transformation and rodent tumorigenesis usually results from point mutations and amino acid substitutions in the 12th or 61st codons. In AML and the related myelodysplastic syndromes, amino acid substitution at the 13th codon has been observed. An activated c-N-ras gene from a 45-year-old patient with AML was isolated by transfection analysis and subjected to molecular cloning and sequence analysis. A point mutation of the 12th codon (GGT to GAT) resulting in aspartic acid substitution for glycine was observed. In other neoplasms such as colon cancer, specific ras mutations occur predominantly (e.g., K-ras, codon 12). This predominance has been of demonstrable value in analyzing large cohorts for ras activation with techniques that are rapid and economical, such as oligonucleotide hybridization. It had previously been thought that such a predominance for activation of c-N-ras at codon 13 existed in AML; however, this study in concert with others underscores the importance of 12th codon c-N-ras mutations, along with 13th and 61st codon mutations in the molecular pathogenesis of AML. Guanylate to adenylate transition mutations are commonly observed in AML and may provide insight into potential environmental leukemogens. Addressing all commonly prevalent ras activating mutations bears impact in the future design of molecular surveys of the role of ras activation in leukemogenesis.

Amino Acid Sequence↗
PubMed1987

erbB-2 is a potent oncogene when overexpressed in NIH/3T3 cells.

A wide variety of human tumors contain an amplified or overexpressed erbB-2 gene, which encodes a growth factor receptor-like protein. When erbB-2 complementary DNA was expressed in NIH/3T3 cells under the control of the SV40 promoter, the gene lacked transforming activity despite expression of detectable levels of the erbB-2 protein. A further five- to tenfold increase in its expression under influence of the long terminal repeat of Moloney murine leukemia virus was associated with activation of erbB-2 as a potent oncogene. The high levels of the erbB-2 product associated with malignant transformation of NIH/3T3 cells were observed in human mammary tumor cells that overexpressed this gene. These findings demonstrate a new mechanism for acquisition of oncogenic properties by genes encoding growth factor receptor-like proteins and provide a functional basis for the role of their overexpression in the development of human malignancies.

Animals↗
PubMed1987

Overexpression of the EGF receptor-related proto-oncogene erbB-2 in human mammary tumor cell lines by different molecular mechanisms.

Amplification of the erbB/EGF receptor and a structurally related gene, designated erbB-2, have previously been detected in a variety of human tumors. In a series of human mammary tumor cell lines, analysis of transcripts of these genes revealed elevated levels of one or the other in more than 60% of tumors analyzed. Eight cell lines demonstrated erbB-2 mRNA levels ranging from 4- to 128-fold above those of normal controls. erbB-2 expression was evaluated in comparison to the expression level of actin observed in these cell lines. There was no evidence of an aberrantly sized erbB-2 transcript in any of these lines. Immunoblot analysis indicated elevation in levels of the 185-kd product of the erbB-2 gene expressed by these cells. In four lines erbB-2 gene amplification in the absence of an apparent gene rearrangement was demonstrated. In a representative cell line of this type, SK-BR-3, the amplified erbB-2 gene copies were located in an aberrant chromosomal location. Four additional cell lines, which demonstrated 4- to 8-fold overexpression of erbB-2 mRNA, did not exhibit gene amplification. In a representative cell line of this type ZR-75-1, an apparently normal chromosomal location was found for the erbB-2 gene. Our findings indicate that overexpression of the erbB-2 gene in mammary tumor cell lines is frequent and associated with different genetic abnormalities.

Breast Neoplasms↗
PubMed1987

Human HER2 (neu) promoter: evidence for multiple mechanisms for transcriptional initiation.

We localized the 5' region of the human gene HER2 in a cloned fragment of genomic DNA. This clone contained exons 1 to 4 of HER2, spanning the coding sequence for the first 191 amino acids. The promoter region of HER2 was identified upstream to exon 1 by nuclease S1 mapping and by a functional assay in which the promoter region drives the expression of a chloramphenicol acetyltransferase gene. The HER2 promoter is different from the promoter of the epidermal growth factor receptor gene (HER1), and the GC boxes which are typical of the promoter of the epidermal growth factor receptor gene are absent from the HER2 promoter. One major and two minor RNA start sites located at nucleotides 178, 244, and 257 upstream to the initiator ATG were identified. The first one is 21 and 70 base pairs downstream from typical TATAA and CAAT boxes, respectively. This indicates that transcription of HER2/neu can be regulated by a mechanism involving a TATA box, as well as by other unidentified regulatory elements.

Base Sequence↗