Biomedical subjects
Publications and source records attributed to S Pathak.
We review the literature dealing with genetic alterations in human prostate cancer. We also discuss genetic predisposition and the roles of various proto-oncogenes and tumor-suppressor genes in prostate cancer initiation, progression, and metastasis. The role of telomere dynamics in prostate cancer metastasis and the induction of apoptosis is also briefly discussed.
The clastogenicity of lobeline and possible interactions between lobeline and ethyl alcohol were investigated in a mutagen-sensitivity assay on cultures of human lymphoblastoid cell lines. Lobeline (10(-6) M) and ethyl alcohol (1% and 2%) were added to the cultures alone or in different combinations prior to or simultaneously with bleomycin treatment. The number of chromatid breaks per cell served as the indicator of clastogenicity. Lobeline alone was not clastogenic, but there was a marked increase in genetic damage resulting from a coclastogenic interaction between lobeline and ethyl alcohol. These data emphasize the significance of interactions between compounds that may increase genotoxicity in cells exposed to mutagenic environments.
Results of flow cytometric DNA content and cytogenetic analyses of six neoplasms representing the spectrum of the morphologic subtypes of renal cell neoplasms are compared. Flow cytometric determinations of DNA diploidy and near diploidy in two renal cortical neoplasms correlated with modal chromosome numbers; however, in three of four neoplasms with a highly aneuploid DNA content, the modal chromosome numbers indicated diploidy or near-diploidy. Our data suggest that the short-term culture conditions used in cytogenetic analysis may favor growth of cells with diploid or near-diploid DNA content. This may explain the discrepancy frequently observed between results obtained using flow cytometry and karyotyping after short-term culture. We also observed (1) abnormalities in the short arm of chromosome 3 in all three nonpapillary neoplasms, (both clear and granular cell types); (2) aberrations in chromosomes 3 and 17 in the two papillary tumors; and (3) normal chromosome 3 in the presence of various random karyotypic anomalies including telomeric associations and a pseudo-diploid modal chromosome number in the only oncocytic neoplasm studied.
The genomic activity of nucleolar organizer regions (NORs) in eight human B-cell lymphoblastoid cell lines was studied following the routinely used Ag-NOR technique. The results demonstrate that (a) Ag-NORs are located in the short arms of D- and G-group chromosomes, (b) two out of eight cell lines have 66.7% and 49.0% of metaphases, respectively, with 9 to 10 active Ag-NORs, and (c) as a whole, Ag-NOR activity is much higher in B-cell lines as compared with conventional 72-hr peripheral blood lymphocyte (T-cell) harvests.
Giemsa-banding analysis performed on a newly established metastatic osteosarcoma cell line (SP-388) that was passaged through the nude mouse revealed a hypodiploid stemline number of 39 chromosomes. This cell line showed both numerical and structural abnormalities, including the abnormally banded region in certain marker chromosomes. Chromosomes 3, 15, 17 and the X were the most frequently absent elements of this tumor. Segments of chromosomes 3, 15 and X could not be identified even in rearranged chromosomes (Ml to M15). We suggest that more cases of osteosarcoma should be studied so that specific primary and secondary chromosomal anomalies can be identified in human osteosarcoma.
Constitutional chromosome abnormalities that may predispose a group of individuals to develop certain neoplasms have been reported for some human solid tumors. Deletions of 13q in retinoblastoma, 11p in Wilms' tumor, 1p in neuroblastoma, 3p in renal cell carcinoma, 5q in colorectal carcinoma and 22q in meningioma are examples of such anomalies. In breast carcinoma, a specific cytogenetic defect has not been conclusively identified. We have studied Phytohemagglutinin-stimulated lymphocytes of 76 breast cancer patients, 68 predisposed family members, 40 controls, and 30 additional controls with lung cancer to determine whether nonrandom chromosome defects are present. From each sample 100, G-or Q-banded metaphase spreads were studied for rearrangements. A marked clustering of alterations in the long arm of chromosome no. 1 (q11-22) was seen in breast cancer patients and in some predisposed family members. Alterations in 1q were present in 1% to 3% of metaphases, and included translocations to chromosomes 3, 6, 7, 9, 12, 15, 17, 18, 21 and the X; deletion of 1q, or pericentric inversion. Twelve out of 62 (19.3%) familial cases, 3 out of 14 (21.4%) sporadic cases, 9 out of 68 (13.2%) predisposed cases and 2 out of 40 (5%) control cases showed 1q alterations. None of the 30 lung cancer patients showed chromosome 1 anomaly in this region. This is consistent with the reports on primary breast tumor tissues, cell lines and pleural effusions where 1q defects have been reported. We conclude that chromosome 1q rearrangement might be one of the primary lesions specifically associated with the development of breast cancer.
Cytogenetic analyses of eight human lymphoblastoid cell lines that were established by a new procedure using B-cell growth factor (BCGF) and interleukin-4 (IL-4) revealed that three cell lines (37.5%) showed structural anomalies in more than 97% of their metaphases, whereas others were predominantly normal diploid. Our results indicate that a) the structural anomalies seen in three cell lines were not induced by culture technique but were constitutional defects present in donors' peripheral blood samples; b) one donor, whose blood gave rise to cell line BCDI, is a constitutional mosaic because both normal diploid and altered metaphases were present; and c) genetic instability should be monitored in regular blood donors because some of them may harbor blood-mediated clastogen or chromosome breakage factor(s) that could induce higher rates of recombinations in somatic cells of some recipients and thus may potentiate such individuals to develop certain types of malignancies.
We have investigated amplification and expression of the epidermal growth factor (EGF)-receptor gene and the multidrug-resistance (MDRI) gene in a newly established lung adenocarcinoma cell line and its subcell lines. Of these cell lines, the EGF-receptor was amplified (64-fold) and rearranged (6.5 and 5.4 Kb with EcoRI restriction) in an early passage cell line, DMS-4CS. MDRI gene amplification (10.5-fold), accompanied by rearrangement (4.6 and 3.7 Kb with Hind III restriction), was found in the same cell line. All other subcell lines derived from DMS-4C5 failed to demonstrate any amplification of these genes. Moreover, mRNA expression of these two genes was not overproduced. Our findings seem to indicate that highly selected cells at an early stage have undergone spontaneous amplification of these genes. However, cells containing such amplified DNA sequences may exhibit growth disadvantage, and, therefore, the amplified DNA sequences were not present in the sublines. The cytogenetic study demonstrated that early passage cells, DMS-4C6, only showed one unique marker chromosome, M10, which may represent amplification of these genes in question.
Using the trypsin-Giemsa staining technique, cytogenetic analysis was done to determine the karyotypic characteristics in cells from the early nontumorigenic passage 12 and the late tumorigenic passage 147 of the human breast milk-derived cell line HBL-100. Acquisition of exclusive marker chromosomes in the late passage of HBL-100 may be responsible for the tumorigenic behavior of these cells in athymic nude mice.
We determined the conditions necessary for a metastatic clone of the K-1735 melanoma to become dominant over nonmetastatic clones. Different mixtures of metastatic and low or nonmetastatic cells which can be identified by detailed karyotype analysis were injected into the subcutis of syngeneic C3H/HeN and allogeneic nude mice. Early (small) and late (large) subcutaneous tumors were removed and enzymatically dissociated, and cell cultures were established. The clonal composition of the cultures was determined by cytogenetic analysis. In syngeneic mice, dominance by the metastatic clone occurred only when the initial inoculum consisted of at least 5% metastatic and 95% nonmetastatic cells. In nude mice, dominance by the metastatic clone occurred even with an inoculum of 1% metastatic and 99% nonmetastatic cells, suggesting that host immunity plays a major role in this tumor system.
Cytogenetic analysis performed on 11 human malignant melanoma cell lines that were passaged through nude mice revealed both numerical and structural types of chromosomal defects. Banding analysis showed structural anomalies in chromosomes 1, 3, 5, 6, 7, 9, 10, 11, 14 and 15. Of these, the most frequently involved chromosomes were 6, 7, and 9. Chromosomes 3 and 11 were next with chromosomes 5 and 10, the least involved. Our results were very similar to results published in the literature on melanoma cytogenetics except that we found additional chromosomal alterations. Most frequently involved structural anomalies of the short arm of chromosome 9 and the long arm of chromosome 6 have been interpreted as primary and secondary defects, respectively, in melanocyte oncogenesis.
We herein propose that specific chromosomal aberrations associated with specific neoplasms are not necessarily inherited as a constitutional trait. High-risk individuals may have a tendency to undergo specific somatic mutations or chromosomal rearrangements at a relatively low frequency in all tissues as mosaicism. This may potentiate the development of specific somatic cancers. Our hypothesis may be applicable to both hereditary and sporadic types of neoplasms.
A quantitative measurement of the prophase Giemsa banding patterns in chromosome 20 of the peripheral blood samples obtained from seven patients with medullary carcinoma of the thyroid (MCT), three nonsymptomatic family members of MCT patients, and three normal controls has revealed no differences in the short arms of the two homologs. More specifically, measurements of band from 20p 12.1 to 20p 12.3 and statistical analysis of the mean ratio between these bands have given no indication of intersitial deletion in chromosome 20p of MCT patients.
The effect of aqueous extract of Moringa oleifera Lam. (roots) has been studied on histoarchitecture of the uterus during pre and post-implantation stages in rats so as to elucidate its antifertility mode of action. The histoarchitecture of the uterus of control pregnant rat had revealed a clear-cut close apposition of the uterine endometrium with reduced lumen and loose stroma. There was a prominent appearance of deciduoma and the uterine glands were enlarged. Glandular cells showed hypertrophy and in the endometrium the leucocytic infiltration was increased. When the aqueous extract of M. oleifera Lam. was administered, no deciduoma was observed on day 5th of pregnancy and the luminal epithelium remained unstimulated. The lumen was enlarged and the uterus was non-oedematous. It has been concluded that the administration of aqueous extract of M. oleifera Lam. to pregnant rats could not stimulate the uterus which remained non-receptive throughout the period of treatment, therefore, the fertilized eggs may not be welcomed by the unprepared uterus.
An improved technique for cytogenetic analysis of primary human solid tumors has been developed using an adhesive-tumor-cell culture system. While the previously described in situ harvesting procedure yielded highly condensed chromosome morphology and inadequate metaphase spread, the newly described harvesting procedures have yielded superior quality metaphase morphology and banding patterns. Cytogenetic analysis was successfully carried out on ten primary lung tumors and eight nonmalignant "normal" lung tissues. This procedure is now routinely used in this laboratory for other solid tumor cytogenetic analysis.
An adenovirus type 2-transformed rat embryo brain cell line (F 17 A2AS) and two of its subclones (F 17 CI, F 17 C2) have been studied using chromosome banding and flow cytometric techniques. In determining the modal chromosome number, a bimodal distribution was observed in each of the cell lines. In each case the first numerical mode fell in the hypertriploid or hypotetraploid range while the second represented a mode in the hypertetraploid range. Analysis of Giemsa-banded karyotypes revealed the presence of several marker chromosomes. In most cases the origins of the markers could be established from their characteristics Giemsa-banding patterns. In particular, chromosome 2 was involved in the formation of several marker chromosomes. The DNA content analysis confirmed the bimodal chromosome distribution with values in the near tetraploid and near pentaploid range for each cell line.
The karyotypes of two Syrian hamster cell lines transformed by N-methyl-N'-nitro-N-nitrosoguanidine have been analyzed using high resolution G-banding technique. The change of gene dosage appears to be the main feature of the chromosome aberrations. One of the cell lines (BHLB4) has been passaged in vitro for 68 times and has a pseudodiploid chromosome number of 44. The most common feature of aberrations of this cell line is monosomy of chromosome 15 and in addition trisomy of chromosome 8. The other cell line (HEC5) was newly transformed, having a modal chromosome number of 50. In spite of the occurrence of trisomy of some autosomes, monosomy of chromosome 15 was still evident. No obvious structural changes were found even in G-banded prophase chromosomes. Our observations support the previous report on the monosomy of chromosome 15, as the most common feature of virally- and chemically-transformed Syrian hamster cell lines.
In the current study, attempts were made to identify any products of normal breast cell genes, that may become inactivated in the malignant counterparts. Using an immune-tolerization/immunization procedure of generating antibody, two different cell-surface glycoproteins termed luminal epithelial antigen, LEA.92 and LEA.135 were identified. LEA.92 and LEA.135 expressions on MEC in a culture model-system, that reflect various steps of neoplastic transformation were detected on normal or immortalized MEC lines that were non-tumorigenic in nude mice. Furthermore, no rearrangement of chromosome 1 was observed in those cells. In contrast, both glycoproteins were undetectable on oncogenically transformed or established lines of mammary carcinoma cells that were tumorigenic. LEA.92 or LEA.135 negative cell lines exhibited a partial deletion of their chromosome 1. In tissue sections, LEA.92 expression was detected on the apical plasma membrane of normal and hyperplastic but not on the malignant mammary or extramammary epithelial cells (MEC). However, unlike LEA.92, LEA.135 was detected on certain cases of primary breast carcinoma cells, irrespective of morphological differentiation, in tissue sections.