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S Pathak

Publications and source records attributed to S Pathak.

At least 19 recordsLinked to original sources
PubMed2000

LNCaP progression model of human prostate cancer: androgen-independence and osseous metastasis.

BACKGROUND: Clinically, the lethal phenotypes of human prostate cancer are characterized by their progression to androgen-independence and their propensity to form osseous metastases. We reported previously on the establishment of androgen-independent (AI) human prostate cancer cell lines derived from androgen-dependent (AD) LNCaP cells, with androgen independence defined as the capability of prostate cancer cells to grow in castrated hosts. One of the sublines, C4-2, was found to be AI, highly tumorigenic, and metastatic, having a proclivity for metastasis to the bone. METHODS: We established the AI and bone metastatic cell sublines B2, B3, B4, and B5 from the parental C4-2 subline, using a previously established coinoculating procedure. We determined the biologic behavior of the parental and derivative LNCaP sublines in vivo and in vitro, as well as their molecular and cytogenetic characteristics. RESULTS: Unlike other human prostate cancer models, the LNCaP progression model shares remarkable similarities with human prostate cancer. We observed a comparable pattern of metastasis from the primary to the lymph node and to the axial skeleton, with a predominant phenotype of osteoblastic reaction; 25-37.5% of the animals developed paraplegia. Cytogenetic and biochemical characterizations of LNCaP sublines also indicate close similarities between human prostate cancer and the LNCaP progression model. Additional chromosomal changes were detected in B2-B5 sublines derived from C4-2 bone metastases. These LNCaP sublines were found to grow faster under anchorage-dependent but not -independent conditions. The in vitro invasion and in vivo metastatic potential of these LNCaP sublines surprisingly correlated with anchorage-dependent and not -independent growth. The derivative LNCaP sublines when cultured in vitro produced a substantially higher (20-30-fold) amount of basal steady-state concentrations of PSA than that of the parental LNCaP cells. PSA production was high initially, but was markedly reduced when the derivative cell lines were inoculated and allowed to grow long-term in vivo for the establishment of tumors and metastasis, suggesting that unknown host factors derived either from the prostate or the bone can effectively downregulate PSA expression by prostate tumor epithelium. CONCLUSIONS: The LNCaP model of human prostate cancer progression will help improve our understanding of the mechanisms of androgen-independence and osseous metastasis, and tumor-host determinants of PSA expression.

Animals↗
PubMed2000

Adenosine acts as an inhibitor of lymphoma cell growth: a major role for the A3 adenosine receptor.

In this study, we demonstrated several mechanisms exploring the inhibitory effect of low-dose adenosine on lymphoma cell growth. Adenosine, a purine nucleoside present in plasma and other extracellular fluids, acts as a regulatory molecule, by binding to G-protein associated cell-surface receptors, A1, A2 and A3. Recently we showed that low-dose adenosine released by muscle cells, inhibits tumour cell growth and thus attributes to the rarity of muscle metastases. In the present work, a cytostatic effect of adenosine on the proliferation of the Nb2-11C rat lymphoma cell line was demonstrated. This effect was mediated through the induction of cell cycle arrest in the G0/G1 phase and by decreasing the telomeric signal in these cells. Adenosine was found to exert its antiproliferative effect mainly through binding to its A3 receptor. The cytostatic anticancer activity, mediated through the A3 adenosine receptor, turns it into a potential target for the development of anticancer therapies.

Adenosine↗
PubMed2000

Anvirzel, an extract of Nerium oleander, induces cell death in human but not murine cancer cells.

The purpose of this study was to examine the mechanism(s) and differential cell-killing effects of Anvirzel, an extract of oleander (Nerium oleander; family-Apocynaceae), and its derivative compound Oleandrin on human, canine and murine tumor cells. Cells received different concentrations of Anvirzel (1.0 ng/ml to 500 microg/ml) or Oleandrin (0.01 ng/ml to 50 microg/ml) in both continuously treated and pulse-treated/recovery cultures. The cytotoxicity of these compounds was then determined. Both Anvirzel and Oleandrin were able to induce cell killing in human cancer cells, but not in murine cancer cells; the cell-killing potency of Oleandrin was greater than that of Anvirzel. Canine oral cancer cells treated with Anvirzel showed intermediate levels of response, with some abnormal metaphases and cell death resulting from the treatment. From these results we conclude that Anvirzel and Oleandrin act in a species-specific manner, and while testing the effectiveness of a new compound for cancer treatment, one must use not only murine but a variety of cancer cells, including those of human origin.

Animals↗
PubMed2000

Correlation of non-random chromosomal aberrations in lymphocytes of prostate cancer patients with specific clinical parameters.

The purpose of this research was to correlate non-random chromosomal aberrations in the peripheral blood lymphocytes (PBLs) of prostate cancer patients with specific clinical parameters. Peripheral blood samples were analyzed from 59 informative prostate cancer patients. Non-random chromosomal alterations detected in the PBLs and their correlation with any specific clinical parameters were analyzed statistically. A comparison was made between specific chromosomal abnormalities in the patients having an early (<65 years) or late (> or =65 years) age at disease onset, low-grade (Gleason grade <7) or high-grade (Gleason grade > or =7) tumors, a low (<10 ng/ml) or high (> or =10 ng/ml) prostate-specific antigen (PSA) level, and androgen-sensitive or -insensitive disease. In examining the specific chromosomal breakpoints, the regions 1p13, 2q21, 3p21, 4q13, 5q31, 6p21, 7p15, 7p13, 7q32, 10p11, 10q26, 11p15, 11p11, 14q12, and 16q12 showed breaks in at least four cases. Chromosome 15 (P=0. 045) was significantly altered in patients having a PSA value greater than or equal to 10, while it (P=0.017) and chromosome 19 (P=0.036) were significantly altered in patients having a PSA value greater than or equal to 20. In addition, chromosomes 5 (P=0.032), 8 (P=0.020), 16 (P=0.009), and 20 (P=0.047) were significantly altered in patients having a Gleason grade greater than 7. Also, chromosomes 2 (P=0.020) and 3 (P=0.044) were significantly altered in patients who had early disease onset. Additionally, chromosome 10 (P=0.041) was significantly altered in patients having metastasis, and chromosomes 4 (P=0.006) and 7 (P=0.028) were significantly altered in patients having androgen-insensitive disease. In spite of the small subset of patients, chromosome 8 (p=0.003) was significantly altered in patients having small cell carcinoma of the prostate. From these results we conclude that non-random chromosomal aberrations present in PBLs of prostate cancer patients can be correlated with specific clinical parameters. These correlations can be used to identify a prostate cancer patient's risk response to therapy.

Age of Onset↗
PubMed2000

Spontaneous regression of cutaneous melanoma in sinclair swine is associated with defective telomerase activity and extensive telomere erosion.

Recently we proposed the hypothesis that extensive telomeric association of chromosomes is an early manifestation of cell death and asked whether there are extensive telomeric associations present in metaphases of the spontaneously regressing Sinclair swine cutaneous melanoma (SSCM). Our results indicate that early passage SSCMs, in the accelerated growth phase, do not show telomeric associations but do have numerical and other specific structural abnormalities. However, the same melanoma cell lines at late passages or melanomas obtained from middle- and old-aged Sinclair swine show extensive telomeric associations in the form of dicentric, multicentric, and ring configurations. Such abnormal structures are present mostly in metaphases that are hyperploids. Increasing frequencies of apoptotic bodies were also observed in higher passage tumor cell lines obtained from younger animals or in melanomas obtained from older animals. The polymerase chain reaction (PCR)-based telomeric repeat amplification protocol (TRAP) assay shows no detectable telomerase activity in any of these regressing swine melanoma cell lines, neither in normal swine skin fibroblasts nor in nevi. However, the fetal swine (i.e., non-regressing) melanoma cells show telomerase activity. Fluorescence in situ hybridization (FISH) results using the commercially available human telomeric repeat DNA probe indicate a reduction of telomeric signals in metaphase and interphase cells of regressing melanomas. From these observations we conclude that spontaneous regression of SSCM is associated with the loss of telomerase activity and a reduction of telomeric repeats that results in the formation of multicentric and ring configurations. Such abnormal chromosome configurations are lost, following the breakage-fusion-bridge-cycles, and result in extensive DNA fragmentation, as shown by laddering experiments, and, finally, cell death.

Animals↗
PubMed2000

Osteopetrorickets.

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Bone Marrow Transplantation↗
PubMed1999

Author reply

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Journal Article↗
PubMed1999

Molecular cloning of an estrogen receptor beta subtype from the goldfish, Carassius auratus.

The brain of many teleost fish species, including the goldfish Carassius auratus, expresses exceptionally high levels of cytochrome P450 aromatase (estrogen synthetase). To begin investigating the molecular and cellular targets of estrogen action in goldfish brain, a polymerase chain reaction (PCR) cloning strategy was used to isolate an estrogen receptor (ER) complementary DNA (cDNA). The 2283-bp cDNA isolated from goldfish liver encoded a protein of 568 amino acids (aa) with an estimated molecular weight of 63,539. The goldfish ER had high overall sequence identity when compared to other vertebrate ER sequences: eel (64%), human beta subtype (59%), human alpha subtype (46%), medaka (46%), and rainbow trout (47%). The highest degree of conservation was seen in the DNA-binding (94-100%) and ligand-binding (67-79%) domains. Phylogenetic analysis of the ER gene family indicated that the goldfish and eel ER are most closely related to mammalian ERbeta subtypes, whereas previously identified fish, amphibian, and avian ER forms cluster separately with mammalian ERalpha subtypes. Using the goldfish ER cDNA (here designated gfERbeta), multiple mRNA species (3.1- 8.6 kb) were detected by Northern blot analysis in goldfish liver and ovary but expression was below detection in brain. Using reverse transcription-PCR analysis, gfERbeta mRNA was detected in forebrain, mid/hindbrain, pituitary, retina, liver, ovary, and testis. Further studies are required to determine whether an additional ERalpha subtype is present in the goldfish and whether ERalpha or ERbeta forms have evolutionary precedence in vertebrates.

Amino Acid Sequence↗
PubMed1999

Amplification of the Y chromosome in three murine tumor cell lines transformed in vivo by different human prostate cancers.

Conventional and molecular cytogenetic analyses of three murine cancer cell lines that had been induced in male athymic mice by the injection of three different human prostate cancer cell lines revealed selective amplification of the Y chromosome. In particular, analysis of metaphase and interphase nuclei by fluorescence in situ hybridization (FISH) with the mouse Y chromosome-specific DNA painting probe revealed the presence of various numbers of Y chromosomes, ranging from one to eight, with a large majority of nuclei showing two copies (46.5-60.1%). In Interphase nuclei, the Y chromosomes showed distinct morphology, allowing identification irrespective of whether the preparations were treated for 15 min or for 5 h with Colcemid, a chemical known to cause chromosome condensation. However, FISH performed on human lymphocyte cultures with chromosome-specific DNA painting probes other than the Y chromosome did not reveal condensed chromosome morphology in interphase nuclei even after 12 h of Colcemid treatment. Our FISH results indicate that (1) the Y chromosome is selectively amplified in all three cell lines; (2) the mouse Y chromosome number is comparable in both interphase and metaphase cells: (3) the Y chromosome number varies between one and eight, with a large majority of cells showing two or three copies in most interphase nuclei; (4) the condensation of the Y chromosome is not affected by the duration of Colcemid treatment but by its inherent DNA constitution; and (5) the number of copies of the Y chromosome is increased and retained not only in human prostate tumor cell lines but also in murine tumors induced by these prostate tumor cell lines.

Animals↗
PubMed1999

Aneuploidy index in blood: a potential marker for early onset, androgen response, and metastasis in human prostate cancer.

OBJECTIVES: To investigate whether the frequency of chromosome abnormalities in peripheral blood lymphocytes defined as the aneuploidy index in blood (AnIB) can be used as a clinical marker of early age onset, androgen response, and metastasis in human prostate cancer. METHODS: Peripheral blood samples were collected from 80 patients with prostate cancer, and chromosome preparations were made from 72-hour cultures after mitotic block. The AnIB of 59 informative cases was compared with several parameters, including age at disease onset, Gleason grade of tumor, clinical stage of tumor, metastasis, and prostate-specific antigen (PSA) level. RESULTS: Patients with AnIB levels greater than 3 had a significantly higher incidence of metastasis (P = 0.022), androgen-independent disease (P = 0.002), and early age at disease onset (age at diagnosis less than 65 years) (P = 0.002) compared with the patients with lower AnIB (less than 3) levels. In addition, patients with AnIB levels greater than 5 had higher PSA levels (greater than 20 ng/mL) (P = 0.029) than patients with AnIB levels less than 5. CONCLUSIONS: Chromosome abnormalities can be detected in the peripheral lymphocytes of patients with prostate cancer, and AnIB can be used as an early diagnostic and predictive marker for prostate cancer metastasis and androgen-independent disease.

Age of Onset↗
PubMed1999

Can genetic instability be studied at the single chromosome level in cancer cells? Evidence from human melanoma cells.

We evaluated whether genetic instability, which is the hallmark of cancer cells, can be investigated at the single chromosomal level. We established in culture and examined a human malignant melanoma cell line and its 11 distinct clones as well as peripheral blood cultures from the original patient by G-banding, C-banding, and silver-staining (AgNOR) techniques. There were six marker chromosomes common to most of the 11 clones and eight or nine additional marker chromosomes found in only one or in very few clones. Chromosome 1 had a pericentric inversion in the C-banded region in both the tumor and the lymphocyte metaphase spreads. This same homologue was also involved in the formation of one of the shared marker chromosomes; this marker, in turn, was rearranged to form two unique markers in one clone. Our findings suggest that genetic instability can be studied at the single chromosome level. Moreover, this study further supports our earlier contention that peripheral blood lymphocyte cultures can show chromosomal lesions that are stable markers in cancer cells.

Abdominal Neoplasms↗
PubMed1999

Amplification of telomeric DNA directly correlates with metastatic potential of human and murine cancers of various histological origin.

Telomeres, repeated DNA sequences (T2AG3)n that guard the ends of chromosomes, serve as a checkpoint for cell-cycle progression and regulate cell senescence and apoptosis. Loss of the telomeric repeats promotes genomic instability, which is the hallmark of most cancer cells. Whether this loss differs among tumor cells with malignant potential is unknown and was the goal of this study. An all-human telomeric DNA probe was used to perform fluorescence in situ hybridization (FISH) and the telomeric signals in interphase nuclei were quantitated using a computer software package. Southern blot analysis was carried out to measure terminal restriction fragment length (TRFL) in multiple cancer cell lines, including nonmetastatic and metastatic human breast, lung, prostate, colon, brain, and renal carcinomas, as well as human and murine melanoma clones and somatic cell hybrids. The metastatic capability of all cell lines, clones and somatic cell hybrids was evaluated subsequent to orthotopic implantation into nude mice. FISH preparations with telomeric DNA probes showed that the mean percent telomeric area in the metastatic nuclei was significantly greater than their nonmetastatic counterparts and Southern blotting in selected samples confirmed our findings. These data suggest that amplification of telomeres is directly correlated with invasive and metastatic potential of murine or human tumor cells.

Animals↗
PubMed1999

Tonics.

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Nonprescription Drugs↗
PubMed1999

Cell death in paclitaxel-dependent chinese hamster ovary cells is initiated by the loss of telomeric DNA repeats.

We have reported earlier that cell death in a metastatic murine melanoma cell line induced by paclitaxel and its water-soluble conjugates is mediated through the extensive erosion of telomeric repeats. The purpose of this study was to investigate if loss of telomeric repeats was also involved in cell death of Tax-18 and Tax-2-4, two paclitaxel-requiring mutant Chinese hamster ovary (CHO) cell lines. Tax-18 and Tax-2-4 cells were grown in paclitaxel-free culture medium for 24, 48, 72, and 96 h at 37 degrees C and then harvested for cytological preparations. Control cultures of both cell lines were grown in paclitaxel-supplemented medium and harvested simultaneously. We found that: 1) the frequency of telomeric associations in metaphase preparations was increased with the duration of paclitaxel-depleted culture; 2) Tax-18 cells showed a higher incidence (33.0%) of endoreduplicated metaphases at 24 h of paclitaxel-depleted culture than did Tax-2-4 cells, in which endoreduplicated metaphases were rare; 3) the frequency of polyploid cells was increased after 48, 72, and 96 h of paclitaxel-depleted culture for Tax-18 relative to that for Tax-2-4 cells; 4) both cell lines showed reductions in telomeric signals at chromosomal termini, but not in the interphase nuclei; and 5) both cell lines had shorter terminal telomeric restriction fragments after culture in paclitaxel-depleted medium. These results support our earlier observations and indicate that reduction of telomeric repeats is involved in G2/M cell arrest (endoreduplication) followed by severe DNA fragmentation, and then cell death of two CHO mutant cell lines that require paclitaxel for cell division.

Animals↗
PubMed1998

Structural alterations of chromosome 5 in twelve human prostate cancer cell lines.

Neoplastic transformation, cancer progression, and metastasis are determined by a series of well-defined changes that take place in target tissue cells. Genetic alterations associated with human prostate carcinogenesis are not well defined. Some chromosomal changes, including gain of chromosomes 7, 12, 17, and X and loss of heterozygosity in chromosomes 8p, 10q, 16q, 17p, and 18q, have been reported. We examined five newly established and eight previously established prostate cancer cell lines before and after subcutis and orthotopic injection into nude mice and observed that structural alterations of chromosome 5 were present in all of the cell lines except the parental LNCaP. The fluorescence in situ hybridization preparations with the use of whole chromosome 5 DNA painting probe confirmed our Giemsa-banding data. Alterations of chromosome 5 consisted of t(1;5)(p36;q15), t(5;?)(p11;?), del(5)(q23q35) in the SP2964(= ARCaP) cell line; t(5;8)(p15;q12), i(5)(p10), t(5;15)(q11;p11) in the SP3031 cell line; t(5;?;15) (q15;?;p11), t(5;7;14)(q31;p11-q32;q11), in the SP3173 and SP3241 cell lines (derived from the same patient); del(5)(q23-33) and t(5;7;14)(q31;p11-q32;q11) in the SP3316 cell line; t(3;5)(q21;q35) in the SP2884 cell line; t(5;5)(p15;q11) in the SP2356 cell line; i(5)(p10),t(5;?)(q23;?) in the DU-145 cell line; and i(5)(p10), t(5;?)(q11;?) and t(2;5)(q15;q15) in the PC-3 cell line. Because, in most cases, alteration of chromosome 5 resulted in the partial or complete loss of 5q, we conjectured that 5q might contain one or more tumor-suppressor genes for human prostate cancer development.

Chromosome Aberrations↗
PubMed1998

Telomeric DNA: marker for human prostate cancer development?

BACKGROUND: Telomeres that protect chromosomes at both ends are shortened with each somatic cell division through replication-dependent sequence loss at DNA termini. The chromosomes with shortened telomeres tend to become unstable, leading to cell death. Due largely to reactivation/upregulation of telomerase, a ribonucleoprotein that adds nucleotide sequences onto chromosome ends, cancer cells become immortal and neoplastically transformed. METHODS: The purpose of the present study was to study three newly established human prostate cancer cell lines and three prostate-derived fibroblastic cell cultures at different passages for telomeric DNA signal intensity, telomeric restriction fragment length (TRFL), telomerase activity, and spontaneous apoptotic index. RESULTS: Compared with the three fibroblastic cell cultures, the three new prostate cancer cell lines showed: 1) telomerase activity, 2) stronger telomeric signals, 3) relatively longer TRFLs, and 4) much lower apoptotic indices. On the other hand, three fibroblastic cell cultures showed: 1) no telomerase activity, 2) weaker telomeric signals, 3) shorter TRFLs (fibroblasts derived from surrounding tissue of prostate tumor showed intermediate TRFLs), and 4) comparatively higher apoptotic indices. CONCLUSIONS: Based on these results, we conclude that telomeric DNA signal intensity, TRFL, and telomerase activity can be used to distinguish prostate cancer cells from adjacent fibroblasts.

Apoptosis↗