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Biomedical subjects

N Bhattacharya

Publications and source records attributed to N Bhattacharya.

At least 19 recordsLinked to original sources
PubMed2003

Allelic imbalance at chromosome 11 in head and neck squamous cell carcinoma in an Indian patient population.

BACKGROUND: Genetic instability of chromosome 11 is a frequent event in many solid tumours, including head and neck squamous cell carcinoma (HNSCC). AIMS: To perform allelic imbalance analysis of cytogenetically mapped altered regions of human chromosome 11 in patients with HNSCC from eastern India. METHODS: Genomic alterations were investigated using highly polymorphic microsatellite markers in both HNSCC and leukoplakia tissues. RESULTS: Microsatellite markers D11S1758 from 11p13-15 and D11S925 from 11q23.3-24 had the highest frequency (38% and 32%, respectively) of loss of heterozygosity among all the markers analysed. Allelic loss at the marker D11S925 was seen in both leukoplakia and in all stages of HNSCC tumour tissues suggesting that it is an early event in HNSCC tumorigenesis. Microsatellite size alteration was also found to be high (> 20%) in several markers. In leukoplakia samples microsatellite instability was seen at a higher frequency than loss of the allele, indicating such alterations might initiate the process of tumorigenesis in HNSCC. CONCLUSIONS: The high rate of chromosomal alterations at 11q21-24 in HNSCC suggests the presence of a putative tumour suppressor gene in this region.

Adult↗
PubMed2002

Implementation of quantum search algorithm using classical Fourier optics.

We report on an experiment on Grover's quantum search algorithm showing that classical waves can search a N-item database as efficiently as quantum mechanics can. The transverse beam profile of a short laser pulse is processed iteratively as the pulse bounces back and forth between two mirrors. We directly observe the sought item being found in approximately square root[N] iterations, in the form of a growing intensity peak on this profile. Although the lack of quantum entanglement limits the size of our database, our results show that entanglement is neither necessary for the algorithm itself, nor for its efficiency.

Journal Article↗
PubMed2002

Human fetal adrenal transplant: a possible role in relieving intractable pain in advanced rheumatoid arthritis.

BACKGROUND: The art of transplant surgery has gone a long way in establishing itself as an important discipline in medicine with the support of molecular biology, immunology, biochemistry, etc., as the ultimate treatment for the restoration of function of a failing organ. With the progressive increase in the life expectancy of human beings, there is an increasing discrepancy in the demand and supply of organ grafts. A less efficient alternative could be synthetic or mechanical grafts. Nucleated cell therapy, that is, cellular transplant, is a promising new area of study with its proven efficacy in neuro-degenerative disorders, hematopoietic disorders, diabetes and trauma-induced tissue loss, to name a few. Human fetal cell/tissue with its intrinsic hypo-antigenic advantage (up to 20 weeks of study), could be an interesting area of cellular/tissue transplant. Our research group has earlier reported on the safe use of umbilical cord whole blood and the successful transplant of a human fetal lung, heart, pancreas, liver, thymus, in an artificially prepared vascular subcutaneous axillary fold in which there was no feature of hyper-acute, acute or chronic rejection of the graft in HLA- and sex-randomized adult recipients, without concomitant immunosuppressives or radiation of the host to potentiate the survival of the fetal graft (within 20 weeks of gestation) within the lowest observation period of one month. The present study was aimed at examining the role of developing fetal adrenal transplants for patients with rheumatoid arthritis and severe pain due to involvement of inflammatory and neuropathic components. MATERIALS AND METHOD: Ten cases were enrolled in the present study after thorough informed consent and approval by the ethical committee of the institute. The age of the patients varied from 50 to 76 years and the group was comprised of three males and seven females. The age of the adrenal grafts varied from 16 to 20 weeks and these were collected from mothers admitted for hysterotomy and ligation. These long-standing rheumatoid patients (suffering for five to 15 years), presented with at least four of the seven 1987 revised criteria of the American College of Rheumatology for diagnosis of rheumatoid arthritis. A 2.5 cm long and 2 cm deep tissue space was dissected and prepared in each transplant recipient at the axilla using diathermy and knife after infiltrating the site with one percent lignocaine solution. The tissue collected from the consenting mother undergoing hysterotomy and ligation was inserted into this site, and the site was closed with 00 atraumatic vicryl. All necessary pre- and postoperative surgical precautions were taken to prevent infections. Sequential total count and differential count of leucocytes were undertaken to analyze the impact of the transplant on the host. After one month, a part of the transplanted fetal tissue was recovered for histological staining to examine whether there was any graft versus host reaction. RESULTS AND ANALYSIS: All ten patients tolerated the transplant procedure well. There was no fever, intractable pain or any other specific serious side-effect which could justify the removal of the transplant before one month. There was no discharge from the incision site and the healing of the scar was by and large normal. There was no unusual leucocytosis, lymphocytosis and the retrieved graft tissue did not suggest transplant rejection. However, there was definite pain relief, reduction in swelling and improvement of mobility of varying degree in a majority of the patients which was perceivable from the 15th day onwards. There was also a sense of well being (in 80%) and a gain in weight of three pounds or more (in 70%) among the fetal transplant recipients. DISCUSSION AND CONCLUSION: To understand the underlying mechanism, in case of pregnancy immunotolerance, we are of the opinion that emphasis should be placed on the role of non-specific and non-cytopathic blocking antibodies produced during pregnancy. The hypo-antigenicity of the developing human fetal system may possibly contribute to the production of this blocking antibody during pregnancy, and thus may play a role in the lack of recognition by the host's HLA system. This behaviour of the developing human fetal tissue provides some advantages over adult tissue for fetal cell/tissue transplantation purposes. The relief of pain, inflammation and restoration of mobility may be due to the effect of the transplanted adrenal graft, with the medullary component contributing to endorphin-like substance liberation and the cortical component contributing to glucocorticoid synthesis.

Adrenal Glands↗
PubMed2002

Can human fetal cortical brain tissue transplant (up to 20 weeks) sustain its metabolic and oxygen requirements in a heterotopic site outside the brain? A study of 12 volunteers with Parkinson's disease.

BACKGROUND: Neural and stem cell transplantation is emerging as a potential treatment for neurodegenerative diseases from Parkinson's to Huntington's disease. Stereotactic placement of dopaminergic neurons in the caudate-putamen (striatum), is being attempted in centers of excellence and has proved to be beneficial. Basic research using cell transplantation indicates that structural development mechanisms seen in immature brains, i.e., fetal brains, can also function in the adult brain. The adult brain consumes 15% of the resting cardiac output for its metabolic needs. While most human tissues can sustain an anaerobic assault for a few minutes up to 30 minutes, a sudden total lack of oxygen supply to the brain cells in an adult will render the person unconscious within five to ten seconds. Our team has been working on the problem of human fetal tissue response to antigenic assault for the last two decades. In the present series, 12 patients with prolonged histories of Parkinsonism, who were not responding to anti-Parkinsonian drugs, and could not afford costly stereotactic surgery or deep brain stimulation and other modalities of recent Parkinson's disease treatment, were enrolled in the study. MATERIALS AND METHOD: After obtaining proper informed consents from the patients or their guardians and from the multidisciplinary ethical committee, the patients, varying in age from 45 to 75 years and suffering for many years with Parkinsonism, were enrolled in the heterotopic brain tissue transplant programme. We followed standard antiseptic, aseptic and premedication protocols, after selecting a proposed site of transplantation of the brain in the axillary fold of the skin, under local infiltration anaesthesia. In an adjacent OR, a fetus was collected from a consenting patient undergoing hysterotomy and ligation (before 20 weeks), under general anaesthesia. Within a minute of hysterotomy, the fetal brain tissue was dissected, and under the guidance of the operative microscope, 1 g of fetal cortical brain tissue was dissected and weighed in an electronic machine. The tissue was collected from around 1 cm of the frontal opercula of the developing human fetal brain and grafted in the already dissected and prepared subcutaneous site in the axilla and the skin was closed. Hematological parameters (Hgb; total count, Tc; differential count, Dc; erythocyte sedimentation rate, ESR) were estimated sequentially up to one month. A small portion of the transplanted tissue was retrieved after one to two months, and a serial histological study was done along with a clinical assessment of the disease condition as per the specifications of the Unified Parkinson's Disease Rating Scale. The results were matched with the pre-transplant ratings of the individual cases. Presenting dyskinesia was also rated (0-4), on the basis of objective criteria assessment like walking, putting on a coat, lifting a cup to drink, etc. RESULTS AND ANALYSIS: Initially 30 patients suffering from advanced Parkinson's disease (PD) were approached after getting the necessary clearance from the institutional multidisciplinary ethical committee; however, we have been able to arrange transplantation in only 12 cases so far. These patients were evaluated at the pre- and one month post-transplant period by the Unified Parkinson's Disease Rating Scale (0-108) and the minimum score was 40 in the motor portion of the unified scale at the pre-transplant state. Evaluation of the patients after one month revealed mild improvement of the pre-transplant scoring (up to 33.3%) in 41.6% of the cases, and moderate improvement (up to 66.6%) in another 41.6% of the cases. While 16.8% of the cases did not show any improvement from the basal score, i.e., the pre-transplant score, there was a definite sense of well being and rise in weight (2-4 pounds) noted in each case and there was also a reduction of the L-Dopa dosage in 75% of the cases. There was also a 58.3% improvement in the bradykinesia scoring from the pre-transplant level. What is intriguing is the survival, growth and proliferation of the grafted fetal brain tissue in the HLA- and sex-randomized adult axilla without any immunosuppressive support. Not a single histological study of the fetal brain tissues after removal from the axilla showed any signs of graft vs. host or inflammatory reaction (Figures 1-9) but there were features of growth of the transplanted cortical brain tissue along with its different components like neurogenesis, gliogenesis, early neovascularisation and angiogenesis, etc. There was also no systemic leucocytosis or lymphocytosis. DISCUSSION AND CONCLUSION: Histological evidence at the transplanted tissue site suggests that fetal cortical brain tissue can sustain life in sex-randomized, HLA-randomized adult hosts, without the support of immuno-suppressive drugs and the tacit support of the blood-CSF and blood-brain barrier and other specific requirements of adult brain cells in the skull. Whether the clinical improvement in PD is transient or long lasting is presently under investigation along with basic questions like, is it due to transplanted fetal dopaminergic or non-dopaminergic neurons or is it the growth factors and the cytokine mediated hitherto unknown reactions causing the clinical improvement.

Aged↗
PubMed2001

Pim-1 negatively regulates the activity of PTP-U2S phosphatase and influences terminal differentiation and apoptosis of monoblastoid leukemia cells.

The levels of Pim-1, a serine/threonine kinase, increase during phorbol myristate acetate (PMA)-induced myeloid cell differentiation. The tyrosine phosphatase PTP-U2S is also associated with PMA-induced differentiation of myeloid cells and has been shown to enhance differentiation and the onset of apoptosis. PTP-U2S contains a Pim-1 phosphorylation consensus sequence, KKRKLTN, which is efficiently phosphorylated by Pim-1. Immunoprecipitated PTP-U2S from U937 cells was phosphorylated by recombinant Pim-1, resulting in a decrease in its phosphatase activity. During PMA-induced differentiation, U937 cells transfected with the dominant negative Pim-1 underwent rapid differentiation and accelerated apoptosis. The opposite effect was observed for wild-type Pim-1. Our results, therefore, provide compelling evidence that Pim-1 functions to negatively regulate PMA-induced differentiation in part through the phosphorylation of PTP-U2S. Together these data suggest that Pim-1 phosphorylates PTP-U2S in vivo to decrease the phosphatase activity that may be necessary to prevent the premature onset of apoptosis following differentiation.

Amino Acid Sequence↗
PubMed2001

Electroencephalographic and perceptual asymmetry differences between responders and nonresponders to an SSRI antidepressant.

BACKGROUND: Recent reports suggest the value of electroencephalographic and dichotic listening measures as predictors of response to antidepressants. This study examines the potential of electroencephalographic alpha asymmetry and dichotic measures of perceptual asymmetry as predictors of clinical response to 12 weeks of treatment with fluoxetine (Prozac). METHODS: Resting electroencephalography (eyes open and eyes closed) and dichotic listening with word or complex tone stimuli were assessed in depressed outpatients during a pretreatment period. RESULTS: Fluoxetine responders (n = 34) differed from nonresponders (n = 19) in favoring left over right hemisphere processing of dichotic stimuli. They also differed in their resting electroencephalographic alpha asymmetry, particularly in the eyes open condition. Nonresponders showed an alpha asymmetry indicative of overall greater activation of the right hemisphere than the left, whereas responders did not. The relationship between hemispheric asymmetry and treatment response interacted with gender, being evident among depressed women but not men. CONCLUSIONS: The results are consistent with the hypothesis that a characteristic tendency toward greater left than right hemisphere activation is associated with favorable response to fluoxetine, whereas the opposite hemispheric asymmetry predicts poor response.

Adolescent↗
PubMed2001

Androgen-driven prostate epithelial cell proliferation and differentiation in vivo involve the regulation of p27.

Androgens control both growth and differentiation of the normal prostate gland. However, the mechanisms by which androgens act upon the cell cycle machinery to regulate these two fundamental processes are largely unknown. The cyclin-dependent kinase (cdk) inhibitor p27 is a negative cell cycle regulator involved in differentiation-associated growth arrest. Here, we investigate the role and regulation of p27 in the testosterone proprionate (TP)-stimulated regeneration of the ventral prostate (VP) of castrated rats. Continuous TP administration to castrated rats triggered epithelial cell proliferation, which peaked at 72 h, and then declined despite further treatment. Castration-induced atrophy of the VP was associated with a significant increase in p27 expression as compared with the VP of intact animals. Twelve hours after the initiation of androgen treatment, total p27 levels as well as its fraction bound to cdk2, its main target, significantly dropped in the VP of castrated rats. Thereafter, concomitantly to the induction of epithelial cell proliferation, the glandular morphology of VP was progressively restored at 48-96 h of TP treatment. During this period of the regenerative process, whereas both proliferating basal and secretory epithelial cells did not express p27, the protein was selectively up-regulated in the nonproliferating secretory epithelial compartment. This up-regulation of p27 expression was coincident with an increase in its association with, and presumably inhibition of, cdk2. At each time point of TP treatment, p27 abundance in the VP was inversely correlated with the level of its proteasome-dependent degradation activity measured in vitro in VP lysates, whereas only slight changes in the amount of p27 transcripts were detected. In addition, the antiandrogen flutamide blocked maximal TP-induced p27 degradation completely. Finally, the expression of skp2, the ubiquitin ligase that targets p27 for degradation, was seen to increase with androgen administration, preceding maximal proliferation and concomitantly to augmented p27 degradation activity. Taken together, our data indicate that androgens mediate both proliferation and differentiation signals in normal prostate epithelial cells in vivo, through regulation of p27.

Androgen Antagonists↗
PubMed2001

A study report of 174 units of placental umbilical cord whole blood transfusion in 62 patients as a rich source of fetal hemoglobin supply in different indications of blood transfusion.

BACKGROUND: In the animal kingdom, even herbivorous animals swallow the placenta after the birth of the baby (for example, the cow). In the human system, we do not know about the proper utilization of the placenta and membranes although there are suggestions regarding this on the basis of research on placental umbilical cord blood stem cells as an alternative to bone marrow transplantation. In this present series of placental umbilical cord whole blood transfusions, we wanted to examine the safety aspect of other components of cord blood transfusion, e.g., fetal RBC, growth factors and cytokine filled plasma, etc., in different indications of blood transfusion, from the pediatric to the geriatric age group, in malignant and non-malignant disorders affecting our patients. METHODS: One hundred and seventy-four units of umbilical cord whole blood were collected aseptically from the umbilical vein after caesarean section in standard pediatric blood transfusion bags, after the removal of the baby from the operative field and after confirming the stable condition of the mother. The volume of cord blood varied from 50 ml to 140 ml with a mean of 86 ml+/-16 ml. RESULTS AND ANALYSIS: The cord blood was transfused immediately (within three days of collection) to 62 patients from nine years to 78 years of age, of whom 32 were suffering from varying stages and grades of malignancy from 1 April 1999 till date i.e., 11 Aug 2000, after obtaining adequate consent and following the precautions of standard blood transfusion protocol. The remaining 30 patients included patients suffering from thalassemia major, aplastic anemia, systemic lupus erythematosus, chronic renal failure, rheumatoid arthritis, ankylosing spondylitis and a geriatric group of patients with benign prostatic hypertrophy. All have tolerated the procedure without any immunological or non-immunological reactions. CONCLUSION: On the basis of our experience with 174 units of placental umbilical cord whole blood transfusion in malignant and non-malignant conditions (within three days of collection and preservation at 1-6 degrees C in a refrigerator), we are of the opinion that this is a safe transfusion protocol which takes advantage of the safety of nature's finest biological sieve, i.e., the placenta, as an alternative to adult whole blood transfusion. It also has the advantage of a higher oxygen carrying capacity of fetal hemoglobin in addition to many growth factors and other cytokine filled cord blood plasma along with its hypoantigenicity.

Adolescent↗
PubMed2001

A unique experience with human pre-immune (12 weeks) and hypo-immune (16 weeks) fetal thymus transplant in a vascular subcutaneous axillary fold in patients with advanced cancer: a report of two cases.

BACKGROUND: The successful development of fetal cell/tissue transplantation in adults has resulted in the possibility of eventual therapeutic solutions with a variety of intractable diseases. Umbilical cord whole blood transplantation appears to be safe in the adult system. In severe forms of DiGeorge Syndrome, cultured thymus transplant can help in the reconstitution of the immune condition of the host. Successful fetal tissue transplant in adults has raised the hope of future effective gene transplant and its manipulation prospects to combat many diseases including hemopathies, inborn errors of metabolism, immunodeficiencies and even cancer and AIDS. MATERIALS AND METHOD: Two cases of advanced cancer were treated with fetal (pre-immune 12 weeks and hypo-immune 16 weeks) thymus transplants in subcutaneous vascular axillary folds, which were removed after one month. Thymuses were collected from consenting mothers undergoing hysterotomy and ligation. RESULTS AND ANALYSIS: Patient I was suffering from non-Hodgkins lymphoma (Ann Arbor Stage IV) and was receiving cyclophosphomide, doxorubicin, vincristine and prednisolone after a course of radiotherapy; she developed leucopenia (2.400/cmm), which improved after receiving a 16-week human fetal thymic graft. The leucopenia was eventually over-corrected and the leucocyte count reached 44,000/cmm within a month, which was reversed after the thymus was taken out. Histology of the excised thymic graft showed growth and proliferation without any graft vs. host (GVH) reaction. Patient 2 was suffering from breast duct carcinoma (T4, N2, M0,) with estrogen, progesterone, and epidermal growth factor negative status, and was treated with modified radical mastectomy and axillary clearance followed by chemotherapy with cyclophosphomide, methotrexate and 5-fluorouracil for six cycles. She also received a 12-week-old human fetal thymus at the contra-lateral axilla which was removed after one month. In this case the peripheral leucocyte count did not show appreciable variation as in the first case. However, histology of the excised thymic graft showed growth and proliferation with an appearance of Hassel's corpuscles. CONCLUSION: Pre-immune and hypo-immune human fetal thymic transplant is not rejected in patients suffering from advanced cancer within one month (observation period). Thymic lymphocyte shedding in the correction of leucopenia in the background of non-Hodgkin's lymphoma may have many therapeutic implications.

Adolescent↗
PubMed2001

Fetal tissue/organ transplant in HLA-randomized adult vascular subcutaneous axillary folds: preliminary report of 14 patients.

BACKGROUND: In the year 1902, the first successful experimental organ transplant, i.e., an autotransplant of a dog's kidney from its normal position to the vessels of the neck, which resulted in some urine flow, was performed in the Vienna Physiology Institute under the direction of Hofrath Exner by Dr. Emerich Ullman (1861-1937). Since then, the art of transplant surgery has come a long way in establishing itself as an important discipline with the support disciplines of immunology, molecular biology, etc., for the restoration of a failing organ. Today there is a major discrepancy in the demand and supply of organ grafts. The aim of the present study is to see whether fetal organ and tissue, with its intrinsic advantages of hypo-antigenicity, can survive in a HLA and sex-randomized host in a surgically prepared vascular subcutaneous axillary fold, without any immunosuppressive support. We have earlier reported two cases of fetal thymic transplant, collected from consenting mothers undergoing hysterotomy and ligation. MATERIALS AND METHODS: Fourteen cases were recruited for the present study after thorough informed consent and approval by the Ethical Committee of the Project. Of these, five patients were suffering from advanced cancer, three from diabetic gangrene, three from ischaemic heart disease and three from rheumatoid arthritis, liver abscess and disc prolapse. The ages of the patients varied from 39 to 82 years. Six fetal thymuses, three fetal liver tissues, three fetal cardiac tissues, one fetal pancreas and one fetal lung tissue were transplanted. All the fetuses were dissected and the selected tissues/organs were transplanted within one to three minutes after collecting them from the consenting mothers undergoing hysterotomy and ligation. The fetal tissue graft was placed in a surgically prepared subcutaneous vascular axillary fold, 2x1 cm, under local anaesthesia in the consenting adult recipient. Sequential Hb, Tc, Dc, ESR were done to see the impact of the transplant on the host system. After one month, the transplanted fetal tissue was taken out by an elliptical incision and the tissue was processed for histological staining. RESULTS AND ANALYSIS: All the 14 patients tolerated the transplant procedure well. There was no fever, intractable pain or any other specific serious side-effect justifying removal of the transplant earlier. There was no discharge from the incision site and the healing and scar were by and large normal. There was no unusual leucocytosis or lymphocytosis. The serial histological study did not suggest features of transplant rejection. DISCUSSION AND CONCLUSION: Pregnancy and neoplasm are two outstanding examples of natural tolerance to homograft. In both cases, blocking antibody has an important role in the phenomenon of immunotolerance. From our experiments mentioned above transplantation and our earlier reported studies, we believe that the hypo-antigenic fetal tissue has distinct advantages over adult tissue for transplant purposes.

Adult↗
PubMed2001

Pim-1: a serine/threonine kinase with a role in cell survival, proliferation, differentiation and tumorigenesis.

Pim-1 belongs to a family of serine/threonine protein kinases that are highly conserved through evolution in multicellular organisms. Originally identified from moloney murine leukemia virus (MuLV)-induced T-cell lymphomas in mice, Pim-1 kinase is involved in the control of cell growth, differentiation and apoptosis. Expression of Pim-1 kinase can be stimulated by a variety of growth factors and regulated at four different levels: transcriptional, post-transcriptional, translational and post-translational. Several signal transduction pathways may be associated with the regulation of Pim-1's expression; accumulating data support that the expression of Pim-1 protein is mediated through activation of JAK/STATs. Recent studies of Pim family kinases indicate that Pim-1 kinase plays important roles outside of the hematopoietic system as well.

Animals↗
PubMed2000

Reduction of Cdc25A contributes to cyclin E1-Cdk2 inhibition at senescence in human mammary epithelial cells.

Replicative senescence may be an important tumor suppressive mechanism for human cells. We investigated the mechanism of cell cycle arrest at senescence in human mammary epithelial cells (HMECs) that have undergone a period of 'self-selection', and as a consequence exhibit diminished p16INK4A levels. As HMECs approached senescence, the proportion of cells with a 2N DNA content increased and that in S phase decreased progressively. Cyclin D1-cdk4, cyclin E-cdk2 and cyclin A-cdk2 activities were not abruptly inhibited, but rather diminished steadily with increasing population age. In contrast to observations in fibroblast, p21Cip1 was not increased at senescence in HMECs. There was no increase in p27Kip1 levels nor in KIP association with targets cdks. While p15INK4B and its binding to both cdk4 and cdk6 increased with increasing passage, some cyclin D1-bound cdk4 and cdk6 persisted in senescent cells, whose inhibition could not be attributed to p15INK4B. The inhibition of cyclin E-cdk2 in senescent HMECs was accompanied by increased inhibitory phosphorylation of cdk2, in association with a progressive loss of Cdc25A. Recombinant Cdc25A strongly reactivated cyclin E-cdk2 from senescent HMECs suggesting that reduction of Cdc25A contributes to cyclin E-cdk2 inhibition and G1 arrest at senescence. Although ectopic expression of Cdc25A failed to extend the lifespan of HMECs, the exogenous Cdc25A appeared to lack activity in these cells, since it neither shortened the G1-to-S phase interval nor activated cyclin E-cdk2. In contrast, in the breast cancer-derived MCF-7 line, Cdc25A overexpression increased both cyclin E-cdk2 activity and the S phase fraction. Thus, mechanisms leading to HMEC immortalization may involve not only the re-induction of Cdc25A expression, but also activation of this phosphatase.

Adult↗
PubMed2000

Down-regulation of p21WAF1/CIP1 or p27Kip1 abrogates antiestrogen-mediated cell cycle arrest in human breast cancer cells.

Estrogens and antiestrogens influence the G(1) phase of the cell cycle. In MCF-7 breast cancer cells, estrogen stimulated cell cycle progression through loss of the kinase inhibitor proteins (KIPs) p27 and p21 and through G(1) cyclin-dependent kinase (cdk) activation. Treatment with antiestrogen drugs, Tamoxifen or ICI 182780, caused cell cycle arrest, with up-regulation of both p21 and p27 levels, an increase in their binding to cyclin E-cdk2, and kinase inhibition. The requirement for these KIPs in the arrests induced by estradiol depletion or by antiestrogens was investigated with antisense. Antisense inhibition of p21 or p27 expression in estradiol-depleted or antiestrogenarrested MCF-7 led to abrogation of cell cycle arrest, with loss of cyclin E-associated KIPs, activation of cyclin E-cdk2, and S phase entrance. These data demonstrate that depletion of either p21 or p27 can mimic estrogen-stimulated cell cycle activation and indicate that both of these KIPs are critical mediators of the therapeutic effects of antiestrogens in breast cancer.

Base Sequence↗
PubMed2000

Involvement of p27Kip1 in G1 arrest by high dose 5 alpha-dihydrotestosterone in LNCaP human prostate cancer cells.

The cell cycle is governed by cyclin dependent kinases (cdks), which are activated by binding of cyclins, inhibited by cdk inhibitors and regulated by phosphorylation and dephosphorylation. Exposure to high dose dihydrotestosterone (DHT) inhibits population growth of the human prostate carcinoma cell line, LNCaP. To determine the mechanism of growth arrest by high dose DHT, we assayed the changes in cell cycle profile and the cell cycle regulators that mediate these effects. Treatment of asynchronously growing LNCaP cells with 100 nM DHT caused a G1 arrest. The proportion of cells in S phase fell from 22 to 2%, while the G1 fraction rose from 74 to 92% by 24 h. Loss of phosphorylation of the retinoblastoma protein was noted and cdk4 and cyclin E/ cdk2 activities fell. Inhibition of these G1 cyclin dependent kinases was not due to loss of either cyclin or cdk proteins nor to increases in the cdk inhibitors p16INK4A and p21CiP1. p21Cip1 protein levels remained constant, and cyclin E-associated p21CiP1 fell, suggesting that p21CiP1 is not relevant to this form of cyclin E/cdk2 inhibition. Of note, total p27KiP1 levels and cyclin E-associated p27Kip1 increased as cells arrested and the amount of the CAK activated cdk2 bound to cyclin E decreased. p27KiP1 immunodepletion experiments demonstrated that the DHT-mediated increase in p27Kip1 was sufficient to fully saturate and inhibit target cyclin E/ cdk2. The inhibition of cyclin E/cdk2 by p27Kip1 contributes to G1 arrest of LNCaP following high dose DHT. p27KiP1 may be a key effector of androgen dependent growth modulation in prostate cancer cells.

CDC2-CDC28 Kinases↗
PubMed1999

Reduced expression of the cell cycle inhibitor p27Kip1 in non-small cell lung carcinoma: a prognostic factor independent of Ras.

Levels of p27 have been found to have independent prognostic significance in a variety of tumors including breast, colon, prostate, ovary, and gastric carcinomas. We investigated p27 levels and determined ras mutational status in 136 non-small cell lung cancers. We found reduced levels of p27 in 86% of cases and showed a statistically significant inverse correlation between p27 levels and tumor grade. ras mutations were found exclusively in adenocarcinomas and showed no relationship to p27 levels. Clinical data on a subset of the patients studied indicated that all 16 patients who died of disease and 21 of 22 patients who relapsed had low p27 levels, whereas all patients with high p27 levels were alive at last follow up. These findings suggest that alteration in p27 levels plays an important role in lung tumor progression and that p27 levels may have independent prognostic significance in non-small cell lung cancer.

Carcinoma, Non-Small-Cell Lung↗
PubMed1999

Interleukin-6 dependent induction of the cyclin dependent kinase inhibitor p21WAF1/CIP1 is lost during progression of human malignant melanoma.

Human melanoma cell lines derived from early stage primary tumors are particularly sensitive to growth arrest induced by interleukin-6 (IL-6). This response is lost in cell lines derived from advanced lesions, a phenomenon which may contribute to tumor aggressiveness. We sought to determine whether resistance to growth inhibition by IL-6 can be explained by oncogenic alterations in cell cycle regulators or relevant components of intracellular signaling. Our results show that IL-6 treatment of early stage melanoma cell lines caused G1 arrest, which could not be explained by changes in levels of G1 cyclins (D1, E), cdks (cdk4, cdk2) or by loss of cyclin/cdk complex formation. Instead, IL-6 caused a marked induction of the cdk inhibitor p21WAF1/CIP1 in three different IL-6 sensitive cell lines, two of which also showed a marked accumulation of the cdk inhibitor p27Kip1. In contrast, IL-6 failed to induce p21WAF1/CIP1 transcript and did not increase p21WAF1/CIP1 or p27kip1 proteins in any of the resistant lines. In fact, of five IL-6 resistant cell lines, only two expressed detectable levels of p21WAF1/CIP1 mRNA and protein, while in three other lines, p21WAF1/CIP1 was undetectable. IL-6 dependent upregulation of p21WAF1/CIP1 was associated with binding of both STAT3 and STAT1 to the p21WAF1/CIP1 promoter. Surprisingly, however, IL-6 stimulated STAT binding to this promoter in both sensitive and resistant cell lines (with one exception), suggesting that gross deregulation of this event is not the unifying cause of the defect in p21WAF1/CIP1 induction in IL-6 resistant cells. In somatic cell hybrids of IL-6 sensitive and resistant cell lines, the resistant phenotype was dominant and IL-6 failed to induce p21WAF1/CIP1. Thus, our results suggest that in early stage human melanoma cells, IL-6 induced growth inhibition involves induction of p21WAF1/CIP1 which is lost in the course of tumor progression presumably as a result of a dominant oncogenic event.

Cell Cycle Proteins↗