Biomedical subjects

M R Pillai

Publications and source records attributed to M R Pillai.

At least 55 records · Page 3Linked to original sources

PubMed1997

p53 tumor suppressor protein and tissue proliferative fraction in infiltrating duct carcinoma.

BACKGROUND AND OBJECTIVES: Breast cancer continues to frustrate oncologists worldwide. In India, it is the second most common neoplasm among women and is increasing in incidence. Several molecular markers have been associated with a poor prognosis in patients with breast cancer, and the presence of these markers is often thought to provide information on the biological behavior of the malignant breast tumor. Much attention has recently been focused on the tumor suppressor gene p53. Mutation or alteration in this gene leads to the loss of negative growth regulation and hence to rapid cell proliferation. The present study was designed to evaluate the connection between expression of the p53 protein and its relation to the tissue proliferative compartment as measured by expression of the proliferating cell nuclear antigen (PCNA). METHODS: Expression of p53 and PCNA were detected by immunocytochemistry in paraffin-embedded sections of infiltrating duct carcinoma and control breast tissue (normal tissue and adenoma). RESULTS: A significant correlation was observed between expression of p53 and PCNA. A significant correlation was also observed between expression of p53 and grade of tumor and stage of disease. CONCLUSIONS: Our results support the hypothesis that accumulation of p53 is associated with a high tumor proliferation rate an association that might be expected in view of the role of wild p53 as a negative regulator of cell proliferation.

Adenoma↗

PubMed1997

Increased expression of cytokeratins 14, 18 and 19 correlates with tumor progression in the uterine cervix.

The expression of cytokeratins (CKs) in normal cervical epithelium, low grade squamous intraepithelial lesions (SIL), high grade SILs and squamous cell carcinoma (SCC) were analyzed using four different monoclonal antikeratin antibodies. In normal cervical epithelium, CK 18 showed strong immunoreactivity in basal and parabasal layers. CK 19 and 14 were expressed only in the basal layer while CK 13 was found selectively n the spinal cells. As the lesions progressed from low grade SIL to high grade SIL, immunoreactivity of CK 18, 19 and 14 in the basal cell compartment increased while the expression of CK 13 decreased. In SCC, as well-differentiated tumors showed decreased immunoreactivity for CK 18, 19 and 14 with CK 13 showing a strong and focal (localized) immunoreactivity. Undifferentiated carcinomas totally lacked CK 13 reactivity. Our findings therefore suggest that expression of CK 18, 19 and 14 may be directly related to tumor grade and CK 13 may be a marker of differentiation in cervical lesions.

Adenocarcinoma↗

PubMed1997

Expression of the antiapoptotic protein bcl-2 is not dependent on the tumor suppressor p53 protein in Indian breast carcinoma.

Tissue homeostasis and the maintenance of cell populations depend on a delicate balance between the rates of cell proliferation and cell death. Programmed cell death or apoptosis is believed to play a major role in physiological processes which, when defective, could contribute to the pathogenesis and progression of tumors. A role for altered programmed cell death in cancer stems from the description of alterations on tumor-associated genes involved in the regulation of apoptosis such as p53 and bcl-2. The p53 gene promotes apoptosis in cells with genetic damage, while bcl-2 is an antiapoptotic gene. It is therefore possible that the balance between p53 and bcl-2 may have significant implications for the pathobiology of breast cancer. This study was therefore undertaken to evaluate the expression of these two proteins with opposite functions and their relation to the total growth fraction of the tumor as measured by PCNA immunoreactivity. A significant correlation was observed between expression of p53 and PCNA. In contrast, bcl-2 expression did not correlate with the expression of p53. There was also no correlation observed between expression of bcl-2 and PCNA. A significant correlation was observed between expression of p53 and the grade of the tumor and stage of the disease. Our results thus support the hypothesis that accumulation of p53 is associated with a high tumor proliferation rate, an association that might be expected in view of the role of wild-type p53 as a negative regulator of cell proliferation. Another important observation was the lack of relationship between bcl-2 expression and PCNA immunoreactivity, supporting the hypothesis that bcl-2 is not a major regulator of proliferation.

Apoptosis↗

PubMed1997

c-erbB-2 oncoprotein and epidermal growth factor receptor in cervical lesions.

Epidermal growth factor receptor (EGF-R) and the oncogene product of c-erbB-2 have been shown to be expressed in human tumors and in some cases relate to clinical outcome. This study investigates the correlation between the presence of these receptor proteins and various histological grades of cervical tissues. Immunocytochemical analysis of benign, premalignant and malignant cervical tissues showed a highly significant correlation between the expression of the two proteins and the histological grade of the lesions. Moreover, the overall frequency of coexpression of these proteins was similar. This study suggests that these proteins may be involved in cellular proliferation and have a significant role in the progression of cervical cancer.

Carcinoma in Situ↗

PubMed1997

Chemoprevention of oral cancer: the need for effective biological monitoring.

A major limiting factor in the successful implementation of chemoprevention for oral cancer has been the lack of suitable endpoints to measure efficacy and success of clinical trials. To depend on the measure of the ultimate goal of such trials, namely cancer incidence as an endpoint has serious feasibility problems including a need for large numbers of participants, long periods of follow up and high costs. The application of selected biological markers as intermediate endpoints to reveal responses to chemopreventive regimens within a limited time frame is therefore an attractive concept. By serving as surrogates for cancer they could become valuable tools for monitoring patient compliance, defining the process of carcinogenesis and evaluating effects of the chemopreventive agents on tumour progression. This paper examines various biological markers of oral carcinogenesis and their relevance to chemoprevention trials. If validated, these biological markers could take oral cancer chemoprevention to new frontiers and help fulfil the ultimate goal of disease prevention through intervention.

Biomarkers, Tumor↗

PubMed1997

p53 protein and tumorigenesis in the uterine cervix.

The relationship between molecular abnormalities of p53 tumor suppressor gene product and cancer has been well documented. That correlation may exist between immunocytochemically detectable amount of p53 protein and neoplasia is evidenced by several studies. Detection of p53 protein by immunocytochemistry varies depending on the methods and antibodies used. It has been suggested that the quantitative aspect of p53 protein expression and the proportion of cells expressing p53 may be of clinical importance in human malignancies. In the present study, we have examined the expression of p53 protein in various grades of lesions of the uterine cervix. Statistical analysis showed a good correlation between expression of p53 protein and histologic grade of lesions. Increased expression of p53 in dysplastic and malignant lesions compared to non dysplastic lesions suggests that p53 protein accumulation may be an early event in carcinogenesis.

Cell Nucleus↗

PubMed1997

The basement membrane and tumor progression in the uterine cervix.

Immunocytochemical localization of the basement membrane (BM) proteins laminin, type-IV collagen and fibronectin were analyzed in normal cervical epithelium, low grade squamous intraepithelial lesions (SILs), high grade SILs and invasive squamous cell carcinoma (SCC) of the uterine cervix. A regular, thick and continuous BM was present in normal cervical epithelium and low grade SIL. Interruptions and discontinuity of the BM were more evident in high grade SILs. There was a good correlation between increasing severity of the lesion and increasing number of breaks. In SCC, the distribution of laminin, collagen IV and fibronectin was related to the degree of cellular differentiation, with decreased immunoreactivity being evident in moderately and poorly differentiated tumors. As the invasive potential of the tumor increased, the fragmentation and loss of BM was more evident. Fibronectin showed only moderate to mild immunoreactivity in normal cervical epithelium and low grade SILs. However, the intensity of expression increased in high grade SILs especially in the peritumoral stroma. It may therefore be concluded from these results that snythesis and reabsorption of BM proteins may be related to shifts in cellular metabolism during tumorigenesis.

Basement Membrane↗

PubMed1997

Cytokeratins and the evaluation of tumor differentiation in squamous lesions of the uterine cervix.

The differential expression of cytokeratins in epithelial or squamous cells has been demonstrated to be altered during the process of carcinogenesis. This altered expression of cytokeratins (CKs) may be closely related with epithelial differentiation and may remain stable in malignant tumors. In the present study an analysis using two monoclonal antibodies, CK 8.12 antibody specific for CK type 13 and 16 and CK 8.60 antibody specific for CK type 1, 10 and 11 was done in different grades of lesions in the uterine cervix. Changes from the normal expression pattern were seen in high grade Squamous intraepithelial lesions (SIL) (CIN-2/3) and invasive squamous cell carcinoma (SCC). No conspicuous difference in the staining expression between normal/benign cervical tissue and low grade SIL (CIN-I) was evident. Statistical analysis also revealed a significant correlation between the expression of these CK types to the differentiation status of the cervical lesions analyzed. Alterations in the expression of these CKs can be correlated to the differentiation pathway which may be deregulated during cervical carcinogenesis. The findings of the present study suggest that the expression of CK types 13 and 16 and 1, 10 and 11 using CK 8.12 and CK 8.60 antibodies respectively may serve as markers of differentiation in cervical squamous neoplasms.

Adult↗

PubMed1997

Tumor proliferative fraction in infiltrating duct carcinoma.

Deregulated cell proliferation is a key factor in malignancy and therefore may be of prognostic significance. Both Proliferating Cell Nuclear Antigen (PCNA) and silver binding Argyrophilic Nucleolar Organizer Regions (AgNORs) have been established as a valuable reflection of the tissue proliferative compartment and hence could be of value in studying the biologic behavior of malignant cells. In the present study, we evaluated the proliferative activity of 120 infiltrating duct carcinomas by analysing for PCNA and AgNOR expression in relation to pathologic variables. The AgNOR scores were significantly greater in the malignant tissue than in benign lesions. Expression of PCNA was also found to be increased in malignant breast tumors, when compared to controls. A strong positive correlation between PCNA immunoreactivity and AgNORs was evident. There was also a positive correlation between histologic grading and AgNOR score in breast cancer (r = 0.92, p = 0.000). Tumor with elevated AgNOR counts were often poorly differentiated. It is therefore apparent that evaluation of AgNORs and PCNA may help in the elaboration of histopathologic grading of infiltrating duct carcinoma and may be of prognostic significance.

Breast Neoplasms↗

PubMed1997

Characteristics of a 60K gelatinase involved in rat mammary gland involution.

In order to study the role of matrix degrading enzymes in modulating cell matrix interaction, an understanding of the characteristics and regulation of their activity is useful. A number of matrix degrading metalloproteinases are involved in modulating the cell-ECM interactions during the involutory phase of mammary gland resulting in its remodelling. Zymographic studies showed that three types of gelatinases (60K, 68K and 130K) occur during the different phases of involution. The 60K gelatinase which appeared on the fifth day of involution has been purified by affinity chromatography over gelatin sepharose. Zymographic and radiolabelled substrate digestion studies at different pH and in presence of different cations showed that the activated form of this gelatinase is a Ca2+ dependent neutral matrix metalloproteinase capable of cleaving collagen I and collagen IV. Immunocytochemical studies showed that the enzyme is localised at pericellular/extracellular sites.

Animals↗

PubMed1996

Argyrophilic nuclear organizer regions (AgNORs) in pediatric acute lymphoblastic leukemia.

Nuclear organizer regions (NORs) code for ribosomal RNA and are associated with non-histone nucleoproteins which can be identified by silver staining (AgNORs). AgNORs have been correlated to proliferative activity of tumors and hence may be prognosis-related. The present study evaluates the possible prognostic importance of the AgNORs in tumor cells of patients with pediatric acute lymphoblastic leukemia (ALL). A significant increase in AgNOR counts was observed in ALL patients as compared to normal controls. Further, a significant positive correlation was observed between AgNOR counts and total WBC count at diagnosis. A negative correlation was also observed between AgNOR counts and age of the patients. Logistic regression analysis revealed further correlation between AgNOR counts and disease with an odds ratio of 1.29 (P = 0.03) as compared to normal controls. These results therefore suggest that AgNOR counts may be significant in the evaluation of pediatric ALL.

Case-Control Studies↗

PubMed1996

Expression of programmed cell death regulatory p53 and bcl-2 proteins in oral lesions.

With the ultimate goal of characterizing the molecular pathogenesis of oral cancer, the most predominant malignancy in India, immunocytochemical evaluation of p53 and bcl-2 proteins was carried out in hypeplastic oral mucosa, dysplastic oral mucosa and invasive oral cancer. All subjects gave a similar and almost uniform history of prolonged use of betal quid and tobacco. Expression of p53 was insignificant while bcl-2 was absent in hyperplastic leukoplakia lesions. Both proteins were however expressed in leukoplakia with apparent dysplasia. Almost all invasive cancer lesions showed high levels of both p53 and bcl-2. Good correlation was therefore evident between expression of these two proteins and increasing histologic abnormality. Moreover relative risk evaluation revealed that lesions expressing p53 and bcl-2 had a high probability of having a histology of dysplasia or worse. Since it has been previously shown that wild type p53 regulates the expression of bcl-2, it may be presumed that the protein detected in the dysplastic and malignant oral tissue is of the mutant type. It is also known that p53 is a positive regulator of programmed cell death or apoptosis while bcl-2 is an anti-apoptotic protein. This suggests the possibility that alterations in p53 followed by over-expression of bcl-2 occur early in oral carcinogenesis resulting in defective apoptosis and subsequent tumor progression.

Cell Count↗

PubMed1996

Ultrastructural analysis of the adjacent epithelium of oral squamous cell carcinoma.

Fifteen biopsies of the immediate adjacent epithelium of oral squamous cell carcinoma were examined under light and electron microscopy. Light microscopic examination of one micron thick sections revealed that the majority of lesions (67%) had hyperplastic or mildly dysplastic epithelium while the remaining (33%) had moderate to severe dysplasia. Ultrastructural observations showed that all these lesions had subcellular alterations similar to those seen in frank malignant oral tissue, particularly in the lower half of the epithelium. Important ultrastructural changes observed included bizarre nuclei of basal and lower spinal cells, enlarged and multiple nucleoli, presence of interchromatin and perichromatin granules, loss of desmosomes and marked spongiosis as well as disturbed cellular maturation sequences in the keratinocytes evidenced by abnormal and irregular distribution of maturation markers such as keratohyalin granules and tonofilaments. The present study thus shows the value of electron microscopy in the detection of malignant changes in the adjacent epithelium of oral squamous cell carcinoma.

Carcinoma, Squamous Cell↗

PubMed1996

Involucrin and tumor progression in the uterine cervix.

The expression of involucrin, a cytoplasmic protein synthesized during squamous maturation, was assessed by immunocytochemistry in different grades of cervical lesions. In normal/benign cervical epithelium and low-grade squamous intraepithelial lesions [SILS or cervical intraepithelial neoplasia (CIN)-1] involucrin showed intense and homogenous cytoplasmic expression in the spinal layers of 75 and 57% of samples, respectively. The basal cell layers showed no expression of involucrin. In high-grade SILs (CIN-2/3) 40% of the samples showed diffuse and focal cytoplasmic expression of involucrin in the differentiated basaloid cells. In the squamous cell carcinomas (SCCs) analyzed, well-differentiated tumors showed intense focal expression in 61% of the cases, moderately differentiated SCCs showed intense expression in 33% of the cases, while poorly differentiated SCCs (PDSCC) showed only a mild focal expression in 7% of cases. With increasing severity of the lesions, patchy expression of involucrin with a mixture of reactive and nonreactive cells predominated. Patterns of immunocytochemical staining for involucrin in cervical lesions of different grades, from low-grade to high-grade SILs, and invasive carcinoma may be of critical importance, if loss of involucrin expression is used as a criterion for neoplastic transformation in cervical epithelium. Our findings suggest that involucrin may be a sensitive marker in identifying the differentiation status of the lesion while the absence of involucrin in PDSCC may be helpful in differential diagnosis.

Adult↗

PubMed1996

The presence of human papillomavirus-16/-18 E6, p53, and Bcl-2 protein in cervicovaginal smears from patients with invasive cervical cancer.

Cervical cancer is the second leading cause of death from cancer in women worldwide, and recent epidemiological studies have strongly implicated the sexually transmitted human papillomavirus (HPV) as a causative agent. The ability of high-risk HPVs to contribute to malignant progression seems to depend on expression of the viral E6 and E7 oncogenes. The E6 oncoprotein forms a complex with the cellular tumor suppressor protein p53, leading to degradation of p53 via ubiquitin-dependent proteolysis. Thus, E6 expression results in the loss of p53 function in cells, including stimulation of apoptosis and inhibition of the expression of the antiapoptotic protein bcl-2. Recently, we found increased bcl-2 expression in cervical carcinoma cell lines containing mutated or E6-inactivated p53 (X. L. Liang, S. Mungal, A. Ayscue, J. D. Meissner, P. Wodnicki, G. Gordon, S. Lockett, and B. Herman. J. Cell. Biochem., 57: 509-520, 1995). Based on these findings, we examined Papanicolaou smears from 94 women with varying degrees of cervical disease for the presence or absence of p53, HPV-16/18 E6, and bcl-2 proteins using immunofluorescence microscopy. Our findings indicate that there is a statistically significant, inverse association between the presence of p53 and invasive cervical disease [odds ratio (OR), 0.3; 95% confidence interval (CI), 0.1-0.7]. Moreover, the odds of being diagnosed with an invasive stage of cervical cancer were 3.7 times higher (95% CI, 1.6-8.8) for women positive for the E6 protein and 17 times higher (95% CI, 5.5-58.3) for women positive for the bcl-2 protein compared with women negative for E6 and bcl-2. Women with invasive cervical cancer were also 4.59 times more likely to test positive for the presence of more than one marker (95% CI, 1.8-11.8). Chi(2) analysis demonstrated a strong association between the presence of E6 and bcl-2 (P < 0.001) as well as between the presence of E6 of bcl-2 and diagnosis (P = 0.015 and < 0.001, respectively). In the multivariate analysis, the presence of bcl-2 (OR, 18.8; 95% CI, 5.5-67.8) and age at diagnosis (> or = 50 years; OR, 7.8; 95% CI, 2.5-24.5) showed significant association with Invasive cervical disease. These findings indicate that: (a) the presence of the bcl-2 protein is strongly associated with the development of invasive cervical disease: (b) the pattern of the presence of high-risk HPV-E6, p53, and bcl-2 proteins may be useful for identifying women at increased risk for the development of invasive cervical cancer; and (c) a defect in apoptosis may partially underlie the development of cervical cancer.

Adult↗

PubMed1994

Expression of galactoside-specific endogenous lectins and their ligands in human oral squamous cell carcinoma.

Human endogenous lectins have a wide spectrum of biological functions. The present study analyses the expression of beta-galactoside specific and N-acetyl-D-galactosamine specific endogenous lectins in oral squamous cell carcinomas using biotinylated neoglycoproteins. The expression pattern of beta-galactosyl-containing glycoconjugates or ligands of beta-galactoside specific lectins in these tissues was also studied using an endogenous biotinylated lectin, the human 14-kDa lectin. For comparison a galactoside specific plant lectin from mistletoe, Viscum album was also employed. The results demonstrate that oral squamous cell carcinomas mainly express accessible binding sites for lactosylated neoglycoprotein (90%) while few carcinomas expressed mild amount of N-acetyl-D-galactosamine specific binding sites (40%). There was no difference in the binding patterns of these probes between well and less differentiated carcinomas. Expression of these neoglycoprotein binding sites were mostly concentrated in immature basaloid cells, indicating a possible association with cell proliferation. The binding pattern of D-galactosyl specific lectins (human 14-kDa and mistletoe lectins) showed conspicuous differences. This feature emphasizes the caution that needs to be exercised in interpreting the biological significance of results attained using plant lectins on human tissue.

Acetylgalactosamine↗

PubMed1994

Ultrastructure of oral squamous cell carcinoma: a comparative analysis of different histological types.

Twenty-five oral carcinomas and five normal oral epithelial specimens were studied using light and electron microscopy. All histological types (well differentiated squamous cell carcinoma, moderately differentiated squamous cell carcinoma, poorly differentiated squamous cell carcinoma, verrucous carcinoma and spindle cell carcinoma) were seen in the study sample. In addition, 1 case of carcinoma in situ was also present. The normal oral epithelium consisted of three keratinising types (gingiva) and two non-keratinising types (buccal mucosa). The ultrastructural features of oral carcinomas showed good correlation with the features seen in light microscopy. The differentiation status of the lesions showed a relationship with cell and nuclear size, tonofilament and keratin content as well as few other cellular abnormalities. It was also observed that the fine details revealed by electron microscopy were often a means of explaining the characteristic histopathological features of oral carcinoma.

Biopsy↗

PubMed1994

Some observations on the instability of 99mTc-complexes of propylene amine oxime (PnAO).

When eluates from expired 99mMo/99mTc generators were used to form the neutral lipophilic complexes of PnAO and its derivatives, degradation of these chelates occurred on standing to form secondary 99mTc-species. It was determined that the conversion of the primary complexes to secondary complexes was due to the impurities present in the 99mTcO4- eluate. The stability was found to be improved by extraction of the complexes into CHCl3 and reconstituting in buffer after evaporation of CHCl3, indicating that the impurities are non extractable into CHCl3. Purification of the 99mTcO4- eluate from the generator by MEK extraction and its use for the preparation of the PnAO complex produced products which showed practically no degradation for a 6 h period of storage. All the secondary 99mTc complexes of PnAO are converted back to primary complex, when the solution was heated in a boiling water bath for 10-20 min.

Butanones↗