Ras and C-Myc Oncoproteins during Tumor Progression in the Uterine Cervix

Aims and background

Altered oncogenic activity is a feature associated with many malignant and premalignant conditions. Among the many oncogenes, ras and myc are commonly altered in many tumors. This study aims to evaluate the expression of ras and c-myc oncoproteins in a total of 204 cervical tissue samples, including premalignant and malignant lesions as well as apparently normal cervical tissue.

Methods and study design

Mouse monoclonal antibodies against the three mammalian ras gene products (c-H-ras, c-K-ras, c-N-ras) and the c-myc protein were used to evaluate oncoprotein expression by immunocytochemistry.

Results

None of the samples analyzed displayed immunoreactivity for H-ras and K-ras. Normal cervical epithelium showed minimal immunoreactivity for N-ras with about 33% of the samples expressing the protein. More conspicuous expression in normal tissue was displayed by c-myc, with about 90% of the samples expressing the protein (mean value of cells positive = 34%). The immunoreactivity for N-ras increased with increasing histological abnormality from low-grade squamous intraepithelial lesions (SIL) to invasive carcinoma. Increased immunoreactivity for N-ras was evident in the basaloid cells of malignant lesions, with the maximum value of 66% found in poorly differentiated squamous cell carcinoma (PDSCC). The percentage of nuclei positive for c-myc also showed a gradual increase from low-grade SIL onwards, the highest positivity being found in PDSCC, where the mean value was 85%. Statistical analysis revealed a good correlation between the expression of N-ras (r = 0.8922, P = 0.001) and c-myc (r = 0.8856, P =0.001) and various histological stages of tumor progression in the cervical epithelium.

Conclusions

These results therefore suggest that c-myc and N-ras oncoproteins are important during tumor progression in the uterine cervix.

Cytoplasmic translocation of MTA1 coregulator promotes de-repression of SGK1 transcription in hypoxic cancer cells

Chromatin remodeling factor metastatic tumor protein 1 (MTA1), one of the most upregulated oncogene in human cancer, has an important role in gene expression, cell survival and promoting hypoxic response. Successful cancer progression is dependent on the ability of cells to utilize its survival pathways for adapting to hypoxic microenvironment. Although MTA1 is a stress-responsive gene, but whether hypoxia modulates its function and its role in engaging other core stress-responsive survival pathway(s) remains unknown. Here we have discovered that MTA1 is a novel corepressor of serum and glucocorticoid-inducible kinase 1 (SGK1). Surprisingly, this regulatory corepressive function of MTA1 is lost under hypoxia, allowing upregulation of SGK1 expression and engaging the MTA1-SGK1 axis for the benefit of the cell survival. The underlying mechanism of the noticed stimulation of SGK1 expression by hypoxia includes de-repression of SGK1 transcription because of hypoxia-triggered nucleus-to-cytoplasmic translocation of MTA1. In addition, the newly recognized cytoplasmic translocation of MTA1 was dependent on the chaperoning function of heat shock protein 90 (HSP90) and co-accompanied by the formation of MTA1, HSP90 and HIF1α complex under hypoxic condition but not under normoxic condition. Hypoxia-triggered redistribution of MTA1, SGK1 upregulation and cell survival functions were compromised by a pharmacological SGK1 inhibitor. In summary, for the first time, we report MTA1 regulation of SGK1 expression, hypoxia-dependent MTA1 translocation to the cytoplasm and de-repression of SGK1 transcription. These findings illustrate how cancer cells utilize a chromatin remodeling factor to engage a core survival pathway to support its cancerous phenotypes, and reveal new facets of MTA1-SGK1 axis by a physiologic signal in cancer progression.

Synthesis and biological evaluation of 177Lu-DOTA-porphyrin conjugate: a potential agent for targeted tumor radiotherapy detection

A novel unsymmetrically substituted water soluble porphyrin derivative namely, 5-(p-amino-propylene--oxyphenyl)-10,15,20-tris-(p-carboxy-methyl-ene-oxyphenyl)porphyrin was synthesized and coupled with a bifunctional chelating agent, viz. p-NCS-benzyl-DOTA (p-isothiocyanatobenzyl-1,4,7,10-tetra-aza-cyclodo-decane-1,4,7,10-tetra-acetic acid) for developing a suitable conjugate for use in targeted tumor therapy. The porphyrin-p-NCS-benzyl-DOTA conjugate was radiolabeled with 177Lu in good radiolabeling yield. Biodistribution studies performed in Swiss mice bearing fibrosarcoma tumors revealed high tumor uptake (5.33±1.11% injected activity per gm of tumor) within 30 min post-injection. The complex exhibited favorable tumor to blood and tumor to muscle ratios at various post-administration time points. Fast clearance of the non-accumulated activity was observed mostly through the renal pathway. Scintigraphic imaging studies performed in Swiss mice bearing fibrosarcoma tumors also exhibited selective accumulation of activity in the tumor.

Genetic characterization of 2006-2008 isolates of Chikungunya virus from Kerala, South India, by whole genome sequence analysis

Chikungunya virus (CHIKV), a positive-stranded alphavirus, causes epidemic febrile infections characterized by severe and prolonged arthralgia. In the present study, six CHIKV isolates (2006 RGCB03, RGCB05; 2007 RGCB80, RGCB120; 2008 RGCB355, RGCB356) from three consecutive Chikungunya outbreaks in Kerala, South India, were analyzed for genetic variations by sequencing the 11798 bp whole genome of the virus. A total of 37 novel mutations were identified and they were predominant in the 2007 and 2008 isolates among the six isolates studied. The previously identified E1 A226V critical mutation, which enhances mosquito adaptability, was present in the 2007 and 2008 samples. An important observation was the presence of two coding region substitutions, leading to nsP2 L539S and E2 K252Q change. These were identified in three isolates (2007 RGCB80 and RGCB120; 2008 RGCB355) by full-genome analysis, and also in 13 of the 31 additional samples (42%), obtained from various parts of the state, by sequencing the corresponding genomic regions. These mutations showed 100% co-occurrence in all these samples. In phylogenetic analysis, formation of a new genetic clade by these isolates within the East, Central and South African (ECSA) genotypes was observed. Homology modeling followed by mapping revealed that at least 20 of the identified mutations fall into functionally significant domains of the viral proteins and are predicted to affect protein structure. Eighteen of the identified mutations in structural proteins, including the E2 K252Q change, are predicted to disrupt T-cell epitope immunogenicity. Our study reveals that CHIK virus with novel genetic changes were present in the severe Chikungunya outbreaks in 2007 and 2008 in South India.

Molecular variants of HPV-16 associated with cervical cancer in Indian population

Human papilloma virus is a causative factor in the etiology of cervical cancer with HPV16 being the most prevalent genotype associated with it. Intratype variations in oncogenic E6/E7 and capsid L1 proteins of HPV 16 besides being of phylogenetic importance, are associated with risk of viral persistence and progression. The objective of this multicentric study was to identify HPV-16 E6, E7 and L1 variants prevalent in India and their possible biological effects. Squamous cell cervical cancer biopsies were collected from 6 centres in India and examined for the presence of HPV 16. Variants of HPV-16 were characterized by full length sequence analysis of L1, E6 and E7 genes in 412 samples. Similar distribution of the variants was seen from the different centres/regions, with the European variant E350G being the most prevalent (58%), followed by American Asian variant (11.4%). Fifty six changes were seen in E6 region, 31 being nonsynonymous. The most frequent being L83V (72.3%), Q14H (13.1%) and H78Y (12.1%). Twenty-nine alterations were seen in E7 region, with 12 being nonsynonymous. The most frequent being F57V (9%). L1 region showed 204 changes, of which 67 were nonsynonymous. The most frequent being 448insS (100%), and 465delD (100%), H228D (94%), T292A (85%). The identified variants some new and some already reported can disrupt pentamer formation, transcriptional regulation of the virus, L1 protein interface interaction, B and T cell epitopes, p53 degradation, and thus their distribution is important for development of HPV diagnostics, vaccine, and for therapeutic purpose.

Expression of matrix metalloproteinases (MMP-1, MMP-2 and MMP-9) and their inhibitors (TIMP-1 and TIMP-2) in oral submucous fibrosis

Immunohistochemical staining of formalin fixed, paraffin embedded tissue sections of OSF for MMPs-1,2,9 and their tissue inhibitors TIMP-1and 2 was performed using monospecific antibodies coupled with gelatin zymography (MMP-2 and 9) for measuring enzymatic activity quantitatively and for distinguishing the active from the inactive variants of enzymes. The present study, contrary to earlier reports, recorded statistically significant increase in the levels of stromal expression of MMP-1, MMP-2 and MMP-9 and TIMP-1 and TIMP-2 using monospecific antibodies reacting against tissue antigens. The simultaneous increase in reactivity of MMPs and TIMPs poise difficulty in interpretingthe results of this study. The possible reasons for this result, against the backdrop of existing knowledge, were attempted in this study.

Human papillomavirus and disease mechanisms: relevance to oral and cervical cancers*

Oral squamous cell carcinoma (OSCC) is the sixth most common malignancy and is a major cause of cancer morbidity and mortality worldwide. Carcinoma of the uterine cervix is the most common female malignancy in the world. While cervical cancer is a worldwide disease, oral cancer has the highest incidence in developing countries, especially among tobacco and alcohol users and betel quid chewers. A strong association of cervical and oral cancer with high-risk human papillomavirus (HPV) 16 and 18 infections underlines the importance of the virus in the pathogenesis of these squamous cell carcinomas. Functionally high-risk HPV infection contributes to carcinogenesis and tumor progression predominantly through the actions of two viral oncogenes, E6 and E7. The E6 and E7 genes have been studied in different patient populations and a number of variants have been described. More than 40 variants have been classified and may be related to differences in progression of squamous intraepithelial lesions. The transcription factor, NFkappaB and its activation pathways are frequently targeted by viruses and aberrant constitutive activation of NFkappaB is frequently found in human tumors of diverse tissue origin. Diet-gene interactions are also likely to contribute considerably to the observed inter-individual variations in HPV associated cancer risk, in response to exposures to the nutritional factors that have the potential to promote or protect against cancer.

Expression of folate receptors and heterogeneous nuclear ribonucleoprotein E1 in women with human papillomavirus mediated transformation of cervical tissue to cancer

AIMS

Folate receptors (FRs) mediate cellular uptake of folates in many cancer cells and in folate deficiency heterogeneous nuclear ribonucleoprotein E1 (hnRNP-E1) mediates translational upregulation of FR in cultured cervical cancer cells. hnRNP-E1 can also interfere with human papillomavirus 16 (HPV-16) viral capsid protein synthesis (and thereby HPV proliferation) in vitro. This study aimed to evaluate prospectively the relevance of FR and hnRNP-E1 expression in the normal cervix, cervical dysplasia, and cancer.

METHODS

Cervical tissues from 12 women with normal histology and 69 consecutive women with varying grades of cervical dysplasia and cancer were prospectively evaluated for immunohistochemical expression of FR, hnRNP-E1, proliferating cell nuclear antigen (PCNA), and HPV. There were 22 women with low grade squamous intraepithelial lesions (LGSIL), 22 with high grade squamous intraepithelial lesions (HGSIL), and 25 with invasive cervical carcinoma.

RESULTS

Among normal subjects, 100% and 92% expressed hnRNP-E1 and FR, respectively. FR expression decreased from 91% in LGSIL to 68% and 64% in women with HGSIL and cancer, respectively. Similarly, hnRNP-E1 expression decreased from 86% in LGSIL to 68% and 40% in HGSIL and cancer, respectively. There was a highly significant positive correlation between the extent of FR and hnRNP-E1 expression, and an inverse correlation between HPV infection and hnRNP-E1 expression during progression of cervical dysplasia to cancer.

CONCLUSION

These results are consistent with a hypothesis that reduced hnRNP-E1 expression may be permissive for HPV proliferation and progression to cervical cancer, and support the need for prospective longitudinal studies of hnRNP-E1 expression in HPV-16 infected women.

A novel [186/188Re]-labelled porphyrin for targeted radiotherapy

The concept of labelling a porphyrin, a tumour-avid agent, with a radionuclide to evaluate its potential as a therapeutic modality is reported. A novel water-soluble porphyrin, namely meso-tetrakis[3,4-bis(carboxymethyleneoxy)phenyl]porphyrin, with suitable dicarboxylic acid groups as aromatic substituents in the periphery, was synthesized and characterized. The labelling of this porphyrin with 186/188Re, a beta(-) emitter, was optimized by varying the reaction conditions. The complexation yield was >98% as estimated by paper chromatography in acetone and in saline. The radiochemical purity was found to remain at >98% when stored at 4 degrees C for 24 h. Biodistribution studies in Swiss mice bearing fibrosarcomas showed an uptake of approximately 3.5% per gram of tumour at 30 min post-injection. This uptake in the tumour was retained until 24 h post-injection with major activity showing renal clearance; no significant activity was present in other organs of interest. The tumour/blood and tumour/muscle ratios were observed to be 38 and 5, respectively, at 24 h post-injection, thereby indicating a possible therapeutic potential for tumours.

Preparation and studies with 90Y-labelled particles for use in radiation synovectomy

90Y-FHMA (Ferric hydroxide macroaggregates) and 90Y-HA (hydroxyapatite) were prepared in >95% yield using 90Y from an in-house 90Sr-90Y generator. Most of the particles ranged from 5 to 20 microm in diameter and retained radiochemical purity > 95% in human serum for at least 7 days at 37 degrees C. Gamma camera imaging of normal rabbits after intraarticulation of the particles showed complete retention of activity within the knee cavity with no measurable radioactivity leaching out of the joints over a 96 hour period.

Evolution of Tc-99m in diagnostic radiopharmaceuticals

The progress in diagnostic nuclear medicine over the years since the discovery of 99mTc is indeed phenomenal. Over 80% of the radiopharmaceuticals currently being used make use of this short-lived, metastable radionuclide, which has reigned as the workhorse of diagnostic nuclear medicine. The preeminence of 99mTc is attributable to its optimal nuclear properties of a short half-life and a gamma photon emission of 140 keV, which is suitable for high-efficiency detection and which results in low radiation exposure to the patient. 99mTcO4-, which is readily available as a column eluate from a 99Mo/99mTc generator, is reduced in the presence of chelating agents. The versatile chemistry of technetium emerging from the 8 possible oxidation states, along with a proper understanding of the structure-biologic activity relationship, has been exploited to yield a plethora of products meant for morphologic and functional imaging of different organs. This article reviews the evolution of 99mTc dating back to its discovery, the development of 99Mo/99mTc generators, and the efforts to exploit the diverse chemistry of the element to explore a spectrum of compounds for diagnostic imaging, planar, and single photon emission computed tomography. A brief outline of the 99mTc radiopharmaceuticals currently being used has been categorically presented according to the organs being imaged. Newer methods of labeling involving bifunctional chelating agents (which encompass the "3 + 1" ligand system, Tc(CO)3(+1)-containing chelates, hydrazinonicotinamide, water-soluble phosphines, and other Tc-carrying moieties) have added a new dimension for the preparation of novel technetium compounds. These developments in technetium chemistry have opened new avenues in the field of diagnostic imaging. These include fundamental aspects in the design and development of target-specific agents, including antibodies, peptides, steroids, and other small molecules that have specific receptor affinity.

Genetic polymorphism of CYP1A1, GSTM1 and GSTT1 genes in Indian oral cancer

Oral cancer ranks first among all cancers in males and is the third most common among females in India. Tobacco-derived carcinogens are involved in the development of oral cancer. Environment-gene interaction in oral carcinogenesis is well demonstrated by phase I and II enzymes that are involved in the metabolism of carcinogens. This study looked at the significance of genetic polymorphisms in CYP1A1, GSTM1 and GSTT1 genes in patients with oral cancer. The study included 98 oral cancer patients and 60 age and sex matched healthy controls. Genotypes of CYP1A1, GSTM1 and GSTT1 were determined by PCR-RFLP. GSTM1 null deletion was observed in 49% of oral cancer cases and 33% of control subjects. For GSTT1, 18% of carcinomas and 8% of controls had the null genotype. In the case of CYP1A1 m2 allele, 51% of oral cancers and 17% of normal controls, respectively, had one or both alleles with the isoleucine-->valine substitution. Digestion of the PCR products with enzyme Nco1 revealed polymorphism for CYP1A1 m2 with bands at 263 bp. There was no association between genotypes with tumor size, stage, grade, and age. Since null genotype individuals may possibly be poor detoxifiers with reduced ability to neutralise the reactive carcinogenic intermediates, they may be a high risk category. The frequency distribution of CYP1A1 m2 (Ile/val) genotypes among oral cancer patients was significantly different that from normal controls. The risk of CYP1A1 can be supported by the functional difference between presence of valine and isoleucine; valine type has higher catalytic and mutagenic activity towards benzo[a] pyrene than the isoleucine type. In conclusion, our results suggest that polymorphism in CYP1A1 m2 gene and/or GSTM1 and GSTT1 null genotype may confer an increased risk for oral cancer.

186Re-1,4,8,11-tetraaza cyclotetradecyl-1,4,8,11-tetramethylene phosphonic acid: a novel agent for possible use in metastatic bone-pain palliation

In connection with our work on the development of 186Re-tetra-phosphonates with optimum properties for use in bone pain palliation, a novel cyclic tetraphosphonate derivative, has been synthesized, complexed with 186Re and evaluated with promising results. The ligand, which consists of a cyclic array of tetra-aminomethylphosphonate groups, was synthesized using orthophosphorus acid, 1,4,8,11-tetraazacyclotetradecane and formaldehyde. The labeling conditions with 186Re have been standardized under varying reaction conditions to give maximum yield. In a reaction volume of 1 mL, maximum complexation yield of 98% was observed at pH 2 using 0.1 mg Re (37-370 MBq) for a ligand concentration at 9 x 10(-2) M/L, under heating at 100 degrees C for 30 min with 2 mg of stannous chloride. The complex was found to be stable for 6 days with RC purity remaining approximately 97%. The complex was characterized by paper chromatography in saline and acetone, wherein the R(f) exhibited were 0.9 and 0, respectively. Biodistribution studies of the complex were performed in male Wistar rats. Activity in femur which was observed to be 1.8%/g (equivalent to about 23% of the injected activity in skeleton) at 3 h post injection remained almost constant up to 48 h. Minimum activity was observed in blood and other soft tissues. The complex showed major renal clearance. Scintigraphic images in rabbits after injecting 70-100 MBq of 186Re-CTMP and using a dual head gamma camera were observed to be superior to 186Re-HEDP, prepared by a procedure standardized by us. Insignificant activity was observed in other vital organs. The results suggest the suitability of the complex for further evaluation in higher animals for bone pain palliation.

Radiolabelled monoclonal antibodies against human cardiac myosin

Myocardial infarction (MI) can be monitored using several protein markers including human cardiac myosin (HCM). Monoclonal antibodies were raised against HCM by hybridoma technique. Antimyosin antibody producing clones were identified by ELISA and monoclonality was established by limiting dilution. The antibodies were purified, isotyped and their cross reactions with myosin from other species were estimated. All the clones showed negligible cross reaction with rabbit myosin, but reacted with bovine skeletal myosin to different extents (40-100%). The most avid antibody Mab 4G4 which also strongly reacted with rat cardiac myosin, was labelled with 125I using different oxidising agents such as iodogen, chloramine-T and lactoperoxidase. More than 95% pure radiolabelled antibody could be obtained by gel filtration. The immunoreactivity was retained. Mab 4G4 was also labelled with 99mTc using stannous tartrate as the reducing agent. Radiolabelling yield was approximately 60%, the purity was >95%. Both the radiolabelled preparations were tested for biodistribution in rats--both normal and those with induced MI. Approximately 0.7 % of the injected activity/g was found in the infarcted region and the accumulation of activity in the infarcted heart was 1.5 times that in the normal heart. A very high percentage of activity (80%) accumulated in the thyroid. With further optimisation of labelling and use of F(ab')2 fragments, better delineation of the infarct sites may become possible.

Potential (166)Ho radiopharmaceuticals for intravascular radiation therapy (IVRT)-I: [(166)Ho] holmium labeled ethylene dicysteine

The use of beta(-) emitting radionuclides in the control of restenosis in post angioplasty patients is currently under intense investigation at many leading cardiovascular research centers. (32)P coated metallic stents, (192)Ir wire source and balloons filled with an appropriate radionuclide solution such as of (188)Re, attached to catheter are being studied. (166)Ho has comparable radionuclidic properties to that of (188)Re, can be more easily produced and hence is an attractive alternative to (188)Re. Ethylene dicysteine complex of (166)Ho was prepared and its pharmacological behavior studied. Optimum conditions for the preparation of complex with respect to the reaction time, ligand concentration, pH of the reaction mixture as well as reaction temperature were standardized. The stability of the labeled complex at room temperature as well as at 4 degrees C was determined. Biodistribution pattern of the injected complex in Wistar rats was estimated at 10 min, 30 min and 3 h post injection. This study indicated that >90% of the injected (166)Ho-EC complex was excreted in urine within 3 h post injection, with insignificant retention in any major organ. These studies reveal that (166)Ho-EC could be a viable substitute for (188)Re compounds in radioactive liquid-filled balloon IVRT.

Telomerase, p53 and human papillomavirus infection in the uterine cervix

Human papillomavirus infection is postulated to be a major risk factor for cervical cancer, while more recent data have stressed the clinical significance of telomerase expression during tumorigenesis. This study therefore looked for any relationship between telomerase expression, presence of human papillomavirus (HPV) and expression of the high-risk HPV E6 protein at various phases of tumor progression in the uterine cervix. In addition, accumulation of the p53 protein and total tissue proliferative fraction were also studied. Telomerase was detected using a modified TRAP (telomerase repeat amplification protocol) assay. Expression of p53, Ki 67 and E6 protein was evaluated by immunocytochemistry. Presence of mutant p53 was detected using a mutant-specific ELISA. Type of HPV infection was determined by polymerase chain reaction and Southern blot using type-specific primers and probes. There was a significant correlation between the expression of telomerase with histological grade (r = 0.646, p = 0.00003). Fisher's exact test analysis revealed that the odds ratio of a tissue sample expressing telomerase being a case (high-grade squamous intraepithelial lesion or invasive cancer) was 28.93 (p = 0.0001, 95% CI: 7.22, to 115.94). High-risk HPV-infected tissues and those expressing E6 showed increased telomerase expression (r = 0.555, p = 0.00001). Similarly, accumulation of p53 protein and increased cell proliferation (Ki 67 index) also correlated to the presence of telomerase (r = 0.661, p = 0.000004 for p53 and r = 0.647, p = 0.000003 for Ki 67). There was no correlation between telomerase expression and presence of p53 mutation. Activation of telomerase thus appears to be associated with high-risk-HPV infection, accumulation of inactive p53 protein and increased cell proliferation in cervical lesions.

Tc-99m and Re-186 complexes of tetraphosphonate ligands and their biodistribution pattern in animal models

The syntheses of four alpha-aminomethyl phosphonates and their complexation studies with (99m)Tc and (186/188)Re are reported. Complexation conditions were standardized to give maximum yields, which ranged from 90-97%. The yields of complexation were estimated by paper chromatography. The (99m)Tc complexes were stable for more than 4 h, while the (186/188)Re complexes were stable for 3-8 days when stored at 4 degrees C. Biodistribution of these complexes in Wistar rats were carried out, and the uptake in bone and other soft tissue are detailed. Bone uptake of the (99m)Tc complexes varied from 40-60% at 30 min postinjection depending on the ligands. The uptake in soft tissue was minimum with all the complexes. A comparison of the biodistribution studies of the (99m)Tc complexes with that of the well-established radiopharmaceutical (99m)Tc-MDP was carried out for the purpose of evaluating the efficacy of the radiopharmaceutical preparation with the complexes of these ligands. The bone uptake of the (186/188)Re complexes varied from 19-28% corresponding to 1.6-3% per g at 3 h postinjection. The residual activity in both (99m)Tc and (186/188)Re complexes showed renal clearance.

Apoptosis, angiogenesis and proliferation: trifunctional measure of tumour response to radiotherapy for oral cancer

Local recurrence is a significant problem following radiotherapy in oral carcinoma and hence there is a paramount need for predictive markers. This study therefore analysed the predictive value of pre-treatment status of angiogenesis, apoptosis, expression of apoptosis regulatory p53, bax and bcl-2 proteins as well as tissue proliferation in relation to tumour response to radiotherapy. Sixty-nine histologically defined invasive carcinoma lesions were included in the study. Extent of apoptosis was defined morphologically and by the TUNEL (Tdt-mediated dUTP biotin nick end labelling) assay. Expression of apoptosis regulatory p53, bax and bcl-2 proteins were evaluated by immunocytochemistry. Mutant p53 protein was detected using a mutant p53-specific ELISA. The extent of tissue proliferation was evaluated by cyclin D1 expression. Angiogenesis was evaluated by CD34 antigen expression. All patients were treated with radical radiotherapy and followed up for 36 months. High levels of p53 protein detected by immunocytochemistry were found to be associated with poor response to treatment or disease relapse. Detection of mutant p53 protein also showed significant association with poor prognosis. Low levels of angiogenesis had a correlation with recurrence status. Tumours showing less vascularisation as well as increased apoptosis had a poor prognosis. Expression of p53 and bcl-2 proteins showed direct correlation with angiogenesis. There was no correlation between clinical status and any of the experimental parameters with histopathological grades of invasive lesions. Presence of mutant p53 protein is suggestive of poor tumour response to radiotherapy. Expression of p53 and increased apoptosis in less vascularised tumours is associated with treatment resistance. A predictive assay based on these results designed to analyse individual tumour samples showed presence of apoptotic cells near the vasculature to be indicative of good prognosis, while absence of apoptotic cells or highly proliferative cells and/or expression of bcl-2 protein in cells around the vasculature to be an indicator of poor prognosis.

Development of a condemned mucosa syndrome and pathogenesis of human papillomavirus-associated upper aerodigestive tract and uterine cervical tumors

High-risk human papillomaviruses (HPVs) have been shown to be involved in the pathogenesis of many squamous carcinomas, particularly those of the uterine cervix. A number of random studies have also reported association of high-risk HPV subtypes with cancers of the oral cavity, larynx, hypopharynx, and esophagus. The roles of other molecular factors involved during HPV infection in these tumors still remain unclear. Recent findings from our laboratories have suggested possible mechanisms associated with HPV-mediated carcinogenesis. Both p53 mutation-dependent and mutation-independent pathways may be associated with HPV-mediated carcinogenesis, the former mainly in upper aerodigestive tract tumors (UADT) and the latter in cervical tumors. In cervical tumors, inactivation of the p53 tumor suppressor protein by the E6 gene product of high-risk HPVs and mutation of the p53 gene in UADT is associated with alterations in the apoptotic regulatory bcl-2 and bax genes, leading to downregulation of programmed cell death (PCD) and increased cell proliferation. HPV infection is also associated with increased tissue angiogenesis and activation of telomerase. Altered kinetics of telomere fragments is evident in HPV-infected tissue. We therefore believe that the combined manifestations of all these factors may contribute to development of a "condemned mucosa syndrome" facilitating development UADT and cervical cancers. A distinct step in the pathogenesis of both types of tumors may only be in the mode of p53 inactivation, whereas all other events appear to be strongly correlated to the presence of HPV. The development and validation of such a molecular model has significant clinical priority. It can be used to identify target populations or individuals for intervention, to monitor effects of intervention, and to determine which individuals or groups are at increased risk of developing cancer.

188Re-ethylene dicysteine: a novel agent for possible use in endovascular radiation therapy

Several agents, such as 188ReO4-, 188Re-MAG3 and 188Re-DTPA are currently under investigation as radiation sources in liquid-filled balloons for prevention of restenosis following coronary angioplasty. Bearing in mind the risk factor associated with leakage of radioactivity in the event of balloon rupture, the criteria sought in selecting suitable agents for endovascular radiation therapy (EVRT) are rapid clearance and low dose to vital organs. Since 99Tcm labelled ethylene dicysteine (EC) is a well established agent for renal tubular function imaging, the use of 186Re-ethylene dicysteine as a potential agent for prevention of restenosis after angioplasty has been evaluated previously. Therefore, it was of interest to evaluate the applicability of the more potential isotope of rhenium, 188Re, a high energy beta-emitter (Ebetamax = 2.12 MeV) with a suitable T 1/2 = 16.9 h, obtainable carrier-free from the 188W-188Re generator, as an attractive and alternative radionuclide for labelling with L,L-EC. In this paper, the preparation and pharmacological behaviour of the 188Re complex of ethylene dicysteine are reported. The complex can be prepared in high yields (99.5%) under optimized conditions of pH 2-3, at a ligand concentration of 15 mM, 50 microg (0.18 mM) carrier rhenium and using 2 mg x mL(-1) stannous chloride. On storage at 4 degrees C, the RC purity was more than 97% after 48 h when prepared under optimum conditions. Biodistribution studies in Wistar rats showed the desired characteristics of fast blood clearance and low retention of activity in the vital organs (< 2% in intestine, < 1% in stomach, < 0.5% in liver) with a high renal excretion (90.65+/-0.6%) at 3 h post-injection. These results confirm the advantages of using the 188Re-EC complex compared with perrhenate and other rhenium radiopharmaceuticals currently being used in balloons for EVRT.

High-risk human papillomavirus infection and E6 protein expression in lesions of the uterine cervix

Pathologic and epidemiologic investigations carried out over the past several years have provided evidence that carcinogenesis in the uterine cervix is a multi-step process involving discreet preinvasive stages. Molecular epidemiologic data also indicate that human papillomavirus (HPV) infection is a critical factor in the tumor progression process. In vitro studies have shown that for the initiation and maintenance of the malignant phenotype, the expression of the HPV-transforming protein E6 is required. The E6 protein produced by the high-risk HPV types 16 and 18 can bind to and inactivate the tumor suppressor protein p53 leading to deregulated proliferation and defective apoptosis, thus facilitating tumor progression. Therefore, determination of the HPV genotype alone may not be sufficient in assessing tumor progression in the uterine cervix. In the present study, a total of 623 cervical tissue samples at various phases of tumor progression were assessed for HPV infection by nonisotopic in situ hybridization (NISH) and for HPV 16/18 E6 protein expression by immunocytochemistry. There was significant correlation between the extent of histological abnormality and HPV infection. Significant correlation (r = 0.707, p = 0.000) was observed between the presence of HPV 16 and high-grade squamous intraepithelial lesions (SILs) and invasive cancer. The odds ratio of a cervical tissue infected with HPV 16 falling into these two categories was 44.57 (95% CI: 27.10, 73.30). The E6 protein also was mostly detected in high-grade SILs and cervical cancer tissue expressing either HPV 16 or 18. It was less frequent in low-grade SILs infected with HPV 16/18 and was absent in benign cervical tissue infected with HPV 16. The odds ratio of an HPV-16/18-infected cervical tissue positive for E6 being a high-grade SIL or invasive cancer was 16.20 (95% CI: 6.06, 43.33). These results thus show the clinical utility of HPV characterization along with the analysis of the transforming protein E6 in the assessment of tumor progression in the uterine cervix.

Apoptosis: future directions in cancer therapy

Cancer as a multifactorial disease results in gain of immortality due to defective apoptosis. The primary mode of cell death by apoptosis induced by various modes of treatment often fail in vivo. The in vitro environment is less complex while the in vivo environment is influenced by various external regulatory signals besides the existence of multiple, parallel and independent apoptotic pathways. Further, specific preference for an apoptotic pathway in a certain cell type would significantly alter the apoptotic responses. Identification of defects in preferred pathways and choosing alternative and potentially inducible pathways would help in deciding on apoptosis-based treatment protocols. Mechanisms involved in the execution of apoptosis may also not be unique to apoptotic pathways since similar events, possibly with strict control, do occur during mitosis. Further evaluation may yield new dimensions to apoptosis and apoptosis-based therapy.

In situ apoptosis in the thyroid

Recent evidence has emphasized the importance of programmed cell death, or apoptosis, in the maintenance of tissue homeostasis and pathogenesis of tumors. This study analyzed the significance of apoptosis in relation to the expression of p53 and bcl-2 proteins, tissue proliferation defined by Ki-67 expression, and tissue histology in thyroid tissue. Extent of apoptosis was defined by morphological criteria and the terminal deoxynucleotidyl transferase-mediated deoxy uridine triphosphate (dUTP) biotin nick end labeling (TUNEL) assay. Immunocytochemistry was performed for p53, bcl-2, and Ki-67 expression. There was good correlation between TUNEL-reactive cells and morphological evaluation criteria for apoptosis. The extent of apoptosis was significantly associated with the type of thyroid lesion (r = 0.66990, p = 0.000012), both proliferative (namely multinodular goiter) and neoplastic (benign and malignant). A higher extent of apoptosis was evident in medullary and anaplastic carcinomas. Apoptosis also correlated to p53 protein accumulation (r = 0.485, p = 0.00041) and Ki-67 immunoreactivity (r = 0.435, p = 0.001). An inverse correlation was observed between bcl-2 expression and the extent of apoptosis (r = -0.33369, p = 0.01912). A direct correlation was also observed between p53 expression and Ki-67 immunoreactivity (r = 0.623, p = 0.0002). By inhibiting apoptosis, bcl-2, may cause a shift in tissue kinetics toward the preservation of genetically aberrant cells, thereby facilitating tumor progression. These results imply that rapidly proliferating tumors appear to have a high cell turnover state in which there may be increased chance of apoptosis among the proliferating cells. The ability of apoptosis to occur in the presence of a possibly mutant p53 protein suggest the existence of at least two p53 dependent apoptotic pathways, one requiring activation of specific target genes and the other independent of it. However, keeping in mind the limited number of subjects studied in each subgroup and the rather low correlation coefficients, these possibilities would have to be substantiated in a larger study population.

[(186/188)Re] rhenium-ethylene dicysteine (Re-Ec): preparation and evaluation for possible use in endovascular brachytherapy

188ReO(4)(-), (188)Re-MAG(3), and (188)Re-DTPA are currently under investigation as radiation sources in liquid-filled balloons for prevention of restenosis following coronary angioplasty. Because (99m)Tc-labeled ethylene dicysteine (EC) is a well-established agent for renal tubular function imaging, the use of [(188)Re] rhenium-labeled EC as a potential agent for prevention of restenosis after angioplasty is worth evaluation. In this article, the preparation and pharmacological behavior of [(188/186)Re]Re complex of EC are reported. The yield of the Re complex was optimized by varying the parameters of complexation. The complex prepared under the optimized conditions was found to be stable over a period of 7 days when stored at pH 2 and at 4 degrees C. The pharmacological behavior of [(188/186)Re]Re-EC confirms its similarity to (188)Re-MAG(3) and its superiority over (188)ReO(4)(-) for use in endovascular brachytherapy.

Syntheses and radiolabeling of cysteine-oximes and pharmacological behaviour of their 99mTc complexes

Synthesis of two novel ligands using 2-oximino-butan-3-one and L-ethyl cysteinate is described. The synthetic procedure involved the formation of Schiffs base by the condensation of the amino group of L-ethyl cysteinate with the carbonyl group of 2-oximino-butan-3-one to provide the ligand I, N'(butan-2-enyl-3-oximino)ethyl cysteinate, followed by reduction of the Schiffs base with sodium borohydride to ligand II, N'(3-oximinobutyl)ethyl cysteinate. The ligands were characterised by NMR spectroscopy. Complexation studies with 99mTc were carried out using stannous tartrate as the reducing agent. The complexes were characterised by paper chromatography, thin layer chromatography and paper electrophoresis techniques. The complexes are formed in high yields when the reactions were carried out at pH 7-9. The 99mTc complex with ligand I is formed instantaneously while the 99mTc complex with ligand II is formed at a slower rate. The complexes were found to be neutral but the lipophilicity of the complex with ligand I was higher than that of the complex of ligand II. The stability of the complex with ligand I was relatively poor as compared to that of the complex with ligand II. Biodistribution studies of the 99mTc complexes of ligand I and II showed rapid blood clearance with hepatobiliary uptake. Renal excretion of the complex of ligand II was more than that observed for the complex of ligand I. The complexes did not show significant uptake in brain in spite of their favourable properties such as neutrality, lipophilicity and structural similarity with both ECD and HMPAO.

Mutant p53 protein, Bcl-2/Bax ratios and apoptosis in paediatric acute lymphoblastic leukaemia

PURPOSE

The Bcl-2 family of proteins regulates a late step in the apoptosis pathway. Bcl-2 protein is believed to be involved in imparting resistance to programmed cell death or apoptosis induced by chemotherapeutic agents and radiation. The anti-apoptotic function of the Bcl-2 protein appears to be modulated by its ability to heterodimerize with other members of the gene family, predominantly Bax, a protein favouring induction of apoptosis. Susceptibility to undergoing apoptosis may, therefore, be dependent on the ratio between Bcl-2 and Bax. Both Bax and Bcl-2 are regulated by the tumour-suppressor protein p53. The present study therefore aims to study the significance of the Bcl-2:Bax ratio, p53 expression and apoptosis in paediatric acute lymphoblastic leukaemia (ALL).

METHODS

Expression of Bax, Bcl-2 and p53 was determined by immunocytochemistry, and apoptosis was evaluated by an enzymatic end-labelling technique using biotin-dUTP and further confirmed by annexin binding. The presence of mutant p53 was determined using a mutant-p53-specific enzyme-linked immunosorbent assay (ELISA).

RESULTS

A total of 32 cases and 20 controls were evaluated. Bcl-2 was found to be expressed in 22/32 of the ALL cases. Pretreatment (spontaneous) apoptosis was observed in 23/32 cases. The mean pretreatment apoptotic index was 11.34 +/- 2.04% with a median value of 7.5%.

CONCLUSIONS

There was a positive correlation between apoptosis and Bax expression (r = 0.5044; P = 0.0038). There was good correlation between the immunoreactivity of p53 and detection of mutant p53 by ELISA (r = 0.4605; P = 0.0079). The apoptosis index showed a negative borderline correlation to the expression of Bcl-2 protein (r = -0.3181; P = 0.076). There was an inverse correlation between extent of apoptosis and the presence of mutant p53 protein (r = -0.4732; P = 0.006). p53 protein expression also showed a correlation with both Bcl-2 (r = 0.4647; P = 0.007) and Bax (r = 0.4128; P = 0.018). The Bcl-2/Bax ratio, however, showed no significant correlation with apoptosis (r = -0.3131; P = 0.08) or with p53 expression. No significant association was evident between clinical and laboratory parameters with the Bcl-2/Bax protein expression except lymphadenopathy (r = 0.5774; P = 0.03). However, Bax expression showed a borderline correlation with the immediate tumour response to chemotherapy (r = -0.338; P = 0.0628). These patients are being followed-up to look for any association between clinical outcome, Bcl-2/Bax ratio and apoptosis.

Immunophenotype of mutant ras p21 and early response to radiotherapy in cancer of the uterine cervix

Previous studies have postulated that ras gene mutations may influence cellular response to radiotherapy. However, clinical studies have often been limited by the cumbersome methodology associated with DNA analysis. The availability of ELISA method has eventually made clinical evaluation of ras gene mutation feasible. In this study ras mutation by in vitro identification of four mutant forms of p21 ras in cervical tumor tissue extracts was analyzed. Mutant ras proteins were evaluated by an Enzyme Linked Immunosorbent Assay (ELISA). Expression of ras p21 mutations was studied in 101 patients, and a correlation between pre-treatment experimental analyses and the clinical status of the patient after radiotherapy (up to 16 months follow up) was established. There was no correlation between the presence of Val 12 p21 and tumor response to radiotherapy. Yet, presence of the other three mutant proteins had significant relationship to treatment outcome. Detection of Arg 12 mutation was more common in patients who either had residual disease or developed recurrences (28%) as compared to those remaining disease-free (1.5%). The presence of the Arg 12 mutation therefore correlated to poor prognosis (r = 0.445, p = 0.0000). Similarly, the Asp 12 mutation was also more common in patients with residual/recurrent disease (25%) as compared to patients remaining disease-free (3%). Asp 12 mutation also showed a correlation to treatment outcome (r = 0.337, p = 0.00057). Asp 13 mutation was more frequent in patients with residual or recurrent disease (28%) as compared to those remaining disease-free (4.6%). On the basis of laboratory evidence ras genes appear to be involved as modulators of tumor response to radiation therapy. This understanding of the involvement of specific genes in radioresistance will result in the improvement of potential therapies that can be targeted at specific genes, through approaches such as selective inhibition by anti-sense oligonucleotides.

Decreased programmed cell death in the uterine cervix associated with high risk human papillomavirus infection

The relationship between apoptosis, apoptosis regulatory proteins, cell proliferation and human papillomavirus infection during various phases of tumor progression in the uterine cervix was studied. Apoptosis was defined by morphological criteria and the TUNEL assay. Expression of p53, bcl-2, bax, cyclin D1, Ki 67 and E6 protein was evaluated by immunocytochemistry. Presence of mutant p53 was detected using a mutant specific ELISA. Type of HPV infection was determined by PCR using type specific primers. Apoptosis showed significant negative correlation with increasing histological abnormality (p=0.0005). Higher tumor cell proliferation was associated with increasing histological abnormality (p=0.001 for Ki 67 and cyclin D1). There was significant correlation between histological grade and immunoreactivity of p53 (p=0.0001 ) and bcl-2 (p=0.0002). However, mutant p53 was expressed by only 12 of the 230 samples. Expression of bax and the bax/bcl-2 ratio showed an inverse correlation to histological grade (p=0.0003 and 0.0001, respectively). There was also an inverse correlation between extent of apoptosis and immunoreactivity of p53 (p=0.0001) and bcl-2 (p=0. 0001). A significant positive correlation between expression of the bax protein and apoptosis was evident (p=0.0001). HPV infection significantly correlated to the extent of histological abnormality (p=0.0001). High risk HPV-E6 protein also showed this significant correlation (p=0.0002). There was an inverse correlation between apoptosis and HPV infection (p=0.0002). High risk HPV infection was associated with decreased apoptosis and also increased human cell proliferation. Lowest levels of bax/bcl-2 ratio was also associated with HPV 16 and 18 infection (p=0.0001). Modulation of apoptosis and apoptotic regulatory proteins by high risk HPV infection may be an important factor in the development of cervical cancer.

Preparation of [186Re]Re-DMSA and its bio-distribution studies

99mTc(V)-DMSA is widely used for imaging medullary carcinoma and hence 186/188Re(V)-DMSA is suggested as a potential agent for treating medullary carcinoma. In the present paper, we report the work carried out for the preparation of [186Re]Re(V)-DMSA and it's bio-distribution studies in Wistar rats. The complex was prepared by reducing 186Re (100 micrograms, 0.54 microM, approximately 150 MBq) in the presence of DMSA (2 mg, 11 microM) with stannous chloride (0.4 mg, 2.2 microM) in acidic medium at pH 2. The reaction was taken to completion by heating the complex in a boiling water bath for 30 min. Bio-distribution studies carried out revealed that pharmacological behaviour of 186Re(V)-DMSA is similar to that of 99mTc(V)-DMSA except that the kidney uptake is marginally higher. The kidney uptake reduced significantly when the pH of the complex was adjusted to 8 prior to injection. The in vitro stability studies of this complex suggest that the product formed is stable and could be used for clinical trials.

Preparation, stability studies and pharmacological behavior of [186Re]Re-HEDP

99mTc-HEDP is widely used as a bone imaging agent and its Re analog [186Re]Re-HEDP is now well established as a therapeutic radiopharmaceutical for palliation of pain due to bone metastases. In the present paper, we report the work carried out for the preparation of stable 186Re-HEDP which retains RC purity up to 5 days when stored at 4 degrees C. 186Re was prepared by irradiation of natural Re metal at a flux of 3 x 10(13) neutrons/cm2/s for seven days and processed after a cooling period of four days. The specific activity of 186Re formed was approximately 35 mCi/mg. A complex with RC purity > 98% could be prepared by varying the reaction conditions. By carefully optimizing the reaction and storage conditions, a complex which was stable for over 4 days could be synthesized. Bio-distribution studies carried out in rats revealed approximately 30% bone uptake of 186Re-HEDP at 3 h postinjection which remained almost constant for 48 h, at which time there was negligible activity in other organs.

Radiochemical studies of 99mTc complexes of modified cysteine ligands and bifunctional chelating agents

The synthesis of four novel ligands using the amino-acid cysteine and its ethyl carboxylate derivative is described. The synthetic method involves a two-step procedure, wherein the intermediate Schiff base formed by the condensation of the amino group of the cysteine substrate and salicylaldehyde is reduced to give the target ligands. The intermediates and the final products were characterized by high resolution nuclear magnetic resonance spectroscopy. Complexation studies of the ligands with 99mTc were optimized using stannous tartrate as the reducing agent under varying reaction conditions. The complexes were characterized using standard quality control techniques such as thin layer chromatography, paper electrophoresis, and paper chromatography. Lipophilicities of the complexes were estimated by solvent extraction into chloroform. Substantial changes in net charge and lipophilicity of the 99mTc complexes were observed on substituting the carboxylic acid functionality in ligands I and II with the ethyl carboxylate groups (ligands II and IV). All the ligands formed 99mTc complexes in high yield. Whereas the complexes with ligands I and II were observed to be hydrophilic in nature and not extractable into CHCl3, ligands III and IV resulted in neutral and lipophilic 99mTc complexes. The 99mTc complex with ligand II was not stable and on storage formed a hydrophilic and nonextractable species. The biodistribution of the complexes of ligands I and II showed that they cleared predominantly through the kidneys, whereas the complexes with ligands III and IV were excreted primarily through the hepatobiliary system. No significant brain uptake was observed with the 99mTc complexes with ligands III and IV despite their favorable properties of neutrality, lipophilicity, and conversion into a hydrophilic species. These ligands offer potential for use as bifunctional chelating agents.

Cellular manifestations of human papillomavirus infection in the oral mucosa

BACKGROUND AND OBJECTIVES

Human papillomavirus infection has been suggested to play a role in the development of epithelial carcinomas, particularly those of the uterine cervix. Less information is available on the role of the virus in oral lesions. It has been proposed that the viral oncoproteins specifically complex with the products of cellular tumor suppressor gene, namely E6 with p53 and E7 with retinoblastoma gene product. Inactivation or mutation in p53 gene is also known to result in loss of control over the cell cycle and increases in tumor proliferation rates. The present study examines the role of HPV infection in relation to p53 and the extent of the tumor proliferative compartment reflected by cyclin D1 and Ki-67 expression during various phases of tumor progression in the oral epithelium.

METHOD

Nonisotopic in situ hybridization (NISH) was performed to detect HPV 6/11 and 16/18. Expression of p53, cyclin D1, Ki-67, and the HPV 16/18 E6 protein were detected by immunocytochemistry.

RESULTS

There was significant correlation between the extent of histological abnormality and HPV infection. A correlation (r = 0.250, P = 0.0089) was evident between the presence of HPV 16 and occurrence of invasive cancer. Expression of the tumor suppressor p53 protein also showed significant positive correlation with histology (r = 0.475, P = 0.00004). The tumor proliferative fraction also increased with the extent of histological abnormality (r = 0.387, P = 0.0003 for cyclin D1 and r = 0.463, P = 0.0001 for Ki 67). Accumulation of p53 and increase in tumor proliferation also correlated to the presence of HPV infection (r = 0.511, P = 0.00003 for p53; r = 0.478, P = 0.00002 for cyclin D1 and r = 0.521, P = 0.00004 for Ki-67).

CONCLUSIONS

The present study thus demonstrates the importance of HPV infection in oral tissue. Expression of the high-risk HPV 16/18 E6 protein also appears to be a critical event along with aberrant p53 expression. These results are of significance to the molecular epidemiology of oral cancer and may also be used to supplement and elaborate the diagnosis of oral lesions.

Increased angiogenesis in the uterine cervix associated with human papillomavirus infection

We studied the relationship between angiogenesis (using the CD34 antibody), the presence of human papilloma virus (HPV) infection, HPV E6 protein expression and the accumulation of p53 protein at various phases of tumour progression in the uterine cervix. Expression of CD34, p53 and HPV E6 protein was evaluated by immunocytochemistry. Presence of the mutant p53 was detected using a mutant specific ELISA, and the type of HPV was determined by the Polymerase Chain Reaction. A total of 230 cervical tissue samples were analyzed and included 40 cases of apparently normal cervical epithelium, 37 low grade squamous intraepithelial lesions (SILs), 43 high grade SILs, 36 well-differentiated squamous cell carcinomas (DSCC), 31 moderately differentiated (MDSCC) and 43 poorly differentiated carcinomas (PDSCC). There was an excellent correlation between the extent of angiogenesis and histological abnormality (r = 0.912, p = 0.000004). The least extent of angiogenesis was seen in normal cervical tissue and low grade SILs where the mean (low power) intra lesional vascular density (ILVD) was 12 +/- 1.13 and 25.66 +/- 5.20, respectively. In high grade squamous intraepithelial lesions (SILs), the mean ILVD value was 80.84 +/- 25.57. In well-differentiated squamous cell carcinomas (WDSCC's) the mean value was 144.22 +/- 28.67 while in moderately differentiated squamous cell carcinomas (MDSCC's) the mean value was 166.29 +/- 34.95 and in poorly differentiated tumours (PDSCC's) 192.42 +/- 27.98. The extent of angiogenesis also correlated to presence of HPV (r = 0.505, p = 0.00001). Increased CD34 expression was associated with the presence of HPV types 16 and 18. A similar correlation was also evident in HPV, 16/18 infected cases expressing the E6 protein (r = 0.612, p = 0.000001). CD34 expression also correlated well with p53 accumulation (r = 0.859, p = 0.000002). Presence of HPV infection significantly correlated with the extent of histological abnormality (r = 0.467, p = 0.00001). Expression of E6 also showed this significant correlation (r = 0.644, p = 0.00002). Accumulation of p53 was significantly more elevated in HPV 16-infected lesions (r = 0.518, p = 0.00001) and E6-expressing cells (r = 0.650, p = 0.000004). Only 12 of the 230 cases analyzed showed presence of the mutant p53 protein. Angiogenesis appears to increase with histological abnormality in the uterine cervix. Angiogenesis also appears to be influenced by high risk HPV infection, the expression of the E6 transforming protein and the p53 tumour suppressor protein.

Use of Traditional Eye Medicines by corneal ulcer patients presenting to a hospital in South India

PURPOSE

To investigate the nature and frequency of use of Traditional Eye Medicine (TEM) for corneal ulcer in patients from predominantly rural background.

METHODS

We documented the the use of TEM by corneal ulcer patients presenting to a tertiary eye-care centre in South India during two months of 1996.

RESULTS

Of 283 patients enrolled in the study, 135 (47.7%) of the patients used TEM. There was no difference with regard to age and sex distribution of patients using TEM and those who did. Patients with history of trauma were more likely to use TEM. Common forms of TEM used were human breast milk 61(45.2%), leafy matter 40(29.6%), castor oil 16 (11.9%), and hen's blood 8 (5.9%).

CONCLUSION

Though the awareness of intraocular lens implantation for cataract surgery is very high in this segment of the population, it is still tragic that an awareness of primary eye care following trauma has not been created. Health education is mandatory to prevent this avoidable cause of blindness.

De novo programmed cell death in oral cancer

AIM

The importance of programmed cell death or apoptosis in the maintenance of tissue homoeostasis and the pathogenesis of oral cancer was analysed in relation to apoptosis regulatory proteins, tissue proliferation and tumour histology.

METHODS AND RESULTS

The extent of apoptosis was defined by morphological criteria and the TUNEL (terminal deoxy nucleotidyl transferase-mediated dUTP biotin nick end labelling) assay. p53, bax, bcl-2 and cyclin D1 expression was evaluated by immunocytochemistry. The presence of mutant p53 was analysed using a mutant p53-specific ELISA. An inverse correlation was observed between TUNEL reactivity and histology of the lesion (r = -0.555, P = 0.0001). There was also correlation between TUNEL reactivity and immunoreactivity of apoptosis regulatory proteins. p53 (r = 0.641, P = 0.00023), bcl-2 (r = -0.642, P = 0.00014) and bax (r = 0.651, P = 0.00002). The presence of mutant p53 protein showed an inverse correlation to the extent of apoptosis (r = - 0.301, P = 0.00063). Significant correlation was evident between the bax/bcl-2 ratio and TUNEL (r = 0.652, P = 0.00001) as well as between cyclin D1 and TUNEL reactivity (r = 0.577, P = 0.00001).

CONCLUSIONS

Results from this study suggest that apoptosis decreases as histological abnormality increases. Apoptotic regulatory proteins are also altered in a histologically dependent manner. Deregulated proliferation occurs simultaneously with decreased apoptosis during tumour progression in the oral mucosa.

bcl-2 immunoreactivity but not p53 accumulation associated with tumour response to radiotherapy in cervical carcinoma

PURPOSE

This study seeks to define the role of pretreatment expression of the tumour-suppressor p53 protein and the anti-apoptotic protein bcl-2 and their relationship to tumour response to radiotherapy in cervical carcinoma.

METHODS

A total of 101 patients were evaluated and the possibility of a correlation done between the pretreatment status of the two proteins and clinical outcome following radiotherapy was investigated. Such patients were either disease-free (group 1, n = 65) or had residual/recurrent disease (group 2, n = 36) at a 16-month follow-up. p53 and bcl-2 protein expression was determined by immunocytochemistry. The presence of mutant p53 was detected by a mutant specific p53 enzyme-linked immunosorbent assay.

RESULTS

There was no correlation between p53 immunoreactivity or the presence of mutant p53 protein and disease status after treatment. Expression of bcl-2 protein, however, showed significant pretreatment correlations with the final disease outcome (r = 0.643, P = 0.0001). Moreover the odds ratio of a tumour expressing moderate to intense levels of bcl-2 responding poorly to radiotherapy was 27.2 (95% CI 6.0, 123.3).

CONCLUSIONS

bcl-2 protein functions in an anti-oxidant pathway to prevent apoptosis. Since radiotherapy efficacy depends on adequate DNA damage caused by free-radical generation, increased expression of bcl-2 may result in tumours becoming less responsive to radiation. Mutation of the p53 gene, however, is a rare event in cervical cancer. Since bcl-2 is negatively regulated by p53, it could be presumed that the p53 detected in the tumour cells may be non-functional or inactive possibly because of interaction with proteins such as E6 or mdm-2.

Synthesis of heptadentate (N4O3) amine-phenol ligands and radiochemical studies with technetium-99m

Heptadentate amine-phenol ligands with N4O3 donor atoms for coordination were synthesized by condensing tris(2-aminoethyl)amine with salicylaldehyde or acetophenone and reducing the Schiff bases formed with NaBH4. The ligands were characterized by 1H and 13C nuclear magnetic resonance spectroscopy. Radiochemical studies were carried out with no-carrier-added 99mTc and 99mTc spiked with 0.1-100 microM of 99Tc. Complexation yields were estimated from thin layer chromatography, paper electrophoresis, and solvent extraction studies. 99mTc complexes were formed in yields better than 90% with the amine-phenol ligands. The complexes were found to be neutral and lipophilic. Biodistribution studies of the 99mTc complexes showed that clearance was mainly through the hepatobiliary system.

Technetium-99m complexes of polydentate amine-pyrrole and amine-thiophene ligands

Novel polydentate amine-pyrrole and amine-thiophene ligands were synthesized and characterized by 1H and 13C NMR spectroscopy. Radiochemical studies with 99mTc were carried out at 0.1-100 microM of technetium. Complexation yields were estimated from thin layer chromatography (TLC), paper electrophoresis, and solvent extraction studies. The 99mTc complexes formed were found to be neutral and lipophilic. Complexes with the corresponding imine-ligands were formed in lower yields. Biodistribution studies of the 99mTc complexes of these ligands showed no significant uptake in brain or heart, and the clearance was mainly through the hepatobiliary system.

Angiogenesis during tumor progression in the oral cavity is related to reduced apoptosis and high tumor cell proliferation

Angiogenesis, the growth of new blood vessels, is believed to aid tumor progression and metastasis. Tumor progression is also influenced by the extent of proliferation and apoptosis. This study, therefore, analyzed in lesions of the oral cavity, the significance of angiogenesis in relation to apoptosis, expression of apoptosis regulatory p53, bax and bcl-2 proteins as well as tissue proliferation defined by cyclin D1 expression. Results from this study suggest that angiogenesis increases as histological abnormality increases in the oral mucosa. The expression of apoptosis regulatory proteins also appears to be altered in a histologically dependent manner. The correlation seen between CD34 expression, cyclin D1 and TUNEL reactive cells suggests that increased angiogenesis, decreased apoptosis and deregulated proliferation occur simultaneously during tumor progression in the oral mucosa. Presence of a mutant p53, increased bcl-2 expression and altered bax expression are also involved in this complex process.

Spontaneous programmed cell death in infiltrating duct carcinoma: association with p53, BCL-2, hormone receptors and tumor proliferation

Recent evidence has emphasized the importance of programmed cell death or apoptosis in the maintenance of tissue homeostasis and pathogenesis of tumors. This study, analyzed in breast cancer, investigates the significance of apoptosis in relation to the expression of p53 and bcl-2 proteins, tissue proliferation defined by Ki-67 expression, hormone receptors and tumor grade. The extent of apoptosis was defined by morphological criteria and the TUNEL (Tdt-mediated dUTP biotin nick end labelling) assay. Immunocytochemistry was performed for p53, bcl-2, estrogen receptor, progesterone receptor and Ki-67 expression. Mutant p53 protein was detected using a mutant specific ELISA. Immunoreactivity of p53 significantly correlated with the presence of mutant p53 protein detected by ELISA (r = 0.654, p = 0.00001). An inverse correlation was observed between bcl-2 expression and the extent of apoptosis (r = -0.33369, p = 0.01912). The extent of apoptosis directly correlated with p53 protein accumulation (r = 0.485, p = 0.00041), Ki-67 immunoreactivity (r = 0.435, p = 0.001), histopathological grade (r = 0.492, p = 0.0003), tumor size (r = 0.326, p = 0.023) and lymph node status (r = 0.287, p = 0.047). A direct correlation was also observed between p53 expression and Ki-67 immunoreactivity (r = 0.623, p = 0.0002). There was no statistically significant association between estrogen and progesterone receptor status and apoptosis. In addition, the TNM stage of the disease correlated with immunoreactivity of p53 (r = 0.572, p = 0.00012) and Ki-67 (r = 0.3744, p = 0.00818). Bcl-2, by inhibiting apoptosis, may cause a shift in tissue kinetics towards the preservation of genetically aberrant cells, thereby facilitating tumor progression. These results imply that rapidly proliferating tumors appear to have a high "cell turnover state" in which there may be an increased chance of apoptosis amongst the proliferating cells. The ability of apoptosis to also occur in the presence of mutant p53 protein suggests the existence of at least two p53-dependent apoptotic pathways, one requiring activation of specific target genes and the other independent of it.

Tumour-proliferative fraction and growth factor expression as markers of tumour response to radiotherapy in cancer of the uterine cervix

This study seeks to define the role of pretreatment of evaluation of tumour growth fraction in cervical cancer and its relationship to the clinical course of the disease. In addition, it also seeks to explain whether cell kinetics and growth factor expression have an association with tumour response to radiotherapy and hence could be of value in the management of patients. All pre-treatment biopsies were analysed for the tumour-proliferative compartment by evaluation of Ki67 antigen expression and argyrophilic nucleolar organiser region (AgNOR) counts. Growth factor analysis was done by analysing for expression of epidermal growth factor (EGF), epidermal growth factor receptor (EGF-R) and transforming growth factors alpha and beta (TGFalpha, TGFbeta). A total of 152 patients were evaluated and a correlation obtained between pre-treatment status of the tumour-growth-fraction-associated markers and clinical outcome following radiotherapy. Such patients were either disease-free (group 1, n=106) or with residual/recurrent disease (group 2, n=46) at a 16-month follow-up. Pre-treatment analysis of AgNOR significantly correlated to disease status after treatment (r=-0.517, P=0.0000). This may be due to an effect of cell proliferation. Lower AgNOR counts were significantly associated with recurrent/residual tumours, suggesting that increased proliferative activity may be a positive prognostic indicator. Similar results were also obtained for the other proliferation-associated marker Ki67 (r=-0.443, P=0.0000). Expression of EGF and EGF-R also showed significant pre-treatment correlations with the final disease outcome (r=0.248, P=0.031 and r=0.503, P=0.0000 respectively). Both these markers were expressed more by patients belonging to group 2. The opposite was the case for TGFalpha, where patients belonging to group 1 showed higher values (r=0.417, P=0.0001). The other growth factor investigated, TGFbeta, also showed a conspicuous differential expression in the two groups of patients (r=-0.604, P=0.0000). Group 1 patients showed mostly mild to moderate expression while most group 2 patients were negative for the growth factor. It therefore appears that tumours with high AgNOR counts and Ki67 index, along with expression of the two types of transforming growth factor (alpha and beta), responded better to radiotherapy.

Bcl-2 protein and apoptosis in pediatric acute lymphoblastic leukemia

Many chemotherapeutic agents are thought to exert their genotoxic effects through induction of programmed cell death (PCD) (apoptosis) in tumor cells. The bcl-2 is an anti-apoptotic oncoprotein and can confer a survival advantage to tumor cells by preventing apoptosis. Overexpression of bcl-2 may therefore be implicated in resistance to chemotherapy. We studied the significance of bcl-2 expression and the PCD index in pediatric acute lymphoblastic leukemia. Evaluation of bcl-2 by immunocytochemistry and PCD by an enzymatic end labelling technique using biotin-dUTP was carried out in a total of 55 cases and 40 controls. Bcl-2 was found to be expressed in 47% (26/55) of the acute lymphoblastic leukemia cases. The positive cells varied from 0-49% among individual samples. Pre-treatment (spontaneous) apoptosis was observed in 62% (34/55) cases. The mean pre-treatment PCD index was 8.27 1.3%, while the median PCD index was 5. The PCD value for the leukemic samples analyzed were then classified as either high apoptosis values ( 5) and low apoptosis values (<5). PCD index was high in 53% (29/55) and low in 47% (26/55). However, 23% (13/55) of cases did not show presence of either apoptosis or bcl-2. There was no association between clinical and laboratory parameters with the apoptotic index or bcl-2 protein expression. However, evaluation of apoptotic index and bcl-2 expression on day 7 of induction chemotherapy showed a borderline correlation between these markers and initial WBC count, presence of mediastinal mass and hepatosplenomegaly. Follow-up of these patients is being done to look for any association between treatment response and apoptosis.

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.

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.

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.