Curcumin mediates selective aggregation of mutant p53 in cancer cells: A promising therapeutic strategy

The increased stability of mutant p53 (Mutp53) plays a crucial role in its gain of function, making proteins involved in its stabilization promising targets for drug intervention. Although curcumin is known to exhibit anti-cancer effects, its role as a deubiquitinase (DUB) inhibitor in Mutp53 destabilization remains poorly explored. Our study demonstrates that curcumin treatment induced ubiquitination and destabilization of Mutp53 but not Wild-type p53 (WTp53) in cancer cells. Furthermore, proteasome and lysosome inhibitors failed to reverse the effect of curcumin, indicating Mutp53 destabilization is possibly via an alternate mechanism. Intriguingly, curcumin treatment also resulted in the nuclear aggregation of the Mutp53 protein, which was rescued by combined Dithiothreitol (DTT) treatment. Similar to curcumin, a broad-spectrum deubiquitinase inhibitor induced Mutp53 aggregation implying curcumin possibly acts by inhibiting deubiquitinases. Additionally, curcumin treatment inhibited colony-forming abilities, induced cytoplasmic vacuolation, and cell death selectively in Mutp53-expressing cells. Collectively, our study highlights the potential of curcumin as a promising therapeutic agent for targeting Mutp53-expressing cancer cells.

ΔNp63 overexpression promotes oral cancer cell migration through hyperactivated Activin A signaling

Oral cancer is a common malignant tumor of the oral cavity that affects many countries with a prevalent distribution in the Indian subcontinent, with poor prognosis rate on account of locoregional metastases. Gain-of-function mutations in p53 and overexpression of its related transcription factor, p63 are both widely reported events in oral cancers. However, targeting these alterations remains a far-achieved aim due to lack of knowledge on their downstream signaling pathways. In the present study, we characterize the isoforms of p63 and using knockdown strategy, decipher the functions and oncogenic signaling of p63 in oral cancers. Using Microarray and Chromatin Immunoprecipitation experiments, we decipher a novel transcriptional regulatory axis between p63 and Activin A and establish its functional significance in migration of oral cancer cells. Using an orally bioavailable inhibitor of the Activin A pathway to attenuate oral cancer cell migration and invasion, we further demonstrate the targetability of this signaling axis. Our study highlights the oncogenic role of ΔNp63 - Activin A - SMAD2/3 signaling and provides a basis for targeting this oncogenic pathway in oral cancers.

Elevated translationally controlled tumour protein promotes oral cancer progression and poor outcome

BACKGROUND

Translationally controlled tumour protein (TCTP) is a multifunctional protein elevated in multiple cancers. However, studies on its role in oral carcinogenesis and prognosis are rare. We recently reported the role of its interacting partner, MCL1, in oral cancer progression and outcome. Hence, the present study aimed to assess TCTP expression in oral tumorigenesis and its association with patient outcomes alone and in combination with MCL1.

METHODS

TCTP expression was assessed by immunohistochemistry and immunoblotting in oral tissues and cells, respectively. Cell viability post siRNA/dihydroartemisinin treatment was analysed by tetrazolium salt assay. Cell survival, invasion and tumorigenic potential post TCTP knockdown were assessed by clonogenic, Matrigel and soft-agar assays, respectively. The association of TCTP with patient outcome was analysed by Kaplan-Meier and Cox regression.

RESULTS

TCTP was significantly overexpressed in oral premalignant lesions (p < 0.0001), oral tumours (p < 0.0001) and oral dysplastic and cancer cells versus normal oral mucosa and also in recurrent (p < 0.05) versus non-recurrent oral tumours. Further, elevated TCTP was significantly (p < 0.05) associated with poor recurrence free survival (RFS) and poor overall survival (OS; hazard ratio = 2.29; p < 0.05). Intriguingly, the high co-expression of TCTP and MCL1 further reduced the RFS (p < 0.05) and OS (p < 0.05; hazard-ratio = 3.49; p < 0.05). Additionally, TCTP knockdown decreased survival (p < 0.05), invasion (p < 0.01) and in vitro tumorigenic potential (p < 0.0001). Dihydroartemisinin treatment reduced TCTP levels and viability of oral cancer cells.

CONCLUSION

Our studies demonstrate an oncogenic role of TCTP in oral cancer progression and poor outcome. Thus, TCTP may be a potential prognostic marker and therapeutic target in oral cancers.

Identification of bicyclic compounds that act as dual inhibitors of Bcl-2 and Mcl-1

Elevated expression of anti-apoptotic proteins, such as Bcl-2 and Mcl-1 contributes to poor prognosis and resistance to current treatment modalities in multiple cancers. Here, we report the design, synthesis and characterization of benzimidazole chalcone and flavonoid scaffold-derived bicyclic compounds targeting both Bcl-2 and Mcl-1 by optimizing the structural differences in the binding sites of both these proteins. Initial docking screen of Bcl-2 and Mcl-1 with pro-apoptotic protein Bim revealed possible hits with optimal binding energies. All the optimized bicyclic compounds were screened for their in vitro cytotoxic activity against two oral cancer cell lines (AW8507 and AW13516) which express high levels of Bcl-2 and Mcl-1. Compound 4d from the benzimidazole chalcone series and compound 6d from the flavonoid series exhibited significant cytotoxic activity (IC₅₀ 7.12 μM and 17.18 μM, respectively) against AW13516 cell line. Time Resolved-Fluorescence Resonance Energy Transfer (TR-FRET) analysis further demonstrated that compound 4d and compound 6d could effectively inhibit the Bcl-2 and Mcl-1 proteins by displacing their BH3 binding partners. Both compounds exhibited potent activation of canonical pathway of apoptosis evident from appearance of cleaved Caspase-3 and PARP. Further, treatment of oral cancer cells with the inhibitors induced dissociation of the BH3 only protein Bim from Mcl-1 and Bak from Bcl-2 but failed to release Bax from Bcl-xL thereby confirming the nature of compounds as BH3-mimetics selectively targeting Bcl-2 and Mcl-1. Our study thus identifies bicyclic compounds as promising candidates for anti-apoptotic Bcl-2/Mcl-1 dual inhibitors with a potential for further development.

Myeloid cell leukemia-1: a formidable barrier to anticancer therapeutics and the quest of targeting it

The antiapoptotic B cell lymphoma-2 (Bcl-2) family members are apical regulators of the intrinsic pathway of apoptosis that orchestrate mitochondrial outer membrane permeabilization (MOMP) through interactions with their proapoptotic counterparts. Overexpression of antiapoptotic Bcl-2 family proteins has been linked to therapy resistance and poor prognosis in diverse cancers. Among the antiapoptotic Bcl-2 family members, predominant overexpression of the prosurvival myeloid cell leukemia-1 (Mcl-1) has been reported in a myriad of hematological malignancies and solid tumors, contributing to therapy resistance and poor outcomes, thus making it a potential druggable target. The unique structure of Mcl-1 and its complex regulatory mechanism makes it an adaptive prosurvival switch that ensures tumor cell survival despite therapeutic intervention. This review focusses on diverse mechanisms adopted by tumor cells to maintain sustained elevated levels of Mcl-1 and how high Mcl-1 levels contribute to resistance in conventional as well as targeted therapies. Moreover, recent developments in the Mcl-1-targeted therapeutics and the underlying challenges and considerations in designing novel Mcl-1 inhibitors are also discussed.

Elevated USP9X drives early-to-late-stage oral tumorigenesis via stabilisation of anti-apoptotic MCL-1 protein and impacts outcome in oral cancers

BACKGROUND

Overexpression of anti-apoptotic MCL-1 protein in oral squamous cell carcinoma (OSCC) is linked to disease progression, therapy resistance and poor outcome. Despite its characteristic short half-life owing to ubiquitin-proteasome-dependent degradation, oral tumours frequently show elevated MCL-1 protein expression. Hence, we investigated the role of deubiquitinase USP9X in stabilising MCL-1 protein and its contribution to oral tumorigenesis.

METHODS

Expression of MCL-1 and USP9X was assessed by immunoblotting and immunohistochemistry in oral cancer cell lines and tissues. The association between MCL-1 and USP9X was confirmed by coimmunoprecipitation and immunofluorescence. Cell death assessment was performed by MTT, flow cytometry and clonogenic assays.

RESULTS

Both USP9X and MCL-1 are significantly elevated in oral premalignant lesions and oral tumours versus normal mucosa. USP9X interacts with and deubiquitinates MCL-1, thereby stabilising it. Pharmacological inhibition of USP9X potently induced cell death in OSCC cells in vitro and in vivo. The elevated expression of USP9X and MCL-1 correlated with poor prognosis in OSCC patients.

CONCLUSION

We demonstrate the oncogenic role of USP9X in driving early-to-late stages of oral tumorigenesis via stabilisation of MCL-1, suggesting its potential as a prognostic biomarker and therapeutic target in oral cancers.

Novel nucleolar localization of clusterin and its associated functions in human oral cancers: An in vitro and in silico analysis

Clusterin (CLU), a multifunctional chaperonic glycoprotein associated with diverse cellular functions has been shown to act as an oncogene or tumour suppressor gene in different cancers, implying a dual role in tumorigenesis. Here, we investigated the expression of CLU isoforms, their subcellular localization and functional significance in oral cancer cells. Significant downregulation of secretory CLU (sCLU) transcripts was observed in oral cancer cell lines and tumours versus normal cells while the nuclear CLU (nCLU) transcripts were undetectable. We demonstrated for the first time the nucleolar localization of sCLU, its response to different nucleolar stresses and association with cajal bodies post nucleolar stress. Functionally, knockdown of CLU revealed its negative association with ribosome biogenesis implying a possible tumour suppressor like role in oral cancers. Further, loss of sCLU in these cells also resulted in altered nuclear morphology and shrunken tubulin filaments. In addition, the levels of nucleolar Nucleophosmin 1(NPM1) and Fibrillarin, known to regulate nuclear morphology were downregulated indicating a possible role of sCLU in their stabilization. Further, an in silico docking approach to gain insights into the interaction of sCLU with nucleolar proteins NPM1, Fibrillarin, UBF and Nucleolin, revealed the involvement of a conserved region comprising of amino acid residues 140-155 of sCLU β-chain, specifically via the Phe152 residue in hydrophobic interactions with these client nucleolar proteins indicating a possible stabilizing or regulatory role of sCLU. SIGNIFICANCE OF THE STUDY: This is the first study to demonstrate the nucleolar localization of sCLU and its associated functions in oral cancer cells. Downregulation of sCLU in oral cancer tissues and cell lines, and its negative association with ribogenesis suggest its tumour suppressor like role in oral cancers. The possible role of sCLU in stabilization or regulation of different nucleolar proteins thereby impacting their functions is also implicated.

Human Papillomavirus-Related Multiphenotypic Sinonasal Carcinoma with Unique HPV type 52 Association: A Case Report with Review of Literature

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC) is a recently described distinctive clinicopathologic entity defined by association to high risk HPV, localization to sinonasal tract and close histologic resemblance to salivary gland tumors. Lack of awareness of its pathologic features and biology among pathologists and oncologists make this entity susceptible to misdiagnosis and erroneous management. Herein, we illustrate a case of HMSC of the nasal cavity associated with heretofore unreported subtype HPV-52 and discuss the challenges associated with diagnosis and management of this rare tumor. A 48-year-old woman with intermittent epistaxis for 6 months presented with a nasal mass and underwent middle turbinectomy. Histology showed a tumor with features typical of adenoid cystic carcinoma (ACC) in the form of basaloid cells and cribriform architecture. However, careful inspection revealed findings uncommon in ACC; such as surface pagetoid tumor spread, areas of solid sheets of myoepithelial cells accompanied by increased mitotic figures which prompted immunohistochemistry. Multidirectional differentiation into ductal (CK7, AE1/AE3) and myoepithelial (p63, p40, S100, calponin) lineage together with strong and diffuse immunopositivity for p16 distinguished this tumor from ACC. HPV genotyping was positive for high risk HPV subtype HPV52, which confirmed the diagnosis of HMSC. HPV-related multiphenotypic sinonasal carcinoma is an under-recognized unique clinicopathologic entity that needs awareness to avoid mistaking it for commoner salivary gland tumors. Making accurate diagnosis of this newly-described tumor is imperative in order to understand its biology and to develop optimal therapeutic strategies.

Comparative evaluation of the clonogenic capacity of periodontal ligament fibroblasts in Hank's balanced salt solution and egg albumen: An in vitro study

BACKGROUND/AIM

The type of storage media for short-term storage of an avulsed tooth is a critical determinant for the success of tooth replantation. If immediate replantation of an avulsed tooth is not possible, it is advised to store the tooth in a suitable storage medium. The viability and clonogenicity of periodontal ligament fibroblasts (PDLF) determines the success of replantation of an avulsed tooth. The aim of this study was to evaluate the effect on the clonogenic capacity of PDLF's upon storage in Hank's balanced salt solution (HBSS) and egg albumen.

METHODS

Fibroblast cell culture was established from a human premolar tooth extracted for orthodontic purposes. The PDLF cells thus obtained were treated with either Dulbecco's modified Eagle's medium (DMEM; as a positive control), HBSS, or egg albumen for different durations at room temperature and then allowed to grow in DMEM medium until visible colonies appeared which were then fixed, stained, and scored manually.

RESULTS

With increase in the duration of storage in both egg albumen as well as HBSS, there was a reduction in the clonogenic capacity of the PDLF's as compared to DMEM. However, storage in egg albumen led to a significant reduction in the clonogenic capacity of PDLF's (8%-16% for egg albumen) compared to HBSS (80%-90%).

CONCLUSION

Due to its limited ability to support the clonogenicity of PDLF's, egg albumen is a poor storage medium for an avulsed tooth compared to either DMEM or HBSS.

Human papillomavirus in head and neck cancer in India: Current status and consensus recommendations

Human papillomavirus (HPV) associated head and neck squamous cell cancers (HNSCC) have become increasingly common in the West, but the same cannot be said about India. These cancers have a different biology and confer a better prognosis, however, its current role in the management of patients in India is not clearly defined. At the 35th Indian Cooperative Oncology Network conference held in September 2016, a panel of radiation, surgical and medical oncologists, pathologists, and basic scientists from across the country having experience in clinical research with respect to HPV in HNSCC reviewed the available literature from India. All the ideas and facts were thereafter collated in this report. Various topics of controversy in dealing with the diagnosis and management of HPV-associated HNSCC have been highlighted in this report in context to the Indian scenario. Furthermore, the prevalence of the same and its association with tobacco and high-risk sexual behavior has been touched on. Conclusively, a set of recommendations has been proposed by the panel to guide the practicing oncologists of the country while dealing with HPV-associated HNSCC.

Human papillomavirus/p16 positive head and neck cancer in India: Prevalence, clinical impact, and influence of tobacco use

BACKGROUND

Limited data are available on the prevalence and prognostic significance of human papillomavirus (HPV) in squamous cell carcinoma of head and neck (SCCHN) in the Indian population.

AIM

The present study aimed to determine the prevalence of HPV and p16 in an Indian cohort of SCCHN and assess their correlation and influence of tobacco use on patient outcomes.

MATERIALS AND METHODS

The p16 and HPV status of 170 patients of SCCHN treated with curative chemoradiotherapy was determined using immunohistochemistry and polymerase chain reaction, respectively, and further correlated with their demographic characteristics. In addition, genotyping of HPV-positive samples was performed. Survival outcomes were analyzed and compared for both p16 positive (p16 +ve) and p16 negative (p16 -ve) population. The influence of tobacco use on outcomes was assessed.

RESULTS

p16 expression was observed in 20% (34/170) cases whereas HPV positivity was detected in 39.4% (67/170) of SCCHN patients with HPV16 being the most common (91%) subtype. About 73.5% patients were p16 +ve among the tobacco users in this cohort (83.5%). Interestingly, p16 positivity was significantly associated with nonusers of tobacco (P = 0.02) and younger females (P = 0.06). The p16 +ve and p16 -ve groups did not exhibit a significant difference in the 5-year cause-specific survival (CSS) (79% vs. 72.2%), disease-free survival (DFS) (78.3% vs. 68.3%, P = 0.5), and locoregional control (LRC) (82.2% vs. 71.5%, P = 0.4). However, the outcome analyses in tobacco nonusers revealed a definite large improvement in CSS (P = 0.08) and a trend toward improvement in DFS (P = 0.15) and LRC (P = 0.11) in the p16 +ve versus the p16 -ve groups.

CONCLUSION

The low prevalence of p16 positivity (20%) and dual HPV and p16 positivity (38.8%) in the studied Indian cohort indicates the low utility of p16 as a surrogate for HPV in the background of high tobacco burden. The outcomes are largely improved in a small subset of SCCHN cases comprising p16 +ve tobacco nonusers.

A simple cost-effective modification improves the quality of immunocytochemical staining in cervical scrape samples characterized by presence of excess mucus

Immunocytochemistry (ICC) is a very important tool in a diverse range of biomedical research as well as in diagnostic cytopathology. Smears prepared from cervical scrapes contain a large amount of overlying mucus that interferes with the standard immunocytochemical staining protocol. A modified ICC protocol is described, which involves pretreatment of these smears with 1 mg/ml solution of Ambroxol hydrochloride in methanol for 1 hour. Source of Ambroxol hydrochloride was a 30 mg Mucolite^™ tablet, at a cost of 1.70 rupees (∼3·5 US cents) per tablet. This mucolytic solution effectively clears the mucus, facilitating the accessibility of the antibody to the antigenic determinants. This pretreatment resulted in the increased percentage of positively stained cells as well as staining intensity, leading to improved overall ICC staining and score. This is a novel modification that can be cost-effectively applied in ICC staining protocols for cytology samples characterized by the presence of excess mucus.

Overexpression of Mcl-1L splice variant is associated with poor prognosis and chemoresistance in oral cancers

Background

Altered expression of Mcl-1, an anti-apoptotic member of the Bcl-2 family, has been linked to the progression and outcome of a variety of malignancies. We have previously reported the overexpression of Mcl-1 protein in human oral cancers. The present study aimed to evaluate the clinicopathological significance of the expression of three known Mcl-1 isoforms in oral tumors and the effect of targeting Mcl-1L isoform on chemosensitivity of oral cancer cells.

Methods

The expression of Mcl-1 isoforms- Mcl-1L, Mcl-1S & Mcl-1ES was analyzed in 130 paired oral tumors and 9 oral cell lines using quantitative real-time PCR & protein by western blotting. The Mcl-1 mRNA levels were correlated with clinicopathological parameters and outcome of oral cancer patients. The effect of Mcl-1L shRNA or Obatoclax (a small molecule Mcl-1 inhibitor), in combination with Cisplatin on chemosensitivity of oral cancer cells was also assessed.

Results

Anti-apoptotic Mcl-1L was predominantly expressed, over low or undetectable pro-apoptotic Mcl-1S and Mcl-1ES isoforms. The Mcl-1L transcripts were significantly overexpressed in all cancer cell lines and in 64% oral tumors versus adjacent normals (P<0.02). In oral cancer patients, high Mcl-1L expression was significantly associated with node positivity (P = 0.021), advanced tumor size (P = 0.013) and poor overall survival (P = 0.002). Multivariate analysis indicated Mcl-1L to be an independent prognostic factor for oral cancers (P = 0.037). Mcl-1L shRNA knockdown or its inhibition by Obatoclax in combination with Cisplatin synergistically reduced viability and growth of oral cancer cells than either treatment alone.

Conclusion

Our studies suggest that overexpression of Mcl-1L is associated with poor prognosis and chemoresistance in oral cancers. Mcl-1L is an independent prognostic factor and a potential therapeutic target in oral cancers.

Raman spectroscopic study of radioresistant oral cancer sublines established by fractionated ionizing radiation

Radiotherapy is an important treatment modality for oral cancer. However, development of radioresistance is a major hurdle in the efficacy of radiotherapy in oral cancer patients. Identifying predictors of radioresistance is a challenging task and has met with little success. The aim of the present study was to explore the differential spectral profiles of the established radioresistant sublines and parental oral cancer cell lines by Raman spectroscopy. We have established radioresistant sublines namely, 50Gy-UPCI:SCC029B and 70Gy-UPCI:SCC029B from its parental UPCI:SCC029B cell line, by using clinically admissible 2Gy fractionated ionizing radiation (FIR). The developed radioresistant character was validated by clonogenic cell survival assay and known radioresistance-related protein markers like Mcl-1, Bcl-2, Cox-2 and Survivin. Altered cellular morphology with significant increase (p<0.001) in the number of filopodia in radioresistant cells with respect to parental cells was observed. The Raman spectra of parental UPCI:SCC029B, 50Gy-UPCI:SCC029B and 70Gy-UPCI:SCC029B cells were acquired and spectral features indicate possible differences in biomolecules like proteins, lipids and nucleic acids. Principal component analysis (PCA) provided three clusters corresponding to radioresistant 50Gy, 70Gy-UPCI:SCC029B sublines and parental UPCI:SCC029B cell line with minor overlap, which suggest altered molecular profile acquired by the radioresistant cells due to multiple doses of irradiation. The findings of this study support the potential of Raman spectroscopy in prediction of radioresistance and possibly contribute to better prognosis of oral cancer.

Bcl-xL protein: predictor of complete tumor response in patients with oral cancer treated with curative radiotherapy

BACKGROUND

We earlier observed altered expression of p53 and Bcl-xL in oral cancer cell lines/tissues and wanted to evaluate these proteins for prediction of radiotherapy response and outcome.

METHODS

Thirty-nine paraffin-embedded, pretreatment oral cancer biopsies were analyzed for protein expression using immunohistochemistry and correlated with tumor response to radiotherapy and disease-free survival (DFS).

RESULT

High p53 (p = .040) was observed in female versus male patients. Increased p53 intensity (p = .063) was observed in tobacco habitués (chewers ± smokers) versus patients with no habits. In univariate analysis, nodal positivity (p = .044) and favorable/complete tumor response (p = .002) exhibited a significant correlation with DFS, whereas tumor response emerged as an independent predictor of DFS in multivariate analysis. Significantly high Bcl-xL (p = .048) was observed in the unfavorable versus favorable responders.

CONCLUSION

Our study suggests that Bcl-xL expression along with clinical parameters may be useful for identifying patients with oral cancer likely to draw maximum benefit from curative radiotherapy.

PCNA and anti-apoptotic Mcl-1 proteins predict disease-free survival in oral cancer patients treated with definitive radiotherapy

At our laboratory, we recently observed cell cycle and apoptosis-related proteins Myeloid Cell Leukemia-1 (Mcl-1) and Proliferating Cell Nuclear Antigen (PCNA) to be altered in oral tumours/cell lines. The present study aimed to evaluate the above proteins for predicting response and outcome in oral cancer patients treated with definitive radiotherapy. Pre-treatment oral cancer biopsy samples from 39 patients were examined for Mcl-1 and PCNA proteins using immunohistochemistry and correlated with clinico-pathological variables using disease-free survival (DFS) as the primary endpoint. We observed high expression of Mcl-1 in older versus younger patients (p=0.013) and in tobacco chewers+/-alcohol versus smokers+/-alcohol (p=0.037); and PCNA in node-positive versus node-negative tumours (p=0.037). On univariate analysis, high PCNA (p=0.007), Mcl-1 (p=0.050), node positivity (p=0.040) and co-expression of PCNA and Mcl-1 (p=0.008), had a significant impact on DFS. On multivariate analysis, low PCNA/Mcl-1 (p=0.006) co-expressing tumours were associated with improved DFS. Thus our study suggests that in patients undergoing primary radiotherapy, PCNA could be of potential predictive value to identify patients with risk of nodal metastases and in combination with Mcl-1 may have potential prognostic value to differentiate patients with poor DFS. These markers may be used for future trial patients requiring radiotherapy for their treatment.

Expression of bcl-2 and bax in chewing tobacco-induced oral cancers and oral lesions from India

Deregulation of oncogenes and tumor suppressor genes involved in apoptosis has been associated with tumor development and progression. To investigate the involvement of apoptosis regulating proteins in oral cancer in Indian patients, primarily associated with chewing tobacco habits, immunohistochemical expression of bcl-2 and bax was examined in 63 oral squamous cell carcinomas, and 31 putative premalignant lesions. Our studies revealed overexpression of tumor specific cytoplasmic bcl-2 in 56% and bax in 43% oral cancers. The oral cancers in the Indian patients are preceded by premalignant oral lesions; hence oral lesions were examined for bcl-2 and bax expression. We observed aberrant expression of bcl-2 in 16% oral lesions comprising leukoplakias and SMF and bax in 55% oral lesions. We have already reported, p53 expression in these oral cancers and lesions. It was noteworthy that 30% oral cancers demonstrated a p53+bcl2+ pattern, and 14% samples exhibited p53+bcl2+bax+ pattern. However, none of the oral lesions showed concurrent deregulation of p53 and bcl-2 or all the three genes. Interestingly 45% oral lesions were p53-bax+ as compared to 18% oral cancers; while 39% oral lesions were bcl2-bax+ as compared to 14% oral cancers, indicating overexpression of bax in oral lesions, in the absence of p53 and bcl-2 proteins. Significant correlation was observed between positive nodal status and bcl2+ (p=0.047) and p53+bcl-2+ (p=0.01) in oral cancers. Kaplan Meier survival analysis showed significantly (p=0.059) higher survival in patients with p53- oral tumors than with p53+ tumors. Our studies thus indicate frequent overexpression of apoptosis regulators bcl-2, bax and p53 proteins in oral cancers, and a subset of oral lesions, representing early events in oral car-cinogenesis. The aberrant bcl-2 expression and loss of p53 function observed, may play an important role in the tumorigenesis of oral cancers by allowing escape from apoptosis and enabling additional genetic alterations to accrue.