Monoclonality and surface lesion-specific microsatellite alterations in premalignant and malignant neoplasia of uterine cervix: a local field effect of genomic instability and clonal evolution

Mathematical Modeling of Field Cancerization through the Lens of Cancer Behavioral Ecology

Field cancerization is a process in which a normal tissue is replaced with pre-cancerous but histologically normal tissue. This transformed field can give rise to malignancy and contribute to tumor relapse. In this paper, we create a mathematical model of field cancerization from the perspective of cancer behavioral ecology. In our model, field cancerization arises from a breakdown in signaling integrity and control, and investigate implications for acute wounding, chronic wounding, aging, and therapeutic interventions. We find that restoration of communication networks can lead to cancer regression in the context of acute injury. Conversely, long term loss of controls, such as through chronic wounding or aging, can promote oncogenesis. These results are paralleled in therapeutic interventions: those that simply target cells in cancerous states may be less effective than those that reestablish signaling integrity. Viewing cancer as a corruption of communication systems rather than as a corruption of individual cells may lead to novel approaches for understanding and treating this disease.

A computational model for the cancer field effect

Introduction

The Cancer Field Effect describes an area of pre-cancerous cells that results from continued exposure to carcinogens. Cells in the cancer field can easily develop into cancer. Removal of the main tumor mass might leave the cancer field behind, increasing risk of recurrence.

Methods

The model we propose for the cancer field effect is a hybrid cellular automaton (CA), which includes a multi-layer perceptron (MLP) to compute the effects of the carcinogens on the gene expression of the genes related to cancer development. We use carcinogen interactions that are typically associated with smoking and alcohol consumption and their effect on cancer fields of the tongue.

Results

Using simulations we support the understanding that tobacco smoking is a potent carcinogen, which can be reinforced by alcohol consumption. The effect of alcohol alone is significantly less than the effect of tobacco. We further observe that pairing tumor excision with field removal delays recurrence compared to tumor excision alone. We track cell lineages and find that, in most cases, a polyclonal field develops, where the number of distinct cell lineages decreases over time as some lineages become dominant over others. Finally, we find tumor masses rarely form via monoclonal origin.

CD8+ T cell exhaustion and cancer immunotherapy

Immunotherapy plays an increasingly important role in the treatment of most malignant tumors, and CD8⁺ T cells are the most important antitumor effector cells in the process of immunotherapy, and their number and functional status largely determine the antitumor effect. However, under continuous antigen exposure and the stimulation of inflammatory factors, CD8⁺ T cells gradually show a weakened proliferation and effector function, accompanied by the expression of a variety of inhibitory receptors. This state is known as CD8⁺ T cell "exhaustion" and often leads to the loss of control and progression of tumors. Recent studies provided us a better understanding of the mechanisms of T cell exhaustion, this review provides an overview of the activation, exhaustion mechanisms and exhaustion characteristics of CD8⁺ T cells. Although immunotherapy can reverse the exhaustion of CD8⁺ T cells and significantly improve the antitumor effects, single immunotherapy often has limitations, and it is difficult to achieve satisfactory antitumor effects, therefore, this review also summarizes up-to-date information related to cancer immunotherapy, and these emerging insights provide promising clues to the future management of malignant tumors.

Early development of esophageal squamous cell cancer: Stem cells, cellular origins and early clone evolution

Esophageal squamous cell carcinoma (ESCC), a highly malignant cancer with poor prognosis, is an example of the classical view of cancer development based on stem cell origin and multistep progression. In the past five years, the applications of large-scale sequencing and single-cell sequencing have expanded to human esophageal normal tissues and precancerous lesions, which, coupled with the application of transgenic lineage tracing technology in mouse models, has provided a more comprehensive and detailed understanding of esophageal stem cell heterogeneity and early clonal evolution of ESCC. In this review, we discuss the heterogeneity of esophageal basal-layer stem cells and their potential relationship with cells of ESCC origin. We present evidence that expansion of NOTCH1 mutants may call into play an evolutionarily conserved anti-cancer mechanism and mold the model of early clonal evolution in ESCCs. Finally, we discuss the potential avenues in this context. This review provides a focused understanding of the early development of ESCC, as a background for early tumor detection, intervention, and prevention strategies.

Predictive Value of Pin1 in Cervical Low-Grade Squamous Intraepithelial Lesions and Inhibition of Pin1 Exerts Potent Anticancer Activity against Human Cervical Cancer

Many oncogenes are involved in the progression from low-grade squamous intraepithelial lesions (LSILs) to high-grade squamous intraepithelial lesions (HSILs); which greatly increases the risk of cervical cancer (CC). Thus, a reliable biomarker for risk classification of LSILs is urgently needed. The prolyl isomerase Pin1 is overexpressed in many cancers and contributes significantly to tumour initiation and progression. Therefore, it is important to assess the effects of cancer therapies that target Pin1. In our study, we demonstrated that Pin1 may serve as a biomarker for LSIL disease progression and may constitute a novel therapeutic target for CC. We used a the novel Pin1 inhibitor KPT-6566, which is able to covalently bind to Pin1 and selectively target it for degradation. The results of our investigation revealed that the downregulation of Pin1 by shRNA or KPT-6566 inhibited the growth of human cervical cancer cells (CCCs). We also discovered that the use of KPT-6566 is a novel approach to enhance the therapeutic efficacy of cisplatin (DDP) against CCCs in vitro and in vivo. We showed that KPT-6566-mediated inhibition of Pin1 blocked multiple cancer-driving pathways simultaneously in CCCs. Furthermore, targeted Pin1 treatment suppressed the metastasis and invasion of human CCCs, and downregulation of Pin1 reversed the epithelial-mesenchymal transition (EMT) of CCCs via the c-Jun/slug pathway. Collectively, we showed that Pin1 may be a marker for the risk of progression to HSIL and that inhibition of Pin1 has anticancer effects against CC.

Unraveling cancer lineage drivers in squamous cell carcinomas

Cancer hijacks embryonic development and adult wound repair mechanisms to fuel malignancy. Cancer frequently originates from de-regulated adult stem cells or progenitors, which are otherwise essential units for postnatal tissue remodeling and repair. Cancer genomics studies have revealed convergence of multiple cancers across organ sites, including squamous cell carcinomas (SCCs), a common group of cancers arising from the head and neck, esophagus, lung, cervix and skin. In this review, we summarize our current knowledge on the molecular drivers of SCCs, including these five major organ sites. We especially focus our discussion on lineage dependent driver genes and pathways, in the context of squamous development and stratification. We then use skin as a model to discuss the notion of field cancerization during SCC carcinogenesis, and cancer as a wound that never heals. Finally, we turn to the idea of context dependency widely observed in cancer driver genes, and outline literature support and possible explanations for their lineage specific functions. Through these discussions, we aim to provide an up-to-date summary of molecular mechanisms driving tumor plasticity in squamous cancers. Such basic knowledge will be helpful to inform the clinics for better stratifying cancer patients, revealing novel drug targets and providing effective treatment options.

Epigenetics of oral and oropharyngeal cancers

Oral and oropharyngeal cancers represent the two most common malignancies of the head and neck region. The major risk factors for these cancers include alcohol consumption, tobacco use (via smoking or chewing) and high-risk human papillomavirus infection. The transition from normal epithelium to premalignant tissue and finally carcinoma is in part caused by a summation of genetic and epigenetic modifications. Epigenetic refers to modifications in the way the genome is expressed in cells. The most common examples of epigenetic control of gene expression are DNA methylation, histone modification and regulation by small non-coding RNAs. The aim of the current paper was to review the recent studies on the main epigenetic changes that have been suggested to serve a role in the carcinogenesis process and progression of oral and oropharyngeal cancers. Furthermore, it is discussed how the epigenetic changes may be used as potential predictive biomarkers and how recent findings in the field may impact the personalized cancer therapy approach for these tumors.

Stretching the limits: from homeostasis to stem cell plasticity in wound healing and cancer

Stem cells (SCs) govern tissue homeostasis and wound repair. They reside within niches, the special microenvironments within tissues that control SC lineage outputs. Upon injury or stress, new signals emanating from damaged tissue can divert nearby cells into adopting behaviours that are not part of their homeostatic repertoire. This behaviour, known as SC plasticity, typically resolves as wounds heal. However, in cancer, it can endure. Recent studies have yielded insights into the orchestrators of maintenance and lineage commitment for SCs belonging to three mammalian tissues: the haematopoietic system, the skin epithelium and the intestinal epithelium. We delineate the multifactorial determinants and general principles underlying the remarkable facets of SC plasticity, which lend promise for regenerative medicine and cancer therapeutics.

Precancer in ulcerative colitis: the role of the field effect and its clinical implications

Cumulative evidence indicates that a significant proportion of cancer evolution may occur before the development of histological abnormalities. While recent improvements in DNA sequencing technology have begun to reveal the presence of these early preneoplastic clones, the concept of 'premalignant field' was already introduced by Slaughter more than half a century ago. Also referred to as 'field effect', 'field defect' or 'field cancerization', these terms describe the phenomenon by which molecular alterations develop in normal-appearing tissue and expand to form premalignant patches with the potential to progress to dysplasia and cancer. Field effects have been well-characterized in ulcerative colitis, an inflammatory bowel disease that increases the risk of colorectal cancer. The study of the molecular alterations that define these fields is informative of mechanisms of tumor initiation and progression and has provided potential targets for early cancer detection. Herein, we summarize the current knowledge about the molecular alterations that comprise the field effect in ulcerative colitis and the clinical utility of these fields for cancer screening and prevention.

Melanoma cells undergo aggressive coalescence in a 3D Matrigel model that is repressed by anti-CD44

Using unique computer-assisted 3D reconstruction software, it was previously demonstrated that tumorigenic cell lines derived from breast tumors, when seeded in a 3D Matrigel model, grew as clonal aggregates which, after approximately 100 hours, underwent coalescence mediated by specialized cells, eventually forming a highly structured large spheroid. Non-tumorigenic cells did not undergo coalescence. Because histological sections of melanomas forming in patients suggest that melanoma cells migrate and coalesce to form tumors, we tested whether they also underwent coalescence in a 3D Matrigel model. Melanoma cells exiting fragments of three independent melanomas or from secondary cultures derived from them, and cells from the melanoma line HTB-66, all underwent coalescence mediated by specialized cells in the 3D model. Normal melanocytes did not. However, coalescence of melanoma cells differed from that of breast-derived tumorigenic cell lines in that they 1) coalesced immediately, 2) underwent coalescence as individual cells as well as aggregates, 3) underwent coalescence far faster and 4) ultimately formed long, flat, fenestrated aggregates that were extremely dynamic. A screen of 51 purified monoclonal antibodies (mAbs) targeting cell surface-associated molecules revealed that two mAbs, anti-beta 1 integrin/(CD29) and anti-CD44, blocked melanoma cell coalescence. They also blocked coalescence of tumorigenic cells derived from a breast tumor. These results add weight to the commonality of coalescence as a characteristic of tumorigenic cells, as well as the usefulness of the 3D Matrigel model and software for both investigating the mechanisms regulating tumorigenesis and screening for potential anti-tumorigenesis mAbs.

Could field cancerization be interpreted as a biochemical anomaly amplification due to transformed cells?

Field cancerization is a concept used to explain cellular and molecular alterations in tissue associated to neoplasia and cancer. This effect was proposed by Slaughter in order to explain the development of multiple primary tumors and locally recurrent cancer. The particular changes associated with this effect, in each type of cancer, have been detected even at distances greater than 10cm off the tumor, in areas classified as normal by histopathological studies. Early detection of lung, colon, and ovary cancer has been reported by the use of Partial Wave Microscopy Spectroscopy (PWS) and has been explained in terms of the field cancerization effect. Until now, field cancerization has been studied as a field effect and we hypothesize that it can be understood as an amplifying effect of biochemical abnormalities in cells, which leads us to ask the question: Could field cancerization be interpreted as a biochemical anomaly amplification due to transformed cells? We propose this question because the biochemical changes due to field cancerization alter the dynamics of molecules and cells in abnormal tissues in comparison to normal ones, these alterations modify the interaction of intracellular and extracellular medium, as well as cellular movement. We hypothesize that field cancerization when interpreted as an amplification effect can be used for the early detection of cancer by measuring the change of cell dynamics.

Exposure to Bovine Leukemia Virus Is Associated with Breast Cancer: A Case-Control Study

BACKGROUND

Age, reproductive history, hormones, genetics, and lifestyle are known risk factors for breast cancer, but the agents that initiate cellular changes from normal to malignant are not understood. We previously detected bovine leukemia virus (BLV), a common oncogenic virus of cattle, in the breast epithelium of humans. The objective of this study was to determine whether the presence of BLV DNA in human mammary epithelium is associated with breast cancer.

METHODS

This was a case-control study of archival formalin fixed paraffin embedded breast tissues from 239 donors, received 2002-2008 from the Cooperative Human Tissue Network. Case definition as breast cancer versus normal (women with no history of breast cancer) was established through medical records and examination of tissues by an anatomical pathologist. Breast exposure to BLV was determined by in situ-PCR detection of a biomarker, BLV DNA, localized within mammary epithelium.

RESULTS

The frequency of BLV DNA in mammary epithelium from women with breast cancer (59%) was significantly higher than in normal controls (29%) (multiply- adjusted odds ratio = 3.07, confidence interval = 1.66-5.69, p = .0004, attributable risk = 37%). In women with premalignant breast changes the frequency of BLV DNA was intermediate (38%) between that of women with breast cancer and normal controls (p for trend < .001).

CONCLUSIONS

Among the specimens in this study, the presence of amplified BLV DNA was significantly associated with breast cancer. The odds ratio magnitude was comparable to those of well-established breast cancer risk factors related to reproductive history, hormones, and lifestyle and was exceeded only by risk factors related to genetics (familial breast cancer), high dose ionizing radiation, and age. These findings have the potential for primary and secondary prevention of breast cancer.

Etiologic field effect: reappraisal of the field effect concept in cancer predisposition and progression

The term 'field effect' (also known as field defect, field cancerization, or field carcinogenesis) has been used to describe a field of cellular and molecular alteration, which predisposes to the development of neoplasms within that territory. We explore an expanded, integrative concept, 'etiologic field effect', which asserts that various etiologic factors (the exposome including dietary, lifestyle, environmental, microbial, hormonal, and genetic factors) and their interactions (the interactome) contribute to a tissue microenvironmental milieu that constitutes a 'field of susceptibility' to neoplasia initiation, evolution, and progression. Importantly, etiological fields predate the acquisition of molecular aberrations commonly considered to indicate presence of filed effect. Inspired by molecular pathological epidemiology (MPE) research, which examines the influence of etiologic factors on cellular and molecular alterations during disease course, an etiologically focused approach to field effect can: (1) broaden the horizons of our inquiry into cancer susceptibility and progression at molecular, cellular, and environmental levels, during all stages of tumor evolution; (2) embrace host-environment-tumor interactions (including gene-environment interactions) occurring in the tumor microenvironment; and, (3) help explain intriguing observations, such as shared molecular features between bilateral primary breast carcinomas, and between synchronous colorectal cancers, where similar molecular changes are absent from intervening normal colon. MPE research has identified a number of endogenous and environmental exposures which can influence not only molecular signatures in the genome, epigenome, transcriptome, proteome, metabolome and interactome, but also host immunity and tumor behavior. We anticipate that future technological advances will allow the development of in vivo biosensors capable of detecting and quantifying 'etiologic field effect' as abnormal network pathology patterns of cellular and microenvironmental responses to endogenous and exogenous exposures. Through an 'etiologic field effect' paradigm, and holistic systems pathology (systems biology) approaches to cancer biology, we can improve personalized prevention and treatment strategies for precision medicine.

Epigenetic alterations in bladder cancer and their potential clinical implications

Urothelial carcinoma (UC), the most common type of bladder cancer, is one of the most expensive malignancies to treat due to its high rate of recurrence. The characterization of the genetic alterations associated with UC has revealed the presence of two mutually exclusive molecular pathways along which distinct genetic abnormalities contribute to the formation of invasive and noninvasive tumors. Here, we focus on the epigenetic alterations found in UC, including the presence of an epigenetic field defect throughout bladders with tumors. A distinct hypomethylation pattern was found in noninvasive tumors, whereas widespread hypermethylation was found in invasive tumors, indicating the two pathways given rise to two tumor types also differ epigenetically. Since certain epigenetic alterations precede histopathological changes, they can serve as excellent markers for the development of diagnostic, prognostic, and surveillance tools. In addition, their dynamic nature and reversibility with pharmacological interventions open new and exciting avenues for therapies. The epigenetic abnormalities associated with UC would make it an excellent target for epigenetic therapy, which is currently approved for the treatment of a few hematological malignancies. Future research is needed to address efficacy and potential toxicity issues before it can be implemented as a therapeutic strategy for solid tumors.

Are viruses associated with human breast cancer? Scrutinizing the molecular evidence

The three viruses most studied as possible causes of human breast cancer are mouse mammary tumor virus-like sequences (MMTV-LS), Epstein-Barr virus (EBV), and oncogenic (high risk) types of human papilloma virus (HPV). The first step in fulfilling traditional criteria for inferring that a cancer is caused by a virus is to demonstrate the virus in the affected tissue. Molecular techniques, compared to host antibody assessment and immunohistochemistry, are the most definitive in establishing viral presence. Results of 85 original molecular research investigations to detect one or more of the three viruses have been extremely divergent with no consensus reached. We evaluated the methodology of these studies for the following: type of molecular assay, DNA/RNA quality control, positive and negative assay controls, type of fixation, genome targets, methods for preventing and detecting molecular contamination, pathology of specimens processed, sample size, and proportion of specimens positive for the viral genome region targeted. Only seven of the studies convincingly demonstrated the presence of an oncogenic virus biomarker (EBV: 4/30 studies (13%); HPV 3/29 studies (10%), whereas 25 convincingly demonstrated absence of the virus studied (MMTV-LS: 4/25 (16%); EBV: 15/30 (50%); 6/29 (21%). The remainder of the studies suffered shortcomings, which, in our opinion, prevented a definitive conclusion. Only one of the studies compared frequency of the virus in breast tissue of breast cancer patients versus appropriate normal control subjects with no history of breast cancer. None of the studies were designed as epidemiologic studies to determine if the presence of the virus was significantly associated with breast cancer. Based on our evaluation, the data in the publications reviewed here remain preliminary, and do not justify a conclusion that MMTV-LS, HPV, or EBV are causally associated with breast cancer. However, they form a valuable basis for redirecting future studies.

Limited evidence of human papillomavirus in [corrected] breast tissue using molecular in situ methods

BACKGROUND

Human papillomavirus (HPV) has been proposed as an etiologic agent of breast cancer based on numerous reports of high-risk (oncogenic) HPV types in malignant breast tissues. However, most of those studies used standard and nested solution polymerase chain reaction (PCR) techniques, both of which are disadvantaged by vulnerability to laboratory contamination from positive control DNA and the inability to localize the signal to a specific cell type. To overcome these drawbacks, the authors of this report explored the use of in situ molecular methods of viral detection to reassess the frequency of HPV in malignant breast tissue.

METHODS

In situ hybridization (ISH) was used with probes that were specific for the capsid region of 12 oncogenic HPV types, and in situ PCR (IS-PCR) was used with primers that were specific for the capsid region of HPV-16, which is the most common oncogenic HPV type. These methods were resistant to molecular contamination and allowed identification of the positive cell type. The specimens examined were malignant tissues from patients with 70 breast cancer patients at The University of Texas M. D. Anderson Cancer Center in Houston, Texas.

RESULTS

HPV was observed in 4 of 70 specimens (5.7%) using ISH and in 2 of 70 specimens (2.9%) of specimens using IS-PCR. Concordance between the 2 methods was high for negative specimens; both methods yielded negative results in 66 of 70 specimens (94.3%). However, there was no concordance for the few positive specimens, probably because of differences in sensitivity and the targeted HPV types.

CONCLUSIONS

Oncogenic (high-risk) HPV types were present in malignant breast epithelium very infrequently and, thus, may be causative agents of only a relatively small proportion of all breast cancers.

Evidence for field cancerization of the prostate

BACKGROUND

Field cancerization, which is not yet well-characterized in the prostate, occurs when large areas of an organ or tissue surface are affected by a carcinogenic insult, resulting in the development of multi-focal independent premalignant foci and molecular lesions that precede histological change.

METHODS

Herein, we review the cumulative body of evidence concerning field effects in the prostate and critically evaluate the methods available for the identification and validation of field effect biomarkers. Validated biomarkers for field effects have an important role to play as surrogate endpoint biomarkers in Phase II prevention trials and as clinical predictors of cancer in men with negative biopsies.

RESULTS

Thus far, field effects have been identified involving nuclear morphometric changes, gene expression, protein expression, gene promoter methylation, DNA damage and angiogenesis. In addition to comparing cancer-adjacent benign tissue to more distant areas or to "supernormal" tissue from cancer-free organs, investigators can use a nested case-control design for negative biopsies that offers a number of unique advantages.

CONCLUSIONS

True carcinogenic field effects should be distinguished from secondary responses of the microenvironment to a developing tumor, although the latter may still lead to useful clinical prediction tools. Prostate 69: 1470-1479, 2009. (c) 2009 Wiley-Liss, Inc.

Integrated genomic and transcriptional profiling identifies chromosomal loci with altered gene expression in cervical cancer

For a better understanding of the consequences of recurrent chromosomal alterations in cervical carcinomas, we integrated genome-wide chromosomal and transcriptional profiles of 10 squamous cell carcinomas (SCCs), 5 adenocarcinomas (AdCAs) and 6 normal controls. Previous genomic profiling showed that gains at chromosome arms 1q, 3q, and 20q as well as losses at 8q, 10q, 11q, and 13q were common in cervical carcinomas. Altered regions spanned multiple megabases, and the extent to which expression of genes located there is affected remains unclear. Expression analysis of these previously chromosomally profiled carcinomas yielded 83 genes with significantly differential expression between carcinomas and normal epithelium. Application of differential gene locus mapping (DIGMAP) analysis and the array CGH expression integration tool (ACE-it) identified hotspots within large chromosomal alterations in which gene expression was altered as well. Chromosomal gains of the long arms of chromosome 1, 3, and 20 resulted in increased expression of genes located at 1q32.1-32.2, 3q13.32-23, 3q26.32-27.3, and 20q11.21-13.33, whereas a chromosomal loss of 11q22.3-25 was related to decreased expression of genes located in this region. Overexpression of DTX3L, PIK3R4, ATP2C1, and SLC25A36, all located at 3q21.1-23 and identified by DIGMAP, ACE-it or both, was confirmed in an independent validation sample set consisting of 12 SCCs and 13 normal ectocervical samples. In conclusion, integrated chromosomal and transcriptional profiling identified chromosomal hotspots at 1q, 3q, 11q, and 20q with altered gene expression within large commonly altered chromosomal regions in cervical cancer.

Chromosomal gain of 3q and loss of 11q often associated with nodal metastasis in early stage cervical squamous cell carcinoma

BACKGROUND/PURPOSE

Cervical cancer remains a health problem among women worldwide. Delineation of genetic changes is critical to understanding the molecular basis of tumor progression, as well as for identifying genetic markers for early identification of patients at high risk for a poor outcome.

METHODS

To provide comparative genomic hybridization data for cervical squamous cell carcinoma in Taiwan, and to gain further insight into genetic markers associated with lymph node metastasis of this disease, we performed comparative genomic hybridization analysis of 30 consecutive cases of cervical squamous cell carcinoma (24 stage IB and 6 stage IIB).

RESULTS

The results disclosed that higher staged tumors or those with lymph node metastasis had more chromosomal imbalances. The commonly recurrent chromosomal imbalances were gains of 3q (46.7%), 1q (36.7%) and 8q (20.0%) and losses of 11q (36.7%), 3p (33.3%), 6q (23.3%), and 2q (20.0%). The frequencies of these chromosomal imbalances in stage IB and IIB tumors did not differ significantly. However, when compared with tumors without lymph node metastasis, the loss of 11q14-q22 (5/9 vs. 3/21, p = 0.019) and gains of 3q11-q22 and 3q26-qter (6/9 vs. 5/21, p = 0.026) were significantly more prevalent in tumors with lymph node metastasis.

CONCLUSION

The results suggest that certain tumor-associated genes residing on 3q and 11q warrant further investigation to elucidate their role in the progression of this disease.

Clinical implications and utility of field cancerization

Cancer begins with multiple cumulative epigenetic and genetic alterations that sequencially transform a cell, or a group of cells in a particular organ. The early genetic events might lead to clonal expansion of pre-neoplastic daughter cells in a particular tumor field. Subsequent genomic changes in some of these cells drive them towards the malignant phenotype. These transformed cells are diagnosed histopathologically as cancers owing to changes in cell morphology. Conceivably, a population of daughter cells with early genetic changes (without histopathology) remain in the organ, demonstrating the concept of field cancerization. With present technological advancement, including laser capture microdisection and high-throughput genomic technologies, carefully designed studies using appropriate control tissue will enable identification of important molecular signatures in these genetically transformed but histologically normal cells. Such tumor-specific biomarkers should have excellent clinical utility. This review examines the concept of field cancerization in several cancers and its possible utility in four areas of oncology; risk assessment, early cancer detection, monitoring of tumor progression and definition of tumor margins.

Hypermethylation of two consecutive tumor suppressor genes, BLU and RASSF1A, located at 3p21.3 in cervical neoplasias

OBJECTIVES

Although initiated by human papillomavirus (HPV), cervical carcinogenesis demands other cofactors to shape its natural course. Epigenetic effects such as DNA methylation, are considered to contribute to carcinogenesis process.

METHODS

The methylation status of BLU and RASSF1A, as well as the HPV infection status, were assessed in a full spectrum of cervical neoplasia, including 45 low-grade squamous intraepithelial lesions (LSIL), 63 high-grade squamous intraepithelial lesions (HSIL), 107 squamous cell carcinomas (SCC), 23 adenocarcinomas (AC), and 44 normal control tissues.

RESULTS

The BLU was methylated in 76.9% of SCC, 57.4% of HSIL, 20.0% of LSIL and 12.5% of normal tissues (P<0.001). The RASSF1A was methylated in 15% of SCC, 17.5% of HSIL, but not in LSIL or normal tissues (P<0.001). In AC, 43.5% of patients showed BLU methylation and 26.1% RASSF1A methylation, significantly higher than the corresponding control frequencies of 12.5% (P=0.005) and 0% (P=0.001), respectively. There was an insignificant trend toward loss of BLU methylation with advancing clinical stages of SCC (84.8%, 67.7%, and 63.6% in stages I, II, and III/IV, respectively; P=0.08). Patients with LSIL infected with high-risk HPV showed a higher rate of BLU methylation than those without HPV (38.8% vs 9.1%, respectively; P=0.057). The methylation of RASSF1A was inversely related to HPV infection in patients with HSIL/SCC (P=0.003).

CONCLUSIONS

These results suggest that the methylation of BLU and RASSF1A genes is associated with cervical carcinogenesis, which could be clinically important in the future molecular screening of cervical neoplasia.

Second field tumors: a new opportunity for cancer prevention?

Recent molecular genetic studies provide evidence that the majority of, if not all, head and neck squamous cell carcinomas (HNSCCs) develop within a contiguous field of preneoplastic cells. Cells of a field show genetic alterations associated with the process of carcinogenesis. A subclone in a field gives rise to an invasive carcinoma. An important implication of this knowledge is that, after surgery of the initial carcinoma, part of the field may remain in the patient. A field with preneoplastic cells that share genetic alterations with cells of the excised tumor has been detected in the resection margins of at least 25% of patients, indicating that this frequently occurs. Fields can be much larger than the actual carcinoma, sometimes having a diameter >7 cm. When a field remains after resection of the tumor, the risk for another carcinoma, designated as a second field tumor (SFT), is considerably greater. It is important to realize that an SFT develops from preneoplastic cells clonally related to the initial tumor. In this respect, it should be discriminated from a recurrent carcinoma that has developed from minimal residual cancer that was left behind and from a second primary tumor that independently develops from the initial carcinoma. Patients at risk for SFTs belong to a unique patient group for whom intense surveillance is indicated and chemoprevention is an attractive option. The priorities are to identify the patients in whom a remaining field will progress to cancer and to find the genes involved. With this knowledge, highly efficient clinical prevention trials, including those using the local application of therapeutic agents, can be designed. It is important to note that SFTs also may occur after treatment of various other cancers, including those of the bladder, skin, esophagus, lung, cervix, breast, and colon.

Interpreting epithelial cancer biology in the context of stem cells: tumor properties and therapeutic implications

Over 90% of all human neoplasia is derived from epithelia. Significant progress has been made in the identification of stem cells of many epithelia. In general, epithelial stem cells lack differentiation markers, have superior in vivo and in vitro proliferative potential, form clusters in association with a specialized mesenchymal environment (the 'niche'), are located in well-protected and nourished sites, and are slow-cycling and thus can be experimentally identified as 'label-retaining cells'. Stem cells may divide symmetrically giving rise to two identical stem cell progeny. Any stem cells in the niche, which defines the size of the stem cell pool, may be randomly expelled from the niche due to population pressure (the stochastic model). Alternatively, a stem cell may divide asymmetrically yielding one stem cell and one non-stem cell that is destined to exit from the stem cell niche (asymmetric division model). Stem cells separated from their niche lose their stemness, although such a loss may be reversible, becoming 'transit-amplifying cells' that are rapidly proliferating but have a more limited proliferative potential, and can give rise to terminally differentiated cells. The identification of the stem cell subpopulation in a normal epithelium leads to a better understanding of many previously enigmatic properties of an epithelium including the preferential sites of carcinoma formation, as exemplified by the almost exclusive association of corneal epithelial carcinoma with the limbus, the corneal epithelial stem cell zone. Being long-term residents in an epithelium, stem cells are uniquely susceptible to the accumulation of multiple, oncogenic changes giving rise to tumors. The application of the stem cell concept can explain many important carcinoma features including the clonal origin and heterogeneity of tumors, the occasional formation of tumors from the transit amplifying cells or progenitor cells, the formation of precancerous 'patches' and 'fields', the mesenchymal influence on carcinoma formation and behavior, and the plasticity of tumor cells. While the concept of cancer stem cells is extremely useful and it is generally assumed that such cells are derived from normal stem cells, more work is needed to identify and characterize epithelial cancer stem cells, to address their precise relationship with normal stem cells, to study their markers and their proliferative and differentiation properties and to design new therapies that can overcome their unusual resistance to chemotherapy and other conventional tumor modalities.

Immunohistochemical expression of DNA mismatch repair (MMR) system proteins (hMLH1, hMSH2) in cervical preinvasive and invasive lesions

The purpose of our study was to analyze the immunohistochemical expression of two MMR system proteins at different steps of neoplastic progression within the squamous cervical epithelium. We compared cases showing normal histologic appearance with those affected by low and high-grade squamous intraepithelial lesions and invasive cervical carcinoma. We investigated formalin-fixed and paraffin-embedded tissue specimens obtained from 83 selected patients (55 with preinvasive neoplastic lesions and 28 with invasive squamous cervical carcinoma) for the expression of hMSH2 and hMLH1 at the immunohistochemical level. We also included 30 patients with histologically normal cervix as a control group. Epithelial cells of CIN lesions showed a significant increase in the expression of both hMLH1 and hMSH2 proteins compared to non-neoplastic squamous epithelium (p < 0.0001). The cases of invasive carcinoma showed a positivity for hMLH1 protein that was statistically lower than that for non-neoplastic cells (p = 0.0009) and that for cases with CIN (p < 0.0001). Positivity for hMSH2 protein was higher than that for normal epithelium (p = 0.0007), but lower than that for preinvasive lesions (p = 0.0001). Preinvasive lesions showed increased expression of both proteins if compared with normal esocervical epithelium. Neoplastic stromal invasiveness is associated with a significant loss of hMLH1 function.

Genomic imbalances in 70 snap-frozen cervical squamous intraepithelial lesions: associations with lesion grade, state of the HPV16 E2 gene and clinical outcome

Host genomic abnormalities may determine the natural history of cervical squamous intraepithelial lesions (SILs). We undertook comparative genomic hybridisation analysis of epithelium carefully microdissected from 70 cervical SILs, the largest series to date. In contrast to previous studies, we used frozen sections for optimal DNA quality and examined whether patterns of DNA copy number imbalance (CNI) are characteristic of SIL grade, human papillomavirus (HPV) status and postoperative recurrence. We identified more CNIs in cervical SIL than previously described, with more CNIs per case in high-grade squamous intraepithelial lesion (HG-SIL) than in low-grade squamous intraepithelial lesion (LG-SIL) (P=0.04). While some CNIs were seen at similar frequencies in HG-SIL and LG-SIL, others, including gain on 1q, 3q and 16q, were found frequently in HG-SIL but not in LG-SIL. There were significantly more CNIs per case in HG-SILs showing loss of the HPV16 E2 gene (a repressor of viral oncogene transcription) (P=0.026) and in HG-SILs that subsequently recurred (P=0.04). Our data are consistent with sequential acquisition of CNIs in cervical SIL progression. Higher frequency of CNI in association with E2 gene loss supports in vitro evidence that high-risk HPV integration is associated with genomic instability. Further investigation of the clinical value of specific host genomic abnormalities in cervical SIL is warranted.

Genomic instability in histologically normal breast tissues: implications for carcinogenesis

Breast cancer is an important contributor to morbidity and mortality in society, but factors that affect the cause of the disease are poorly defined. Genomic instability drives tumorigenic processes in invasive carcinomas and premalignant breast lesions, and might promote the accumulation of genetic alterations in apparently normal tissues before histological abnormalities are detectable. Evidence suggests that genomic changes in breast parenchyma affect the behaviour of epithelial cells, and ultimately might affect tumour growth and progression. Inherent instability in genes that maintain genomic integrity, as well as exogenous chemicals and environmental pollutants, have been implicated in breast-cancer development. Although molecular mechanisms of tumorigenesis are unclear at present, carcinogenic agents could contribute to fields of genomic instability localised to specific areas of the breast. Understanding the functional importance of genomic instability in early carcinogenesis has important implications for improvement of diagnostic and treatment strategies.

Outer breast quadrants demonstrate increased levels of genomic instability

BACKGROUND

Theory holds that the upper outer quadrant of the breast develops more malignancies because of increased tissue volume. This study evaluated genomic patterns of loss of heterozygosity (LOH) and allelic imbalance (AI) in non-neoplastic tissues from quadrants of diseased breasts following mastectomy to characterize relationships between genomic instability and the propensity for tumor development.

METHODS

Tissues from breast quadrants were collected from 21 patients with various stages of breast carcinoma. DNA was isolated from non-neoplastic tissues using standard methods and 26 chromosomal regions commonly deleted in breast cancer were examined to assess genomic instability.

RESULTS

Genomic instability was observed in breast quadrants from patients with ductal carcinomas in situ and advanced carcinomas. Levels of instability by quadrant were not predictive of primary tumor location (P =.363), but outer quadrants demonstrated significantly higher levels of genomic instability than did inner quadrants (P =.017). Marker D8S511 on chromosome 8p22-21.3, one of the most frequently altered chromosomal regions in breast cancer, showed a significantly higher level of instability (P =.039) in outer compared with inner quadrants.

CONCLUSIONS

Non-neoplastic breast tissues often harbor genetic changes that can be important to understanding the local breast environment within which cancer develops. Greater genomic instability in outer quadrants can partially explain the propensity for breast cancers to develop there, rather than simple volume-related concepts. Patterns of field cancerization in the breast appear to be complex and are not a simple function of distance from a developing tumor.

KAI1/CD82 protein expression in primary prostate cancer and in BPH associated with cancer

Current prognostic methods in primary prostate cancer cannot accurately identify patients with clinically significant disease at highest risk of developing metastases. This study examined KAI1/CD82 metastasis suppressor expression by quantitative immunohistochemical analysis of benign prostatic hyperplasia (BPH) and prostate cancer specimens. Altogether, prostate cancers exhibited significant KAI1 overexpression compared to BPH not associated with cancer (P = 0.022). Increased KAI1 expression in well and moderately differentiated cancers, above levels seen in BPH, with decreased expression in poorly differentiated cancers was observed. Interestingly, KAI1 expression in BPH associated with cancers was significantly higher than in BPH not associated with cancer (P = 0.009). Thus, KAI1 overexpression may restrain onset and early stage prostate cancer development, whilst its loss may predispose the patient to more aggressive cancer behaviour. Altered KAI1 expression in prostate cancers and BPH associated with cancer may have important diagnostic roles.

A research-based tumor tissue bank of gynecologic oncology: characteristics of nucleic acids extracted from normal and tumor tissues from different sites

This article describes a gynecology and pathology-oriented tumor tissue bank that is approaching the research requirements of modern molecular oncology and compared characteristics of nucleic acids extracted from preserved tissues. Through August 2000, 8869 specimens, including fresh neoplastic tissues and normal counterparts, body fluids (ascites, tumor content, and blood), and cervical scrapings, were procured from 1853 patients. DNA and RNA were extracted from a random sampling of normal (n = 50) and tumor (n = 53) tissues from the uterine cervix (n = 47), endometrium (n = 24), and ovary (n = 32). As expected, tumor tissues conferred a higher yield of DNA (1.56 +/- 1.24 versus 0.94 +/- 0.72 microg/mg tissue, P = 0.001) and RNA (5.04 +/- 6.21 versus 2.12 +/- 1.76 microg/ml, P < 0.001) than normal tissues. However, the RNA message abundance, as measured by RNA yield/DNA yield, was not different between tumor and normal tissues. With a similar content of DNA in the endometrium, uterine cervix, and ovary, RNA yield was higher in the endometrium than the others (P = 0.013). In tumors from these three sites, similar yields of DNA and RNA were noted. Overall the yield of DNA remained unchanged from specimens preserved for as long as 7 years, although at this length of storage, RNA yield became lower and variable. This study provides the basic characteristics of nucleic acids derived from normal and tumor tissues and ensures future research utility of these frozen specimens.

Frequent loss of heterozygosity in chromosomal region 9pter-p13 in tumor biopsies and cytological material of uterine cervical cancer

Using polymerase chain reaction-based microsatellite analysis we examined 40 cases, tumor biopsies and cytological material, of early stage cervical cancer and 20 healthy donors. Loss of heterozygosity (LOH) was detected in 35 out of 40 cases (87.5%), located on 9pter-p13 (67.5%), 9q32-34 (17.5%), 13q12 (32.5%), 17p13 (0%) and 17q11-q22 (12.5%). Microsatellite instability (MIN) phenotype was found in three out of 40 cases (7.5%). The accuracy in LOH and MIN detection in cytological material compared to tumor biopsies was 91.5 and 86.0%, respectively. None of the specimens of healthy donors exhibited any genetic alteration. Our data suggest that microsatellite analysis in cytological material could be used for the early detection of cervical cancer.

High frequency of loss of heterozygosity in vulval intraepithelial neoplasia (VIN) is associated with invasive vulval squamous cell carcinoma (VSCC)

Vulval intraepithelial neoplasia (VIN) is thought to be the premalignant phase of human papillomavirus (HPV)-associated vulval squamous cell carcinoma (VSCC). Various molecular events have been suggested as markers for progression from VIN to VSCC, but loss of heterozygosity (LOH) in vulval neoplasia has rarely been studied in this context. We performed LOH analysis by polymerase chain reaction (PCR) amplification of polymorphic microsatellite markers at 6 chromosomal loci (17p13-p53, 9p21-p16, 3p25, 4q21, 5p14 and 11p15). The presence of HPV was assessed using consensus PCR primers and DNA sequencing. To examine any association between LOH and the presence of invasive disease, we analyzed 43 cases of lone VIN III, 42 cases of lone VSCC and 21 cases of VIN with concurrent VSCC. HPV DNA was detected in 95% of lone VIN III samples and 71% of lone VSCC samples. Fractional regional allelic loss (FRL) in VIN associated with VSCC was higher than in lone VIN (mean FRL 0.43 vs. 0.21, p < 0.005). LOH at 3p25 occurred significantly more frequently in HPV-negative VSCC than in HPV-positive VSCC (58% vs. 22%, p < 0.04). These data suggest that genetic instability in VIN, reflected by LOH, may increase the risk of invasion. In addition, molecular events differ in HPV-positive and -negative VSCC and 3p25 may be the site of a tumor suppressor gene involved in HPV-independent vulval carcinogenesis.

The significance of human papillomavirus viral load in prediction of histologic severity and size of squamous intraepithelial lesions of uterine cervix

OBJECTIVES

Persistence of high-risk types of human papillomavirus (HPV) in cervical scrapes is responsible for the development, maintenance, and progression of squamous intraepithelial lesions (SILs). Previous studies of viral load and histologic severity have ended with controversial results. This study evaluated the relationships of HPV viral load with size and histologic severity of cervical lesions, which has not been reported previously.

METHODS

By using Hybrid Capture II, DNA level of high-risk HPVs was determined in cervical scrapes and correlated with lesion size and histologic confirmation for 73 women referred for colposcopy. The lesion size was classified as nonvisible (n = 12), small (< or =2/5 of the 12x colposcopic visual filed, n = 36), and large (>2/5 of the 12x field, n = 25) lesions. The final disease status was categorized as high-grade SIL (HSIL)/squamous cell carcinoma (SCC) (designated HSIL+) (n = 32), low-grade SIL (LSIL) (n = 19), and no detectable SIL (n = 22).

RESULTS

A distinct upward trend of high-risk HPV DNA levels paralleled increasing size and histologic severity of cervical lesions (P = 0.003 and 0.001, respectively). With respect to relative risk, women who had high viral load of HPV were at significantly greater risk for large lesion size (odds ratio [OR] = 5.3, 95% confidence interval [CI] = 1.1-24.9) and HSIL+ (OR = 35.0, 95% CI = 4.2-294.5). Of particular note, the risk of developing large lesion size and HSIL+ significantly increased with increasing viral load of HPV (P values for trend test were 0.008 and 0.0004, respectively). In contrast, there were no significant associations of trend in viral load with risk in small lesion size and LSIL.

CONCLUSIONS

The present study revealed that the effect of HPV infection on SIL development is highly influenced by high viral load and highlighted a potential application of viral load testing in predicting the size and severity of lesions of the uterine cervix.

Microsatellite alterations in exfoliated cervical epithelia deoxyribonucleic acid as a marker for high-grade dysplasia

OBJECTIVE

The purpose of this study was to evaluate the feasibility of the use of deoxyribonucleic acid microsatellite alterations in cervical epithelia in the prediction of high-grade dysplasia and to compare it with a strategy based on human papillomavirus testing.

STUDY DESIGN

Our prospective study subjects were from a cohort of 498 women with minimally abnormal Papanicolaou test results including atypical squamous cells of undetermined significance and low-grade squamous intraepithelial lesion who had documented repeated Papanicolaou and human papillomavirus tests. Of these, 52 eligible patients having conizations or hysterectomies as their histologic outcomes were subjected to tests of loss of heterozygosity on a panel of 5 microsatellites (D3S1110, THRB, D3S1228, D6S291, D3S1289) within the deoxyribonucleic acid of exfoliated cervical epithelia. These genetic alterations were analyzed through fluorescence polymerase chain reaction by comparison of allele ratios of exfoliated cells with those of normal control tissue. Predictive values for high-grade cervical dysplasia and cancer between this deoxyribonucleic acid marker and human papillomavirus status were compared.

RESULTS

With the use of loss of heterozygosity in at least one locus for predicting high-grade cervical neoplastic lesion, the sensitivity, specificity, positive predictive value, and negative predictive value were 96.7%, 59.1%, 76.3%, and 92.9%, which were superior to those of the human papillomavirus test (80%, 59.1%, 72.7%, and 92.9%). As a triage for atypical squamous cells of undetermined significance, its sensitivity and negative predictive value were up to 100%.

CONCLUSION

The promising results on determining microsatellite alteration in dysplastic lesions might imply that it is possible to detect the earliest changes by potential molecular markers with exfoliated cervical epithelial cells.

Human papillomavirus infections: epidemiology, pathogenesis, and therapy

BACKGROUND

Human papillomaviruses (HPV) are common human pathogens and are classified into more than 80 different types. These viruses produce benign warts in many cases and aggressive squamous cell carcinomas in other cases.

OBJECTIVE

The goal of this review is to update the reader on the epidemiology, pathogenesis, and therapy of HPV infections. Nonanogenital warts are transmitted by skin-to-skin contact while anogenital warts are usually transmitted sexually. Both types of warts produce much morbidity but rarely undergo malignant transformation. They are commonly treated with surgical or cytodestructive therapy, but immunomodulatory agents, such as imiquimod, have been proven to be very effective in anogenital warts and are being evaluated in nonanogenital warts. Other types of HPV have marked oncogenic potential such that over 99% of all cervical cancers and over 50% of other anogenital cancers are due to infection with oncogenic HPV. Many cofactors, such as cigarette smoking, genetics, and helper viruses, have potential roles in HPV oncogenesis, but their relative contributions are poorly understood. Other control measures for warts and HPV-associated cancers are under study, but the greatest future potential may be from the development of prophylactic and therapeutic vaccines.

CONCLUSIONS

Infection with HPV is very prevalent as are the clinical manifestations of this family of pathogens. Improved therapies for warts (e.g., imiquimod) have recently become available. Vaccines for HPV offer hope for future interventions for warts as well as for prevention of anogenital malignancies.

Microsatellite instability is a late event in the carcinogenesis of uterine cervical cancer

OBJECTIVE

The purpose of this study was to elucidate the role of genetic instability and LOH in the progression of cervical cancer and also to analyze for correlations between these genetic abnormalities and the clinicopathological characteristics of cervical cancers.

METHODS

Seventy-two DNA samples were obtained from 29 carcinoma in situ, 8 microinvasive carcinoma, and 35 invasive cancers. Seven highly polymorphic microsatellite markers representing the chromosome 3p, 6p, and 6q arms were examined by PCR amplification.

RESULTS

Microsatellite instability was detected in 8 of 35 (22.9%) invasive cancers and in 1 of 37 (2.7%) early stage cancers (microinvasive cancer and carcinoma in situ). The incidence of MI was statistically higher in invasive cancers (P < 0.02). On the other hand, loss of heterozygosity (LOH) of chromosome 3p was identified in 6/41 (14.6%) invasive cancers and in 3/27 (11.1%) carcinomas in situ. There was no statistical difference between the two groups. There were no significant correlations between the presence of MI or 3p LOH and clinicopathological characteristics including the histological type, FIGO stage, depth of myometrial invasion, lymphovascular involvement, lymph node metastasis, and recurrence.

CONCLUSION

Our results indicate that genomic instability is a late event during the carcinogenesis of cervical cancer and is associated with the conversion of cervical intraepithelial neoplasia to an invasive phenotype. To the contrary, LOH of chromosome 3p plays an early role in the development of cervical intraepithelial neoplasia. No significant correlation was observed between the presence of MI or LOH and clinicopathological characteristics.

Loss of heterozygosity at the short arm of chromosome 3 in microdissected cervical intraepithelial neoplasia

Loss of heterozygosity (LOH) is a common genetic finding in many human neoplasms, including cervical cancer. The detection of LOH at specific loci in the precursor of cervical cancer, cervical intraepithelial neoplasia (CIN) may help in elucidating the evolution of this cancer, which has a clearly defined histological premalignant phase. However, molecular genetic investigation of CIN is difficult because many of the lesions are very small and sometimes ill defined topographically. In this study we analyzed eighteen polymorphic microsatellite repeats on chromosome 3p in CINs using a method of primer extension pre-amplification (PEP) for whole genome amplification combined with microdissection. These markers encompass chromosome region 3pter-3p12. LOH at one or more loci was detected in five (33%) out of the 15 informative cases with low grade CIN (CIN 1), while 22 (92%) out of 24 cases with high grade CIN (CIN 2 and 3) (P<0.01). The highest incidence (41%) of LOH was detected at locus D3S1038 (3p26.1-3p25.2). Frequent LOH (more than 20%) was also found at other loci including D3S1110 (3p25.3-3p25.1) (31%), D3S656 (3p25.1) (24%), D3S1076 (3p21.2-3p21.1) (29%), D3S1300 (3p21.1-3p14.2) (24%), D3S1600 (3p14.2-3p14.1) (24%), and D3S1079 (3p13) (25%). The results from this study taken together with others indicate that the genetic alterations on chromosome 3p are common in high grade of CIN and are probably early events in cervical carcinogenesis. Tumor suppressor gene(s) that play a role in cervical neoplasm may be located on the short arm of chromosome 3, likely at or near 3p26.1-25.1, 3p21.2-21.1, and 3p14.2-13.

PIK3CA as an oncogene in cervical cancer

Amplification of chromosome arm 3q is the most consistent aberration in cervical cancer, and is implicated in the progression of dysplastic uterine cervical cells into invasive cancer. The present study employed the 'positional candidate gene' strategy to determine the contribution of PIK3CA, which is located in 3q26.3, in cervical tumorigenesis. PIK3CA is known to be involved in the PI 3-kinase/AKT signaling pathway, which plays an important role in regulating cell growth and apoptosis. The results of comparative genomic hybridization show that the 3q26.3 amplification was the most consistent chromosomal aberration in primary tissues of cervical carcinoma, and a positive correlation between an increased copy number of PIK3CA (detected by competitive PCR) and 3q26.3 amplification was found in tumor tissues and in cervical cancer cell lines. In cervical cancer cell lines harboring amplified PIK3CA, the expression of gene product (p110alpha) of PIK3CA was increased, and was subsequently associated with high kinase activity. In addition, transformation phenotypes in these lines, including increased cell growth and decreased apoptosis, were found to be significantly affected by the treatment of specific PI 3-kinase inhibitor, suggesting that increased expression of PIK3CA in cervical cancer may result in promoting cell proliferation and reducing apoptosis. These evidences support that PIK3CA is an oncogene in cervical cancer and PIK3CA amplification may be linked to cervical tumorigenesis. Oncogene (2000).