Frequent alterations in the expression of tumor suppressor genes p16INK4A and pRb in esophageal squamous cell carcinoma in the Indian population

Dysregulation of the Rb pathway in recurrent pleomorphic adenoma of the salivary glands

Pleomorphic adenoma (PA) is the most common salivary gland neoplasm, and while mostly benign, recurrences (RPA) and malignant transformation to carcinoma ex-PA (CXPA) do occur. Cell cycle proteins important in its tumorigenesis have been studied as markers for PA with a high risk of RPA or CXPA. The aim of the present study was to investigate cell cycle markers p-16, cyclin D1, CDK4, E2F, and retinoblastoma (Rb) in this context. Expression of p16, cyclin D1, E2F, CDK4, and Rb was studied by immunohistochemistry in 24 cases of PA, 21 of RPA, and 2 of CXPA. The presence of HPV was assessed by in situ hybridization. Immunostaining for p16 and cyclin D1 was negative or weakly positive in most cases of PA while strongly positive in the majority of RPA and both CXPA cases. Staining for Rb and CDK4 was either negative or weakly positive in PA, RPA, and CXPA. Expression of E2F was stronger in RPA and CXPA than in PA. Nuclear reactivity for HPV was not observed in any case. In conclusion, the strong staining for p16, cyclinD1, and E2F in RPA and CXPA, while weak or negative in PA, suggests that these proteins might be involved in recurrence and malignant transformation of PA.

Stepwise expression of CDKN2A and RB1 proteins in esophageal mucosa from patients at high risk for squamous cell carcinoma

Squamous cell carcinoma of the esophagus is a lethal cancer and carries a poor prognosis because of late diagnosis. Identification of molecular markers may aid early diagnosis. We assessed the expression of CDKN2A/RB1 in the esophageal mucosa and its association with the histology. Esophageal biopsies were collected from 38 patients with no esophageal lesion (group 1), from iodine-negative areas of 108 alcoholics/smokers (group 2), and from tumor and nontumor areas in 41 patients with squamous cell carcinoma (group 3). The histologic diagnosis was compared with immunoexpression of CDKN2A/RB1. In group 1, histology showed normal mucosa/mild esophagitis and no expression of CDKN2A/RB1. In groups 2 and 3, the diagnosis was: normal mucosa (38.4%), esophagitis (44.4%), dysplasia and carcinoma in situ (2.8%), and carcinoma (14.3%). The immunoexpression of CDKN2A/RB1 increased in a stepwise manner from the normal mucosa, to esophagitis, dysplasia/carcinoma in situ, and carcinoma (P<0.01). CDKN2A/RB1 was not expressed in the esophageal mucosa of patients without risk factors. p16/pRb expression increased in a stepwise manner, according to the severity of histologic lesions, in biopsies from patients exposed to risk factors or with carcinoma. Esophageal mucosa exposed to risk factors with the expression of those proteins may be at risk for malignant transformation.

Invasive and prognostic significance of pRB in esophageal squamous cell carcinoma: a meta-analysis

This paper investigates the association between protein retinoblastoma (pRB) loss and the T,N stage and prognosis in esophageal squamous cell carcinomas (ESCCs) using meta-analysis. We conducted a meta-analysis of 16 studies, comprising 1,117 patients to clarify this issue. All the studies searched by the electronic literature PubMed and http://www.KJEBM.com, which had been published during the period from January 1996 to January 2012 according to the inclusion criteria. Summary odds ratios (OR) were calculated using fixed or random-effects models. The summary odds ratios (ORs) for pRB inactive were 0.64 (95% confidence interval [CI]:0.45-0.91, P = 0.01) for T1/T2 versus T3/T4 tumors; summary OR = 0.69 (95% CI:0.51-0.94, P = 0.02) for N0 versus N1 tumors. The association between pRB loss and prognosis was examined in nine studies, and the summary hazard ratio was 1.39 (95% CI:1.11-1.74, P = 0.004). pRB inactive was significant associated with T3/T4 tumors and N1 stage as well as adverse prognosis for ESCCs. It appears warranted to prospectively validate that pRB loss may be used for subdividing the T,N stage evaluation of patients with ESCCs, and these patients may be the preponderant people for individualized treatment or target therapy.

Viral load of HPV 16/18 in esophageal squamous cell carcinoma in three ethnic groups living in Xinjiang Autonomous Region, China

To investigate the viral load of human papillomavirus (HPV) in esophageal squamous cell carcinoma (ESCC) patients from three ethnic groups in Xinjiang. Using Gp5+/Gp6+ consensus primers, the prevalence of HPV DNA was examined in 253 paraffin-embedded ESCC samples. The presence and viral load of HPV 16 and HPV 18 were detected in Kazakhs, Uygurs and Hans using type-specific primers by quantitative real-time PCR (qRT-PCR). Among the 253 ESCC samples, 52 cases were positive for HPV DNA, all the 52 positive cases displayed HPV 16 infection, and six of the 52 cases were co-infected by HPV 16 and 18. HPV 16-positive rate and viral load were higher in lesions, and was inversely correlated with differentiation grades. However, there was no statistic significance among different differentiation grades. Also, there were no significant difference between detection rates of HPV types, viral load and age, gender, ethnic group, and lymph node metastasis. HPV 16 and HPV 18 genotypes could simultaneously be detected in ESCC specimens in three main ethnic groups in Xinjiang. The viral load of HPV 16 is higher in the ESCC lesions, and is inversely correlated with the differentiation grades. These observations reinforce the suggestion that HPV infection may involved in ESCC carcinogenesis; however, high prevalence or viral load of HPV infection does not seem to be related with high incidence of ESCC in Kazakhs, which may be the one element among the multiple risk factors contributing to ESCC.

Prognostic significance of cyclinD1 amplification and the co-alteration of cyclinD1/pRb/ppRb in patients with esophageal squamous cell carcinoma

CyclinD1/pRb/ppRb is one of the most important pathways regulating the cell cycle, and related with the development of many cancers. However, the co-alteration of CyclinD1/pRb/ppRb in esophageal squamous cell carcinomas is less understood. This study aims to analyze the combined prognostic significance of cyclinD1 (CCND1) DNA amplification and the co-alteration of CCND1/pRb/ppRB in patients with esophageal squamous cell carcinoma. CCND1 DNA amplification and the protein expression of CCND1, pRb, and ppRb on 100 tumor specimens and 11 normal tissues were detected using real-time quantitative reverse transcription polymerase chain reaction and immunohistochemistry, respectively. Their prognosis significance was analyzed by Kaplan-Meier method. We found that 41% of the patients had CCND1 DNA amplification, which had a short survival time compared with the patients without CCND1 amplification (25.63 months vs. not reached, P=0.007). The patients with the co-alternation of CCND1(+) /pRb(-) /ppRb(+) protein expression levels have a poorer overall survival than the others (11.4 vs. 43.4 months, P=0.001). Cox regression analysis showed that the co-alternation of CCND1/pRb/ppRb and CyclinD1 amplification were the two most independent prognosis factors of patients with esophageal cancer. These findings suggested that CCND1 amplification and co-alternation of CCND1(+) /pRb(-) /ppRb(+) may play a crucial role in the prognostic evaluation of patients with esophageal cancer, and the patients with CCND1(+) /pRb(-) /ppRb(+) have the worst prognosis in all the patients. The results also indicated that the patients with CCND1 amplification or co-alternation of CyclinD1(+) /pRb(-) /ppRb(+) might be the preponderant people for therapy targeting the CCND1/pRb/ppRb pathway in the future.

Human papillomavirus DNA and P16INK4A expression in concurrent esophageal and gastric cardia cancers

AIM: To investigate the relationship between human papillomavirus (HPV) infection and concurrent esophagus and gastric cardia cancer from the same patient (CC) and examine the significance of P16^INK4A protein expression.

METHODS: Polymerase chain reaction was used to detect the presence of HPV type16 (HPV16). The expression of P16^INK4A protein was detected using immunohistochemistry.

RESULTS: Among the CC specimens, HPV16-DNA was found in eight cases of esophageal squamous cell carcinoma (ESCC) and five cases of gastric cardia adenocarcinoma (GCA), respectively (47% vs 29%), and two of both ESCC and GCA. P16^INK4A was highly expressed in both ESCC and GCA. In the HPV-associated positive CC, higher P16^INK4A expression was observed in the GCA than in the ESCC (75% vs 25%, P < 0.05).

CONCLUSION: HPV16 as a correlated risk factor may play an important role in the development of ESCC and GCA. P16^INK4A may be a screening index in the HPV-associated carcinoma of gastric cardia.

Aberrant promoter methylation and reduced expression of p16 gene in esophageal squamous cell carcinoma from Kashmir valley: a high-risk area

Esophageal squamous cell carcinoma (ESCC) is one of the most prevalent cancer in Jammu and Kashmir region of India and has multi-factorial etiology involving dietary habits, genetic factors, and gene environmental interactions. Inactivation of the p16 gene expression by aberrant promoter methylation plays an important role in the progression of esophageal carcinoma. In the present investigation, we have studied the role of p16 promoter methylation in 69 histopathologically confirmed ESCC tissues and compared it with corresponding normal adjacent tissues for DNA methylation in the CpG island in the p16 promoter region by methylation-specific polymerase chain reaction (MSP) and p16 protein expression by immunoblotting. The results showed loss of p16 expression in 67% (46/69) of tumor tissues compared to only 3% in control tissues (2/69). Promoter methylation was observed in 52% (36/69) of tumor tissues and it gradually increased with the increasing severity of histological grades of the cancer (P = 0.0001). Loss of p16 expression with promoter methylation was observed in 26 of 36 cases (72%). Analysis of patients dietary habits revealed a strong association between promoter methylation and high consumption of hot salted tea (P < 0.05) which is a most favourite drink commonly consumed by Kashmiri people.

Human papillomavirus in esophageal squamous cell carcinoma in Colombia and Chile

AIM: To examine the presence of human papillomavirus (HPV) in esophageal squamous cell carcinoma (ESCC) specimens collected from Colombia and Chile located in the northern and southern ends of the continent, respectively.

METHODS: We examined 47 and 26 formalin-fixed and paraffin-embedded ESCC specimens from Colombia and Chile, respectively. HPV was detected using GP5+/GP6+ primer pair for PCR, and confirmed by Southern blot analysis. Sequencing analysis of L1 region fragment was used to identify HPV genotype. In addition, P16^INK4A protein immunostaining of all the specimens was conducted.

RESULTS: HPV was detected in 21 ESCC specimens (29%). Sequencing analysis of L1 region fragment identified HPV-16 genome in 6 Colombian cases (13%) and in 5 Chilean cases (19%). HPV-18 was detected in 10 cases (21%) in Colombia but not in any Chilean case. Since Chilean ESCC cases had a higher prevalence of HPV-16 (without statistical significance), but a significantly lower prevalence of HPV-18 than in Colombian cases (P = 0.011) even though the two countries have similar ESCC incidence rates, the frequency of HPV-related ESCC may not be strongly affected by risk factors affecting the incidence of ESCC. HPV-16 genome was more frequently detected in p16 positive carcinomas, although the difference was not statistically significant. HPV-18 detection rate did not show any association with p16 expression. Well-differentiated tumors tended to have either HPV-16 or HPV-18 but the association was not statistically significant. HPV genotypes other than HPV-16 or 18 were not detected in either country.

CONCLUSION: HPV-16 and HPV-18 genotypes can be found in ESCC specimens collected from two South American countries. Further studies on the relationship between HPV-16 presence and p16 expression in ESCC would aid understanding of the mechanism underlying the presence of HPV in ESCC.

Molecular aspects of esophageal squamous cell carcinoma carcinogenesis

BACKGROUND

The development of human esophageal cancer is a multistep, progressive process. An early indicator of this process is an increased proliferation of esophageal epithelial cells morphologically including basal cell hyperplasia, dysplasia, carcinoma in situ and advanced esophageal squamous cell carcinoma. The process of tumorigenesis at cellular level is related to disorders of the control of cell proliferation and differentiation and controlled cell death (apoptosis). Most of cancer cells contain genetic alterations related to the control of these processes, including transcription factors and apoptosis related proteins.

AIM

In this review, the current knowledge of the genetic profile of this subtype of esophageal tumor is discussed, focusing on the potential of the development of novel tools for clinical management of esophageal squamous cell carcinoma.

CONCLUSIONS

The advances in the field of molecular biology have let us to deeper our knowledge of the process of carcinogenesis of esophagus. Ideally, this knowledge should be translated in benefits for patients suffering from cancer. Thus, better understanding of molecular alterations during carcinogenesis is expected to improve tumor control and prevention and also may lead to better disease management.

Immunohistochemical expression of retinoblastoma pathway proteins in normal salivary glands and in salivary gland tumours

The expression of G1-phase cell-cycle regulators is commonly deregulated in human malignancies. In the present study, we investigate components of the retinoblastoma (RB) pathway in normal salivary glands (NSG) and in salivary gland tumours (SGT). Samples of NSG, pleomorphic adenoma (PA), adenoid cystic carcinoma (ACC), mucoepidermoid carcinoma (MEC), epithelial-myoepithelial carcinoma (EMC), malignant myoepithelioma (MEM), carcinoma ex pleomorphic adenoma (CEPA), and polymorphous, low-grade adenocarcinoma (PLGA) were examined immunohistochemically using antibodies to cyclin D1, cyclin-dependent kinase 4 (CDK-4), retinoblastoma protein (pRb), CDK inhibitor p16 and transcription factor E2F-1. In normal salivary glands, cyclin D1 and cdk-4 were not expressed in any case while p16 was positively expressed. pRb was abundant and E2F-1 moderately expressed. In tumors, cdk-4 was overexpressed in half of the cases. Most tumour cases showed decreased pRb immunoexpression compared to normal salivary glands. In contrast, expression of p16 and E2F-1 increased. pRb expression was absent in three cases of PA, two of EMC and one of CEPA. One case of MEM and one of PLGA showed no E2F-1 expression. Statistical analyses revealed positive correlations between cyclin D1 and cdk-4, cyclin D1 and E2F-1, cdk-4 and E2F-1, and p16 and E2F-1. The benign and malignant tumours expressed retinoblastoma pathway proteins differently form the normal salivary gland. Our findings suggest that, pRb pathway deregulation in salivary gland neoplasms is unrelated to their biological behaviour.

Salivary duct carcinoma: immunohistochemical profile of an aggressive salivary gland tumour

BACKGROUND

Salivary duct carcinoma (SDC) is considered to be a distinct malignancy of the major salivary glands, because of its highly aggressive behaviour, and the high rate of recurrence, metastasis, and disease related death.

AIMS

To investigate expression of the proteins involved in the retinoblastoma (pRb) and p53 pathways, which control cell cycle progression at the G1/S checkpoint, and also expression of the c-erbB-2 oncoprotein in SDCs.

METHODS

Using a streptavidin-biotin method, five cases of SDC were evaluated immunohistochemically for the presence of cyclin D1, CDK4 (cyclin dependent kinase 4), p16 (CDK2A), pRb (retinoblastoma protein), E2F-1, p53, mdm2 (murine double minute 2), bcl-2, and the c-erbB-2 oncoprotein to determine whether there was a correlation between the expression of these proteins and patient outcome.

RESULTS

All of the cases showed deregulation of the pRb and p53 pathways. Of the five patients analysed, only the patient with longterm survival (10 years) was not positive for c-erbB-2 expression.

CONCLUSIONS

c-erbB-2 overexpression was associated with a poor prognosis. Aggressive behaviour, recurrence, and metastatic potential do not appear to be related to cell cycle deregulation, but seem to be associated with the c-erbB-2 oncoprotein, which is involved in matrix degradation and proteolitic activity, in addition to increases in vessel permeability, endothelial cell growth, proliferation, migration, and differentiation. There was a correlation between c-erbB-2 oncoprotein expression and aggressive behaviour in SDCs.

Transcriptional gene expression profile of human esophageal squamous cell carcinoma

To identify the genes involved in esophageal carcinogenesis, we compared gene expression profiles in esophageal squamous cell carcinoma (ESCC) and matched normal esophageal epithelial tissues. Differential display analysis revealed significant changes in the expression of 26 genes; 21 genes were upregulated and 5 genes were downregulated. The differentially expressed genes included those associated with cellular metabolism, cell structure, transcription, proliferation, apoptosis, signal transduction, complement pathway, and cell-cell adhesion. The differential expression of these genes was confirmed by reverse Northern blot analysis. Reverse transcription PCR analysis of ESCC and matched normal esophageal tissues provided the first evidence that melanoma metastasis clone D (MEMD), a gene similar to oncostatin M receptor beta, and KIAA0471 gene products are upregulated in ESCCs. Intriguingly, KIAA0471, a novel gene product, is upregulated in esophageal tumors showing nodal invasion. Identification of these differentially expressed genes in esophageal tumors adds to the repertoire of genes associated with esophageal carcinogenesis and they may thus serve as potential novel molecular targets for diagnosis and therapy. Further characterization of known and unknown differentially expressed cDNAs identified in this study may provide significant clues for understanding the molecular mechanisms underlying esophageal tumorigenesis.

On the nature of genetic changes required for the development of esophageal cancer

It is clear that genetic mutations are necessary for the development of cancer, but the exact number required is not clear, with estimates ranging from one critical hit (e.g., p53) to dozens or perhaps even hundreds of expression changes (by microarray analysis) or chromosomal aberrations. We have used a mathematical model to estimate the critical number of mutations required for the development of esophageal cancer (EC) and to test for the likelihood of an EC major susceptibility gene. Our results suggest that six or seven mutations are required for the development of EC and that there is no evidence of a major susceptibility gene. This does not exclude the possibility that gene-environment interactions may not confer susceptibility or risk. The gradual accumulation of aberrant gene function also can explain the progression of pathologic states seen in the esophagus, from early dysplasia through mild to severe dysplasia and, finally, to cancer, as illustrated in our model.

Alterations in p53 and pRb pathways and their prognostic significance in oesophageal cancer

The pRb (p16-pRb-cyclin D1) and p53 (p53-MDM2-p21) pathways play a critical role in tumorigenesis. To evaluate which of these cell cycle regulatory proteins are related to patients' prognosis, a comprehensive analysis of alterations in these components was carried out in 100 ESCCs (oesophageal squamous cell carcinoma) using immunohistochemistry and correlated with clinicopathological parameters by univariate analysis. Overexpression of p53, MDM2 and cyclin D1 proteins was observed in 73, 42 and 67% of the cases, respectively, while loss of expression of p21, p16 and pRb was observed in 36, 45 and 75% of the cases, respectively. Multiple logistic regression analysis revealed that loss of p16 immunoreactivity was a significant risk factor for tumour stage (pT) (Odds Ratio (OR)=3.3), whereas the loss of pRb was a significant risk factor for nodal metastasis (pN) (OR=8.8). MDM2 overexpression emerged as the most significant risk factor for distant organ metastasis (pM) (OR=4.6). Of the ESCC patients who underwent oesophagectomy, 50 cases were followed-up for a maximum period of 44 months and median of 16 months. Survival analysis revealed that Cyclin D1 overexpression is an adverse prognosticator for disease-free survival, as well as overall survival, and tumour stage (pT) is an adverse prognosticator for disease-free survival. In conclusion, these data support a model of oesophageal cancer pathogenesis in which both the pRb and p53 pathways are inactivated and suggests an in-depth evaluation of the clinical utility of these putative markers is warranted.