Reduced expression of p27/Kip1 is associated with the development of pulmonary adenocarcinoma

Expression of cell cycle-related proteins in oropharyngeal squamous cell carcinoma based on human papilloma virus status

The molecular association between human papilloma virus (HPV) and cell cycle-related (CCR) proteins is not fully understood in oropharyngeal squamous cell carcinoma (OPSCC). Herein, we examined the expression levels of CCRs in OPSCCs based on HPV status. In situ hybridization (ISH)- and polymerase chain reaction (PCR)-based assays were used to detect HPV status in 98 OPSCCs, and CCRs were detected by immunostaining. Of 98 tumors, 47 had HPV-positive tumors by either ISH- or PCR-based assays. Concordance analysis between ISH- and PCR-based tests showed a good agreement in OPSCC. Expression of p16 was moderate, consistent with HPV positivity as determined by ISH-based analysis. High p53-, phospho (p)-Rb-, SKP2-, cyclin D1-, and p-c-myc-positive rates were correlated with HPV-negative tumors, whereas high p16- and p27-positive rates were associated with HPV-positive tumors. The positive rates for p21 and cyclin A did not differ between HPV-positive and HPV-negative tumors. Finally, Ki-67 positivity was commonly observed for both types of OPSCCs. Although expression of p16 is thought to be a marker of HPV infection, ISH- or PCR-based tests should be used for HPV detection. In addition, our results regarding CCRs may be helpful for understanding the carcinogenesis of OPSCC.

Epigenetic silencing of cell cycle regulatory genes during 3-methylcholanthrene and diethylnitrosamine-induced multistep rat lung cancer

The rat lung cancers induced by 3-methylcholanthrene (MCA) and diethylnitrosamine (DEN) are considered to be a good model for illustrating genetic alterations in human lung precancerous and cancerous lesions. Recently, we had reported that the model can also be used to investigate the step-by-step dynamic changes in DNA methylation during lung carcinogenesis. In this study, we have used the same animal model to further study the evolution of methylation alterations of cell cycle regulatory genes CDKN1B (p27) and CDKN1C (p57). Our results showed epigenetic alterations in p27 and p57. Promoter hypermethylation of p27 was detected in one sample of carcinoma in situ (CIS) and two samples of infiltrating carcinoma, all three of which lacked expression of the p27 protein. Methylation of the p57 promoter correlated with the loss of protein expression in lung pathologic lesions, with a gradual increase in methylation frequency from 0 sample in the normal epithelium and hyperplasia, to 11.1% in squamous metaplasia, 18.9% in dysplasia, 26.7% in CIS, and finally 36.0% in infiltrating carcinoma samples. Immunohistochemical analysis showed that p27 and p57 protein expression decreased as lung carcinogenesis progressed. Moreover, weak expression of p27 and p57 in methylated primary tumor cell lines increased markedly after treatment with 5-aza-2'-deoxycytidine (5-aza-dC), confirming that methylation was indeed responsible for the gene downregulation. These results suggest that the progression of rat lung carcinogenesis induced by MCA/DEN is associated with dynamic changes in promoter hypermethylation of cell cycle regulatory genes, including p27 and p57, accounting for their defective expression.

Histologic-type specific role of cell cycle regulators in non-small cell lung carcinoma

BACKGROUND

Lung cancer is the most lethal type of cancer in humans. Cell cycle alterations have commonly been encountered in lung cancer and may have prognostic value.

MATERIALS AND METHODS

This study investigates the immunohistochemical expression of the important cell cycle regulators phosphatase and tensin homolog deleted on chromosome 10 (PTEN), p27, Cks1, and Skp2 in 128 non-small cell lung carcinomas (64 adenocarcinomas, 46 squamous cell carcinomas, and 18 large cell undifferentiated carcinomas) and adjacent non-neoplastic lung tissue.

RESULTS

PTEN and p27 were always highly expressed in non-neoplastic lung whereas Cks1 and Skp2 were not expressed in normal tissue. Decreased PTEN expression was noted in 19/64 adenocarcinomas, 15/46 squamous cell carcinomas, and 7/18 undifferentiated large cell carcinomas. Reduced expression of p27 was noted in 28/64, 19/46, and 6/18 of the tumors, respectively. Increased expression of Cks1 was seen in 38/64, 26/46, and 11/18 and increased expression of Skp2 in 29/64, 30/46, and 14/18 of the tumors, respectively. An inverse relationship between p27 and Skp2 levels was found in adenocarcinomas and between p27 and Cks1 levels in squamous cell carcinomas. Decreased PTEN and p27 expression were associated with advanced tumor stage in squamous cell carcinomas. Univariate analysis showed that high p27 and PTEN and low Cks1 expression correlated with increased survival in patients with squamous cell carcinoma independently of tumor stage.

CONCLUSIONS

Aberrant expression of PTEN, p27, Cks1, and Skp2 is a common feature of all three major types of non-small cell lung cancer NSCLC, but seems to be involved in the progression of squamous cell carcinoma alone.

Downregulation of the KIP family members p27(KIP1) and p57(KIP2) by SKP2 and the role of methylation in p57(KIP2) inactivation in nonsmall cell lung cancer

Knowing the status of molecules involved in cell cycle control in cancer is vital for therapeutic approaches aiming at their restoration. The p27(KIP1) and p57(KIP2) cyclin-dependent kinase inhibitors are nodal factors controlling normal cell cycle. Their expression in normal lung raises the question whether they have a mutual exclusive or redundant role in nonsmall cell lung cancer (NSCLC). A comparative comprehensive analysis was performed in a series of 70 NSCLCs. The majority of cases showed significantly reduced expression of both members compared to normal counterparts. Low KIP protein levels correlated with increased proliferation, which seems to be histological subtype preponderant. At mechanistic level, degradation by SKP2 was demonstrated, in vivo and in vitro, by siRNA-methodology, to be the most important downregulating mechanism of both KIPs in NSCLC. Decreased p57(KIP) (2)-transcription complements the above procedure in lowering p57(KIP2)-protein levels. Methylation was the main cause of decreased p57(KIP) (2)-mRNA levels. Allelic loss and imprinting from LIT1 mRNA contribute also to decreased p57(KIP2) transcription. In vitro recapitulation of the in vivo findings, in A549 lung cells (INK4A-B((-/-))), suggested that inhibition of the SKP2-degradation mechanism restores p27(KIP1) and p57(KIP2) expression. Double siRNA treatments demonstrated that each KIP is independently capable of restraining cell growth. An additional demethylation step is required for complete reconstitution of p57(KIP2) expression in NSCLC.

Cytogenetic aspects of adult primary myelodysplastic syndromes: Clinical implications

Myelodysplastic syndrome (MDS) is a heterogeneous disease from the clinical, biological and morphological point of view. The pathogenesis of MDS is not well established and it appears to occur complex changes in the stem cell biology. Clonal chromosomal aberrations are found in 30-50% of primary MDS and no specific cytogenetic abnormality has as yet been defined. The chromosomal abnormalities are predominantly characterized by partial/total chromosomal losses or chromosomal gains. These chromosomal abnormalities include mainly -5/del(5q), -7/del(7q), del(11q), del(12p), del(20q), -Y, and +8. The role of cytogenetic analysis in the diagnosis, prognosis, taking treatment decisions and follow up of patients with MDS has been clearly defined. Despite its difficulties in obtaining for analysis high quality metaphases conventional cytogenetics continues to be the basic technique for cytogenetic evaluation of a MDS patient. Other molecular cytogenetic methods have been shown to be complementary, without replacing the information obtained with this technique. Further investigations with both conventional and molecular cytogenetics in relation to clinical features as well as other molecular methods will undoubtedly contribute to improve understanding of the underlying genetic events responsible for the development and evolution of MDS leading to more accurate classification and management of MDS patients.

Gene amplification and protein expression of EGFR and HER2 by chromogenic in situ hybridisation and immunohistochemistry in atypical adenomatous hyperplasia and adenocarcinoma of the lung

AIMS

To investigate the importance of gene amplification and EGFR (epidermal growth factor receptor) and HER2 protein expression during the progression of adenocarcinoma of the lung.

METHODS

EGFR and HER2 gene amplification was examined in atypical adenomatous hyperplasia (AAH), bronchioloalveolar carcinoma (BAC), and adenocarcinoma with mixed subtypes (MX) by chromogenic in situ hybridisation (CISH), and protein expression was examined by immunohistochemistry using paraffin wax embedded tissues.

RESULTS

EGFR and HER2 gene amplification was found in four and two of 86 cases, respectively, and was detected only in the invasive components of MX. EGFR and HER2 protein expression was seen in 24 and 18 of 86 cases, respectively. EGFR and HER2 proteins were not expressed in AAH but were expressed in one BAC case each. EGFR and HER2 proteins were expressed in 23 and 17 of 55 adenocarcinomas with MX. EGFR and HER2 protein expression was seen more often in the invasive components than in the BAC components of MX, and increased significantly as lesions progressed from AAH to BAC, early MX, and overt MX. Because EGFR and HER2 protein expression was frequently seen without gene amplification, other mechanisms apart from gene amplification may be associated with protein expression.

CONCLUSIONS

EGFR and HER2 gene amplification may be a late event and EGFR and HER2 protein expression may be associated with the development of adenocarcinoma of the lung.

Inhibition of mammalian target of rapamycin reverses alveolar epithelial neoplasia induced by oncogenic K-ras

The serine/threonine kinase AKT and its downstream mediator mammalian target of rapamycin (mTOR) are activated in lung adenocarcinoma, and clinical trials are under way to test whether inhibition of mTOR is useful in treating lung cancer. Here, we report that mTOR inhibition blocked malignant progression in K-ras(LA1) mice, which undergo somatic activation of the K-ras oncogene and display morphologic changes in alveolar epithelial cells that recapitulate those of precursors of human lung adenocarcinoma. Levels of phospho-S6(Ser236/235), a downstream mediator of mTOR, increased with malignant progression (normal alveolar epithelial cells to adenocarcinoma) in K-ras(LA1) mice and in patients with lung adenocarcinoma. Atypical alveolar hyperplasia, an early neoplastic change, was prominently associated with macrophages and expressed high levels of phospho-S6(Ser236/235). mTOR inhibition in K-ras(LA1) mice by treatment with the rapamycin analogue CCI-779 reduced the size and number of early epithelial neoplastic lesions (atypical alveolar hyperplasia and adenomas) and induced apoptosis of intraepithelial macrophages. LKR-13, a lung adenocarcinoma cell line derived from K-ras(LA1) mice, was resistant to treatment with CCI-779 in vitro. However, LKR-13 cells grown as syngeneic tumors recruited macrophages, and those tumors regressed in response to treatment with CCI-779. Lastly, conditioned medium from primary cultures of alveolar macrophages stimulated the proliferation of LKR-13 cells. These findings provide evidence that the expansion of lung adenocarcinoma precursors induced by oncogenic K-ras requires mTOR-dependent signaling and that host factors derived from macrophages play a critical role in adenocarcinoma progression.

Diversity in expression and prognostic significance of G1/S cyclins in human primary lung carcinomas

Expression of cyclin A, cyclin E and cdk2 was examined immunohistochemically in 144 cases of primary non-small cell lung carcinoma to evaluate their prognostic value. Cyclin A was co-expressed with cdk2 in the proliferating cells, ie those showing positive Ki-67 staining. The labelling index (LI) of cyclin A revealed a positive correlation with the S-phase fraction and an inverse correlation with histological differentiation. Furthermore, high cyclin A LIs indicated a poor prognosis in all histological types. Cyclin E exhibited a characteristic staining pattern: in squamous cell carcinoma (SCC), differentiated cells without Ki-67 staining revealed cyclin E positivity with expression of cdk2. Conversely, in adenocarcinoma (AC), proliferating cells revealed cyclin E positivity. Cases of large cell carcinoma showed heterogeneous cyclin E staining patterns, unlike those of SCC or AC. Statistical analyses also revealed a marked contrast between SCC and AC. In AC, the LI of cyclin E was inversely correlated with histological differentiation and a high LI predicted a worse prognosis. In contrast, in SCC, the LI of cyclin E correlated positively with histological differentiation and better prognosis. However, the expression levels of cyclin E mRNA evaluated by quantitative RT-PCR were higher in poorly differentiated SCC and AC, suggesting that protein turnover plays a large role in determining cyclin E protein levels. Although the expression of cyclins was demonstrated to be diversely regulated depending on the histological type, the combined immunohistochemical analyses performed in this study on these proteins could be useful tools for evaluating patient prognosis in lung carcinomas.

Colliding primary lung cancers of adenosquamous carcinoma and large cell neuroendocrine carcinoma

We report an extremely rare case of primary lung cancer showing various histological elements diagnosed as the collision of an adenosquamous carcinoma and a large cell neuroendocrine carcinoma by loss of heterozygosity (LOH) analysis of the human androgen receptor (AR) and phosphoglycerate kinase (PGK-1) genes. The tumor exhibited a tiny ground-glass opaque shadow suggesting atypical adenomatous hyperplasia 18 months prior to surgery. However, the tumor grew rapidly, and the resected tumor consisted of two closely located nodules. The larger nodule was composed of well-differentiated adenocarcinomatous and moderately to poorly differentiated squamous cell carcinomatous elements, while the smaller nodule consisted of a large cell neuroendocrine carcinomatous element with partial squamoid differentiation having focal continuity with the adenocarcinomatous element. Both the adenocarcinomatous and squamous cell carcinomatous elements revealed transitional features and LOH of AR and PGK-1 genes, while the large cell neuroendocrine carcinomatous element showed a monoclonal pattern but possessed both alleles of AR and PGK-1 genes. From these clinical and pathological results, the parental cell of the large cell neuroendocrine carcinomatous element was considered to be different from that of the adenosquamous carcinomatous element.

Mechanisms underlying nonsteroidal anti-inflammatory drug-induced p27(Kip1) expression

We demonstrated previously that nonsteroidal anti-inflammatory drugs (NSAIDs) increased p27(Kip1) by inhibiting protein degradation to suppress the proliferation of human lung cancer cells. In this study, we elucidate the molecular mechanism by which NSAIDs modulate p27(Kip1) proteolysis. Immunoblotting and in vitro ubiquitination assays indicated that the expression of Cul1 and Skp2 and ubiquitination activity toward p27(Kip1) were not regulated by NSAIDs. On the contrary, we found that NSAIDs inhibited proteasome activity to increase p27(Kip1) protein levels. NSAIDs suppressed the expression of chymotrypsin-like catalytic subunits (beta5, LMP7, and LMP2), but did not directly block enzymatic activity, to inhibit proteasome activity. Reverse transcriptase-competitive polymerase chain reaction and promoter activity assays showed that this inhibition occurred at the transcriptional level. In vitro degradation experiments showed that p27(Kip1) degradation was inhibited by NS398, and the addition of purified 26S proteasome reversed this inhibitory effect. Collectively, our results revealed the mechanism by which NSAIDs modulate p27(Kip1) protein degradation and suggest that NSAIDs are a novel class of proteasome inhibitors.

Down-regulation of p27 is associated with malignant transformation and aggressive phenotype of cervical neoplasms

OBJECTIVES

p27Kip1 (p27) is a member of the cyclin-dependent kinase inhibitor family. The level of p27 protein expression decreases during tumor development and progression in some epithelial tumors. To identify the potential implications of the p27 gene in the development of cervical carcinoma and explore the clinical importance of change in gene expression, we assessed the level of p27 protein in precancerous lesions and carcinomas of the cervix.

METHODS

In our study, 20 low-grade squamous intraepithelial lesions (LSIL), 35 high-grade squamous intraepithelial lesions (HSIL), 12 microinvasive carcinomas, and 103 invasive carcinomas were evaluated. The expression of p27 was studied by immunohistochemistry using a monoclonal antibody specific for the protein.

RESULTS

p27 was expressed in all samples of normal epithelium, LSIL, and HSIL, and the mean values of expression were 55.1, 52.8, and 45.4%, respectively. Conversely, the expression of p27 was significantly reduced in microinvasive (15.9%) and invasive carcinomas (11.2%). Furthermore, loss of p27 expression was significantly associated with lymph node metastasis (P = 0.009). However, p27 down-regulation had no influence on overall survival using univariate analysis.

CONCLUSIONS

The trend of reduced p27 expression in microinvasive and invasive carcinomas suggests that down-regulation of p27 expression is strongly linked to neoplastic transformation of cervical epithelium, and inactivation of p27 may be an early event in cervical carcinogenesis. Moreover, loss of p27 expression was related to lymph node metastasis in cervical carcinoma. These results imply that inactivation of p27 is associated with highly aggressive phenotype of cervical carcinoma.

Comparative assessment expression of the inhibitor of growth 1 gene (ING1) in normal and neoplastic tissues

Studies have indicated that the tumor suppressor p33(ING1b) (13q33-34) interact with p53. Moreover, the association of functional protein forms of each member of the p33(ING1b)/p53 complex is essential for optimum activity of p53. The present report describes the sequencing of cDNAs corresponding to the p33(ING1b) mRNAs in a series of normal and tumor cell lines, and the production of monoclonal antibodies (MAbs) reactive with p33(ING1b). These antibodies were subsequently used to analyze p33(ING1b) expression in normal and tumor cell lines and tissues. No evidence of mutation of p33(ING1b) was found in any of the 15 tumor cell lines cDNAs studied. Our investigation of a wide range of normal tissues have shown that expression of the nuclear epitope is highly ubiquitous, whereas expression of the cytoplasmic form could be detected in only 50% of tissues studied. Considering neoplastic tissues, loss of nuclear p33(ING1b) was observed in melanoma, seminoma, papillary thyroid carcinoma, ductal breast carcinoma, and acute lymphoblastic leukemia. As with normal tissue, cytoplasmic p33(ING1b) was more restricted, being observed in around 30% of neoplastic tissues, but in melanoma, papillary thyroid carcinoma, ductal breast carcinoma, there was increased detection of cytoplasmic p33(ING1b) associated with concomitant loss of nuclear expression. These results may suggest that at least in some tumors, loss of effective p33(ING1b) function may be achieved by translocation to the cytoplasm or failure of nuclear localization.

Myelodysplastic syndrome: review of the cytogenetic and molecular data

Myelodysplastic syndrome (MDS) is a monoclonal disorder of the pluripotent stem cell that frequently evolves into acute leukemia. MDS is characterized by trilineage dysplasia and by ineffective hematopoiesis. The etiology of MDS is poorly understood. However, the frequent association of chromosomal abnormalities (deletions, inversions, translocations, trisomies and monosomies) with MDS suggests that an oncogene, or a tumor suppressor gene might be involved in the pathogenesis and evolution of this disorder. This review summarizes the clinical, laboratory, chromosomal and prognostic findings of some of the cytogenetic abnormalities such as; 20q deletion, chromosome 5, 7 and 3 abnormalities, 17p-syndrome, trisomy 8, and loss of Y chromosome. In addition, this review goes into the discussion of the most recent development in the field of molecular biology to understand some of the mechanisms resulting in the development and progression of MDS.

High cyclin E and low p27/Kip1 expressions are potentially poor prognostic factors in lung adenocarcinoma patients

Cyclin E is an important regulator of entry into the S phase of the cell cycle. p27/Kip1 (p27) binds to cyclin E/Cdk2 complex and negatively regulates cell proliferation. We immunohistochemically examined the expression of cyclin E and p27 in 98 cases of resected lung adenocarcinoma to evaluate the prognostic significance of cyclin E and p27. Cyclin E was expressed in 16 cases (16%), and p27 was expressed in 41 cases (42%). Using Kaplan-Meier survival analysis, patients with cyclin E positive (P=0.0017) and p27 negative (P=0.011), both individually and in combination (P<0.0001), had a worse prognosis. We also analyzed the relationship of these findings to clinicopathological parameters, which revealed that cyclin E-positive, p27-negative cases had a higher Ki67 expression (P=0.012) and a higher rate of lymph node metastasis (P=0.0078) than other groups. Our results suggested that cyclin E over expression, in association with p27 reduction in particular, may potentially be a poor prognostic factor in lung adenocarcinoma patients. However, to verify the prognostic significance of these factors, a multivariate analysis of a larger number of patients should be undertaken.

Expression of cyclin-dependent kinase inhibitors in taste buds of mouse and hamster

Taste buds are specialized epithelial cell clusters in the oral squamous cell epithelium. Although taste buds have been reported to renew rapidly, the mechanism of cell cycle control in these specialized structures remains unresolved. To clarify the cell cycle status and role of cyclin-dependent kinase inhibitors (CDKI) for cell cycle control in the taste buds, we analyzed cell proliferation activity using bromodeoxyuridine (BrdU) and Ki-67 immunostainings and the expression of the Cip/Kip family of CDKI (p21Cip1, p27Kip1, and p57Kip2) in the circumvallate papillae of mouse and hamster. BrdU-positive cells were detected in the basal layer of the oral epithelium. In the taste buds, Ki-67-positive cells were seen in the basal area, with only a very few positive cells in the taste buds. Both p21Cip1 and p27Kip1 positive cells were seen in the suprabasal layer of the non-gustatory oral epithelium. In the taste buds, stronger p27Kip1 staining was detected than in the non-gustatory epithelium. Western blotting analysis revealed that p27Kip1 was abundant in the mucosal tissues from circumvallate papillae. Thus, our study suggests that the taste bud cells except for basal cells are post-mitotic cells and that the cell cycle arrest associated with taste bud cell differentiation could be regulated predominantly by p27Kip1.

Early glandular neoplasia of the lung

Although bronchogenic carcinomas progress through a very well defined sequence of metaplasia, dysplasia and carcinoma in situ, very little is known about the early progression of glandular neoplasms of the lung. In particular, the early precursor lesion from which fully malignant adenocarcinomas arise has effectively eluded recognition, at least until recently. Several lines of evidence now implicate atypical adenomatous hyperplasia (AAH) as an initial morphologic stage in multistep lung tumorigenesis. Despite its small size, AAH can be appreciated at the light microscopic level and characterized at the molecular genetic level. Indeed, the genetic characterization of AAH promises to further our understanding of lung cancer development and might facilitate the design of novel strategies for early detection of lung cancer.