Reduced expression of cell-cycle regulator p27(Kip1) correlates with a shortened survival in non-small cell lung cancer

Skp2: A critical molecule for ubiquitination and its role in cancer

The ubiquitin-proteasome system (UPS) is a multi-step process that serves as the primary pathway for protein degradation within cells. UPS activity also plays a crucial role in regulating various life processes, including the cell cycle, signal transduction, DNA repair, and others. The F-box protein Skp2, a crucial member of the UPS, plays a central role in the development of various diseases. Skp2 controls cancer cell growth and drug resistance by ubiquitinating modifications to a variety of proteins. This review emphasizes the multifaceted role of Skp2 in a wide range of cancers and the mechanisms involved, highlighting the potential of Skp2 as a therapeutic target in cancer. Additionally, we describe the impactful influence exerted by Skp2 in various other diseases beyond cancer.

UBAC2 promotes bladder cancer proliferation through BCRC-3/miRNA-182-5p/p27 axis

Emerging evidences have demonstrated that ubiquitin-associated domain-containing protein 2 (UBAC2) is closely related to the occurrence and development of malignant tumors. However, the functions and underlying molecular mechanisms of UBAC2 in bladder cancer (BC) development have not been defined. In this study, we found that both UBAC2 mRNA and protein levels were upregulated in BC tissues and cell lines, and knockdown of UBAC2 inhibited BC cells proliferation both in vitro and in vivo. Meanwhile, Kaplan-Meier survival plots of 406 BC cases from TCGA database showed that higher expression of UBAC2 in BC patients was associated with lower survival rate. Mechanistic studies revealed that knockdown of UBAC2 increased the expression of p27 by posttranscriptional regulation. Our previous study indicated that circular RNA BCRC-3 (BCRC-3) promoted the expression of p27 through interacting with miR-182-5p, and reversed miR-182-5p-induced inhibition of p27 3'UTR activity. In the present study, we found that UBAC2 could bind to BCRC-3, and subsequently affected the interaction of BCRC-3 with miR-182-5p to inhibit the expression of p27. Furthermore, knockdown of BCRC-3 partly reversed the upregulation of p27 expression induced by knockdown of UBAC2. Our findings highlight a novel mechanism of UBAC2 in regulating p27 through affecting the function of BCRC-3, and provide a research basis for the diagnostic and therapeutic application of BC.

Clinicopathological and Prognostic Significance of p27 Expression in Oral Squamous Cell Carcinoma: A Meta-Analysis

Despite being already known that p27 can regulate cell proliferation, cell motility and apoptosis, the role of p27 expression in oral squamous cell carcinoma (OSCC) remains controversial. The purpose of this study was to comprehensively evaluate, with a meta-analysis, the clinicopathological and prognostic role of p27 expression in OSCC. A meta-analysis of eligible studies was performed to assess the effects of p27 expression on clinicopathological parameters and overall survival (OS) in patients with OSCC, using pooled relative risks with 95% confidence intervals. Heterogeneity and publication bias were also assessed. Fourteen studies involving a total of 1,010 patients met the inclusion criteria. Low p27 expression was significantly associated with advanced TNM stage (p<0.001), worse histology (p=0.025), and lymph node metastasis (p<0.001), but not with tumor size (p=0.181). The pooled RR of 0.743 (p=0.002) suggested that low p27 expression has a poor prognosis in patients with OSCC. A significant heterogeneity among studies was detected for lymph node status (χ2=34.60, I2=68.2%, p<0.001) and OS (χ2=14.86, I2=39.4%, p=0.095). We did not detect a significant publication bias in this meta-analysis. Our meta-analysis suggests that p27 expression status might be useful as a predictive biomarker in clinical practice, and might potently predict OS in OSCC patients.

Endothelin-1 is a Novel Prognostic Factor in Non-Small Cell Lung Cancer

Endothelin-1 (ET-1) is a potent vasoactive peptide and a hypoxia-inducible angiogenic growth factor associated with the development and growth of solid tumours. This study evaluated the expression of big endothelin-1 (big ET-1), a stable precursor of ET-1, and ET-1 in non-small cell lung cancer (NSCLC). Big ET-1 expression was evaluated in paraffin-embedded tissue sections from 10 NSCLC tumours using immunohistochemistry and in situ hybridisation. The production of big ET-1 and ET-1 was studied in six established NSCLC cell lines. The plasma concentrations of big ET-1 were measured in 30 patients with proven NSCLC prior to chemotherapy by means of a sandwich enzyme-linked immunoassay and compared to levels in 20 normal controls. Big ET-1 immunostaining was detected in the cancer cells of all tumours studied. Using in situ hybridisation, tumour cell big ET-1 mRNA expression was demonstrated in all samples. All six NSCLC cell lines expressed ET-1, with big ET-1 being detected in three. The median big ET-1 plasma level in patients with NSCLC was 5.4 pg/mL (range 0–22.7 pg/mL) and was significantly elevated compared to median big ET-1 plasma levels in controls, 2.1 pg/mL (1.2–13.4 pg/mL) (p=0.0001). Furthermore, patients with plasma big ET-1 levels above the normal range (upper tertile) had a worse outcome (p=0.01). In conclusion, big ET-1/ET-1 is expressed by resected NSCLC specimens and tumour cell lines. Plasma big ET-1 levels are elevated in NSCLC patients compared to controls with levels >7.8 pg/mL being associated with a worse outcome. The development of selective ET-1 antagonists such as Atrasentan indicates that ET-1 may be a therapeutic target in NSCLC.

Association of cytoplasmic p27 expression with an unfavorable response to cisplatin-based chemotherapy and poor outcomes in non-small cell lung cancer

Reduced nuclear p27 expression is associated with a poor outcome in various cancers, including non-small cell lung cancer (NSCLC). Cytoplasmic p27 expression was shown to be associated with an unfavorable response to chemotherapy and poor outcomes in some carcinomas, but it has not been well studied in NSCLC. Herein, p27 expression in 219 tumors surgically resected from NSCLC patients was evaluated by immunohistochemistry (IHC). The most common of p27 immunostaining in lung tumors was observed in the cytoplasm (N-/C+, 32 %), followed by negative (N-/C-, 29 %), nucleus (N+/C-, 24 %), and nucleus plus cytoplasm (N+/C+, 15 %). Kaplan-Meier and Cox regression models showed that p27 N-/C+ tumors exhibited the worst overall survival (OS) and relapse-free survival (RFS) among the four categories of tumors. Among 135 of 219 patients who received cisplatin-based chemotherapy, p27 N-/C+ tumors most commonly showed an unfavorable response to cisplatin-based chemotherapy, followed by p27 N-/C- tumors when p27 N+/C- tumors were used as a reference. IHC analysis for phosphorylated extracellular signal-regulated kinase (p-ERK) and Bcl-2 expression in the lung tumors was performed to test whether ERK activation could enhance p27 nuclear export and the expression of Bcl-2 to test whether ERK activation could enhance p27 nuclear export and Bcl-2 expression. The data showed that p-ERK expression was positively correlated with cytoplasmic p27 (N-/C+) and Bcl-2 expression in the lung tumors. Patients with high Bcl-2-expressing tumors treated with cisplatin-based chemotherapy showed unfavorable predictive values in a subset of this study population. Therefore, we suggest that cytoplasmic p27 (N-/C+) via ERK-activated Bcl-2 expression may predict an unfavorable response to cisplatin-based chemotherapy and poor outcomes in NSCLC.

A novel differential diagnostic model for multiple primary lung cancer: Differentially-expressed gene analysis of multiple primary lung cancer and intrapulmonary metastasis

The incidence of synchronous multiple primary lung cancer (MPLC) is increasing. However, present diagnostic methods are unable to satisfy the individualized treatment requirements of patients with MPLC. The present study aimed to establish a quantitative mathematical model and analyze its diagnostic value for distinguishing between MPLC and cases of the histologically similar disease, intrapulmonary metastasis (IPM). The sum value of the differential expression ratios of four proteins, namely p53, p16, p27 and c-erbB2, was evaluated by immunohistochemically-staining specimens of primary cancers, second separate cancers, metastatic lymph nodes and metastatic cancers. The sum value of the differential expression ratio of the four proteins from the primary tumor and the lymph-node metastasis or metastatic cancer was <90 in the 11 patients with a single metastatic cancer and in the 30 patients with lymph-node metastasis, but was >90 in the 14 patients with different histological types of MPLC. Therefore, a quantitative differentially-expressed gene mathematical model was established as follows: Sum of the differential expression ratios = p16T1 - T + p27T1 - T2 + C-erbB2T1 - T2 + p53T1 - T2, where T1 is the primary cancer and T2 is the lymph node metastasis, metastatic cancer or the second separate cancer. The quantitative differentially-expressed gene mathematical model is considered to be a useful tool for distinguishing between MPLC and IPM.

SIRT1 inactivation evokes antitumor activities in NSCLC through the tumor suppressor p27

P27(Kip1) (CDKN1B) regulates cellular proliferation and senescence, and p27(Kip1) deficiency in cancer is strongly correlated with poor prognosis of multiple cancer types. Understanding the mechanism of p27(Kip1) loss in cancer and the consequences of restoring p27(Kip1) levels is therefore critical for effective management during therapy. Here, SIRT1, a class III histone deacetylase (HDAC), is identified as an important regulator of p27(Kip1) expression. Mechanistically, SIRT1 reduces p27(Kip1) expression by decreasing p27(Kip1) protein stability through the ubiquitin-proteasome pathway. In addition, SIRT1 silencing suppresses non-small cell lung cancer (NSCLC) proliferation and induces senescence in a p27(Kip1)-dependent manner. Furthermore, SIRT1 silencing dramatically suppresses tumor formation and proliferation in two distinct NSCLC xenograft mouse models. Collectively, these data demonstrate that not only SIRT1 is an important regulator of p27(Kip1) but also SIRT inhibition induces senescence and antigrowth potential in lung cancer in vivo.

IMPLICATIONS

SIRT1 is a key regulator of p27 protein levels and SIRT1 inhibition is a viable strategy for NSCLC therapy by means of p27 reactivation.

Dual effects of Ral-activated pathways on p27 localization and TGF-β signaling

Constitutive activation or overactivation of Ras signaling pathways contributes to epithelial tumorigenesis in several ways, one of which is cytoplasmic mislocalization of the cyclin-dependent kinase inhibitor p27(Kip1) (p27). We previously showed that such an effect can be mediated by activation of the Ral-GEF pathway by oncogenic N-Ras. However, the mechanism(s) leading to p27 cytoplasmic accumulation downstream of activated Ral remained unknown. Here, we report a dual regulation of p27 cellular localization by Ral downstream pathways, based on opposing effects via the Ral effectors RalBP1 and phospholipase D1 (PLD1). Because RalA and RalB are equally effective in mislocalizing both murine and human p27, we focus on RalA and murine p27, which lacks the Thr-157 phosphorylation site of human p27. In experiments based on specific RalA and p27 mutants, complemented with short hairpin RNA-mediated knockdown of Ral downstream signaling components, we show that activation of RalBP1 induces cytoplasmic accumulation of p27 and that this event requires p27 Ser-10 phosphorylation by protein kinase B/Akt. Of note, activation of PLD1 counteracts this effect in a Ser-10-independent manner. The physiological relevance of the modulation of p27 localization by Ral is demonstrated by the ability of Ral-mediated activation of the RalBP1 pathway to abrogate transforming growth factor-β-mediated growth arrest in epithelial cells.

2-Amino-1,3,4-thiadiazole derivative (FABT) inhibits the extracellular signal-regulated kinase pathway and induces cell cycle arrest in human non-small lung carcinoma cells

The anticancer potential of 2-amino-1,3,4-thiadiazole compounds has been documented by in vitro and in vivo studies. In our previous research, we described the synthesis as well as the antiproliferative and neuroprotective activities of 2-(4-fluorophenyloamino)-5-(2,4-dihydroxyphenyl)-1,3,4-thiadiazole (FABT). The aim of the present study was to investigate the molecular mechanisms involved in FABT-induced growth inhibition in A549 lung carcinoma cells. Western blotting analysis revealed that FABT inhibited the activation of the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway, and Real-time PCR analysis showed no changes in the expression of P44ERK1 and CREB1 genes. Furthermore, FABT induced cell cycle arrest in the GO/G1 phase and enhanced p27/Kip1 expression. Our results suggest that FABT acts by inhibiting ERK1/2 pathway and cell cycle progression through G1 into S phase in A549 cells. Further studies are needed to completely explain the molecular mechanisms of anticancer action of this 2-aminothiadiazole derivative.

High p27 expression is associated with a better prognosis in East Asian non-small cell lung cancer patients

BACKGROUND

The role of the anti-apoptotic protein p27 in non-small cell lung cancer (NSCLC) remains controversial. To clarify its association with survival in NSCLC, we performed a systematic review of the literature with meta-analysis.

METHODS

Trials were selected for further analysis if they provided an independent assessment of p27 in NSCLC and reported the analysis of survival data based on p27 status. A total of 11 trials, which comprised 1646 patients, provided sufficient information for the meta-analysis. Sensitivity analyses were conducted using histology, disease stage and ethnicity.

RESULTS

The combined hazard ratio (HR) of 1.50 (95% CI=1.15-1.97; P<0.001 for heterogeneity) suggested that high p27 expression has a favorable impact on survival. When the studies were restricted to those of East Asian populations, patients that expressed high levels of p27 showed a better survival rate (HR 1.73, 95% CI=1.36-2.21; P=0.169 for heterogeneity) than those that did not express high levels of p27. In addition, the heterogeneity and publication bias disappeared.

CONCLUSION

In NSCLC, high p27 expression is associated with a better prognosis among East Asians.

C10ORF97 is a novel tumor-suppressor gene of non-small-cell lung cancer and a functional variant of this gene increases the risk of non-small-cell lung cancer

In an earlier study we showed that C10ORF97 (chromosome-10, open reading frame-97) was expressed in almost all of the tissues and cell lines tested, and that it inhibited the growth of seven tumor cell lines, including two lung carcinoma cell lines (A549 and PG). Here, we show that C10ORF97 is downregulated in non-small-cell lung cancer (NSCLC) tissue compared with normal lung tissue. Overexpression of C10ORF97 significantly suppressed human lung carcinoma A549 cell growth (proliferation and anchorage-independent growth in soft agar) and motility (migration and adhesion). This tumor-suppressive function of C10ORF97 was also verified in vivo. We further found that C10ORF97 caused G(1) arrest of A549 cells and modulated the expression level of several cell-cycle regulators (such as CDK2, cyclin-E and p27). These effects of C10ORF97 were mediated by physical association between C10ORF97 and Jun-activating domain-binding protein-1 (JAB1), and blocking of JAB1-mediated translocation of p27 from the nucleus to the cytoplasm. Together, these results indicated that C10ORF97 functions as a novel tumor suppressor by modulating several key G(1)/S-regulatory proteins by interacting with JAB1. These findings led us to hypothesize that a single-nucleotide polymorphism (SNP) in the C10ORF97 gene that affects its expression might be associated with susceptibility to NSCLC. SNP216 C>T (rs2297882) in the C10ORF97 Kozak sequence was identified, and allele T of SNP216 suppressed C10ORF97 expression in vitro and in vivo. Furthermore, the TT genotype of SNP216 was associated with an increased risk of NSCLC (adjusted odds ratio=1.73 (95% confidence interval: 1.33-2.25), P=4.6 × 10(-5)). These data indicated that C10ORF97 is a tumor suppressor of NSCLC progression and C10ORF97-SNP216 may serve as a predictor of NSCLC.

p27: a barometer of signaling deregulation and potential predictor of response to targeted therapies

Phosphorylation of the cyclin-dependent kinase inhibitor p27 by upstream mitogenic signaling pathways regulates its stability, localization, and biological function. In human cancers, loss of the antiproliferative action of p27 can arise through reduced protein levels and/or cytoplasmic mislocalization, leading to increased cell proliferation and/or cell migration, respectively. Reduced p27 expression levels and p27 mislocalization have potential prognostic and therapeutic implications in various types of human cancers. This review highlights mechanisms of functional deregulation of p27 by oncogenic signaling that provide an important molecular rationale for pathway targeting in cancer treatment.

New biomarkers for lung cancer

IMPORTANCE OF THE FIELD

Despite many efforts to improve early detection, lung cancer remains the leading cause of cancer deaths. Stage is the main determinant of prognosis and the basis for deciding treatment options. Screening tests for lung cancer have not been successful so far.

AREAS COVERED IN THE REVIEW

The article reviews the available literature related to biomarkers in use at present and those that could be used for early diagnosis, staging, prognosis, response to therapy and prediction of recurrence. The single biomarkers are analysed, divided according to the technological methods used and the locations of sampling.

WHAT THE READER WILL GAIN

The reader will gain knowledge on biomarkers in use and those now under study. The reader will also gain insights into the difficulties pertaining to the development of biomarkers, results reproducibility and clinical application.

TAKE HOME MESSAGE

Although some markers seem to be promising, at present there is no consensus on the proven value of their clinical use in lung cancer. The future lies probably in a panel of biomarkers instead of individual assays, or in predictive models derived from the integration of clinical variables and gene expression profiles.

Role of cell cycle regulators in lung carcinogenesis

Cellular division is an ordered, tightly regulated process involving multiple checkpoints that assess extracellular growth signals, cell size and DNA integrity. Progression throughout the cell cycle is based on the activation of different CDK-cyclin complexes that prevent cells from entering into a new phase until thay have successfully complete the previous one. In addition, a series of cell cycle checkpoints are designed to preserve genome integrity and chromosomal stability. Neoplastic lung cells develop the ability to bypass several of these checkpoints, and tumor cell proliferation is frequently associated with genetic or epigenetic alterations in key regulators of the cell cycle. The goal of this review is to summarize the knowledge about the dysregulation of major cell cycle regulators in lung cancer pathogenesis and to discuss the use of these proteins as targets for therapeutic intervention.

p21Waf1/Cip1REGULATES PROLIFERATION AND APOPTOSIS IN AIRWAY EPITHELIAL CELLS AND ALTERNATIVE FORMS HAVE ALTERED BINDING ACTIVITIES

p21(Waf1/Cip1) plays central roles in proliferation, differentiation, and apoptosis. Alterations in the expression and subcellular localisation of p21 occur during several lung diseases but the roles of p21 in the lung epithelium are unknown. The effects of p21 on proliferation and apoptosis in mouse airway epithelial cells (AECs) were examined using p21-null mice. AECs isolated from p21-null mice had increased proliferation and apoptotic rates compared to AECs from wild-type mice. Alterations in the subcellular localization of the cell cycle regulatory proteins p27, PCNA, and p53 were also evident in p21(-/-) cells. The nuclear and cytoplasmic forms of p21 present in AECs were also examined. Full-length p21 (20 kDa) was detected in nuclear fractions but a C-terminal truncated form (17 kDa) of p21 was present in cytoplasmic fractions. The binding activities of truncated p21 were altered compared to full-length p21. Although the latter was complexed with PCNA, Cdk2, Cdk4, Cdk6, cyclin D3, and cyclin E, truncated p21 was bound only to Cdk4 and cyclin D3. In conclusion, p21 regulates proliferation and protects against apoptosis in AECs. In addition, different forms of p21 are present in AECs and the subcellular localization of these forms reflects differences in p21 activity.

CHFR expression is preferentially impaired in smoking-related squamous cell carcinoma of the lung, and the diminished expression significantly harms outcomes

Loss of tumor suppressors and activation of oncogenes lead to carcinogenesis. Abnormal expression of CHFR, a novel checkpoint gene, or of Aurora kinases, key regulators of mitosis, has been detected in a variety of solid tumors. Recently, CHFR has been revealed to ensure chromosomal stability by controlling the expression level of Aurora-A in vitro. However, the frequency of aberrant expression of these proteins and the association with clinicopathologic parameters remain poorly defined in nonsmall-cell lung cancer (NSCLC). In this study, we investigated the immunohistochemical protein expression of CHFR and Aurora-A in 157 NSCLC cases and evaluated the association between clinicopathologic parameters statistically. The relationship between CHFR protein and mRNA levels and the association between this relationship and promoter methylation of the CHFR gene were also examined in 20 frozen sections of NSCLC. Overexpression of Aurora-A and reduced expression of CHFR were found in 94 cases (59.8%) and 62 cases (39%) of NSCLC, respectively, and those were significantly correlated with tumor differentiation and size. Moreover, diminished CHFR expression was significantly associated with smoking-related squamous cell carcinoma cases and poor prognosis. Multivariate analysis revealed that CHFR expression was an independent prognostic factor. A statistical correlation was evident between CHFR protein and mRNA expression. In conclusion, our results suggest the aberrant expression of Aurora-A and/or of CHFR contributed to the increase in the malignant potential of NSCLC. We also revealed that CHFR expression was predominantly impaired in smoking-related squamous cell carcinoma and might be a useful prognostic marker in NSCLC.

The Cdk inhibitor p27 in human cancer: prognostic potential and relevance to anticancer therapy

The cyclin-dependent kinase (Cdk) inhibitor p27 (also known as KIP1) regulates cell proliferation, cell motility and apoptosis. Interestingly, the protein can exert both positive and negative functions on these processes. Diverse post-translational modifications determine the physiological role of p27. Phosphorylation regulates p27 binding to and inhibition of cyclin-Cdk complexes, its localization and its ubiquitin-mediated proteolysis. In cancers, p27 is inactivated through impaired synthesis, accelerated degradation and by mislocalization. Moreover, studies in several tumour types indicate that p27 expression levels have both prognostic and therapeutic implications.

Analysis of molecular pathological factors of unfavorable prognosis for young cervical cancer patients

The aim of this study was to explore the molecular pathological characteristics of cervical cancer in women aged below 35, disclose the factors that indicate the unfavorable prognosis, and provide some useful targets for improving therapeutic outcome.

PATIENTS AND METHODS

64 cases of pathological data originating from cervical cancer patients aged below 35 served as the study group to perform a retrospective research, and pathological data from 90 cases of cervical cancer patients beyond age 35, who underwent treatment during the same time, were selected at random as the reference group. Immunohistochemistry and quantified image analysis were utilized to detect synchronously the protein expression difference of survivin and p27 between the 2 groups.

RESULTS

The total 5-year survival rate of the study group was 65.6% compared to 84.4% in the reference group, while the lymph node metastasis rate was 25% compared to 12.2% in the reference group. Both differences were statistically significant (p < 0.05). Survivin expression is much greater in the study group than in the reference group (p < 0.05); there is no statistical difference of the p27 expression between the 2 groups (p > 0.05), but p27 expression is related to lymph node metastasis.

CONCLUSION

Younger female patients have a worse prognosis than older ones, and survivin expression is associated with poor prognosis. Targeting these molecular factors may lead to a hopeful biomedical therapy to improve the prognosis of young female cervical cancer patients.

Reduced XPC messenger RNA level may predict a poor outcome of patients with nonsmall cell lung cancer

BACKGROUND

Homologous deletion of the xeroderma pigmentosum complementary group C (XPC) repair gene frequently causes lung adenocarcinoma in mice, suggesting that an XPC defect may play a critical role in lung tumorigenesis. The current study attempted to determine whether reduced XPC mRNA levels predict the clinical outcome of lung cancer patients.

METHODS

XPC, p27(kip) (cdk inhibitory protein), and S-phase kinase-associated protein (skp2) levels were evaluated by Western blot analysis in a series of lung cancer cell lines with different invasive abilities. Migration and invasive abilities were measured using a modified Boyden chamber without and with Matrigel, respectively. To test whether XPC affects cell invasive ability, XPC gene protein expression was reduced in low invasive cells by RNA interference (RNAi) and assayed with Boyden chamber. XPC mRNA levels in 126 nonsmall cell lung cancers (NSCLCs) were examined by real-time-reverse-transcriptase polymerase chain reaction (RT-PCR). The prognostic value of XPC mRNA expression was statistically analyzed by the Kaplan-Meier method and Cox proportional hazards regression.

RESULTS

The expression of XPC was reduced with increasing invasive potential in CL1-series lung cancer cell lines. When the XPC level was reduced by RNAi, cell migration and invasiveness increased markedly; the increased invasiveness may be caused by decreased expression of p27(kip) and increased expression of skp2 and E2F transcription factor 1. To determine whether reduced XPC expression was correlated with tumor aggressiveness and poor patient survival, XPC mRNA levels were evaluated by real-time RT-PCR. Kaplan-Meier analysis demonstrated that the median survival of patients with lower XPC mRNA levels was shorter compared with patients with higher XPC mRNA levels (P = .0440). Cox regression analysis further indicated that XPC mRNA level may act as an independent prognostic factor for NSCLC patients (P = .014).

CONCLUSIONS

The results of the current study suggest that reduced XPC mRNA level may constitute an independent prognostic factor for NSCLC patients.

Immunohistochemical markers of prognosis in non-small cell lung cancer: a review and proposal for a multiphase approach to marker evaluation

Characteristics of the tumour that affect and predict the survival outcome of patients with cancer are prognostic markers for cancer. In non-small cell lung carcinoma (NSCLC), stage is the main determinant of prognosis and the basis for deciding options for treatment. Patients with early-stage tumour are treated by complete surgical resection, which is curative in 40-70% of patients. That there are other factors important in determining the biology of these tumours, especially genes that have a role in metastasis, is indicated. Such factors could potentially be used to further classify patients into groups according to substages that may be treated differently. During the past decade, a large number of proteins that are putatively important in carcinogenesis and cancer biology have been studied for their prognostic value in NSCLC, but none of them have been proved to be sufficiently useful in clinical diagnosis. Several markers (epidermal growth factor receptor, human epidermal growth factor receptor 2, Ki-67, p53 and Bcl-2) have been studied exhaustively. Ki-67, p53 and Bcl-2 are suggested to be important but weak prognostic markers, by meta-analyses of the results. Cyclin E, vascular endothelial growth factor A, p16(INK4A), p27(kip1) and beta-catenin are promising candidates, but require further study in large randomised clinical trial samples by using standardised assays and scoring systems. Some issues and inconsistencies in the reported studies to date are highlighted and discussed. A guideline for a multi-phase approach for conducting future studies on prognostic immunohistochemistry markers is proposed here.

Overexpression of Jun activation domain-binding protein 1 in nonsmall cell lung cancer and its significance in p27 expression and clinical features

BACKGROUND

Decreased expression of p27, which is an inhibitor of cyclin-dependent kinase, is associated with cancer aggressiveness. It is believed that Jun activation domain-binding protein 1 (Jab1) plays a role in p27 degradation in a manner that is independent from the role played by S-phase kinase-associated protein 2 (Skp2). To examine the clinical significance of Jab1 in nonsmall cell lung cancer (NSCLC), the protein expression of Jab1 in tumor tissues was investigated with regard to the expression of p27 and Skp2.

METHODS

The clinicopathologic features and immunohistochemical expression levels of Jab1, p27, and Skp2 proteins were studied in 138 specimens from patients who underwent surgical resection for NSCLC. Survival analyses were performed by using the Kaplan-Meier method and Cox regression models.

RESULTS

High Jab1 expression (>50% of cancer cell nuclei stained) was observed in 81 specimens (59%). In Skp2-negative specimens (n = 81), an inverse correlation between the protein expression of p27 and Jab1 was observed both with the chi-square test (P = .02) and with the Mann-Whitney U test (P = .02). High Jab1 expression levels were related to poor outcomes in 118 patients who underwent complete resection, with a 5-year overall survival rate of 43.9% for patients who had high Jab1 expression and 63.1% for patients who had low Jab1 expression (P = .01). This difference was greater in patients who had Skp2-negative specimens (51.9% vs. 79.3% (P = .02), but it was not significant in patients who had Skp2-positive specimens. The multivariate analysis revealed that Jab1 expression was an independent prognostic factor for survival in patients with NSCLC (relative risk, 2.247; P = .01).

CONCLUSIONS

The current results showed for the first time that high Jab1 protein expression is related to poor outcome in patients with NSCLC and that this protein may be a target of therapy in NSCLC.

Prognostic implications of cell cycle, apoptosis, and angiogenesis biomarkers in non-small cell lung cancer: a review

Lung cancer is the leading cause of cancer death in the U.S. with survival restricted to a subset of those patients able to undergo surgical resection. However, even with surgery, recurrence rates range from 30% to 60%, depending on the pathologic stage. With the advent of partially effective, but potentially toxic adjuvant chemotherapy, it has become increasingly important to discover biomarkers that will identify those patients who have the highest likelihood of recurrence and who thus might benefit most from adjuvant chemotherapy. Hundreds of papers have appeared over the past several decades proposing a variety of molecular markers or proteins that may have prognostic significance in non-small cell lung cancer. This review analyzes the largest and most rigorous of these studies with the aim of compiling the most important prognostic markers in early stage non-small cell lung cancer. In this review, we focused on biomarkers primarily involved in one of three major pathways: cell cycle regulation, apoptosis, and angiogenesis. Although no single marker has yet been shown to be perfect in predicting patient outcome, a profile based on the best of these markers may prove useful in directing patient therapy. The markers with the strongest evidence as independent predictors of patient outcome include cyclin E, cyclin B1, p21, p27, p16, survivin, collagen XVIII, and vascular endothelial cell growth factor.

Validation of molecular and immunological factors with predictive importance in lung cancer

Histological classification and staging are cornerstones of diagnosis in lung cancer. Treatment options have been enriched in the last few years by the development of a number of new drugs, and therapy is now increasingly being carried out within multimodal concepts and at earlier stages. Still, outcome of the disease is far from satisfactory and progress in clinical and preclinical research is time-consuming. With the whole variety of potent new therapeutic compounds including classical cytostatics and biological factors at hand, many now believe that a clear improvement of treatment results will be derived from a better understanding of the biology of these tumours and a resulting improvement of diagnosis. Biological factors reflecting the underlying tumour biology and aspects of clinically important pathomechanisms may not only better predict outcome of the disease but also of its treatment, serving as surrogate markers for a more appropriate general intensification of therapy and ideally for specific "targeted" interventions. This article describes the different insights in the biology of these tumours in relation with the representing surrogate markers, and opens routes to possible diagnostic and therapeutic consequences.

Regulation of p27 by S-phase kinase-associated protein 2 is associated with aggressiveness in non-small-cell lung cancer

PURPOSE

The F-box protein S-phase kinase-associated protein 2 (Skp2) is one of the positive regulators of the cell cycle that promote ubiquitin-mediated proteolysis of the cyclin-dependent kinase inhibitor p27. In this study, we investigated the significance of Skp2 expression in human non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Clinicopathologic features and immunohistochemical expression of Skp2 and p27 proteins were studied in 138 patients with NSCLC. Survival analyses were performed using the Kaplan-Meier method and the Cox regression model. To analyze the role of Skp2 in vitro, NSCLC cells were transfected with an Skp2-expressing vector or small interfering RNA.

RESULTS

Skp2 was overexpressed in males, smokers, patients with squamous cell carcinomas, and patients with poorly differentiated cancers (P = .034, < .0001, < .0001, and .002, respectively). The multivariant analysis revealed that Skp2 expression is an independent prognostic factor for survival in NSCLC. An inverse relationship of Skp2 with p27 expression was observed (P = .012), and patients with both a higher expression of Skp2 and a lower expression of p27 showed a significantly unfavorable prognosis (P = .0002). In vitro ectopic expression of Skp2 in NSCLC cells reduced the protein level of p27. Conversely, induction of Skp2 siRNA increased the protein level of p27, leading to growth inhibition in NSCLC cells.

CONCLUSION

Skp2 overexpression is closely associated with the suppression of p27 and the aggressiveness in NSCLC. It also could be a therapeutic target in NSCLC.

Proteasome inhibition with PS-341 (bortezomib) in lung cancer therapy

PS-341 (bortezomib) represents a new class of therapeutics that targets the ubiquitin-proteasome pathway. It has broad-spectrum single-agent anticancer activity and can potentiate chemotherapy and radiation in preclinical models. Early phase clinical studies have shown tolerability and activity in multiple myeloma, lymphoma, prostate cancer, and lung cancers. By its mechanism of inhibiting protein degradation, PS-341 targets a wide range of pathways relevant to tumor progression and therapy resistance and can directly modulate expression of cyclins, p27(Kip1), p53, nuclear factor-kappaB, Bcl-2, and Bax. PS-341 is currently in phase I/II clinical development in both non-small cell lung cancer and small cell lung cancer. This article will review the preclinical and clinical experience with PS-341 as it relates to lung cancer.

p27/Kip1 mediates retinoic acid-induced suppression of ovarian carcinoma cell growth

We have investigated the mechanisms by which all-trans retinoic acid (ATRA) causes growth inhibition of ovarian carcinoma cells. As a model, we have studied the CAOV3 cell line, which is sensitive to ATRA, and the SKOV3 cell line, which is resistant. We have found that treatment of CAOV3 cells with ATRA causes a 5-10 fold increase in the protein level of the cyclin dependent kinase inhibitor p27/Kip1. p27/Kip1 protein upregulation is important in ovarian carcinoma as primary tumors are frequently found lacking this protein. The increase in p27/Kip1 is detected by day 3 of ATRA treatment of CAOV3 cells, and is maximal by day 5. Messenger RNA levels of p27/Kip1 do not change in CAOV3 cells following ATRA treatment, however, we have shown that p27/Kip1 mRNA is more stable in ATRA treated CAOV3 cells. Conversely, the ATRA resistant cell line SKOV3 fails to show p27/Kip1 accumulation. Interestingly, the SCF component protein SKP2 appears to be decreased in CAOV3 cells treated with ATRA. We have also shown that the ATRA dependent increase in p27/kip1 protein in CAOV3 cells leads to a decrease in the kinase activity of cyclin dependent kinase 4 (CDK4) following ATRA treatment. Finally, we found that CAOV3 cells stably transfected with a p27/kip1antisense construct, which express lower levels of p27/kip1 following ATRA treatment, and have a higher CDK4 kinase activity are less sensitive to ATRA induced growth suppression. Taken together our data suggest ATRA-induced growth inhibition in CAOV3 ovarian carcinoma cells involves modulation of the CDK inhibitor p27/kip1.

Alterations of tumor suppressor genes (Rb, p16, p27 and p53) and an increased FDG uptake in lung cancer

OBJECTIVE

The FDG uptake in lung cancer is considered to reflect the degree of malignancy, while alterations of some tumor suppressor genes are considered to be related to the malignant biological behavior of tumors. The aim of this study is to examine the relationship between FDG-PET and alterations in the tumor suppression genes of lung cancer.

METHODS

We examined 28 patients with primary lung cancer who underwent FDG-PET before surgery consisting of 17 patients with adenocarcinoma, 10 with squamous cell carcinoma and 1 with large cell carcinoma. The FDG-PET findings were evaluated based on the standardized uptake value (SUV). Alterations in the tumor suppressor genes, Rb, p16, p27 and p53, were evaluated immunohistochemically.

RESULTS

The FDG uptake in lung cancer with alteration in each tumor suppressor gene tended to be higher than in those genes without alterations, although the differences were not significant. In 15 tumors with alterations in either tumor suppressor genes, the FDG uptake was 6.83 +/- 3.21. On the other hand, the mean FDG uptake was 1.95 in 2 tumors without alterations in any genes. The difference in the FDG uptake between the 2 groups was statistically significant (p < 0.001).

CONCLUSIONS

In conclusion, the presence of abnormalities in the tumor suppressor genes, which results in an accelerated cell proliferation, is thus considered to increase the FDG uptake in lung cancer.

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.

Matrix metalloproteinase-9 in lung remodeling

Matrix metalloproteinase (MMP)-9 (Gelatinase B, 92-kD type IV collagenase, EC 3.4.24.35) is an MMP that is present in low quantities in the healthy adult lung, but much more abundant in several lung diseases, including asthma, idiopathic pulmonary fibrosis (IPF), and chronic obstructive pulmonary disease (COPD). Despite numerous reports of MMP-9 in these and other lung diseases, whether MMP-9 is causal in lung remodeling or part of the inflammatory and reparative response remains to be determined. Many intrinsic lung cells can be stimulated to produce MMP-9, but much of the information regarding MMP-9 in the lung deals with MMP-9 from inflammatory cells. The multiple locations and cell types producing MMP-9 are consistent with multiple functions in different microenvironments. In addition to digestion of structural proteins and antiproteases, MMP-9 can modify cellular function by regulation of cytokines and matrix-bound growth factors. Determining the role of MMP-9 in health and disease will be important, because broad spectrum and specific inhibitors will soon be available to enable conversion of the bench knowledge to bedside practice. This review addresses the current understanding of MMP-9 in human asthma, IPF, and COPD, and in animal models of these conditions.

Prognostic significance of p27KIP1 expression in resected non-small cell lung cancers: analysis in combination with expressions of p16INK4A, pRB, and p53

BACKGROUND AND OBJECTIVES

Whether a prognostic role for expression of the tumor suppressor gene (TSG) products exists in resected non-small call lung cancers (NSCLCs) remains controversial. Our study was performed to determine the value of TSGs expressions for patients survival in NSCLCs.

METHODS

We examined 108 resected NSCLCs for the expression of TSG products, p27(KIP1), p16(INK4A), pRB, and p53 that govern cell cycle transition by immunohistochemistry and compared them with patient clinical characteristics and prognoses.

RESULTS

Abnormal expressions of p27(KIP1), p16(INK4A), pRB, and p53 were found in 61 (57%), 53 (49%), 42 (39%), and 48 (44%), respectively, of the 108 NSCLCs. Univariate analysis showed abnormal expression of p27(KIP1) to be a strong indicator for poor patient survival, not only in the total cohort (P = 0.0024), but also in subgroups with T1-T2 (P = 0.016), N0 (P = 0.047), and squamous cell carcinomas (P = 0.026), but not according to the expression of p16(INK4A), pRB, or p53. In the Cox regression analysis, p27(KIP1) expression was found to be an independent prognostic factor (P = 0.0148) and associated with pathological stage (P = 0.0278).

CONCLUSIONS

Our results suggest that abnormal p27(KIP1) expression may be a useful indicator to predict postoperative prognosis, especially in patients with early stage NSCLCs, as compared to other TSG products examined.