Shujun Cheng

Detection of p16 hypermethylation in circulating plasma DNA of non-small cell lung cancer patients

We detected tumor-associated aberrant hypermethylation of the p16 gene in plasma DNA from 105 non-small cell lung cancer (NSCLC) patients (65 squamous cell carcinoma (SCC) and 40 adenocarcinoma (ADC)) and 92 matched tumor DNA samples, using a modified semi-nested methylation-specific PCR (MSP). This technique increased the sensibility of detecting p16 hypermethylation from DNA samples in varying stages. p16 hypermethylation was present in 73.3% (77/105) of the plasma samples, and 79.3% (73/92) of the tumor samples. Among those cases with methylated p16 sequence in tumor samples, 87.7% (64/73) also demonstrated this epigenetic alteration in the corresponding plasma DNA. Only patients whose tumor cells had hypermethylated p16 gene exhibited aberrant methylation in their plasma samples. Regarding different clinical stages of SCC and ADC, the frequencies of p16 hypermethylation in plasma DNA were nearly the same as those in corresponding tumors, except for stage I ADC. Our study indicated that aberrant methylation of p16 may be an excellent biomarker for early diagnosis and follow-up of NSCLC patients, and MSP is a reliable method for these purposes.

Prognostic significance of matrix metalloproteinase-1 levels in peripheral plasma and tumour tissues of lung cancer patients

Matrix metalloproteinase-1 (MMP-1) participates in a variety of physiological and pathological processes. We previously found that MMP-1 was one of the lung cancer-related proteins detectable in peripheral blood. To validate our preliminary observations and explore the clinical significance of MMP-1 for lung cancer further, we carried out the present study. The concentrations of MMP-1 in circulating plasma specimens of 170 lung cancer patients and 70 healthy individuals were measured by an enzyme-linked immunosorbance assay. The expression status of the MMP-1 in archival tissue samples from 122 lung cancer patients was examined by immunohistochemical analysis. The correlation between the MMP-1 levels and prognosis of the lung cancer patients was then assessed statistically. Protein levels of MMP-1 were considerably raised in the plasma from lung cancer patients relative to those in healthy controls. The high plasma MMP-1 levels were associated with advanced-stage of the disease and significantly lower overall survival rate of the patients. Coincidently, MMP-1 protein extraordinarily overexpressed in the tumour tissues of lung cancer; and the up-regulated MMP-1 was associated with the progression (including tumour size, staging and lymphatic invasion), especially with decreased survival rate of the patients. Statistic analysis revealed that MMP-1 protein levels had an independent influence on survival. MMP-1 levels were elevated in both tumour tissue and blood; the latter may serve as an independent predictor for survival of lung cancer patients. MMP-1 protein levels in plasma/serum thus represent a potential and clinically relevant biomarker for the prognosis of patients with lung cancers.

Chromosome 3 imbalances are the most frequent aberration found in non-small cell lung carcinoma.

The chromosomal imbalances in nine cases of primary non-small cell lung cancer (NSCLC) and two cell lines derived from normal human bronchial epithelial (HBE) tissue were identified by comparative genomic hybridization (CGH). Gain of material from 3q and loss of 3p material were the most frequent changes in the primary tumors. Other commonly found imbalances included gain of material from 1q, 7p, 8q, 9q, 17q and 20q, and losses involving 4, 5q, 8p, 10 and 13q. High level gain was found in two cases, both encompassing the 3q23-q27 region. Loss of 3p was also found in both of the HBE cell lines suggesting that loss of one or more tumor supressor genes on 3p may be important for epithelial transformation and could be involved in the earlier stages of lung cancer development.

DLK1 Promotes Lung Cancer Cell Invasion through Upregulation of MMP9 Expression Depending on Notch Signaling

The transmembrane and secreted protein delta-like 1 homolog (DLK1) belongs to the EGF-like family. It is widely accepted that DLK1 plays important roles in regulating cell differentiation, such as adipogenesis and osteogenesis. Aberrant expression of DLK1 has been found in various types of human cancers, including lung cancer. A previous study in this lab has revealed that DLK1 is associated with tumor invasion, although the mechanism is still unknown. To explore the potential effects that DLK1 might have on invasion, DLK1 was overexpressed or knocked down in the human lung cancer cell lines. The proteins influences on cell invasion were subsequently evaluated. A transwell assay showed that DLK1 overexpression significantly promoted cancer cell invasion. Western blotting and gelatin zymography analysis indicated that DLK1 could affect both matrix metalloproteinase-9 (MMP9) expression and its extracellular activity. An analysis of NOTCH1 and HES1 gene expression and Notch intracellular domain (NICD) nuclear translocation during DLK1 stimulation or depletion demonstrated that DLK1 could activate Notch signaling in lung cancer cells. Additionally, the elevated expression of MMP9 induced by DLK1 stimulation could be significantly decreased by inhibiting Notch signaling using γ-secretase inhibitor (GSI). The data presented in this study suggest that DLK1 can promote the invasion of lung cancer cells by upregulating MMP9 expression, which depends on Notch signaling.

A cancer/testis antigen microarray to screen autoantibody biomarkers of non-small cell lung cancer

Cancer/testis antigens (CTAs) are highly immunogenic in many tumors, especially in non-small cell lung cancer (NSCLC). A low-density protein microarray, which consisted of 72 CTAs and six non-CTAs, was used to screen for lung cancer-related autoantibodies. The CTA panel of NY-ESO-1, XAGE-1, ADAM29 and MAGEC1, had sensitivity and specificity values of 33% and 96%, respectively. When examined in a test set, this panel of markers had sensitivity and specificity values of 36% and 89%, respectively. This array of markers preferentially detected NSCLC, but did not detect breast cancer, and non-cancer lung disease.

Deletion of tumor suppressor genes in Chinese non-small cell lung cancer

In the present study, we used 22 microsatellite markers flanking to or within 13 known or candidate tumor suppressor genes (TSGs) to detect loss of heterozygosity (LOH) in these chromosomal regions among 41 cases of non-small cell lung cancer, including 28 squamous cell carcinoma (SCC) and 13 adenocarcinoma (ADC). The studied TSGs comprised FHIT, VHL, APC, PRLTS, p16, IFNA, PTEN, p57, ATM, p53, BRCA1, DPC4 and DCC. Our data demonstrated frequent allelic losses of FHIT, p53, IFNA, VHL and p16 in both SCC and ADC. PTEN and ATM showed the least frequency of LOH, while no deletion of BRCA1 was detected in all tumor samples. LOH analysis of PRLTS was extended to 26 cases of ADC, which demonstrated significantly higher frequency of LOH than SCC. Our data indicated a possible correlation between specific TSG(s) and either histological type of lung cancer, and more attention should be paid to the PRLTS gene, which might play an important role in the development of ADC.

The ovarian cancer‐derived secretory/releasing proteome: A repertoire of tumor markers

Ovarian cancer is the most lethal gynecological malignancy worldwide, and early detection of this disease using serum or plasma biomarkers may improve its clinical outcome. In the present study, a large scale protein database derived from ovarian cancer was created to enable tumor marker discovery. First, primary organ cultures were established with the tumor tissues and corresponding normal tissues obtained from six ovarian cancer patients, and the serum‐free conditioned medium (CM) samples were collected for proteomic analysis. The total proteins from the CM sample were separated by SDS‐PAGE, digested with trypsin and then analyzed by LC‐MS/MS. Combining data from the tumor tissues and the normal tissues, 1129 proteins were identified in total, of which those categorized as “extracellular proteins” and “plasma membrane proteins” accounted for 21.4% and 16.9%, respectively. For validation, three secretory proteins (NID1, TIMP2, and VCAN) involved in “organ development”‐associated subnetwork, showed significant differences between their levels in the circulating plasma samples from ovarian cancer patients and healthy women. In conclusion, this ovarian cancer‐derived protein database provides a credible repertoire of potential biomarkers in blood for this malignant disease, and deserves mining further.

Overexpression of OLC1, Cigarette Smoke, and Human Lung Tumorigenesis

BACKGROUND Exposure to cigarette smoke is a major risk factor for lung cancer, but how it induces cancer is unclear. The overexpressed in lung cancer 1 (OLC1) gene is one of 50 candidate lung cancer genes identified by suppression subtractive hybridization as having higher expression in squamous cell carcinoma (SCC) than normal lung epithelia. METHODS We used immunohistochemistry (IHC) to measure OLC1 protein levels in primary lung cancer samples from 559 patients and used fluorescence in situ hybridization to measure OLC1 copy number in primary SCC samples from 23 patients. We compared OLC1 protein expression in SCC samples of 371 patients with and without a smoking history using the Pearson chi(2) test. We assayed OLC1 protein levels by immunoblotting in H1299 human lung cancer cells, immortalized human bronchial epithelial cells, and primary cultured normal human bronchial epithelial cells that were treated with cigarette smoke condensate. We assayed tumor formation in athymic mice using NIH3T3 mouse fibroblast cells transfected with OLC1 (eight mice) and analyzed apoptosis and colony formation of H1299 and H520 lung cancer cells transfected with scrambled (negative) or OLC1 small interfering RNAs (siRNAs) (s1). RESULTS OLC1 protein was overexpressed in 387 of 464 (83.4%) of primary lung cancers, as detected by IHC, and OLC1 was amplified in 14 of 23 (60%) of SCC samples. OLC1 protein overexpression was more common in SCC patients with a smoking history than those without (77.1% vs 45.8%, P < .001). In addition, cigarette smoke condensate increased OLC1 protein levels in H1299 cells, immortalized human bronchial epithelial cells, and primary cultured normal human bronchial epithelial cells. Overexpression of OLC1 induced tumor formation in athymic mice (control vs OLC1, 0% vs 100%). Knockdown of OLC1 increased apoptosis (mean percentage of apoptotic H1299 cells, s1 vs negative: 30.3% vs 6.4%, difference = 23.9%, 95% confidence interval [CI] = 19.1% to 28.5%, P = .002; mean percentage of apoptotic H520 cells, s1 vs negative: 21.6% vs 4.9%, difference = 16.7%, 95% CI = 10.6% to 22.8%, P = .007) and decreased colony formation (mean no. of colonies of H1299 cells transfected with siRNAs, negative vs s1: 84 vs 4, difference = 80, 95% CI = 71 to 88, P < .001; mean no. of colonies of H520 cells transfected with siRNAs, negative vs s1: 103 vs 24, difference = 79, 95% CI = 40 to 116, P = .005). CONCLUSIONS OLC1 is a candidate oncogene in lung cancer whose expression may be regulated by exposure to cigarette smoke.

Secretory/releasing proteome-based identification of plasma biomarkers in HBV-associated hepatocellular carcinoma

For successful therapy, hepatocellular carcinoma (HCC) must be detected at an early stage. Herein, we used a proteomic approach to analyze the secretory/releasing proteome of HCC tissues to identify plasma biomarkers. Serum-free conditioned media (CM) were collected from primary cultures of cancerous tissues and surrounding noncancerous tissues. Proteomic analysis of the CM proteins permitted the identification of 1365 proteins. The enriched molecular functions and biological processes of the CM proteins, such as hydrolase activity and catabolic processes, were consistent with the liver being the most important metabolic organ. Moreover, 19% of the proteins were characterized as extracellular or membrane-bound. For validation, secretory proteins involved in transforming growth factor-β signaling pathways were validated in plasma samples. Alphafetoprotein (AFP), metalloproteinase (MMP)1, osteopontin (OPN), and pregnancy-specific beta-1-glycoprotein (PSG)9 were significantly increased in HCC patients. The overall performance of MMP1 and OPN in the diagnosis of HCC remained greater than that of AFP. In addition, this study represents the first report of MMP1 as a biomarker with a higher sensitivity and specificity than AFP. Thus, this study provides a valuable resource of the HCC secretome with the potential to investigate serological biomarkers. MMP1 and OPN could be used as novel biomarkers for the early detection of HCC and to improve the sensitivity of biomarkers compared with AFP.

Metastatic potential of lung squamous cell carcinoma associated with HSPC300 through its interaction with WAVE2

The small protein, HSPC300 (haematopoietic stem/progenitor cell protein 300), is associated with reorganization of actin filaments and cell movement, but its activity has not been reported in human cancer cells. Here, we investigated the association of HSPC300 expression with clinical features of lung squamous cell carcinoma. High levels of HSPC300 protein were detected in 84.1% of tumour samples, and in 30.8% of adjacent morphologically normal tissues. The number of primary tumours with elevated HSPC300 levels was significantly higher in primary tumours with lymph node metastases as opposed to those without, and also in tumours from patients with more advanced disease. HSPC300 modulates the morphology and motility of cells, as siRNA knockdown caused the reorganization of actin filaments, decreased the formation of pseudopodia, and inhibited the migration of a lung cancer cell line. We further showed that HSPC300 interacted with the WAVE2 protein, and HSPC300 silencing resulted in the degradation of WAVE2 in vitro. HSPC300 and WAVE2 were co-expressed in approximately 85.7% of primary tumours with lymph node metastases. We hypothesize that HSPC300 is associated with metastatic potential of lung squamous cell carcinoma through its interaction with WAVE2.