Mutant p53 drives invasion by promoting integrin recycling.

p53 is a tumor suppressor protein whose function is frequently lost in cancers through missense mutations within the Tp53 gene. This results in the expression of point-mutated p53 proteins that have both lost wild-type tumor suppressor activity and show gain of functions that contribute to transformation and metastasis. Here, we show that mutant p53 expression can promote invasion, loss of directionality of migration, and metastatic behavior. These activities of p53 reflect enhanced integrin and epidermal growth factor receptor (EGFR) trafficking, which depends on Rab-coupling protein (RCP) and results in constitutive activation of EGFR/integrin signaling. We provide evidence that mutant p53 promotes cell invasion via the inhibition of TAp63, and simultaneous loss of p53 and TAp63 recapitulates the phenotype of mutant p53 in cells. These findings open the possibility that blocking alpha5/beta1-integrin and/or the EGF receptor will have therapeutic benefit in mutant p53-expressing cancers.

Prognostic biomarkers of IFNb therapy in multiple sclerosis patients.

BACKGROUND: Interferon beta (IFNb) reduces relapse frequency and disability progression in patients with multiple sclerosis (MS). OBJECTIVES: Early identification of prognostic biomarkers of IFNb-treated patients will allow more effective management of MS. METHODS: The IMPROVE study evaluated subcutaneous IFNb versus placebo in 180 patients with relapsing-remitting MS. Magnetic resonance imaging scans, clinical assessments, and blood samples were obtained at baseline and every 4 weeks from every participant. Thirty-nine biomarkers (32 transcripts; seven proteins) were studied in 155 patients from IMPROVE. Therapeutic response was defined by absence of new combined unique lesions, relapses, and sustained increase in Expanded Disability Status Scale over 1 year. A machine learning approach was used to examine the association between biomarker expression and treatment response. RESULTS: While baseline levels of individual genes were relatively poor predictors, combinations of three genes were able to identify subjects with sub-optimal therapeutic responses. The triplet CASP2/IRF4/IRF6, previously identified in an independent dataset, was tested among other combinations. This triplet showed acceptable predictive accuracy (0.68) and specificity (0.88), but had relatively low sensitivity (0.22) resulting in an area under the curve (AUC) of 0.63. Other combinations of biomarkers resulted in AUC of up to 0.80 (e.g. CASP2/IL10/IL12Rb1). CONCLUSIONS: Baseline expression, or induction ratios, of specific gene combinations correlate with future therapeutic response to IFNb, and have the potential to be prognostically useful.

Identification of genes associated with tumorigenesis and metastatic potential of hypopharyngeal cancer by microarray analysis.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer among men in the developed world. There is a need, for both clinical and scientific reasons, to find markers to identify patients with aggressive disease as early as possible, and to understand the events leading to malignant transformation and susceptibility to metastasis. We report the first large-scale gene expression analysis of a unique HNSCC location, the hypopharynx. Four normal and 34 tumour samples were analysed with 12 600 gene microarrays. Clusters of differentially expressed genes were identified in the chromosomal regions 3q27.3, 17q21.2-q21.31, 7q11.22-q22.1 and 11q13.1-q13.3, which, interestingly, have already been identified by comparative genomic hybridization (CGH) as major regions of gene amplification. We showed that six overexpressed genes (EIF4G1, DVL3, EPHB4, MCM7, BRMS1 and SART1) located in these regions are indeed amplified. We report 119 genes that are highly differentially expressed between 'early' tumours and normal samples. Of these, we validated by quantitative PCR six novel poorly characterized genes. These genes are potential new markers of HNSCC. Comparing patients with relatively nonaggressive and aggressive tumours (without or with clinical evidence of metastasis 3 years after surgery), we identified 164 differentially expressed genes potentially involved in the acquisition of metastatic potential. This study contributes to the understanding of HNSCC, staging patients into prognostic groups and identifying high-risk patients who may benefit from more aggressive treatment.

PDEF promotes luminal differentiation and acts as a survival factor for ER-positive breast cancer cells.

Breast cancer is a heterogeneous disease and can be classified based on gene expression profiles that reflect distinct epithelial subtypes. We identify prostate-derived ETS factor (PDEF) as a mediator of mammary luminal epithelial lineage-specific gene expression and as a factor required for tumorigenesis in a subset of breast cancers. PDEF levels strongly correlate with estrogen receptor (ER)-positive luminal breast cancer, and PDEF transcription is inversely regulated by ER and GATA3. Furthermore, PDEF is essential for luminal breast cancer cell survival and is required in models of endocrine resistance. These results offer insights into the function of this ETS factor that are clinically relevant and may be of therapeutic value for patients with breast cancer treated with endocrine therapy.

Serum biomarkers for detection of breast cancers: A prospective study.

Using surface-enhanced laser desorption/ionization-time of flight (SELDI-TOF), Li et al. [Clin Chem 48(8): 1296-1304, 2002] identified 3 serum biomarkers, BC1 (4.3 kDa), BC2 (8.1 kDa) and BC3 (8.9 kDa), whose combination significantly detects breast cancer patients from non-cancer controls. This work aimed to validate these biomarkers in an independent prospective study. We screened 89 serum samples including 49 breast cancers at pT1-4N0M0 (n = 23), pT1-4N1-3M0 (n = 17) or pT1-4N0-3M1 (n = 9) stages, 13 benign breast diseases and 27 healthy women. The BC2 biomarker significance was not recovered. However, we found 2 peaks that we named BC1a (4286 Da) and BC1b (4302 Da), that could correspond to Li's BC1 since they significantly decrease in breast cancers (p < 0.00007 and p < 0.0002, respectively). Similarly, BC3a (8919 Da) and BC3b (8961 Da) are significantly increased in breast cancers (p < 0.02 and p < 0.0002, respectively) and could correspond to the Li's BC3. For each biomarker we defined stringent (no errors) and flexible (less than 10% errors) cut-off values and tested the power of the combined BC1a/BC1b/BC3a/BC3b stringent and flexible profiles to discriminate breast cancers. They identified 33% and 45% cancers, respectively. Applied to the same series, Ca 15.3 test identified 22% patients. Interestingly, in association with the BC1a/BC1b/BC3a/BC3b profiles, Ca 15.3 improved the number of detected cancers indicating that it is an independent parameter. Collectively, our data partially validate those of Li's study and confirm that the BC1 and BC3 biomarkers are helpful for breast cancer diagnosis.

Analysis of a novel human gene, LOC92912, over-expressed in hypopharyngeal tumours.

We have identified by differential display a number of novel genes that are expressed in hypopharyngeal head and neck squamous cell carcinoma. We report here the characterisation of one of these novel human genes, LOC92912, that encodes a protein of 375 amino acids. The protein contains a RWD domain, a coiled-coil, and an E2 ubiquitin conjugating enzyme domain. LOC92912 is upregulated in about 85% of tumour samples. It is expressed in tumour masses and in invasive epithelium, and is located in the cytoplasm of cells. To gain insights into its functions, we identified potential interacting partners by immunoaffinity purification of the flag tagged protein followed by MALDI peptide mass fingerprinting mass spectrometry. Actin and six actin-binding proteins were unambiguously identified as potential interacting partners, suggesting that LOC92912's functions may be linked with the cytoskeleton. This novel human gene may represent a new target for cancer therapeutics.