Microarray analysis of normal cervix, carcinoma in situ, and invasive cervical cancer: identification of candidate genes in pathogenesis of invasion in cervical cancer

The BNIP-2 and Cdc42GAP homology (BCH) domain of p50RhoGAP/Cdc42GAP sequesters RhoA from inactivation by the adjacent GTPase-activating protein domain

The BNIP-2 and Cdc42GAP Homology (BCH) domain from p50RhoGAP sequesters RhoA from inactivation by the adjacent GAP domain and it confers unique Rho-binding profile from that of GAP domain. This suppression is further augmented by an intramolecular interaction, adding to a new paradigm for regulating p50RhoGAP signaling.

The BNIP-2 and Cdc42GAP homology (BCH) domain is a novel regulator for Rho GTPases, but its impact on p50-Rho GTPase-activating protein (p50RhoGAP or Cdc42GAP) in cells remains elusive. Here we show that deletion of the BCH domain from p50RhoGAP enhanced its GAP activity and caused drastic cell rounding. Introducing constitutively active RhoA or inactivating GAP domain blocked such effect, whereas replacing the BCH domain with endosome-targeting SNX3 excluded requirement of endosomal localization in regulating the GAP activity. Substitution with homologous BCH domain from Schizosaccharomyces pombe, which does not bind mammalian RhoA, also led to complete loss of suppression. Interestingly, the p50RhoGAP BCH domain only targeted RhoA, but not Cdc42 or Rac1, and it was unable to distinguish between GDP and the GTP-bound form of RhoA. Further mutagenesis revealed a RhoA-binding motif (residues 85-120), which when deleted, significantly reduced BCH inhibition on GAP-mediated cell rounding, whereas its full suppression also required an intramolecular interaction motif (residues 169-197). Therefore, BCH domain serves as a local modulator in cis to sequester RhoA from inactivation by the adjacent GAP domain, adding to a new paradigm for regulating p50RhoGAP signaling.

Osteopontin expression correlates with invasiveness in cervical cancer

AIM

Osteopontin is a secreted, integrin-binding glycophosphoprotein that is overexpressed in many types of cancers and appears to be involved in carcinogenesis and cancer progression. To understand the role of osteopontin in carcinogenesis of cervical cancer, this study was designed to determine whether osteopontin is expressed in cervical cancer and carcinoma in situ (CIS) tissue as well as in normal cervical tissue.

METHODS

The expression of osteopontin was immunohistochemically analysed from 68 normal cervix, 55 CIS and 52 invasive cervical cancer tissues using a paraffin-embedded tissue array. Immunostaining was evaluated by intensity and the percentage of stained cells.

RESULTS

Osteopontin expression in normal, CIS and cervical cancer tissues was two of 68 (2.9%), 43 of 55 (78.2%) and 46 of 52 (88.4%), respectively (P < 0.01). High intensity (strong positive)/high proportion (more than 50%) staining seen in CIS and cervical cancer tissue samples was 45 of 55 (81.8%)/22 of 55 (40.0%) and 50 of 52 (96.2%)/31 of 52 (59.7%), respectively (P = 0.029 and P = 0.054). There was no significant correlation between the immunostaining score and stage and the immunostaining score and survival.

CONCLUSION

Osteopontin may have a potential use as a diagnostic factor for cervical cancer and osteopontin expression is closely correlated with carcinogenesis and invasion of cervical cancer.

Changes in gene expression predicting local control in cervical cancer: results from Radiation Therapy Oncology Group 0128

PURPOSE

To evaluate the potential of gene expression signatures to predict response to treatment in locally advanced cervical cancer treated with definitive chemotherapy and radiation.

EXPERIMENTAL DESIGN

Tissue biopsies were collected from patients participating in Radiation Therapy Oncology Group (RTOG) 0128, a phase II trial evaluating the benefit of celecoxib in addition to cisplatin chemotherapy and radiation for locally advanced cervical cancer. Gene expression profiling was done and signatures of pretreatment, mid-treatment (before the first implant), and "changed" gene expression patterns between pre- and mid-treatment samples were determined. The ability of the gene signatures to predict local control versus local failure was evaluated. Two-group t test was done to identify the initial gene set separating these end points. Supervised classification methods were used to enrich the gene sets. The results were further validated by leave-one-out and 2-fold cross-validation.

RESULTS

Twenty-two patients had suitable material from pretreatment samples for analysis, and 13 paired pre- and mid-treatment samples were obtained. The changed gene expression signatures between the pre- and mid-treatment biopsies predicted response to treatment, separating patients with local failures from those who achieved local control with a seven-gene signature. The in-sample prediction rate, leave-one-out prediction rate, and 2-fold prediction rate are 100% for this seven-gene signature. This signature was enriched for cell cycle genes.

CONCLUSIONS

Changed gene expression signatures during therapy in cervical cancer can predict outcome as measured by local control. After further validation, such findings could be applied to direct additional therapy for cervical cancer patients treated with chemotherapy and radiation.

Gene expression profiles of rat olfactory bulb at developmental stage

Microarray analysis may be a useful tool to identify some candidate genes related to the development of olfactory bulbs. In the present study, gene expression profiles of olfactory bulbs from postnatal day 1 (P1) rats and postnatal day 35 (P35) rats were analyzed by oligonucleotide-microarray and expression levels of some selected genes were also confirmed by RT-PCR and in situ hybridization. 9146 genes were commonly identified in six microarray chips. Among these genes, 76 were up-regulated and 130 were down-regulated three-folds or more at P1 olfactory bulbs. Out of these 76 up-regulated genes, 24 genes were annotated based on the NCBI database of reference sequences and expression levels of these 24 genes were confirmed by RT-PCR. Among them, 2 interesting genes (neurogenic differentiation 1 and retinoid acid receptor alpha) were localized in the P1 olfactory bulb by the use of in situ hybridization technique. Our results may provide basic information to identify genes associated with functional growth of olfactory bulbs.

Rho GTPases in cancer cell biology

Rho GTPases contribute to multiple cellular processes that could affect cancer progression, including cytoskeletal dynamics, cell cycle progression, transcriptional regulation, cell survival and vesicle trafficking. In vitro several Rho GTPases have oncogenic activity and/or can promote cancer cell invasion, and this correlates with increased expression and activity in a variety of cancers. Conversely, other family members appear to act as tumour suppressors and are deleted, mutated or downregulated in some cancers. Genetic models are starting to provide new information on how Rho GTPases affect cancer development and progression. Here, we discuss how Rho GTPases could contribute to different steps of cancer progression, including proliferation, survival, invasion and metastasis.