VAV2 signaling promotes regenerative proliferation in both cutaneous and head and neck squamous cell carcinoma.

Regenerative proliferation capacity and poor differentiation are histological features usually linked to poor prognosis in head and neck squamous cell carcinoma (hnSCC). However, the pathways that regulate them remain ill-characterized. Here, we show that those traits can be triggered by the RHO GTPase activator VAV2 in keratinocytes present in the skin and oral mucosa. VAV2 is also required to maintain those traits in hnSCC patient-derived cells. This function, which is both catalysis- and RHO GTPase-dependent, is mediated by c-Myc- and YAP/TAZ-dependent transcriptomal programs associated with regenerative proliferation and cell undifferentiation, respectively. High levels of VAV2 transcripts and VAV2-regulated gene signatures are both associated with poor hnSCC patient prognosis. These results unveil a druggable pathway linked to the malignancy of specific SCC subtypes.

Pathophysiological mechanisms underlying a rat model of triple whammy acute kidney injury.

Simultaneous administration of certain antihypertensive (renin-angiotensin system inhibitors and diuretics) and nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with a renal toxicity syndrome known as "triple whammy" acute kidney injury (TW-AKI), yet poorly characterized at the pathophysiological level, as no specific experimental model exists on which to conduct preclinical research. Herein, we generated and characterized a rat model of TW-AKI (0.7 mg/kg/day trandolapril +400 mg/kg/day ibuprofen +20 mg/kg/day furosemide). Double treatments involving the NSAID caused a subclinical acute kidney injury, as they reduced glomerular filtration rate to a significant but not sufficient extent to increase Crpl concentration. Only the triple treatment generated an overt AKI with increased Crpl provided that animals were under partial water ingestion restriction. Histological examination revealed no evidence of tissue renal injury, and no proteinuria or makers of renal damage were detected in the urine. These findings, along with a normal fractional excretion of sodium and glucose, indicated that these drug combinations produce a prerenal type of AKI. In fact, blood pressure and renal blood flow were also reduced (most markedly following the triple combination), although renal dysfunction was more pronounced than expected for the corresponding pressure drop, supporting a key pathological role of the interference with renal autoregulation mechanisms. In summary, prerenal TW-AKI only occurs when volemia is challenged (i.e., by furosemide in partially water-deprived animals) under the effects of renin-angiotensin system inhibitors and NSAIDs. This model will facilitate further pathophysiological knowledge for a better diagnosis and clinical handling of this syndrome.

Vav2 pharmaco-mimetic mice reveal the therapeutic value and caveats of the catalytic inactivation of a Rho exchange factor.

The current paradigm holds that the inhibition of Rho guanosine nucleotide exchange factors (GEFs), the enzymes that stimulate Rho GTPases, can be a valuable therapeutic strategy to treat Rho-dependent tumors. However, formal validation of this idea using in vivo models is still missing. In this context, it is worth remembering that many Rho GEFs can mediate both catalysis-dependent and independent responses, thus raising the possibility that the inhibition of their catalytic activities might not be sufficient per se to block tumorigenic processes. On the other hand, the inhibition of these enzymes can trigger collateral side effects that could preclude the practical implementation of anti-GEF therapies. To address those issues, we have generated mouse models to mimic the effect of the systemic application of an inhibitor for the catalytic activity of the Rho GEF Vav2 at the organismal level. Our results indicate that lowering the catalytic activity of Vav2 below specific thresholds is sufficient to block skin tumor initiation, promotion, and progression. They also reveal that the negative side effects typically induced by the loss of Vav2 can be bypassed depending on the overall level of Vav2 inhibition achieved in vivo. These data underscore the pros and cons of anti-Rho GEF therapies for cancer treatment. They also support the idea that Vav2 could represent a viable drug target.

Immunophenotypic identification and characterization of tumor cells and infiltrating cell populations in meningiomas.

Meningiomas are primary tumors of the central nervous system composed of both neoplastic and other infiltrating cells. We determined the cellular composition of 51 meningioma samples by multiparameter flow cytometric (MFC) immunophenotyping and investigated the potential relationship between mRNA and protein expression levels of neoplastic cells. For immunophenotypic, morphologic, and cytogenetic characterization of individual cell populations, a large panel of markers was used together with phagocytic/endocytic functional assays and MFC sorting. Overall, our results revealed coexistence of CD45(-) neoplastic cells and CD45(+) immune infiltrating cells in all meningiomas. Infiltrating cells included tissue macrophages, with an HLA-DR(+)CD14(+)CD45(+)CD68(+)CD16(-/+)CD33(-/+) phenotype and high phagocytic/endocytic activity, and a small proportion of cytotoxic lymphocytes (mostly T CD8(+) and natural killer cells). Tumor cells expressed multiple cell adhesion proteins, tetraspanins, HLA-I/HLA-DR molecules, complement regulatory proteins, cell surface ectoenzymes, and growth factor receptors. Noteworthy, the relationship between mRNA and protein levels was variable, depending on the proteins evaluated and the level of infiltration by immune cells. In summary, our results indicate that MFC immunophenotyping provides a reliable tool for the characterization of the patterns of protein expression of different cell populations coexisting in meningioma samples, with a more accurate measure of gene expression profiles of tumor cells at the functional/protein level than conventional mRNA microarray, independently of the degree of infiltration of the tumor by immune cells.

Her-2/neu gene amplification in familial vs sporadic breast cancer. Impact on the behavior of the disease.

We compared the incidence of Her-2/neu amplification in patients with and without a family history of breast cancer and correlated gene status with clinicobiologic and prognostic features in sporadic and familial cases. Of 108 patients, 28.7% had gene amplification. Among 96 cases with family history information available, 28 had an affected first-degree relative. The gene was amplified more frequently in familial than in sporadic cases (13/28 [46%] vs 14/68 [21%]; P = .01). Among familial cases, amplification was associated with adverse clinicobiologic features (poorly differentiated tumors [P = .05], larger tumors [P = .05], more lymph nodes involved [P = .04], and DNA aneuploid [P = .02] and highly proliferative tumors [P = .005]), and the relapse (P = .02) and disease-related death (P = .05) rates were higher than in cases without amplification. Among sporadic cases, amplification was not associated with significantly different disease features, except for a higher incidence of DNA aneuploid tumors (P = .01), percentage of S-phase tumor cells (P = .006), and lower proportion of estrogen (P = .001) and progesterone (P = .002) receptors. Her-2/neu amplification was observed more frequently among patients with a family history of breast cancer, in whom it was associated with adverse clinicobiologic features and a worse clinical outcome.

Frequent E-cadherin gene inactivation by loss of heterozygosity in pleomorphic lobular carcinoma of the breast.

Pleomorphic lobular carcinoma of the breast is a variant of infiltrating lobular carcinoma that has poor prognosis. The pleomorphic appearance of this variant hinders its correct identification and differentiation from ductal carcinoma. The analysis of E-cadherin glycoprotein expression is a powerful tool for distinguishing lobular from ductal carcinomas, because complete loss of E-cadherin expression occurs in most infiltrating lobular tumors and lobular carcinomas in situ, but not in ductal tumors. In the present study, we have evaluated E-cadherin expression by immunohistochemistry in a series of 29 pleomorphic lobular breast carcinomas, including 7 cases with an in situ component. Complete loss of E-cadherin expression was observed in all the cases (29/29, 100%), in invasive and in situ components. To understand better the mechanisms underlying E-cadherin inactivation in this tumor type, the frequency of loss of heterozygosity at the E-cadherin gene locus (16q22.1) was analyzed. All informative tumors (27/27, 100%) showed loss of heterozygosity, thus implying a strong association between loss of E-cadherin expression and loss of heterozygosity at 16q22.1. Moreover, loss of heterozygosity was detected in all in situ components analyzed. These results imply that in terms of E-cadherin inactivation, pleomorphic lobular tumors are identical to classic infiltrating lobular carcinomas and distinct from ductal tumors, and therefore they should be considered a variant of lobular carcinoma of the breast, despite their aggressive behavior.