Potential role of LMP2 as an anti-oncogenic factor in human uterine leiomyosarcoma: morphological significance of calponin h1

Profiling of GABAA and GABAB receptor expression in the myometrium of the human uterus

AIMS

γ-aminobutyric acid (GABA) mediates its physiological effects through the GABA_A and GABA_B receptors. In this study the putative expression of GABA_AR and GABA_BR subunits in human myometrium tissue was investigated.

MAIN METHODS

The expression levels of the 19 GABA_AR subunits (α₁-α₆, β₁-β₃, γ₁-γ₃, δ, ε, π, θ, ρ₁-ρ₃) and the three GABA_BR subunits (GABA_B1a, GABA_B1b, GABA_B2) were characterized by RT-qPCR analysis on two commercial samples and six samples derived from surgically removed myometrial tissues from different women. We probed for functional GABA_AR expression in primary human myometrial smooth muscle cells (HMSMCs) by whole-cell patch-clamp electrophysiology.

KEY FINDINGS

The absolute mRNA levels of the 22 GABA_AR and GABA_BR genes varied considerably across the eight samples, but a pronounced overlap existed between the specific subunits detected in the samples, with α₂, β₂, β₃, ε, π, θ, GABA_B1a and GABA_B1b mRNAs being detected in most samples. The expression profile of GABA_AR and GABA_BR subunit mRNAs in HMSMCs correlated with that observed in the eight tissue samples, albeit the subunit transcripts were detected at lower relative levels. Neither muscimol nor GABA evoked significant currents in these cells in the patch-clamp recordings.

SIGNIFICANCE

While the expression of the GABA_B1 subunits on their own is unlikely to give rise to functional GABA_BR expression, the GABA_AR subunits identified at mRNA level would be able to form functional receptors in the human myometrial tissue. Although GABA_AR-mediated currents could not be recorded from HMSMCs in this study, this suggests a role for GABAergic transmission in the human myometrium.

Biological characterization of soft tissue sarcomas

Soft tissue sarcomas are neoplastic malignancies that typically arise in tissues of mesenchymal origin. The identification of novel molecular mechanisms leading to mesenchymal transformation and the establishment of new therapies and diagnostic biomarker has been hampered by several critical factors. First, malignant soft tissue sarcomas are rarely observed in the clinic with fewer than 15,000 newly cases diagnosed each year in the United States. Another complicating factor is that soft tissue sarcomas are extremely heterogeneous as they arise in a multitude of tissues from many different cell lineages. The scarcity of clinical materials coupled with its inherent heterogeneity creates a challenging experimental environment for clinicians and scientists. Faced with these challenges, there has been extremely limited advancement in clinical treatment options available to patients as compared to other malignant tumours. In order to glean insight into the pathobiology of soft tissue sarcomas, scientists are now using mouse models whose genomes have been specifically tailored to carry gene deletions, gene amplifications, and somatic mutations commonly observed in human soft tissue sarcomas. The use of these model organisms has been successful in increasing our knowledge and understanding of how alterations in relevant oncogenic and/or tumour suppressive signal cascades, i.e., interferon-γ (IFN-γ), tumour protein 53 (TP53) and/or retinoblastoma (RB) pathway directly impact sarcomagenesis. It is the goal of many in the physiological community that the use of several mouse models will serve as powerful in vivo tools for further understanding of sarcomagenesis and potentially identify new diagnostic biomarker and therapeutic strategies against human soft tissue sarcomas.

Myoepithelial cell differentiation markers in ductal carcinoma in situ progression

We describe a preclinical model that investigates progression of early-stage ductal carcinoma in situ (DCIS) and report that compromised myoepithelial cell differentiation occurs before transition to invasive disease. Human breast cancer MCF10DCIS.com cells were delivered into the mouse mammary teat by intraductal injection in the absence of surgical manipulations and accompanying wound-healing confounders. DCIS-like lesions developed throughout the mammary ducts with full representation of human DCIS histologic patterns. Tumor cells were incorporated into the normal mammary epithelium, developed ductal intraepithelial neoplasia and DCIS, and progressed to invasive carcinoma, suggesting the model provides a rigorous approach to study early stages of breast cancer progression. Mammary glands were evaluated for myoepithelium integrity with immunohistochemical assays. Progressive loss of the myoepithelial cell differentiation markers p63, calponin, and α-smooth muscle actin was observed in the mouse myoepithelium surrounding DCIS-involved ducts. p63 loss was an early indicator, calponin loss intermediate, and α-smooth muscle actin a later indicator of compromised myoepithelium. Loss of myoepithelial calponin was specifically associated with gain of the basal marker p63 in adjacent tumor cells. In single time point biopsies obtained from 16 women diagnosed with pure DCIS, a similar loss in myoepithelial cell markers was observed. These results suggest that further research is warranted into the role of myoepithelial cell p63 and calponin expression on DCIS progression to invasive disease.

Expression of CAVEOLIN 1 in uterine mesenchymal tumors: No relationship between malignancy and CAVEOLIN 1 expression

Although most smooth muscle neoplasms detected in the human uterus are benign, uterine leiomyosarcoma (Ut-LMS) is extremely malignant with high rates of recurrence and metastasis. CAVEOLIN 1 (CAV1) levels in the epithelial cells of some carcinomas have been reported to increase during tumor progression. We herein evaluated the relationship between CAV1 expression and the pathological features of patients diagnosed with uterine mesenchymal tumors at several clinical facilities. No clinical link was observed between CAV1 expression and the malignancy of human uterine mesenchymal tumors. CAV1 expression was decreased in the normal myometrium, whereas it was strongly expressed in uterine mesenchymal tumors. However, the expression of CAV1 was not a potential biomarker to distinguish Ut-LMS from other types of uterine mesenchymal tumors. The perivascular expression of CAV1 was clearly observed in all types of uterine mesenchymal tumors and myometria. Therefore, the results of the present study suggest that CAV1 may not act as a potential biomarker of uterine malignant mesenchymal tumors.