Syntaxin4-Munc18c Interaction Promotes Breast Tumor Invasion and Metastasis by Regulating MT1-MMP Trafficking

Invasion of neighboring extracellular matrix (ECM) by malignant tumor cells is a hallmark of metastatic progression. This invasion can be mediated by subcellular structures known as invadopodia, the function of which depends upon soluble N-ethylmaleimide-sensitive factor-activating protein receptor (SNARE)-mediated vesicular transport of cellular cargo. Recently, it has been shown the SNARE Syntaxin4 (Stx4) mediates trafficking of membrane type 1-matrix metalloproteinase (MT1-MMP) to invadopodia, and that Stx4 is regulated by Munc18c in this context. Here, it is observed that expression of a construct derived from the N-terminus of Stx4, which interferes with Stx4-Munc18c interaction, leads to perturbed trafficking of MT1-MMP, and reduced invadopodium-based invasion in vitro, in models of triple-negative breast cancer (TNBC). Expression of Stx4 N-terminus also led to increased survival and markedly reduced metastatic burden in multiple TNBC models in vivo. The findings are the first demonstration that disrupting Stx4-Munc18c interaction can dramatically alter metastatic progression in vivo, and suggest that this interaction warrants further investigation as a potential therapeutic target.

IMPLICATIONS

Disrupting the interaction of Syntaxin4 and Munc18c may be a useful approach to perturb trafficking of MT1-MMP and reduce metastatic potential of breast cancers.

Sleeping with the enemy? A randomized controlled trial of a collaborative health authority/industry intervention to influence prescribing practice

AIMS

To evaluate the effectiveness of a health authority/pharmaceutical company collaborative intervention to influence the choice of proton pump inhibitors

METHODS

Randomized controlled trial, with general practices forming the unit of allocation and analysis.

RESULTS

Constructive working relationships were achieved with five of six pharmaceutical companies involved. One hundred and two out of 140 practitioners in intervention group practices received at least one visit from an industry representative. There were no reports of representatives operating outside their agreed remit. Prescribing in both the intervention and control group moved towards that recommended by the guidelines but there was no difference between the groups in either the proportion of prescriptions in line with the guidelines or the overall cost.

CONCLUSIONS

Health authorities can achieve professional working relationships with the pharmaceutical industry although no changes in practice attributable to the intervention are achieved. Further work is required to develop effective means to influence prescribing in line with independent guidelines especially in the context of the development of Primary Care Groups.

Primary care. Finding poll position

There are major governance issues for primary care trusts which need to be addressed now. Greater accountability to the community is needed. There should be clear and rapid moves towards a democratic model. Electing a third of board members every year for three years, with participation by the local population, would improve democratic accountability.

Transferring the costs of expensive treatments from secondary to primary care

General practitioners, especially fundholders, are becoming increasingly concerned about being asked to prescribe treatments for their patients that are outside their therapeutic experience. They are concerned about the clinical responsibility for such prescribing and the effects on their budgets. In some specialties transferring the costs of expensive treatments from secondary to primary care (cost shifting) has become partly institutionalised because of the separate sources of funding for drugs prescribed in the two sectors. With increased efforts to control the rising costs of the drugs budget and the emergence of new expensive treatments, cost shifting will be a challenge to clinicians and purchasers as they strive for rational, cost effective prescribing. A review of the funding mechanisms for drugs prescribing and of the relation between the licensing process and the decision to support the use of a treatment in primary or secondary care is needed.

Towards a formalization of quality in health care contracts

The paper explores ways of how measurable indicators of quality of health care might be specified in health care contracts of NHS providers. The paper assesses the likelihood of defining formal outcome-related indicators. If outcome-related indicators are not measurable, then process or input-related quality indicators should be used as a second best choice. These should have certain desirable properties. The paper spells out these properties and points to examples.

How contracting will force us to ask questions we never asked before

This paper examines the impact of the separation of the purchaser from the provider and in particular the effects of placing service contracts. The paper assumes the role of the purchaser authority and examines some of the questions and assumptions that will influence the type of work to be purchased.