Non-surgical treatment for ductal carcinoma in situ of the breasts - a prospective study on patient's perspective

LncRNA IPW inhibits growth of ductal carcinoma in situ by downregulating ID2 through miR-29c

BACKGROUND

Ductal carcinoma in situ (DCIS) of breast is the noninvasive lesion that has propensity to progress to the malignant form. At present, it is still unknown which lesions can potentially progress to invasive forms. In this study, we aimed to identify key lncRNAs involved in DCIS growth.

METHODS

We employ disease-related lncProfiler array to identify IPW in specimens of DCIS and matching control samples and validate the observations in three DCIS-non-tumorigenic cell lines. Further, we examine the mechanism of IPW action and the downstream signaling in in vitro and in vivo assays. Importantly, we screened a library containing 390 natural compounds to identify candidate compound selectively inhibiting IPW low DCIS cells.

RESULTS

We identified lncRNA IPW as a novel tumor suppressor critical for inhibiting DCIS growth. Ectopic expression of IPW in DCIS cells strongly inhibited cell proliferation, colony formation and cell cycle progression while silencing IPW in primary breast cells promoted their growth. Additionally, orthotropic implantation of cells with ectopic expression of IPW exhibited decreased tumor growth in vivo. Mechanistically, IPW epigenetically enhanced miR-29c expression by promoting H3K4me3 enrichment in its promoter region. Furthermore, we identified that miR-29c negatively regulated a stemness promoting gene, ID2, and diminished self-renewal ability of DCIS cells. Importantly, we screened a library containing 390 natural compounds and identified toyocamycin as a compound that selectively inhibited the growth of DCIS with low expression of IPW, while it did not affect DCIS with high IPW expression. Toyocamycin also suppressed genes associated with self-renewal ability and inhibited DCIS growth in vivo.

CONCLUSION

Our findings revealed a critical role of the IPW-miR-29c-ID2 axis in DCIS formation and suggested potential clinical use of toyocamycin for the treatment of DCIS.

[Therapeutic de-escalation in breast cancer surgery]

The surgical management of breast cancer has been marked by a therapeutic de-escalation from radical surgery to breast conservation and from axillary curage to sentinel lymph node sampling. With regard to breast surgery, the de-escalation of treatment has been largely due to organized screening, which has made it possible to diagnose tumors of smaller volume or at an earlier stage. The indications for conservative surgery have been broadened by the addition of radiotherapy on one hand, and the introduction of adjuvant and neo-adjuvant treatments on the other hand. In an effort to de-escalate surgery, totally non-invasive techniques such as radiofrequency, HIFU (High Intensity Focused Ultrasound) or cryotherapy have been tested. Currently, three trials are underway to evaluate active surveillance, without surgery, in the management of certain low-risk ductal carcinomas in situ (DCIS). Regarding axillary procedures, the sentinel node technique has allowed axillary staging in patients with early breast cancer without clinical or radiological lymph node involvement. Currently, international recommendations (ASCO, NCCN) and the consensus of experts in St Gallen do not recommend additional curage in cases of macro or micrometastatic invasion of the sentinel lymph nodes if the criteria of ACOSOG Z0011 are met. The question now arises as to the relevance of a biopsy of suspected axillary nodes during the initial workup and the usefulness of the sentinel node technique in the case of a negative initial workup.