Nerves and availability of mesodermal cells are essential for the function of the segment addition zone (SAZ) during segment regeneration in polychaete annelids.

Most of annelids grow all over their asexual life through the continuous addition of segments from a special zone called "segment addition zone" (SAZ) adjacent to the posterior extremity called pygidium. Amputation of posterior segments leads to regeneration (posterior regeneration-PR) of the pygidium and a new SAZ, as well as new segments issued from this new SAZ. Amputation of anterior segments leads some species to regeneration (anterior regeneration-AR) of the prostomium and a SAZ which produces new segments postero-anteriorly as during PR.

Neural regulation of body polarities in nereid worm regeneration.

Nerve dependence in regeneration has been established more than 200 years ago but the mechanisms by which nerves are necessary to regeneration remain to be fully elucidated. Aside from their direct impact in stimulating cellular growth, nerves also have a role on the establishment of body polarities (antero-posterior and dorso-ventral patterns) and this has been particularly well studied in nereid annelid worms. Nereids can regenerate appendages (parapodia) and the tail (body segments).

Regulation of dorso-ventral polarity by the nerve cord during annelid regeneration: A review of experimental evidence.

An important goal for understanding regeneration is determining how polarity is conferred to the regenerate. Here we review findings in two groups of polychaete annelids that implicate the ventral nerve cord in assigning dorso-ventral polarity, and specifically ventral identity, to the regenerate. In nereids, surgical manipulations indicate that parapodia develop where dorsal and ventral body wall territories contact.

Nerve Dependence: From Regeneration to Cancer.

Nerve dependence has long been described in animal regeneration, where the outgrowth of axons is necessary to the reconstitution of lost body parts and tissue remodeling in various species. Recent discoveries have demonstrated that denervation can suppress tumor growth and metastasis, pointing to nerve dependence in cancer. Regeneration and cancer share similarities in regard to the stimulatory role of nerves, and there are indications that the stem cell compartment is a preferred target of innervation.

Normal breast epithelial cells induce p53-dependent apoptosis and p53-independent cell cycle arrest of breast cancer cells.

Cancer development depends not only on the nature of cancerous cells themselves, but also on the regulatory effects of various normal cells. The present study was performed to investigate the effect of normal breast epithelial cells (NBEC) on the growth of breast cancer cells under various conditions. We demonstrated that NBEC-conditioned medium (NBEC-CM) inhibited growth of breast cancer cell lines in monolayer culture and three-dimensional collagen gel culture, as well as in soft agar.