The SH3–SAM Adaptor HACS1 is Up-regulated in B Cell Activation Signaling Cascades

HACS1 is a Src homology 3 and sterile alpha motif domain–containing adaptor that is preferentially expressed in normal hematopoietic tissues and malignancies including myeloid leukemia, lymphoma, and myeloma. Microarray data showed HACS1 expression is up-regulated in activated human B cells treated with interleukin (IL)-4, CD40L, and anti–immunoglobulin (Ig)M and clustered with genes involved in signaling, including TNF receptor–associated protein 1, signaling lymphocytic activation molecule, IL-6, and DEC205. Immunoblot analysis demonstrated that HACS1 is up-regulated by IL-4, IL-13, anti-IgM, and anti-CD40 in human peripheral blood B cells. In murine spleen B cells, Hacs1 can also be up-regulated by lipopolysaccharide but not IL-13. Induction of Hacs1 by IL-4 is dependent on Stat6 signaling and can also be impaired by inhibitors of phosphatidylinositol 3-kinase, protein kinase C, and nuclear factor κB. HACS1 associates with tyrosine-phosphorylated proteins after B cell activation and binds in vitro to the inhibitory molecule paired Ig-like receptor B. Overexpression of HACS1 in murine spleen B cells resulted in a down-regulation of the activation marker CD23 and enhancement of CD138 expression, IgM secretion, and Xbp-1 expression. Knock down of HACS1 in a human B lymphoma cell line by small interfering ribonucleic acid did not significantly change IL-4–stimulated B cell proliferation. Our study demonstrates that HACS1 is up-regulated by B cell activation signals and is a participant in B cell activation and differentiation

Second Autologous Stem Cell Transplantation as Salvage Therapy for Multiple Myeloma: Impact on Progression-Free and Overall Survival

The role of a second autologous stem cell transplant (ASCT) as salvage therapy is unclear, particularly with the availability of novel agents to treat progressive multiple myeloma (MM). We retrospectively reviewed all MM patients who received a second ASCT as salvage therapy at our center from March 1992 to December 2009. Eighty-one MM patients received a second ASCT for relapsed MM. The median time to relapse after first transplant was 39 months (9.83-100). All patients received reinduction therapy before the second ASCT. The high-dose regimen given before the second ASCT consisted of melphalan (MEL) alone in the majority. Complete response, very good partial response, and partial response were seen in 7.7%, 39.7%, and 50%, respectively, at day 100 post-ASCT; the median time to relapse after the second ASCT was 19 months. Early deaths occurred in 2.6%. Median progression-free survival (PFS) based on the time to myeloma relapse after first ASCT was 9.83 months (relapse ≤24 months) and 17.3 months (relapse ≥24 months) (P < .05). Median overall survival (OS) was 28.47 months (relapse ≤24 months) and 71.3 months (relapse >24 months) (P = .006). Second ASCT is a feasible and safe option for salvage therapy in MM. The best outcome was observed in patients whose time to progression was >24 months after first ASCT, as these patients had a subsequent PFS lasting over 1 year and an OS of almost 6 years