Galectin-3 (gal-3), a pleiotrophic protein, is an important regulator of tumor metastasis, which like β-catenin shuttles between the nucleus and the cytosol in a phosphorylation-dependent manner. We report herein that β-catenin stimulation of cyclin D1 and c-myc expression is gal-3 dependent. Gal-3 binds to β-catenin/Tcf complex, colocalizes with β-catenin in the nucleus, and induces the transcriptional activity of Tcf-4 as determined by the TOP/FOPFLASH reporter system. We have identified the β-catenin–gal-3–binding sequences, which are in the NH2 and COOH termini of the proteins encompassing amino acid residues 1 to 131 and 143 to 250, respectively. These data indicate that gal-3 is a novel binding partner for β-catenin involved in the regulation of Wnt/β-catenin signaling pathway.

Galectin-3 (Gal-3), a member of the β-galactoside binding protein family containing the NWGR antideath motif of the Bcl-2 protein family, is involved in various aspects of cancer progression. Previously, it has been shown that the antiapoptotic activity of Gal-3 is regulated by the phosphorylation at Ser⁶ by casein kinase 1 (CK1). Here we questioned how phosphorylation at Ser⁶ regulates Gal-3 function. We have generated serine-to-alanine (S6A) and serine-to-glutamic acid (S6E) Gal-3 mutants and transfected them into the BT-549 human breast carcinoma cell line, which does not express Gal-3. BT-549 cell clones expressing wild-type (wt) and mutant Gal-3 were exposed to chemotherapeutic anticancer drugs. In response to the apoptotic insults, phosphorylated wt Gal-3 was exported from the nucleus to the cytoplasm and protected the BT-549 cells from drug-induced apoptosis while nonphosphorylated mutant Gal-3 neither was exported from the nucleus nor protected BT-549 cells from drug-induced apoptosis. Furthermore, leptomycin B, a nuclear export inhibitor, increased the cisplatin-induced apoptosis of Gal-3 expressing BT-549 cells. These results suggest that Ser⁶ phosphoryaltion acts as a molecular switch for its cellular translocation from the nucleus to the cytoplasm and, as a result, regulates the antiapoptotic activity of Gal-3.

Sarcopenia, which is characterized by a decrease in muscle quantity or quality, is commonly observed in patients with cancer. Recent research has reported contradictory results on the association between sarcopenia and the efficacy of immune checkpoint inhibitors (ICIs). We conducted a systematic review and meta‐analysis to investigate this discrepancy. We systematically searched three electronic databases to identify articles reporting on the association between sarcopenia and treatment outcomes in patients with solid cancers who received ICIs. The outcomes assessed were hazard ratios (HRs) for overall survival (OS) and progression‐free survival (PFS), and odds ratios (ORs) for objective response rate (ORR), disease control rate (DCR), and toxicity. Pooled estimates and their 95% confidence intervals (CIs) were calculated. A total of 2501 patients from 26 studies were analysed. Sarcopenia was observed in 44.7% (95% CI: 38.2–51.3) of the patients and was significantly associated with poor survival (HR = 1.55, 95% CI = 1.32–1.82 for OS and HR = 1.61, 95% CI = 1.35 to 1.93 for PFS). The HRs (95% CIs) for OS according to the diagnostic measures used were 1.97 (0.88–4.41) for psoas muscle index (PMI), 1.41 (0.87–2.28) for skeletal muscle density (SMD), and 1.43 (1.23–1.67) for skeletal mass index (SMI). The HRs (95% CIs) for PFS were 1.86 (1.08–3.21) for PMI, 1.27 (0.94–1.71) for SMD, and 1.38 (1.11–1.71) for SMI. Poor radiological response to ICI therapy was observed in patients with sarcopenia (OR = 0.52, 95% CI = 0.34–0.80 for ORR and OR = 0.45, 95% CI = 0.30–0.67 for DCR). The ORs for ORR (95% CIs) were 0.56 (0.15–2.05) for PMI and 0.78 (0.56–1.09) for SMI. The oncologic outcomes associated with melanoma and non‐small cell lung cancer (NSCLC) were comparable with those observed overall (HR for OS = 2.02, 95% CI = 1.26–3.24 for melanoma and HR for OS = 1.61, 95% CI = 1.19–2.18 for NSCLC). In contrast, the occurrence of severe toxicity was not associated with sarcopenia (OR = 1.13, 95% CI = 0.51–2.52). Poor survival and poor response in patients with sarcopenia indicate a negative association between sarcopenia and efficacy of ICIs. Sarcopenia's predictive ability is consistent across various tumour types. For the selection of patients who may respond to ICIs pre‐therapeutically, the presence of sarcopenia should be assessed in clinical practice.