Purpose: Betulinic acid, a naturally occurring pentacyclic triterpenoid, exhibits potent antitumor activities, whereas the underlying mechanisms remain unclear. In the current study, we sought to determine the role and regulation of lamin B1 expression in human pancreatic cancer pathogenesis and betulinic acid–based therapy. Experimental Design: We used cDNA microarray to identify betulinic acid target genes and used tissue microarray to determine the expression levels of lamin B1 in pancreatic cancer tissues and to define their relationship with the clinicopathologic characteristics of pancreatic cancer. We also used in vitro and in vivo models to determine the biologic impacts of altered lamin B1 expression on and mechanisms underlying lamin B1 overexpression in human pancreatic cancer. Results: We found that lamin B1 was significantly downregulated by betulinic acid treatment in pancreatic cancer in both in vitro culture and xenograft models. Overexpression of lamin B1 was pronounced in human pancreatic cancer, and increased lamin B1 expression was directly associated with low-grade differentiation, increased incidence of distant metastasis, and poor prognosis of patients with pancreatic cancer. Furthermore, knockdown of lamin B1 significantly attenuated the proliferation, invasion, and tumorigenicity of pancreatic cancer cells. Conclusions: Lamin B1 plays an important role in pancreatic cancer pathogenesis and is a novel therapeutic target of betulinic acid treatment. Clin Cancer Res; 19(17); 4651–61. ©2013 AACR.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal diseases and is the fourth leading cause of cancer-related deaths.¹ x 1 Hidalgo, M. Pancreatic cancer. N Engl J Med. 2010; 362: 1605–1617 Crossref | PubMed | Scopus (1493) | Google Scholar See all References Although resection is the best choice for treatment of pancreatic cancer, most cases are diagnosed at late stages, making the patients poor candidates for resection. An explosion in knowledge of the molecular genesis of pancreatic cancer has resulted in definition of PDAC as a cancer with alterations in a wide range of signaling cascades; in contrast, tumorigenesis is driven by a single targetable oncogene in certain tumors.² x 2 Jones, S., Zhang, X., Parsons, D.W. et al. Core signaling pathways in human pancreatic cancers revealed by global genomic analyses. Science. 2008; 321: 1801–1806 Crossref | PubMed | Scopus (2319) | Google Scholar See all References Nonetheless, certain signaling pathways and key nodal points act as core genetic alterations and commonly are detected in PDAC cells. Identifying the mechanisms underlying dysregulation of these core alterations should help the development of innovative strategies for prevention, early detection, and treatment of PDAC.

The transcription factor Forkhead box M1 (FOXM1) plays important roles in oncogenesis. However, the expression statuses of FOXM1 isoforms and their impact on and molecular basis in oncogenesis are unknown. We sought to determine the identities of FOXM1 isoforms in and the impact of their expression on pancreatic cancer development and progression using human tissues, cell lines, and animal models. Overexpression of FOXM1 mRNA and protein was pronounced in human pancreatic tumors and cancer cell lines. We identified five FOXM1 isoforms present in pancreatic cancer: FOXM1a, FOXM1b, and FOXM1c along with two isoforms tentatively designated as FOXM1b1 and FOXM1b2 because they were closely related to FOXM1b. Interestingly, FOXM1c was predominantly expressed in pancreatic tumors and cancer cell lines, whereas FOXM1a expression was generally undetectable in them. Functional analysis revealed that FOXM1b, FOXM1b1, FOXM1b2, and FOXM1c, but not FOXM1a, promoted pancreatic tumor growth and metastasis. Consistently, FOXM1b, FOXM1b1, FOXM1b2, and FOXM1c activated transcription of their typical downstream genes. Also, Sp1 mechanistically activated the FOXM1 promoter, whereas Krüppel-like factor 4 (KLF4) repressed its activity. Finally, we identified an Sp1- and KLF4-binding site in the FOXM1 promoter and showed that both Sp1 and KLF4 protein bound directly to it. Deletion mutation of this binding site significantly attenuated the transcriptional regulation of the FOXM1 promoter positively by Sp1 and negatively by KLF4. We showed that overexpression of specific FOXM1 isoforms critically regulates pancreatic cancer development and progression by enhancing tumor cell invasion and metastasis. Our findings strongly suggest that targeting specific FOXM1 isoforms effectively attenuates pancreatic cancer development and progression. Cancer Res; 73(13); 3987–96. ©2013 AACR.

Metformin potentiates rapamycin and cisplatin in gastric cancer in mice Metformin potentiates rapamycin and cisplatin in gastric cancer in mice

The therapeutic and prognostic value of the glycolytic enzymes hexokinase, phosphofructokinase, and pyruvate kinase (PK) has been implicated in a variety of cancers, while their roles in treatment of and prognosis for hilar cholangiocarcinoma (HC) remain unclear. In this study, we determined the expression of PKM2 in and its impact on biology and clinical outcome of human HC. The regulation and function of PKM2 in HC pathogenesis was evaluated using human tissues, molecular and cell biology, and animal models, and its prognostic significance was determined according to its impact on patient survival. We found that expression of hexokinase 1 and the M2 splice isoform of PK (PKM2) was upregulated in HC tissues and that this expression correlated with tumor recurrence and outcome. PKM2 expression was increased in HC cases with chronic cholangitis as demonstrated by isobaric tags for relative and absolute quantification. High PKM2 expression was highly correlated with high syndecan 2 (SDC2) expression and neural invasion. PKM2 downregulation led to a decrease in SDC2 expression. Treatment with metformin markedly suppressed PKM2 and SDC2 expression at both the transcriptional and posttranscriptional levels and inhibited HC cell proliferation and tumor growth. PKM2 regulates neural invasion of HC cells at least in part via regulation of SDC2. Inhibition of PKM2 and SDC2 expression contributes to the therapeutic effect of metformin on HC. Therefore, PKM2 is an independent prognostic factor and potential therapeutic target for human HC.