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Ubiquilin‑1 (UBQLN1) is an essential factor for the maintenance of proteostasis in cells. It is important for the regulation of different protein degradation mechanisms, including the ubiquitin‑proteasome system, autophagy and endoplasmic reticulum‑associated protein degradation pathways. However, the role of UBQLN1 in cancer progression remains largely unknown. In the present study, the expression, functions and molecular mechanisms of UBQLN1 in breast cancer tissue samples and cell lines were explored. Immunohistochemical and bioinformatics analyses revealed that UBQLN1 expression was significantly upregulated in breast cancer tissues and cell lines. UBQLN1 expression in breast cancer was significantly associated with lymph node metastasis and TNM stage. Moreover, a high UBQLN1 expression was a predictor of an unfavorable survival in patients with breast cancer. In vitro , UBQLN1 silencing markedly inhibited cell migration and invasion, epithelial‑to‑mesenchymal transition (EMT) and MMP expression. UBQLN1 silencing attenuated the stem cell‑like properties of breast cancer cells, including their mammosphere‑forming abilities. UBQLN1 knockdown also enhanced breast cancer cell chemosensitivity to paclitaxel. The expression levels of the stem cell markers. Aldehyde dehydrogenase 1 (ALDH1), Oct‑4 and Sox2 were significantly decreased in the cells in which UBQLN1 was silenced, whereas breast cancer stem cells exhibited an increased expression of UBQLN1. Mechanistically, UBQLN1 knockdown inhibited the activation of AKT signaling, as revealed by the increased PTEN expression and the decreased expression of phosphorylated AKT in cells in which UBQLN1 was silenced. On the whole, the present study demonstrates that UBQLN1 is aberrantly upregulated in breast cancer and predicts a poor prognosis. The silencing of UBQLN1 inhibited the invasion, EMT and stemness of breast cancer cells, possibly via AKT signaling.

Parthenolide has been demonstrated to have anticancer effects against various types of cancer. However, the functional role of parthenolid has yet to be clearly reported in renal cell carcinoma (RCC). The aim of the present study was to investigate the effect of parthenolide in RCC 786‑O and ACHN cells. CCK‑8 and colony‑formation assays were used to observe the proliferation of RCC 786‑O and ACHN cells. Migration and invasion abilities were assessed through Transwell assays. The stem cell‑like properties of RCC cell lines were evaluated by mammosphere formation assay. Western blot analysis was used to investigate the metastasis and epithelial‑mesenchymal transition (EMT) induced by parthenolide on the expression levels of MMP2, MMP9, E‑cadherin, N‑cadherin, vimentin and snail. The results revealed that when the cells were treated with various concentrations of parthenolide, the rate of proliferation and growth was decreased in 786‑O and ACHN cells. The number of invasive cells in a field was approximately 170, 90, 40 and 190, 150, 70 in 786‑O and ACHN cells with 0, 4 and 8 µM of parthenolide treatment. MMP‑2/‑9 expression (P<0.05) was inhibited by parthenolide. The protein levels of E‑cadherin were increased (P<0.05) and N‑cadherin, vimentin and snail were decreased (P<0.05) by parthenolide treatment. In addition, Parthenolide inhibited the expression of cancer stem cell markers and the PI3K/AKT pathway. The present study confirmed that parthenolide inhibited RCC cell proliferation and metastasis and suppressed the stem cell‑like properties of RCC cell lines, which could be a potential strategy to treat RCC. However, further molecular mechanisms of parthenolide in RCC should be observed and reported in the future.

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant cancer of the digestive tract that has a high potential for metastasis and a poor prognosis. Girdin was first reported in 2005 as an actin‑binding protein and was designated as Akt‑phosphorylation enhancer (APE); thus, Girdin has been revealed to have an important role in regulating cancer development. There is additional evidence indicating that Girdin is associated with cell proliferation, migration, invasion and survival in certain cancers. However, the potential mechanisms involving Girdin and mobility in pancreatic cancer have not been elucidated. In the present study, it was revealed that Girdin was highly expressed in pancreatic cancer tissue and was associated with tumor grade. The present study, to the best of our knowledge, is the first aimed at investigating the unknown role of Girdin in PDAC metastasis. A short hairpin RNA for Girdin (sh‑Girdin) was successfully constructed with recombinant adenoviral vectors to suppress the expression of Girdin in pancreatic cancer cell lines (PANC‑1 and BXPC‑3). The silencing efficiency of the Girdin shRNA was determined by RT‑qPCR and western blot analysis, and decreased Girdin expression in the cytoplasm was revealed by immunofluorescence detection. Then, sulforhodamine B (SRB) and colony formation assays were used to confirm that the knockdown of Girdin inhibited proliferation in vitro, and Transwell assays were used to examine the influence of Girdin knockdown on cellular mobility. Animal experiments also confirmed that silencing the expression of Girdin in pancreatic cancer cells inhibited the growth and metastasis of pancreatic cancer in vivo. Transforming growth factor‑β (TGF‑β) is a common inducer of epithelial‑mesenchymal transition (EMT) and can effectively induce EMT in PDAC. Notably, TGF‑β‑treated cells exhibited changes in the classic biological markers of EMT. The expression of E‑cadherin, a marker of the epithelial phenotype, increased, and the expression of N‑cadherin and vimentin, markers of the interstitial phenotype, decreased in response to sh‑Girdin. According to these experiments, Girdin may affect pancreatic cancer progression and development by interacting with vimentin. Therefore, there is evidence indicating that Girdin could be designated as a prognostic biological indicator and a candidate therapeutic target for pancreatic cancer.

Girdin functions as an Akt phosphorylation enhancer (APE), which expedites the proliferation and survival of many types of tumours. However, the influence of Girdin on pancreatic cancer and the underlying molecular mechanisms have yet to be uncovered. Hence, in the present study, we sought to elucidate the function of Girdin in pancreatic cancer malignancy, particularly its role in pancreatic cancer cell proliferation, migration and apoptosis. Immunohistochemistry (IHC) was used to evaluate Girdin expression in pancreatic cancer tissues and to analyse its correlation with pathological grade. Girdin expression was further validated in pancreatic cancer cell lines (AsPC‑1, BxPC‑3 and PANC‑1), and human pancreatic ductal epithelial (HPNE) cells were used as a control. Recombinant adenovirus vectors containing Girdin‑siRNA were constructed to inhibit Girdin expression and were used in subsequent experiments to determine the effects of Girdin silencing on pancreatic cancer cells. Girdin silencing suppressed pancreatic cancer cell proliferation and induced pancreatic cancer cell apoptosis in vitro and in vivo. According to the results of further mechanistic investigations, Girdin may regulate cell processes through the phosphatidylinositol‑3‑kinase/protein kinase B (PI3K/Akt) signalling pathway to exert additive effects on pancreatic cancer.

Autophagy is a key catabolic process, in which cytosolic cargo is engulfed by the formation of a double membrane and then degraded through the fusing of autophagosomes with lysosomes. Autophagy is a constitutively active, evolutionarily conserved, catabolic process important for the maintenance of homeostasis in cellular stress responses and cell survival. Although the mechanisms of autophagy have not yet been fully elucidated, emerging evidence suggests that it plays a dual role in breast cancer and in maintaining the activity of breast cancer stem cells (CSCs). However, it may play a complex role in breast CSC therapy. Breast CSCs, a population of cells with the ability to self-renew, differentiate, and initiate and sustain tumor growth, play an essential role in cancer recurrence, anticancer resistance and metastasis. In addition, the elucidation of the association between autophagy and apoptosis in the tumor context is crucial in order to better address appropriate therapy strategies. In the present review, a summary of the mechanisms and roles of autophagy in breast cancer and CSCs is presented. The potential value of such autophagy modulators in the development of novel breast cancer therapies is discussed.