sCLU regulates cisplatin chemosensitivity of lung cancer cells in vivo

Decoding CLU (Clusterin): Conquering cancer treatment resistance and immunological barriers

One major obstacle in the treatment of cancer is the presence of proteins resistant to cancer therapy, which can impede the effectiveness of traditional approaches such as radiation and chemotherapy. This resistance can lead to disease progression and cause treatment failure. Extensive research is currently focused on studying these proteins to create tailored treatments that can circumvent resistance mechanisms. CLU (Clusterin), a chaperone protein, has gained notoriety for its role in promoting resistance to a wide range of cancer treatments, including chemotherapy, radiation therapy, and targeted therapy. The protein has also been discovered to have a role in regulating the immunosuppressive environment within tumors. Its ability to influence oncogenic signaling and inhibit cell death bolster cancer cells resistant against treatments, which poses a significant challenge in the field of oncology. Researchers are actively investigating to the mechanisms by which CLU exerts its resistance-promoting effects, with the ultimate goal of developing strategies to circumvent its impact and enhance the effectiveness of cancer therapies. By exploring CLU's impact on cancer, resistance mechanisms, tumor microenvironment (TME), and therapeutic strategies, this review aims to contribute to the ongoing efforts to improve cancer treatment outcomes.

The role and function of CLU in cancer biology and therapy

Clusterin (CLU) is a highly evolutionary conserved glycoprotein with multiple isoform-specific functions and is widely distributed in different species. Accumulated evidence has shown the prominent role of CLU in regulating several essential physiological processes, including programmed cell death, metastasis, invasion, proliferation and cell growth via regulating diverse signaling pathways to mediate cancer progression in various cancers, such as prostate, breast, lung, liver, colon, bladder and pancreatic cancer. Several studies have revealed the potential benefit of inhibiting CLU in CLU inhibition-based targeted cancer therapies in vitro, in vivo or in human, suggesting CLU is a promising therapeutic target. This review discusses the multiple functions and mechanisms of CLU in regulating tumor progression of various cancers and summarizes the inhibitors of CLU used in CLU inhibition-based targeted cancer therapies.

Clusterin as modulator of carcinogenesis: A potential avenue for targeted cancer therapy

Clusterin (CLU) is an evolutionary conserved molecular chaperone present in different human tissues and fluids and established to be a significant cancer regulator. It controls several cancer-associated cellular events, including cancer cell proliferation, stemness, survival, metastasis, epithelial-mesenchymal transition, therapy resistance, and inhibition of programmed cell death to support cancer growth and recurrence. This multifunctional role of CLU makes it an ideal target for cancer control. More importantly, genetic and antisense-mediated (OGX-011) inhibition of CLU enhances the anticancer potential of different FDA-approved chemotherapeutic drugs at the clinical level, improving patient's survival. In this review, we have discussed the detailed mechanism of CLU-mediated modulation of different cancer-associated signaling pathways. We have also provided updated information on the current preclinical and clinical findings that drive trials in various cancer types for potential targeted cancer therapy.

Cisplatin-resistant triple-negative breast cancer subtypes: multiple mechanisms of resistance

BACKGROUND

Understanding mechanisms underlying specific chemotherapeutic responses in subtypes of cancer may improve identification of treatment strategies most likely to benefit particular patients. For example, triple-negative breast cancer (TNBC) patients have variable response to the chemotherapeutic agent cisplatin. Understanding the basis of treatment response in cancer subtypes will lead to more informed decisions about selection of treatment strategies.

METHODS

In this study we used an integrative functional genomics approach to investigate the molecular mechanisms underlying known cisplatin-response differences among subtypes of TNBC. To identify changes in gene expression that could explain mechanisms of resistance, we examined 102 evolutionarily conserved cisplatin-associated genes, evaluating their differential expression in the cisplatin-sensitive, basal-like 1 (BL1) and basal-like 2 (BL2) subtypes, and the two cisplatin-resistant, luminal androgen receptor (LAR) and mesenchymal (M) subtypes of TNBC.

RESULTS

We found 20 genes that were differentially expressed in at least one subtype. Fifteen of the 20 genes are associated with cell death and are distributed among all TNBC subtypes. The less cisplatin-responsive LAR and M TNBC subtypes show different regulation of 13 genes compared to the more sensitive BL1 and BL2 subtypes. These 13 genes identify a variety of cisplatin-resistance mechanisms including increased transport and detoxification of cisplatin, and mis-regulation of the epithelial to mesenchymal transition.

CONCLUSIONS

We identified gene signatures in resistant TNBC subtypes indicative of mechanisms of cisplatin. Our results indicate that response to cisplatin in TNBC has a complex foundation based on impact of treatment on distinct cellular pathways. We find that examination of expression data in the context of heterogeneous data such as drug-gene interactions leads to a better understanding of mechanisms at work in cancer therapy response.

Differential expression profile analysis of cisplatin‑regulated miRNAs in a human gastric cancer cell line

Cisplatin, one of the most commonly used drugs in combination chemotherapy, is an effective anti‑tumor agent widely used for diverse tumor types. MicroRNAs (miRNAs/miRs) are involved in the occurrence, development, diagnosis and treatment of cancer. Therefore, the aim of the current study was to explore whether cisplatin exerts anticancer effects by causing differential expression of miRNAs in human gastric cancer cells. The human gastric cancer cell line NCI‑N87 was cultured with a certain dose of cisplatin and high‑throughput sequencing combined with reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) was performed to detect cisplatin‑regulated miRNAs. miRNAs upregulated and downregulated following cisplatin exposure were analyzed. High‑throughput sequencing revealed 33 upregulated and 16 downregulated miRNAs. A total of five significantly upregulated and five significantly downregulated miRNAs were identified by RT‑qPCR. The expression levels of hsa‑miR‑1246 and hsa‑miR‑892b were consistent with the results obtained from high‑throughput sequencing. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway clustering of cisplatin‑regulated miRNAs revealed that the miRNAs regulated genes involved in several biological processes and signaling pathways. The results obtained in the current study suggested that cisplatin may exert an important anticancer effect in gastric cancer via complex biological processes and signaling pathways.

The role of Clusterin in cancer metastasis

Clusterin is a conserved glycoprotein that has been characterized from almost all human tissues and fluids and plays a key role in cellular stress response and survival. Recently, research efforts have been contributed to explore the function of Clusterin in cancer metastasis, which is particularly important to design the strategies for treating metastatic patients. Evidence collected has demonstrated that Clusterin is overexpressed in tumor metastatic patients and experimental metastasis models. Specifically, Clusterin has been shown to have the role in anti-apoptotic capacities, development of therapy resistance and induction of epithelial–mesenchymal transition, all associated with cancer metastasis. Inhibition of Clusterin is known to increase the cytotoxic effects of chemotherapeutic agents and improves advanced cancer patients survival in clinical trials. Our unpublished data have demonstrated that Clusterin is overexpressed in bladder cancer and metformin, a well-known metabolism modulator specifically targets Clusterin by inhibiting migration of bladder cancer cells. In this review, we provide a general view of how Clusterin modulates cancer metastasis and update current understanding of detailed molecular mechanisms underlying of Clusterin for developing cancer management in future.

Downregulation of secreted clusterin potentiates the lethality of sorafenib in hepatocellular carcinoma in association with the inhibition of ERK1/2 signals

Secretory clusterin (sCLU) is overexpressed in cancer and is associated with resistance to chemotherapy in several types of cancer, including hepatocellular carcinoma (HCC). Sorafenib (SOR), a multikinase inhibitor of Raf/mitogen‑activated protein kinase kinase/extracellular signal‑regulated kinase (ERK) signaling and the receptor tyrosine kinase, is recognized as the standard therapeutic strategy for patients with advanced HCC. However, the role of sCLU in the resistance of HCC to SOR remains to be fully elucidated. In the present study, sCLU was silenced by CLU short hairpin (sh)RNA in Bel‑7402 and SMMC‑7721 cell lines, following which the cells were treated with SOR. Cell proliferation was determined using a CCK‑8 assay. Apoptosis was quantified using flow cytometry. The production of sCLU, B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated X sprotein and phosphorylated (p)ERK1/2 was analyzed using western blot analysis. The results showed that sCLU was overexpressed in three HCC cell lines. The downregulation of sCLU by CLU shRNA synergistically increased SOR sensitivity in the Bel‑7402 and SMMC‑7721 cells, and potentiated SOR‑induced cell apoptosis. In addition, silencing sCLU or combination with PD98059 decreased the SOR‑induced activation of pERK1/2. These findings indicate a novel treatment strategy for HCC.

HSPA12B overexpression induces cisplatin resistance in non-small-cell lung cancer by regulating the PI3K/Akt/NF-κB signaling pathway

Although cisplatin (CDDP) is widely used for non-small-cell lung cancer (NSCLC) treatment, resistance remains a major problem that restricts its efficacy. Therefore, identification of drugs that reverse or prevent resistance to CDDP in NSCLC has been a focus of a number of studies. The results of the present study revealed the effect of heat shock protein family A member 12B (HSPA12B) overexpression on chemoresistance in A549 cells in vitro. The effect of HSPA12B overexpression on chemoresistance in mice bearing A549 xenografted tumors was then determined via stable HSPA12B transfection. Finally, the effects of HSPA12B overexpression on the phosphorylation of protein kinase B (Akt) and nuclear factor-κB inhibitor α (IκBα), and the expression of the anti-apoptotic protein B-cell lymphoma 2 (Bcl-2) and the pro-apoptotic protein cleaved caspase-3 were determined by western blot analysis. The results demonstrated that HSPA12B overexpression increased resistance to CDDP in NSCLC cells in vivo and in vitro by promoting cell growth and inhibiting CDDP-induced apoptosis. Mechanistically, this effect was mediated by the upregulation of phosphorylated (p-)Akt, p-IκBα and Bcl-2 and the downregulation of cleaved caspase-3. Therefore, the present study provides useful information pertaining to the identification and targeting of a CDDP-resistant population, and the development of potential therapeutics to improve the current treatment modalities in NSCLC.

O-linked N-acetylglucosamine transferase enhances secretory clusterin expression via liver X receptors and sterol response element binding protein regulation in cervical cancer

O-linked N-acetylglucosamine transferase (OGT) expression is increased in various cancer types, indicating the potential importance of O-GlcNAcylation in tumorigenesis. Secretory clusterin (sCLU) is involved in cancer cell proliferation and drug resistance, and recently, liver X receptors (LXRs) and sterol response element binding protein-1 (SREBP-1) were reported to regulate sCLU transcription. Here, we found that sCLU is significantly increased in cervical cancer cell lines, which have higher expression levels of O-GlcNAc and OGT than keratinocytes. OGT knockdown decreased expression of LXRs, SREBP-1 and sCLU through hypo-O-GlcNAcylation of LXRs. Additionally, treatment with Thiamet G, O-GlcNAcase OGA inhibitor, increased expression of O-GlcNAcylation and sCLU, and high glucose increased levels of LXRs, SREBP-1 and sCLU in HeLa cells. Moreover, OGT knockdown induced G₀/G₁ phase cell cycle arrest and late apoptosis in cisplatin-treated HeLa cells, and decreased viability compared to OGT intact HeLa cells. Taken together, these findings suggest that OGT, O-GlcNAcylated LXRs, and SREBP-1 increase sCLU expression in cervical cancer cells, which contributes to drug resistance.

Clusterin inhibition mediates sensitivity to chemotherapy and radiotherapy in human cancer

Since its discovery in 1983, the protein clusterin (CLU) has been isolated from almost all human tissues and fluids and linked to the development of different physiopathological processes, including carcinogenesis and tumor progression. During the last few years, several studies have shown the cytoprotective role of secretory CLU in tumor cells, inhibiting their apoptosis and enhancing their resistance to conventional treatments including hormone depletion, chemotherapy, and radiotherapy. In an effort to determine the therapeutic potential that the inhibition of this protein could have on the development of new strategies for cancer treatment, numerous studies have been carried out in this field, with results, in most cases, satisfactory but sometimes contradictory. In this document, we summarize for the first time the current knowledge of the effects that CLU inhibition has on sensitizing tumor cells to conventional cancer treatments and discuss its importance in the development of new strategies against cancer.

Label-free quantitative proteomic analysis of benzo(a)pyrene-transformed 16HBE cells serum-free culture supernatant and xenografted nude mice sera

To screen potential biomarkers of benzo(a)pyrene (BaP)-induced lung cancer, the proteomic profiles of BaP-transformed 16HBE cell line T-16HBE-C1 cells serum-free culture supernatant and xenografted nude mice sera were compared with those of 16HBE group by utilizing label-free quantitative proteomic strategy. By employing nano-LC-MS/MS technology followed by MaxQuant and Perseus processing, 489 differentially expressed proteins were identified between T-16HBE-C1 and 16HBE cells serum-free culture supernatant, and 49 significantly up-regulated proteins were identified in T-16HBE-C1 xenografted nude mice sera. Three proteins neuropilin-2 (NRP2), clusterin (CLU) and A-kinase anchor protein 12 (AKAP12) were up-regulated in the serum-free culture supernatant of T-16HBE-C1 cells. These 3 human proteins were present in the sera of nude mice xenografted with T-16HBE-C1 cells, but were undetectable in mice xenografted with 16HBE cells. The proteomic results of NRP2 and AKAP12 were confirmed by Western blotting and enzyme-linked immunosorbent assays, respectively. Moreover, the serum NRP2 levels were significantly elevated at the 4th day after tumor cell implantation and showed good positive correlation with tumor growth characterized by tumor volume. In conclusion, serum NRP2, CLU and AKAP12 could be potential biomarkers of BaP-induced lung cancer. The proteomic results will gain deeper insights into the mechanisms of BaP-induced carcinogenesis.